Barry D. Kahan, M.D., Ph.D.

• Professor Emeritus
• The University of Texas Medical School at Houston
• Houston, Texas

These will treatment for sciatica buy 10mg endep otc, sooner or later xanax medications for anxiety purchase cheap endep on-line, be sufficiently well specified to be used as indications of the likelihood of the presence of awareness in brain-damaged patients and as the grounds for making predictions about the likelihood of recovery of compromised consciousness medications in mexico buy genuine endep line. However medicine to stop runny nose buy genuine endep online, no evidence that conceptspecific and no evidence that transient experiencespecific patterns are about to be identified are to be found in the literature medicine garden purchase endep in india. Functional brain imaging during anesthesia in humans: Effects of halothane on global and regional cerebral glucose metabolism medicine engineering buy generic endep on line. Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient. Breakdown of within- and between-network resting state functional magnetic resonance imaging connectivity during propofol-induced loss of consciousness. On the biological plausibility of grandmother cells: Implications for neural network theories in psychology and neuroscience. Distributed and overlapping representations of faces and objects in ventral temporal cortex. Voxelbased statistical analysis of cerebral glucose metabolism in patients with permanent vegetative state after acquired brain injury. Unresponsive wakefulness syndrome: A new name for the vegetative state or apallic syndrome. Visual image reconstruction from human brain activity using a combination of multiscale local image decoders. Partially distributed representations of objects and faces in ventral temporal cortex. Residual cerebral activity and behavioural fragments can remain in the persistently vegetative brain. Diagnostic and prognostic use of bispectral index in coma, vegetative state and related disorders. Single-trial magnetoencephalography signals encoded as an unfolding decision process. Visual response properties of cells in the ventral and dorsal parts of the macaque inferotemporal cortex. Default network connectivity reflects the level of consciousness in non-communicative brain-damaged patients. Papanicolaou Abstract this chapter focuses on the search for mnemonic traces of concepts that are thought to exist in the form of neuronal circuits in the brain. It begins with a review of the evidence derived from observations of the effects of focal brain lesions suggesting that there are several brain regions specialized for recognizing objects belonging to different categories. It then considers brain areas that have been identified through functional neuroimaging, including the fusiform face area, the parahippocampal place area, and the extra-striate body area. It also examines the specialization of the anterior part of the temporal lobes, especially the left, for naming, and whether these and other brain areas contain mnemonic traces of concepts or traces of cardinal concept features. Finally, it discusses the "top-down" activation of category-specific areas and the idea of distributed storage of concept features. It appears that there are no doubts that such traces representing either concepts or features shared by many concepts exist in the form of neuronal circuits in the brain despite early failure to find them. On the contrary, it is believed that, with modern investigative techniques, not only "questions concerning the possibility that different object properties are stored in different brain regions can be addressed" (Martin, 2007, p. That belief, however, after having fulfilled its role of engendering further explorations, has tactfully retreated into the mists of brain science lore. This may have occurred because of the rarity and unpredictability of the replications of the results that engendered it (but see Bartolomei et al. Whatever the reason, the fact is that now most literature on memory storage issues concerns some types of concepts and not personal memories. On one view, a view forcefully advanced by Berkeley (see especially his Introduction in Berkeley, 1710/ 1881), the content of abstract concepts is but a collection of concrete. Whether this view is correct is of little importance here since, with a few exceptions (see. More specifically, it concerns the identification and localization of those neuronal circuits that code for either the names or the contents of such concepts. There are several conjectures about the form and arrangement of those concept-specific neuronal circuits in the brain, most likely along the cortical surface. They are all derived from the Hebbian notion of cell assemblies (Hebb, 1949) whereby separate circuits of interconnected neurons code for the names of concepts. It has also been proposed that single cells may represent whole concepts-an idea that has arisen from single-cell recording studies (see. Accordingly, the recognition of instances of a concept-that is, recognition of a specific stimulus object of those that are encountered in daily life and constitute parts of the stream of consciousness and, later, parts of episodic 232 Papanicol aou memories-is said to be accomplished in the following manner: the stimulus object results in sensory activity in the primary sensory and association cortices that code its physical features, which constitute its form. That activity, in turn, ignites the dormant name circuit and other semantic circuits of the concept, and the reverberation of all these circuits constitutes the neuronal correlate of the experience of recognition of the object. Hearing or reading the name of the concept also suffices to activate the rest of the concept circuits as well (see. This very basic model may be embellished by positing (1) processing operations, each with its own neuronal mechanism or network, such as the operation of retrieval. Such embellishments, however, give rise to the question of whether the same neurons that store the concept features are also part of the aforementioned mechanisms, and, if so, also to the problem of how to image them separately if we are to assert that a particular functional image is capturing the stored concept rather than the mechanism of its construction. Evidence Provided by Lesion Data If concepts are indeed stored in terms of cell assemblies, to assess through neuroimaging the nature and location of the cell assemblies one must activate them, either through presentation of their names, through verbal descriptions of their features and their functions, or through presentation of their pictures. In doing so, one is inadvertently also addressing the question of object encoding. On the basis of observations of the effects of focal brain lesions, which indicate that concept circuits are segregated by category on the cortical surface, and on the basis of functional neuroimaging findings to the same effect, three basic types of proposals have been advanced. For some, this appears to be the case for at least such concepts as those of animals and conspecifics that evolutionary pressures have made it imperative that we recognize and respond to immediately (see. The second proposal began as a hypothesis put forth by Elizabeth Warrington and her co-workers (McCarthy & Warrington, 1990, 1994; Warrington & McCarthy, 1983, 1987; Warrington & Shallice, 1984) stating that the spatially segregated semantic circuits do not represent entire concepts but represent instead the defining attributes of objects belonging to a particular category. In the case of the "living things" category, they represent sensory attributes on the basis of which animals may be recognized most readily. In the case of the "artifacts" category, the semantic circuits represent some "functional" attributes that most readily distinguish among and identify manmade things. This idea-that semantic circuits represent object attributes rather than entire object concepts-gave impetus to the development of several additional and more detailed models describing how the activation of circuits representing particular semantic features results in the activation of the rest of the concept circuits and, consequently, in the recognition of the object in question (see. Differences aside, the first two models that arose from the lesion literature share the claim that concept-specific mnemonic traces are arranged on the cortical mantle according to some category or other. Therefore, the first task investigators faced was to identify which categories are represented in which brain areas since there is an inexhaustible number of ways that concepts and semantic features can be grouped. Some ideas regarding the types of categories represented by cortical circuits and the spatial order of their arrangement have emerged from early observations of the effects of focal lesions on different classes of memories. These range from selective deficits for faces and colors to deficits in knowledge of people versus objects (Tranel, Damasio, & Damasio, 1997); selective deficits in recognizing famous people without any other category deficits (Evans, Heggs, Antoun, & Hodges, 1995); gradients of difficulty, independent of lesion site, with abstract concepts being affected more than concrete ones (an observation going back to the 19th century; see. In a well-known review of that early literature, Gainotti (2000) summarized what appeared to be reproducible findings as follows: first, knowledge of living things is compromised by lesions affecting the anterior medial and inferior aspects of both the left and right temporal lobes. Second, knowledge of tools is compromised by lesions affecting the dorsolateral aspect of the left frontal, temporal, and parietal cortices. Mnemonic Traces of Concepts 233 In a subsequent report involving a large patient sample (Damasio, Tranel, Grabowski, Adolphs, & Damasio, 2004), a somewhat different picture emerged: on the basis of the effects of focal lesions, it appeared that left hemisphere lesions produce deficits in naming, whereas bilateral lesions produce deficits in object recognition. That is, it appeared as if focal lesions interfere with name circuits, whereas bilateral lesions interfere with circuits representing general knowledge about the objects. Moreover, it appeared as if mnemonic traces of both kinds are further segregated in that the naming of famous people was affected by lesions in the left temporal pole; that of animals was affected by lesions in the anterior part of the left inferior temporal gyrus, the anterior insula, and the dorsal temporo-occipital junction; and the naming of tools by lesions in the posterior lateral temporaloccipital-parietal junction, the inferior sector of the pre- and post-central gyri and the insula, whereas the naming of musical instruments was compromised by lesions in the temporal pole, the anterior part of the left inferior temporal gyrus, the posterior part of the lateral temporal cortex, the insula, and the inferior part of the pre- and post-central gyri. On the other hand, semantic circuits appeared to be compromised by bilateral lesions, but mostly by lesions in the right hemisphere. These lesions also selectively affected knowledge of objects belonging to the aforementioned categories depending on their precise location, thus pointing, again, to a spatial segregation of semantic circuits by category. However, using correlations of gray mater volume and the naming accuracy of line drawings of living and non-living objects, in a series of 152 patients, Brambati et al. Namely, those for living things (animals and fruits) appeared to be located in the anterior and medial part of the right temporal lobe and those for non-living things in the posterior part of the left middle temporal gyrus. Evidently, variability in the precise cortical loci of the putative name and semantic circuits of objects belonging to different categories is considerable from one study to the next, as is the variability of the selective deficits produced by particular lesions from which the categories of semantic and name circuits are deduced. Yet there is no reason to doubt the accuracy of these observations as far as they go. The difficulty with interpreting them is due to a number of factors, the detailed examination of which is beyond the scope of this chapter. Very briefly, it is difficult enough to match consistently 234 Papanicol aou lesion locations with particular categories of concepts when the lesions are of varying extent, shape, and etiology, but it is much harder to certify that the deficits observed are indeed due to the selective interference of the lesion with the category the observer-clinicians postulate, which is expressed in their choice of test items that are appropriate for assessing knowledge of the chosen nominal categories. To be specific: a patient may be incapable of recognizing an object belonging to a given category, yet the reason for that selective deficit may be due to a host of other factors that are simultaneously operative, such as patient-specific familiarity with the particular set of test items-to say nothing of the possibility that any object may very well belong to a number of alternative and not mutually exclusive categories as, for example, the category of things that involve action, the category of big things, of usually moving or usually stationary things, of things of great evolutionary significance, of bright things or odorless things, and so on since there is no reason to believe that the brain follows the Aristotelian classification scheme by genus and difference or, for that matter, any other classification scheme we may postulate a priori. But, variability in the specification of the type of categories of concepts or cardinal concept features associated with particular lesion locations aside, the central question here is the soundness of interpreting the selectivity of any such deficit as interference with mnemonic traces. Inability or difficulty in naming objects and inability or difficulty in identifying the nature of objects seen or described may be due to a number of factors in addition to interference with the concept-specific circuits themselves. The number of these factors depends on the particular model of recognition one is implicitly or explicitly adopting. In the case of the general "embellished" model sketched earlier, the deficits can be attributed to (1) the degradation of the network of the cognitive operation of retrieval of the semantic circuits representing whole concepts, (2) interference with the retrieval operation of feature-specific circuits, and/ or (3) interference with the operation of binding the sensory features into a pictorial representation or mental image of the object, in addition to or instead of (4) the degradation of the concept-specific circuits themselves. As mentioned previously, of these basic alternatives, the first three could conceivably be eliminated on the assumption that the mechanisms of retrieval, binding, and integration are intact since the patients have difficulty in retrieving, binding, and reconstructing only some specific concepts. Yet it is always possible that deficits associated with different lesion locations are only apparently category specific but in fact may affect all categories, albeit to different degrees. It is also possible that retrieval, binding, or integration mechanisms are specialized and attached to each of the several different categories of objects. Moreover, it is possible that the process of recognition is quite different from the one depicted in the most prominent models and requires neither special nor general mechanisms for activating mnemonic traces in order to compare them to sensory inputs. For example, lesions in the anterior part of the temporal lobes are said to degrade the semantic circuits of living things (Gainotti, 2000) or only the name circuits of objects (Damasio et al. Accordingly, to decide among the alternatives, one should seek the best-fitting interpretation of regional brain specialization that the empirical data of lesion and functional neuroimaging studies allow-provided, of course, that the assumption that mnemonic traces do exist is true. One such that comes to mind is if particular objects or narrowly defined categories were irrevocably lost in associative agnosia or if specific concept names were similarly lost in cases of anomia. Instead, what appears to be a permanently eradicated memory is only inaccessible at the time of testing, Accordingly, not having proof that specific memories are ever eradicated one has to conclude that nothing certain about the traces has been discovered, and yet traces are still assumed to be there! At this juncture, the potential of functional neuroimaging for resolving some of the ambiguity becomes apparent. By using normal individuals with uncompromised brains, being able to visualize focal activation with a considerably greater degree of spatial resolution than that afforded by lesions and also having the possibility of experimenting with large numbers of alternative stimulus objects or object features, it appears possible that an answer as to which of them a particular cortical patch responds selectively can be approximated. Category-Selective Brain Areas Although the early lesion literature would suggest that there are several brain regions specialized for recognizing objects belonging to different categories, few such areas have been identified through functional neuroimaging. The evidence for the specialization of these areas will be briefly reviewed in order to address the question of whether-whatever else specialization may mean-it may also be interpreted as evidence that these areas contain mnemonic traces of concepts or traces of cardinal concept features. The Face Area Early hints for the existence of a brain area specialized for the recognition of faces came from observations of the selective effects of lesions in the ventral aspect of the occipito-temporal region of both hemispheres (or of only the right hemisphere) that encompass the fusiform gyrus (Benton, 1980; Damasio, Damasio, & Van Hoesen, 1982; Damasio, Tranel, & Damasio, 1990a; Lhermitte, Chain, Escourolle, Ducarne, & Pillon, 1972; Meadows, 1974a; Newcombe, 1979; Wilbrand, 1892). These lesions result in prosopagnosia, which is a specific case of object agnosia. The disorder has two characteristics that are relevant for the present discussion: first, notwithstanding the case of "the man who mistook his wife for a hat" (Sacks, 1985), patients with prosopagnosia do recognize a face as a face, unlike the person with apperceptive agnosia who cannot recognize a book as a book or a chair as a chair and could well mistake his wife for a hat (if he could only recognize hats). What such patients cannot recognize are particular faces, including their own face in the mirror (Damasio et al. Therefore, "prosopagnosia" may be a misnomer, and the condition should perhaps be called "token agnosia" or something equivalent instead; that is, agnosia for individual instances, tokens, or exemplars of a type or of a category, as contrasted to agnosia at large, which is the inability or the difficulty in identifying even the type of which particular objects are exemplars. But, in any case, on the basis of lesions, it is extremely difficult or impossible to identify the precise regions that specialize for the recognition of individual faces or other regions that may specialize for the recognition of individual instances of other object categories. As mentioned earlier, in the context of empirical studies, however extensive they might be, one may never assert with certitude that an area responds selectively to a particular object or particular feature. One may only reduce incrementally through successive studies the probability of misattribution of the specialization of an area for a particular object or feature. To address that issue, a condition was included in which pictures of individual houses and of individual faces were passively viewed. It could very well be the case that, whereas we habitually view faces in order to establish their identity and their distinctions from all other faces, we habitually view all other stimuli, including houses, only aiming to establish their category membership. Another stems from the fact that we have acquired greater facility and expertise in perceiving and identifying faces automatically, as compared to any other type of object. Certainly not whole concept circuits representing the type "face" because lesions that include this area do not eliminate the ability to perceive faces as faces and to discriminate them from other perceptual objects. Could it then include mnemonic traces of familiar faces or cardinal distinctive features of such faces, those that actually cannot be identified when it is lesioned We are led to the same conclusion through the examination of neuroimaging evidence regarding the function of other "specialized" brain regions, and this is presented next. Rather, they result in a reduction of the efficiency of discriminating pictures of bodies or body parts, a phenomenon reported only once in the clinical literature (Moro et al. Usually, they affect a broader area and result in object agnosia or prosopagnosia (see Moro et al. But bodies and body parts are rarely if ever static figures in the natural environment. Yet they simply reduce the efficiency of fine discrimination, which is indicative of interference with the mechanisms processing the visual input. The existence of such an area specialized for scenes was first reported by Epstein and Kanwisher (1998).

For instance medicine zocor discount endep online, it can guide the starting point for guide wire placement in the proximal pole with dorsal insertion treatment 02 academy cheap endep american express. It is also a valuable aid to assess the quality of the reduction treatment for depression discount endep 75mg online, to guard against screw cut-out treatment 5th metatarsal shaft fracture discount endep 25 mg otc, and to evaluate the rigidity of fixation as seemingly good screw purchase may not adequately stabilize a comminuted segment medications drugs prescription drugs cheap endep 25 mg mastercard. Indications for Arthroscopic-Assisted Percutaneous Scaphoid Fixation the goals of arthroscopic-assisted stabilization of scaphoid fractures are to reduce displaced fractures without an open incision and provide secure fixation that will permit early motion until solid union has been achieved medications journal discount endep 50mg. An unstable scaphoid fracture is defined as a lateral intrascaphoid angle of greater than 30 degrees, visible comminution, translation of 1 mm or more, or any visible gapping on any radiographic view. The wrist is placed in traction and flexed 45 degrees with a minifluoroscopy unit centered over the radiocarpal joint. This facilitates switching between arthroscopy and fluoroscopy without taking the wrist out of traction. When the wrist is flexed 45 degrees the scaphoid is angulated 90 degrees from the horizontal. This allows a dorsally applied x-ray beam to be parallel to the central scaphoid axis. Using a power drill, the guide wire is driven from an ulnar-dorsal to a radial-volar direction while keeping the wrist flexed. The guide wire is then advanced distally through the trapezium and out through the skin. The wrist can be extended if necessary once the trailing end clears the radiocarpal joint. If the fracture is displaced, the guide wire is withdrawn distally until it lies solely within the distal fragment. Once it is satisfactory, the reduction is captured by driving the guide wire proximally. The targeting K-wires are removed and the reamer is then introduced over the guide wire. Note that the guide wire has been advanced through the trapezium and out of the volar radial aspect of the thumb before reaming (arrows). The guide wire is driven volarly once more so that it is left protruding both proximally and distally. The wrist must remain flexed during this part otherwise the guide wire will bend and block both reaming and screw insertion. Care is taken not to ream through the subchondral bone because this reduces compression along the fracture site. Radiocarpal and midcarpal arthroscopy is now performed to check for screw cut-out. The rigidity of fracture fixation is assessed by palpating the fragments with a 1-mm hook probe or Freer elevator. After screw insertion, the guide wire is again driven distally if necessary to allow wrist extension and the fracture site is inspected arthroscopically. Volar Approach Screw fixation of the scaphoid through a volar approach is hindered by the trapezium, which prevents a straight-line approach to the central axis of the scaphoid. There is the added risk of screw cut-out through the concave volar surface of the scaphoid or through the dorsoulnar aspect of the proximal pole. The hand is suspended by the thumb alone in a single Chinese finger trap with no countertraction. This position extends the scaphoid and ulnarly deviates the wrist to improve access to the distal pole of the scaphoid. Most importantly, this position permits free rotation of the hand throughout the operation and the scaphoid remains in the center of the x-ray field throughout the procedure. The difference in length between the trailing end of each wire is the scaphoid length. This permits 2 mm of clearance of the screw at each end of the scaphoid, thus ensuring complete implantation without screw exposure. If it is necessary to take the wrist out of traction for this part, the screw length can be gauged by driving the guide wire volarly and distally until the trailing end is in the subchondral bone of the distal scaphoid pole and the process is repeated. This can be doublechecked by holding the screw over the snuffbox in the desired angle of insertion while performing a lateral fluoroscopic view. Note how the fracture line is reduced (arrows) and there are at least four screw threads in the proximal pole. The image intensifier C-arm is turned to a horizontal position and positioned so that the wrist is in the central axis. With the image intensifier in this position it is then possible to screen the scaphoid continuously around the axis of the radial column. K-wires can be inserted and used as joysticks to manipulate the fragments into position as necessary. The quality of the reduction can then be checked radiographically and, if necessary, arthroscopically, without disturbing the overall setup. The length of the screw is determined using a second guide wire of the same length inserted in the distal cortex of the scaphoid and undersized by 4 mm. The guide wire is then advanced through the proximal pole to exit on the dorsal aspect of the wrist to minimize the risk of inadvertent withdrawal, followed by reaming and screw insertion. Although some authors allow immediate and unrestricted motion, I prefer to immobilize the wrist in a short-arm thumb spica cast for 6 to 8 weeks. The authors were usually able to obtain a satisfactory dorsal-central position without drilling through the trapezium. The wrist is then placed into extension and ulnar deviation and the guide wire is advanced into the radius to prevent dislodgement after the length of the screw is determined. The scaphoid is reamed to within 2 to 3 mm of the proximal pole and a screw is inserted under fluoroscopic control. Arthroscopic Bone Grafting Ho recently described a technique of arthroscopic-assisted bone grafting of scaphoid nonunions. Loose implants (if present) are exchanged with a larger screw or multiple K-wires. Care is taken to preserve any intact cartilage or pseudocapsule over the nonunion site to avoid subsequent graft protrusion into the radiocarpal joint. Cancellous bone graft is tightly impacted into the nonunion site through an arthroscopic cannula. His series included 37 patients with established symptomatic nonunions and 6 patients with delayed unions with an average age of 28. Complications Screw length is often difficult to accurately determine by measuring a second K-wire that is placed parallel to the guide wire, due to interposition of soft tissue and obstruction by the edge of the trapezium. Penetration of the dorsal-radial surface of the scaphoid, which is exacerbated by any angular or humpback deformity aspect of the proximal pole, is common and can be minimized by using the pronated oblique views and undersizing the screw. Screw cut out of the tuberosity can sometimes be salvaged by using an open technique and creating a gliding trough in the trapezium, switching to a smaller diameter screw and levering the tuberosity volarly with an elevator. They incorrectly placed the screw above the subchondral bone despite live fluoroscopy in two specimens. They noted that these soft-tissue injuries could be avoided using a miniopen dorsal approach. Although there is a paucity of literature on this unusual fracture pattern, a few common elements have emerged. The coronal fractures can be complete and involve the entire body of the scaphoid. The scapholunate interosseous ligament can be completely detached or split into a dorsal and a volar half. The scapholunate ligament may be attached to either the volar or dorsal fragment because a coronal fracture can split the ligament into dorsal and volar halves. In some instances, reduction of the fracture fragments restores the integrity of the ligament, whereas in other cases a scapholunate ligament repair may be necessary. If the fracture plane is not along the exact coronal plane and is displaced, the superior and the inferior margins of the fracture can be seen as separate radiolucent lines, mimicking two fractures. Arrows are highlighting the malunion site and the step off of the proximal articular surface. The scaphoid fracture is being pried apart and opened like a clam shell, demonstrating the dorsal (D) and volar (V) fracture fragments. Note that the screws appear as small circles because they are passing from a dorsal to a volar position. The functional recovery of the operated wrists was reported to be good with an average return to work at 21 days following surgery. The study demonstrated the utility of arthroscopy, which aided the fracture reduction in 67 displaced fractures in addition to the 10 humpback deformities. Radiographic signs of arthritis in the radioscaphoid joint were more common in the surgically treated group (3/14) than in the conservative group (2/21). The clinical implication of this study is that their first choice of treatment for nondisplaced or minimally displaced scaphoid waist fractures is cast immobilization. For patients for whom a quick return to work or sport activities is of great importance, arthroscopic-assisted screw fixation was offered. They make the point that displacement and instability are often used interchangeably when referring to scaphoid waist fractures, but it is worthwhile to distinguish movement of the fracture fragments with gentle manipulation (instability) from fracture fragments that are out of position (displacement). At the scaphoid waist, displaced fractures are almost always unstable, but unstable fractures are not always displaced. Arthroscopic instability was diagnosed if the fracture fragments could be moved with gentle manipulation of the bone by applying external pressure on the distal pole of the scaphoid, by deviating the wrist in radial and ulnar directions, or by inserting a probe between the fracture fragments. Arthroscopy revealed 38 unstable fractures (movement between fracture fragments; 66%), 27 of which were also displaced. All arthroscopically determined displaced fractures were unstable, and 11 of the 31 arthroscopically determined nondisplaced fractures were unstable. There was a significant correlation between radiographic comminution (more than two fracture fragments) and arthroscopically determined displacement and instability. They also make the point, however, that given the fact that over 90% of radiologically nondisplaced scaphoid waist fractures heal with cast immobilization, instability may not be a risk factor for nonunion. These soft-tissue injuries negatively impacted the outcomes following treatment for the scaphoid fracture. The factors affecting outcome after non-vascular bone grafting and internal fixation for nonunion of the scaphoid. Management of displaced fractures of the waist of the scaphoid: meta-analyses of comparative studies. The effect of delayed treatment on clinical and radiological effects of anterior wedge grafting for non-union of scaphoid fractures. Screw fixation of scaphoid fractures: a biomechanical assessment of screw length and screw augmentation. Comparison of screw trajectory on stability of oblique scaphoid fractures: a mechanical study. A comparative analysis of the accuracy, diagnostic uncertainty and cost of imaging modalities in suspected scaphoid fractures. Using computed tomography to assist with diagnosis of avascular necrosis complicating chronic scaphoid nonunion. Clinical and radiological outcome of cast immobilisation versus surgical treatment of acute scaphoid fractures at a mean follow-up of 93 months. Cast immobilization with and without immobilization of the thumb for nondisplaced and minimally displaced scaphoid waist fractures: a multicenter, randomized, controlled trial. Comparison of short and long thumb-spica casts for nondisplaced fractures of the carpal scaphoid. Determining scaphoid waist fracture union by conventional radiographic examination: an analysis of reliability and validity. Multiplanar reconstruction computed tomography for diagnosis of scaphoid waist fracture union: a prospective cohort analysis of accuracy and precision. Central screw placement in percutaneous screw scaphoid fixation: a cadaveric comparison of proximal and distal techniques. Percutaneous internal fixation of selected scaphoid nonunions with an arthroscopically assisted dorsal approach. Anatomic placement of the Herbert-Whipple screw in scaphoid fractures: a cadaver study. Percutaneous fixation of the scaphoid through a dorsal approach: an anatomic study. Acute coronal plane scaphoid fracture and scapholunate dissociation from an axial load: a case report. Volarly displaced transscaphoid, translunate, transtriquetrum fracture of the carpus: case report. Retrospective review of 234 scaphoid fractures and nonunions treated with arthroscopy for union and complications. Conservative treatment versus arthroscopic-assisted screw fixation of scaphoid waist fractures-a randomized trial with minimum 4-year follow-up. Factors associated with arthroscopically determined scaphoid fracture displacement and instability. Results of arthroscopic reduction and percutaneous fixation for acute displaced scaphoid fractures. The incidence of intrinsic and extrinsic ligament injuries in scaphoid waist fractures. There is a bimodal distribution with high-energy fractures occurring in younger people, mostly males, and low-energy fractures occurring in older persons, mostly females. The articulation of the ulnar head to the radius is not congruent, with the radius of curvature of the shallow sigmoid notch being slightly greater than that of the convexity of the ulna head.

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Patients who have undergone small- and moderate-volume liposuction are discharged on the day of surgery after they void on their own; they are encouraged to ambulate and to maintain proper hydration with a liberal intake of oral fluids symptoms gallstones generic 75mg endep. Most of these patients can usually wear the garments 24 to 48 hours later medications 3605 generic 75mg endep fast delivery, when most of the fluid drainage has subsided medications keppra order endep 10 mg visa. Despite a regimen of diet and exercise medicine upset stomach discount 75 mg endep overnight delivery, she was still unhappy with the residual fatty deposits in her lower abdomen medicine 19th century safe 50 mg endep, hips symptoms underactive thyroid purchase generic endep canada, and thighs. The patient was 5 feet 6 inches tall and weighed 135 pounds at the time of her surgery. The aspirate volume for the thighs and hips was 4450 cc, and the total V aspirate volume was 5200 cc. The thighs and buttocks display the more athletic appearance that the patient desired. The physical findings regarding her extremities included moderate lipodystrophy of her thighs, hips, and infragluteal areas, with some minor dimpling in the lateral thighs and the infragluteal areas. The patient was 5 feet 7 inches tall and weighed 162 pounds at the time of her surgery. The aspirate volume was 7100 cc for the thighs and hips and 500 cc for the arms; the total V aspirate volume was 10,500 cc. At 1 year after the procedure, she displays good skin retraction and significantly improved aesthetic contours of her thighs and hips. The physical examination revealed moderate skin tone, significant lipodystrophy of the hip areas, moderate generalized lipodystrophy of the abdomen, and moderate well-defined lipodystrophy of the lateral thighs and the infragluteal rolls. The patient was 5 feet 4 inches tall and weighed 142 pounds at the time of her surgery. The superior inner thigh area of lipodystrophy has been corrected, and the contour of the buttock is improved. There has been good postoperative skin retraction, and the lower abdominal dimpling has been corrected. She was particularly concerned about excess fatty deposits in her lateral and upper medial thighs. The patient was 5 feet 6 inches tall and 130 pounds, which was close to her ideal body weight. She is seen 4 months postoperatively with very good skin retraction and a much more athletic appearance to her thighs and buttocks. Maintaining the natural lateral convexity of the thigh provided her with an aesthetically pleasing and feminine contour of the lower extremities. The physical examination revealed significant lipodystrophy of the lateral thighs, infragluteal areas, anterior thighs, and upper medial thighs. There was noticeable skin dimpling in the lateral buttock area, lateral thighs, and posterior thighs. The patient was 5 feet 7 inches tall and weighed 147 pounds at the time of surgery. In addition, she sought to improve the contour of her arms, which she felt had not responded to her regimen of diet and exercise. The physical examination revealed modest generalized lipodystrophy of the abdomen with poor skin tone as well as moderate lipodystrophy of the arms with moderate skin tone. The patient did not wish to undergo an open procedure for the arm contouring; she was willing to accept the limited improvement of the arm volume and contour that would occur with lipoplasty. She is seen 4 months after the procedure with a significant reduction in the volume of her posterior arms and improved contour. The physical examination of the upper extremities revealed significant lipodystrophy of the arms with moderate skin tone. The patient was 5 feet 5 inches tall and weighed 152 pounds at the time of surgery. The patient was discharged the following morning after tolerating oral fluids well and voiding on her own. At 4 months after surgery, the patient had a significantly smaller arm circumference with improved contour and good skin retraction. Overextraction, underextraction, and irregular extraction are by far the most common complications encountered with liposuction of the extremities. The use of an intraoperative flow sheet that documents infusion and aspiration volumes for each area is essential for keeping track of extraction volumes. Undercorrection responds well to revisionary extraction, and overcorrection often requires fat grafting. Skin irregularities resulting from liposuction often respond well to external ultrasound treatments. Skin loss is rare after liposuction, but it can be severe enough to require skin grafting. One of the most important contributing factors is smoking, which, when combined with extensive superficial liposuction, can lead to devascularization of the skin, with ensuing necrosis. The use of greater volumes of wetting solution dispersed within the tissues and the introduction of the current generation of ultrasound devices have contributed to thermal damage becoming a rare complication. It results from hemosiderin deposits, is usually self-limiting, and disappears spontaneously 4 to 6 months after surgery. Treatment with external ultrasonic massage devices has been helpful for decreasing the time until the hyperpigmentation resolves, and it has also been used to successfully treat irregularities after liposuction. The lymphatic massage component of the device is helpful for decreasing postoperative edema after liposuction procedures. Dysesthesias are the result of the demyelination of peripheral nerves as a result of their exposure to excessive ultrasonic energy; they are a rare and transient phenomenon today with the third-generation devices. One should nevertheless avoid major peripheral nerve contact with any ultrasonic probe. For example, the access incisions made for arm contouring should be placed on the radial side of the elbow to avoid the close proximity of the ultrasonic probe to the ulnar nerve. When applying ultrasonic energy to the arm tissues, the surgeon should avoid extending the probe into the axilla, where it would also be in close proximity to the nerves in that region. However, friction from the suction cannulas and thermal damage from the ultrasonic probes are factors that contribute to the poor healing of these incisions. Using a small-diameter cannula and applying a wet towel at the incision site helps to minimize friction. Critical Decisions and Operative Nuances Circumferential contouring of the extremities yields a more harmonious aesthetic result compared with "spot" fat extraction. When contouring the lower extremities, the surgeon should not dissociate the hips and buttocks from the thighs. The use of small-diameter cannulas provides greater precision, particularly during aspiration of superficial fat. A radial side incision at the elbow should be made when contouring the arm to avoid injury to the ulnar nerve. The postoperative use of foam, compression garments, lymphatic drainage, external ultrasonic massage, and skin-moisturizing regimens can optimize outcomes and decrease recovery time. Aesthetic body contouring of the posterior trunk and buttocks using third generation pulsed solid probe internal ultrasound-assisted lipoplasty. Comparison of blood loss in suction-assisted lipoplasty and thirdgeneration ultrasound-assisted lipoplasty. Comparative analysis of blood loss in suction-assisted lipoplasty and third-generation internal ultrasound-assisted lipoplasty. The effects of nonfocused external ultrasound on tissue temperature and adipocyte morphology. A national survey of complications associated with suction lipectomy: a comparative study. Liposuction for body contouring continues to grow in popularity and technological sophistication. Surgeons performing liposuction continue to gain a better understanding of fat anatomy and fluid management, along with improved instrumentation and technique. There is no doubt that, in the hands of a properly trained and experienced provider, liposuction is safer and more predictable than ever before. Most well-trained and experienced surgeons have been able to work well within the boundaries that this dose-response curve dictates. Most of these proposed technologies use thermal energy-ultrasonic, laser, or radiofrequency. Not only have these technologies so far failed to reduce complications from liposuction, but also they have added an unintended, second dose-response curve, creating contour deformities based on the thermal load imparted to the tissues. Among other factors, such as the power, energy type, and how it is applied, the treatment time itself becomes the main contributor to creating contour deformities. Definitions Revision liposuction and secondary liposuction procedures differ in a few important ways. Revision liposuction refers to a repeat operation usually performed by the same surgeon to improve the first result or to fix something left undone or not optimally performed during the first procedure. Secondary liposuction refers to procedures that are often, but not always, performed by a different surgeon, and are more extensive in nature than a revision procedure. Another distinction between revision and secondary liposuction is temporal: secondary procedures are usually not performed less than 1 year after the initial procedure, even if they are performed by the same surgeon. This chapter will mainly discuss secondary liposuction procedures, although much of the information will pertain to both revision and secondary liposuction, because both of these types of procedures are categorized as repeat procedures. Reasons for a Repeat Procedure Repeat procedures are performed for a variety of reasons, including unsatisfactory results or the need for further improvement. Frequently, a liposuction patient simply seeks further reduction to an area that was already treated, either because of weight gain or because he or she was dissatisfied with the amount or distribution of the liposuction. A typical candidate for a repeat procedure is a patient who underwent "spot" liposuction, usually of the upper or lower abdomen only. Because the entire abdominal or truncal unit was not contoured comprehensively, the patient is dissatisfied with the remaining area or areas of adiposity and therefore wants a more comprehensive procedure secondarily. More commonly, however, dissatisfied patients seek a secondary procedure to correct one or many contour deformities that resulted from an initial liposuction procedure. These contour deformities include overall skin waviness, hills and valleys, strange contours, and outright divots and depressions. In addition to these contour deformities, many patients have skin damage in the form of hemosiderin deposition, pigmentary changes, and scarring from thermal or avulsive liposuction methods. Internal scarring is seen as an unnatural static and/or dynamic appearance of the area, with tethering, tightness, and worsening appearance with positional changes or skin tension. External scarring is usually only seen with thermal methods of liposuction in which there were entry site burns, or even internal burns so severe that the overlying skin was burned and scarred. Note the irregular appearance of the skin surface and stained appearance of the skin from hemosiderin deposition, which is commonly seen after thermal liposuction. Note the severe skin irregularities with uneven skin retraction, deep and superficial contour deformities, and unnatural appearance of all of the treated areas. Note the irregular appearance of the skin surface, contour deformities, and asymmetrical collapse of the gluteal folds, giving an aged and unattractive appearance to the buttocks. Note the severe residual surface scarring, skin creases, uneven skin retraction, hemosiderin deposition, and contour deformities. She also underwent multiple external radiofrequency treatments without improvement. Note the uneven skin contraction, deep contour deformities, areas of dense scarring, and overall skin surface irregularities. Difficulties Inherent in Repeat (Revision or Secondary) Liposuction the feasibility of liposuction itself is based on the premise that there is a relatively low-resistance, "harvestable" subcutaneous adipose tissue layer between the higherresistance planes of the overlying superficial fat and dermis above and the underlying musculoskeletal structures below. This differential in resistance between these planes is what allows a cannula to easily pass through and stay in the target fat layer. Thus liposuction works, because fat is less dense and easier to traverse, disrupt, and remove than the tissues that surround it. Once a liposuction procedure has been performed, this treatable tissue layer is scarred, adherent, or even obliterated, making navigation and fat extraction more difficult and potentially more dangerous, even for experienced surgeons. For example, in a primary liposuction procedure, significant resistance encountered at the cannula tip is generally a sign that the cannula should be redirected. In a revision or secondary procedure, this is not necessarily the case, so the surgeon must be able to discern whether the resistance is coming from a vital structure or from fibrotic subcutaneous tissue that remains from a previous procedure. This loss of differential resistance seen in repeat liposuction procedures is the main reason these procedures frequently result in problems, such as skin "end hits," resulting from the natural tendency for the surgeon to redirect superficially, preferring to err here rather than in deeper structures. The loss of this low-resistance plane can also result in potentially fatal (and likely underreported) abdominal perforation or damage to other deeper structures. Many competent and experienced body contouring surgeons do not perform repeat liposuction procedures at all, perhaps wisely. As plastic surgeons, we typically strive for beautiful results that "do no harm" to the patient, but when considering repeat liposuction, we are faced with two nearly universal truths that distinguish these procedures from most other revision plastic surgery procedures: first, the result will never be as good as the result that could have been obtained from an optimally performed primary liposuction procedure; and second, the risk of significant or serious injury is much higher and outside the usual scope of a primary liposuction procedure. Despite these and other difficulties faced in repeat liposuction procedures, revision and secondary body contouring with liposuction can be very gratifying and successful for patients and their surgeons when the appropriate expectations, approach, care, and techniques are applied. I perform a somewhat "alternative" approach to the typical techniques that have been proposed for repeat liposuction. This technique can help many patients who otherwise have not previously had much hope of regaining a more normal or natural appearance. There are still liposuction patients with deformities from primary procedures who are not good candidates for repeat procedures; the majority of this subset of patients will have undergone thermal methods of liposuction. Repeat procedures are also associated with complications that are different from those commonly seen after primary liposuction procedures. In repeat procedures, the differential in resistance between the intended and unintended planes is narrowed, sometimes even eliminated. As outlined previously, this difficulty in navigating through scarred, adherent subcutaneous tissues increases the risk of damage to the skin and deeper structures, resulting in a potentially life-threatening complication. These procedures also take more time to perform, which is another factor that increases overall risk. Obviously, in such an environment, fat extraction is more challenging, and smoothness and uniformity are more difficult to achieve.

A second included studies where the subjects imagined performing the motor sequences medicine games discount endep 75mg otc, again without specific instructions as how to go about doing it medications and breastfeeding buy endep 25 mg with amex. The third included studies in which explicit instructions were given to subjects to use kinesthetic images medications ritalin discount endep online master card. The fourth included studies also involving explicit instructions to the subjects to use their visual imagery symptoms zyrtec overdose buy generic endep 50 mg on-line. Finally medications known to cause weight gain endep 50 mg line, the fifth class included studies of "laterality judgments" where the subjects were shown body parts in different orientations and were asked to judge whether the shown limb was to the left or the right symptoms youre pregnant generic endep 75 mg otc. This task involving mental rotation would be expected to engage both visual and kinesthetic images. The areas consistently activated across studies in each class are presented in Table 15. From the preceding summary of the results, it is again clear that all five forms of motor imagery, including the explicitly visual form, entail activation of some components or hubs of the motor execution network. It is also entirely possible that the pattern of consistent activation that characterizes each form of imagery in this sample of studies is what in fact mediates each kind. But, once again, what accounts for the fact that we do not confuse our percepts with our mental images still remains unclear since the most likely factor-that is, absence of M1 activation-was not consistent. In fact, activation from M1 was reported in 22 out of the 122 experiments reported in the 75 papers analyzed. Therefore, it may be concluded that a possible paucity of M1 activation accounts for the fact that we do not confuse our mental images with our actual actions. However, the force of that conclusion ought to be tempered in view of more recent work employing multivoxel pattern analysis (Pilgramm et al. Equally tentative must be the answer to the question of what differentiates imagining that we are performing a motor act from imagining someone else performing it. These patterns are sufficiently distinct, yet their reliability and validity must await the verdict of similar future investigations since activation patterns found for these two forms of imagery (Daselaar, Porat, Huijbers, & Pennartz, 2010; Lorey et al. Meanwhile, one may be justified in concluding that motor imagery as opposed to imagery of static stimuli does require parts of the motor network-a conclusion that supports the notion of embodied cognition. The Sense of Body Ownership and Its Neuronal Mechanism In the first section of the previous chapter, we commented on attempts to identify the neuronal mechanism of the sense of agency, that is, the conviction that we are the authors of our own actions. But, in addition to experiencing this sense of agency, Net works of Motor Cognition 325 we also realize that we are the owners of our bodies and our body parts. The independence of these two related yet distinct experiences (and concepts) becomes clear in the case of involuntary or reflexive movements (Gallagher, 2000). The difference between the concepts of agency and ownership also becomes clear in cases of neurological disorders like "anarchic hand syndrome" because in such cases the subjects feel that their hands act against their conscious intentions; that is, they recognize that they are not the agents of the action, but, at the same time, they also realize that it is their body part that is performing it (della Sala et al. Similarly, the distinction is clear in schizophrenia, where the sense of agency may be missing yet the sense of ownership remains. The dissociation between agency and ownership can also be studied experimentally by inducing subjects to misattribute their sense of ownership of a body part to objects that they do not "own. In the first section of the previous chapter, it was argued that this conclusion, in so far as the feeling of agency goes, is a mere metaphysical assertion without empirical foundation. Whether the feeling of ownership is also an illusion because it can be made illusory under certain circumstances is another metaphysical question well beyond the scope of this Handbook. As to whether (illusory or not) it has neuronal correlates is a question that we answered in the affirmative in the chapter on basic concepts (or, rather, we have assumed that it has an affirmative answer). But whether such correlates have been found is a question that will be answered shortly. A well-known example of dissociation of the concepts of agency and ownership is the one of the "rubber hand illusion". The problem of the neuronal mechanisms responsible for the sense of ownership motivated a number of ambitious yet perfectly legitimate projects involving functional neuroimaging. Although these projects have produced only tentative solutions to the issue under consideration, they are worth reviewing because they point to the potential of the neuroimaging methods to address the neuronal correlates of subtle aspects of human experience. The researchers suggested that the neuronal activity in the premotor cortex is associated with the subjective experience that the artificial hand belongs to oneself (Ehrsson et al. Along similar lines, Farrer and Frith studied the neuronal correlates of two kinds of attribution: experiencing oneself as the cause of an action. During this experiment, the participants used a joystick to drive a circle along a T-shaped path. The participants were told that either they or the experimenter would drive the circle. In the first condition, participants were told that the circle was driven by themselves and they were aware of this fact; thus they mentally attributed the visualized action to themselves. In the second condition, they were requested to perform the movement but they were aware that the experimenter was driving the circle; thus they attributed the visualized action seen on the screen to her. The results showed that being aware of causing an action was associated with activation in the anterior insula, whereas being aware of not causing the action and attributing it to another person was associated with activation in the inferior parietal cortex (Farrer & Frith, 2002). In this study, subjects opened and closed their hands continuously while they watched their action on a video screen online. Conversely, the activation of the putamen was negatively correlated with the temporal delay. One cannot avoid noticing that although these two studies examine the same phenomenon, they result in clearly different activation patterns. Leube and associates suggest that this discrepancy may depend on the modality under investigation: whereas Farrer and associates (2003) modulated spatial features of the visual information, Leube and associates (2003) varied the temporal ones. They undoubtedly have heuristic value, but they are no substitute for replications of the experiments that would settle this and every other of the dozens issues that remain unsettled. Simulated actions in the first and in the third person perspectives share common representations. Visuospatial reorienting signals in the human temporoparietal junction are independent of response selection. The out-of-body experience: Disturbed self-processing at the temporo-parietal junction. Neural mechanisms of empathy in humans: A relay from neural systems for imitation to limbic areas. Timecourse of mirror and counter-mirror effects measured with transcranial magnetic stimulation. Selective attention modulates inferior frontal gyrus activity during action observation. Modality-specific and modality-independent components of the human imagery system. The role of the right temporoparietal junction in social interaction: How low-level computational processes contribute to meta-cognition. The neural correlates of velocity processing during the observation of a biological effector in the parietal and premotor cortex. What activates the human mirror neuron system during observation of artificial movements: Bottom-up visual features or top-down intentions Experiencing oneself vs another person as being the cause of an action: the neural correlates of the experience of agency. Human cortical representations for reaching: Mirror neurons for execution, observation, and imagery. Observed, executed, and imagined action representations can be decoded from ventral and dorsal areas. The anthropomorphic brain: the mirror neuron system responds to human and robotic actions. Activation of human primary motor cortex during action observation: A neuromagnetic study. Moving a rubber hand that feels like your own: A dissociation of ownership and agency. Neural systems shared by visual imagery and visual perception: A positron emission tomography study. The neural correlates of moral sensitivity: A functional magnetic resonance imaging investigation of basic and moral emotions. Observing complex action sequences: the role of the fronto-parietal mirror neuron system. Convergent evoked potential and cerebral blood flow evidence of taskspecific hemispheric differences. Motor imagery of hand actions: Decoding the content of motor imagery from brain activity in frontal and parietal motor areas. Neurophysiological mechanisms underlying the understanding and imitation of action. The functional role of the parieto-frontal mirror circuit: Interpretations and misinterpretations. Visual memory, visual imagery, and visual recognition of large patterns by the human brain: Functional anatomy by positron emission tomography. Modulation of cortical excitability during action observation: A transcranial magnetic stimulation study. The rubber hand illusion revisited: Visuotactile integration and self-attribution. Neural signatures of body ownership: A sensory network for bodily self-consciousness. Visual features of an observed agent do not modulate human brain activity during action observation. Papanicolaou and Marina Kilintari Abstract Among the "higher" functions, language and its cerebral networks is the most intensively explored through behavioral or clinical studies and, more recently, through functional neuroimaging. From the former studies, several models (only partially congruent) have emerged during the past three centuries regarding the organization and topography of the brain mechanisms of the acoustic, phonological, semantic, syntactic, and pragmatic operations in which psycholinguists have divided the language function. The main task of this chapter is to extract from the vast functional neuroimaging literature of language reliable evidence that would be used to disconfirm the various hypotheses comprising the current language models. Most of these hypotheses concern the anatomical structures that could be considered nodes or hubs of the neuronal networks mediating the above-mentioned linguistic operations. Using the same criteria, the authors present neuroimaging evidence relevant to the issue of the neuronal mediation of sign languages, reading, and dyslexia. Key Words: language networks, language, functional neuroimaging, acoustic operations, phonological operations, semantic operations, syntactic operations, neuronal networks, sign language, reading Hypotheses About Language Networks Derived from Behavioral and Clinical Observations How, precisely, meaningful speech is produced and how heard speech acquires its meaning, remain unresolved mysteries and their cerebral mechanism obscure. Linguistic analysis, however, and observations of the effects of local brain lesions during the past two centuries have resulted in some understanding of particular features of these mechanisms. It has been realized, for example, that language most likely consists of more-or-less distinct operations, acoustic, phonological, semantic, and syntactic, each associated with its own neuronal network, which networks are nevertheless interconnected; that some of these networks, unlike those mediating nonlinguistic perception and action, are lateralized to the left "dominant" hemisphere in most people and that reading and sign language are most likely mediated by the same mechanisms as those of natural speech. These notions have cohered into a "classical" model the main features of which are as follows. This feature of the early acoustic and phonological analysis of speech has been supported by lesion studies (Luria, 1970; Rauschecker & Scott, 2009; Scott, Blank, Rosen, & Wise, 2000;) and behavioral data (see. This view has been widely supported by clinical data indicating that lesions in those areas appear to disrupt comprehension of both words and sentences (Bogen & Bogen, 1976; Geschwind, 1972; Lhermitte & Gautier, 1969; Marie, 1906; Naeser, Helm-Estabrooks, Haas, Auerbach, & Srinivasan, 1987; Turken & Dronkers 2011). In view of new clinical evidence, however, this classical model has been challenged on several points. But what has emerged from those challenges is not a new model but a set of often conflicting hypotheses sharing only the notion that the classical division of language processes into perceptual, mediated by the posterior hub of the language network, and productive, mediated by the anterior hub, is no longer tenable; that both hubs participate in both sets of processes and that each is specialized for different aspects of each set. The particular hypotheses differ, most likely due to the fact that the lesion data from which they have been derived are highly variable in terms of severity, extent, and other aspects and lead to different conclusions. Fortunately, though, these hypotheses can be, and many have been, tested through neuroimaging. To begin with, recovery of language following aphasic stroke appears to be accomplished through the involvement of the right hemisphere, suggesting that the right hemisphere may have the capacity for mediating many language operations including phonological ones (see. For example, such patients can match pictures to words and their errors are due to confusion with phonemically and not semantically similar distractor items (Buchman, Garron, Trost-Cardamone, Wichter, & Schwartz, 1986; Miceli, Gainotti, Caltagirone, & Masullo, 1980; Poeppel, 2001; Rogalsky & Hickok, 2011; Rogalsky, Pitt, Hillis, & Hickok, 2008), as can patients with their right hemisphere anesthetized during the Wada procedure (Hickok et al. This possibility has become a feature of the "dual route" model of Hickok and Poeppel (see. Dementia studies point to the same conclusion with respect to the causes of semantic deficits. The next significant deviation from the classical model concerns the mechanisms of semantic operations. Yet that newly defined region is not considered sufficient for the comprehension of word (and sentence) meaning. According to the more recent notions, the process of speech comprehension unfolds as follows: following extraction of auditory features of the word heard (which may be mediated by the primary auditory cortex), the phonetic features are computed by the phonological mechanisms in either the left or both in the right and the left auditory cortex. The product of this analysis is a set of neuronal signals that constitutes the phonological "word-form" (see. This is one scenario as to how word comprehension ought to activate the auditory cortex bilaterally (or unilaterally, depending on particular models) and the vast but technically inaccessible region of stored meanings. Moreover, mainly on the basis of behavioral data, a theory known as the "analysis by synthesis" theory of speech perception (see Fowler, Shankweiler, & Studdert-Kennedy, 2016; Liberman et al. Finally, spontaneous discourse requires activation of frontal regions (but which ones remains a matter of pure speculation) plus the semantic circuits of word meaning. Moreover, the perception of linguistic prosody is said to be mediated by both hemispheres, whereas affective prosody by predominantly right hemisphere networks (Witterman, van Ijzendoorn, van de Velde, van Heuven, & Schiller, 2011), but what structures these networks may involve is, once again, a matter of speculation that it is for functional Net works of Language 333 neuroimaging to settle. There is also considerable agreement regarding the mechanisms of perception of prosody that characterizes most natural verbal communication. Lesion evidence points to the possibility that such mechanisms are lateralized in the right hemisphere, although their precise location in it has not be identified (see.