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Background: Different strategies have been used to study the fiber tract anatomy of the human brain in vivo and ex vivo. Nevertheless, the ideal method to study white matter anatomy has yet to be determined because it should integrate information obtained from multiple sources., Objective: We developed an anatomic method in cadaveric specimens to study the central core of the cerebrum combining traditional white matter dissection with high-resolution 7-T magnetic resonance imaging (MRI) of the same specimen coregistered using a neuronavigation system., Methods: Ten cerebral hemispheres were prepared using the traditional Klingler technique. Before dissection, a structural ultrahigh magnetic field 7-T MRI study was performed on each hemisphere specifically prepared with surface fiducials for neuronavigation. The dissection was then performed from the medial hemispheric surface using the classic white fiber dissection technique. During each step of the dissection, the correlation between the anatomic findings and the 7-T MRI was evaluated with the neuronavigation system., Results: The anatomic study was divided in 2 stages: diencephalic and limbic. The diencephalic stage included epithalamic, thalamic, hypothalamic, and subthalamic components. The limbic stage consisted of extending the dissection to complete the Papez circuit. The detailed information given by the combination of both methods allowed us to identify and validate the position of fibers that may be difficult to appreciate and dissect (ie, the medial forebrain bundle)., Conclusion: The correlation of high-definition 7-T MRI and the white matter dissection technique with neuronavigation significantly improves the understanding of the structural connections in complex areas of the human cerebrum.

Animals face different threats; to survive, they have to anticipate how to react or how to avoid these. It has already been shown in teleosts that selected regions in the telencephalon, i.e., the medial pallium, are involved in avoidance learning strategies. No such study exists for any chondrichthyan. In nature, an avoidance reaction may vary, ranging from a ‘freeze’ reaction to a startling response and quick escape. This study investigated whether elasmobranchs (Chiloscylliumgriseum and C. punctatum) can be conditioned in an aversive classical conditioning paradigm. Upon successful conditioning, the dorsal, medial and lateral pallium were removed (group 1) and performance tested again. In a second group, the same operation was performed prior to training. While conditioning was successful in individuals of both groups, no escape responses were observed. Post-operative performance was assessed and compared between individual and groups to reveal if the neural substrates governing avoidance behavior or tasks learned in a classical conditioning paradigm are located within the telencephalon, as has been shown for teleosts such as goldfish.

Background and Importance: State-of-the-art treatment of anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) often proves ineffective. Both disorders have common features, and anterior capsulotomy is a last-resort treatment for OCD. We document the effect of bilateral anterior capsulotomy in a patient with comorbid AN and OCD., Clinical Presentation: A 38-year-old woman with life-threatening, chronic, treatment-refractory AN and OCD underwent anterior capsulotomy. Psychiatric and neuropsychological evaluations at baseline and at follow-up document the severity and progress of the case. Bilateral anterior capsulotomy resulted in normalization of eating pattern and weight and a significant decrease of food-related and overall obsessive-compulsive symptoms. Psychiatric evaluations and exposure to food cues confirmed the clinical improvement that was evident immediately after surgery and sustained at 3-month follow-up., Conclusion: This case report suggests that bilateral anterior capsulotomy can be a therapeutic option for patients with comorbid AN and OCD. However, a well-controlled study is warranted.

The human insular cortex, or the lobus insularis, is considered the developmentally most primitive lobe of the telencephalon. Covered by an overlying cortical lid, the insula has functions that are distinct from yet related to those of the adjacent temporal lobe and deep limbic structures. In the first part of this paper the authors outline the development of the human insula, including the cellular heterogeneity comprising the various parts of the insular lobe. Using the understanding gained from the development of the insula they then address implications of insular development for cortical development and connection as well as for tumorigenesis and tumor spread from the insula to other cortical structures, most notably the temporal lobe. An understanding of cortico-insular development and interconnection allows for both a better understanding of insular pathology and also facilitates planning of resection of cortico-insular gliomas to avoid damage to eloquent structures.

We determined the effect of an H1 receptor antagonist on the functional recovery of Carassius auratus submitted to telencephalic ablation. Five days after surgery the fish underwent a spatial-choice learning paradigm test. The fish, weighing 6-12 g, were divided into four groups: telencephalic ablation (A) or sham lesion (S) and saline (SAL) or chlorpheniramine (CPA, ip, 16 mg/kg). For eight consecutive days each animal was trained individually in sessions separated by 24 h (alternate days). Training trials (T1-T8) consisted of finding the food in one of the feeders, which were randomly blocked for each subject. Animals received an intraperitoneal injection of SAL or CPA 10 min after the training trials. The time spent by the animals in each group to find the food (latency) was analyzed separately at T1 and T8 by the Kruskal-Wallis test, followed by the Student Newman-Keuls test. At T1 the latencies (mean +/- SEM) of the A-SAL (586.3 +/- 13.6) and A-CPA (600 +/- 0) groups were significantly longer than those of the S-SAL (226.14 +/- 61.15) and S-CPA (356.33 +/- 68.8) groups. At T8, the latencies of the A-CPA group (510.11 +/- 62.2) remained higher than those of the other groups, all of which showed significantly shorter latencies (A-SAL = 301.91 +/- 78.32; S-CPA = 191.58 +/- 73.03; S-SAL = 90.28 +/- 41) compared with T1. These results support evidence that training can lead to functional recovery of spatial-choice learning in telencephalonless fish and also that the antagonist of the H1 receptor impairs it.

Young naive domestic chicks readily attack green insects and avoid insects painted red but show no discrimination of the same colours when applied to fruit-like objects, a discrimination that has been depicted as context-dependent preference. To study the neural representation of such preference we performed bilateral telencephalectomy on 1-day-old domestic chicks and tested them on an unlearned prey discrimination paradigm. Here we show that following complete decerebration, young domestic chicks preferentially peck at red fruit versus red insects and tend to choose green insects over green fruit indistinguishably from unoperated chicks. The present study provides the first direct evidence that sophisticated context-dependent, unlearned colour preference is processed by subtelencephalic areas of an amniote species.

The present study investigated the involvement of H(1) histaminegic receptor on the acquisition of inhibitory avoidance in Carassius auratus submitted to telencephalic ablation. The fish were submitted to telencephalic ablation 5 days before the experiment. The inhibitory avoidance procedure included 1 day for habituation, 3 days for training composed of 3 trials each (1st day: T1, T2, T3; 2nd day: 2T1, 2T2, 2T3; 3rd day: 3T1, 3T2, 3T3) and 1 day for test. On training days, the fish were placed in a white compartment, after 30 s the door was opened. When the fish crossed to a black compartment, a weight was dropped (aversive stimuli). Immediately after the third trial, on training days, the fish received, intraperitoneally, one of the pharmacological treatments (saline (N = 20), 8 (N = 12) or 16 (N = 13) microg/g chlorpheniramine, CPA). On the test day, the time to cross to the black compartment was determined. The latency of the saline group increased significantly only on the 3rd trial of the 2nd training day (mean +/- SEM, T1 (50.40 +/- 11.69), 2T3 (226.05 +/- 25.01); ANOVA: P = 0.0249, Dunn test: P < 0.05). The group that received 8 microg/g CPA showed increased latencies from the 2nd training day until the test day (T1 (53.08 +/- 17.17), 2T2 (197.75 +/- 35.02), test (220.08 +/- 30.98); ANOVA: P = 0.0022, Dunn test: P < 0.05)). These results indicate that CPA had a facilitating effect on memory. We suggest that the fish submitted to telencephalic ablation were able to learn due to the local circuits of the mesencephalon and/or diencephalon and that CPA interferes in these circuits, probably due an anxiolytic-like effect.

This work investigated the effect of the H1 receptor blockade in the forebrain of ablated Carassius auratus in a simple stimulus-response learning task using a T-maze test with positive reinforcement. The goldfish were submitted to surgery for removal of both telencephalic lobes five days before beginning the experiment. A T-shaped glass aquarium was employed, with two feeders located at the extremities of the long arm. One of the two feeders was blocked. The experimental trials were performed in nine consecutive days. Each fish was individually placed in the short arm and confined there for thirty seconds, then it was allowed to swim through the aquarium to search for food for ten minutes (maximum period). Time to find food was analysed in seconds. Animals were injected intraperitoneally with chlorpheniramine (CPA) at 16 mg/kg of body weight or saline after every trial, ten minutes after being placed back in the home aquarium. The results show that all the training latencies of the A-SAL group were higher than the latencies of the S-SAL group. The S-SAL group had decreased latencies from the second trial on, while the S-CPA group showed decreased latencies after the fourth trial. The A-SAL group showed reduced latencies after the fifth trial, but the A-CPA group maintained the latencies throughout the experiment. This suggests that CPA impairs the consolidation of learning both on telencephalon ablated animals and in sham-operated ones through its action on mesencephalic structures of the brain and/or on the cerebellum in teleost fish.

A 49-year-old woman presented with a rare atypical growth pattern of meningioma without evidence of dural attachment manifesting as chronic headache associated with transient paresthesia and left motor disorders. On admission, neurological examination showed no abnormalities. Magnetic resonance (MR) imaging revealed a right temporo-parieto-occipital lesion, which appeared to involve the subdural space and filling the cortical sulci. The lesion caused peritumoral white matter edema. The tumor appeared hypointense on T(1)-weighted and hyperintense on T(2)-weighted MR images, with homogeneous enhancement after contrast administration. A biopsy of the lesion was performed. Histological examination indicated that the lesion was a meningioma. Intraparenchymal meningiomas should be considered in the differential diagnosis of intraaxial lesions in patients of any age.

Introduction: The use of neuroendoscopy has increased in the past 20 years. Despite an increase in the number of indications for use, novel adjuncts and modifications to existing endoscopes remain all but nonexistent. We introduce a robotic virtual endoscope with applications for neurosurgery that could serve as a novel step in the evolution of future endoscopic technologies., Methods: Over the past 8 years, we have worked on the construction of a prototype endoscope with three degrees of freedom that was designed to allow for enhanced safety while maximizing the benefits of virtual field rendition and robotic control. We have developed a prototype to examine a cerebral ventricular model in vitro that functions via either a direct video- or computer-based interface., Results: Assessment of viewing angulation with robotic feedback has verified the accuracy of the prototype. Models support the ability of the endoscope to localize regions identified via a software interface., Conclusion: The endoscope is a rigid virtual robotic endoscope that provides complete visual coverage of a three-dimensional space by controlling an adjustable viewing direction with three degrees of freedom.

Epidermoids occurring within the lateral ventricles are rare. At one time, they were regarded as anatomical curiosities. The lesions are of developmental aetiology, due to migration of epiblast inclusion at the time of formation of the cerebral vesicle. They are slow growing, and presentation is non-specific in the form of deteriorating mental functions. Generally seen in the fifth decade, but they have also been observed in the paediatric age group. MRI is suggestive of a cystic lesion, and is confirmed to be a typical epidermoid within the lateral ventricle at operation, often having a connection to the midline through the choroidal fissure. The cysts should be excised with no additional morbidity. Histopathology reveals typical stratified squamous epithelium.

Objective: Optimal surgical management in lateral ventricle tumors remains controversial. We conducted a retrospective study of patients with these lesions treated with a surgical strategy on the basis of tumor origin: primary or secondary ventricular and associated transependymal development., Methods: A total of 72 patients underwent surgery for lateral ventricle tumors. The mean patient age was 39 years (range, 6 mo to 78 yr). Raised intracranial pressure occurred in 53% of patients, followed by mental disturbances or psychiatric symptoms (32%) and motor deficits (21%). The transcortical approach was used in 44 patients, and an interhemispheric approach was used in 28 patients; a transcallosal approach was used in 16 patients, and a parasplenial approach was used in 12 patients. Neuropsychological tests were performed in selected patients., Results: Total resection was performed in 82% of patients. Sixty-five percent of tumors were benign and low-grade tumors. There was no surgical mortality, and the morbidity rate was 11%. Postoperative epilepsy (5.9%) was significantly increased in the transcortical group. The mean follow-up period was 55 months; 59% of patients achieved good recovery and moderate disability. In postoperative neuropsychological testing sessions, deficits in verbal memory were observed in six patients (8%). Final morbidity correlated well with preoperative clinical condition and pathological diagnosis., Conclusion: Lateral ventricle tumors can be treated best by careful selection of the approach according to tumor origin and development. Overall, the transcallosal approach is preferred, but in patients with transependymal growth or large primary or secondary ventricular tumors, the transcortical is a better option.

Objective: The objective of this study was to determine whether an angiographically proven rate of saccular intracranial aneurysm occlusion after surgical clipping suggests that postoperative angiography should continue to be used routinely or should be supplanted by intraoperative angiography. These data also should establish a basis for comparing surgery with new endovascular methods of treatment., Methods: During a 3.5-year period, a consecutive series of 622 patients (955 aneurysms, 808 of which were surgically clipped) who underwent postoperative angiography were studied retrospectively. This series comprised 493 ruptured and 315 unruptured aneurysms., Results: Complete aneurysm closure was achieved in 88% of aneurysms, a neck remnant was discovered in 9%, and a fundus remnant was revealed in 3%. Of 493 ruptured aneurysms, 86% were completely occluded. Of 315 unruptured aneurysms, 91% were completely occluded. The results for clipping of complex aneurysms, i.e., posterior circulation or large to giant aneurysms, were significantly inferior to those for small and anterior circulation aneurysms. In one-third of the large and giant aneurysms, a part of the base was left intentionally because of calcifications or strong wall or to prevent occlusion of any branches. In the series, a significant 5% complication rate of major vessel occlusion was detected., Conclusion: Our retrospective analysis revealed that ruptured, posterior circulation, and large/giant aneurysms are more prone to incomplete clipping. Therefore, these aneurysms require postoperative if not intraoperative evaluation with angiography. Many clippings of anterior circulation aneurysms experience unexpected failures, which suggests that intraoperative angiography could be beneficial. This series, which has no selection bias, can be used as a basis to compare the results of other series reporting surgical or endovascular treatment.

Transplantation of neural progenitors or stem cells is a most useful tool to investigate the relative contribution of cell-autonomous mechanisms and environmental cues in the regulation of cell specification and differentiation during CNS development. To assess the capability of neocortical progenitor cells to integrate into foreign brain regions, here we examined the fate of precursor cells isolated from the dorsal telencephalon of E12 ss-actin-EGFP transgenic mouse embryos after heterotopic/heterochronic transplantation to the E16 rat brain in utero. Our observations show that donor cells were able to penetrate, survive and produce mature cell types into wide regions of the host CNS. Namely, EGFP-positive cells acquired site-specific neuronal identities in many telencephalic regions, including neocortex, hippocampus, olfactory bulb and corpus striatum. In contrast, incorporation into more caudal sites was much less efficient. A fraction of donor cells formed large aggregates that remained segregated from the host milieu. Such aggregates contained mature neurons and glia, including some EGFP-negative elements of host origin, and developed the complex organization of the mature nervous tissue. On the other hand, transplanted cells that engrafted in the parenchyma of extratelencephalic regions predominantly generated glial types. The few neurons failed to acquire obvious site-specific phenotypic traits and did not integrate into the local host architecture. Altogether, our observations indicate that E12 neocortical progenitors are already committed towards regional identities and are unable to modify their phenotypic choices when exposed to heterotopic environmental conditions along different rostro-caudal domains of the embryonic CNS.

The role of the telencephalon in the shoaling behavior of the goldfish, Carassius auratus, was investigated. Experiments were carried out in a tank divided into three compartments. Subjects were introduced into the center compartment of the tank. In the activity phase, subjects swam alone, and swimming distance was used as an index of activity. In the shoaling behavior phase, a stimulus fish was introduced into one of the side compartments, and the time spent near the side compartment by the subject was used as index of shoaling behavior. After these measurements were made, visual and motor abilities were examined using the optomotor response. Subjects then received surgery and the same procedure was repeated. In Experiment 1, the effects of total ablation of the telencephalon and a section of the olfactory tract (OlT) were examined. The ablation group exhibited reduced activity and shoaling behavior compared with the sham and OlT group. In Experiment 2, the role of the dorsal part of the telencephalon was examined after damaging the dorsomedial and dorsolateral telencephalon. Lesions in either portion had no effect and no simple visual or motor deficits were seen. These results suggest that the ventral part of the telencephalon mediates shoaling behavior.

The identification of Nocardia transvalensis, an unusual and probably underrecognized cause of nocardial infection, is clinically significant because of this species' resistance to aminoglycosides, a standard antinocardial therapy. Diagnosis requires analytic methods available predominately in reference laboratories. We report a case of disseminated infection with N transvalensis with primary pulmonary involvement and subsequent development of brain abscesses, and review the literature to date. Familiarity with the epidemiology, pathologic findings, and clinical significance of this and other unusual Nocardia species may increase early identification and antibiotic susceptibility testing in cases of nocardial infection.

The purpose of this study was to elucidate the biological significance and the possibility of intracerebral grafting of neuroepithelial stem cells derived from the mesencephalic neural plate. Immunohistological studies of embryonic day 10.5 (E10.5) Wister rats revealed strong nestin expression in the mesencephalic part of the neural plate. Mesencephalic neural plates removed from E10.5 rats were processed to either tissue or cell dissociation culture. They were cultured in vitro under various conditions and were analyzed 7 days after the primary culture. When they were cultured as a tissue, cell proliferation and differentiation into neurons extending long neurites were obvious in a serum-free medium, in a medium containing 3% serum, and in a medium containing 20 ng/ml epidermal growth factor. On the other hand, in a medium containing 10 ng/ml basic fibroblast growth factor (bFGF), both vigorous cell proliferation and sphere formation were recognized. Furthermore, marked neurite growth was rarely seen in this culture. When they were plated in a dissociation culture, cell proliferation and neurosphere generation were also recognized only in a medium containing bFGF, depending on the initial cell concentration. The spheres, generated 7 days after the primary cell culture, were positively stained by nestin. These data suggested that bFGF was able to amplify the stem cell population present in the mesencephalic neural plate derived from early embryos. This might make it possible to obtain a large number of stem cells as donor material for neural transplantation on demand.

We report a case of a 31 year-old woman who in 1991 presented a clinical history of headaches, nausea and vomiting. CT scan showed a right frontotemporal meningioma. The first operation achieved a macroscopically complete resection. The tumour was histologically classified as a transitional meningioma. There were recurrences of the intracranial meningioma in 1994, 1996, 1997 and 1998. These recurrences were accompanied by differentiation to atypical and anaplastic meningioma. In all of these operations, a macroscopically complete resection of the tumour was performed. In 1996 adjuvant radiation therapy was given. In 1998 therapy with bromocriptine was adopted. In April 1999, the patient presented with lumbosacral pain associated with L5 bilateral sciatica. MRI showed a gadolinium enhancing mass lesion at L5-S1 level. Complete tumour resection was performed. The histological findings were the same as in 1998. In December 1999 the patient presented with perineal pain and MRI showed a L4 and S3 recurrence and the tumour was resected. The histological findings were those of a malignant meningioma. In February 2000 an intracranial recurrence was detected and operated on. The histological diagnosis was malignant meningioma. A review of the literature was undertake and is discussed.

The cerebellum seems to be one of the structures responsible for early neurological improvement after cerebral hemispherectomy and its consequent deficits. Considered as an accessory brain, the cerebellum may constitute a neurobiological substrate for the recovery of such extensive cortical and subcortical lesions. It may compensate for the injury by structural remodeling and plasticity. The authors observed that, indeed, rats submitted to contralateral hemicerebellectomy before cerebral hemispherectomy do not recover as well as those submitted to hemicerebellectomy 2 weeks after cerebral hemispherectomy., (Copyright 2002 S. Karger AG, Basel)

During the past six years 623 cases of coenurosis (gid) in sheep have been treated surgically. Cysts were removed successfully from 573 of them (92 per cent) and 517 (83 per cent) were able to return to their flocks, although 36 showed no clinical improvement In 37 cases, the cyst could not be localised, and postmortem examinations showed that in nine cases the cyst was in the brainstem, and in 28 cases it was in the cerebellum. Fifty-six cases deteriorated gradually after surgery and in these cases more than one cyst was found postmortem. Thirteen cases died during surgery.

We examined the neural bases of song preferences in female zebra finches (Taeniopygia guttata). Females performed more courtship displays in response to conspecific songs than to heterospecific songs. Following electrolytic lesion to the HVc (sometimes referred to as high vocal center), females maintained normal song preferences. However, following lesion to cHV (caudal hyperstriatum ventrale, an auditory area) females performed courtship displays at high rates in response to both conspecific and heterospecific song. Thus cHV, but not HVc, must be intact for female zebra finches to exhibit normal song preferences. Differences between this study and those showing HVc lesions disrupting song preferences in female canaries (Serinus canaria) indicate interspecific variation in the function of HVc in female songbirds.

The avian hippocampal formation (Hf) plays an important role in spatial memory for food storing. Here we examined the effects of excitotoxic lesions of the Hf and subsequent neural transplantation on a one-trial associative memory task in zebra finches. The results showed (1) that small ibotenic acid lesions of the dorsal Hf of zebra finches produced significant spatial memory impairments compared with controls, sham-lesioned birds, and prelesion performance; and (2) that Hf-lesioned birds given transplants of embryonic hippocampal (H) tissue, but not those given transplants of embryonic anterior telencephalon (AT) tissue, showed a significant reversal of the performance deficits on the spatial memory task. Lesioned-only birds and lesioned birds given H or AT transplants that did not survive did not show behavioral improvement. Sham-lesioned and untreated control birds maintained good performance throughout the experiment. The H and AT transplants were found to be growing partially within the Hf and partially within the underlying ventricle. The transplants appeared healthy and contained neurons with beaded and unbeaded fibers (shown by immunohistochemistry with antibodies to parvalbumin, substance P, and a 200 kDa neurofilament protein). Blood vessels and erythrocytes were also present within the transplants. The results show that neural transplants can survive within the bird brain and that small lesions of the Hf produce significant spatial memory deficits that can only be reversed by surviving homologous H transplants, and not by heterologous telencephalon transplants.

Habituation to sound stimulation was analyzed in terms of the functional role of the telencephalon in learning. Sixteen pigeons were exposed to 1000-Hz, 83-dB, 1-s sound (stimulus A) at 30-s intervals until there was habituation of the exploratory and pre-exploratory responses. The learning criterion was 10 trials without the occurrence of these responses. Twenty-four hours after habituation to stimulus A the birds were tested with a 500-Hz, 85-dB, 1-s sound (stimulus B). On the day following habituation to stimulus B, the birds of the experimental group (N = 8) suffered ablation of the telencephalon and the birds of the control group (N = 8) had sham surgery. Retesting with the same sequence of procedures was carried out 10 days after surgery. In the POST-lesion situation there was a decrease of the number of habituation trials to stimulus A (P less than 0.01) and to stimulus B (P less than 0.05) by experimental pigeons compared to the PRE-lesions situation. The data suggest an interaction of a facilitatory effect of the lesion and long-term learning effects.

The directional selectivity of units within the nucleus of the basal optic root (nBOR) of the accessory optic system (AOS) was studied before and after lesions of the visual telencephalon (visual Wulst) in urethane-anesthetized pigeons. In intact pigeons, most nBOR units preferred upward motion with a temporal component or downward motion with a nasal component. The ipsilateral and bilateral telencephalic lesions generated a dramatic reduction in the number of cells with optimal responses to upward motion. The overall distribution of preferred directions was still bimodal following ipsilateral or bilateral Wulst lesions, with most units showing best responses to a straight temporal or to downward-nasal directions. The contralateral Wulst lesions produced, instead, a marked reduction in downward preferences. The nBOR units which were studied in these cases showed mainly upward-temporal and upward-nasal responses. These data suggest an involvement of the visual Wulst in the determination of the directional selectivity of nBOR neurons in the pigeon. Specifically, the responses of nBOR units to upward motion appeared to depend on the integrity of the telencephalic descending systems which impinge, in both direct and indirect ways, upon that AOS nucleus. Taken together with data for the mammalian AOS, the present results indicate that nonretinal afferents to AOS nuclei have an important role in the functional organization of that subcortical visual pathway.

To investigate the relationship of age-related processes in the recovery of complex motor functions of the limbs, a variety of neurobehavioral assessments were applied to cats with either neonatal (n = 9) or adult (n = 11) removal of the entire left hemitelencephalon (hemispherectomy). Neonatal-lesioned kittens showed no paw preference in reaching for a manipulandum between 5 and 8 weeks of age; thereafter they developed a preference (5.6%) for the unimpaired left limb which persisted throughout adulthood. Adult-lesioned cats showed a significantly greater left bias (13.9%) than neonatal-lesioned cats and they exhibited more abnormal movements and postures when reaching with the impaired limb. Exercising the impaired limb, was effective in reversing the paw preference bias in all lesioned cats. To master a food retrieval task with the impaired limb, adult-lesioned cats required more trials than the neonatal-lesioned group, extensive food deprivation and at least 1 month of postsurgical recovery. However, after mastering this task all cats could continue to perform it indefinitely in their home cages. In a paw print analysis of locomotion, only adult-lesioned cats showed abnormalities including splayed paws, decreased stride length, and adduction of the right hind limb. The results support the 'Kennard Principle' of enhanced recovery following neonatal vs late brain lesions for the present complex motor patterns and are interpreted in the context of neural plasticity and anatomical reorganization during development.

The perceptual completion phenomenon refers to seeing a figure as complete when part of it falls in a blind area of the visual field. This phenomenon and the conditions for its occurrence were examined in three different situations: over the retinal blind spot, across the midline of the visual field in commissurotomized patients, and in the blind visual field in hemianopic patients. Responses of complete perception were obtained in each of the three conditions, but they were not all the result of a genuine perceptual completion process. Reports of vision over the retinal blind spot qualified as genuine perceptual completion. In the other two situations, reports suggestive of completion could be entirely eliminated in all but one hemianopic patient by manipulating parameters inherently involved in the evaluation of perceptual completion. The nature of perception, the characteristics and properties of the experimental task and stimuli, the mode of response, the patient's mental status, and eccentric eye fixation, all contributed towards reports of complete perception for reasons other than a process of completing the missing information. Evidence of completion was found in one patient who could see more distinctly in his affected field with bilateral stimulation than with stimulation of the affected field alone. The results suggest that perceptual completion in the hemianopic field is not a common phenomenon and that reports of complete perception are determined by many factors, not all related to seeing more than is objectively available. The results also indicate that the hemianopic defect does not function as an extended blind spot. Possible mechanisms underlying perceptual completion over the blind spot and the hemianopic field are suggested.

Inhibition of ADH-secretion and transient water diuresis was observed as acute effects of radio-frequency lesions in the septal region of goats. The water diuresis was not compensated for by drinking and therefore rapidly induced pronounced hypernatremia and hypovolemia. The development of hypovolemia was accompanied by a rise in plasma renin activity. Lesions of the same kind, but extending into the preoptic region near the medial portion of the supraoptic nuclei induced the inability to excrete excessive water characteristic of SIADH. Determinations of plasma arginine vasopressin suggested that the lesions causing SIADH did not produce any noticeable increase in basic ADH-secretion. The results suggest that impulses from juxtaventricular receptors regulating ADH-release and water intake to a considerable extent are transmitted via the septal region, and that elimination of this impulse traffic is sufficient to turn water balance to the negative side. However, reflex volumetric inhibition of the ADH-secretion does not seem to be mediated by pathways passing through the septal region.

Visual intensity difference thresholds were studied before and after telencephalic lesions in pigeons. Subjects with visual Wulst lesions showed initial postoperative threshold elevations that represented losses of 19%-49% of their preoperative sensory capacity. This initial loss was correlated with the extent of damage to three components of the visual Wulst: nucleus intercalatus hyperstriati accessorii, hyperstriatum intercalatus suprema, and hyperstriatum accessorium. The damage to hyperstriatum dorsale, another component of the visual Wulst, made no contribution to the initial deficit. The sensory capacity of all but one pigeon improved as a result of postoperative retraining.

There is evidence that inhibitory avoidance learning is still possible after removal of the telencephalic forebrain. However, it is not known whether subtelencephalic storage of such a conditioned response takes place when the brain is intact. To investigate this possibility, rats received one training trial in the "up-hill avoidance" task, and 8 h later the entire forebrain except the hypothalamus was bilaterally ablated. When tested 24 h later, the decerebrate rats still exhibited the learned response, demonstrating a transfer of the conditioned response from the intact to the postlesion state. This result indicates that memory-storage for this avoidance task takes place, at least in part, subtelencephalically.

The telencephalon was removed unilaterally in rats. In addition, the forebrain of the other hemisphere was isolated from its brain stem by a precollicular transverse cut. This preparation was then tested for self-stimulation via electrodes implanted in the region of the lateral hypothalamus and medial forebrain bundle (LH-MFB) of either hemisphere. Self-stimulation was found to be intact in both hemispheres. Possible pathways connecting the LH-MFB region of one hemisphere to the contralateral diencephalon were also investigated in the bilaterally detelencephalized rat. The technique of retrograde transport of horseradish peroxidase was used for this purpose. Some fibers from the LH-MFB of one hemisphere were found to decussate to the other hemisphere by way of the thalamic commissure. The supraoptic decussation as well as diffusely organized interdiencephalic connections provide additional routes for interhemispheric LH-MFB projections.

A prospective and randomized trial has been performed in order to evaluate combined modality therapy in patients with astrocytomas grade 3 and 4. Follow-up information is available on 244 patients. One half of the series received radiation therapy twice a week (40.00 Gy/5 weeks), the other half five times a week (50.00 Gy/5 weeks). Misonidazole 1.2 g/m2 was given orally to one half of the patients in the first radiation treatment group 3 1/2 to 4 hours before the treatment. The other half received placebo. The second radiation treatment group was also divided in two halves, one receiving 0.48 g/m2 misonidazole and the other placebo 3 1/2 to 4 hours before radiation. The randomization also included a subdivision of the material into eight groups of which four were given CCNU and four no chemotherapy, beginning 3 months after operation. The dose of CCNU was 120 mg/m2 body surface every 6 weeks. All eight treatment groups showed practically identical periods of median survival, and no statistically significant differences were observed with regard to performance status, side effects, or complications. Another dosage and timing of misonidazole administration in relation to the irradiation schedule, and a consideration of effects of concomitant drugs like dexamethasone and phenytoin are discussed.

A serial-lesion technique was used to investigate interactions in visual processing between telencephalic components of the pigeon visual system. Pigeons were trained to discriminate pairs of stimuli that differed in color, intensity or pattern. After mastering the discrimination tasks, they were assigned to one of three groups. The first group (WI-EII) received lesions of the visual Wulst and were retested. After the discrimination tasks were again mastered, a second set of lesions was made, this time in the ectostriatum. The birds were tested once again after the second surgery. The second group (EI-WII), underwent the same sequence of events except that the order of the lesions was reversed. In the third group (E + W), lesions of both the visual Wulst and ectostriatum were made in a single operation, followed by retesting. The performance after the first lesion of the subjects in each of the two-stage lesion groups was typical of performance after such lesions; i.e. the birds with visual-Wulst lesions showed little or no impairment on any of the tasks, whereas the pigeons with ectostriatum lesions showed considerable deficits in intensity and pattern discrimination, which diminished after prolonged retraining. In contrast, the pigeons in the one-stage group (E + W) showed profound deficits that appeared to be permanent. The performance after the second operation of the WI-EII group was the same as that of pigeons with lesions of ectostriatum alone; i.e. destruction of ectostriatum first or second resulted in the same duration of impairment. The performance of the EI-WII group after its visual Wulst lesion, however, was similar to that observed in the E + W group. The results are interpreted as a reflection of parallel processing within the avian visual system; i.e. the presence of an intact tectofugal pathway may mask the effects of thalamofugal pathway interruption.

Two patients with epilepsy and large hemispheric lesions underwent section of the frontal fibres of the corpus callosum for the treatment of seizures refractory to medical treatment. A severely retarded girl of 18 had encephalotrigeminal angiomatosis (Sturge-Weber syndrome) with multiple daily absences, tonic-clonic, myoclonic, atonic and adversive seizures since infancy. All types of fits--with the exception of adversive seizures and rare tonic-clonic fits--disappeared after anterior callosotomy. Another moderately retarded girl of 18 had an old cystic lesion over the entire territory of the left middle cerebral artery. She had had right hemiplegia since infancy and frequent brief absences and massive myoclonus triggered by unexpected sensory stimuli since the age of six years. Following anterior callosotomy there was an almost complete disappearance of the absences and a marked reduction of her startle myoclonus. Frontal callosotomy is a useful procedure in epileptics with large hemispheric lesions and carries less risk than hemispherectomy or total commissurotomy.

Surgical management of refractory epilepsy has undergone many modifications since it was instituted for the treatment of post-traumatic seizures many decades ago. Localization of onset of all seizures to a single resectable area of brain by various noninvasive and invasive recording methods is a complicated and controversial area, but guidelines are available. Success is correlated with accurate location and complete resection of the focus. When this is accomplished, resective surgery for epilepsy can provide cure or over 95 per cent reduction in seizure frequency in 60 to 90 per cent of patients undergoing these procedures. Although most often applied to temporal lobe foci, resections may be done in any cerebral lobe in the dominant or nondominant hemisphere with appropriate modifications of the evaluation and surgical procedure. When patients have unlocalizable or unresectable foci, depending on their exact pattern of seizures, electrical abnormalities, and neurologic status, other procedures may be used for surgical control of seizures. These include hemispherectomy, corpus callosum section, or stereotaxic procedures. The risks of all evaluation and surgical approaches are well balanced by the benefits obtained in a large proportion of patients.

A hemispherectomy was performed on a girl of 20 because of progressively uncontrollable seizures and behavioral changes resulting from major head trauma at the age of five. Psychomotor development up to this age had been normal. Today she shows little impairment in higher nervous function depending on the ablated hemisphere. Left-sided motor performance has improved and sensory deficit is scant. There is no hemianopia and the right eye visual field is enlarged. Dichotic listening shows left ear preference and no lesion effect. These findings suggest that significant and positive adaptation may occur in mature brain.