Showing papers on "Temporal cortex published in 1978"

Changes in brain cholinesterases in senile dementia of alzheimer type

Abstract: Acetyl- and butyryl-cholinesterase activities have been measured biochemically in normal brain tissue, in senile dementia of Alzheimer type and in mental disorders without Alzheimer-type abnormalities. Acetylcholinesterase was significantly reduced and butyrylcholinesterase significantly increased, compared with the normal, in the hippocampus and temporal cortex of the Alzheimer cases. No significant enzyme changes were seen in the other diseases investigated including multi-infarct dementia, schizophrenia and depression. There was no correlation between age and acetylcholinesterase activity, but a significant positive correlation between the butyrylcholinesterase activities with increasing age (60-90 years) was found in the hippocampus. The possible connection between cholinergic system pathology and these cholinesterase abnormalities in Alzheimer dementia is discussed.

The neuroanatomy of amnesia. A critique of the hippocampal memory hypothesis.

Abstract: The discovery that medial temporal lobe lesions produce amnesia in humans if the lesion extends sufficiently far posteriorly to include the hippocampus forms the keystone of the hippocampal memory hypothesis. Strong supporting evidence comes from the occurrence of mammillary body disease in Korsakoff's psychosis. Disease of the posterior cerebral artery confirmed the observations on the medial temporal lobectomies by showing that pathology in the ventromedial quadrant of the temporal lobe produces amnesia. The occasional piece of contradictory evidence was sufficiently ambiguous to be dismissed or re-interpreted. Although the contradictory evidence that emerged from animal research created severe difficulties, opinion had crystallized on the matter to the degree that the data were unable to force rejection of the hippocampal memory hypothesis. This necessarily led to the conclusion that the animal model is a poor one: either the human hippocampus is unique with respect to memory or the tests which are used in animals do not tap the same mnemonic processes that are impaired by the human lesions. Both these arguments are nearly impossible to refute. The brain of every species is different and there is no way in which monkeys and humans can be tested under identical conditions. There has never been much enthusiasm for the suggestion that the human hippocampus is so different from other animals that this uniqueness could account for the apparent differences between the behavioural effects of human and animal hippocampal lesions. However, many experimenters have devised clever tests of the possibility that the problem is in the animal behavioural measures. Given sufficient circularity of reasoning, the project must necessarily eventually be successful. The argument is that if the usual tests of learning and memory that are used with animals are not disrupted by hippocampal lesions, then these are not tests of the kinds of learning and memory defects displayed by human amnestics. One has only to search for tasks that are disrupted by hippocampal lesions in animals, and these then must tap the same memory processes that are disrupted by the human lesions. The possibility has rarely been seriously considered that it might be damage to some structure in the ventromedial quadrant of the temporal lobe other than the hippocampus that is responsible for the amnesia. The amygdala and entorhinal area have been ruled out by both the human and animal data. However, the temporal stem is a likely possibility. Its position makes it vulnerable to the surgical approach which was used in human medial temporal lobectomies, and its damage in animals produces deficits in learning and retention. When medial temporal lesions were made in monkeys in the same way that they were made in humans, inadvertent damage to the temporal stem occurred along with the intended amygdaloid and hippocampal injury. Symptoms characteristic of damage to the temporal cortex resulted from these lesions and they were probably caused by the damage to the stem...

The medial geniculate body of the tree shrew, Tupaia glis. II. Connections with the neocortex.

Abstract: In this study the temporal cortex of the tree shrew was subdivided on the basis of cytoarchitectonic criteria, and the connections of each subdivision with the thalamus and midbrain were analyzed with retrograde and anterograde techniques The results indicate that, with one exception, each subdivision of the medial geniculate body projects to a separate cortical area The primary auditory cortex receives projections from the ventral nucleus Surrounding the primary cortex are at least five additional cytoarchitectonically distinct areas which receive projections from the remaining medial geniculate subdivisions The evidence suggests that there is very little overlap in the projections from each of these geniculate subdivisions An exception is the projection of the caudal nucleus of the medial division This subdivision apparently projects to most, if not all, of the cortical target of the medial geniculate body Although the cortical projections of the caudal nucleus overlap those of the other medial geniculate subdivisions, the laminar distribution of its terminations in cortex is different The caudal nucleus projects primarily to layer VI whereas the other subdivisions of the medial geniculate body project primarily to layer IV and the adjacent part of layer III Anterograde techniques were also used to study the projections from the cortex back to the thalamus and to the midbrain The projections to the thalamus precisely reciprocate the thalamocortical connections The projections to the midbrain are to the same areas which the preceding study (Oliver and Hall, '78) showed give rise to ascending projections to the medial geniculate body An exception is the central nucleus of the inferior colliculus which apparently does not receive a projection from the temporal cortex

Inferior temporal lesions do not impair discrimination of rotated patterns in monkeys.

Abstract: Ablation of inferior temporal cortex in the rhesus monkey produces a visual discrimination learning deficit. The severity of this deficit has often been found to be a function of task difficulty. This report concerns a type of visual discrimination problem that, although difficult, is not sensitive to inferior temporal lesions. Monkeys with anterior, posterior, and complete inferior temporal lesions were repeatedly unimpaired or only slightly impaired in learning to discriminate a pattern from the same pattern rotated 90 degrees or 180 degrees; yet they were very severely impaired in learning equally or more difficult discriminations of two different patterns. This demonstration that discrimination of orientation of patterns is relatively spared after inferior temporal lesions helps specify the pattern-recognition processes that require inferior temporal cortex.

Regional Cerebral Blood Flow in Aphasia

Abstract: • Regional cerebral blood flow (rCBF) was studied in 13 aphasic patients with left hemisphere lesions, using the intracarotid xenon 133 injection method and a 254-detector gamma camera system. The rCBF was measured during rest and during various function tests, including a simple speech test. In motor (nonfluent) aphasia, the rCBF method showed areas of cortical dysfunction that always included the lower part of the rolandic area while Broca's area was not consistently affected. In sensory (fluent) aphasia, the superior-posterior temporal cortex was involved in all cases. In global aphasia, the abnormalities included both regions consistently involved in the other types of aphasia. The 133 Xe injection method for mapping abnormalities relevant for localizing the cortical speech areas was superior to the classical neuroradiological methods in that several cases failed to show any relevant lesion whatsoever. This is probably related to the functional nature of the rCBF method: subnormal flow values and lack of the normal flow increase during function tests apparently may disclose functionally inactivated but structurally intact cortex.

Hemiparkinsonism with infarction of the ipsilateral substantia nigra

Abstract: An elderly man suffering from dementia associated with hypertension developed right-sided parkinsonism marked by rigidity and flexion. At autopsy the brain showed generalized vascular changes chiefly in the white matter, diffuse plaque and neurofibrillary tangle formation in the temporal cortex, and a discrete gliotic scar in the right substantia nigra. Hemiparkinsonism with a strictly unilateral lesion confined to the substantia nigra has, to our knowledge, not been described before, and the fact that it was ipsilateral adds to its theoretical interest.

Neostigmine Activated Epileptiform Discharge in the Amygdala: Electrographie‐Behavioral Correlations

Abstract: SUMMARY This investigation was carried out to test the hypothesis that amygdaloid epileptiform activity is due to cholinergic hyperactivity. It was designed to study the underlying physiopathology of, and to act as an experimental model for, psychomotor epilepsy. Neostigmine was injected in-tracerebrally into the amygdala of the cebus monkey with chronically implanted “chemitrodes” fitted with EEG recording electrodes. The injections were made in the basal amygdaloid nucleus which normally shows very high acetylcholinesterase (AChE) enzymatic activity in histochemical preparations. Neostigmine injection resulted in very high amplitude spike activity in the amygdala only. Other brain areas, including the neighboring temporal cortex, did not show any marked EEG changes. In the first day or two, these EEG changes were associated with myoclonus localized in the ipsilateral muscles of facial expression and also associated with masticatory seizures. Subsequently the animal became aggressive and remained so several months after the injection of neostigmine. The EEG changes continued for approximately 6 weeks. Intramuscular injections of atropine diminished the amplitude of the epileptiform EEG discharges and modified slightly the animal's behavior. RESUME Ces experiences ont ete entreprises dans le but de tester l'hypothese suivant laquelle l'activite epilep-tique de l'amygdala resulte d' une hyperactivity cholinergique. Elles ont egalement pour but d‘etudier la physiopathologie correspondante et de servir ainsi de modele experimental de l’epilepsie psychomotrice. La neostigmine est injectde dans l' amygdala du singe cebusal'aide de “chemitrodes” implantees et accouplees a des electrodes d'enregistrement EEG. Les injections sont faites dans le noyau amygdaloidien basal qui montre normalement sur les preparations histochimiques une activite enzymatique acetyl-cholinesterasique (AChE) tres elevee. Ces injections provoquent une activite de pointe de tres grande amplitude limitee a l'amygdala. Les autres aires cerd-brales, y compris le cortex temporal voisin, ne mont-rent aucune modification EEG importante. Durant les un ou deux premiers jours, ces modifications EEG sont associees a un myoclonus localise aux muscles faciaux ipsilatdraux et a des crises masticatoires. Consecutivement l'animal devient agressif et le de-meure pendant plusieurs mois. Les modifications EEG persistent pendant environ six semaines. L'injection intramusculaire d'atropine diminue l'amplitude des decharges dpileptiques sur I'EEG et modifie legere-ment le comportement de l'animal. RESUMEN Esta investigacion se ha llevado a cabo para com-probar si la hipotesis de que la actividad epileptiforme de la amigdala es debida a una hiperactividad colinergica, es correcta. Se ha disenado para estudiar la fisiopatologia subyacente de la epilepsia psicomotora y para que se utilice corao modelo experimental. Se in-yect6 neostigmina en el interior de la amigdala del mono cebus con “detectores quimicos” implantados cr6nicamente y acoplados a electrodos con registro electroencefalografico. Las inyecciones se realizaron en el nucleo amigdaloideo basal, que habitualmente muestra una elevada actividad enzimatica de la acetilcolinesterasa (AChE) en las preparaciones histoqui-micas. La inyeccion de neostigmina produjo puntas de gran voltaje limitadas a la amigdala. Otras zonas cere-brales, incluyendo la corteza temporal vecina, no mostraron alteraciones notables en el EEG. En el primer o segundo dia, los cambios del EEG se asociaron a mioclonias localizadas en los musculos de la expresi6n facial ipsilateral unidas a convulsiones masticatorias. Tras la inyecci6n de neostigmina los animales mostraron una agresividad que persisti6 durante varios meses. Las alteraciones electroencef-alograficas se continuaron observando durante unas seis semanas. La inyeccion intramuscular de atropina disminuy6 la amplitud de las descargas epileptiformes del EEG y modifico ligeramente el comportamiento del animal. ZUSAMMENFASSUNG Die Untersuchung wurde durchgefuhrt, um die Hypothese zu prufen, das die epileptiforme Aktivitat des Amygdalon Folge cholinergischer Hyperaktivitat ist. Der Versuch wurde so geplant, das die zugrunde-liegende Physiopathologie der psychomotorischen Epilepsie untersucht werden konnte und das er als ex-perimentelles Modell fur die psychomotorische Epilepsie dienen konnte. Neostigmin wurde intrazerebral in das Amygdalon des Cebusaffen injiziert, der chronisch im-plantierte “Chemitroden” erhalten hatte, die mit EEG-Elektroden ausgestattet wurden. Die Injektionen er-folgten in die basalen Anteile des Nucleus amygdaleus, die normalerweise eine sehr hohe Acetylcholinesterase (AChE) und Enzymaktivitat in histochemischen Praparationen aufwiesen. Neostigmin-Injektionen riefen eine sehr hochamplitudige Spike-Aktivitat nur im Amygdalon hervor. Andere Hirnareale einschlieBlich des be-nachbarten temporalen Cortex zeigten keine deutlichen EEG-Veranderungen. In den ersten ein oder zwei Tagen waren die EEG-Veranderungen von einem Myoklonus begleitet, der sich auf die ipsilateralen Gesichtsmuskeln beschrankt und von mastikatorischen Symptomen begleitet wurde. In der Folgezeit wurde das Tier aggressiv und bliebes bis mehrere Monate nach der Injektion von Neostigmin. Die EEG-Veranderungen bestanden etwa6 Wochen. Die intramuskulare Injektion von Atropin ver-minderte die Amplitude der epileptiformen Entladungen im EEG und modifizierte ein wenig das Verhalten des Tieres.

[Piecewise Fourier analysis of images and the role of the occipital, temporal and parietal cortex in visual perception].

Abstract: On the basis of previously published data, a neuronal scheme of organization of the visual perception in the cerebral cortex, is suggested. An idea of neuronal module is introduced: a cylinder of cortical neurons whose receptive fields are directed towards the same area of the visual field and respond to different spatial frequencies and orientations. A system of overlapping modules is able of piece--wise Fourier--description of portions of the image. The modules of the Clare--Bishop area are composed of receptive fields of different size. Owing to that each neuron of the module projects inhibitory influence upon other neurons, the module acts as a filter picking out the texture. Therefore, the modules of the Clare--Bishop area single out and supply Fourier--description of subimages, the latters being characterized by the same local spectrum within their own limits. The lower portion of temporal cortex performs a rough identification of subimages and images with the aid of systems of learning neurons. The parietal cortex conforms the description from temporal cortex to the complete description in the modules of occipital cortex, thus performing the transition from an image to a concrete picture.

Electrophysiological analysis of corticopontine connections

Abstract: In acute experiments on cats anesthetized with pentobarbital and chloralose, the method of recording focal responses was used to study projections of various parts of the orbito-frontal and basal temporal cortex and also of the hippocampus in the region of the pons. Different formations of the fronto-basal zones of the neocortex were shown to have local projections in the rostral zones of the pons and relatively diffuse projections in its caudal zones. Projections of the hippocampus in structures of the pons are less well marked than those of the fronto-basal zones of the neocortex and their focal responses are more diffuse in character. Representation of all the structures studied is found only in the nuclei of the gray matter of the pons. The orbito-insular zone of the orbito-frontal cortex is not represented in the caudal zones of the reticular formation; the basal temporal cortex has no projection in the middle cerebellar peduncles.

Unitary responses of the hypothalamic nuclei to stimulation of the frontobasal neocortex

Abstract: Unitary responses in the hypothalamic nuclei to stimulation of the frontobasal zones of the cortex (proreal, orbito-insular, and basal temporal regions) were studied. Cortico-thalamic connections were found to possess definite topical organization: the orbito-frontal zones of the cortex have a more marked effect on unit activity of the hypothalamic nuclei than the basal temporal cortex. Antidromic activation, during stimulation of a particular region of the cortex, of neurons excited orthodromically by stimulation of another cortical structure, enables a number of neuronal circuits functioning within the forebrain to be distinguished. The first circuit includes the orbital gyrus, preoptic zone, and proreal gyrus. The second circuit has the same cortical components as the first, but its relay in the hypothalamus takes place in the region of the mamillary bodies. The third circuit is represented by the basal temporal cortex, lateral hypothalamus, and prefrontal cortex.

Interaction between retinal and visual cortical fibers in several subcortical visual centers of the rat

Abstract: Szentagothai (ed.), Modern Trends in Ne~romorphology, Symposia Biol. Hung., Budapest, Akad. Kiado (1965), pp. 251-276. Szentagothai, J., Arkh. Anat., No. 2, 3-21 (1971). Vvedenskii, N. E., Excitation, Inhibition, and Narcosis [in Russian], SPb (1903). Woolsey, T., "Organization of the temporal cortex," in: Theory of the Connections of Sensory Systems [Russian translation], Moscow (1964). Zhukova, G. I., "Neural composition of the motor cortex of mammals," Candidate's Dissertation, Moscow (1950).

[Effect of propyl-2-pentene-2-oic acid on GABA levels in different regions of mouse brain].

Abstract: An elevation in cerebral GABA level (65%) is observed after administration of an anticonvulsant, sodium propyl 2-pentene-2 oate, a branched chain fatty acid, comformationally restricted GABA analogue, competitive inhibitor of GABA-T in regard to GABA. The concentration of GABA increases in some regions i.e. substantia nigra, frontal and temporal cortex, cerebellum and olfactory bulbs. The GABA level remains unchanged in caudate nucleus, hippocampus and occipital cortex. Results are discussed comparatively to the effect of sodium n-dipropylacetate.

EEG activity of symmetrical points of the cerebral cortex during unilateral cooling of the temporal neocortex in cats

Abstract: A study of ten alert cats has shown that inactivation with cold of the temporal neocortex elicits a sharp drop in EEG activity in all the examined points of the homonymous hemisphere, which actually points to a temporary switching off of its function. At the same time a unilateral switching off of the temporal area brings about an increase in EEG activity of the contralateral hemisphere. Functional asymmetry sets in not only in the system of the auditory analyser, but also in other sensory systems. Systematic cold switching off of the temporal cortex in one hemisphere results in a reduced contrast in the EEG of the brain symmetrical regions.

Mechanism of formation of complexes of epileptic activity in the cerebral cortex under the influence of a determinant focus

Abstract: Experiments on cats anesthetized with pentobarbital showed that when a hyperactive focus with a high level of excitation is formed in the temporal cortex and a series of foci with lower levels of excitation is formed in other parts of the neocortex, a functional complex with coordinated activity is created and is controlled by the activity of the hyperactive focus. The latter plays the role of a determinant structure. Depression of the determinant focus leads to disintegration of the epileptic complex. The nature of the foci is unimportant as regards the realization of these relationships: Both determinant and dependent foci could be created with the aid of strychnine and penicillin, which disturb different types of inhibition. The results confirm the general concept of the role of determinant structures in the activity of the nervous system.