Showing papers on "Temporal cortex published in 1981"

Widespread corticostriate projections from temporal cortex of the rhesus monkey.

Abstract: The corticostriate projections of temporal areas TA, TE, TF, TG, 35, and 28 were studied in the rhesus monkey with the use of autoradiography. Widespread projections were observed to rostral as well as caudal parts of the striatum for all areas except area 28. For example, areas TA and TG have sizable projections to the medial or periventricular part of the head of the caudate nucleus, as well as to the medial part of the tail of this structure and the dorsally adjacent putamen. Areas TE and TF also were observed to send strong projections to the head of the caudate nucleus. In addition, they project to the rostral putamen. Both have projections to the tail of the caudate nucleus and caudal putamen. The widespread distribution of temporostriate axons to the rostral striatum suggests strongly that previous silver impregnation studies have not only underestimated the strength of the temporal cortical contribution to the corticostriate system, but also failed to identify the major projection zone of temporostriate axon terminals. For example, while all temporal cortical areas contribute projections to an organized topography in the tail of the caudate nucleus and the ventrocaudal putamen, they were observed consistently to have larger projections to the head of the caudate nucleus and rostral putamen. These results add to a growing body of evidence which demonstrates the existence of widespread nonmotor cortical input to the basal ganglia, and an organization of this input far greater in complexity than that demonstrated by earlier suppressive silver impregnation methods.

Alterations in protein synthetic capability of nerve cells in Alzheimer's disease.

Abstract: Cytoplasmic RNA content, nuclear and nucleolar volume are all significantly reduced in nerve cells of the temporal cortex in cases of Alzheimer's disease, examined both at diagnostic craniotomy and post mortem, when compared with non=demented control cases of similar age. On average, at necropsy, all three parameters are equally reduced by about 40-50%, but in biopsy cases, nuclear volume is decreased by the greatest amount (43%), followed by nucleolar volume is decreased by the greatest amount (43%), followed by nucleolar volume (36%), and cytoplasmic RNA (26%). These findings indicate that a change in protein synthesis occurs daily in the course of Alzheimer's disease which may result from a primary alteration within the nuclear apparatus.

Early neurogenesis and synaptogenesis in cerebral cortex.

Abstract: Early cortical neurogenesis and synaptogenesis are discussed with reference to observations made in fetal and postnatal rat temporal cortex. Thymidine autoradiography was used to determine the time of origin of cortical neurons, particularly of layer I. Earliest neurons--CRs--form between FD 12 and 15, whereas the period of maximal formation of layer I neurons other than CRs is situated between FD 17 and FD 19. Neurons destined for the deepest part of layer VI begin to form at FD 13. Both types of early-forming neurons develop synaptic contacts by FD 16. From this stage onwards, the temporal cortex taken as a whole continuously contains synaptic contacts. However, a more detailed analysis shows that some at least of the early formed synapses are transitory: for example, the CRs, which receive dendritic synapses on FD 16 and somatic synapses on FD 17, apparently lose most--if not all--of these contacts towards the end of fetal life. Whereas CRs develop an important protein producing equipment during the neonatal period, younger neurons located in the same (first) layer form dendritic, somatic and somatofugal synapses.

Neurofibrillary pathology and protein synthetic capability in nerve cells in alzheimer's disease

Abstract: Mann D.M.A., Neary D., Yates, P.O., Lincoln J., Snowden J.S. & Stan-worth P. (1981) Neuropathology and Applied Neurobiology 7, 37–47 Neurofibrillary pathology and protein synthetic capability in nerve cells in Alzheimer's disease Nucleolar volume was measured in nerve cells of the temporal cortex in cases of Alzheimer's disease, obtained at both biopsy and autopsy. Measurements were made on those nerve cells containing neurofibrillary tangles and also on ones free of such changes. Results showed that nucleolar volume is significantly reduced, by at least 40%, in both tangle and non-tangle bearing cells, in both biopsy and autopsy cases, when compared with corresponding values from appropriate control cases. Furthermore, in the autopsy cases, nerve cell nucleolar volume was reduced by a further 30% in tangle bearing cells compared to non-tangle bearing neighbours. No such difference was noted in these cells in the biopsy cases. These findings imply that alterations in protein synthetic capability occur in nerve cells early in the course of Alzheimer's disease, and that this change is not, at least in these initial stages, related to accumulation of neurofibrillary material within the cell body, although later on such accumulation may result in added disruption of cell metabolism.

Multiple visual areas

Abstract: 1 Multiple Cortical Visual Areas: Visual Field Topography in the Cat.- 1. Introduction.- 2. Techniques.- 3. Visual Field Topography.- 3.1. Location of Cortical Visual Areas.- 3.2. Visual Field Transformations.- 3.3. Extent of Visual Field Represented.- 3.4. Areal Magnification Factor.- 4. Unexpected Findings.- 4.1. Asymmetry.- 4.2. Variability.- 4.3. Ability of Topographic Representations of the Visual Field to Define Functional Areas.- 5. Conclusion.- 6. Summary.- Acknowledgments.- References.- 2 Comparative Studies on The Visual Cortex.- 1. Introduction.- 2. Extension and Retinotopy of the Striate and Extrastriate Visual Areas in the Rat.- 3. Receptive Field Properties of Neurons in the.- Striate Cortex of the Rat.- 4. Striate-Extrastriate Corticocortical Connections.- in the Rat.- 5. Effects of Postnatal Enucleation of the Eye on the Striate-Extrastriate Connections in the Rat.- 6. Studies on the Visual Cortex of Other Rodents.- 7. Thalamic Afferents to Extrastriate Visual Areas in Rodents.- 8. Behavioral Studies on the Extrastriate Cortex of the Rat and Rabbit.- 9. Conclusions from Studies on the Rat.- 10. Cortical Connections from the Striate Cortex in the Rabbit.- 11. Cortical Connections from the Striate Cortex in the Rat.- Acknowledgments.- References.- 3 Multiple Representations of the Visual Field: Corticothalamic and Thalamic Organization in the Cat.- 1. Introduction.- 2. Retinotopic Organization in Lateral Posterior Complex.- 2.1. Projections of Area 17.- 2.2. Projections of Area 18.- 2.3. Projections of Area 19.- 2.4. Form of the Visual Field Representations.- 3. Lateral Posterior Complex Organization.- 3.1. Subdivisions Based on Connectional Patterns.- 3.2. Applications to Study of Cortical Interconnections.- 4. Interconnections of Cortex and Thalamus.- 4.1. Corticothalamic Connections.- 4.2. Thalamocortical Connections.- 5. Summary.- Acknowledgments.- References.- 4 Families of Related Cortical Areas in the Extrastriate Visual System: Summary of an Hypothesis.- 1. Multiple Ascending Channels in the Visual System.- 2. Experimental Questions and an Hypothesis about the Thalamocortical Connections.- 3. Identification of Extrageniculate Thalamic Subdivisions by Their Afferent Connections.- 4. Evidence for Systematic Groupings of Thalamic-Extrastriate Connections.- 5. Family Clusters in the Extrastriate Cortex.- Acknowledgments.- References.- 5 Cortical and Subcortical Connections of Visual Cortex in Primates.- 1. Introduction.- 2. The Principal Afferent Pathways to Cortex.- 2.1. The Geniculostriate System.- 2.2. The Tectopulvinar System.- 3. A Brief Outline of the Subdivisions of Visual Cortex in Primates.- 4. Projections of VI.- 5. Projections of VII.- 6. Projections of MT.- 7. Projections of Other Visual Areas in the OwlMonkey.- 8. Corpus Callosum Projections.- 9. Connections of Subdivisions of Visual Cortex with Subcortical Structures.- 9.1. Cortical Projections to the Lateral Geniculate Nucleus and Superior Colliculus.- 9.2. Projections to the Pulvinar Complex.- 9.3. Projections to the Pregeniculate Nucleus and the Reticular Nucleus of the Thalamus.- 9.4. Projections to the Basal Ganglia.- 9.5. Projections to the Pons.- 10. Reciprocal and Nonreciprocal Connections.- 11. Laminar Patterns of Connections.- 12. Conclusions.- Abbreviations.- References.- 6 Organization of Extrastriate Visual Areas in the Macaque Monkey.- 1. Introduction.- 2. Two-Dimensional Cortical Maps.- 3. Visual Areas of the Occipital Lobe.- 3.1. The Location of Area MT.- 3.2. Functional and Topographical Organization of MT.- 3.3. Interhemispheric Connections.- 4. Conclusion.- Acknowledgments.- References.- 7 Visual Topography and Function: Cortical Visual Areas in the Owl Monkey.- 1. Topographic Organization.- 2. Functional Correlates.- 3. Homologous Cortical Visual Areas in Other Species.- 4. Significance of Multiple Cortical Areas.- Acknowledgments.- References.- 8 Cortical Visual Areas of the Temporal Lobe: Three Areas in the Macaque.- 1. Introduction.- 2. The Middle Temporal Area (MT).- 2.1. Location and Architectonics.- 2.2. Neuronal Properties.- 2.3. Anatomical Connections.- 2.4. Behavioral Effects of Removal.- 3. Inferior Temporal Cortex (IT).- 3.1. Location and Architectonics.- 3.2. Neuronal Properties.- 3.3. Anatomical Connections.- 3.4. Behavioral Effects of Removal.- 4. Superior Temporal Polysensory Area (STP).- 4.1. Location and Architectonics.- 4.2. Neuronal Properties.- 4.3. Anatomical Connections.- 4.4. Behavioral Effects of Removal.- 5. An Hypothesis: Three Classes of Extrastriate Visual Areas.- Acknowledgments.- References.

Neurons in human epileptic cortex. Response to direct cortical stimulation.

Abstract: ✓ During craniotomy for surgical treatment of medically intractable epilepsy, single neurons were recorded from the lateral temporal cortex of 11 awake patients. A total of 83 neurons were recorded, and their response to repetitive direct cortical stimulation with ascending and descending frequency ramps between 1 to 10 Hz was evaluated. More normal units from the suspected epileptogenic cortex responded to repetitive stimulation at frequencies between 5 to 10 Hz with augmented action potential bursts than did units from cortex thought not to be primarily epileptogenic. This burst response might persist for up to 30 seconds after the frequency ramp had descended from 10 to 1 Hz. Except in two cases, this augmentation of burst response was not accompanied by afterdischarge on electroencephalography. These data would indicate that neurons within the region of suspected epileptogenic cortex demonstrate a greater propensity for afterdischarge to repetitive stimuli than do neurons in more normal cortex.

Properties of inferior temporal neurons in the macaque

Abstract: Publisher Summary This chapter discusses the properties of inferior temporal neurons in the macaque. Inferior temporal cortex is a high-level visual area critical for normal visual perception, learning and memory. In macaques, removal of inferotemporal cortex disrupts visual learning and visual recognition in the absence of any changes in basic visual functions such as acuity, perimetry, and various psychophysical thresholds. Discrimination learning and memory in other modalities remains normal. The response properties of inferior temporal units are heterogeneous and often complex. Most inferior temporal units respond better to three-dimensional objects than to spots, slits, or edges of any orientation. For a majority of these units, the response is a function of the texture, color, size, shape, or some other physical parameter of the object.

Kindling, transference phenomenon between temporal cortex and limbic structures in cats

Abstract: Publisher Summary This chapter discusses kindling, transference phenomenon between temporal cortex and limbic structures in cats. The transference phenomenon, which is the efficient rekindling of a secondary brain site after completing the primary site kindling, is the new method to study secondary epileptogenic changes. In an experiment described in the chapter, all animals developed generalized convulsions following daily stimulation. Depending upon the brain structure of the primary site, cortical kindling (anterior, mid, and posterior sylvian gyrus) and limbic kindling (amygdaloid, hippocampal, and septal) were divided. One of the characteristic findings of the cortical kindling was the instability of the final stage of convulsions, that is, frequent regression from generalized convulsion to partial seizure. Positive transfers from the sylvian gyrus kindling to the limbic structure in some animals, and emergence of interictal discharges in the amygdala and hippocampus during cortical kindling were observed. These changes had no influence on the principal pattern of sylvian gyrus seizure development. Together with negative transference from limbic kindling to the sylvian gyrus, neural changes involving in the seizure development may be different between the cortical kindling and the limbic kindling.

Effect of repeated convulsive seizures on brain GABA levels

Abstract: Repeated audiogenic seizures (4 times a day for 14 days), in genetically selected sensitive mice, induce a significant decrease in GABA level in the following brain areas: nucleus caudatus, posterior colliculus, occipital and frontal cortex, cerebellum, substantia nigra, hippocampus, amygdala, and temporal cortex. No variations were observed in olfactory bulbs, pons medulla, hypothalamus, thalamus, or cochlear area.

[Efferent and afferent connections of the nucleus lateralis posterior thalami ("pulvinar") in the albino rats (author's transl)]

Abstract: The efferent and afferent connections of the lateral posterior nucleus (LP) of the albino rat were investigated light microscopically with the silver-degeneration-methods and the HRP-methods as well. The results are: 1. The main projection region of the LP is the area of 18a of the peristriate visual cortex. Most degenerating axons terminate in layer IV. A few fibers pass layers III and II and terminate in layer I. It is not sure if there are also terminating fibers in layer IV. We could not find a topistic relation between LP and area 18 a. 2. We observed a small number of degenerating fibers in area 17, too. 3. A part of the degenerating fibers runs to the temporal cortex end enters area 20. 4. There is no evidence for a projection of the LP to both the subcortical regions and to the superior colliculus. 5. The majority of the LP's afferent fibers originates - on the subcortical level - from the superior colliculus. Especially the lamina III (Str. opticum) of the ipsilateral and of the contralateral side is here the source of fibers terminating in the LP. 6. Other subcortical sources of fibers terminating in the LP are: the pretectal region, the ventral part of the LGN, the Zona incerta, the thalamic reticular formation, and the dorsal raphe nucleus. 7. There exists a fiber projection of the area 17 to the LP. The axons originate mainly from pyramidal cells in layer V. It is discussed whether the area-17-fibers terminating in the LP are collaterals of the fibers terminating in the superior colliculus. The projection of the area 18a to the LP is of greater importance. The axons of this area originate mainly from cells of the layer VI. It becomes obvious that the thalamic relay-station of the second visual pathway seems to project nearly exclusively to the neocortex. In contrast to the dorsal LGN, however, the LP is not only a simple relay-station for visual information as also non-visual information arrives here. The morphological basis for these inputs has not yet been clarified completely. We have to take into consideration as well as the connections with the superior colliculus and the pretectal region and the cortical connections. It is remarkable that there exists also a projection of LP-fibers to a region outside the classical visual cortex. In mammals of higher evolution that kind of projection extends increasingly. It is discussed if - under comparative-anatomical aspect - the morphological changes in the pulvinar region are an expression of the neocorticalization, whereas the morphological changes in the dorsal LGN reflect mainly the functional specialization of the visual system.

The postnatal development of the lamina V pyramidal cells in the temporal cortex of the albino rat

Abstract: 1. The development of layer V pyramidal neurons is analysed quantitatively in albino rat temporal ("auditory") cortex from the 1st to the 90th postnatal days (12 stages). The length of apical dendrites, the number of primary dendrites and the total amount of apical dendrite spines are registered in Golgi-Cox preparations (55 animals). The diameters of the nucleus, length and width of the perikaryon and the relation between nucleus and perikaryon are measured in Nissl-series (45 animals). 2. Two types of development can be recognised by the examined parameters: --Length of apical dendrites, number of primary dendrites and of apical dendrite spines aspire more or less continuously to a maximum value. --Sizes of nucleus and perikaryon show intermediately a higher value than the terminal one ("overshooting growth"). 3. The postnatal development of the parameters suggests that the dendritic growth (also after initiated phase) starts from the perikaryon and relates with dendritic neuroplasmic flow. 4. In order to give general statements about the evolution of layer V pyramidal neuron's rates of growth are counted and their degree of maturity is determined. The biggest rates of growth are reached up to the 12th day post partum. At this time the pyramidal neurons have a relatively high degree of maturity. 5. There are two periods with especially marked alterations of structure of the layer V pyramidal neurons. These alterations are regarded as morphokineses according to Scharf. I. The morphological changes between the 8th and the 12th day are regarded as "morphokinesis as a reaction to planned crises" (2.2., according to Scharf 1970). In this case the critical situation is the beginning of hearing of the young rats, which is to be prepared. II. The morphological changes between the 24th and 36th day take place in the critical period of primary socialization (Scott et al. 1974). This could be understood as "morphokinesis as a reaction to environmental influences" (2.1., according to Scharf 1970). In this period it is possible, that the layer V pyramidal neurons of the temporal cortex of the rat play a role in learning and memory.

Backward masking in monkeys after foveal prestriate and inferior temporal cortex lesions

Abstract: In the monkey, foveal prestriate and inferior temporal cortex lesions produce a profound impairment of visual discrimination learning. In this experiment, we examined whether these impairments were associated with a loss of visual sensitivity under conditions of visual masking. Backward masking curves were obtained for two monkeys before and after temporal lobe lesions and for one normal human subject. When tested under the same conditions, human and animal curves were the same. The lesions had no effect on visual masking, although they did impair visual learning.

Changes in the cerebral cortex in temporal lobe epilepsy

Abstract: Biopsy specimens of the temporal cortex were taken from three patients suffering from temporal epilepsy of different origin. As a result of examining the specimens under optic and electron microscopes and subsequent morphometric processing of the data a picture of layer-by-layer changes in the cortex (field 21/38) was obtained. These changes consisted in appearance of the so-called dark cells, degenerating synaptic buds and myelin fibres, and increase of the percentage of astrocytes and proliferation of their processes. The data obtained suggest that in this disease there occurs a gradual destruction of neurocytes which leads to disturbances of the interneuronal relations.

Muscle tone and movement

Abstract: The frontal, postcentral, and temporal cortex play a part in the planning of voluntary movements. Subcortical structures also participate in the programming of movement, the basal ganglia for slow smooth movements and the cerebellum for fast movements. The outflow from the sensorimotor cortex comprises pyramidal fibers and parapyramidal fibers, the latter being distributed to basal ganglia, thalamus, cerebellum, and brainstem. The vestibulospinal and facilitatory reticulospinal tracts facilitate the motor neurons of antigravity muscles and the stretch reflex. The inhibitory reticulospinal tract, which opposes these actions, is driven from the motor cortex, thus forming an inhibitory cortico­reticulospinal pathway, the interruption of which increases muscle tone. The pyramidal tract, which arises from the sensorimotor cortex and continues into the spinal cord as crossed and uncrossed corticospinal tracts, provides the monosynaptic as well as polysynaptic control of motor neurons responsible for skilled movements. It facilitates extension and abduction movements in the upper limbs and the flexor synergy in the lower limbs of man. The pyramidal tract also regulates afferent inflow to the cortex from the posterior columns by the presynaptic inhibition of the cuneate and gracile nuclei. Pyramidal and extrapyramidal pathways are complementary in the control of movement.