Area Striata Research Articles

Atypical Gender Development: Why I Did Not Sign the GIRES-Review

ABSTRACT This article discusses the review on Atypical Gender Development, published by the Gender Identity Research and Education Society (GIRES) in the International Journal of Transgenderism 9(1), 2006, pp. 29–44. Although appreciating the initiative of GIRES, the author, who was invited to join the signatories of the review chose to not do so for five major reasons: (1) The phenomenology of transgenderism displays such a great variety that it can not be explained by any individual factor, be it constitution, morphology, hormones or psychology. (2) The role of the Bed nucleus of the area striata of the hypothalamus is overemphasized in the review. (3) Regrets after SRS challenge biological explanations of transsexualism. (4) Dwelling on biological explanations may, as the history of sexology shows, be used in favor as well as against subject. (5) Striving for legal and social acknowledgement of transgendered persons and improvement of treatment conditions does not need biology as an argument.

Blood flow increases in common carotid artery, lower lip and palate elicited by lingual nerve stimulation in anesthetized cats

The subcortical projection of the occipital lobe of the prosimian, Galago crassicaudatus, can be separated into four different systems: occipitopontine, occipitogeniculate, occipitothalamic and occipitotectal. The occipitopontine system contains fibers to the zona incerta (from the peristriate cortex) to the nucleus tractus opticus accessorius and to the ventrolateral part of the griseum pontis. The degeneration in the pons is more abundant after ablation of the lateral part of the striate area than after lesion in the medial part, also the ablation of the peristriate area reveals a strong connection. The occipitogeniculate system contains fibers to the nucleus peripeduncularis, the nucleus praegeniculatus and the lateral geniculate body (LGB). The degeneration in the LGB, when studied by Nauta's method, is mainly localized in the layers 5, 4 and 3. The projection of the peristriate area is to the middle third of the LGB, whereas the striate cortex projects to the medial third. The occipitothalamic system projects to the nucleus reticularis thalami, nucleus lateralis dorsalis intermedius and the pulvinar. The reticular nucleus receives fibers from the whole occipital lobe. The nucleus lateralis dorsalis intermedius also receives fibers from the whole occipital lobe except for the medial part of the area striata. The projection to the nucleus pulvinaris inferior is more significant than that to the nucleus pulvinaris dorsalis. Occipitopretectal fibers can be traced to the nucleus praetectalis and limitans. The occipitotectal fibers terminate in the lateral third of the tectum opticum.

A revised cytoarchitectonic map of the neocortex of the rabbit (oryctolagus cuniculus).

The cytoarchitectonic parcellation of the rabbit's neocortex has been investigated in 6 hemispheres which had been fixed by perfusion, embedded in paraffin and sectioned at either 9 μm or 20 μm in various planes. In addition to the classical method of microscopic observation, and automatic scanning procedure using an image analyser for measuring grey level indices was employed. By printing computer plots of various ranges of grey level indices, this method permits visualization of structural differences between various cytoarchitectonic fields. By evaluating the plots, cytoarchitectonic maps can be constructed which are based on objective data and therefore less influenced by subjective judgment than the maps obtained with the classical method. — In some regions the results based on the quantitative method are in agreement with the commonly used maps of Rose (1931), and in other regions widely at variance. It is shown, for instance, that the area striata as defined by Rose (1931) is composed of two distinct fields, viz. areas Oc 1 and 2, which are separated from each other in the rostro-caudal direction. These and other findings are described in detail, compared with the observations of Rose (1931), and related to the literature on functional localization in the rabbit's neocortex. Attention is drawn to the fact that the results obtained in 6 hemispheres leave no doubt that individual variations in size and shape of the entire hemisphere as well as of the various cytoarchitectonic fields do occur, and will have to be taken into account if cytoarchitectonic maps such as those published in the present paper are to be used in the context of experimental work.

Topography of retinal representation in the rabbit cortex: an experimental study using transneuronal and retrograde tracing techniques.

The cortical representation of the retina in rabbits was studied autoradiographically using transneuronal transport of tritiated proline and tritiated fucose. Injection of one eye produced cortical labelling on both sides. There was no indication of ocular dominance columns. On the contralateral side, the labelling was found in cortical layers II-IV, and partly also in layer VI of area striata and the caudal part of area peristriata, and in layer IV of most of area occipitalis. In addition, there was a patch of labelling in layers II-IV of the temporal cortex. On the ipsilateral side, the labelling was restricted to layer IV in a strip of cortex comprising area striata and area occipitalis along their common border. The cortical labelling in area striata and occipitalis was interpreted as evidence for a direct geniculo-cortical projection. This was confirmed by demonstration of retrogrately labelled nerve cells in the lateral geniculate nucleus produced by small injections of horseradish peroxidase into area occipitalis and area striata. In experiments with intraocular injections of tritiated adenosine, transneuronal cortical labelling was much weaker and more diffuse. In addition to the neuropil, nerve cell bodies and glial cells were also labelled.

On the pigmentation pattern of the human area striata

Pigment-architecturally, within the area striata of man, IVcbeta differs considerably from bright adjacent layers because of the presence of deeply staining lipofuscin granules.

Laminar Thermocoagulation of the Visual Cortex in the Rat; pp. 294–307

Hooded rats were trained on a series of four visual discrimination tasks in a Y-maze, and subjected to a variety of posterior cortical lesions. In 17 animals this consisted of an extensive aspiration lesion contralateral to a more superficial lesion made by laminar thermocoagulation and centered over the striate area. After operation the animals were tested on the same problem series. The behavioral deficit in this group varied with the extent and depth of the thermal lesion, and six animals with very superficial thermal lesions displayed an isolated difficulty in solving an encircled triangle problem. This deficit seemed to be referable to widespread involvement of supragranular cortex, and specifically of layer I of area striata which receives an input from the nonspecific thalamocortical afferents. The possible influence of various interlaminar projections upon underlying vertically-oriented cell columns as a mechanism for the mediation of ''selective attention'' was discussed.

Laminar thermocoagulation of the visual cortex in the rat. II. Visual pattern discrimination.

Hooded rats were trained on a series of four visual discrimination tasks in a Y-maze, and subjected to a variety of posterior cortical lesions. In 17 animals this consisted of an extensive aspiration lesion contralateral to a more superficial lesion made by laminar thermocoagulation and centered over the striate area. After operation the animals were tested on the same problem series. The behavioral deficit in this group varied with the extent and depth of the thermal lesion, and six animals with very superficial thermal lesions displayed an isolated difficulty in solving an encircled triangle problem. This deficit seemed to be referable to widespread involvement of supragranular cortex, and specifically of layer I of area striata which receives an input from the nonspecific thalamocortical afferents. The possible influence of various interlaminar projections upon underlying vertically-oriented cell columns as a mechanism for the mediation of 'selective attention' was discussed.

Laminar Thermocoagulation of the Visual Cortex in the Rat; pp. 308–321

Hooded rats were trained on a series of four visual discrimination tasks in a Y-maze, and subjected to a variety of posterior cortical lesions. In 17 animals this consisted of an extensive aspiration lesion contralateral to a more superficial lesion made by laminar thermocoagulation and centered over the striate area. After operation the animals were tested on the same problem series. The behavioral deficit in this group varied with the extent and depth of the thermal lesion, and six animals with very superficial thermal lesions displayed an isolated difficulty in solving an encircled triangle problem. This deficit seemed to be referable to widespread involvement of supragranular cortex, and specifically of layer I of area striata which receives an input from the nonspecific thalamocortical afferents. The possible influence of various interlaminar projections upon underlying vertically-oriented cell columns as a mechanism for the mediation of ''selective attention'' was discussed.

Chromatic information processing in the foveal projection ( Area striata) of unanesthetized primate

This investigation concerns the role of the foveal projection onto area striata in primates in the encoding of chromatic information as revealed by microelectrode recording in unanesthetized animals. The emphasis of the discussion is on the elaboration of a taxonomy of spectral response types found. In general, the experimental results obtained show two major sorts of responding: brightness and chromatic. One-half of the cells were “brightness cells” (those most sensitive to stimulus intensity and less concerned with wavelength). “Chromatic cells” (those showing responses that best correlate with wavelength and to a lesser extent with intensity) were of three major subcategories. “Pure hue” cells responding only to some narrow band of the spectrum. “Opponent color cells” responded by increasing their activity to part of the spectrum and decreasing activity for the rest of the spectrum when compared with resting levels in the dark. “Triphasic opponent color cells” were like opponent color cells except they responded by excitation, inhibition, excitation again (or the inverse pattern) in response to the spectrum. The complexity of chromatic response is believed to be related to the complexity of pattern responses, which was previously known to be related to anatomical location within the several layers of striate cortex.

Anterograde degeneration study of the cortical projections of the lateral geniculate and pulvinar nuclei in the tree shrew (Tupaia glis).

AbstractSixty lesions were placed in the pulvinar nucleus or the lateral geniculate nucleus of the tree shrew, and degenerated axons and their terminals were traced to the cortex. In all but two of the animals the electrode approached the thalamic target through the cerebellum and midbrain, thus sparing the cortex and thalamic nuclei other than the target nuclei. The results show that the pulvinar nucleus projects in a topographic fashion to an extensive cortical zone that includes areas 18, 19 and several temporal areas below 19. While there are several architectonic areas in its cortical target, no corresponding subdivisions could be established within the pulvinar nucleus, and its projections are best explained in terms of a single topographic organization. Further, since the pulvinar nucleus receives fibers from the superficial layers of the superior colliculus, its extensive cortical target can be regarded as primary visual cortex. The lateral geniculate nucleus projects in a precisely topographic fashion to area 17. Further, our evidence suggests that each layer of the lateral geniculate nucleus projects to a horizontal strip within the fourth or granular layer of area striata. With respect to the question of the relation between ocular dominance and location in area 17, the pattern of projections from the lateral geniculate nucleus does not reveal ocular dominance columns in layer IV of the tree shrew. In contrast to our results Hubel and Wiesel ('68, '69) have shown that in the monkey there are vertical columns of cells in layer IV driven by either the homolateral or the contralateral eye. The case for the cat (Hubel and Wiesel, '62, '65) may be different from either of the other two species, thus posing the problem of discovering the mammalian plan and departures from the prototypical organization.

A Sporadic Case of Cerebral Lipidosis in an Adult (Kufs)

SummaryThe authors reported a sporadic case of adult type of amaurotic idiocy.A female patient who had no specific hereditary taint had well worked as a primary schoolteacher until she married at the age of 27. About the same time she showed slight mental disturbance such as personality change and mild dementia. Subsequently her mental deterioration aggravated, so that she was obliged to retire from school 6 years after the onset of the disease. Then a gait disturbance and the following symptoms successively appeared: muscular rigidity, finger tremor, cerebellar symptoms, myoclonic jerks of the four limbs and generalized convulsions. EEG showed generalized spike and wave complex. The patient died of pneumonia at the age of 42 after the clinical course of 15 years.At autopsy, the brain weighed 900 g. and a moderate enlargement of the lateral ventricles was noted.Histologically the prominent feature was the swelling of the nerve cells of the cerebral cortex except for the area striata. In the regions other than the cerebral cortex, the distention of the neurons was found in the thalamus, oculomotor nucleus, substantia nigra, pontine nucleus, olivary nucleus, Purkinje cells, dentate nucleus and anterior horn cells of the spinal cord.Histochemical examination revealed the storage substance in the nerve cells consisted mainly of phospholipid with PAS‐positive glycolipid. Among the phospholipid sphingomyelin was dominantly exhibited.

The Relationship Between ERG and VER

From a comparison between local cone-ERG’s and VER’s, elicited with disc and ring stimuli, it appeared, that 1. the local cone ERG is highest in the macular region, because it is only dependent on the number of cones stimulated. 2. The VER, too, is mainly determined by the central retinal area. Apart from the high cone density in the macular region this is also due to the fact, that the contribution of the central cones is higher than that of the peripheral cones. This is caused partly through the convergence of the extrafoveal cones in the ganglion cells, partly through the localisation of the retinal projection in the area striata.

Dendritic spines in the visual cortex of the mouse: introduction to a mathematical model.

The spines of apical dendrites of the layer V pyramidal cells of the area striata in the mouse represent a sequence of post-synaptic structures receiving a variety of contacts from terminal fibers derived fundamentally from short axon cells and superficial pyramidal cells. The study of Golgi preparations of mice 180 days old shows the existence of the most complicated terminal structures over portions of apical dendrites at the levels of layers III and IV. Observations on young mice reveals the terminations of the specific afferent fibers on the dendrites of short axon cells. A mathematical model which defines the distribution of spines along the apical dendrites is introduced. The principal equation of the model has been adjusted from the data processing of microscope countings through a series of programs written for an IBM 7070. The equation defines satisfactorily the different distributions of dendritic spines in mice 10–180 days old raised in normal conditions and in complete darkness. The equation defines also the distribution of dendritic spines in the visual cortex of mice enucleated at birth on one side, and the distribution along the apical dendrites of various cortical areas of the hamster, cat and man. The number of dendritic spines increases with the age of the subject and their distribution varies significantly according to the values of the parameters of the model.

Post-primary flash-evoked responses in unanaesthetized night- and day-active monkeys.

1. In the night-active Galago crassicaudatus the extent of cortical areas striata (17) and prestriata (18), and the stereotaxic coordinates of the optic tract, lateral geniculate body and pulvinar were anatomically determined. Electric shocks applied to the lateral geniculate elicit area prestriata response patterns which differ from and are longer in latency than area striata responses. 2. In the dark-adapted Galago, light-flashes of progressive intensity or duration evoke in visual cortex a primary a wave, with 16–22 msec latency, and a subsequent post-primary b complex consisting of one or two positive waves within the latency range of 30–70 msec. In the day-active Saimiri sciureus, a different response is elicited, composed of 6–9 early low-voltage oscillations followed by late, higher voltage waves exceeding 70 msec in latency. 3. Simultaneously applied steady light produces in Galago an elective postprimary b complex potentiation, which contrasts with the reduction of the oscillations recorded from the optic tract and lateral geniculate body, and the reduction of the cortical primary a wave; in Saimiri, it induces only a slight potentiation of cortical oscillations in the latency range of 45–60 msec, and, as in Galago, a reduction of lateral geniculate oscillations. In both species the steady light effects of cortical potentiation are elicited also by applying steady light to the retina opposite to that stimulated by the testing flash, thus suggesting a central origin of these effects and a binocular cortical convergence. 4. In both species, flash-evoked responses in area striata (17) and area prestriata (18) undergo the same alterations during steady light. 5. Flash-evoked responses were recorded from the intergeniculate (inferior) nucleus of the pulvinar; during steady light they were depressed in Galago and totally suppressed in Saimiri. 6. Within the limits of the investigation modalities used, the present results on Galago did only slightly differ from previous ones on cat, but those in Saimiri proved to differ from both.

Descending subcortical projections from the occipital lobe of Galago crassicaudatus

The subcortical projection of the occipital lobe of the prosimian, Galago crassicaudatus, can be separated into four different systems: occipitopontine, occipitogeniculate, occipitothalamic and occipitotectal. The occipitopontine system contains fibers to the zona incerta (from the peristriate cortex) to the nucleus tractus opticus accessorius and to the ventrolateral part of the griseum pontis. The degeneration in the pons is more abundant after ablation of the lateral part of the striate area than after lesion in the medial part, also the ablation of the peristriate area reveals a strong connection. The occipitogeniculate system contains fibers to the nucleus peripeduncularis, the nucleus praegeniculatus and the lateral geniculate body (LGB). The degeneration in the LGB, when studied by Nauta's method, is mainly localized in the layers 5, 4 and 3. The projection of the peristriate area is to the middle third of the LGB, whereas the striate cortex projects to the medial third. The occipitothalamic system projects to the nucleus reticularis thalami, nucleus lateralis dorsalis intermedius and the pulvinar. The reticular nucleus receives fibers from the whole occipital lobe. The nucleus lateralis dorsalis intermedius also receives fibers from the whole occipital lobe except for the medial part of the area striata. The projection to the nucleus pulvinaris inferior is more significant than that to the nucleus pulvinaris dorsalis. Occipitopretectal fibers can be traced to the nucleus praetectalis and limitans. The occipitotectal fibers terminate in the lateral third of the tectum opticum.

Structural changes in the area striata of the mouse after enucleation.

The optic pathways of the mouse have been studied by tracing of degenerating fibers after enucleation and coagulation of the lateral geniculate nucleus. The effects of unilateral enucleation at birth in the contralateral area striata of the mouse have been studied with the Golgi method. The number of spines on three different portions of the apical dendrites of layer V pyramidal cells have been counted in the affected area striata of mice 24 and 48 days old enucleated at birth. The results were compared with the countings obtained in the area striata homolateral to the enucleated side and with controls of the same ages. The results indicated that enucleation produces, through a series of transneuronal changes, significant diminution of the number of spines in the apical dendritic segments located in layer IV. The diminution of dendritic spines is more pronounced in younger animals. Specific variations in the orientation of dendrites of stellate cells with ascending axons have been observed in enucleated animals. The significance of these findings has been discussed suggesting the existence of compensatory mechanisms which affect significantly the intrinsic organization of the area striata.

Marsupial interhemispheric relation.

AbstractThree different responses recorded from the opossum neocortex following a stimulus to the homotopical point on the contralateral hemisphere were: the interhemispheric early response (IER), the interhemispheric delayed response (IDR), and the rhythmic afterdischarge (RA). The IER was a short latency biphasic slow wave evoked potential which could be recorded from every homotopic point on the neopallium with the exception of a part of the striate cortex. Each active homotopic point had a limited heterotopic halo. The homotopic positive peak latency varied from 5.3 msec in the area parietalis to 14.7 msec in the area striata. Interhemispheric transfer was effected via the anterior commissure. The IDR was a late slow wave evoked potential and had an extensive heterotopic representation. This potential could be recorded in the contralateral hemisphere after sectioning the anterior commissure. The homotopic positive peak latency varied from 60.2 msec in the area parietalis to 76.1 msec in area striata. To abolish the IDR both the di‐mesencephalic junction and the interthalamic commissure had to be sectioned. The RA is a very labile late oscillatory potential which was very difficult to demonstrate without a computer of average transients. The pattern of its homotopic and heterotopic representation resembled very closely that of the IER. Under the conditions of our experiment it had a negative peak latency of 224–230 msec, a frequency of oscillation of three seconds and a maximum duration of 2.2 seconds. To abolish the RA both the di‐mesencephalic junction and the interthalamic commissure had to be sectioned. The dorsal commissure contained no neopallial intorhemispheric fibers. The anterior commissure carried these commissural connections. The two late responses reported in the opossum fell within the general context of mammalian late responses.

Apical dendritic spines of the visual cortex and light deprivation in the mouse.

The effects of light deprivation on the number of apical dendritic spines have been studied in the visual cortex of the mouse. In the portion of the apical dendrites of layer V-pyramidal cells traversing layer IV, dendritic segments of 50 μ in length from different cells were selected. The number of spines on each of 50 different segments per animal was counted. The countings were done in the areae striata and temporalis prima from mice raised in complete darkness since birth up to 22–25 days old. The observations were compared with the countings obtained in the areae striata and temporalis prima from mice raised under normal conditions. The results indicated that mice raised in darkness had a significant reduction in the number of spines per dendritic segment at the level of layer IV in area striata when compared with control animals. No significant difference was found in the number of spines per dendritic segment in layer IV between both groups of normal and dark raised mice in the area temporalis prima. The mean number of dendritic spines per consecutive segments along complete apical dendrites of layer V-pyramidal cells in area striata has been found to increase exponentially with the distance from the cell body. The same exponential relation, but with somewhat lower values, was obtained in the apical dendrites in area striata in mice raised in darkness. The significance of these findings were discussed. It was concluded that: First, visual sensory deprivation affect the fine structure of the central nervous system. Second, the results observed support the assumption that structural changes in the nerve cells occur as the result of experience.

Optic projections to nonvisual cortex of the cat.

Optic projections to nonvisual cortex of the cat.K E Bignall, M Imbert, and P BuserK E Bignall, M Imbert, and P BuserPublished Online:01 May 1966https://doi.org/10.1152/jn.1966.29.3.396MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByConnections of the insular cortex in kittens: An anatomical demonstration with wheatgerm agglutinin conjugated to horseradish peroxidase techniqueInternational Journal of Developmental Neuroscience, Vol. 9, No. 5Visual localization and discrimination after ibotenic lesion of the cat orbito-insular cortexBehavioural Brain Research, Vol. 22, No. 1Physiological properties of visually responsive neurones in the insular cortex of the catNeuroscience Letters, Vol. 64, No. 3Cortical visual input to the orbito-insular cortex in the catBrain Research, Vol. 221, No. 1A search for olfactory receiving areas in the cerebral cortex of catsNeuroscience, Vol. 6, No. 1Auditory cortex lesions and auditory-visual associative learning in catsBrain Research, Vol. 176, No. 2Efferent projections of the insular and temporal neocortex of the catBrain Research, Vol. 117, No. 2Thalamic projections to visually responsive regions of parietal cortexBrain Research Bulletin, Vol. 1, No. 5Afferents to the lateral suprasylvian gyrus of the cat traced with horseradish peroxidaseBrain Research, Vol. 78, No. 1Visually triggered oculomotor discharges with and without eye movementsBrain Research, Vol. 71, No. 2-3Chromatic information processing in the foveal projection (Area striata) of unanesthetized primateVision Research, Vol. 14, No. 2Phasic electrical activity in the brain associated with eye movement in waking catsBrain Research, Vol. 56Photically evoked potentials from cat neocortex before and after recovery from visual deprivationExperimental Neurology, Vol. 39, No. 1Corticocortical fiber connections of the cat cerebrum. III. The occipital regionBrain Research, Vol. 51Effects of subcortical ablations on cortical association responses in the catPhysiology & Behavior, Vol. 10, No. 2Origin of the early component of the evoked response in the association cortex of the catElectroencephalography and Clinical Neurophysiology, Vol. 32, No. 2Visual cortex efference to nonprimary cortex in the catBrain Research, Vol. 28, No. 3Unit study of exteroceptive inputs to claustrocortex in awake, sitting, squirrel monkeyBrain Research, Vol. 28, No. 1Diffuse light input and quality of reward determine the occurrence of ‘Reward Contingent Positive Variation’ (RCPV) in catBrain Research, Vol. 28, No. 1Visual evoked potentials in cortical auditory and anterior ectosylvian areas of catVision Research, Vol. 11On the origin of cortical association responses to visual stimulation in the catBrain Research, Vol. 14, No. 2Die wirkung von psychopharmaka auf visuell evozierte potentiale der katzeVision Research, Vol. 9, No. 4Localization and characteristics of the cortical waves associated with eye movement in the catExperimental Neurology, Vol. 22, No. 4Integrative activity of the thalamic pulvinar-lateralis posterior complex and interrelations with the neocortexExperimental Neurology, Vol. 22, No. 3Interaction between the primary sensory and association areas of the cerebral cortex in the catPhysiology & Behavior, Vol. 3, No. 5The ipsilateral cortical connexions of the somatic sensory areas in the catBrain Research, Vol. 9, No. 1Relearning a dark-light discrimination by cats after cortical and collicular lesionsExperimental Neurology, Vol. 20, No. 3Response of cells to restricted visual stimuli in an association area of cat cerebral cortexExperimental Neurology, Vol. 20, No. 1Photosensitive epilepsy: Relationships between the visual evoked responses and the epileptiform discharges induced by intermittent photic stimulationElectroencephalography and Clinical Neurophysiology, Vol. 23, No. 4Effects of diphenylhydantoin on spontaneous and evoked activity in the cat under chloralose anesthesiaElectroencephalography and Clinical Neurophysiology, Vol. 23, No. 4Photic evoked potentials in the cat: Evidence for a direct geniculate input to visual IIExperimental Neurology, Vol. 19, No. 2Auditory, somatic and visual input to association and motor cortex of the squirrel monkeyExperimental Neurology, Vol. 18, No. 3Interaction of cortical and peripheral inputs to polysensory areas of the cat neocortexExperimental Neurology, Vol. 18, No. 2Comparison of optic afferents to primary visual and polysensory areas of cat neocortexExperimental Neurology, Vol. 17, No. 3 More from this issue > Volume 29Issue 3May 1966Pages 396-409 https://doi.org/10.1152/jn.1966.29.3.396PubMed5961157History Published online 1 May 1966 Published in print 1 May 1966 Metrics

The neocortex and visual placing in rats

Hooded rats were tested for visual and tactual placing responses prior to and 3 weeks after partial or total neocortical ablation. An operational scaling technique was used to evaluate placing responses in terms of latency and extent of response. Removal of the anterior neocortex was followed by transient retardation of visual placing and by loss of tactual placing. Removal of the posterior neocortex resulted in loss followed by eventual recovery of visual placing but had no effect on tactual placing, and recovery could not be attributed to sparing of some portion of the area striata. Removal of all neocortex, except for small portions adjacent to the rhinal sulcus, resulted in loss of both tactual and visual placing responses, but visual orientation responses persisted. Further experimentation indicated that recovery of visual placing was possible after nearly complete ablation of the neocortex if extensive practice trials were given or if the lesion was performed in two separate stages with practice interpolated between stages. A tendency to recover accompanied repeated administrations of amphetamine, but this was not reliable. Recovery, when observed, appeared to be a function of practice because performance increased incrementally over 20 days of testing rather than occurring spontaneously. It was concluded that although both anterior and posterior neocortex are normally involved in, and certainly enhance, visual placing behavior in rats, neither seems necessary for such behavior to occur.