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L G Ungerleider

Publications and source records attributed to L G Ungerleider.

At least 19 recordsLinked to original sources
PubMed1991

Visual topography of area TEO in the macaque.

Previous studies have mapped the visuotopic organization of visual areas from V1 through V4 in the occipital cortex and of area TE in the temporal cortex, but the cortex in between, at the occipito-temporal junction, has remained relatively unexplored. To determine the visuotopic organization of this region, receptive fields were mapped at 1,200 visually responsive sites on 370 penetrations in the ventral occipital and temporal cortex of five macaques. We identified a new visual area, roughly corresponding to cytoarchitectonic area TEO, located between the ventral portion of V4 and area TE. Receptive fields in TEO are intermediate in size between those in V4 and TE and have a coarse visuotopic organization. Collectively, receptive fields in TEO appear to cover nearly the entire contralateral visual field. The foveal and parafoveal representation of TEO is located laterally on the convexity of the inferior temporal gyrus, and the peripheral field is represented medially on the ventral surface of the hemisphere, within and medial to the occipitotemporal sulcus. Beyond the medial border of TEO, within cyteoarchitectonic area TF, is another visually responsive region, which we have termed VTF; this region may also have some crude visual topography. Bands of constant eccentricity in TEO appear to be continuous with those in V2, V3v, and V4. The upper field representation in TEO is located adjacent to that in ventral V4, with a representation of the horizontal meridian forming the boundary between the two areas. The lower field representation in TEO is located just anterior to the upper field but is smaller. In contrast to the orderly representation of eccentricity in TEO, we found little consistent representation of polar angle, other than the separation of upper and lower fields. The results of injecting anatomical tracers in two animals suggest that TEO is an important link in the pathway that relays visual information from V1 to the inferior temporal cortex. TEO is thus likely to play an important role in pattern perception.

Animals↗
PubMed1991

Dissociation of object and spatial visual processing pathways in human extrastriate cortex.

The existence and neuroanatomical locations of separate extrastriate visual pathways for object recognition and spatial localization were investigated in healthy young men. Regional cerebral blood flow was measured by positron emission tomography and bolus injections of H2(15)O, while subjects performed face matching, dot-location matching, or sensorimotor control tasks. Both visual matching tasks activated lateral occipital cortex. Face discrimination alone activated a region of occipitotemporal cortex that was anterior and inferior to the occipital area activated by both tasks. The spatial location task alone activated a region of lateral superior parietal cortex. Perisylvian and anterior temporal cortices were not activated by either task. These results demonstrate the existence of three functionally dissociable regions of human visual extrastriate cortex. The ventral and dorsal locations of the regions specialized for object recognition and spatial localization, respectively, suggest some homology between human and nonhuman primate extrastriate cortex, with displacement in human brain, possibly related to the evolution of phylogenetically newer cortical areas.

Adult↗
PubMed1991

Mapping the functional neuroanatomy of the intact human brain with brain work imaging.

The recent development of noninvasive methods for measuring local rates of energy metabolism or blood flow in the brain has made it possible to investigate functional neuroanatomy in healthy human subjects. The best of these methods, high resolution measurement of regional cerebral blood flow (rCBF) with positron emission tomography (PET), provides a precision of anatomical localization that far exceeds that attainable with human brain lesion studies. Moreover, the study of healthy subjects avoids possible confounding effects of brain lesions, such as compensatory reorganization of brain function. PET-rCBF studies have already identified several cortical areas involved in higher-order visual processing, indicating that functional neuroimaging may yield a map of human visual cortex analogous to maps that have been developed by vision research in nonhuman primates. PET-rCBF studies of imagery and language demonstrate the potential of functional neuroimaging to map regions of human cortex that perform functions that cannot be studied so easily in nonhuman primates or perform functions that humans do not share with other species.

Attention↗
PubMed1991

Lesions of inferior temporal area TE in infant monkeys alter cortico-amygdalar projections.

When inferior temporal area TE is removed bilaterally in infant monkeys, the normally transient projection from area TEO to the lateral basal nucleus of the amygdala is maintained, and the normally limited projection from area TEO to the dorsal part of the lateral nucleus of the amygdala expands to invade the terminal space in the lateral nucleus that is normally occupied by terminals from area TE. The maintenance and sprouting of these projections from area TEO could play a role in the permanent preservation of visual memory ability in monkeys that have received bilateral removal of area TE in infancy.

Aging↗
PubMed1991

Organization of visual inputs to the inferior temporal and posterior parietal cortex in macaques.

It has been proposed that visual information in the extrastriate cortex is conveyed along 2 major processing pathways, a "dorsal" pathway directed to the posterior parietal cortex, underlying spatial vision, and a "ventral" pathway directed to the inferior temporal cortex, underlying object vision. To determine the relative distributions of cells projecting to the 2 pathways, we injected the posterior parietal and inferior temporal cortex with different fluorescent tracers in 5 rhesus monkeys. The parietal injections included the ventral intraparietal (VIP) and lateral intraparietal (LIP) areas, and the temporal injections included the lateral portions of cytoarchitectonic areas TE and TEO. There was a remarkable segregation of cells projecting to the 2 systems. Inputs to the parietal cortex tended to arise either from areas that have been implicated in spatial or motion analysis or from peripheral field representations in the prestriate cortex. By contrast, inputs to the temporal cortex tended to arise from areas that have been implicated in form and color analysis or from central field representations. Cells projecting to the parietal cortex were found in visual area 2 (V2), but only in the far peripheral representations of both the upper and lower visual field. Likewise, labeled cells found in visual areas 3 (V3) and 4 (V4) were densest in their peripheral representations. Heavy accumulations of labeled cells were found in the dorsal parieto-occipital cortex, including the parieto-occipital (PO) area, part A of V3 (V3A), and the dorsal prelunate area (DP). In the superior temporal sulcus, cells were found within several motion-sensitive areas, including the middle temporal area (MT), the medial superior temporal area (MST), the fundus of the superior temporal area (FST), and the superior temporal polysensory area (STP), as well as within anterior portions of the sulcus whose organization is as yet poorly defined. Cells projecting to areas TE and TEO in the temporal cortex were located within cytoarchitectonic area TG at the temporal pole and cytoarchitectonic areas TF and TH on the parahippocampal gyrus, as well as in noninjected portions of area TE buried within the superior temporal sulcus. In the prestriate cortex, labeled cells were found in V2, V3, and V4, but, in contrast to the loci labeled after parietal injections, those labeled after temporal injections were concentrated in the foveal or central field representations. Although few double-labeled cells were seen, 2 regions containing intermingled parietal- and temporal-projection cells were area V4 and the cortex at the bottom of the anterior superior temporal sulcus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Connections of inferior temporal areas TE and TEO with medial temporal-lobe structures in infant and adult monkeys.

As part of a long-term study designed to examine the ontogeny of visual memory in monkeys and its underlying neural circuitry, we have examined the connections between inferior temporal cortex and medial temporal-lobe structures in infant and adult monkeys. Inferior temporal cortical areas TEO and TE were injected with WGA conjugated to HRP and tritiated amino acids, respectively, or vice versa, in 1-week-old and 3-4-yr-old Macaca mulatta, and the distributions of labeled cells and terminals were examined in both limbic structures and temporal-lobe cortical areas. In adult monkeys, inferior temporal-limbic connections included projections from area TEO to the dorsal portion of the lateral nucleus of the amygdala and from area TE to the lateral and lateral basal nuclei; inputs to both areas TEO and TE included those from the lateral, lateral basal, and medial basal nuclei of the amygdala and to area TE from the accessory basal nucleus. Additional limbic inputs to both areas TEO and TE arose from the posterior portion of the presubiculum. In infant monkeys, we found, in addition to these adultlike connections, a projection from area TEO to the lateral basal nucleus of the amygdala. Inferior temporal cortical connections in adult monkeys included projections from area TEO to area TE and, in turn, from area TE to area TG and perirhinal area 36, as well as from area TE back to area TEO; inputs to both areas TEO and TE included those from area TG, perirhinal areas 35 and 36, and parahippocampal areas TF and TH. All of these adultlike connections were also observed in infant monkeys, but, in addition, the infants showed projections from area TE to perirhinal area 35 as well as to parahippocampal areas TF and TH, and from area TEO to area TF. Moreover, in infants, the projection from area TE to perirhinal area 36 was considerably more widespread than in adults, both in areal extent and in laminar distribution. The results therefore indicate the existence of projections in infant monkeys from inferior temporal areas to the amygdala, perirhinal cortex, and parahippocampal cortex that are either totally eliminated in adults or more refined in their distribution. Both elimination and refinement of projections thus appear to characterize the maturation of axonal pathways between the inferior temporal cortex and medial temporal-lobe structures in monkeys.

Aging↗
PubMed1990

Organization of visual cortical inputs to the striatum and subsequent outputs to the pallido-nigral complex in the monkey.

To determine the organization of visual inputs and outputs of the striatum, we placed multiple retrograde and anterograde tracers into physiologically identified portions of the striatum known to receive inputs from visual cortex in seven macaques. The injection sites included the tail and genu of the caudate nucleus (14 cases), the head of the caudate (1 case), and the ventral putamen (3 cases). Retrogradely labeled cells were located predominantly in layer 5 of the ipsilateral cortex but were also found in layers 3 and 6. After caudate injections, labeled cells were found both in large, nearly continuous regions of cortex topographically related to the site of the injection, and in several smaller cortical regions that were discontinuous and common to many or all of the injection sites. The continuously labeled regions included nearly all known visual cortical areas, except for the striate cortex. After injections in the rostral tail, the continuously labeled region included the rostral portion of Bonin and Bailey's (Urbana: University of Illinois Press. '47) area TE and adjacent portions of TF, TH, TG, and, occasionally, area 35 (Brodmann, Leipzig: J.A. Barth. '09). After injections into the posterior tail and ventral genu, the labeled region shifted posteriorly in TE and TF, and into TEO and the ventral parts of prestriate areas V4, V3, and (sparsely) V2. As the injection site was advanced into the dorsal genu, the labeled region shifted dorsally toward the parietal lobe, including prestriate areas MT and PO, parietal area PG (Brodmann's area 7), the ventral and lateral intraparietal sulcal areas (VIP and LIP, respectively), and area PE and adjacent area LC (Brodmann's areas 5 and 23, respectively). The discontinuous areas labeled by many different injections included the principal sulcus/frontal eye field region, the anterior cingulate cortex, and the superior temporal polysensory area. Thus, whereas temporal, occipital, and parietal visual cortical areas project into the caudate largely according to proximity, certain multimodal cortical areas seem to have a much wider projection. To determine whether visual cortical areas have additional projections to the caudate beyond the territory of our retrograde injection sites in the tail and genu. 3H-labeled amino acids were injected into areas TE, V4, and MT in three additional monkeys. The topographic location of label in the tail and genu of the caudate in these cases was consistent with the results from injections of retrograde tracers into the caudate.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1990

Pathways for motion analysis: cortical connections of the medial superior temporal and fundus of the superior temporal visual areas in the macaque.

To identify the cortical connections of the medial superior temporal (MST) and fundus of the superior temporal (FST) visual areas in the extrastriate cortex of the macaque, we injected multiple tracers, both anterograde and retrograde, in each of seven macaques under physiological control. We found that, in addition to connections with each other, both MST and FST have widespread connections with visual and polysensory areas in posterior prestriate, parietal, temporal, and frontal cortex. In prestriate cortex, both areas have connections with area V3A. MST alone has connections with the far peripheral field representations of V1 and V2, the parieto-occipital (PO) visual area, and the dorsal prelunate area (DP), whereas FST alone has connections with area V4 and the dorsal portion of area V3. Within the caudal superior temporal sulcus, both areas have extensive connections with the middle temporal area (MT), MST alone has connections with area PP, and FST alone has connections with area V4t. In the rostral superior temporal sulcus, both areas have extensive connections with the superior temporal polysensory area (STP) in the upper bank of the sulcus and with area IPa in the sulcal floor. FST also has connections with the cortex in the lower bank of the sulcus, involving area TEa. In the parietal cortex, both the central field representation of MST and FST have connections with the ventral intraparietal (VIP) and lateral intraparietal (LIP) areas, whereas MST alone has connections with the inferior parietal gyrus. In the temporal cortex, the central field representation of MST as well as FST has connections with visual area TEO and cytoarchitectonic area TF. In the frontal cortex, both MST and FST have connections with the frontal eye field. On the basis of the laminar pattern of anterograde and retrograde label, it was possible to classify connections as forward, backward, or intermediate and thereby place visual areas into a cortical hierarchy. In general, MST and FST receive forward inputs from prestriate visual areas, have intermediate connections with parietal areas, and project forward to the frontal eye field and areas in the rostral superior temporal sulcus. Because of the strong inputs to MST and FST from area MT, an area known to play a role in the analysis of visual motion, and because MST and FST themselves have high proportions of directionally selective cells, they appear to be important stations in a cortical motion processing system.

Animals↗
PubMed1989

Type I protein kinase C isozyme in the visual-information-processing pathway of monkey brain.

Previously using PKC isozyme-specific antibodies for immunoblot analysis, we demonstrated the heterogeneous distribution of PKC isozymes in various regions of monkey and rat brains and that type I PKC was most abundant in cerebellum, hippocampus, amygdala, and cerebral cortex (Huang et al.: J Biol Chem 262:15714-15720, 1987). Using these antibodies, we have also demonstrated that type I, II, and III PKC are products of PKC genes gamma, beta, and alpha, respectively (Huang et al.: Biochem Biophys Res Commun 149:946-952, 1987). By immunocytochemical analysis, type I PKC-specific antibody showed strong reactivity in various types of neuron in hippocampal formation, amygdala, cerebellum, and neocortex. In hippocampal formation, granule cells of dentate gyrus and pyramidal cells of hippocampus were heavily stained. By immunoblot analysis, relative levels of PKC isozymes in several areas of monkey cerebral cortex involved in the visual information processing and storage were determined. Both type II and III PKCs appeared to be evenly distributed and at moderate levels, type I PKC formed a gradient of increasing concentration rostral along the cerebral cortex of occipital to temporal and then to the limbic areas. Neurobehavioral studies have demonstrated that the neocortical and limbic areas of the anterior and medial temporal regions participate more directly than the striate, prestriate, and posterior temporal regions in the storage of visual representations and that both hippocampus and amygdala are important in the memory formation. As type I PKC is present at high levels in hippocampus, amygdala, and anterior temporal lobe, we predict that the type I protein kinase C may participate in the plastic changes important for mnemonic function.

Animals↗
PubMed1989

Projections from inferior temporal cortex to prefrontal cortex via the uncinate fascicle in rhesus monkeys.

In five rhesus monkeys (Macaca mulatta) we used anterograde and retrograde tracing techniques to investigate the projection from the inferior temporal cortex (area TE) to the prefrontal cortex as well as the course of the projecting fibers. The results showed that TE projects to both the inferior convexity and orbital surface of prefrontal cortex and that these projections course almost exclusively via the uncinate fascicle. Transection of the uncinate fascicle deprives the prefrontal cortex of virtually all input from TE, but leaves intact inputs from prestriate and parietal visual areas as well as the amygdala. Such transection also leaves intact many projections from TE to targets other than the prefrontal cortex, including the amygdala, ventral putamen, tail of the caudate nucleus, and pulvinar.

Amino Acids↗
PubMed1988

Fiber pathways of cortical areas mediating smooth pursuit eye movements in monkeys.

Recent studies in rhesus monkeys and human patients have increased our understanding of the role of various cortical regions in the generation of smooth pursuit eye movements. Little is known, though, about the cerebral white matter pathways mediating smooth pursuit. In this paper, we describe both the corticocortical and corticosubcortical projections from areas in the monkey brain known to be involved in smooth pursuit. The corticocortical pathways within one hemisphere consist of a sequence of arcuate fiber bundles interconnecting (1) striate cortex with an area in occipitoparietal cortex called the middle temporal (MT) area, (2) area MT with two areas in parietal cortex called the medial superior temporal (MST) and posterior parietal (PP) areas, and (3) area MST with area PP. An interhemispheric pathway interconnecting areas MT and MST consists of fibers sequentially passing through the tapetum, major forceps, and the splenium of the corpus callosum. The corticosubcortical pathway from area MST to the pontine nuclei and accessory optic system consists of fibers sequentially running through the internal sagittal stratum, the retrolenticular part of the internal sagittal stratum, and the cerebral peduncle. Based on the effects of lesions on pursuit eye movements, these corticocortical and corticosubcortical projections can be divided into sensory, motor, and attentional/spatial systems. Evidence from clinical studies suggests that homologous systems exist in the human cerebrum.

Animals↗
PubMed1987

The role of striate cortex in the guidance of eye movements in the monkey.

We studied the effect of unilateral striate cortical ablations on smooth pursuit and saccadic eye movements in the monkey. The monkeys made quite accurate saccades to stationary stimuli in the field contralateral to the lesion, and they readily pursued foveal targets moving in all directions. However, when visual stimuli were stepped into the field contralateral to the lesion and then began to move, thus insuring that the moving stimulus was confined to the impaired visual hemifield, several oculomotor abnormalities emerged. Saccades to moving stimuli presented in the impaired field consistently undershot targets that moved away from the central fixation point after the step, and overshot targets that moved back towards the central fixation point. There was little or no smooth pursuit eye velocity generated in any direction to moving stimuli in the impaired field, and the monkeys could not generate smooth pursuit to stimuli maintained a few degrees from the fovea in the impaired field, although they were able to pursue such stimuli held in the normal field. Ablation of striate cortex also affected the latencies of saccades. When step-ramp stimuli were presented in the normal field, the monkeys delayed the initiation of saccades to targets moving towards the central fixation point, and hastened the initiation of saccades to targets moving away from the central fixation point. By contrast, changes in the direction of target movement did not affect the latencies of saccades into the impaired field. The deficits seemed permanent, lasting as long as the monkeys were tested--over 2 years in one case--but they were not total. Each monkey could use stimuli moving into the affected field to develop some eye velocity, although this residual ability had a much longer latency and lower gain than that provided by the intact visual system. These results show that striate cortex is intimately involved in the estimation of stimulus velocity critical to the genesis of smooth pursuit and saccadic eye movements.

Animals↗
PubMed1986

Projections to the superior temporal sulcus from the central and peripheral field representations of V1 and V2.

In a series of three studies, we have begun to explore the sequence of visual information processing along the pathway from striate cortex (V1), through MT, into the parietal lobe. In this first study, we sought to establish the relationships among MT, the heavily myelinated zone of the superior temporal sulcus (STS), and the V1 and V2 projection fields in the STS. Autoradiographic material from seven hemispheres of six macaques injected with tritiated amino acids into either V1 or V2 was analyzed in detail, and the results were plotted onto two-dimensional reconstructions of the STS. Autoradiographic material from eight additional macaques with V2 injections was also examined. The results indicate that the central visual field representations of both V1 and V2 project into the heavily myelinated zone in the lower bank and floor of the STS, confirming prior studies, whereas the far peripheral representations of both V1 and V2 project into the cortex medial to this zone on the upper bank of the sulcus. There is no evidence that this medial cortex is a separate area that receives projections from V1 and V2 in parallel with the projections these areas send to the heavily myelinated zone. Rather, there seems to be a single projection field of V1 and V2 whose central representation lies within the heavily myelinated zone and whose most peripheral representation lies medial to it. Because of the difference in myelination between the central and peripheral field representations as well as visuotopic anomalies between them, we retain the term "MT" for the heavily myelinated zone and apply the term "MTp" to the far peripheral projection zone. Both MT and MTp are required to process the complete outputs of V1 and V2 within the STS and thus should probably be regarded as two distinctive parts of a single visual area. The difference in myelination between MT and MTp suggests that there is a difference in visual processing between the central and peripheral visual fields. The average size of MT is estimated to be 62 mm2, and the average size of MT and MTp combined to be 76 mm2, which is consistent with estimates derived from several other studies.

Amino Acids↗
PubMed1986

Multiple visual areas in the caudal superior temporal sulcus of the macaque.

Anatomical and physiological evidence indicates that, in addition to area MT, much of the cortex in the caudal superior temporal sulcus (STS) of the macaque has visual functions. Yet the organization of areas outside of MT remains unclear, and there are even conflicting data on the boundaries of MT itself. To examine these issues, we recorded form neurons throughout this region in three monkeys. Anterograde or retrograde tracers were injected into MT at the conclusion of recording to identify its projection fields. Based on differences in their visuotopic organization, neuronal properties, receptive field size, myeloarchitecture, and pattern of connections with MT, several visual areas were distinguished within the caudal STS. Area MT, defined as the heavily myelinated portion of the striate (VI) projection zone in STS, contained a systematic representation of only about the central 30 degrees--40 degrees of the contralateral field. The far peripheral field was represented medial to MT in MTp, which we had previously found receives projections from far peripheral V1 and V2 (Ungerleider and Desimone: J. Comp. Neurol. 248:147-163, 1986). Like MT, MTp contained a high proportion of directionally selective cells, and receptive field size in MTp was the size expected of MT fields if the latter were to extend into the periphery. Areas MST (medial superior temporal) and PP (posterior parietal) were found medial to MT and MTp. Both MST and PP had a high proportion of directionally selective cells, but only MST received a direct projection from MT. Cells in MST had larger receptive fields than those in either MT or MTp but nonetheless displayed a crude visuotopic organization. Receptive fields of cells in PP were even larger, some including the entire contralateral visual field. Furthermore, unlike cells in MST, some in PP responded to auditory or somesthetic stimuli in addition to visual stimuli. Area FST, which has a distinctive myeloarchitecture, was found anterior to MT in the fundus of the STS, for which it is named. FST received a direct projection from MT, but only about a third of its cells were directionally selective. Receptive fields of cells in FST were large, often included the center of gaze, and often crossed into the ipsilateral visual field. Area V4t (transitional V4) and a portion of V4 were found lateral to MT within the STS, and both received direct projections from MT. V4t has a distinctive, light myelination. Both areas had a low incidence of directionally selective cells, and both contained coarse representations of the lower visual field.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Cortical connections of visual area MT in the macaque.

We have identified the cortical connections of area MT and determined their topographic organization and relationship to myeloarchitectural fields. Efferents of MT were examined in seven macaques that had received injections of tritiated amino acids, and afferents were examined in one macaque that had received injections of two fluorescent dyes. The injection sites formed an orderly sequence from the representation of central to that of peripheral vision in the upper and lower visual fields. In addition to connections with the striate cortex (V1), connections were found between MT and a variety of extrastriate areas, including V2, V3, V3A, V4, V4t, VIP, MST, FST, possibly PO, and, finally, the frontal eye field. The connections of MT with V1, V2, and the dorsal and ventral portions of V3 were topographically organized and consistent with the visuotopic arrangement reported previously in these areas. V2 could be distinguished from V3 by the distinctive myeloarchitectural appearance of the former. Connections with areas V4 and V4t also displayed at least a coarse visuotopic organization, in that the central representation of MT projected laterally in these areas and the peripheral representation projected medially. The lower visual field representation of V4 was located dorsally, on the prelunate convexity, while the upper field representation was located primarily on the ventral aspect of the hemisphere. V4t had a distinctively light myeloarchitecture and received projections from only the lower field representation of MT. The remaining connections of MT were with areas located entirely in the dorsal half of the hemisphere. There were widespread connections with areas MST and FST in the superior temporal sulcus, with some evidence for a crude visuotopic organization in MST. Connections were also found with area VIP in the intraparietal sulcus, with area V3A on the annectent gyrus, possibly with area PO in the dorsomedial prestriate cortex, and, finally, with the frontal eye field on the anterior bank of the lower limb of the arcuate sulcus. Area FST and parts of both MST and VIP had a distinctive myeloarchitecture. The pattern of laminar connections with V1, V2, and V3 indicated that MT projects "back" to these areas and they project "forward" to MT. That is, the projections to these areas from MT terminated in both the supragranular and infragranular layers and the projections to MT from these areas originated predominantly from cells located above granular layer IV (above layer IVC in V1).(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗
PubMed1986

Regional distribution of [3H]naloxone binding in the brain of a newborn rhesus monkey.

The distribution of opiate receptors in the brain of a newborn monkey (Macaca mulatta) was mapped by in vitro autoradiographic localization of [3H]naloxone binding to tissue sections. The autoradiographs of the newborn brain were compared to those from two adult brains. The distribution of opiate receptors appeared to be adult-like in subcortical structures (both limbic and nonlimbic) and allocortical areas. By contrast, all neocortical areas, except the primary visual cortex, lacked at birth the laminar specific patterns that characterize the adult. The results therefore suggest that, like many other aspects of neocortical maturation, such as dendritic growth, synaptogenesis, myelination and neurotransmitter concentrations, the distribution of opiate receptors continues to develop postnatally.

Animals↗
PubMed1979

The striate projection zone in the superior temporal sulcus of Macaca mulatta: location and topographic organization.

In the rhesus monkey, the caudal portion of the superior temporal sulcus (STS) receives a direct projection from lateral striate cortex, the striate are representing central vision. The present study was undertaken to determine whether STS also receives a direct projection from areas of striate cortex representing peripheral vision, with the intent of defining the entire striate projection zone in STS as well as providing information regarding a possible topographic organization within this secondary visual area. A series of five rhesus monkeys was prepared with unilateral lesions of lateral, posterior, or medial striate cortex, such that, collectively, the lesions in the series included all of striate cortex with little or no invasion of prestriate cortex. The monkeys were sacrificed seven days after surgery and their brains were processed by the Fink-Heimer procedure. An analysis of the distribution of terminal degeneration within STS indicated: (1) All areas of striate cortex project to a restricted region along the caudal portion of STS. The ventral limit of this region can be demarcated by an imaginary line connecting the ventral tips of the lunate and intraparietal sulci; from this limit the region extends dorsocaudally for approximately 12 mm to the point at which STS frequently bifurcates, sending one spur forward into the inferior parietal lobule. (2) Within this portion of STS there is an orderly mapping of the visual field; progression from central vision to the far periphery is represented by a progression down the posterior bank of STS and continuing along the entire floor, or insula-like portion, of the sulcus. (3) Projections from striate cortex to STS terminate predominantly in layer IV and the deep part of layer III. (4) There is a distinctive pattern of myelination contained within the striate projection zone of STS. These anatomical findings concerning the striate projection zone of STS in the rhesus monkey are remarkably similar to those that have been described for the middle temporal visual area (MT) in New World monkeys, and thus support earlier proposals that the two areas are homologous.

Animals↗