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Biomedical subjects

M Mishkin

Publications and source records attributed to M Mishkin.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1979

Role of inferior temporal cortex in interhemispheric transfer.

Neurons in inferior temporal cortex of the rhesus monkey usually have large receptive fields that extend well across the midline into both visual half-fields. The responsiveness of these neurons to stimuli in the ipsilateral visual half-field depends on the splenium and anterior commissure, the same pathways necessary for interhemispheric transfer of visual habits. Since inferior temporal neurons have the same trigger features in both half-fields and are usually binocular, they may be the site of the interhemispheric neural convergence that underlies interhemispheric transfer. If so, bilateral removal of inferior temporal cortex should interfere with interhemispheric transfer even when the commissures are intact. To test this, monkeys were trained on pattern discriminations with one eye and then tested for transfer with the other eye. Five experimental monkeys received bilateral inferior temporal lesions and, to restrict input from each eye to one hemisphere, section of the optic chiasm. Ten controls received either bilateral temporal lesions alone, chiasm section alone or remained unoperated. Only the experimental animals showed impaired transfer. These results suggest that inferior temporal neurons mediate interhemispheric transfer by providing perceptual equivalence for patterns in the left and right visual fields, and, by implication, perhaps also for patterns in different parts of the same field.

Animals↗
PubMed1978

Non-spatial memory after selective prefrontal lesions in monkeys.

Separate groups of monkeys were trained on delayed object alternation, delayed object matching, and delayed color matching, after which half the animals in each group received lesions of the cortex in the principal sulcus, and the other half, lesions of the inferior frontal convexity. The inferior convexity lesions produced severe and lasting impairments on all three tasks, perhaps as a result of the perseverative disorder that has been associated with damage to this region. By contrast, the principal sulcus lesions, which yield such severe deficits on spatial memory tasks, led to only small, transient disruptions on each of the three non-spatial tasks. According to these results, the non-spatial memory deficits that have been found after unrestricted lateral prefrontal lesions are due mainly to damage below the principal sulcus in the inferior prefrontal cortex. The function of the tissue in the principal sulcus itself, on the other hand, appears so far to be limited largely to the spatial modality.

Animals↗
PubMed1978

The locus and cytoarchitecture of the projection areas of the olfactory bulb in Macaca mulatta.

A study was made of the normal and experimental anatomy of the olfactory system of the young adult male rhesus monkey. The cytoarchitecture of the central olfactory areas was studied with cell and fiber stains, while the extent and pattern of the projections of the olfactory bulb were determined by the Fink-Heimer and autoradiographic methods. The brain of one animal that had sustained damage to the olfactory bulb two days prior to sacrifice, and of one that had a transection of the olfactory tract ten days prior to sacrifice, were processed with the Fink-Heimer technique. The first of these and four others received injections of 3H-proline or 3H-leucine into the olfactory bulb, and following a survival period of 18 hours, or 2, 4, 12, or 20 days, their brains were processed with the autoradiographic technique. The results were the same for both experimental methods and for all survival periods. The projections of the olfactory bulb in this microsmatic animal are entirely ipsilateral. All of the structures that receive direct olfactory afferents have a laminar organization except for the anterior olfactory nucleus, which is laminated only in its anterior, peduncular, portion. While the olfactory bulb projects to the entire extent and depth of the anterior olfactory nucleus, the olfactory afferents of all other structures are confined to layer IA of the plexiform layer. These structures are: all divisions of the olfactory tubercle; the frontal and temporal prepiriform cortices; the oral, medial, and dorsal divisions of the superficial amygdaloid nucleus; and polar and anterior entorhinal cortex. The rhesus monkey does not have a recognizable accessory olfactory bulb, and no projections were seen to one of its targets, the nucleus of the stria terminalis. Also, no projections were seen to the taenia tecta or the ventral division of the superficial amygdaloid nucleus. With these exceptions, the projections of the olfactory bulb in the rhesus monkey are similar to those in macrosmatic species.

Afferent Pathways↗
PubMed1978

Presumed orbital sarcoidosis: report of a case followed by computerized axial tomography and conjunctival biopsy.

A thirty-two-year old woman with known sarcoidosis was seen in the Ophthalmology Clinic because of discomfort in the left eye and orbit when looking up. A CT scan showed a small mass in the posterior left orbit. Conjunctival biopsy of the left eye showed a granuloma consistent with sarcoid. Rapid resolution of her condition occurred with prednisone therapy. One year later she had a recurrence with inability to elevate or depress the left eye. Similar, but more extensive, changes were seen on a CT scan. Conjunctival biopsy again was positive. With steroid therapy rapid and complete resolution occurred both clinically and as demonstrated by a CT scan. The relationship between her orbital mass and systemic sarcoidosis is discussed.

Adult↗
PubMed1977

Limbic and prefrontal contributions to somesthetic learning in monkeys.

Monkeys with forebrain commissurotomies and either lateral temporal, medial temporal, dorsal prefrontal, or ventral prefrontal removals from the right hemisphere were compared with control animals in learning tactual discriminations and reversal with the left hand. The lateral temporal removal yielded no effect, confirming the modality-specific roles of this sector in audition (superior temporal gyrus) and vision (inferior temporal gyrus). The dorsal prefrontal removed yielded a deficit in discrimination learning, possibly as a result of the contralateral sensory neglect or the spatial disorder produced by this lesion. Each of the two remaining lesions, medial temporal and ventral prefrontal, yielded deficits in both discrimination learning and reversal; and the effects of combined removal of these two limbic sectors appeared to be additive. Taken together with earlier findings in vision and audition, the results indicate that the two limbic sectors contribute to learning in all sensory modalities, and that they do so through cortico-cortical interaction with the sensory systems.

Animals↗
PubMed1977

Contributions of the corpus callosum and the anterior commissure to visual activation of inferior temporal neurons.

Most neurons in the inferior temporal cortex of the rhesus monkeys have visual receptive fields that extend across the vertical meridian well into both the contralateral and ipsilateral visual half-fields. We examined the role of different portions of the forebrain commissures in providing the ipsilateral input with the following results. (1) Combined section of the splenium and anterior commissure eliminated visual activation from the ipsilateral visual half-field. (2) Section of the splenium, with sparing of the anterior commissure, reduced the incidence of ipsilateral activation by about one-half. (3) Section of the anterior commissure, with sparing of the splenium, did not alter the incidence of ipsilateral activation. (4) Section of the non-splenial portions of the corpus callosum had no effect on the laterality of the receptive fields. Thus, both the splenium and the anterior commissure but not the non-splenial callosum can provide information from the ipsilateral visual field to neurons in inferior temporal cortex. These results are interpreted as suggesting that the converging input from the two visual half-fields onto single inferior temporal neurons provided by the forebrain commissures may mediate interhemispheric transfer of visual habits.

Animals↗
PubMed1977

Pattern discrimination thresholds after partial inferior temporal or lateral striate lesions in monkeys.

Ablation of inferior temporal (IT) cortex, particularly of the posterior region, produces severe impairment in pattern discrimination learning. The present study examined whether this impairment is associated with raised pattern discrimination thresholds. Groups of three monkeys each were given either anterior IT, posterior IT, or foveal striate lesions, or kept as controls. They were trained after surgery on a threshold task in which a 90 degrees white angle on a gray ground was the standard, and 15 angles ranging from 10 degrees through 88.5 degrees were the comparisons. As expected, monkeys with posterior IT lesions were the most severely impaired in learning the initial discrimination (90 degrees vs. 10 degrees). However, only the monkeys with foveal striate lesions showed significant impairment on the subsequent threshold determinations. The results indicate that raised pattern discrimination thresholds are not the cause of the pattern discrimination learning deficits produced by inferior temporal lesions. Data from additional visual discriminations presented after threshold testing was completed point, instead, to a loss of attention to stimulus features as the explanation for the learning deficit.

Animals↗
PubMed1976

Effect of cardiac arrest on cerebral circulation. An experimental investigation.

The effect of 2 to 15 min of cardiac arrest on cerebral circulation was investigated in dogs and Rhesus monkeys. When circulatory arrest lasted longer than 5 minutes, angiographic changes of the no-reflow phenomenon were observed between 3 and 4 h after resuscitation in dogs but not in monkeys. These findings were (1) marked prolongation of the arterial phase in both intracranial and extracranial arteries; followed by (2) occasional evidence of dilatation of the proximal intracranial arteries with non-filling of the distal intracranial arteries; and (3) faint demonstration of the venous phase. Carbon black perfusion results were (1) diffuse lack of perfusion at the arteriolar-capillary level and (2) multifocal areas of filling defects. Regional cortical blood flow measurement in monkeys disclosed a significant decrease in flow starting from 3 h after re-establishment of circulation for those in which longer than 5 min of arrest was induced.

Animals↗
PubMed1975

An analysis of short-term visual memory in the monkey.

Visual memory in monkeys was examined under four different conditions, each with a separate group. In all conditions, the delay between sample and choice was 10 sec, and the delay between trials was 30 sec. The procedural differences were matching or nonmatching with the same two objects presented repeatedly and matching or nonmatching with trial-unique objects. With the customary repetitive stimuli, whether in matching or nonmatching, most monkeys either required prolonged training to solve the problem (over 40 sessions) or failed to solve it, corroborating the learning difficulties reported earlier by others. With trial-unique stimuli, by contrast, most monkeys learned quickly (matching, under 20 sessions; nonmatching, under 5 sessions). Furthermore, in nonmatching with trial-unique stimuli, scores averaged 80% correct in the first session, even though the monkeys were experimentally naive. The results indicate that recognition of a stimulus as familiar or novel is highly developed in monkeys, and that their difficulty with the customary nonspatial visual memory tasks stems from a retardation in noticing and using the mnemonic cue of recovery of presentation. Evidence is presented that this difficulty can be overcome, however, by a simple training procedure that exploits their proficiency at distinguishing familiar from novel stimuli.

Animals↗