Biomedical subjects

M A Jeeves

Publications and source records attributed to M A Jeeves.

36 records · Page 2Linked to original sources

PubMed1985

Visual cells in the temporal cortex sensitive to face view and gaze direction.

The direction of eye gaze and orientation of the face towards or away from another are important social signals for man and for macaque monkey. We have studied the effects of these signals in a region of the macaque temporal cortex where cells have been found to be responsive to the sight of faces. Of cells selectively responsive to the sight of the face or head but not to other objects (182 cells) 63% were sensitive to the orientation of the head. Different views of the head (full face, profile, back or top of the head, face rotated by 45 degrees up to the ceiling or down to the floor) maximally activated different classes of cell. All classes of cell, however, remained active as the preferred view was rotated isomorphically or was changed in size or distance. Isomorphic rotation by 90-180 degrees increased cell response latencies by 10-60 ms. Sensitivity to gaze direction was found for 64% of the cells tested that were tuned to head orientation. Eighteen cells most responsive to the full face preferred eye contact, while 18 cells tuned to the profile face preferred averted gaze. Sensitivity to gaze was thus compatible with, but could be independent of, sensitivity to head orientation. Results suggest that the recognition of one type of object may proceed via the independent high level analysis of several restricted views of the object (viewer-centred descriptions).

Animals↗

PubMed1985

Reaction times to lateralized visual stimuli in callosal agenesis: stimulus and response factors.

A young acallosal man was intensively tested in a standard simple reaction time (RT) paradigm using briefly-presented lateralized spots for light. In Experiment 1, findings on previous acallosal patients of a large disadvantage for crossed (e.g. right hemifield-left hand) as against uncrossed (e.g. left hemifield-left hand) RTs were replicated. This crossed-uncrossed difference (CUD), as in previous work, turned out to be smaller in a bimanual response task than in the conventional unimanual task. Experiment 2 was a factorial study of unimanual RTs in which (a) stimulus intensity and (b) spatial S-R compatibility, were varied. As in a previously tested patient, decreased intensity resulted in a greatly increased CUD. S-R compatibility on the other hand had no effect on CUD. The results are interpreted as favouring a role for visual commissural neurones in the acallosal CUD, and as evidence against a spatial compatibility hypothesis.

Adult↗

PubMed1985

Visual analysis of body movements by neurones in the temporal cortex of the macaque monkey: a preliminary report.

Movement provides biologically important information about the nature (and intent) of animate objects. We have studied cells in the superior temporal sulcus of the macaque monkey which seem to process such visual information. We found that the majority of cells in this brain region were selective for type of movement and for stimulus form, most cells responding only to particular movements of the body or some part of it. A variety of cell types emerged, including cells sensitive to: translation of bodies in view, movements into view (appearance) or out of view (disappearance) and the articulation and rotation of the body/head. Directional selectivity for cells sensitive to translation tended to lie along one of 3 orthogonal Cartesian axes centred on the monkey (towards/away, left/right and up/down). One type of rotation sensitive cell was tuned to rotation about one or more of these axes, a second type was sensitive to different head rotations which brought the face to confront the monkey or turned the face away. Reconstructions of cell positions indicated that cells of the same type were clumped anatomically both across the surface of the cortex and perpendicular to the surface.

Animals↗

PubMed1984

Behaviour disturbance and mental handicap: typology and longitudinal trends.

Behaviour disturbance was investigated in mentally handicapped adults who were living in hospital or at home. The first part of the study describes an empirically derived typology of disturbed behaviour patterns and gives the details of a scale by means of which behaviour disturbance can be quantified along six dimensions: aggression, mood disturbance, communicativeness, antisocial conduct, idiosyncratic mannerisms, and self-injury. The second part of the study used the scale in a longitudinal study of behavioural disturbance. Different forms of disturbed behaviour exhibited different kinds of longitudinal stability, and the long-term changes in one aspect of disturbance depended on subjects' other disturbance scores.

Adolescent↗

PubMed1984

The historical roots and recurring issues of neurobiological studies of face perception.

Evidence concerning the neurobiological basis of face perception is converging from three directions. First, there are studies of neurological patients who present with specific difficulties in the recognition of familiar faces. Second, there are neuropsychological studies of face perception in normal people which identify some of the psychological mechanisms involved in face perception. Thirdly, there are neurophysiological studies in non-human primates which point to specific neural mechanisms which selectively process faces. A review of the literature from these three distinct areas of research suggests that there may indeed be something quite specific about the neural mechanisms selectively processing faces. The evidence from cognitive neuropsychology indicating a hierarchy of stages involved in visual processing and visual recognition suggests that where there is difficulty in recognizing familiar faces resulting from brain damage, the precise nature of the difficulty may depend upon which stage or stages in this hierarchy have been most affected. This in turn will reflect the particular localisation of the lesions that have been sustained.

Agnosia↗

PubMed1984

Neurones responsive to faces in the temporal cortex: studies of functional organization, sensitivity to identity and relation to perception.

We have investigated the distribution of cells responsive to faces within the macaque temporal cortex and their sensitivity to different face attributes. We found a functional organization of cells responsive to the sight of different views of the head. Cells of a similar type were grouped together both vertically down through the cortex, and horizontally in patches extending 0.5-2.0 mm across the surface of the cortex. A substantial proportion of cells responsive to faces were found to be sensitive to biologically important characteristics such as identity or expression. Cells were found to be highly selective for particular individuals that were familiar to the monkey with selectivity persisting across a great variety of viewing conditions such as changing face expression, orientation, colour, distance and size. Data suggested that sensitivity to identity arises at the level of specific views of the individual (e.g. full face). Information about different views may then be pooled to allow recognition independent of view. Visual transformations that make it difficult for humans to perceive faces (e.g., contrast reversal, isoluminant colour, coarsely quantized images, rotation or inversion) reduced the magnitude or increased the latency of cells' responses to faces. In this way, cell responses were related to perception and not simply to visual qualities of the image.

Adolescent↗

PubMed1982

Interference effects of verbal and spatial tasks on simple visual reaction time.

Simple reaction times to lateralized light flash stimulation were measured in normal right-handers either with or without a concurrent task. In agreement with a previous report, a counting backwards task resulted in a substantial RT slowing which affected right-side stimuli more than left. Contrary to expectation, however, a tactual orientation discrimination task resulted in RT slowing which affected right-hand responses more than left, with no visual asymmetry.

Adult↗

PubMed1981

Social familiarity and communication in Down syndrome.

The communication of eight Down syndrome individuals with strangers and with acquaintances was analysed. The spontaneity of their speech and the communicative demands they made on their audiences were found to be low. Some of them broke rules of conversation by not answering questions. Surprisingly, their speech was not more spontaneous with acquaintances. It was further observed that Down syndrome individuals' conversations were in the main restricted to comments on current actions. However, different postures are adopted and different body mobility exhibited depending on partner familiarity. It is concluded that Down syndrome persons prefer to express intimacy/social distance in non-verbal modalities.

Adolescent↗

PubMed1979

Functional consequences of the transcallosal removal of intraventricular tumours.

Colloid cysts and other benign tumours of the third and lateral ventricles may be exposed through a small incision in the body of the corpus callosum. This approach is practicable even when ventricular dilatation is slight, and is theoretically less likely to cause epilepsy than the more usual transcortical approach. Disturbances of memory have been noted soon after such operations, but do not cause serious long-term disability. Three patients who underwent transcallosal removal of cysts or tumours some years earlier have been tested by procedures designed to demonstrate interhemispheric transfer of information: they were all found to have defects in transfer of tactile data, but not of information obtained visually. They were not aware of this inability, and do not appear to be inconvenienced by it. The transcallosal route is convenient. The operation sacrifices a functionally significant part of the corpus callosum, but the neurological sequelae have seemed acceptable. However, especially in the elderly, stereoventriculoscopic aspiration may be considered as the initial method of treatment.

Adolescent↗

PubMed1978

A developmental study of hemisphere specialization for recognition of faces in normal subjects.

In a developmental study of hemisphere lateralization for recognition of faces in normal subjects three groups of subjects (mean ages: 7 years 9 months; 13 years 10 months; and 19 years 6 months) were tested. The procedure was a go-no go reaction time task in which the subject responded to faces tachistoscopically presented to the right or left visual field. A left visual field superiority was found for the two older age groups, which is interpreted as a right hemisphere dominance for recognition of faces. However, the 7 and 8 year old group did not demonstrate a significant visual field difference. These results indicate that the hemisphere specialization (lateralization) for recognition of faces involves processes which develop with increasing age through childhood and is not well-established until some time after the age of 8 and before age 13.

Adolescent↗

PubMed1978

A developmental study of hemisphere specialization for alphabetical stimuli.

Three groups of normal female subjects (7 and 8 years of age, 13 and 14 years of age, and young adults) were tested on a choice reaction time task using a tachistoscopic presentation of single letters to either hemisphere. The two older groups of subjects were found to exhibit a significant right visual field (left hemisphere) superiority in reaction time to letters, but the 7 and 8 year old children did not show a hemisphere asymmetry. These reaction time results for the two older groups are consistent with Rizzolatti et al.'s (1971) finding of a right visual field superiority in reaction time to letters in male adults. The analyses of error rates for visual field differences were not significant for the children or the adolescents. In this study, in contrast to Rizzolatti et al.'s result with male adults, the female adults produced a significant visual field difference in error rate.

Adolescent↗

PubMed1977

Further studies of tactile perception and motor coordination in agenesis of the corpus callosum.

A 12-year-old female with total agenesis of the corpus callosum has been tested on several tasks involving tactile perception and motor coordination. Her performance has been compared with a group of normals of the same age and sex and a group of subjects matched for age, sex and I.Q. On 3 of the bimanual motor coordination tasks the acallosal's performance was not clearly distinguishable from the control's. She was, however, slower than the controls on the pegboard task. On a transfer of training task (formboard) the acallosal was slower than normals and did not manifest transfer. However, transfer of training was shown on a maze-learning task. No deficit was found in the ability to tactually cross-identify objects, but a deficit in tactile cross-localization was evidenced.

Adolescent↗

PubMed1975