David Lee Robinson

The pulvinar and visual salience

One of the major problems of living in a rich visual environment is deciding which particular object or location should be chosen for complete processing or attention; that is, deciding which object is most salient at any particular time. The pulvinar has enlarged substantially during evolution, although little has previously been known about its function. Recent studies suggest that the pulvinar contains neurons that generate signals related to the salience of visual objects. This evidence includes: (1) anatomical and physiological observations of visual function; (2) augmented responses in the pulvinar for visual stimuli presented in important contexts; (3) suppression of activity for stimuli presented in irrelevant conditions; (4) thalamic modulation producing behavioral changes in cued attention paradigms; and (5) similar changes with visual distracter tasks.

Single axon analysis of pulvinocortical connections to several visual areas in the Macaque

The pulvinar nucleus is a major source of input to visual cortical areas, but many important facts are still unknown concerning the organization of pulvinocortical (PC) connections and their possible interactions with other connectional systems. In order to address some of these questions, we labeled PC connections by extracellular injections of biotinylated dextran amine into the lateral pulvinar of two monkeys, and analyzed 25 individual axons in several extrastriate areas by serial section reconstruction. This approach yielded four results: (1) in all extrastriate areas examined (V2, V3, V4, and middle temporal area [MT]/V5), PC axons consistently have 2–6 multiple, spatially distributed arbors; (2) in each area, there is a small number of larger caliber axons, possibly originating from a subpopulation of calbindin‐positive giant projection neurons in the pulvinar; (3) as previously reported by others, most terminations in extrastriate areas are concentrated in layer 3, but they can occur in other layers (layers 4,5,6, and, occasionally, layer 1) as collaterals of a single axon; in addition, (4) the size of individual arbors and of the terminal field as a whole varies with cortical area. In areas V2 and V3, there is typically a single principal arbor (0.25–0.50 mm in diameter) and several smaller arbors. In area V4, the principal arbor is larger (2.0‐ to 2.5‐mm‐wide), but in area MT/V5, the arbors tend to be smaller (0.15 mm in diameter). Size differences might result from specializations of the target areas, or may be more related to the particular injection site and how this projects to individual cortical areas.

Chapter 31 Functional contributions of the primate pulvinar

Publisher Summary The pulvinar contributes to the generation of visual salience. The pulvinar works to generate salience by opposing functional mechanisms. First, it appears to suppress information, which is irrelevant. Second, it facilitates those visual data that arise in important behavioral contexts. Thus the net output of the pulvinar are signals, which would be useful for perceptual as well as effector systems. Within the anterior portion of the pulvinar, there are at least three functional regions. The first, termed the inferior map pulvina (PI), is contained entirely within the cytoarchitectural inferior pulvinar and forms a complete map of the contralateral visual field. This region receives projections from both the superior colliculus and visual cortex. The second area, labeled the lateral map (PL), is located in the cytoarchitectural lateral pulvinar adjacent to PI, contains another complete map of the visual field, and also receives collicular and visual cortical afferents. A third region, which is termed “Pdm” is also located within the cytoarchitecturally defined lateral pulvinar but has poor topography. It is interconnected with cortical areas 7, MT and PO.

Visuospatial attention: Effects of age, gender, and spatial reference

Visual attention is remarkably stable when spatial cuing is used, but non-spatial cues lead to slowing among females and older subjects. Non-spatial cues are associated with poorer performance during the middle stages of the menstrual cycle. Motivation increased overall response speed but not attentional measures, whereas increasing age was associated with generalized slowing and directional asymmetries. Right-eye dominance was correlated with slow responses to downward targets. These data suggest that attentional performance is modified by age, gender, and endocrine status when spatial reference is not present.

Saccade-related and visual activities in the pulvinar nuclei of the behaving rhesus monkey

SummaryWe studied three subdivisions of the pulvinar: a retinotopically organized inferior area (PI), a retinotopically mapped region of the lateral pulvinar (PL), and a separate, visually responsive component of the lateral pulvinar (Pdm). Single neurons were recorded in these regions from awake, trained rhesus monkeys, and we correlated the discharge patterns of the cells with eye movements. About 60% of the neurons discharged after saccadic eye movements in an illuminated environment and had either excitatory, inhibitory, or biphasic (inhibitory-excitatory) response patterns. These responses were most often transient in nature. Neurons with excitatory activity had a mean onset latency of 72 ms after the termination of the eye movement. Latencies for cells with inhibitory responses averaged 58 ms. In sharp contrast, the cells with biphasic response patterns became active before the termination of the eye movement. A unique set of these neurons termed saccade cells, were active with visually guided eye movements in the light, with the same eye movements made to a briefly pulsed target in the dark, and for similar eye movements made spontaneously in total darkness. The activity was present with the appropriate saccade, independent of the beginning eye position. Biphasic response patterns were typical of these saccade cells. Saccade cells were most common in Pdm and PI. About half of the saccade cells also had some visual response that was independent of eye movement. A second group of cells was active with saccadic eye movements in the light but not in the dark. Some of these cells had clear visual responses that could account for their activity following eye movements; others had no clear visual receptive field. Because of these and other physiological data, we propose that the saccade cells found in Pdm may function in a system dealing with visual spatial attention, while those found in PI may have a role in dealing with the visual consequences of eye movements.

Orbital position and eye movement influences on visual responses in the pulvinar nuclei of the behaving macaque

SummaryWe studied the influences of eye movements on the visual responses of neurons in two retinotopically organized areas of the pulvinar of the macaque. Cells were recorded from awake, trained monkeys, and visual responses were characterized immediately before and after the animals made saccadic eye movements. A significant proportion of the cells were more responsive to stimuli around the time of eye movements than they were at other intervals. Other cells had response reduction. For some neurons, the change in excitability was associated with orbital position and not the eye movement. For other cells the change was present with eye movements of similar amplitude and direction but with different starting and ending positions. Here it appears that the eye movement is the important parameter. Other cells had effects related to both eye position and eye movements. In all cells tested, the changes in excitability were present when the experiments were conducted in the dark as well as in the light. This suggests that the mechanism of the effect is related to the eye position or eye movement and not visual-visual interactions. For about half of the neurons with modulations, the response showed facilitation for stimuli presented in the most responsive region of the receptive field but not for those at the edge of the field. For the other cells there was facilitation throughout the field. Thus, a gradient of modulation in the receptive field may vary among cells. These experiments demonstrate modulations of visual responses in the pulvinar by eye movements. Such effects may be part of the visual-behavioral improvements at the end of eye movements and/or contribute to spatial constancy.

Dopamine dependent reaction time deficits in patients with parkinson's disease are task specific

This study tested the hypothesis that patients with Parkinsons disease are impaired when they must rely on internal information to generate a response. Choice reaction times of control subjects and patients with Parkinsons disease, on and off their medication, were measured in tasks in which the motor demands were constant but which varied in the degree to which the stimuli held intrinsic information about the required response. A dopaminergic deficit was observed only in the tasks which employed stimuli compatible with the response and not in a task employing stimuli arbitrarily associated with the response. The data do not support the hypothesis that patients are differentially impaired in using internalized stimulus-response relationships.

Latencies of visually responsive neurons in various regions of the rhesus monkey brain and their relation to human visual responses

The temporal characteristics of visually responsive neurons in a variety of areas of the monkey brain are presented. These data allow a comparison to be made between the latencies of components of the human visual ERP, and the onset latencies of neurons in regions which are candidate sources of these ERP phenomena.

Responses of pulvinar neurons to real and self-induced stimulus movement

Many neurons in the pulvinar nuclei of awake monkeys respond to real image motion while the animal maintains fixation. Many of these same cells do not discharge to comparable stimulus movement when it is caused by an eye movement. This lack of sensory response is most likely mediated by an extraretinal signal.

The Wechsler adult intelligence scale and personality assessment: Towards a biologically based theory of intelligence and cognition

Abstract Drawing on findings reported in an earlier paper (Robinson, 1985a), ‘introversion- extraversion’ scores were derived from WAIS-R profile differences. Scores on a ‘psychopathy’ dimension were derived from WAIS-R profiles in similar fashion. Results are described which show that these WAIS-R scores do relate to personality in the predicted fashion. The essential findings are that groups with high and low WAIS-R introversion-extraversion scores obtain significantly different scores on the Extraversion scale of the EPO. Groups with high and low WAIS-R psychopathy scores obtain significantly different scores on the Psychoticism scale of the same questionnaire. Some theoretical and practical implications are discussed. Special reference is made to biologically based explanations for ‘intelligence’ differences and differences in ‘cognition’.