Multiple myeloma, nephrotic syndrome and crystalloid inclusions in podocytes.
Explore the source record for details and available documents.
Acute Kidney Injury↗
Biomedical subjects
D C Preddie
Publications and source records attributed to D C Preddie.
Spatial attention effects in macaque area V4.
Focal visual attention typically produces enhanced perceptual processing at the psychological level and relatively stronger neural responses at the physiological level. A longstanding mechanistic question is whether these attentional effects pertain specifically to the attended (target) object or to the region of space it occupies. We show here that attentional response enhancement in macaque area V4 extends to behaviorally irrelevant objects in the vicinity of the target object, indicating that focal attention has a strong spatial component at the physiological level. In addition, we find that spatial attention effects typically show a striking directional asymmetry. The direction of the asymmetry varies between cells, so that some cells respond best when attention is directed to the left of the stimulus, some when attention is directed to the right, etc. Thus, attention involves not only enhanced responses to behavioral targets but also a complex modulation of responses to other stimuli in the surrounding visual space.
Animals↗
Responses in area V4 depend on the spatial relationship between stimulus and attention.
1. We studied the spatial interaction between stimulus and attention in macaque area V4. Monkeys were required to fixate a small spot while continuously attending to a ring-shaped target within a large array of identical rings. Meanwhile, the response of the V4 cell under study was tested by flashing behaviorally irrelevant bar stimuli in the cell's classical receptive field (CRF). The location of the attended ring was varied across four positions surrounding the CRF, and the location of the bar stimulus was varied across five positions spanning the CRF. 2. Response strength depended on two aspects of the spatial relationship between the stimulus driving the cell (the bar) and the position of attention (the target ring). First, for 49% of the cells studied, responses were greater for bar stimuli near the attended ring; i.e., the receptive field profile shifted toward the attentional focus. Second, for 84% of the cells, the overall response level depended on the direction in which attention lay relative to the stimulus in the CRF (e.g., to the left, right, above, or below). 3. This study confirms a key prediction of spatial models of attention, which postulate enhanced processing of all stimuli near the attentional focus. It also introduces the novel finding that responses are influenced by the relative direction of attention. This result indicates that area V4 carries information about the spatial relationship between visual stimuli and attention.
Animals↗