Decision-related activity in the macaque dorsal visual pathway
A. Thiele, C. Distler & K.-P. Hoffmann
European Journal of Neuroscience, 11:2044-2058, 1999
- Brain areas at higher levels of cortical organization are thought to be more involved in decision processes
than are earlier, i.e. lower, sensory areas. Hence, neuronal activity correlated with decisions should vary with
an area's position in the cortical hierarchy. To test this proposal, we investigated whether a change in neuronal
activity during error trials depends in a systematic way on cortical hierarchical position. While macaque monkeys
discriminated the direction of moving visual stimuli, the activity of direction-selective neurons was recorded
in four extrastriate visual areas: V3A, the middle temporal area, the middle superior temporal area and the posterior
part of the superior temporal polysensory area. Neuronal activity was significantly reduced in all areas when the
monkeys made errors in judging the direction of stimuli moving in the preferred direction with low and intermediate
luminance contrast. The amount of activity reduction was approximately 50% in all of the visual areas. Thus, the
activity on error trials is reduced in early visual processing, independent of the hierarchy in the dorsal visual
pathway. The activity reduction depended on stimulus contrast and the direction of the decision relative to the
stimulus motion. It was profound and significant in all areas at low stimulus contrast. However, it was nonsignificant
at high stimulus contrast. Our data suggest that activity reduction on error trials is due to lack of attention
in association with stimulus expectation.
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