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Abstract:
It has been suggested that in the presence of attention
orientation and color tuning curves of V4 neurons are narrower
(Spitzer, Desimone & Moran, 1988) but another study finds no
such effects (McAdams & Maunsell, 1996). We recorded from
direction-selective neurons in area MT and adjacent areas in the
superior temporal sulcus of a macaque monkey to investigate the
influence of attention on tuning to the direction of visual motion.
The monkey was trained to attend to a moving random dot pattern
(the target) in the presence of another moving random dot pattern
(the distractor) while maintaining fixation on a stationary
fixation cross. In one experimental condition the target appeared
inside the receptive field (RF) and the distractor appeared
outside. In the other condition the target appeared outside while
the distractor appeared inside the RF. Since the two conditions
employed identical sensory stimulation any response difference
between the two conditions reflects the influence of attention. We
determined the cells' tuning curves in both conditions by fitting
the responses to various directions presented inside the RF with a
Gaussian function. While for the majority of cells the response to
the preferred direction was stronger (~10-20%) when attention was
directed into the RF we found no decrease in tuning width .
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