Krauzlis Lab Projects

Superior colliculus activity during manipulations of voluntary and stimulus-driven attention

In addition to its well known role in the control of saccades, the superior colliculus (SC) has recently been implicated in target selection and visual attention. However, the allocation of attention is often confounded with saccade preparation, and the important distinction between sustained voluntary attention and transient stimulus-driven attention has not been addressed. Here, we investigated the nature of attention-related activity in neurons in the SC with a task that manipulated sustained voluntary attention using spatial cues and stimulus-driven aspects of attention using abrupt onsets.

We recorded from saccade-related neurons in the SC of a rhesus macaque trained in a 4-AFC motion discrimination task. The monkey initially fixated a central dot, and four stochastic motion patches (8.5° diameter, 8° eccentricity) were presented, one in each quadrant of the visual field. One of the four patches was momentarily cued, and after a variable delay (480-4000 msec), a brief (160 msec) pulse of coherent motion appeared in both the cued patch and the diametrically opposite patch. The direction of motion in the cued patch was randomly drawn from four possible directions (45°, 135°, 225°, 315°); the motion for the distracter patch was drawn from the remaining three directions.

On trials with abrupt onsets, the distracter patch did not appear until a variable stimulus-onset asynchrony (SOA, 160-640 msec) prior to the motion onset. After the motion pulse, the monkey was shown four choice dots and he was rewarded for making a saccade to the choice dot in the direction of motion that had appeared in the cued patch. Because the direction of motion was randomly assigned, the location of the cued patch was uncorrelated with the endpoint of the correct saccade.

In the absence of abrupt onsets, the monkey's choices correctly followed the motion in the cued patch on most trials, and ignored the motion in the distracter patch. Preliminary data from SC neurons indicates that they also show a preference for the cued patch even though it is not the target of a saccade. On trials with abrupt onsets, the monkey's choices shifted in favor of the distracter briefly after the onset event. Similarly, the activity of some SC neurons was altered by the abrupt onset with a similar time course.

These findings are consistent with the idea that SC neurons are modulated by the allocation of attention, as distinct from saccade preparation, and that they are modulated by both voluntary and stimulus-driven aspects of visual attention.

Reference:

Lovejoy, L.P., and Krauzlis, R.J. Superior colliculus activity during manipulations of voluntary and stimulus-driven attention. Society for Neuroscience Abstract, 2006.



Home: Projects: Superior colliculus activity during manipulations of voluntary and stimulus-driven attention

	Superior colliculus activity during manipulations of voluntary and stimulus-driven attention In addition to its well known role in the control of saccades, the superior colliculus (SC) has recently been implicated in target selection and visual attention. However, the allocation of attention is often confounded with saccade preparation, and the important distinction between sustained voluntary attention and transient stimulus-driven attention has not been addressed. Here, we investigated the nature of attention-related activity in neurons in the SC with a task that manipulated sustained voluntary attention using spatial cues and stimulus-driven aspects of attention using abrupt onsets. We recorded from saccade-related neurons in the SC of a rhesus macaque trained in a 4-AFC motion discrimination task. The monkey initially fixated a central dot, and four stochastic motion patches (8.5° diameter, 8° eccentricity) were presented, one in each quadrant of the visual field. One of the four patches was momentarily cued, and after a variable delay (480-4000 msec), a brief (160 msec) pulse of coherent motion appeared in both the cued patch and the diametrically opposite patch. The direction of motion in the cued patch was randomly drawn from four possible directions (45°, 135°, 225°, 315°); the motion for the distracter patch was drawn from the remaining three directions. On trials with abrupt onsets, the distracter patch did not appear until a variable stimulus-onset asynchrony (SOA, 160-640 msec) prior to the motion onset. After the motion pulse, the monkey was shown four choice dots and he was rewarded for making a saccade to the choice dot in the direction of motion that had appeared in the cued patch. Because the direction of motion was randomly assigned, the location of the cued patch was uncorrelated with the endpoint of the correct saccade. In the absence of abrupt onsets, the monkey's choices correctly followed the motion in the cued patch on most trials, and ignored the motion in the distracter patch. Preliminary data from SC neurons indicates that they also show a preference for the cued patch even though it is not the target of a saccade. On trials with abrupt onsets, the monkey's choices shifted in favor of the distracter briefly after the onset event. Similarly, the activity of some SC neurons was altered by the abrupt onset with a similar time course. These findings are consistent with the idea that SC neurons are modulated by the allocation of attention, as distinct from saccade preparation, and that they are modulated by both voluntary and stimulus-driven aspects of visual attention. Reference: Lovejoy, L.P., and Krauzlis, R.J. Superior colliculus activity during manipulations of voluntary and stimulus-driven attention. Society for Neuroscience Abstract, 2006.
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