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Monday April 6th, 2009 from 17:00 to 18:00
Location: Auditoire Maisin, UCL Brussels
by Michael E. Goldberg, - David Mahoney Professor of Brain & Behavior, Neuroscience, Neurology, Psychiatry, Ophthalmology;
- Director, Mohoney Center;
- Department of Neuroscience, Columbia Univ., New York, USA.
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Abstract:
On the agnosticism of spikes: saccades and attention in the lateral intraparietal area of the monkey.
There has been a debate about the role of the parietal cortex in
the generation of movements. The lateral intraparietal area (LIP) is
important in the brain’s processing of eye movements, and the LIP
version of the debate is whether it actually drives the movements
(‘intention’) or selects targets for further processing (‘attention’).
Under different circumstances, both concepts are correct: If a
distractor appears while a monkey plans a memory-guided saccade
elsewhere, the monkey’s attention, as measured by perceptual threshold,
moves from the goal of the saccade, and then returns. The activity of
neurons in LIP predict the monkey’s attention even when the locus of
attention is away from the saccade goal. Conversely, under conditions
of visual search, the activity of LIP neurons predicts the goal and
reaction time of eye movements. I will propose that LIP represents a
priority map of visual space. The oculomotor system uses this map to
choose the target of the next saccade, when saccades are appropriate.
The visual system uses the same map to determine the locus of visual
attention. The map is created by the combination of visual, oculomotor
and cognitive signals, among others, and the spikes lose the identity
of their genesis - spikes originating in the oculomotor system can
drive attention; spikes originating from the abrupt onset of visual
stimuli can drive express saccades.
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last update: March 12th, 2009
Author: Philippe LEFEVRE
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