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 Strategies
in Visual Cortex.
The cerebral cortex embodies an interesting dichotomy in the representation
of information: on the one hand it must maintain a consistent and
reliable representation of important information, and on the other
hand it must be able to modify representations to adapt and learn.
My broad research interest is how the cortex addresses these two
potentially conflicting requirements. In particular I am interested
in how strategies based on past experiences are used in the processing
and execution of visually guided behavior.
Understanding how and why representations change in visual cortex
will provide a powerful basis for studying a number of general issues
concerning cortical information processing, including the interactions
between behavior and sensation, the mechanisms underlying learning
and development, and the neural coding of information.
Figure 1(above). Orientation change detection task.
a, Stimuli of a typical trial. Animals fixated on a central spot
throughout the trial (cross). Stimuli were located at four different
locations: two adjacent locations within the receptive field (oval,
positions 1 and 2) and opposite the receptive field (positions 3
and 4). If the animal was cued to attend to position 2 (an 'attend
in' location), it would have to release a lever when a change happened
at this location (middle and right panels), while ignoring the change
at position 4 (left and middle panels). Attentional modulation was
measured by comparing responses for visually identical trials in
which the animal attended to different locations. b, Orientation
changes occurred at random times after stimulus onset according
to the indicated probability distribution. c, The behaviourally
relevant probability is the probability that a change will occur
at a given point in time given that one has not occurred already
(hazard function). The hazard function is zero for the first 500
ms (no changes occurred) and then rises to a maximum 2.25 s after
stimulus presentation.
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