|CODING OF EFFECTOR AND SPACE IN MONKEY
FRONTAL EYE FIELDS (FEF).
|Washington Univ. Sch. Med, St Louis, MO,
|The FEF is traditionally thought to be
highly specific for eye movements, but recent research
has suggested that this may be true of only a subset
of FEF neurons. The activity of FEF movement cells does
appear to be tightly coupled to saccade initiation (Hanes
& Schall, 1996), but activity in FEF visual cells
can be evoked by distractors to which no saccade is
directed (Murthy et al., 2001). The notion of two subpopulations
of cells, one tightly linked to saccade production and
the other reflecting the locus of spatial attention,
is consistent with the finding that FEF micro-stimulation
can either drive saccadic eye movements or produce attention-like
modulations in V4 cells (Moore & Armstrong, 2003).
Inconsistent with this view, we previously reported
that visual, but not movement cells, are preferentially
activated by the instruction to prepare a saccade relative
to a reach (Lawrence & Snyder, 2002). This preference
was observed in the absence of spatial information.
It is possible that, in the presence of spatial information,
visual neurons may lose their effector specificity and
reflect only the locus of spatial attention. To test
this, we recorded from FEF neurons in a delayed movement
paradigm, in which both effector and spatial information
Consistent with our previous results, we found that
most visual cells with memory activity coded both spatial
and effector information during the delay period. We
call these combination cells. Their activity cannot
be explained as a correlate of spatial attention: activity
was higher during the delay period of saccade compared
to reach trials, even when the movement was directed
outside the response field. (Most movement cells were
non-responsive during the delay period, and therefore
coded neither effector nor space.) These results are
inconsistent with a generic role of visual neurons in
spatial attention. Rather, the present results suggest
that a subset of visual neurons process spatial information
in an effector-dependent manner.
Support Contributed By: NEI & EJLB
L.H. Snyder, B.M. Lawrence. CODING OF EFFECTOR AND
SPACE IN MONKEY FRONTAL EYE FIELDS (FEF). Program No.
441.1. 2003 Abstract Viewer/Itinerary Planner.
Washington, DC: Society for Neuroscience, 2003. Online.