The Journal of Neuroscience, November 15, 1999, 19(22):10135-10139
Attentional Orienting Is Impaired by Unilateral Lesions of the
Thalamic Reticular Nucleus in the Rat
G. Daniel
Weese1,
Janice M.
Phillips2, and
Verity J.
Brown2
1 Department of Psychology, Hampden-Sydney College,
Hampden-Sydney, Virginia 23943, and 2 School of Psychology,
University of St. Andrews, St. Andrews KY16 9JU, Scotland, United
Kingdom
The thalamic reticular nucleus (TRN) has been implicated in
attentional processes based on its anatomical, electrophysiological, and neurochemical relationships with the sensory nuclei of the thalamus
and corresponding sensory areas of cortex. This study examined the
possibility that the TRN is involved in covert orienting of attention.
Attention can be summoned to a spatial location in the absence of an
overt orienting response. The reaction time to a visual target is
faster when attention has been drawn to the location of the target by a
preceding cue in that location (valid cue) compared with when the cue
misdirects attention (invalid cue) away from the location of the
subsequent target. This reaction time difference is referred to as the
"validity effect."
Rats were trained to perform such a reaction time task with visual cues
and targets presented in poke holes to either side of the rat's head,
which had to be maintained centrally and still. If the rat made an
overt orienting response to the cue, the trial was aborted. Unilateral
lesions were made by injection of ibotenic acid in the TRN. After
surgery, there was no bias apparent in their responding; they were as
likely to initiate responses and were equally accurate to either side.
There was, however, a complete abolition of the validity effect for
responses to contralateral targets. The data are discussed in terms of
a role for the TRN in attentional processing.
Key words:
attention; orienting; neglect; thalamic reticular
nucleus; ibotenic acid; rat
Copyright © 1999 Society for Neuroscience 0270-6474/99/192210135-05$05.00/0