Project: Research project


We will investigate the neurobiology of preparatory set in order to
isolate the cognitive components, and their neural substrates, of
those brain switching mechanisms which enable humans to respond
flexibly and efficiently to their environment. Reaction time (RT)
experiments will be conducted in normal humans and neurological
patients to separate the cortical and subcortical components of
perceptual and motor preparatory set. The tasks are similar to
those which have been employed in unit recordings in animal
experiments for identifying selective enhancement related to
preparatory set, so that the two strands of research may begin to
converge. The perceptual set tasks involve a simple RT manual
response on detecting a luminance changes in the visual field; the
motor set tasks involve choice RT manual movements. For both
tasks, preparatory set is induced by a preliminary visual cue which
instructs the subject where to expect the target or which
movement to prepare. Preparatory set is inferred, and its time
course measured, on the basis of facilitation or inhibition in RT
performance depending upon whether the cue correctly prepares
the subject for the subsequent target. We will measure convert
orienting in patients with progressive supranuclear palsy, and
compare orienting into temporal and nasal hemifields in normal
subjects, to test the hypotheses that midbrain centers are
involved both in moving attention to exogenous signals, and in
coordinating attention with eye movements. Experiments in
patients with frontal and caudate lesions will test the hypothesis
that these structures are involved in moving attention under
endogenous control. Experiments in patients with thalamic
lesions will test the hypothesis that the pulvinar is involved in
engaging attention at a new location. Experiments in patients
with Parkinson's disease, frontal lobe and cerebellar lesions will
investigate the role of cortical and subcortical centers in
mediating motor set. While the primary importance of this
research lies in its potential for elucidating a fundamental
problem in neurobiology, it also has potential clinical relevance as
well. It may lead to more rational approaches to the
rehabilitation of patients with attention and motor planning
disorders due to neurological diseases.
Effective start/end date4/1/886/30/02


  • National Institutes of Health
  • National Institutes of Health: $167,850.00
  • National Institutes of Health


Mental Disorders
Frontal Lobe
Visual Cortex
Prefrontal Cortex
Inhibition (Psychology)


  • Medicine(all)