Project Details


Patients with anterior communicating artery (ACoA) aneurysm often show an
anterograde amnesia syndrome: relatively poor ability to form new memories
but relative sparing of older memories (e.g., DeLuca and Diamond, 1995).
ACoA amnesia is thus superficially similar to the amnesia which may follow
damage to the hippocampus and associated medial temporal (MT) structure
(e.g., Squire, 1987), although the ACoA amnesics have no direct MT damage.
Animal models, pharmacological data, and computational models suggest that
basal forebrain structures modulate hippocampal processing, leading to
disrupted hippocampal processing in ACoA amnesia (e.g., Myers et al.,
1996). However, these models also predict subtle differences in residual
memory abilities following basal forebrain versus MT damage (e.g., Myers
et al., 1996).

This work proposes testing a population of ACoA amnesic (and appropriate
matched controls) on a series of associative learning tasks of the kind
known to be impaired or spared in MT amnesia and hippocampal-lesioned
animals. These include motor-reflex conditioning of the eye-blink
responses and computer-based operant conditioning tasks. Whereas simple
conditioning is spared in MT amnesia, but more complex conditioning
involving contextual or configural information is impaired, we expect the
opposite pattern of results to obtain in the ACoA amnesics. If this
prediction hods, these results will represent evidence differentiating the
memory deficit in these two populations. This will inform current
understanding of how hippocampus and basal forebrain interact in normal
memory. Additionally, a battery of tasks which are sensitive to basal
forebrain damage would be useful in a assessing lesion extent in ACoA
amnesics, for whom neuroimaging is typically inconclusive. Finally, this
study represents an opportunity for the PI, trained in computational
modeling of memory systems, to gain new experience and training in
clinical behavioral studies through collaboration with Drs. DeLuca and
Diamond, who have extensive experience working with ACoA aneurysm
survivors and ACoA amnesia.
Effective start/end date3/10/982/28/99


  • National Institute of Mental Health


  • Surgery


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