 Gatsby Computational
Neuroscience UnitAlexandra House, 17 Queen Square, LONDON, WC1N 3AR, UK, Tel: +44 (0) 20 7679 1176, Fax +44 (0) 20 7679 1173 abla@gatsby.ucl.ac.uk, www.gatsby.ucl.ac.uk ABSTRACTS Supported by The Gatsby Foundation |Index|Objective|Attendees|Programme|Travel information|Accommodation| The Effects of Cholinergic and Noradrenergic Deafferentation of the Cortex on Memory and Attention
Jill McGaughy, Michael Hasselmo
and Howard Eichenbaum
Normal and pathological
aging is correlated with degeneration in both the cholinergic and
noradrenergic systems. The importance of the cholinergic system in
sustained and divided attention has been well supported in recent
years. However, less is known about the role of ACh in other types of
cognition or the role of NE in attention. In
humans, the medial temporal lobes are specifically activated during
working memory for novel, but not familiar stimuli (Stern et al. 2001)
and cholinergic deafferentation of the rhinal cortex in non-human
primates has been shown to impair memory for trial-unique (novel)
stimuli (Turchi et al. SFN abstracts v. 28). Currently, the effects of
cholinergic deafferentation of the entorhinal cortex (EC) were tested
in an odor, delayed non-match to sample task (DNMS) using rats. Rats
were impaired in recognition memory for novel, but not familiar odors.
The impairment cannot be explained by an increased sensitivity
to task difficulty as a result of the lesion. These data support the
hypothesis that cholinergic afferents to the EC activate cellular
mechanisms of sustained spiking activity necessary for maintenance of
novel, but not familiar stimuli in a working memory task (Fransen et
al. 2002). In a second study, the effects of noradrenergic or
cholinergic deafferentation of the infralimbic/prelimbic cortex of
rats in an attentional set-shifting task (Birrell and Brown 2000) were
examined. The noradrenergic lesions caused impairments in the
broadening of attentional scope necessary to attend to a newly
relevant stimuli dimension (extra-dimensional shift) but did not
affect other aspects of the task. Lesions of the cholinergic afferents
did not alter attentional set-shifting but impaired the ability to
inhibit responding to novel, but irrelevant stimuli. These data do not
support a simple dissociation of the effects of ACh and NE on
cognition along temporal or spatial dimensions and highlight the need
to consider the functions of these systems based on their termination
rather than origin.
Birrell J, Brown V (2000)
Fransen, E, Alonso, AA and
Hasselmo, ME (2002)
Stern CE, Sherman SJ,
Kirchhoff BA, Hasselmo ME (2001)
Turchi, JN, Saunders, RC,
Mishkin, M (2002) |