Affiliations: Department of Psychology, Institute of Psychiatry, De
Crespigny Park, Denmark Hill, London SE5 8AF, UK.
Note: [] Corresponding author: Department of Psychology, Goldsmiths
College, University of London, New Cross, London SE14 6NW, UK. Tel.: +44 20
7919 7194; Fax: +44 20 7919 7877; E-mail: [email protected].
Abstract: Anterograde amnesia, a common consequence of transient cerebral
ischaemia, has been attributed to cell loss in the hippocampal CA1 subfield.
However, variable, widespread damage outside hippocampal CA1 can also occur
following ischaemia. We compared the functional consequences of ischaemia and
ibotenate acid CA1 lesions on 2 spatial memory tasks (water maze 'place' and
'matching-to-position') to address the possibility that extra-CA1 loss
contributes to ischaemia-induced memory deficits in the rat. During place task
acquisition, ischaemic rats showed deficits on more measures than ibotenic
rats, and during a 1 min probe trial, only ischaemic rats were impaired. On
the matching-to-position task, ibotenic rats showed greater impairment than
ischaemic rats in terms of one-trial learning, whereas ischaemic rats were more
impaired after Trial 2. Ischaemia and ibotenic acid lesions resulted in
equivalent CA1 loss, but silver impregnation revealed additional extra-CA1 cell
loss in ischaemic rats. Together with the greater behavioural deficits of
ischaemic rats, these data indicate a role for extra-CA1 cell loss in
ischaemia-induced memory impairments in both animals and humans.
Keywords: Anterograde amnesia, global ischaemia, ibotenic acid, hippocampus, CA1, water maze, silver impregnation
