Regional dissociations within the hippocampus—memory and anxiety
D.M. Bannermana, J.N.P. Rawlinsa,*, S.B. McHugha, R.M.J. Deacona, B.K. Yeeb, T. Bastb,1,
W.-N. Zhangb, H.H.J. Pothuizenb, J. Feldonb
aDepartment of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK
bLaboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, Schwerzenbach CH-8603, Switzerland
The amnestic effects of hippocampal lesions are well documented, leading to numerous memory-based theories of hippocampal
function. It is debatable, however, whether any one of these theories can satisfactorily account for all the consequences of
hippocampal damage: Hippocampal lesions also result in behavioural disinhibition and reduced anxiety. A growing number of studies
now suggest that these diverse behavioural effects may be associated with different hippocampal subregions. There is evidence for at
least two distinct functional domains, although recent neuroanatomical studies suggest this may be an underestimate. Selective lesion
studies show that the hippocampus is functionally subdivided along the septotemporal axis into dorsal and ventral regions, each
associated with a distinct set of behaviours. Dorsal hippocampus has a preferential role in certain forms of learning and memory,
notably spatial learning, but ventral hippocampus may have a preferential role in brain processes associated with anxiety-related
behaviours. The latter’s role in emotional processing is also distinct from that of the amygdala, which is associated specifically with
fear. Gray and McNaughton’s theory can in principle incorporate these apparently distinct hippocampal functions, and provides a
plausible unitary account for the multiple facets of hippocampal function.
q 2004 Elsevier Ltd. All rights reserved.
Keywords: Hippocampus; Dorsal; Ventral; Amygdala; Spatial; Learning; Memory; Anxiety; Fear; Freezing; Startle
1. Preferentially dorsal hippocampus-dependent functions . . .