The Extended Hippocampal-Diencephalic Memory System: Enriched Housing Promotes Recovery of the Flexible Use of Spatial Representations After Anterior Thalamic Lesions
Hippocampus. 2008-10-01; 18(10): 996-1007
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1. Hippocampus. 2008;18(10):996-1007. doi: 10.1002/hipo.20457.
The extended hippocampal-diencephalic memory system: enriched housing promotes
recovery of the flexible use of spatial representations after anterior thalamic
Wolff M(1), Loukavenko EA, Will BE, Dalrymple-Alford JC.
(1)Van der Veer Institute for Parkinson’s and Brain Research, Department of
Psychology, University of Canterbury, Christchurch, New Zealand.
The anterior thalamic (AT) nuclei constitute an important component of an
extended hippocampal-diencephalic system, and severe persisting memory deficits
are normally found after AT damage. This study examined whether postoperative
enrichment promotes the recovery of the flexible use of spatial representations
in rats with AT lesions. After training to swim from a single constant start
position to a submerged platform in a Morris water maze, rats with AT lesions
that were housed in standard cages (AT-Std) performed poorly when required to
swim to the platform from novel start positions during probe trials. By contrast,
rats with AT lesions but housed in enriched environments (AT-Enr), like
sham-lesion rats, showed relatively little disruption when tested with novel
start positions. AT-Std rats also initially showed impaired acquisition of the
task, whereas AT-Enr rats learned at a similar rate to that of the Sham-Std
group. Beneficial effects of enrichment were replicated in the subsequent
standard water maze procedure that used varying start positions throughout
training to acquire a new platform location. Although it is clear that AT damage
can severely disrupt episodic-like memory processes, and appear to be a core part
of the interlinked neural systems subserving episodic memory, the current
findings strongly encourage study on the adaptive response of the brain to
thalamic lesions and prospects for the development of rehabilitation programs in
cases of anterograde amnesia associated with diencephalic injury.
PMID: 18548579 [Indexed for MEDLINE]