Hippocampus and recognition memory

A long-standing interest in the lab has been the role of the hippocampus in recognition memory. Dual process theories suggest that recognition memory tasks can be solved both by familiarity and by recollection, and that the hippocampus is required only for recollection. Consistent with this view, many studies have shown that recognition of individual items (e.g. objects) does not require the hippocampus, whereas associative recognition of objects and their allocentric locations or the order in which they occur is hippocampus-dependent. To explore the role of the hippocampus further in associative recognition processes, we have made use of variants of the spontaneous object exploration task for rats recently developed by Eacott and colleagues, illustrated below.

Bilateral lesions of the hippocampus encompassing the whole septal-temporal extent of the structure result in selective deficits on the Object-Place-Context task, while sparing recognition of objects, or object-context and object-place associations (Langston & Wood, 2010). A similar pattern is seen with selective lesions of either CA1 or CA3 (Langston, Stevenson et al., 2010). These data suggest that, rather than being required for all types of associative recognition, the hippocampus is required only for specific associations (in this case between objects, their locations, and the contexts in which they occurred). Moreover, processing in the trisynaptic loop is required. Why this selectivity? One possibility is that the hippocampus (possibly CA3) is the anatomical location in which object, location and contextual information are integrated rapidly, whereas object and (egocentric) location, as well as object and context information can be integrated at other brain locations.

Using spontaneous recognition memory tasks to probe episodic-like and familiarity-based memory function in disease models

We have started using the suite of tasks described above to probe function in mouse and rat models of neurodegenerative and neurodevelopmental disorders such as Alzheimer's Disease (in collaboration with Dr Karen Horsburgh) and Fragile X (in collaboration with Prof Peter Kind and members of the Patrick Wild Centre). Check back here in the coming months for progress on these projects .....