Authors:

BARENSE, M.D., Lee, A.C.H. & GRAHAM, K.S

Reference:

Year of publication:

2006

CBU number:

6520

Abstract:

The status of medial temporal lobe (MTL) regions in memory is controversial. While studies in humans suggest this region functions as a unitary memory system, animal investigations have revealed functional specialisation, with the perirhinal cortex and hippocampus playing uniqueroles in object and spatial memory, respectively. Even more contentiously, some animal experiments have highlighted a broader role for these structures in the perception of object and spatial stimuli. To address this issue, oddity tasks sensitive to MTL lesions in the nonhuman primate literature were adapted for use in human participants. Subjects were required to select the odd stimulus (scenes, faces and objects) from a visual array, a task designed to avoid the need for long-term memory. Amnesic individuals with damage limited to the hippocampus showed poor scene discrimination, but normal oddity judgement for faces and objects. Patients with broader MTL lesions, involving perirhinal cortex, were impaired on all conditions. Functional neuroimaging in healthy participants confirmed involvement of MTL regions in these discrimination paradigms, with two different networks, involving posterior hippocampus and perirhinal cortex differentially, recruited for spatial and object processing. These findings provide convergent evidence for functional specialisation within the human MTL, and highlight a critical interplay between perception and memory.