Chapter 5.1 Memory and perceptual impairments in amnesia and dementia

Recent findings from animal and human studies of memory have challenged existing accounts of the role of the medial temporal lobe (MTL) in human long-term declarative memory. These studies indicate that the MTL is not exclusively specialized for declarative long-term memory, with evidence of impairments in short-term memory and perceptual discrimination in patients with progressive and nonprogressive MTL damage. These deficits have been elicited by the increased use of paradigms developed from the animal literature which have highlighted two key factors that seem to differentially influence performance after MTL lesions: (a) whether participants are asked to perceive and remember scenes vs. objects/faces; and (b) the use of simple or complex feature ambiguous stimuli. Functional neuroimaging in healthy participants using similar paradigms has provided convergent evidence for these neuropsychological studies, revealing differential activation of two distinct networks involving different MTL regions during face and scene processing. These results are discussed with respect to existing models of the role of human MTL regions in long-term memory