The temporal lobes and memory

Since the first description of the case of H.M. in the mid-1950s, the debate over the contribution of the mesial temporal lobe (MTL) to human memory functioning has not ceased to stimulate new experimental work and the development of new theoretical models. The early demonstration that despite their devastating memory loss patients with hippocampal damage are still able to learn a number of visuo-motor and visuo-perceptual skills at a normal rate and to be normally primed by verbal and visual material suggested that the term "memory" is actually an umbrella concept that includes very different brain plasticity phenomena and that MTL damage actually impairs only one of these. Subsequent research, which capitalized on a detailed anatomical description of MTL structures and on the close analysis of memory-related phenomena, tried to define the unique role of the MTL structures in brain plasticity and in the government of human behavior. A first hypothesis identified this role in the conscious forms of memory as opposed to implicit ones. In the last two decades, the emphasis has moved to the relational role of the hippocampus in binding together different pieces of unimodal information to provide unitary, multimodal representations of personal experiences.