We studied a group of 31 temporal lobe epilepsy
patients (25 left, 6 right) with unilateral hippocampal
sclerosis evident on magnetic resonance imaging. Single
slice T2 relaxation times were acquired for the left and
right hippocampi. Principal components analysis of preoperative
memory data resulted in two factors that reflect a distinction
between arbitrary and semantic forms of verbal recall.
The former component correlated with left hippocampal T2
relaxation time, while the latter component did not. This
study suggests that variation in left hippocampal integrity
is more related to the acquisition of arbitrary associates
than semantically structured material, and reinforces the
possibility that the left temporal lobe is functionally
heterogeneous with respect to memory. (JINS, 2000,
6, 529–538.)