A. Grabowska et al., MEMORY IMPAIRMENT IN PATIENTS WITH STEREOTAXIC LESIONS TO THE HIPPOCAMPUS AND AMYGDALA, Acta Neurobiologiae Experimentalis, 54(4), 1994, pp. 393-403
The study aimed at testing: (1) whether stereotaxic damage to the hipp
ocampus and amygdala results ina memory deficit, (2) whether the memor
y functions subserved by the hippocampus are lateralized and (3) wheth
er time limited storage of sensory information is impaired after focal
hippocampal and amygdalar lesions. Seven patients with unilateral ste
reotaxic damage to the anterior part of hippocampus and unilateral or
bilateral damage to the medial part of amygdala and 11 control subject
s with no brain damage participated in the research. They were present
ed with memory tests that required either remembering a spatial arrang
ement of simultaneously presented verbal vs nonverbal stimuli or a tem
poral order of sequentially presented items. Moreover, a sensory infor
mation storage test was used. The results indicate that even small dam
age limited to the anterior part of the hippocampus and medial part of
the amygdala results in a mild memory deficit. Memory impairment was
not related to the side of hippocampal lesion. This suggests that memo
ry function subserved by the hippocampus is not lateralized. Different
ial effects of left and right lobectomies found in previous studies we
re, thus, probably due to the damage to temporal cortex. The results s
howed, however, that sensory information storage limited to 3 s is not
impaired after focal damage to the hippocampus and amygdala. A clear
lateralization effect showing right hemisphere advantage in that funct
ion was found.