Functional recovery after limbic lesions in monkeys.
Ten monkeys received lesions of either the hippocampus, or the amygdala and hippocampus, or the anterior and medial thalamus (each group with two monkeys), or of all these structures together with additional septal lesions (four monkeys). Postoperatively, the monkeys were trained in tasks of visual and spatial reversal, several concurrent object discriminations, delayed nonmatch-to-sample, and in an angle threshold discrimination task. Their performance was compared to that of five healthy or sham-operated control monkeys. The single- or double-lesioned monkeys were impaired in the delayed nonmatch-to-sample task and the angle threshold discrimination, whereas monkeys with five-fold lesions were unimpaired in these tasks. Correlations between brain volume loss and behavioral performance indicated negative coefficients for the delayed nonmatch-to-sample task ("delays": rs = -.59, "lists": rs = -.20) and the angle threshold discrimination (rs = -.60). It is concluded that monkeys with massive limbic lesions display a more effective postlesion reorganization than monkeys with smaller limbic lesions; however, reliability of this effect must be proved by future work with a larger sample. Furthermore, the missing impairments of massively lesioned monkeys especially in the delayed nonmatch-to-sample task also indicate that the limbic targets lesioned here may not be as exclusively involved in mnemonic information processing as suggested earlier.
Psychological Institute, University of Freiburg, F.R.G.
E
E
Irle
H J
HJ
Markowitsch
D000679:Amygdala / Q000033:anatomy & histology / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D006624:Hippocampus / Q000033:anatomy & histology / Q000502:physiology; D008032:Limbic System / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D012453:Saimiri; D013028:Space Perception / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology