Emergence of stereotypies in juvenile monkeys (Macaca mulatta) with neonatal amygdala or hippocampus lesions.
The emergence of stereotypies was examined in juvenile rhesus monkeys (Macaca mulatta) who, at 2 weeks of postnatal age, received selective bilateral ibotenic acid lesions of the amygdala (N = 8) or hippocampus (N = 8). The lesion groups were compared to age-matched control subjects that received a sham surgical procedure (N = 8). All subjects were maternally reared for the first 6 months and provided access to social groups throughout development. Pronounced stereotypies were not observed in any of the experimental groups during the first year of life. However, between 1 to 2 years of age, both amygdala- and hippocampus-lesioned subjects began to exhibit stereotypies. When observed as juveniles, both amygdala- and hippocampus-lesioned subjects consistently produced more stereotypies than the control subjects in a variety of contexts. More interesting, neonatal lesions of either the amygdala or hippocampus resulted in unique repertoires of repetitive behaviors. Amygdala-lesioned subjects exhibited more self-directed stereotypies and the hippocampus-lesioned subjects displayed more head-twisting. We discuss these results in relation to the neurobiological basis of repetitive stereotypies in neurodevelopmental disorders, such as autism.
Bauman
M D
MD
Department of Psychiatry and Behavioral Sciences, Center for Neuroscience, The M.I.N.D. Institute, University of California at Davis, CA 95817, USA. mdbauman@ucdavis.edu
Toscano
J E
JE
Babineau
B A
BA
Mason
W A
WA
Amaral
D G
DG
D000367:Age Factors; D000679:Amygdala / Q000293:injuries* / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001835:Body Weight; D005260:Female; D006624:Hippocampus / Q000293:injuries* / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D013239:Stereotyped Behavior / Q000502:physiology*