Multiple studies have explored the relationship between MRI-based
volumetric measurements of the hippocampus and amygdala, the degree of
volumetric asymmetry of these structures, and symptom manifestation.
However, considerable variability exists with regard to the reported
volumetric values of these structures. The present study employed
meta-analytic procedures to provide a systematic analysis of the normal
population parameters of hippocampal and amygdala volumetric asymmetry
as well as the absolute intrahemispheric volumes of these structures in
normal adults. A literature review of studies published between 1990
and 2002 resulted in a representative sample of 82 studies (N
= 3,564 participants) providing volumetric information of the
hippocampus and 51 studies (N = 2,000 participants) providing
volumetric information of the amygdala. Results revealed that both the
hippocampus and the amygdala are reliably asymmetrical structures in
normal adults, with larger right hippocampal (D = 0.21,
p < .001) and right amygdala (D = 0.09, p
< .01) volumes. Additional analyses indicated that differences in
MRI magnet field strength and slice thickness values might
differentially contribute to volumetric asymmetry estimates. These
results expand on previous volumetric normative studies and may be
relevant to investigators studying the clinical correlates of
hippocampal and amygdala volumes. (JINS, 2004, 10,
664–678.)