Mechanical slicing of frozen brain tissue: a reappraisal of catecholamine loss.

Catecholamine levels in mechanically sliced frozen bovine brain tissue were compared with those found in hand-cut, unfrozen tissue. Hemispheric content of catecholamines in small regions of cortex, caudate, nucleus accumbens, thalamus, and hippocampus in bovine brain was no different from that seen in the homologous area of the contralateral hemisphere, despite selective slicing of opposing hemispheres with the two techniques. Brodmann area 25 in human brain (previously suspected to be highly vulnerable to degradative loss of catecholamines by mechanical slicing) is shown to be a restricted area of dense catecholamine concentration when compared to surrounding cortical tissue. The usage of Brodmann area 25 for technique comparisons without precise control of cortical delineation is questioned.