AMINES AND PEPTIDES IN THE BRAIN OF THE AMERICAN LOBSTER - IMMUNOCYTOCHEMICAL LOCALIZATION PATTERNS AND IMPLICATIONS FOR BRAIN-FUNCTION

The distributions of serotonin- (5HT-), substance P- (SP-), small card ioactive peptide(b-) (SCPb-), and histamine- (HA-) like immunoreactivi ties were examined in the adult lobster supraesophageal ganglion. Vibr atome sections were labeled using avidin-biotin-peroxidase immunocytoc hemical methods. The localization patterns for each substance were ass essed in 21 regions within the median protocerebrum deutocerebrum and tritocerebrum. Each immunoreactivity has a unique distribution within the brain; however, most regions are immunoreactive for more than one neurotransmitter. Of particular interest are SP-immunoreactive protoce rebral neurons that contact olfactory projection neurons and appear ho mologous to those found in other crustaceans. Regional differences in immunolabeling within the deutocerebral olfactory and accessory lobes suggest that specific areas within individual olfactory lobe glomeruli serve distinct functions in olfactory processing, and that subpopulat ions of accessory lobe glomeruli are innervated by different groups Of neurons. This detailed comparison of the labeling patterns also has a llowed us to define the anatomical connectivity between several cell b ody clusters, fiber tracts, and neuropil areas in the lobster brain.