Local synaptic connections of basal forebrain neurons

Single, biocytin filled neurons in combination with immunocytochemistry and retrograde tracing as well as material with traditional double-immunolabel ing were used at the light and electron microscopic levels to study the neu ral circuitry within the basal forebrain. Cholinergic neurons projecting to the frontal cortex exhibited extensive local collaterals terminating on no n-cholinergic, (possible GABAergic) neurons within the basal forebrain. Ela borate axon arbors confined to the basal forebrain region also originated f rom NPY, somatostatin and other non-cholinergic interneurons. It is propose d that putative interneurons together with local collaterals from projectio n neurons contribute to regional integrative processing in the basal forebr ain that may participate in more selective functions, such as attention and cortical plasticity. (C) 2000 Elsevier Science B.V. All rights reserved.