Confocal mapping of cortical inputs onto identified pyramidal neurons

• Published in: Frontiers in bioscience Vol. 13; no. 13; pp. 6354 - 6373
• Main Authors: Ichinohe, Noritaka, Hyde, James, Matsushita, Atsuko, Ohta, Kazumi, Rockland, Kathleen S
• Format: Journal Article
• Language: English
• Published: United States 01.05.2008
• Subjects: Adenovirus; Animals; Brain - physiology; Brain Mapping; Cerebral Cortex - cytology; Cerebral Cortex - physiology; Cerebral Cortex - ultrastructure; Genes, Reporter; Green Fluorescent Proteins - analysis; Green Fluorescent Proteins - genetics; Macaca mulatta; Membrane Potentials - physiology; Microscopy, Confocal - methods; Neurons - cytology; Neurons - physiology; Neurons - ultrastructure; Pyramidal Cells - cytology; Pyramidal Cells - physiology; Pyramidal Cells - ultrastructure; Visual Cortex - cytology; Visual Cortex - physiology
• ISSN: 1093-9946; 1093-4715
• DOI: 10.2741/3159

Using a confocal microscopy protocol, we carried out a microcircuitry investigation of cortical connections in monkey temporal cortex. Inputs were labeled by BDA injections in posterior area TE, and potential postsynaptic pyramidal neuron targets were labeled with EGFP, by injection of retrogradely transported adenovirus. We scored the number and distribution of putative contacts onto dendritic compartments of neurons in different layers. Initial results show that about 50 percent of apical dendrites of layer (L.) 6 neurons receive contacts, as they ascend through L.4 (n=1 brain), but only 30-35 percent of those from L.5 neurons (n=2). Basal dendrites of L.3 neurons also receive few contacts in L.4. This supports the role of layer 4 as an interlaminar relay in association cortex. In addition, our results indicate spatial heterogeneity in the occurrence and number of contacts, possibly due to subtype specificity in target preference. The maximum number of contacts, for a L.2 neuron projecting from anterior to posterior TE, was 29. This approach seems a useful alternative or complement to electron microscopic analyses of long distance connectivity.