Background
Two types of dendrites present on pyramidal cells are apical and basal dendrites. Apical dendrites can be divided into two categories: distal and proximal. The longer distal apical dendrites project from the pyramidal cell body (soma) opposite from the axon. Distal apical dendrites form non-local synapses. Shorter proximal apical dendrites project radially to local pyramidal cells and interneurons. Pyramidal neurons segregate their inputs using proximal and apical dendrites.
Apical dendrites are studied in many ways. In cellular analysis, the electrical properties of the dendrite are studied using stimulus responses. A single surface shock of the cerebral cortex induces a 10-20msec negative potential, a manifestation of the summed excitatory post-synaptic potentials (EPSPs) evoked in the distal portions of the apical dendrite. This has been called the Dendritic Potential (DP). This is identical with Adrian’s Superficial Response in direct cortical responses. At higher intensities the DP is followed by slow positive waves (Adrian’s Deep Response) or by a prolonged negative wave lasting for more than 200msec (Chang’s second component). The highest amplitude of DPs is found on the cortical surface, with the polarity shifted from negative to positive within the superficial layer.
Read more about this topic: Apical Dendrite
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