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ANATOMY
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>Transmitter-spec...
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>General
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1.12.1. General.
The generally held view is that synaptic input to the cell bodies and
proximal dendrites of BFC neurons is sparse, but it increases on more distal
dendritic segments (Ingham et al., l985; Armstrong, l986; Dinopoulos et al.,
l986; Bialowas and Frotscher, l987; Ingham et al., l988; Martinez-Murillo et al.,
l990; Milner, l991. * (Fig.1.12.1-1.). A more
systematic analysis, however, suggests that the synaptic density on the cell
body shows considerable regional variation. Cholinergic cell bodies in the
internal capsule or in the area of the globus pallidus are surrounded by
myelinated fibers, and the majority of corticopetal cholinergic cell bodies in
these areas receive synaptic boutons only extremely rarely. On the other hand,
cholinergic cells in the ventral pallidum, near the substriatal gray (Fig.1.12.1-2}) receive a large number of
synaptic input to the perikaryon. (Fig.1.12.1-
2.).
* (Fig.1.12.1-3 shows several
examples of synapses on identified cholinergic neurons. As suggested in the
schematic drawing of * (Fig.1.12.1-3.A),
various inhibitory synapses appear to show a preferential distribution on the cell
body or proximal part of the dendrite. These terminals are likely to originate
mainly from local interneurons. On the other hand, excitatory inputs from more
distant areas apparently concentrate on more distal dendritic segments. This
afferent "synaptic topography" (Smith and Bolam, l990) based on the available
data may represent a first level of integration of afferent information. Another
level of interaction between inputs may be represented through local
GABAergic and peptidergic interneurons (Fig.1.16-
1).
