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0:00
Welcome to this
Henry Stewart talk devoted
to the anatomical organization
of the basal ganglia.
My name is Andre Parent.
I am professor of
neuroscience at the University
Laval in Quebec City, Canada.
0:18
The aim of this presentation
is to provide an overall review
of the basal ganglia organization,
based on that I gathered
from the current literature,
as well as a result
of our own morphological studies
of the basal ganglia undertaken
in humans and non-human primates.
The talk is divided into
four distinct parts.
The first part concerns the overall
organization of the basal ganglia.
A special attention will be paid to
the dual basal ganglia model, which
is widely used to explain the
functional organization of the sets
of subcortical structures
in both health and disease.
The second part summarizes the
result of our own single-axon
tracing studies of the various
basal ganglia components in monkeys.
The third part is devoted to the
presence of dopaminergic neurons
within the primate striatum.
The last part of the
presentation reviews evidence
for the persistence of neurogenesis
in the striatum of adult primates.
1:35
This drawing of a coronal section
through to primate forebrain
provides an overall view of
the topographical organization
of the basal ganglia.
The basal ganglia are a set
of subcortical structures
that are reciprocally linked
with the cerebral cortex
via a relay in the thalamus.
The main axis of this
basal ganglia cortical loop
includes the following
sequentially-arranged elements.
First, the striatum, divided
into two main nuclei--
the caudate nucleus, labeled CD,
and the putamen, labeled PUT.
The striatum is the largest
and major integrative
component of the basal ganglia.
Second, the pallidum,
or globus pallidus,
comprising an external
segment, labeled GPe,
and an internal segment, labels GPi.
The latter nucleus is a major output
structure of the basal ganglia.
Third, the substantia nigra, divided
into a pars compacta, labeled SNc,
and a pars reticulata, labeled SNr.
The pars reticulata of
the substantia nigra
is another major output
structure of the basal ganglia.
Finally, the ventral tier thalamic
nuclei, labeled Th in this drawing,
whose premotor neurons convey the
information that has been processed
through the basal ganglia back
through the cerebral cortex.
Various control or
modulating structure
also plays a crucial
role in the functional
organization of the basal ganglia.
Among those are the
subthalamic nucleus,
labeled STN, which is reciprocally
linked with the external pallidum
And the substantia
nigra pars compacta,
labeled SNc, whose
dopaminergic neurons
project massively to the striatum.
Various other brain
stem and thalamic nuclei
also exert a significant
modulating influence
upon the basal ganglia components.
But for the sake of
clarity, these structures
have not been included
in this drawing.
