1. Corpus Striatum: putamen, globus pallidus, & caudate nuclei
2. basil ganglia: this term has been used to describe this area
of the brain.
A. components:
a. caudate nucleus
b. putamen
c. globus pallidus (paleostriatum or pallidum)
d. nucleus accumbens (frequently considered part
of the limbic system)
e. substantia nigra (frequently not included as
basal ganglia)
f. subthalamic nuclei: (frequently not included
as basal ganglia)
g. claustrum (usually included but not by Kingsley)
h. some put the amygdala in this group
3. lentiform nucleus: putamen & globus pallidus
A. grouping these structures is probably not appropriate.
P 249 Kiernan
4. external capsule: white matter lateral to the lentiform nucleus
5. claustrum: gray matter immediately lateral to the putamen
6. extreme capsule: white matter that separates the claustrum from the insula
7. internal capsule: runs between the caudate nucleus & putamen
II. neostriatum (striatum): includes the caudate, putamen, and nucleus
accumbens (NA)
1. this is the newest part of the basal ganglia (from telencephalon)
2. Caudate nucleus: p. 249-250
A. parts include the head & tail (tale terminates
at the amygdala)
3. the most ventral striatum is called the nucleus accumbens (NA)
4. afferents to the striatum
A. cerebral cortex (corticostriate fibers)
B. thalamus: (thalamostriate) fibers originate in intralaminar
nuclei
C. substantia nigra (nigrostriate) from the pars compacta (midbrain)
D. amygdala: fiber from here synapse in the NA & caudate
(via stria
terminalis)
5. efferents from the striatum (cells release GABA primarily)
A. globus pallidus (striopallidal fibers)
B. substantia nigra (strionigral fibers) axons end in both parts
of the
substantia Nigra (pars compacta
& pars reticulata)
III. pallidum (paleostriatum): is the globus pallidus
1. situated between the putamen & the internal capsule
2. it can be divided into 2 divisions
A. lateral (GPl)
B. medial (GPm)
a. functionally identical to substantia nigra
pars reticulata
3. afferents to the globus pallidus
A. striatum
B. substantia nigra
C. subthalamic nucleus
4. efferents from the globus pallidus (cells release GABA primarily)
A. thalamus
B. habenular nuclei: part of the diencephalon (posterior thalamus)
C. pallidofugal fibers also project to the superior colliculus
(midbrain)
D. brainstem reticular formation (p. 183 lower)
E. subthalamic nucleus
IV. substantia nigra (SN): just dorsal to BP
1. two parts are described in our text
A. pars compacta:
a. neurons here produce lots of dopamine
b. efferent axons travel to the
?striatum (forebrain) via the nigrostriatal
pathway
?amygala
?prefrontal cortex
B. pars reticulata: this is probably a detached segment of the
globus
pallidus
a. neurons probably make & release GABA
b. efferent axons project to the
?thalamus
?S. colliculus
V. Pyramdal & extrapyramidal systems
1. Pyramidal system: an old fashioned term referring to the
corticospinal &
corticobulbar tracts
2. extrapyramidal system: movement areas outside the pyramidal
system
A. including the reticulospinal, vestibulospinal,
& basal ganglia
Dyskinesia & Disease of the Basal Ganglia:
I. Dyskinesia involves a loss of voluntary control of movements with
no
paralysis, paresis, or apraxia.
II. there are two categories of dyskinesia
1. hyperkinesia: unplanned spontaneous movements
A. choreiform movements: brisk jerky movements involving
several muscle
groups.
B. athetosis: slow writhing movements usually of the hands,
face, or tongue
a. side effect of antipsychotic medications
(extrapyramidal side effects)
b. seen in tardive dyskinesia
C. dystonic movements: prolonged contractions of the neck,
trunk, or limbs
that lead to abnormal postures
& twisting
a. idiopathic torsion dystonia:
b. spasmodic torticollis:
D. myoclonus: sudden spasms of the muscle usually lifting
& flailing the
arms
a. seen in degenerating brain diseases
e.g., spongiform encephalopathies
b. nocturnal myoclonus:
c. ballism: irregular flinging movements
of the limbs
E. tics: stereotyped (repetitive) involuntary movements
(often are twitches)
a. seen in Gilles de al Tourette syndrome
F. tremor: rhythmical alternating movements that can effect
any part of the
body
G. akathisia: restless agitation (can’t sit still)
2. hypokinetic dyskinesia:
A. bradykinesia: a poverty or slowness of movements
III. diseases effecting the basal ganglia:
1. Parkinson's disease due primarily to degeneration of
dopamine neurons
in the substantia nigra pars compacta
A. a loss of pigmented cells in other brain areas may occur
(e.g. locus
Ceruleus & dorsal motor nucleus
of the vagus)
B. This disease results in
a. bradykinesia:
C. This cause of abnormal dopamine cell loss in the substantia
nigra is still a
mystery
a. toxins, faulty metabolism, or infections have
been implicated
->encephalitis lethargica:
D. treatment usually involves some sort of DA agonist
a. L-dopa is used to treat Parkinson's
b. deprenyl (MAO inhibitor) looks promising.
E. surgical procedure are also used for treatment
a. brain lesions: destroying part of the globus
pallidus
2. Huntington’s disease
A. a genetic disorder with symptoms appearing in mid life
B. it alters the brain in the following ways
a. degeneration of the caudate N and putamen mostly
b. some cells in the cortex also die
C. This produces uncontrollable movements (choreiform)
a. early in the disease process they may seem
restless or fidgety
b. eventually patients are in constant motion
& finally athetosis or dystonia
D. progressive mental deterioration also occurs
E. changes in personality often occur
3. cerebral palsy: effects this area of the brain
A. movement disorder due to brain injury occurring near or during
birth
4. Wilson’s disease:
A. caused by a genetic error in copper metabolism
B. symptoms occur between ages 10 & 25 & include the
following
5. tardive dyskinesia: permanent brain damage due to antipsychotic meds.
6. abulia: a loss of will power & initiative
A. seen in people with caudate nucleus lesions