functions of basal ganglia and detail structure is discussed in the slides. Cognitive process of thinking is discussed.

1. BASAL GANGLIA
DR. PRIYANKA SRIVASTAVA

2. INTRODUCTION
 Basal ganglia - Another accessory
motor system.
 Function- in association with the
cerebral cortex & corticospinal motor
control system.
 Input- From the Cerebral Cortex.
 Output- Back to the Cortex.

3. BASAL GANGLIA
Collection of masses of gray matter
situated within each cerebral hemisphere.
 They are paired & located between
thalamus and white matter.
 Consist of 5 pairs of nuclei: These are
 Caudate nucleus
 Putamen
 Globus pallidus
 Substantia nigra
 Subthalamic nucleus.

4. Anatomy of Basal Ganglia

8. Neuronal Circuitry of Basal
Ganglia

12. PUTAMEN CIRCUIT
 Inputs -mainly from those parts of
brain adjacent to primary motor cortex.
 Output- mainly go back to the Primary
motor cortex or closely associated
premotor & supplementary cortex.

13. Abnormal Functions in Putamen
Circuit
 Athetosis – spontaneous & writhing
movements of a hand, an arm, the
neck or the face. It is due to lesion in
Globus pallidus.
 Hemiballismus- lesion in the
Subthalamus leads to sudden flailing
movements of an entire limb.

14. Abnormal Functions in Putamen
Circuit
 Chorea – Multiple small lesions in the
putamen leads to flicking movements
in the hands, face, & other parts of the
body called Chorea.
 Parkinson’s Disease- lesions of
Substantia nigra leads to a common &
extremely severe disease of rigidity,
akinesia & tremors.

17. Caudate Circuit- Cognitive
Control
 Cognition – Thinking process of the
brain using sensory input to the brain
plus information already stored in
memory.
 Most of our motor actions occurs as a
consequence of thoughts generated in
the mind, a process called cognitive
control of motor activity.
 Caudate nucleus plays a major role in
this cognitive control of motor activity.

18. Caudate Circuit- Cognitive
Control
 The neural connections b/w caudate
nucleus & corticospinal motor control
system are different from those of
putamen circuit.
 As Caudate nucleus extends into all
the lobes of the cerebrum, beginning
anteriorly in the frontal lobes, then
passing posteriorly through the
parietal & occipital lobes & finally
curving again like the letter “C” into the
Temporal lobes.

19. Caudate Circuit- Cognitive
Control
 Inputs- Associated areas of the
cerebral cortex overlying the caudate
nucleus, areas that integrate diff types
of sensory & motor information into
usable thought patterns.
 After the signals pass from the
cerebral cortex to the caudate
nucleus, they are next transmitted to
the internal Globus pallidus, then to
the relay nuclei of the VA & VL
thalamus.

20. Caudate Circuit- Cognitive
Control
 Output- And from thalamus back to the
Prefrontal, Premotor & supplementary
motor areas of the cerebral cortex but
with none of the signals passing directly
to the primary motor cortex.
 Instead the returning signals go to those
accessory motor regions in the premotor
& supp. motor areas that are concerned
with putting together sequential patterns
of movt. Lasting 5 or more seconds
instead of exciting individual muscle
movt. Eg. Person seeing a lion

21. Functions of Basal Ganglia
 2 imp. capability of the brain in
controlling movements are
 1) To determine how rapidly the movt. is
to be performed. i.e timing of
movement.
 2) To control how large the movt. will
be? Scaling of movement.
 For ex: writing a letter “a”.

22. Functions of Basal Ganglia
 In patients with severe lesions of basal
ganglia these timing & scaling
functions are poor.
 In this also basal ganglia works
inconsistent with the cerebral cortex.
 Posterior parietal cortex is the locus of
spatial coordinates for motor control of
all parts of the body.
 Lesion of this area leads to Agnosia.
 Inability to perceive objects through
normally functioning sensory

23. Functions of Basal Ganglia
 Personal neglect syndrome.
 Caudate circuit of the basal ganglia
systems functions mainly with
association areas of the cerebral
cortex such as the posterior parietal
cortex, so timing and scaling of movt.
are functions of this caudate
cognitive motor control circuit.

24. Functions of Specific Neurotransmitter substances in
the Basal Ganglia System

25. Functions of Specific
Neurotransmitter substances
 1)Dopamine pathways from the
Substantia nigra to the Caudate nucleus
& Putamen.
 2)Gamma aminobutyric acid(GABA)
pathways from the caudate nucleus &
putamen to Globus pallidus & Substantia
nigra.
 3)Acetylcholine pathway from the Cortex
to the Caudate nu & Putamen.
 4)Multiple general pathways from the
brain stem that secrete NE, Serotonin,

26. Functions of Specific
Neurotransmitter
 4)Multiple general pathways from the
brain stem that secrete NE, Serotonin,
Enkephalin etc.
 5) Glutamate pathways- That provide
most of the Excitatory signals that
balances the large inhibitory signals.
 GABA- Inhibitory negative feedback
loops.
 Dopamine- Inhibitory neurotransmitter
in most parts of the brain.

28. PARKINSON’S DISEASE

29. PARKINSON’S DISEASE
 It is a clinical syndrome resulting from
damage to the Basal Ganglia.
 Paralysis agitans results from
widespread destruction of that portion
of Substantia nigra(the pars
compacta) that sends dopamine-
secreting nerve fibers to the caudate
nucleus & putamen & is characterized
by rigidity, tremors & akinesia.