Basal ganglia

1. B A S A L G A N G L I A
Presenter - Dr.G.Madhuri
1st yr.Pg
Chairperson - Dr.S.Nagaraju
Professor
Dept of psychiatry
MIMS

2. SCHEME OF PRESENTATION
1. Structure & Nuclei of basal ganglia
2. Connections of basal ganglia
3. Different types of pathways
4. Functions of basal ganglia
5. Disorders of basal ganglia
6. Movement disorders of basal ganglia

3. BASAL GANGLIA
 These are a basically set of deep nuclei within or around the basal part
of the brain.
 These are involved in motor control, action, selection & learning
processes.

4. Basal ganglia includes structures-;
1. Caudate nucleus
2. Putamen
3. Globus pallidus
4. Subthalamic nuclei
5. Substantia nigra

7. • Neo Striatum – Caudate Nucleus + Putamen
• Paleo Striatum – Globus palidii(interna + externa)
• Corpus Striatum – Caudate Nucleus + Putamen + Globus Pallidus
• Lentiform Nucleus – Putamen + Globus Pallidus

8. 1. CAUDATE NUCLEUS
• Telencephalic in origin.
• C-shaped structure
• Divided into three parts – Head, Body and Tail.
• Associated with Contour of Lateral Ventricles.
• Head is continuous with the Putamen.
• Tail terminates in the Amygdala of Temporal lobe.

9. LENTIFORM NUCLEUS
- Biconvex lens shape like.
- Triangular in both coronal & horizontal sections.
- Divided into 2 parts by extrenal lamina of white matter.
- It contains- putamen + globus pallidus

10. PUTAMEN
• Telencephalic in origin.
• Bounded laterally by the External Capsule.
• Medially by Globus Pallidus.
• Separated from the Caudate by theAnterior limb of the Internal Capsule.

12. GLOBUS PALLIDUS
• Diencephalic in origin
• Latin-“Pale Globe” also known as Paleostriatum
• Inner component of the Lentiform Nucleus
• Cone like structure with top directed medially
• Bounded medially by posterior limb of Internal Capsule.
• Laterally by Putamen.
• Divided into external and internal segments by Medial Mamillary Lamina.

14. SUBTHALAMIC NUCLEI
• Diencephalic in origin.
• It lies dorsomedial to posterior limb of internal capsule.
• It is situated dorsal to substantia nigra.

15. SUBSTANTIA NIGRA
• Mesencephalic in origin
• Present in midbrain and consists of two components.
• Pars Compacta
• Pars Reticulata

17. PARS COMPACTA
• Dorsal Part
• Rich in cells
• Rich in Neuromelanin (so
Pigmented)
• Neurotransmitter-Dopamine
• Calbindin +ve
• Sends projections to areas of
Striatum dominated by limbic related
structures and association regions of
the Cerebral Cortex
• Associated with Schizophrenia
PARS RETICULATA
• Ventral part
• Sparse number of cells
• Neurotransmitter- GABA
• Calbindin –ve
• Sends projections to
sensorimotor regions of the
striatum
• May be associated with
Parkinsons Disease

18. CONNECTIONS
• Main input = to caudate + putamen
• Main output = globus pallidus

19. Inputs/ Afferents to basal ganglia
• Striatum is the major recipient of inputs to the basal
ganglia.
• Three major afferent pathways are known to
terminate in the striatum.
1. Corticostriatal- glutaminergic
2. Nigrostriatal - dopaminergic
3. Thalamostriatal - from centromedian nucleus

20. Corticostriatal pathway
• Originates from all regions of Neocortex
• Primarily from Pyramidal cells of layers V and VI
• Uses Excitatory neurotransmitter – Glutamate
• Afferents from:
Sensorimotor cortex
Association Regions
Putamen
Caudate Nucleus
• Afferents from the Limbic Cortex:
Hippocampus
Terminate in the Ventral Striatum
Amygdala

21. • Nigrostriatal pathway:
• Arises from Substantia Nigra (Pars Compacta)
• Neurotransmitter-Dopamine
• Thalamostriatal Pathway:
• Originates in the Thalamus
• The thalamic nuclei providing the projections are the Intralaminar Nuclei,
Particularly the Central Median Nucles.

22. THALAMOSTRIATAL NIGROSTRIATAL
CORTICOSRIATAL

23. EFFERENTS FROM BASAL GANGLIA
• The GPi is the source of much of the input to the Basal Ganglia
• This Segment of the Globus Pallidus provides projection to the Ventrolateral
(VL) and Ventroanterior (VA) nuclei of the Thalamus and the Central Median
Nucleus.
• The Pars Reticulata of substantia nigra also provides projections to VL & VA
• These projections of VL & VAproject to Premotor & Prefrontal cortices.
• Projections of the Premotor and Prefrontal cortices project to primary motor
cortex, so basal ganglia are able to influence indirectly the output of primary
motor cortex.

27. Functions of basal ganglia
1. Control of voluntary motor activity.
2. Control of reflex muscular activity
3. Control of muscle tone
4. Role in arousal mechanism.

29. • Control of reflex muscular activity
- Has inhibitory effects on spinal reflexes.
- Maintains posture
• Control of muscle tone
- Through reticular formation- in BG lesion- rigidity occurs.
• Role in arousal mechanism
- Through its connections with reticular formation
• Role in emotions & learning

30. DISORDERS OF BASAL GANGLIA
1. PARKINSONS DISEASE
2. HUNTINGTONS DISEASE
3. WILSONS DISEASE
4. PROGRESSIVE SUPRANUCLEAR PALSY

31. PARKINSONS DISEASE
• A neurodegenerative disease associated with loss of dopaminergic neurons in
the substantia Nigra (Pars Compacta).
• In 1817,James Parkinson described paralysis agitans in his“Essay on the Shaking
Palsy”.
• Parkinson’s disease affects movement,producing motor symptoms,nonmotor
symptoms,which includeAutonomic dysfunction,neuropsychiatric problems
(mood,cognition,behaviour or thought alterations),sensory and sleep difficulties
are also common

35. PARKINSON'S DISEASE IS ALSO ASSOCIATED WITH
COGNITIVE AND PSYCHIATRIC MANIFESTATIONS
• Depression
• Apathy
• Anxiety
• Psychosis

36. HUNTINGTONS DISEASE
• Huntington’s disease (formerly Huntington's chorea) is an autosomal dominant
neurodegenerative disorder characterized by middle onset,a relentlessly
progressive course and a combination of motor,psychiatric and cognitive
symptoms.
• First described by George Huntington in 1872.
• The disease is caused by a CAG repeat expansion mutation in the Huntington
gene on chromosome 4.

37. Primary involuntary movement abnormality:
• Chorea or Choreoathetosis
Associated involuntary movement abnormality:
• Visual tracking
• Fine motor movements
• Gait disturbances
Psychiatric manifestations:
• Higher rates of suicide
• Depression (30-40% Major Depression; 10-20% less severe form of depression)
• Mania (10% cases)
• Personality change (50% cases)

39. WILSONS DISEASE
• Autosomal recessive disorder in which mutations in the gene ATP7B result in
abnormal copper accumulation in the liver, Basal Ganglia and other tissues.
• Neuropsychiatric pathophysiology:
When copper deposits in the basal ganglia specifically in the putamen and globus
pallidus (lenticular nucleus), there is cell death.

40. • Personality changes
• Depression
• Suicidality
• Anxiety disorders
• Psychotic disorders
• Neurological Findings • Psychiatric Manifestations

42. SUPRANUCLEAR PALSY
Neurological findings
• Symmetric bradykinesia
• Axial rigidity
• Postural instability with falls
• Dysarthria
• Dysphagia
• Supranuclear gaze palsy (paralysis of
downward vertical gaze)
Psychiatric symptoms
• Subcortical dementia with
Bradyphrenia
• Memory deficits,Irritability
• Predominant frontal lobe dysfunction
with Executive andAttention deficits
• Frontal behavioral disturbances of
Apathy and Disinhibition
• Sleep disturbances,Depression
• Emotional lability including
pathological Laughter & Crying

45. ATHETOSIS
• Slow,writhing,involuntary
movements with a propensity to
affect arms and hands.

46. HEMIBALLSIMUS
• A violent form of chorea that
comprises wild,flinging,large
amplitude movements on one side
of the body.

47. CHOREA
• Rapid,semi-purposeful,graceful,dance
like non-patterned involuntary
movements involving distal or proximal
muscle groups.
• When movements are of large
amplitude and forceful,the disorder is
called ballism

48. DYSTONIA
• Sustained or Repetitive
involuntary muscle contractions
frequently causing twisting
movements with abnormal
postures.

49. TREMORS
• Regular oscillating movement about a joint due to synchronous contraction of agonist and antagonist
muscles.
1. Rest Tremors:
• Movement occurs in a relaxed supported extremity
• Reduced by ambulation
• Distinctive in parkinsonism
2. Postural Tremors:
• Sustained Posture Elicit Tremor (e.g: outstretched hand)
• A course irregular rapid postural tremor is often seen in metabolic encephalopathy.
3. Intention Tremor:
• Active limb oscillates more prominently when reaching target.
(eg: Patient trying to touch the examiner’s finger)