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BASAL GANGLIA
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Basal ganglia 2010

May 07, 2015

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Page 1: Basal ganglia 2010

BASAL GANGLIA

Page 2: Basal ganglia 2010

SUBDIVISION OF BG

A. Neostriatum or Striatum

PutamenCaudate nucleus

B. Pallio striatum or Pallidum

Globus pallidus

C. Lentiform nucleusPutamenGlobus Pallidus

D. ArchistiatumAmygdela

E. Substantia nigraF. Subthalamic nucleus

Page 3: Basal ganglia 2010

FUNCTIONAL ORGANIZATION OF BG

Page 4: Basal ganglia 2010

MOTOR COMPONENT OF BASAL GANGLIA

Page 6: Basal ganglia 2010

BASAL NUCLEI

Page 7: Basal ganglia 2010

GROSS ANATOMY OF BG

Page 8: Basal ganglia 2010

INTERNAL CAPSULE & BG

Page 9: Basal ganglia 2010

BASAL FOREBRAIN

Page 10: Basal ganglia 2010

STIATUM

Page 11: Basal ganglia 2010

SUBTHALAMIC NUCLEUS

Page 12: Basal ganglia 2010

GLOBUS PALLIDUS (INTERNAL)

Page 13: Basal ganglia 2010

SUBSTANTIA NIGRA PARS RETICULATA

Page 14: Basal ganglia 2010

GLOBUS PALLIDUS (EXTERNUS)

Page 15: Basal ganglia 2010

SUBSTANTIA NIGRA PARS COMPACTA

Page 16: Basal ganglia 2010

STRIATAL PARALLEL PATHWAY

Page 17: Basal ganglia 2010

EFFERENT OF BG

Page 18: Basal ganglia 2010

OUTPUT OF THE BASAL GANGLIA

Page 19: Basal ganglia 2010

OUTPUTS OF THE BASAL GANGLIA AND THEIR TRAJECTORIES

Page 20: Basal ganglia 2010

BG EFFERNTS

Page 21: Basal ganglia 2010

NERUONS AND CIRCUITS OF BG

Page 23: Basal ganglia 2010

CONNECTIONS OF THE NEOSTRIATUM WITH THE SUBSTANTIA NIGRA

Page 24: Basal ganglia 2010

CORTICAL LOOP

Cortex: 4,6,temporo, parietal and occipital glutamate

Striatum spiky GABA Pallidum medial

GABA Thalamus VL, VA

Page 25: Basal ganglia 2010

BG: SUBCORTICAL LOOPS

In the case of all sub-cortical loops the position of the thalamic relay is on the input side of the loop

Red – Excitatory Blue - Inhibitory

Page 26: Basal ganglia 2010

INTERNAL CONNECTIONS OF THE BASAL GANGLIA: DIRECT PATHWAY

Page 27: Basal ganglia 2010

INDIRECT PATHWAYS

Page 28: Basal ganglia 2010

PROJECTIONS FROM THE BASAL GANGLIA TO OTHER BRAIN REGIONS

Page 30: Basal ganglia 2010
Page 31: Basal ganglia 2010

FUNCTION OF BG

Voluntary movement Initiation of movement Control of ramp movement Change from one pattern to other Programming and correcting movement while in

progress (thalamocortical circuts) Postural control

Righting reflex Automatic associated movement (walking)

Control of muscle tone Reticulospinal Vestibulospinal

Page 32: Basal ganglia 2010

ABLATION STUDY Unilateral lesion minimal effect Denny Brown – Bilateral lesion -> Akinesia + Flexion

dystonia Brook – Cooling of GP -> Contralateral cocontraction of

antagoniastic muscle -> Flexion, alternate and amplitude of movement

Bilateral striatal ablation -> Overactive, does not respond to visual cue – walk to wall

Bilateral pallidal ablation -> Hypoactive akinetic Human sterotactic Gpi lesion -> tremor >rigidity Subthalamic Nucleus ablation -> Hemibalismus Bilateral CN ablation -> immobile animal VL thalamic cooling -> Ia discharge to stretch reflex -

> rigidity by y tone

Page 33: Basal ganglia 2010

STIMULATION STUDIES

CN stimulation -> head and body turn to opposite site, circling movement, or mild hypertonia, late tremor, changes tonic to clonic phase of epilepsy

Neostriatal stimulation -> arrest of motion in progress

Page 34: Basal ganglia 2010

MICROELECTRODE RECORDING Activity seen during initiation of internally generated

movement but not to stimulus triggered movement Activity seen during co-contraction of agonist (stimulus

triggered thus control amplitude and velocity of movement

Preparation of motor act or programming as MC and SMA React

Spontaneous movement of individual body part Alternating movement Visually and kinesthetically triggered movement Postural adjustment to body tilt Rapid ballistic movement Slow ramp movement Isometric muscle contraction

SNc – tonic discharge -> postural control SNr - phasic discharge change with limb movement

Page 35: Basal ganglia 2010

Cortex

DISCHARGE OF MOTOR CIRCUIT

No spontaneous discharge, only during limb movement

increased phasic activity

High spontaneous discharge, inhibit tonicaly thalamus

Phasic reduction of activity during movement due to disinhibition by striatum

Phasic activity during movement

Striatum

GPi SNr

Thalamus

1

2

3

4

5

Page 36: Basal ganglia 2010

A CONCEPTUAL MODEL OF ACTION SELECTION BY THE BASAL GANGLIA

Page 37: Basal ganglia 2010

PROPOSED MECHANISMS FOR SERIAL SELECTION WITHIN THE BASAL GANGLIA

Page 38: Basal ganglia 2010

BG AND EYE MOVEMENT

Page 41: Basal ganglia 2010

POSSIBLE ROLE OF INTRINSIC CIRCUITS

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THE END