Basal Ganglia Prof K Sivapalan Basal Ganglia 10242021

Basal Ganglia Prof. K. Sivapalan

Basal Ganglia. 10/24/2021 Basal ganglia 2

Basal Ganglia. 10/24/2021 Basal ganglia 3

Connections. • Main input- corticostriate projection – from all parts of cortex. • Centromedian nucleus of the thalamus also projects to striatum. • Principal output- from the internal segment of globus palidus via thalamic fasciculus to ventral lateral, ventral anterior, and centromedian nuclei of the thalamus. • Thalamic nuclei project to Motor cortex and premotor cortex. • Substantia nigra also projects to thalamus. 10/24/2021 Basal ganglia 4

Connections. 10/24/2021 Basal ganglia 5

Functions • Cells in the basal ganglia discharge before movement begin. • It is probably planning and programming of movements or involved in the process by which an abstract thought is converted into voluntary movement. 10/24/2021 Basal ganglia 6

Diseases of Basal ganglia Hyperkinetic disorders. Chorea- rapid involuntary dancing movements. Athetosis- continuous slow writhing movements Ballism- flailing, intense and violent. Hypokinetic disorders. Akinesia – difficulty in movement and decreased voluntary movement. • Bradykinesia. - slowness of movement. • • • 10/24/2021 Basal ganglia 7

Huntington’s disease Huntington’s Chorea Hereditary disorder , symptoms at 30 -40 years. Flicking movements in individual joints. Progressive distortional movements of the entire body. • Also severe dementia develops. • Loss of GABA secreting cells in caudate nucleus. • • 10/24/2021 Basal ganglia 8

Parkinson’s disease. • Paralysis agitans. • Destruction of pars compacta of the substantia nigra. • Rigidity • Resting tremor. • Akinesia. 10/24/2021 Basal ganglia 9

Site of Lesion and Transmitters Condition Site Neurotransmitter Parkinson’s disease Putamen Dopamine ↓ 90% Noradrenaline ↓ 60 % 5 HT ↓ 60 % Substance nigra Dopamine ↓ 90% GABA ↓↓ Cerebral Cortex GABA ↓↓ Huntington’s disease Corpus Striatum Acetylcholine ↓↓ GABA ↓↓ Hemiballismus Subthalamic nucleus Infarct 10/24/2021 Basal ganglia 10