Allows for sustain acmons or inimamon of acmon

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Unformatted text preview: cles, etc. → (hyperkineEc state) •  Putamen GPi, SNr –  Reduce output from GPi (GABA) –  Thalamus disinhibited –  Allows movement (cortex) •  MalfuncMon Parkinson’s Disease –  Bradykinesia Indirect Pathway •  Cortex (sEmulates) → Striatum (inhibits) → GPe (less inhibiEon of STN) → STN (sEmulates) → "SNr ­ GPi" complex (inhibits) → Thalamus (is sEmulaEng less) → Cortex (is sEmulaEng less) → Muscles, etc. → (hypokineEc state) •  Putamen ( ­) GPe ( ­) STN (+) Gpi –  Net output from GPi GABA –  Inhibits thalamus –  Inhibits movement (cortex) •  MalfuncMon HunMngton’s Disease –  Chorea –  . Circuitry of basal ganglia Direct path: striatum GPi (internal) thalamus cortex Indirect path: striatum GPe (external) STN GPi thalamus cortex Circuitry of basal ganglia Direct path:  ­ Leads to less inhibiMon of the thalamus, i.e. striatum inhibits GPi which in turn inhibits its normal (inhibitory) acMon on the thalamus, thus leading to greater excitaMon from the thalamus to the cortex.  ­ Allows for sustain acMons or iniMaMon of acMon Indirect path:  ­ Excites the GPi thereby increasing its inhibiMon of the thalamus  ­ Suppresses unwanted movements. Parkinson disease: Basal ganglia circuitry Abnormal funcMoning Analogy Parkinson’s Disease Meri Gukasyan Parkinson’s disease is a debilitaMng disease of the motor neurons, specifically dopamine producing cells in the substanMa nigra. Dopamine is a chemical messenger that carries signals to specific parts of the brain that control movement iniMaMon and coordinaMon. The reasons for Parkinson’s disease are currently unknown and there is no cure. Parkinson’s •  Parkinson’s disease (PD) involves muscle rigidity, resMng tremor, slow movements –  –  Parkinson’s results from damage to dopamine neurons within the nigrostriatal bundle (projects to caudate and putamen) Slow movements and postural problems r...
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