One mechanism of central pacern generamon 1 network

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Unformatted text preview: voluntary movement (akinesis), but no trouble responding to external cues! Causes of Parkinsons Disease •  Proximate (direct) Cause? –  Neuropathy of dopanergic neurons in the substanMa nigra •  UlMmate (underlying) Cause? ―  Free radical damage? ―  From toxins (MPTP)? ―  From Fe increase? ―  From increased immune cell acMvity? What does akineses tell us about how motor acMvity is iniMated in humans? •  Central or peripheral control? CPG versus Peripheral Example •  Each Movement is reflex response, walking on flat ground. One Mechanism of Central Pacern GeneraMon + 1  ­ •  Network oscillators –  Closed ­loop model: 1, 2, 3 pacern  ­ 3 To flexor  ­ 2 To extensor Analogy •  Think of the Inhibitory pathway as your parents, and the Excitatory pathway as your friends. –  If a group of your parents’ friends take them away for a weekend out, the friends are like glutamate because they are removing your inhibitory control. –  When your friends come over for the party you’re throwing. your excitatory pathway is uncontrolled because your inhibitory pathway has been incapacitated. BG “Disinhibition” Basal Ganglia: a closed ­loop CPG for movement Within the substanMa nigra. Selects one movement, inhibits the rest. Dopanergic Neuron +  ­ A  ­ B + Striatal Neuron Motor cortex neuron DisinhibiMon To body motor neurons Basal Ganglia: a closed ­loop CPG for movement Within the substanMa nigra: Dopanergic Neuron  ­ Striatal Neuron + A  ­ B  ­ Motor cor...
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