"...Parkinson's disease is a neurodegenerative condition affecting dopaminergic neurons in the brain leading to Associated motor symptoms neurodegeneration means a progressive irreversible loss of neurons and in Parkinson's disease it is mostly the dopamine-producing neurons in the substantia nigra that's a lost for us to move signals are generated by the cerebral cortex that then pass through the motor pathways and lead to with our muscles and ultimately movement however this process needs to be regulated which is primarily the job of the basal ganglia the substantia nigra is a part of the basal ganglia which are a group of nuclei in the brain all normally there are two main Pathways the direct and indirect pathway the direct pathway is an excitatory pathway that facilitates movement the motor cortex sends excitatory signals via glutamate to the striatum the striatum sends inhibitory signals to the Globus pallidus internus substantia nigra pars reticulata via Gaba these two both release Gaba which normally inhibits Thalamus so in this path there is inhibition of the inhibition on the thalamus giving an overall increased activity of the thalamus which promotes movement the indirect pathway is instead an inhibitory pathway that's purpose is to terminate movement in this case there is an inhibitory Gaba signal from the striatum to the Globus pallidus external Tunis the Globus pallidus external is normally inhibits the subthalamic nucleus which normally stimulates the Globus pallidus internal this means that the indirect pathway increases the inhibitory effect of the Globus pallidus internus on the thalamus and so there is less signal from the thalamus and so there is less move in Parkinson's there is a gradual degeneration of neurons within the substantia nigra pars compacta these neurons release dopamine to the striatum in the striatum there are direct pathway neurons that have D1 dopamine receptors and are excited by dopamine and indirect pathway neurons that have dopamine D2 receptors and that inhibited by dopamine overall this means dopamine released from the past compactor..."
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