Deep Brain Stimulation Thalamus Subthalamus 1

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The Thalamus

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, , gysts s t s d neuroscience & medicineiali rolo iel mechanism c u s f e e r e e p n s, s ists, arch n th t den ient , rese sted i u t s GPe fibers projecting to the STN are sc ns re for euro urge inte activated by STN stimulation. This inhibits STN n ros ll neurons (Alexander et al. 1990; DeLong 1990). This a u ne d for decreases the activity of inhibitory GPi an neurons, result in increased thalamocortical neuro-

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nal activities. TRANSLATIONAL PHYSIOLOGY Single Pulse Stimulation of the Human Subthalamic Nucleus Facilitates the Motor Cortex at Short Intervals Ritsuko Hanajima et al, Neurophysiol 2004.

When a voluntary movement is about to be initiated by cortical networks, a signal is sent from the motor cortex through the cortico-subthalamo-pallidal pathway to activate GPi neurons extensively. Ther result is the inhibitionf of their targets .

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Another signal through corticostriato-pallidal pathway (direct pathway) is sent to the GPi to inhibit a specific population of pallidal neurons. A central population of pallidal neurons disinhibit their target neurons in the thalamus . Thus only the selected motor “software” is executed at the selected timing, Excitatory Cortical Inputs to Pallidal Neurons Via the Subthalamic Nucleus in the Monkey ATSUSHI NAMBU et al, J Neurophysiol, 2000.

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Deep Brain Stimulation Research Review 7 web pages and 17 A4 pdfs on DBS mechanism on www.thalamus.ro in Thalamus in Neurology, Neurosurger and Pharmacology Site Section

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HFS in GPi does not necessarily lead to decreased inhibitory pallidal output and facilitation of thalamic targets. HFS in GPi appeared to reduce the number of bursts and the number of spikes per burst. It is a posib.ility that the symptomatology is an abnormal pattern of activity, rather than a reduction in thalamic activity as a result of an increase in mean pallidal discharge rate. It may be that the beneficial effects are a consequence of the interruption of abnormal patterns of activity in corticothalamic circuits. MARJORIE E. et alJ Neurophysiol, 2003,Effects of High-Frequency Stimulation in the Internal Globus Pallidus on the Activity of Thalamic Neurons in the Awake Monkey A possibility is that the STN stimulation activates STN projection fibers to GPe . This pathway facilitates the GPe neurons and caused disinhibition of the thalamocortical pathway. TRANSLATIONAL PHYSIOLOGY Single Pulse Stimulation of the Human Subthalamic Nucleus Facilitates the Motor Cortex at Short Intervals Ritsuko Hanajima et al, Neurophysiol 2004. cortex, thalamic CM/Pf glutamate

STN neuron two types of dendrites

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substantia nigra dopamine

dorsal raphe serotonine tegmentum acetylcholine