Lecture Fifteen - Basal Ganglia

Questão	Responda
Objectives	1. Identify and locate the components of the basal ganglia 2. Identify the neurotransmitters released from each nucleus in the basal ganglia 3. Understand the concept of 'disinhibition' 4. Learn the projection patterns of the cortico-striatal-thalamo-cortical loop 5. Understand the functions of the direct and indirect pathways in this loop
Basal ganglia 5 parts??	1. Caudate nucleus 2. Putamen 3. Globus pallidus 4. Subthalamic nucleus 5. Substantia nigra
Basal ganglia •Feedback loop between subcortical nuclei, thalamus, brainstem, and cerebral cortex • Control of ____ motor movements (action selection) • ____ of movement • ___-___ of motor and premotor outputs • Smoothly switch between behaviors	voluntary Anticipation Fine-tuning
Caudate nucleus •3 parts: ___, ___, __ • Head is continuous with the ____ • Tail terminates in the ___ Follows curvature of lateral ventricles •Dopaminergic inputs from ____ ___	head, body, tail putamen amygdala substantia nigra
Putamen •____ portion of the basal ganglia •Continuous with ___ nucleus • Connected by ___ ___ (fiber tract) •Caudate + Putamen = ___ ____	Outermost caudate internal capsule Dorsal Striatum
Striatal afferents (inputs) •____ fibers: excitatory inputs from PFC, premotor area, and primary motor cortex •_____ fibers: inputs from intralaminar nuclei •____ fibers: dopaminergic input from nigra •_____ fibers: limbic system input	Corticostriatal Thalamostriatal Nigrostriatal Amygdalostriatal
Striatal neurons •___ ___ neurons: • Principal neurons of the striatum (95% of striatum) Express ___ receptors Output neurons • ____ (inhibitory) *These cells fire in ___ of movement	Medium spiny dopamine GABAergic anticipation
Globus pallidus •Internal (GPi) and external (GPe) segments • Separated by ___ ___ ____ •Putamen + globus pallidus (GPe and GPi) = ___ nucleus	medial medullary lamina lenticular
Globus pallidus •Inputs from ____ •Sends outputs to the ___ •GABAergic • Tonically active to ___ unwanted movement at rest • Disinhibited by ___ ___ neurons Important for regulation of voluntary movement	striatum thalamus inhibit medium spiny Image: Gp (binary/octet-stream)
Subthalamic nucleus •Located ventral to the ____ •Inputs from ___ •Outputs to ___ ___ • Glutamatergic (___) •Action selection	thalamus GPe globus pallidus excitatory
Substantia nigra •Substantia nigra ("black substance") - dark appearance due to presence of ___ Pars compacta (SNc): • Releases ___ • Fine motor control •Axonal degeneration of SNc neurons = ___ disease Pars reticulata (SNr): • Releases ___ • ___ inhibition of motor outputs	neuromelanin dopamine Parkinson's GABA Tonic
Substantia nigra •Inputs: ____ •Outputs: • SNr sends ____ outputs to the thalamus and brainstem • Primary output of basal ganglia for ___ movements • SNc sends dopaminergic outputs to the striatum • DI receptors: ____ • D2 receptors: ____ • Fine motor control and ____ processing	Striatum GABAergic eye excitatory inhibitory reward Image: Sn (binary/octet-stream)
Direct pathway Motor circuit for __-___ of muscle activity • Motor cortex (sends excitatory output to ___ in striatum) • Striatum (sends inhibitory output to ___ & ___) • Globus pallidus internal (becomes _____, so stops inhibiting thalamus) • SNr (sends inhibitory output to ____) • Thalamus (sends ___ output back to motor cortex)	fine-tuning MSNs GPi & SNr DISINHIBITED thalamus excitatory
Image: Direct+Pathway+Covered (binary/octet-stream)	Image: Direct+Pathway (binary/octet-stream)
Indirect pathway • Motor circuit to prevent ____ muscle contractions from competing with voluntary movements Motor cortex (sends excitatory outputs to ___) Striatum (sends inhibitory outputs to __) Globus pallidus external (becomes ____ so stop inhibiting subthalamic nucleus) Subthalamic nucleus (sends excitatory outputs to ___) ___ of the inputs that GPi gets via the direct pathway Thalamus (sends ___ ___ outputs to motor cortex)	unwanted striatum GPe DISINHIBITED GPi Opposite reduced excitatory
Image: Indirect+Pathway+Covered (binary/octet-stream)	Image: Indirect+Pathway (binary/octet-stream)
Integration of the pathways Cortical activity signals onset of movement ___ pathway inhibits GPi and increases thalamic output (facilitation of cortically initiated movement) ___ pathway excites GPi and ___ thalamic output (suppression of antagonistic muscles/decreasing competing movements). **BOTH pathways are active at the __ time	Direct selects desired movement (action slection) Indirect prevents the undesired or unwanted movement decreases same Image: Both+Pathways (binary/octet-stream)
Parkinson's disease •Loss of ____ cells in SNc •Reciprocal input between SNc and striatum lost •Subthalamic nucleus becomes ____ (b/c GPe inhibition of STN is completely removed) •Increased excitatory outputs to __ •Greater inhibitory output from GPi to ____ •Thalamic output to the cortex is ____	dopaminergic hyperactive GPi thalamus reduced Image: Pd (binary/octet-stream)
Parkinson's disease •Loss of SNc dopaminergic neurons may be due to lesion, environmental toxin, or genetic causes •Rigidity may be caused by decreased control of ___ neurons that control motor neurons. Impaired ability to prevent ___ muscle activity. •____: reduced ability to initiate voluntary movement •____: involuntary movements (tremors, tics)	inhibitory competing Bradykinesia Dyskinesia Image: Pd2 (binary/octet-stream)
Deep brain stimulation ____ implantation of electrode into basal ganglia structures: • subthalamic nucleus (STN) • Internal segment of globus pallidus (GPi) •Levodopa-___ Parkinsons's symptoms	Stereotactic resistant

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Lecture Fifteen - Basal Ganglia

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	Criado por Marissa Alvarez mais de 4 anos atrás