21916047
Description
Flashcards by Marissa Alvarez, updated more than 1 year ago
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Created by Marissa Alvarez
about 4 years ago
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| Question | Answer |
| 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)
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| 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)
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| 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 |
| 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 |
| 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 |
| 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)
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| 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)
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| 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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