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34 Cards in this Set
- Front
- Back
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What is the function of the Corticospinal system?
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Corticospinal:
Execution of voluntary movement -velocity and force of muscle contraction |
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What is the function of the cerebellum?
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Cerebellum
1.Postural Control 2.Coordination of voluntary movement -timing of movements across different muscle groups |
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What is the function of the Basal Ganglia?
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Basal Ganglia:
Provide motor complexity and flexibility -altering routing, automatic movements in response to needs or motivation |
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The Basal Ganglia and related structures are associated with:
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Somatic motor functions
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The input nuclei of the Basal Ganglia are:
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Striatum (Caudate and Putamen)
Inputs include massive projections from all four lobes of cerebral cortex Efferent fibers from striatum project to other nuclei of the basal ganglia. |
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The output nuclei of the Basal Ganglia are:
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Medial Pallidal Segment (MPS)
Substantia Nigra, pars reticulata (SNr) MPS and SNr receive inputs from stratium and intrinsic nuclei. Efferent fibers project to the VA and VLa nuclei of the thalamus. |
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What are the two intrinsic nuclei?
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Lateral Pallidal Segment
Subthalamic Nuceli They ONLY communicate with other Basal Ganglia nuclei. |
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What are the (4) TURE Basal Ganglia Structures?
What (2) structures are often associated (clinically) with the Basal Ganglia? |
TRUE Structures:
-Caudate, Putamen, Globus Pallidus, Amygdala Associated (clinical) structures: subthalamic nuceli substantia nigra |
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What effect on movement does the Direct Pathway have?
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The DIRECT pathway excites descending motor pathways to facilitate movement.
Neurons in the striatum project directly to the MPS and SNr. |
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What effect on movement does the Indirect Pathway have?
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INDIRECT pathway decreases the excitation of the descending motor pathways and SUPPRESSES movement
Neurons in the striatum project to the intrinsic nuclei, which then project to output nuclei (MPS and SNr) |
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List the (2) major input sources which arrive at the striatium (caudate and putamen).
What are their respective neurotransmitters? |
1. Cerebral Cortex - Glutamate
2. Substantia Nigra, pars compacta - Dopamine |
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What are the two types of nurons found in the striatum?
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Spiny striatal neurons (provide most of the input to the striatum) - have dendritic spines!
Aspiny striatal neurons (local interneurons that DO NOT project outside of the striatum) |
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What is the function of Spiny Striatal Neurons?
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Spiny Striatal Neurons provide most of the output of the striatum.
The two classes of spiny striatal neurons produce different combinations of neurotransmitters: 1. GABA/Subtance P 2. GABA/Enkephalin |
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What is the function of Aspiny Striatal Neurons?
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Aspiny Striatal Neurons DO NOT project outside of the striatum.
Their main function is to modulate the activity of spiny striatal neurons |
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What are the Efferent Projections of the striatum:
DIRECT Pathway? INDIRECT Pathway? |
DIRECT - GABA Substance P spiny striatal neurons project directly to the MPS and SNr.
INDIRECT - a. GABA/Enkephalin spiny striatal neurons project to the LPS. --> b. Neurons in the LPS project to the STN and use GABA --> c. STN neurons project to the MPS and SNr and utilize glutamate. |
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Output of the Basal Ganglia.
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Output of the Basal Ganglia:
1. MPS and SNr project to VA and VLa of the Thalamus. --> (This is an INHIBITORY connection - GABA) 2. VA and VLa neurons project to the supplementary motor area (SMA). -->(Excitatory - Glutamate) Thalamus facilitates movement! The Basal Ganglia modulate the amount of excitatory input from the thalamus to the cortex. |
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Describe the effects of the Basal Ganglia have on modulation of Thalamic output and movement.
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Less inhibition of the thalamus - facilitates movement
More inhibition of the thalamus - suppresses movement. |
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The net effect of the DIRECT pathway is the _______ the basal ganglia's inhibitory input to the thalamus.
This results in ________ excitatory input from the thalamus to motor cortex which _________ movement. |
The net effect of the DIRECT pathway is the DECREASE the basal ganglia's inhibitory input to the thalamus.
-Neurons in the thalamus are DISINHIBITED. This results in INCREASED excitatory input from the thalamus to motor cortex, which FACILITATES movement. |
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The net effect of the INDIRECT pathway is the _______ the basal ganglia's inhibitory input to the thalamus.
This results in ________ excitatory input from the thalamus to motor cortex which _________ movement. |
The net effect of the INDIRECT pathway is the INCREASE of the basal ganglia's inhibitory input to the thalamus.
This results in DECREASED excitatory input from the thalamus to motor cortex which SUPPRESSES movement. |
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Striatal Efferents:
The Direct pathway projects to the ________. The Indirect pathway projects to the ____ |
Striatal Efferents:
The Direct pathway projects to the MPS and SNr. The Indirect pathway projects to the LPS. |
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What neurotransmitter does the Subthalamic nucleus release?
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Glutamate
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Where does the Subthalamic nucleus project to?
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MPS and LPS (Indirect Pathway)
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What neurotransmitter is released by the LPS?
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GABA
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Where does the LPS project to?
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STN (Indirect Pathway)
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What 3 types of neurons does Dopamine influence in the striatum?
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1. GABA/Substance P Spiny Neurons
2. GABA/Enkephalin Spiny Neurons 3. Acetylcholine-producing Aspiny Neurons |
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Where are the two different types of Dopamine receptors?
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D1 receptors - located on GABA/SP spiny neurons
D2 receptors - lovated on GABA/Enkephalin spiny neurons in the striatum. (Overall- Dopamine facilitates movement) |
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What happens when dopamine binds to D1 receptors?
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Dopamine binding increases the release of GABA/SP from spiny neurons projecting to MPS and SNr thereby preferentially pushing the Direct Pathway
(Overall- Dopamine facilitates movement) |
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What happens when dopamine binds to D2 receptors?
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dopamine binding reduces the release of GABA/Enkephalin from spiny neurons projecting to LPS thereby suppressing the Indirect Pathway
(Overall- Dopamine facilitates movement) |
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Cortical inputs to the basal gangli (corticostriate fibers) course predominantly in the _________ and to a lesser extent in the _________.
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Cortical inputs to the basal gangli (corticostriate fibers) course predominantly in the INTERNAL CAPSULE and to a lesser extent in the EXTERNAL CAPSULE.
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What is the mechanism of the Hypokinetic Model associated with Parkinson’s disease?
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loss of dopamine neurons results in a reduction in the transmission through the direct pathway and a preference for the indirect pathway
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What is the mechanism of the Hyperkinetic Model associated with Huntington’s disease and Hemiballism?
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STN destruction (Hemiballism) or loss of GABA/Enkephalin striatal neurons (Huntington’s) projecting to LPS result in decreased activity in the indirect pathway
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Define:
1. Chorea |
Chorea:
Nearly continuous, non-purposeful movements. Can be jerky of fluid |
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Define:
Ballismus |
Ballismus:
Large-amploitude, flinging movements of the proximal limb muscles. |
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Define:
Athetosis |
Athetosis:
Slow, twisting or writhing movements of the limbs, face, neck, trunk. Movements flow randombly from one part of the body to another. |
