Term
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Definition
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Term
| caudate + putamen + globus pallidus = |
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Definition
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Term
| putamen + globus pallidus = |
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Definition
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Term
| The extrapyramidal system |
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Definition
| The basal ganglia include a collection of gray matter nuclei in the diencephalon and mesencephalon (midbrain). It does not include the pyramidal or corticospinal tract. |
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Term
| The basal ganglia are highly connected to what parts? |
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Definition
| With the cortex and thalamus |
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Term
| How many neuronal circuits or channels in which different cortical areas connect with different parts of the basal ganglia, are there? |
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Definition
| Research has identified 4 parallel “channels”, each with distinct functions. |
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Term
| The basal ganglia clearly play an important role in what? |
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Definition
| In motor control (motor channel), as evidenced by persons with lesions of the basal ganglia who demonstrate abnormalities such as tremor, rigidity, difficulty in initiating voluntary movements, bradykinesia, ballismus, and choreoathetoid movements. |
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Term
| The basal ganglia also play a role in the: |
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Definition
a. control of eye movements (occulomotor channel),
b. cognitive functions (prefrontal channel)
c. emotional functions (limbic channel),
in addition to
d. motor control (motor channel) |
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Term
| Does the basal ganglia have direct connections to the motor neurons in the spinal cord? |
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Definition
| There is no direct connections to the motor neurons in the spinal cord, therefore stimulation of basal ganglia neurons does not directly cause movements. |
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Term
| The basal ganglia is best known for its function in... |
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Definition
| In motor control; however, it also plays a role in cognitive functions and emotion. |
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Term
| Formulation of general motor plans |
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Definition
A. Determine which general plans are appropriate for movement and which general motor combinations are available to achieve a motor goal.
B. Dysfunction of the loop decomposes behavior into isolated motor acts (similar to cerebellar dysfunction). |
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Term
| Execution of specific motor plans |
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Definition
| The basal ganglia determine how much scaling of motor effort is required for movement and when the quality of the movement is appropriate for automatization. |
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Term
| Scaling of motor intensity |
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Definition
A. This function involves helping bring about a smooth integration of programmed movement and postures that make up the learned motor acts.
B. Dysfunction of the motor loop results in movement of inappropriate rates, amplitudes and duration. |
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Term
| Automatic execution of learned motor plans |
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Definition
A. This function involves the automatization of learned motor acts such as handwriting.
B. Dysfunction means that much more mental effort must be applied during skilled movement, because all learned acts must proceed under voluntary guidance. |
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Term
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Definition
| Regulation of eye movement |
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Definition
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Definition
| Regulation of emotions and motivation |
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Term
| The caudate, putamen, globus pallidus (corpus striatum) which form the largest part of the basal ganglia, do they have means to directly affect the activity of lower motor neurons? |
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Definition
| They have no means to directly affect the activity of lower motor neurons. The basal ganglia have output to the motor cortex, which, in turn, controls the activity of extrapyramidal upper motor neuronal pathways (as well as the pyramidal or corticospinal tract). |
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Term
| The main inputs to the basal ganglia are to... |
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Definition
| Caudate and Putamen (striatum) |
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Term
| The main inputs to the basal ganglia come from... |
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Definition
| The cortex and thalamus and are excitatory (glutamatergic). Significant inputs also come from the substantia nigra pars compacta and are dopaminergic. |
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Term
| The main outputs from the basal ganglia are from the... |
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Definition
| The globus pallidus interna and the substantia nigra pars reticulata. The main output pathways are inhibitory (GABAergic) and project to the thalamus (ventral lateral and ventral anterior), the reticular formation, and the superior colliculus. Acetylcholinergic neurons in the striatum also play important roles in basal ganglia function. |
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Term
| The main anatomical/functional circuitry in the basal ganglia is separated into two pathways called... |
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Definition
| Called the direct and indirect pathways. A third pathway, termed the substantia nigra circuit helps modulate activity the direct and indirect pathways. |
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Term
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Definition
| Lack of inhibition of thalamic neurons and lack of inhibition of subthalamic neurons. |
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Term
| The result of the direct pathway is... |
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Definition
| In the motor channel this will mean increased movement. In the prefrontal channel it will mean increased cognitive function, and in the limbic channel, it will mean increased emotions. |
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Term
| The result of the indirect pathway is... |
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Definition
| In the motor channel this will mean decreased movement. In the prefrontal channel it will mean decreased cognitive function, and in the limbic channel, it will mean decreased emotions. |
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Term
| Substantia Nigra Pars Compacta Circuit |
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Definition
This pathway excites caudate/putamen neurons of the direct pathway (these neurons have the D1 receptors) and inhibits caudate/putamen neurons of the indirect pathway (these neurons have the D2 receptors).
e. Death of neurons of the substantia nigra pars compacta (and subsequent loss of dopamine in the striatum) occurs in Parkinson's disease. |
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Definition
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Term
| Lesions of the basal ganglia result in what are referred to as... |
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Definition
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Term
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Definition
(slowed movements) also see hypokinesia (decreased amount of movement) and akinesia (absence of movement)
- caused by increased inhibitory output of the basal ganglia to the thalamus (decrease in the direct pathway or increase in the indirect pathway) |
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Term
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Definition
twisting movements of the limb, face and, trunk.
- Associated with Huntington’s disease, perinatal hypoxia involving the basal ganglia, antipsychoitic medications, anitemetic medications, Levadopa |
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Term
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Definition
(means dance), continuous involuntary movements that have a fluid or jerky quality, but constantly vary. Can range from fidgeting or restless movements to frantic “break dancing”.
- Associated with Huntington’s disease, perinatal hypoxia involving the basal ganglia, antipsychoitic medications, anitemetic medications, Levadopa, infarct or focal lesion of the basal ganglia, systemic lupus erythematosus. |
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Term
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Definition
Movements of proximal limb muscles with larger-amplitude and more flinging quality than chorea.
- Usually it is unilateral due to a unilateral lesion to the contralateral subthalamic nucleus. Lesion of the subthalamic nucleus decreases inhibition of the thalamus |
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Term
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Definition
Rhythmic or semirhythmic oscillating movements.
- Can be classified as resting (Parkinson’s), postural, or intention, can have many causes. |
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Term
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Definition
– Increased resistance to passive movement of a limb.
Rigidity caused by basal ganglia disorders is referred to as plastic, waxy, or lead-pipe; meaning that it is fairly continuous throughout attempts to move the limb. |
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Term
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Definition
| Sustained assumption of abnormal, often distorted, positions of the limbs trunk or face. Can be generalized or focal. Associated with basal ganglia dysfunction. |
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Term
| Common Basal Ganglia Disorders are: |
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Definition
Parkinson’s Disease - slowed
Huntington’s Disease (Huntington’s Chorea)- fast
Ballism or Hemiballism - fast |
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Term
| Does electrical stimulation of the cerebellum cause sensation and movement? |
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Definition
Causes no sensation and rarely causes movement.
o This is because like the basal ganglia, cerebellar neurons have no direct connections to spinal cord ventral horn motoneurons.
•The cerebellum receives continuously updated information from the higher brain centers on the intended motor program. |
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Term
| Does the cerebellum receive continuous sensory information from several sensory modalities? |
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Definition
| It receives continuous sensory information from several sensory modalities (vestibular and visual systems; peripheral muscle spindles and tendon organs) regarding actual movement including body position, rate of movement, muscle length and muscle force. |
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Term
| • Cerebellar diseases and disorders (e.g. tumor, infarction, degeneration due to chronic alcoholism) produce: |
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Definition
o ataxia (incoordination of movements without paralysis)
o hypotonia to passive stretch
o intention tremors (loss of muscle synergy) |
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Term
| Overall Functions of the Cerebellum are... |
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Definition
1. Compare actual and intended movements. Then when necessary, send appropriate corrective signals to the motor system to increase or decrease the levels of activation of specific muscle groups to make corrective movements.
2. Aid the cerebral cortex in planning sequential movements. While a movement is on-going the next sequential movement is planned a fraction of a second in advance, thus enabling movements to progress smoothly.
3. Participate in the process of learning coordinated movements. If a movement error is made, the cerebellar circuitry "learns" to adjust its output to produce a stronger or weaker movement, as appropriate, the next time the movement is performed.
4. Produce a synergy of movement. To produce smooth, coordinated muscle activation. |
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Term
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Definition
- Medial border is the vermis,
- Separated from the posterior lobe by the Primary Fissure |
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Term
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Definition
- Separated from the anterior lobe by the Primary Fissure
- Separated from the Flocculonodular lobe by the Posterolateral Fissure |
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Term
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Definition
- Can be observed on the ventral surface of the cerebellum
- consists of 2 Flocculi (flocculus is singular) and 1 nodulus
- Separated from the posterior lobe by the Posterolateral Fissure |
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Term
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Definition
| – These lie lateral to the nodulus and medial to the cerebellar peduncles. |
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Term
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Definition
| most lateral, projection neurons of the cerebrocerebellum |
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Term
| Globose and Emboliform (Interposed) Nuclei |
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Definition
| – intermediate, projection neurons of the spinocerebellum. |
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Term
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Definition
| medial, projection neurons of the vestibulocerebellum |
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Term
| The peduncles of the cerebeller are considered _______ matter. |
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Definition
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Term
| Superior Cerebellar Peduncle |
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Definition
mainly axons leaving the cerebellum,
“output pathway” |
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Term
| Middle Cerebellar Peduncle |
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Definition
mainly axons entering the cerebellum,
“input pathway” |
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Term
| Inferior Cerebellar Peduncle |
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Definition
mainly axons entering the cerebellum,
“input pathway and output” BOTH |
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Term
| Input Fibers to Cerebellum are: |
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Definition
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Term
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Definition
1. cortico-ponto-cerebellar tract
a. The ponto-cerebellar fibers originate from nuclei in the pons that receive input from the frontal, parietal, temporal, and occipital lobes of the cerebral cortex. The enter the cerebellum via the middle cerebellar peduncle.
2. dorsal (posterior) spinocerebellar tract and ventral (anterior) spinocerebellar tract
a. Axons of the DSCT arising from cell bodies in the spinal cord (Clarke’s column) enter the cerebellum via the inferior peduncle. The spinal cord neurons receive input from peripheral proprioceptors in the trunk and lower extremities
b. Axons arising from cell bodies in the spinal cord enter the cerebellum via the superior cerebellar peduncle.
3. spinocuneocerebellar tract and rostral spinocerebellar tract
a. Axons arise from neurons in the cuneate nuclei enter the cerebellum via the inferior cerebellar peduncle. Neurons in the cuneate nucleus receive input from peripheral proprioceptors in the upper trunk and upper extremities
b. Axons arising from neurons in the cervical spinal cord enter the cerebellum via the inferior and superior cerebellar peduncles.
4. vestibular nerve
a. A subset of vestibular nerve axons enter the cerebellum via the inferior cerebellar peduncle. |
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Term
| cortico-ponto-cerebellar tract |
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Definition
| The ponto-cerebellar fibers originate from nuclei in the pons that receive input from the frontal, parietal, temporal, and occipital lobes of the cerebral cortex. The enter the cerebellum via the middle cerebellar peduncle. |
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Term
| dorsal (posterior) spinocerebellar tract and ventral (anterior) spinocerebellar tract |
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Definition
a.Axons of the DSCT arising from cell bodies in the spinal cord (Clarke’s column) enter the cerebellum via the inferior peduncle. The spinal cord neurons receive input from peripheral proprioceptors in the trunk and lower extremities
b. Axons arising from cell bodies in the spinal cord enter the cerebellum via the superior cerebellar peduncle. |
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Term
| spinocuneocerebellar tract and rostral spinocerebellar tract |
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Definition
Axons arise from neurons in the cuneate nuclei enter the cerebellum via the inferior cerebellar peduncle. Neurons in the cuneate nucleus receive input from peripheral proprioceptors in the upper trunk and upper extremities
b. Axons arising from neurons in the cervical spinal cord enter the cerebellum via the inferior and superior cerebellar peduncles. |
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Term
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Definition
| A subset of vestibular nerve axons enter the cerebellum via the inferior cerebellar peduncle. |
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Term
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Definition
| Arise from cell bodies in the inferior olivary nucleus. These fibers are important in the role of the cerebellum in learning motor tasks. Their input is from the cortex, basal ganglia, red nucleus and other extrapyramidal pathways. The enter the cerebellum via the inferior cerebellar peduncle |
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Term
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Definition
| (cerebrocerebellum) – Axons project through the superior cerebellar peduncle to contralateral thalamus (VL) and red nucleus. Thalamic neurons then send axons to motor cortex and association cortices (contralateral to cerebellar nuclei). |
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Term
| Globose and Emboliform (Interposed Nuclei |
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Definition
| (spinocerebellum) - . Axons project through the superior cerebellar peduncle to contralateral thalamus (VL), red nucleus, and reticular formation. Thalamic neurons then send axons to motor cortex and association cortices (contralateral to cerebellar nuclei). Motor cortical and red nucleus neurons send crossed axons to the spinal cord (ipsilateral to cerebellar nuclei). Thus, interposed nuclei modulate control of ipsilateral limb |
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Term
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Definition
| vestibulocerebellum) - . Axons project through both the superior and inferior cerebellar peduncles. The superior or uncinate pathway axons project to the thalamus (bilateral VL) and the tectum (contralateral). The inferior or juxtarestiform body project to the ipsilateral vestibular nuclei and reticular formation. |
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Term
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Definition
| the cerebellar cortex consists of 3 layers with 5 cell types, a dual-input system (mossy and climbing fibers) , and a single-output system (Purkinje cell axons). |
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Term
| Cerebellar cortex is made up of what layers? |
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Definition
Molecular layer
Purkinje cell layer
Granular cell layer |
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Term
| The molecular layer has what cells? |
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Definition
A. stellate cells – receive excitatory inputs from parallel fibers and send inhibitory outputs to Purkinje cells
B. basket cells – receive excitatory input from parallel fibers and send inhibitory outputs to Purkinje cells
C. parallel fibers (axons of granule cells) – Nonmyelinated axons that bifurcate in a T-like manner and running perpendicular to Purkinje cell dendrites. The form excitatory synapses
D. dendrites of Purkinje cells – they fan out in a single plane in this layer receiving input from stellate, basket and granule cells |
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Term
| The Purkinje cell layer has what cells? |
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Definition
| Purkinje cell bodies - their axons constitute the sole output of the cerebellar cortex. They project ipsilateral to the deep cerebellar nuclei (especially the dentate) where they form inhibitory synapses |
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Term
| The Granular cell layer has what cells? |
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Definition
A. granule cells – are the only excitatory cells in the cerebellar cortex. Axons are called parallel fibers, receive excitatory input from mossy fibers
B. Golgi cells – receive excitatory input from granule cell parallel fibers (in the molecular layer) and provide feedback inhibition to granule cell dendrites
C. glomerulus - a synaptic processing unit consisting of granule cell, Golgi cell and mossy fiber. |
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Term
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Definition
| – receive excitatory inputs from parallel fibers and send inhibitory outputs to Purkinje cells |
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Term
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Definition
| receive excitatory input from parallel fibers and send inhibitory outputs to Purkinje cells |
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Term
| parallel fibers (axons of granule cells) |
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Definition
| Nonmyelinated axons that bifurcate in a T-like manner and running perpendicular to Purkinje cell dendrites. The form excitatory synapses |
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Term
| dendrites of Purkinje cells |
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Definition
| they fan out in a single plane in this layer receiving input from stellate, basket and granule cells |
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Term
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Definition
| their axons constitute the sole output of the cerebellar cortex. They project ipsilateral to the deep cerebellar nuclei (especially the dentate) where they form inhibitory synapses |
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Term
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Definition
| are the only excitatory cells in the cerebellar cortex. Axons are called parallel fibers, receive excitatory input from mossy fibers |
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Term
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Definition
| receive excitatory input from granule cell parallel fibers (in the molecular layer) and provide feedback inhibition to granule cell dendrites |
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Term
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Definition
| a synaptic processing unit consisting of granule cell, Golgi cell and mossy fiber. |
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Term
| The cerebellar cortex can also be broken down into 3 functionally significant regions: |
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Definition
1. vestibulocerebellum
2. spinocerebellum
3. cerebrocerebellum |
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Term
| VESTIBULOCEREBELLUM location: |
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Definition
| Known as the flocculonodular lobe and the archicerebellum |
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Term
| VESTIBULOCEREBELLUM inputs: |
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Definition
Via the inferior cerebellar peduncle.
1. Semicircular canals in the inner ear (for information regarding changes in head position)
2. Otoliths in the utricle and saccule of the inner ear (for information about the orientation of the head relative to gravity)
3. Visual system (lateral geniculate and superior colliculus) |
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Term
| VESTIBULOCEREBELLUM outputs: |
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Definition
Via the fastigial nucleus through the superior and inferior cerebellar peduncles
1. One output is to vestibular nuclei and on to the medial longitudinal fasciculus, a pathway that projects rostrally to nuclei of cranial nerves III, IV and VI to participate in the vestibulo-ocular reflex (VOR).
2. A second output is projects caudally as the medial vestibulospinal tract to motor nuclei of neurons controlling axial musculature. |
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Term
| VESTIBULOCEREBELLUM functions: |
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Definition
1. Maintains equilibrium and control of axial (proximal) muscles to maintain balance
2. Coordinates eye and head movements (VOR)
3. Maintains upright posture. |
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Term
| SPINOCEREBELLUM location: |
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Definition
| Called the paleocerebellum is phylogenetically the second oldest part of the cerebellum. It is the intermediate region, including part of the vermis and the cerebellar cortices just lateral to the vermis. This region receives detailed input regarding a movement as it actually occurs as well as what the command signals from the cortex actually were. This region carries out the "comparator function" of the cerebellum. |
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Term
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Definition
Via the superior and inferior cerebellar peduncle
1. Vermal and intermediate zone: receive input from peripheral proprioceptors (spindles and tendon organs) via the dorsal spinocerebellar tact (DSCT), ventral spinocerebellar tract (VSCT), and cuneocerebellar tract regarding actual movement. |
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Term
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Definition
via the globose and emboliform (interposed) nuclei through the superior cerebellar peduncle
1. Vermal zone: to deep cerebellar nuclei and on to the midbrain reticular formation to influence motor pathways controlling axial musculature (medial and lateral reticulospinal tracts) for "framework" or trunk movement.
2. Intermediate or paravermal zone: to deep cerebellar nuclei and on to the red nucleus and to the thalamus and sensorimotor cortex to influence motor pathways controlling distal musculature for goal-directed activity (rubrospinal and corticospinal tracts). |
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Term
| SPINOCEREBELLUM functions: |
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Definition
1. Contributes to modulation and control of the execution of a movement by providing corrections both to the command centers in the sensorimotor cortex and to the motoneurons in the spinal cord. (control of ongoing movements)
2. Regulates muscle tone by influence of descending pathways on gamma motoneurons that (innervate muscle spindles). |
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Term
| CEREBROCEREBELLUM location: |
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Definition
| Called the neocerebellum, it is the phylogenetically the newest cerebellar area and consists of the lateral cerebellar cortices. |
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Term
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Definition
Via the middle cerebellar peduncle
1. Exclusively from sensory and motor cortex by way of contralateral pontine nuclei (the cortico-ponto-cerebellar tract, a crossed pathway). |
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Term
| CEREBROCEREBELLUM outputs: |
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Definition
via the dentate nucleus through the superior cerebellar peduncle
1. To the contralateral thalamus and sensorimotor cortex to influence neurons of the corticospinal tract. |
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Term
| CEREBROCEREBELLUM function: |
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Definition
| 1. Formulation of motor plans and initiation of movements. |
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Term
| Signs of cerebellar dysfunction: |
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Definition
A. Hypotonia: floppy, loose-jointed, rag-doll appearance with pendular reflexes; patient appears inebriated
B. Disequilibrium: loss of balance, characterized by gait and trunk dystaxia
C. Dyssynergia: loss of coordinated muscle activity that includes:
1. dysarthria:
2. dystaxia (ataxia):
3. dysmetria:
4. dysdiadochokinesia:
5. nystagmus:
6. decomposition of movement:
7. rebound or lack of check:
8. Nausea and Vomiting: |
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Term
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Definition
| Associated with cerebellar hemorrhages and lesions to the vetibulocerebellum. Sometimes referred to as “fatal gastroenteritis”. |
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Term
| rebound or lack of check: |
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Definition
| Results from the inability to adjust to changes in muscle tension (test by having the subject flex his forearm at the elbow against resistance; sudden release results in the forearm striking the subject's chest). |
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Term
| decomposition of movement: |
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Definition
| Consists of breaking down a smooth muscle act into a number of jerky awkward component parts |
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Term
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Definition
| A form of dystaxia consisting of to-and-fro eye movements (ocular dysmetria) |
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Term
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Definition
| inability to perform rapid alternating movements (e.g., rapid supination and pronation) |
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Term
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Definition
| Occurs during a voluntary movement (a type of dysmetria); gets worse as subject approaches his target. |
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Term
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Definition
| inability to arrest muscular movement at the desired point (also called past-pointing) |
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Term
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Definition
| lack of coordination in the execution of voluntary movement (e.g., gait, trunk - truncal, and leg/arm ataxia - appendicular) |
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Term
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Definition
| difficulty speaking; slurred or scanning speech |
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Term
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Definition
| loss of coordinated muscle activity |
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Term
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Definition
| loss of balance, characterized by gait and trunk dystaxia |
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Term
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Definition
| floppy, loose-jointed, rag-doll appearance with pendular reflexes; patient appears inebriated |
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