Upgrade to remove ads
Only $35.99/year

Lecture 21: Modulation of Movement by the Basal Ganglia

Terms in this set (41)

The basal ganglia consists of four regions:
Striatum; substantia nigra reticulata; globus pallidus; subthalamic nucleus
Striatum consists of
Caudate and putamen
The input structure of the basal ganglia from cortex is
Striatum
The output structures of the basal ganglia are
Substantia nigra and globus pallidus
Globus pallidus internal segment projects to
Thalamus
Globus pallidus projects to thalamus which projects to
Cortex
Substantia nigra reticulate projects to the
Superior colliculus of midbrain
Superior colliculus controls
Eyes and head movements
Nearly all regions of the cerebral cortex project directly to the striatum using _____ pathway
corticostriatal
Striatum integrates
Sensory and motor input
Dopamine neurons project from
Substantia nigra compacta
_____ are the major output neuron of the striatum
Medium spiny neurons
Medium spiny neurons receive cortical input from
Glutamate pyramidal neurons (spine head)
Medium spiny neurons receive midbrain input from
substantia nigra compacta dopamine neurons (spinen neck)
Medium spiny neurons from striatum are inhibitory (GABA) and project to
Substantia nigra reticulata and Globus pallidus
Substantia nigra reticulate neurons are inhibitory (GABA) and project to
Superior colliculus
Globus pallidus internal segment neurons are inhibitory (GABA) and project to the
Thalamus
Thalamic neurons are excitatory (glutamate) and project to
Frontal cortex
GABA neurons from the globus pallidus external segment project to the
Subthalamic nucleus
Subthalamic neurons use glutamate and project to the
globus pallidus internal segment
True or false

Substantia nigra and globus pallidus are spontaneously active at high levels to prevent unwanted movement
True
Cortical input to striatum inhibits basal ganglia output, which causes
Disinhibition (activation of relay cells in the thalamus and an activation of upper motor neurons to send commands to lower motor circuits and neurons)
Saccade means
Rapid, orienting movements of the eyes
Caudate of striatum projects GABA neurons to substantia nigra reticulate, which projects GABA neurons to superior colliculus, which projects glutamate neurons to
brain stem horizontal and vertical gaze centers
True or false

Reticulate inhibition and colliculus disinhibition precede saccade
True
Normally, tonically active substantia nigra reticular suppresses unwanted
Saccades
Direct or indirect pathway initiates volitional movement?
Direct pathway
Indirect pathway
Supresses unwanted or inappropriate movements
True or false

Dopamine can be both excitatory via D1 receptors or inhibitory via D2 receptors
True
D1 receptors are associated with the _____ pathway and D2 receptors are associated with ______ pathway
Direct, indirect
What does dopamine do overall in the basal ganglia?
Decreases inhibition and promotes movement
True or false

D1 activation enhances direct pathway of facilitating movement while D2 activation disinhibits direct pathway (suppresses inhibition) to facilitate movement
True
Parkinson's disease:
Hypokinetic movement (rigidity, resting tremor, bradykinesia, postural instability) loss of nigrostriatal dopamine neurons; cause is largely idiopathic
Huntington's disease
Hyperkinetic movement (chorea or rapid, jerky movements), autosomal dominant, mutation of gene for protein Huntingtin (chromosome 4; CAG repeats leads to polyglutamine)
True or false

In Parkinson's disease, loss of dopamine leads to hyperactive globus pallidus internal segment and excessive inhibition of the thalamus. Globus pallidus internal segment is hyperactive via hyperactive Subthalamic nucleus and loss of direct inhibition from striatum
True
True or false

In Huntington's disease, loss of indirect pathway neurons from striatum to globus pallidus external segment leads to disinhibition and hyperactivity. Hyperactive globus pallidus external segment leads to hypoactive globus pallidus internal segment and
True
There are 4 basal ganglia loops:
Body movement via putamen (motor cortex-movement), Occulomotor movement via caudate (frontal eye fields-eye movement), Prefrontal loop via anterior caudate (prefrontal cortex-cognition), limbic loop via ventral striatum (anterior cingulate cortex-motivated behavior)
In Parkinson's disease which structures are hyperactive
Globus pallidus internal segment and subthalamic nucleus
In Parkinson's disease which structures are diminished
Substantia nigra compacta and Striatum to Globus pallidus internal
In Huntington's disease, which structure is hyperactive
Globus pallidus external segment
In Huntington's disease, which structures are diminished
Striatum to globus pallidus external segment
Sets found in the same folder