Basal Ganglia Flashcards
what are the two main feedback systems for refining motor system output?
Basal ganglia
Cerebellum
Basal ganglia lesions
result in hypo or hyperkinetic movement disorders
cerebellar lesions
Result in ataxia
basal ganglia circuit
information Coming from the pre-motor cortex
Goes to basal ganglia
goes to the thalamus
Goes back to the motor cortex
cerebellum circuit
information from the cortex
To the pons
To the cerebellum
To the thalamus
What is the basal ganglia?
A collection of gray matter nuclei located deep within the white matter of the cerebral hemispheres
Main components include the caudate nucleus , putamen, global pallidus, subthalamic nucleus, and substantia nigra
The basil ganglia, predicts what?
Predicts the effects of actions, then make and execute action plans
putamen
A large nucleus forming the lateral portion of the basal ganglia
there are cellular bridges that connect the putamen to the caudate nucleus
striatum
The caudate and the putamen joined together
Location of the Globus pallidus
medial to the putamen
globus palludis
pale globe
myelinated fibers
Internal and external segments
lenticular nucleus
putamen and globus pallidus
substantia nigra
In the midbrain just dorsal to the cerebral peduncles
ventral portion is called the substantia nigra pars reticulata
The dorsal portion is called the substantia nigra pars compacta
Parkinson’s is associated with the degeneration of which area?
Substantia nigra
Problem with dopamine production
Basal ganglia input
inputs to the basal ganglia arrive via the striatum
Glutamate from the cortical motor areas equals the excitation of the striatum
Basal ganglia output
exit via
globus pallidus internus
substantia nigra pars compacta
substatia nigra sends neurons to the
striatum, where they release dopamine
which adjust signals to the output nuclei
With appropriate inhibition of the target nuclei
globus pallidus internus inhibits
Motor thalamus, pedunculopontine nucleus, and midbrain locomotor region
putamen receives input from
Premotor cortex, and motor cortex
subthalamic nucleus and substantia nigra compacta process
information within the basal ganglia circuit
globus pallidus internus send output to
Motor areas of the cerebral cortex via the motor thalamus, PPN, and the midbrain locomotor region
Basal ganglia Motor circuit output, regulates
muscle contraction
Muscle force
Multi joint movements
Sequencing of movements
Why does the basal ganglia use three routes?
There are no direct outputs to the lower motor neurons
Three routes for basal ganglia output
Motor thalamus
pedunculopontine nucleus
midbrain locomotor region
basal ganglia and motor thalamus
The basal ganglia inhibits the motor thalamus
Allows normal level excitation through the lateral corticospinal and rubrospinal tracks
Allows normal control of voluntary movements
basal ganglia and PPN
Basal ganglia, inhibits pedunculopontine nucleus PPN
PPN inhibits the reticulospinal tracts
allows normal facilitation to the postural and girdle muscles
basal ganglia and mibrain locomotor region
Basal ganglia inhibits midbrain locomotor region
allows normal activation of reticulospinal tracts
allows normal facilitation of the stepping pattern generation
Basal ganglia loops
Contribute to full functioning of the basal ganglia
Predict future events
Control desired, and undesired behaviors
Motor Learning
shifting attention
Spatial working memory
motor loop links the
putamen, globus pallidus, ventral lateral thalamic nucleus to the motor and premotor cortex
oculomotor loop links
frontal and supplementary fields with the caudate body, substantia nigra reticularis, and the ventral anterior thalamic nucleus
role of the motor loop
Movement selection and action
Regulating-
muscle contraction
force
multi joint movements
sequencing
role of oculomotor loop
regulate spatial attention and eye movements
Reflexive prosaccades
Goal directed behavior loop
Goal Directed behavior
makes perceptual decisions
Plans and decides on actions in context
Social behavior loop
Recognition of social disapproval
Self-control
Discerning, relevant versus irrelevant information
Maintaining attention
Stimulus response learning
emotion loop
involved in reward seeking and addiction
Determines the value of stimulus
reward based behaviors
Monitors predictive errors
Pleasure seeking
ventral striatum links
limbic
Cognitive
Motor systems
excessive inhibition, you end up with
hypokinetic disorders
Parkinson’s
inadequate inhibition, you end up with
Hyperkinetic disorders
Huntington’s disease
dystonia
Tourette’s disorder
dyskinetic cerebral palsy
