Basal Ganglia Flashcards
What are the main structures involved in the Basal Ganglia
Caudate Putamen Globus Pallidus Substantia Nigra Subthalamic Nuclei
The striatum consists of
Caudate and putamen
What stuctures are considered the Lenticulate Nucleus
Putamen and Globus Pallidus
What structures are vascularized by the Lenticulate Artieries of the MCA
Lenticulate nucleus: Putamen and Globus Pallidus
Where can the Subthalamic Nuclei be found?
Midbrain-Diencephalic junction
Where is the substantia nigra be found
Midbrain
The substantia nigra has two parts. What are they and which part is located most ventral?
Pars compacta
Pars Reticularis*
What is the main role of the BG?
Motor control:
initiation and execution (scale) of movement and
Prevent unwanted movement
What are the extra roles/loops that the BG is involved with?
Eye movement loop
Goal-directed behavior loop
Social behavior loop
Emotional loop
All input to the BG is received via the
Striatum
The BG receives input from where?
Cerebral cortex (caudate receives from heteromodal association cortices and motor areas of frontal lobe [eye mvmt]
Putamen receives from parietal, occipital and temporal lobes, premotor and PriMC, and auditory association)
SNpc
Thalamus (intralaminar nu)
Subcortical structures (NT)
The cerebral cortex sends info to the striatum via what pathways?
Corticostriatal
The BG sends output info to
VL and VA nu of thalamus > frontal lobe (PriMC, PreMC, and SMA)
Intralaminar Nu of thalamus (motor relay)
Mediodorsal Nu (limbic loop)
Superior colliculus (eye mvmt [tectospinal])
What BG structures receive input and what structures send output info
Input: striatum
Output: GPi and SNpr
What is the direct pathway of the BG
INITIATES MOVEMENT
Cortex sends GLUT to striatum which inhibits GP and SNpr which allows thalamus to excite cortex and elicit movement
Normally, the GPi and SNpr ___________ the thalamus to _____________________________.
Inhibits
Prevent unwanted movement
Without control from the ________and______, the thalamus would send __________________ to the cortex
GPi and SNpc
Constant excitatory signals
What is the indirect pathway of the BG?
STOPS MOVEMENT
Cortex inhibits GPe via the striatum which stops the ability to inhibit the Subthalamic nu… then the cortex activates the Subthalamic nu to send excitatory signals to GPi and SNpr which stregthens inhibition of thalamus
What structure regulates the direct and indirect pathways of the BG? How?
SNpc has direct connection to the striatum
Modulates activity via dopamine release
Dopamine has an _______ effect in the indirect pathway and an __________ effect in the direct pathway: this will assist in the ______________
Inhibitory
Excitatory
Facilitation of movement
What is the function of ACH in the BG
Inhibits dopamine when appropriate
Can quickly interrupt ongoing motor behavior in response to salient environmental stim.
Function of the oculomotor loop
Higher control of eye movements: aids in spatial attention
Initiates fast eye movements toward an object (saccadic movement)
Basic oculomotor loop path
Post. Parietal and prefrontal cortex > caudate > GPi and SNpr > MD and VA nu > frontal and supplementary eye field
Function of goal directed behavior loop
Decision making, goal directed behavior, planning, action selection, learning
What loops are included in the pre-frontal loops
Goal directed behavior loop
Social behavior loop
Function of social behavior loop
Recognizes social cues, regulates self control, discriminates relevant and irrelevant info
Goal directed behavior and social behavior loops path
Dorsolateral, prefrontal cortex > anterior caudate > GPi (Goal-directed) and SNpr (social behavior) > MD and VA nu > dorsolateral prefrontal cortex
Function of the limbic/emotion loop
Links emotion to cognitive and motor systems; reward seeking; outcome predictions
Receives dopaminergic input from VTA
Describe the limbic loop path
Amygdala, hippocampus, orbitofrontal, anterior cingulate, temporal cortex > ventral striatum )nu accumbens) > ventral pallidum > MD nu > anterior cingulate, orbitofrontal cortex
Parkinson’s disease and Huntington’s disease are _______ dysfunctions
Basal ganglia
What tests would you preform to test the basal ganglia
Myotomes- motor control
Tone assessment- rigidity
Coordination assessment
Impairments seen with Basal Ganglia dysfunction
Incoordination Rigidity (posturing?) Dystonia Weakness Impaired motor control: synergies and impaired motor recruitment
