Basal Ganglia Anatomy
What are at least 3 primary Basal Ganglia (BG) neurotransmitters?
Glutamate, dopamine, GABA, acetylcholine, substance P
What is the difference in main Fxs between the basal ganglia and the cerebellum?
Basal ganglia: regulates movement initiation (excitation or inhibition of movement)
Cerebellum: coordinates the timing and precision of movements (movement fluidity)
The basal ganglia balances _______ and _______ through its specific circuitry of multiple interconnected loops to the striatum, GP, thalamus, motor cortex, and cerebellum.
inhibition and excitation
Slow, involuntary twisting of axial and speech muscles.
Athetosis
Disorder involving a resting tremor, cogwheel rigidity, bradykinesia, and facial expression paucity.
Parkinson's disease
What role does the subthalamus (STH) play in basal ganglia functioning?
Providing excitatory input (glutamate neurotransmitter)
The basal ganglia modulates and refines motor complex activity through a _______ _____ in the thalamus.
Feedback loop
How many total BG loops are there?
4 (1st, 2nd, 3rd and 4th)
What is chorea, and what disorder is it associated with?
Rhythmic, quick, and graceful-looking involuntary movements; associated with Sydenham chorea and Huntington chorea.
Involuntary movements blending multiple structures, caudate degeneration, cognitive deficits (dementia characteristics), dysarthria, and dysphagia.
Huntington chorea
Structure Fx: planning the execution of movement, learning, memory, reward, motivation, emotion, and romantic interaction.
Caudate Nucleus (CN)
How does the basal ganglia refine cortical motor activity?
Through suppression of competing movements (inhibition), regulation of associated motor movements (excitation), and regulation of cognitive function (impulsivity)
What is the structural order of the first loop in BG circuitry?
Projections from the motor cortex go to the neostriatum, GP, thalamus, and the motor cortex
Dystonia (torticollis)
What is tardive dyskinesia?
Involuntary movements of facial and lingual muscles from the use of psychotropic drugs used to treat mental illnesses.
The globus pallidus (GP) regulates ______ (voluntary/ involuntary) movement.
Voluntary
The basal ganglia influences ________ (ipsilateral/ contralateral) cortical areas, then decussates in the medulla before descending efferents go down the spinal cord.
ipsilateral
What will lesions at various circuitry points lead to?
A variety of different, but involuntary movement disorders (e.g., tremor, chorea, athetosis)
What is myoclonus?
Repeated and isolated muscle contractions, mostly involving small muscles.
What is Wilson's disease?
A progressive, early-onset disease involving involuntary motor movements due to copper metabolism errors (Kayser-Fleischer ring in the iris), muscular rigidity, tremor, dysarthria, dementia, and the degeneration of BG and the liver.
Structure responsible for reward-seeking, learning, addiction, and movement (eye movements and motor planning)
Substantia nigra (SN)
Motor symtpoms associated with basal ganglia lesions will appear ________ (ipsilateral/ contralateral) to the lesion site.
contralateral
What is the order of structures in the BG feedback loop, which connects the BG to different parts of the brain?
Motor cortex->basal ganglia->thalamus->back to motor cortex
Alternating motor activity in one or more body parts; degenerative changes in the substantia nigra (SN); and uncontrollable movements during voluntary movement (usually resulting from cerebellar lesions).
Tremors
Symptoms: brainstem cellular degeneration, gaze palsy (impaired down gaze), imbalance, bradykinesia, impaired gait control, dysarthria/ dysphagia, and personality changes.
Progressive supranuclear palsy