Basal Ganglia

basal ganglia

group of subcortical nuclei that play a role in motor functions

What are the functions of the basal ganglia?

regulate motor control (i.e., speed, accuracy, start/stop, timing) and cognitive-motor functions (motor planning), regulate modulation of cortical information in facilitative or inhibitory manner

What are the structures of the basal ganglia?

striatum (caudate and putamen), lenticular nucleus (putamen and globus pallidus), substantia nigra, and subthalamus

What is the function of the striatum (caudate and putamen)?

receives motor information from the cerebrum, involved in motor reward

What is the function of the lenticular nucleus (globus pallidus and putamen)?

creates smooth movement patterns

What is the function of the substantia nigra?

refines and coordinates movement patterns

What is the function of the subthalamus?

inhibitory regulation (i.e., slowing down movements for accuracy and precision)

Which structure is identified by the pink outlines?

caudate (frontal-coronal view)

Which structure is identified by the blue outlines?

putamen (frontal-coronal view)

Which structure is identified by the red outlines?

globus pallidus (frontal-coronal view)

Which structure is identified by the yellow outlines?

subthalamus (frontal-coronal view)

Which structure is identified by the black outlines?

substantia nigra (frontal-coronal view)

Which structure is identified by the red arrow?

putamen (lateral view)

Which structure is identified by the blue bracket?

caudate (lateral view)

Which structure is identified by the red arrow?

horizontal fibers (lateral view)

Which structure is identified by the red arrow?

amygdaloid nucleus

What is the function of the horizontal fibers?

communication between caudate and putamen; designed this way to weave through internal capsule

What is the function of the amygdaloid nucleus?

associated with movement reward

afferent basal ganglia pathway

receiving pathway; information from the cortex is sent to the afferent nuclei of the caudate and putamen

reciprocal basal ganglia pathway

"back and forth” pathway; information shared between putamen and globus pallidus, putamen and caudate, caudate and substantia nigra, and substantia nigra and subthalamus

efferent basal ganglia pathway

“leaving” pathway; information leaves basal ganglia, traveling from substantia nigra and globus pallidus to the thalamus, then on to the cortex

Which basal ganglia pathway is identified in this drawing?

afferent pathway

Which basal ganglia pathway is identified in this drawing?

reciprocal pathway

Which basal ganglia pathway is identified in this drawing?

efferent pathway

What are the regulatory functions (loops) of the basal ganglia?

skeletomotor (speed, distance, force of movement), oculomotor (spatial perception with eye movements), pre-frontal (executive function with overall motor planning), limbic (motivation, emotional responses, and rewards with movement)

What are some conditions associated with basal ganglia damage / dysfunction?

dyskinesia (hyperkinesia, hypokinesia), Parkinson’s disease, Huntington’s disease

dyskinesia

disordered movement

hyperkinesia

involuntary, spontaneous movement; includes tics, chorea, athetosis, and ballismus

hypokinesia

lack of spontaneous movements; slowing of voluntary movement; includes rigidity and bradykinesia

rigidity

resistance to externally imposed (manipulated) joint movements

bradykinesia

slowness of initiation of voluntary movement with a progressive reduction in speed and range of repetitive actions

tic

sudden, involuntary, and repetitive motor movement that is not rhythmic and involves discrete muscle groups; usually associated with awareness of an urge to perform the movement; occur with intervening periods of normal movement

chorea

continuous sequence of one or more discrete involuntary movements or movement fragments; often rapid, random and unpredictable

athetosis

continuous, involuntary writhing movements; smooth, nonrhythmic movements that appear random and are not composed of any recognizable sub-movements; mainly involve distal extremities, but can occur in other body parts

ballismus

nonrhythmic, rapid, nonsuppressible, and violent movements; most often seen in one half of the body, often within an isolated body part