Basal Ganglia Flashcards
What is the basal ganglia
- group of gray matter nuclei in cerebrum, diencephalon, & midbrain: (located deep within white matter)
- 5 Nuclei =Caudate, Putamen, Globus Pallidus, Subthalamic Nucleus, Substantia Nigra
- caudate, putamen and globus pallidus are in the cerebrum
- influnce function of movemetn
What are the non motor circuits of the basal ganglia
- Goal directed or executive circuit
- Social-behavioral
- emotion or limbic
Goal Directed or Executive circuit function
- decision-making loop regarding goal directed behavior (Ex: late-yellow light. Brake or accelerate?);
- puts actions in context (Same example-at same light, but not in a hurry, ease gas, etc)
Social Behavioral circuit function
recognition of
- social disapproval,
- self-regulatory control,
- selecting relevant knowledge from irrelevant,
- maintaining attention,
- stimulus-response learning
Emotional or limbic circuit
- links limbic, cognitive, and motor systems
- involved in reward-guided behavior;
- concerned with seeking pleasure;
- involved with facial expression
Motor circuits of the basal ganglia
Oculomotor circuit
motor circuit
Oculomotor circuit
makes decisions about eye movement and spatial attention; initiation of fast eye movement
Motor circuit of basal ganglia
circuit-regulates
- muscle contraction,
- muscle force,
- multi-joint movements,
- sequencing of movements;
- movement selection and action
Caudate nucleus
c-shaped and adjacent to the lateral ventricle
- Head=Anterior
- Body=participates in motor control-part of the oculomotor loop
- Posterior=tail=successful learning
Anterior portion of the caudate nucleus importance
- Executive function/goal directed behavior Loop
- evaluates info for making perceptual decisions, planning, and choosing actions in context
- NOT involved with controlling movement
- active in learning and changes its activity before the cortex when reward contingencies are reversed;
- caudate head is first to learn new contingency=executive function
Lentiform nucleus
- putamen + Globus Pallidus
- coordinates small, precise muscle movements
- Putamen-forms lateral portion of basal ganglia
- Globus pallidus-”pale globe”-many myelinated fibers
What does the putamen do
Putamen receives input from premotor and motor cortex-forms lateral portion of basal ganglia
What does the globus pallidus do
Globus pallidus sends output to motor areas of the cerebral cortex (maintains muscle tone)=motor circuit
What is the striatum
- Caudate + putamen
- contributes to motor control-virtually all inputs to the basal ganglia arrive via striatum
- Join anteriorly=ventral striatum= limbic/Emotion circuit
- role in emotions and motivation
- acts as a link between the limbic, cognitive, and motor system
Neurotransmitters of the basal ganglia
afferent
- glutamate from cerebral cortex=excitatory
- glutamate and ACh from PPN=excitatory
- Serotonin from dorsal raphe nuclei=inhibitory
go into the basal ganglia
Neurotransmitters of the basal ganglia as efferent signals
- Efferent signals leaving the basal ganglia=GABA-inhibits thalamus, PPN, and reticular formation
- Dopamine from substantia nigra to the striatum adjusts signals to output nuclei so these nuclei provide the appropriate level of inhibition to target cells
