30 terms

Basal Ganglia

What does the basal ganglia do?
1) planning,
2) speed,
3) repetition;
4) emotion and motivation associated with movement
What two structures make up the striatum?
the caudate (RED) and the putamen (GREEN)
What two structures make up the lentiform nucleus?
the putamen (PINK EGG on the inside) and globus pallidus (GREY);
the lentiform nucleus kind of looks like a pair of testicles on each side.
What does the striatum do?
it is the the receiving portion of the basal ganglia; Receives excitatory input from the
1) cortex,
2) thalamus,
3) substantia nigra.
What does the putamen do?
receives organized inputs from
1) the primary motor cortex
2) somatosensory cortex
What does the caudate nucleus do?
receives info from association cortex, regions that are concerned with
1) motor control and
2) some mental function
What is the most important dopaminergic pathway?
the nigrostriatal pathway; it modifies responses of striatal neurons; the rate limiting step, without it, you will produce Parkinsons Sx
What proportion of dopaminergic cells does a person have to lose before Sx appear?
about 80%
What causes Parkinsons?
loss of dopamine in the striatum due to the death of substantia nigra neurons
What are Sx of Parkinsons?
1) akinesia
2) bradykinesia
3) lack of facial movements
4) rigidity
5) resting tremor
T/F In a Parkinsons pt, they often shuffle because they cannot flex their knees, ankles, or hips.
T/F Parkinsons is the actually cause of death
False. The pt. usually dies from choking or from pneumonia
What causes Huntington's disease?
loss of GABA neurons in the striatum and frontal lobe of the cortex
What are Sx of Huntingtons (chorea)?
1) hyperkinesia;
2) rapid, jerky involuntary movements of face, arms, and legs;
3) rapid mental decline d/t to frontal cortex deterioration
What is Athetosis?
writhing, wormlike movements
What is Hemiballismus?
wild, flailing movements of arms and legs due to a lesion in the subthalamic nucleus
What is Tourette's?
Dopamine related condition in the basal ganglia;
involuntary movements or tics;
inappropriate vocalizations;
T/F the basal ganglia are mostly grey matter
What is the order of connections that pass through the cortex and into the basal ganglia?
Cortex-> Basal Ganglia->Thalamus->Cortex->Pyridmidal and Extrapyrimidal Tri.
T/F Lesions of the cerebral cortex can cause paralysis, whereas lesions of the basal ganglia will cause disorganized movement.
T/F The basal ganglia project directly to the spinal cord and brain stem.
False, the basal ganglia DO NOT project directly to the spinal cord or brainstem; they affect movements by influencing motor output of the cortex.
Which basal ganglia are afferent (receives information from other parts of the brain)?
1) Striatum (putamen and caudate)
2) substantia nigra
What is the association area/cortex?
any sensory part of the cortex that is not the somatosensory or motor cortex involved in higher order sensory
T/F Dopaminergic activity can be excitatory or inhibitory.
True. this is why changes in dopamine can cause schizophrenia, tourrettes, or parkinsons.
What are the two major efferent parts of the basal ganglia?
1) substantia nigra
2) globus pallidus
Is the final output from the basal ganglia to the thalamus positive or negative?
It is negative (inhibitory)
T/F Thalamocortical fibers are excitatory (+).
What is the key function of the basal ganglia?
The inhibition and modulation of impulses that begin in the cortex and end up back in the cortex.
What is the subthalamic nucleus?
small internal loop between the globus pallidus and the substantia nigra
What are the connections in the basal ganglia?