Diencephalon and Basal Ganglia Flashcards
What does subcortical mean?
beneath the cerebral cortex
What are the major subcortical structures of the brain?
- diencephalon
- basal ganglia
What color brain matter is the diencephalon?
nuclei gray matter
What are the 4 parts of the diencephalon?
- epithalamus
- thalamus
- subthalamus
- hypothalamus
What are the 5 parts of the basal ganglia?
- caudate
- putamen
- globus pallidus
- subthalamic nucleus
- substantia nigra
What is the epithalamus and what is its role?
- single midline structure also called the pineal gland
- secretes melatonin (sleep-wake cycle)
- has no neural output
What is the thalamus and what is its role?
large bilateral structure that serves as a relay and association center
What is the role of the hypothalamus?
mediate complex functions
What are the implications of a stroke in the thalamus?
a small stroke in the thalamus can have big effects due to high specificity
What is the role of the ventral anterior and ventral lateral nuclei of the thalamus?
- motor nuclei (LCST and ACST)
What is the role of the ventral posterolateral nucleus of the thalamus?
sensory relay nucleus for body
What is the role of the ventral posteromedial nucleus of the thalamus?
sensory relay nucleus for the face
What is the role of medial geniculate body nucleus of the thalamus?
relay center for auditory stimuli from CN VIII
What is the role of the lateral geniculate body nucleus of the thalamus?
thalamic relay for CN II
What is the significance of the projections to the thalamus?
specific input goes to the specific area of the cerebral cortex
What vessel provides blood supply to the thalamus?
posterior cerebral artery
What is thalamic pain syndrome or thalamic syndrome?
occlusions of PCA causing contralateral to lesion symptoms of hemianesthesia, ataxia, excruciating neurogenic pain
What is the role of the hypothalamus and what is the significance of damage to this structure?
- regulates endocrine function
- chief effector of limbic system, so if damaged major effects to emotion, memory, and drive related behavior
What vessels supply blood to the hypothalamus?
ACA, Ant comm, PCA, Post comm
What are the endocrine functions of the hypothalamus?
- body temp regulation
- sleep wake cycle
- emotional and behavioral function
What is the effect of diabetes on the hypothalamus?
causes damage to hypothalamus, affecting thirst, hunger, body temp, sleep-wake cycle
What is the sub thalamus?
wedge shaped transition between thalamus and midbrain
What is significant about the subthalamic nucleus?
nucleus of the subthalamus and basal ganglia
What vessel supplies blood to the sub thalamus?
PCA
What happens if the subthalamus does not get blood supply?
hemiballismus: involuntary movement of half of the body
What basal ganglia nuclei make up the striatum?
caudate and putamen (divided by internal capsule)
What basal ganglia nuclei make up the lentiform?
- putamen and globus pallidus
How does disinhibition work?
VA and VL nuclei of the thalamus are excitatory, they are tonically inhibited by globus pallidus, in order for the thalamus (VA/VL) to excite the cortex the other basal ganglia must inhibit GP to disinhibit VA and VL
in order for movement, must be disinhibition
What are the basic concepts of the direct pathway of the basal ganglia?
facilitates movement by disinhibiting VA/VL
What is the basic concept of the indirect pathway of the basal ganglia?
decreases movement initiation (involuntary) by inhibiting VA/VL pathway
Do the direct and indirect pathway work against each other or in tandem?
truly work together to control movement
What is the pathway of the direct pathway?
cerebral cortex > excites striatum > striatum inhibits globus pallidus > thalamus disinhibits > activity facilitated
What is the pathway of the indirect pathway?
cerebral cortex > excites striatum > striatum inhibits globus pallidus externus (stops inhibition of subthalamic nucleus) > thalamus inhibited > activity suppressed
What is the role of the globus pallidus and subthalamic nucleus in the direct and indirect pathway?
globus pallidus: bouncer, stops thalamus from activating motion
subthalamic nucleus: enhances GP ability to inhibit thalamus
What is the role of dopamine in movement?
net effect of dopamine is movement
effect of loss of dopamine is decreased movement
What are the parallel channels?
motor, oculomotor, prefrontal, limbic
What is the significance of Parkinson’s disease and why does it happen?
- degenerative disease that causes neuron death that causes the loss of dopaminergic projections
- loss in dopamine, loss of movement
What basal ganglia produces dopamine?
substantia nigra: pigment cells
PD patients have no pigment cells
What are the cardinal signs of Parkinson’s disease?
- Bradykinesia: slow movement initiation
- difficulties with balance
- rigidity
- resting tremor (direct and indirect pathways)
- decreased dopamine, limited movement
What are the nonmotor impairments of Parkinson’s disease?
cognitive decline, autonomic changes, pain, fatigue
What is L-DOPA and why is it significant to PT practice?
- dopamine replacement that can cross blood brain barrier
- on/off phenomena makes it important that we treat while patient is on an “on” cycle
- long term dyskinesia: long term use decreases effectiveness
What are some surgical interventions that can be used on patients with PD?
- deep brain stimulation
- pallidotomy (removal of GP)
- ventrolateral thalamotomy
What is Huntington’s Disease and its significance?
- inherited neurodegenerative disease
- gross atrophy of striatum (caudate and putamen)
- loss of GABAergic neurons which decreases inhibition of basal ganglia which causes involuntary movements
How is Huntington’s Disease characterized?
- motor changes: increase in involuntary movement
- cognitive decline leading to dementia
- psychiatric disorders
What is the medical and physical management of HD?
dopmine antagonists: decrease dopamine, decrease involuntary movement
deep brain stimulation
removal of globus pallidus internus
How would you conduct and exam and intervention for HD?
- united Huntington’s disease rating scale
- assessment of activities
- tests of strength, tone, gait
What is hemiballismus and its significance?
- severe form of dyskinesia
- wild un-patterned movement of entire extremity
- results in under activity of indirect pathway
What are the likely causes of OCD and Tourettes?
- problems in both basal ganglia synaptic connectivity and neurotransmission
