neuro lec 4 Flashcards
what are the 3 parts of the basal ganglia?
- caudate nucleus
- putamen
- globus palidus
what is the caudate nucleus + putamen called? what about putamen + globus pallidus?
- caudate nucleus + putamen = “striatum”
- putamen + globus pallidus = “lenticular nucleus”
functions of the basal ganglia? (4)
- facilitating desired movements and Inhibiting competing/undesired movements.
- cognitive functions.
- timing of automatic movements.
- contains motor homunculus in motor regions.
if the basal ganglia is a facilitator, which part of the brain is the initiator?
superior motor area
name 3 disorders of the basal ganglia
- parkinson’s disease (difficulty initiating movements).
- huntington’s disease (difficulty inhibiting involuntary movements).
- tourette syndrome (inhibiting undesired movements, tics, verbal, and thoughts)
describe the DIRECT pathway of the basal ganglia-thalamic-cortical system (4)
- the thalamus excites the cortex (more motor activity).
- GPint inhibits the thalamus.
- striatum inhibits the GPint.
- net result: more excitation of the cortex.
describe the INDIRECT pathway of the basal ganglia-thalamic-cortical system (4)
- subthalamic neurons are firing, increasing GPint neurons.
- net result: inhibition on cortex.
- firing of GPext neurons inhibits the subthalamic neurons, making the GPint neurons less active.
- net result: inhibiting the thalamus.
which pathway does parkinson’s disease affect? what about huntington’s disease?
- parkinson’s: direct pathway (net result of inhibition = difficulty initiating movements, slowness…)
- huntington’s: indirect pathway (net result = difficulty inhibiting movements…)
what are the 3 nuclei related to the basal ganglia?
- substantia nigra
- subthalamic nucleus
- nucleus accumbens
where is the substantia nigra located? what does it produce? what does a loss of these cells result in?
- midbrain
- dopamine
- parkinson’s disease
T or F: the nigrostriatal pathway only excites the direct pathway.
false – has the dual effect of exciting the direct pathway while simultaneously inhibiting the indirect pathway.
what brain part is the subthalamic nucleus part of? what does it play a role in?
- diencephalon
- movement regulation
what is deep brain stimulation? who is it used on? what are its benefits?
- pulse generator sends impulses to subthalamic nucleus
- medically intractable parkinson’s patients
- may alleviate side effects of medication + increase medication tolerance
where is the nucleus accumbens? what does it mediate?
- between caudate and putamen
- mediates goal-directed behaviour and plays a role in addiction
what are the 5 subcortical tracts?
- superior longitudinal fasciculus
- arcuate fasciculus (part of SLF?)
- corpus callosum
- internal capsule
- corona radiata
what is the function of the arcuate fasciculus?
- connects broca’s with wernicke’s area
- basically language processing
what is the function of the corpus callosum? what are its 2 main parts? by what age is it developed?
- integrates info between two hemispheres
- forceps major (“splenum” near occipital lobe) and forceps minor (“genu” near frontal lobe)
- complete by age 4 but growth continues until 30
what is the function of the internal capsule? is it afferent or efferent?
- separates caudate from lenticular nucleus and connects cortex with subcortical structures/brain stem/spinal cord
- bidirectional (efferent AND afferent)
what is the corona radiata?
- fibers of internal capsule radiate to various parts of the cerebral cortex and BG
why is the cerebellum called “little brain”?
bc it has its own cortex and subcortical structures