neuro lec 4 Flashcards
(51 cards)
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
what are the parts of the cerebellum (3)? which part of the brain is the cerebellum part of?
- vermis (worm): separates cerebellar hemispheres
- primary fissure
- horizontal fissure
- metencephalon
what are the 3 cerebellar nuclei? describe the function of each + what happens when there is a lesion.
- fastigial nucleus: vestbiular, motor, gait, and posture. lesions = loss of balance and involuntary movements.
- interpositus nucleus: motor coordinating agonist and antagonist muscles. lesions = tremor.
- dentate nucleus: fine motor control of voluntary movements. lesions = ataxia.
what are the 3 cerebellar peduncles? what kind of input is each related to?
- superior: output from Cb.
- middle: input to Cb via pons (movement + cognition).
- inferior: input to Cb via pons (vestibular).
unlike the cerebral cortex, the cerebellum receives input from, and controls output to, the____ side of the body, and damage to the cerebellum therefore results in deficits to the ____ side of the body.
ipsilateral
ipsilateral
