Neuroscience Final Flashcards
Info post test 2
Cerebellum Structure
-two hemispheres connected by midline vermis
-critical for movement learning and timing
-vast majority of neurons in brain
-only 10% of brain volume (concentrated)
-tightly folded structures
-doesn’t send direct projections to spinal cord (indirect modification)
-anatomical but not functional control
Sectors of cerebellum
-medial (spinocerebellum)
-lateral (cerebrocerebellum)
-flocculonodular
Medial (spinocerebellum):
-receives proprioceptive inputs modulating body and limb movements
-prediction control
-timing (cerebellum is central clock in CNS)
Lateral (cerebrocerebellum):
-receives input from cortex (parietal lobe)
-planning movement
-lesions cause hypometria and hypermetria
Flocculonodular lobe:
-connections to vestibular nuclei and supports head and eye movement
-balance and postural control
-lesions cause impaired balance and posture
Cerebral atrophy
-neurodegenerative disease causing atrophy
-demonstrate ataxia of gait
-struggling with timing
-dysmetria (hyper or hypo) predictive control
Hypermetria
overshoot target
Hypometria
undershoot target
Learning new motor skills
-maintained with neural network of cerebellum
-when you start to learn something new (cognitive) becomes more procedural memory
-neural networks not cognitive in nature
Cerebellar lesions
-mirror tracing task
-becomes much quicker and accurate later in trials (for control)
-speed and accuracy provide proof of motor memory
-performance on 1 and 10 mirrors performance on 41 to 50 (lesion group)
-takes longer and less accurate, not learning the task showing impairment
HM
-no difficulty learning new motor tasks
-semantic and episodic memory issues
Movement timing (tennis ball on target on wall)
-control and lesion groups
-low speed and high speed movements
-less variable error in control
-all over the place high variable error for lesion
-lesion: variable release point, control: consistent release
-central clock within cerebellum, timing of agonist and antagonist muscle contractions
Rebecca Spencer and Howard Zelaznik (finger tapping metronome)
-different frequencies of metronome
-take away metronome and continue tapping at same pace
-control: no problem, lesion: problems about 5s after (off beat) couldn’t keep up
-cerebellum important for timing
-explains dysmetria and gait ataxia
Challenges with stuttering
-might have soft cerebellar deficit
-might not have configuration for central clock
-finger tapping with stutter vs no stutter
-metronome variable timing
-change in the wiring in cerebellum
Descending Motor Pathway - Pyramidal Tract
-brinkman and kypers study (basic understanding of movement and goal directed movement)
-1 million myelinated fibers (fast conductions) large fibers (also fast)
-fast response to things like slipping
-majority of fibers originate in M1, SMA, PMA and parietal lobe
-fine digit control (size and myelination of descending motor pathway
-innervate facial musculature and oculomotor muscles
-intrinsic musculature
Corticobulbar tract of fibers
-pyramids of brain
-corticobulbar terminate above pyramids
-corticospinal fibers terminate below pyramids
-connection occurs superior to pyramids
-oculomotor control
-rostral component (innervates upper facial muscles, bilaterally)
-caudal (lower facial musculature, contralateral)
-corticonuclear pathway/corticobulbar
Corticobular Injury
-lower: bells palsy
-upper: stroke
-selective paralysis in contralateral lower facial muscles
-can innervate multiple muscle groups (coordinated smooth movement)
Lateral corticospinal tract
-majority originate in M1
-cross over at pyramids (contralateral control)
-control muscles on opposite side of body
-type of upper motor neurons that innervate intrinsic muscles (fine motor control)
-large majority of monosynaptic connections (directly synapsing with a lower motor neuron, direct control over muscle for movement
-precision grip, digits move independent, language
-one of most important features
Descending Motor Pathways, Spinal Connections and Exercise
-alpha motor neurons can have different typologies
-fast: largest axons in spinal cord (large diameter fiber neurons, heavily myelinated, 100m/s)
-slow: less myelinated, 40-60m/s
-types interface with different muscle fiber types
-degree of plasticity in spinal cord with motor unit composition (detraining), maybe fast to slow and opposite
-dark because of high concentration of mitochondria and hemoglobin (slow)
-light (fast twitch)
High variability of motor neuron types based on individual
-sprinter: motor unit asymmetry (80 fast to 20 slow)
-marathoner: inverse (primarily slow)
-average person: 50 50
-couch potato: more fast than slow
-spinal injury: more fast than slow (don’t move for a long time)
