Initiation of Movement:
- Frontal lobes
- Prefrontal::planning of movement
- Premotor::organize motor sequences
- Primary::produce specific movements
- Support w/neuroimaging - sensation and motor bands, supporting motor areas
Components:
- Upper and lower motor neurons::movement of Actin and Myosin along the muscle fibers, causing contraction of muscle
- Neuromuscular junction and ACh
- Decassation of the medulla (just like somatosensory cortex)
Corticospinal Tracts:
- Topographic map associated w/the spinal cord
- Lateral corticospinal tract::moves limbs and digits
- Ventral corticospinal tract::moves muscles of midline of the body
- Interneurons project to motor neurons - motor neurons project to muscles of the body
The Spinal Cord:
- Divided into different segments
- Cervical region::hands and arms
- Lumbar::legs
- Thoracic::trunk/organs
- Quadriplegia::leg and arm paralysis above C4
- Paraplegia::leg paralysis; damage to thoracic and lumbar segments
- Paralysis patients a real driving force behind stem cell work
- Stem cells = dirty word in neuroscience
- Pluripotent stem cells
- Adult cells are collected from the patient and reprogrammed and derived to the affected cell types (endothelial, muscle, etc)
The Brainstem and Species-Typical Movement:
- Coding of species-specific unconscious behaviors
- Derived from the brainstem
- Ex: flailing before a fall, chest puff after being threatened, facial expressions
Mirror Neurons:
- Active during preparation of a movement; active while watching someone else perform a similar movement
- Empathize with emotions that someone else is having
- May be important for understanding, identifying, and imitating other people; may be involved in social behaviors
- Unknown whether they cause or result from social behavior
- Located in the parietal lobes and the dorsal lateral prefrontal cortex
The Basal Ganglia:
- Allows us to adjust force of our movements
- Inputs - motor cortex, premotor cortex, prefrontal cortex, substantia nigra
- Outputs - motor cortex, substantia nigra
- Caudate/putamen::input from cortex, output to globus pallidus
- Globus pallidus::connect to and inhibits the thalamus
- Basal ganglia selects a movement to make by ceasing to inhibit it
Damage to the Basal Ganglia:
- Caudate/putamen
- Hyperkinetic::too much movement
- Huntington’s Chorea::uncontrollable flailing motions; doesn’t appear until your 40s; always fatal about 7-10 years after diagnosis
- Tourette’s Syndrome::bodily tics
- Substantia nigra
- Hypokinetic::too little movement
- Parkinson’s Disease::inability to initiate movement over time
Cerebellum:
- Essential for acquiring and maintaining motor skills - practice and precision
- About 20% of brain volume and 1/2 of all neurons
- Damage
- Midline::balance, eye movement, upright posture, walking
- Lateral::arm, hand, finger movements
- Movement control
- Timing of movements (metronome and tapping)
- Movement accuracy (throwing darts)
Repair, Regeneration, and Recovery:
- What is recovery?
- Complete return of function vs marked improvement in function vs degree of improvement
- Question of compensation - brain damage usually improved
- Factors likely to influence recovery in CNS
- Severity, #, spacing of insults
- Age at time of insult
- Extent to which function can be taken over by another
- Extent/quality of rehabilitation
- Difference in brain structure
- Overall brain integrity
- Motivation/emotional factors
- Peripheral nerve regeneration
- Henry Head
- Superficial radial nerve and external cutaneous nerve
- Protopathic vs. Epicritic
- Hot and cold - 7wks
- Light touch - 1yr
- Schwann cells will come into damage area and guide axon (like orange barrels on highway)
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