KHAN Unit 12: Behavior Flashcards
What is the brainstem divided into? How does it connect into the other parts of the “old brain”?
midbrain
pons
medulla
controls HR, breathing, crossover of nerves
reticular formation: extends up into the thalamus, filters signals, arousal
thalamus: relay station
cerebellum: coordinate voluntary movement, affected by alcohol
1) motor plan (which muscles, what duration)
2) position sense information
3) feedback to cerebrum
What are the four lobes of the brain?
frontal: prefrontal cortex (executive function), motor cortex, Broca’s Area
parietal: somatosensory cortex, spatial processing (orientation)
occipital: vision, “striate cortex”
temporal: auditory processing, Wernicke’s Area
Compare the hemispheres of the brain.
contralateral control: L brain controls R body except smell
dominant hemisphere: left hemisphere for right handed people; language, (Broca’s/Wernicke’s), analytic (logic, math)
non-dominant: emotional tone of language, creativity, music
communicate via corpus callosum
What is the peripheral nervous system made of?
Nerves: contain axons of neurons
- cranial: exit skull (12 pairs)
- spinal: exit spinal cord (31 pairs)
Ganglia: contain soma (cell body) of neurons
What is a motor unit?
lower motor neuron + all the skeletal muscle cells it innervates at the NMJ
- large muscles normally have large motor units
What happens with abnormality of motor units?
weakness
LMN signs = atrophy, fasciculations (twitches), hypotonia (decrease in tone, floppy during relax), hyporeflexia (decrease in muscle stretch reflex)
What is the muscle stretch reflex?
hit patella tendon, stretches quad muscles, muscle spindles stretch, somatosensory neurons carry signal to spinal cord and releases excitatory NT, efferent LMN releases excitatory NT in the muscle, inhibits LMN to hamstring + relaxes, quad muscle contracts
What are the senses of somatosensation?
position, vibration, fine touch: mechanoreceptors; thick myelin sheath, large diameter axon –> fast AP
pain, temperature: nociceptors, thermoreceptors; bare nerve endings; small diameter axon, thin myelin sheath –> slow AP
both of these nerves cross over in the cerebrum
What is grey and white matter?
grey: neuron somas
white: myelinated axons
spinal cord: grey matter inside, white matter outside
brain:
gray matter outside = cortex, gray matter deep inside = nuclei –> BASAL GANGLIA (motor), THALAMUS (relay), HYPOTHALAMUS (endocrine)
white matter inside (tracts: corpus callosum)
Lower motor neurons vs. upper motor neurons
control skeletal muscle cells from spinal cord vs. control LMN from the cortex (higher level control)
corticospinal tract = collection of axons that travel down from one side of the brain to the other side of the spinal cord
- right controls left
- motor functions
corticobulbar tract = UMN axons innervate LMN in the brainstem (cranial nerve nuclei)
- can cross or be same side
- face, head, neck movements
Upper motor neuron dysfunction signs?
hyperreflexia: increase in MSR (lack of inhibition)
clonus: rhythmic contraction of antagonist muscles
hypertonia: increased tone of skeletal muscles
extensor plantar response: scrape the end of foot, toes goes up instead of down
Most common NT.
Glutamate: +
- reticular activating system
GABA: -, brain
Glycine: -, spinal cord
Acetylcholine:
Histamine: hypothalamus
Norepinephrine:
Serotonin:
Dopamine: substantia nigra to striatum, hypothalamus to pituitary
Methods for lesion studies.
- tissue removal
- radio frequency
- neurochemical lesions
- cortical cooling (reversible)
Ways to study the brain.
- CT scans: X-rays
- MRI: detailed structure
- EEG: electrical activity
- MEG: magnetic fields (SQUIDS)
- fMRI: oxygenated blood + structure
- PET: inject radioactive substance
What is behavior?
Coordinated response to the environment (hormones)
