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Behavioral Neuroscience Unit 4
Terms in this set (33)
What are flexors/extensors? Synergists/antagonists, and tendons?
Flexors: draws two body parts together
Extensors: moves body parts away
Synergists: a muscle that acts together with
Antagonists: muscle that counteracts the effect of another muscle
Tendons: tissue that connects muscle to bone
What do the terms efferent and afferent mean?
Efferent: bring info from brain to muscle
Afferent: bring info from muscle to brain
What is the difference between closed and open loop control mechanisms? Give examples of each.
Closed: maximize accuracy; complete feedback loop; driving a car
Open: maximize speed; no feedback; pitcher throwing a ball or being able to type name without looking
Is the innervation ratio of all motor units the same? Explain.
No, more precise movements have smaller ratios; ex: eye movement is 1:3
What neurotransmitter is used to stimulate muscle fibers and cause them to contract? How do EPSPs at the neuromuscular junction differ from those in the brain?
Don't cause postsyn. AP but rather contraction of the muscle. Usually, every AP that reaches causes contraction.
What is the difference between an alpha motor neuron and a gamma motor neuron? Think about what is innervated by each and the functional role of each.
Alpha: controls main contractile (extrafusal) FIBERS in muscle; do work
Gamma: controls main contractile (intrafusal) TISSUE in muscle spindle; controls tension
What are the three sources of input (names of the neurons) to alpha motor neurons?
Sensory cells, upper motor neurons, spinal interneurons
How is movement affected in individuals with amyotropic lateral sclerosis and myasthenia gravis? What specifically is affected in each disease and what are the symptoms?
ALS: death of motor neurons; paralysis and death
MG: autoimmune disease that attacks ACh receptos; messes with NMJ; weakness of muscles
What is another name for muscle spindle? Where is it? What sense does it provide to us? What type of motor information do muscle spindles provide? What is the name of the axon that innervates muscle spindles? What does it do?
Parallel to muscle
Sends AP to CNS when muscle is stretched
Sensory neurons (afferent/efferent)
Detect changes in muscle STRETCH
What is the golgi tendon organ, and what kind of proprioceptive information does it monitor? How is the golgi tendon organ different from the muscle spindle?
Receptors located on the tendons that sends AP to the CNS reporting muscle tension
It responds to tension not stretching
For the stretch reflex, what is the stimulus that triggers the stretch reflex and identify the structures, neurons, and axons involved.
Contraction that results when a muscle stretches
Afferents from muscle spindle are excited -> monosynaptic connection to motor neurons, excite -> stimulate muscle to oppose stretch
What is the myotatic reflex (give one example)? What kind of stimulus causes it and why is it called monosynaptic? How does stretching the tendon below your kneecap cause you to kick? What role does reciprocal inhibition play in the myotatic reflex?
Knee jerk reflex
When muscle is stretched, sensory neurons fire more; only innervated by one nerve
Stretches quadricep -> muscle spindles are excited -> motor neurons send AP to target muscle
Contraction of quad causes other muscle to expand
What cells do spinal interneurons receive information from? How do spinal interneurons create smooth movement? (basic, don't need all the details)
Relay signals between afferent and efferent neurons
send signals to alpha neurons which regulate movement in muscles
What is reciprocal inhibition? How is it useful?
contraction of one muscle causes other to expand
avoids damage of opposite muscle to contraction
What are the three motor cortical areas in the human brain? What functions does each serve?
Primary motor cortex: movement
Premotor cortex: guidance of muscles
Supplementary motor cortex: planning movements
Describe the pyramidal system and primary motor cortex. Which lobe is M1 in? Why is the pyramidal system also called the corticospinal tract (remember about breaking apart words that name neural structures)?
M1 is in the frontal lobe
Originate in cortex and extend to spine
Do neurons in M1 code muscle contraction or the direction of movement? Describe the evidence.
Tests on monkeys show that any one cell has a directional preference
What are motor neurons, where do they live and what stimuli do they respond to?
What: trigger muscle contractions
Where: spinal cord
How does the brain plan motor actions?
Primary and Secondary motor cortex
Describe the properties of cortical plasticity. What are some examples of this?
Increase in the area of brain specialized for a specific area
ex: musicians have larger area expanded cortical representations
What specific regions make up the basal ganglia? What is the general purpose of the BG?
Caudate, globus pallidus, and putamen
What does the cerebellum appear to do?
learning of new motor programs, smooth movement
With which cortical regions does activity in the cerebellum and BG correlate?
Cerebellum = supplementary motor area (monitor to produce smooth movement)
BG = primary motor cortex (initiate/terminate movements)
What is Parkinson's disease? What are its symptoms (use some fancy words), and what kind of cell death is a hallmark?
Basal ganglia doesn't work; absence of muscle movement
degeneration of dopamenergic cells in substantia negra
What is Huntington's disease? What are its symptoms and where is cell death observed?
Increase in movement
Jerky, spontaneous movement; lack of cordination
degredation of globus pallidus
What qualities of touch (or different somatic sensations) can the somatosensory system detect?
pain, heat cold (free nerve endings)
What role does attention play in sensory processing? Which brain area(s) appears important for attention?
Where we focus on one or more specific stimuli
Cingulate cortex and parietal cortex
The spinal cord has a particular organization. What sort of information is carried in the dorsal horns? What about the ventral horns?
Dorsal(lateral): fine touch, voluntary movement
Ventral horns: skeletal muscles, touch
How is the body surface represented in the brain? Which lobe is primary somatosensory cortex in? What's a funny name for this? What areas of skin are more represented than others? Why?
homunculus (weird looking guy)
Hands, face; more precise motion
What information typically descends from the cortex to the periphery? What information ascends?
Describe the dorsal column pathway and the Spinothalamic pathway. What kind of sensory information does each carry? Where do they synapse? Where do they cross the midline? Where do they end up?
Dorsal: touch; synapse at dorsal column nuclei (medulla); cross midline at thalamus and go to primary somatosensory cortex
Spinothalamic: pain and temp; synapse at dorsal horn of spinal cord; cross in spinal cord and go to thalamus
What chemicals mediate pain? (5) How might a placebo drug mediate pain?
neuropeptides, serotonin, histamine, enzymes and hormones
Placebo relieves pain by causing the release of endogenous opioids
Explain the reverse myotonic reflex
Receptors on golgi tendon sense that there is too much tension -> 1b neurons send a signal(interneuron) -> synapse on alpha motor neurons and inhibit them (polysynaptic)
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