Test 2 terms Flashcards
plasticity
ability of synaptic function to change depending upon antecedent activity
facilitation
rapid increase in amplitude of post-synaptic potentials following a train of stimuli. 2nd EPSP is bigger than the first, etc.
depression
causes neurotransmitter release to decline during sustained synaptic activity. This depletes the pool of releasable vesicles.
augmentation
increase in the amount of transmitter released from the presynaptic terminal lasting a few seconds.
potentiation
increase in the amount of transmitter released from the presynaptic terminal lasting minutes (post tetanic potentiation).
associative learning
formation of associations among stimuli and/or repsonses
classical conditioning
a neutral stimulus (CS - bell) is paired with a stimulus that elicits a response (US - meat powder)
Instrumental (operant) conditioning
an organism learns to associate consequences with its own behavior. delivery of a reinforcing stimulus is contingent upon expression of a designated behavior.
habituation
reduction in a response to a stimulus that is delivered repeatedly
dishabituation
recovery of a habituated response due to presentation of another strong stimulus
sensitization
enhancement of a response produced by presentation of a strong stimulus
L7
motor neuron that synapses with the gill muscle, the site of which habituation appears to occur
L29
interneuron that releases serotonin in response to the head shock. this activates GPCRs that are linked to CAMP production, which activates PKA which phosphorylates and CLOSES K channels. closing K channels decreases K conductance and prolongs the AP and allows more Ca inside.
Long-term potentiation
long lasting enhancement of the strength of stimulated synapses. LTP is input specific, the input only affects the pathway it is associated with. membrane potential of postsynaptic cell determines if LTP will occur. AMPA and NMDA receptors.
long-term depression
persistent weakening of synapses based upon recent patterns of activity
myosin
long coiled tail and globular head which has ATPase activity. Think filament of muscle.
actin
globular, thin filaments of muscle
tropomyosin
rod shaped, interacts with troponin to hide actin
troponin
protein complex that associates with tropomyosin to form a barrier to formation of cross-bridges between actin and myosin. when Ca binds the tropomyosin-troponin complex exposes myosin
t tubules
invagination of membrane into the sarcoplasmic reticulum that conducts the depolarization (EPP) which triggers the release of Ca
tetanus
contraction is sustained without any relaxations
asynchronous recruitment
to maintain tetanic contractions in a muscle, some motor units are contracting while others relax in order to prevent muscle fatigue and failure
gamma motor neurons
neurons that innervate muscle spindles - specialized muscle fibers that sense stretch and help set muscle fiber length
alpha motor neurons
neurons that innervate the striated muscle fibers that generate the force of contraction
size principle
small units are activated by weak synaptic stimulation, large units require greater synaptic stimulation
motor unit
each motor neuron innervates multiple muscle fibers in a single muscle
motor neuron pool
multiple motor neurons innervate a single muscle
gamma bias
basal level of gamma motor neuron activity required to enable muscle spindles to operate at all muscle lengths
golgi tendon organ
these are in series with extrafusal muscle fibers, are innervated by group 1b sensory afferents, relatively insensitive to passive stretch but are very sensitive to muscle contraction. this regulates muscle tension with negative feedback pathway.
nociceptor
pain receptor, initiates the flexion reflex
flexion reflex
withdrawl from a painful stimulus, yet activates the contralateral limb to maintain balance
central pattern generators
local spinal cord circuits that control and coordinate complex motor behaviors, such as locomotion and swimming. involves stance and swing phases.
vestibular complex
receives information from the vestibular system (balance, equilibrium). rapidly adjusts to stabilize posture.
reticular formation
cardiovascular & respiratory control, sensory motor reflexes, eye movements, sleep, arousal, coordination of limb and trunk movements. initiates adjustments to stabilize posture during movement. is modulatory and premotor
homunculus model
shows what a man’s body would look like if each part grew in proportion to the area of the cortex of the brain concerned with its movement.
mirror motor neurons
distinctive class of neurons that discharge both when a monkey executes a motor act and when it observes another individual performing the same or similar motor act.
spinal shock
initial period of hypotonia when spinal interneurons are devoid of descending input (after a few days spinal circuits regain significant function)
Babinski sign
when dragging a pointy object along the bottom of the foot the toes extend and fan out. indicates damage to corticospinal pathway, and is a potential sign of MS
spasticity
increased muscle tone; hyperactive stretch reflexes and clonus (alternating contractions/relaxations in response to muscle stretch)
medium spiny neurons
contained within the corpus striatum (caudate and putamen), receives input from cortex, and outputs to neurons in globus pallidus and substantia nigra (pallidum)
Parkinson’s disease
disease caused by loss of dopaminergic neurons in the substantia nigra. characterized by tremor, slowed motion, rigid muscles, impaired posture and balance, dementia, etc. treated with L-dopa and possibly stem cell therapy
Huntington’s disease
hereditary, progressive disease that is always fatal. appearance characterized by hyperkinesia and chorea, abnormal movements, dementia, personality disorder. caused by genetic mutation int he gene that produces huntingtin which leads to neuronal cell death. can only treat the symptoms.
motor error
the difference between intended and actual movement
Purkinje cells
the only output cells of the cerebellar cortex, all of which are inhibitory. receives input from parallel (from as many as 200,000 granule cells) and climbing fibers
granule cell
most abundant neuron in the brain, about 200,000 are in contact with 1 purkinje cell via parallel fibers
basket cell
has inhibitory input synapse with purkinje cell
golgi cell
receive input from mossy fibers and has inhibitory output on granule cells
stellate cell
modifies purkinje cell dendritic output via an inhibitory synaps
excitatory loop
made up of mossy and climbing fibers that drive activation of neurons in the deep cerebellar nuclei (DCN)
inhibitory loop
purkinje cells respond to excitatory input from the climbing fibers and granule cells and invert this signal onto the deep cerebellar nuclei
climbing fiber
provides input to the purkinje cell, 1:1 ration, may have 1000 synapses with each cell. AP in climbing fiber gives strong EPSP in purkinje cell
mossy fiber
synapses onto granule cells, axons form parallel fibers which contact many purkinje cells
parallel fiber
synapses with purkinje cells, is made up of granule cell fibers
saccades
conjugate eye movements that change the point of foveal fixation
GABAergic
inhibitory synapses that open Cl channels, how outputs from basal ganglia performs inhibition
