Block 7 Flashcards
What is the problem with pain definitions?
context dependent nature
2 categories of operational definitions of pain
noxious and objectionable
a stimulus that causes tissue damage
noxious stimuli
a stimulus that does not cause tissue damage, but is still painful/unpleasant
objectionable stimuli
pleasure circuit that uses a catecholamine
dopamine
pleasure circuit that uses a class of peptide transmitters
endogenous opiates
a dense fiber tract (collection of axons projecting from hindbrain to forebrain), produces the highest rate of self-stimulation at lower electrical intensities
medial forebrain bundle
6 areas that the medial forebrain bundle projects to
cingulate gyrus, septum, amygdala, olfactory and frontal neocortex, parts of basal ganglia, and nucleus accumbens
cells of origin for the medial forebrain bundle contain __ as their neurotransmitter
dopamine
2 dopamine containing cell bodies
substantia nigra and ventral tegmentum
DA projection from the substantia nigra, projects to the striatum
nigrostriatal pathway
nigrostriatal pathway shows the relationship between dopamine and __
motor behavior
DA projection from the ventral tegmentum to the neocortex
mesocortical pathway
DA projection from the VTA to the limbic system/nucleus accumbens
mesolimbic pathway
the mesocortical and mesolimbic pathways show the strong link between dopamine and __
reward
VTA sends DA projections via MFB to the ___
nucleus accumbens
injections of a dopamine __ into the NAc block the rewarding quality of MFB stimulation
antagonist
__ is a key site in reward mechanisms
nucleus accumbens
injecting a DA __ will make an animal do anything for reward
agonist
two drugs that increase dopamine availability in the synapse
cocaine and amphetamine
two opposing systems that control pain
ascending nociceptor system, descending analgesia system
cause of inflammation
cells release of histamine, bradykinin, prostaglandin, and serotonin
nociception is carried to the spinal cord by small unmyelinated fibers (__) and by small myelinated fibers (__
c-fibers, a-delta fibers
c and a-delta fibers terminate in edges of the __
dorsal horn
peptide located heavily in the dorsal horn of the spinal cord; areas of c-fiber and a-delta fiber termination
substance p
pain insensitivity syndrome in humans is caused by a depletion of spinal __
substance p
reduce levels of substance p cause severe losses in __
nociception
type of second-order nociceptor cells located in the edges of the dorsal horn; receive contacts from both a-delta and c-fibers, and only respond to noxious stimuli
nociceptive specific cells
type of second-order nociceptor cells located deeper in the dorsal horn; receive contacts from a-delta receptors and mechanoreceptors (pressure)
wide dynamic range cells
electrical stimulation of a number of areas within the __ will render an animal analgesic, or unresponsive to noxious stimuli
brainstem
2 brainstem structures involved in analgesia
periaqueductal gray region, and raphe nucleus
what mediates analgesia?
endogenous opiate-like molecules
located in pituitary and brain, comprised of 31 amino acids
endorphins
located in spinal cord and adrenal gland, smaller pentapeptides (5 amino acids)
enkephalins
enkephalins co-localize with ___ (nociceptors) in the dorsal horn of the spinal cord
substance p
enkephalins produce pain control presynaptically by inhibiting the release of __ by first-order nociceptor cells
substance p
pain control is called
analgesia
opioids produce spinal analgesia by ___
presynaptic inhibition
opioid signal inhibits __ flux into presynaptic terminal, which deactivates __ potential, and inhibits release of __
calcium; presynaptic; substance p
__ is contained in presynaptic terminals in the periaqueductal gray region; when it is released onto PAG neurons it causes analgesia
beta-endorphin
part of stress-induced analgesia is __ mediated
opioid
what causes a runner’s high?
release of endorphins and enkephalins
what causes the learned helplessness model (animals)?
ACTH (stress hormone), cholecystokinin, and other neuropeptides
