hormones and cognition Flashcards
flashbulb memort
vivid memories of important, stressful events
not a separate memory function, but a class of memories that are:
a) more FREQUENTLY REHEARSED
b) more STRONGLY ENCODED
positive, yet stressful, events like weddings, births, lottery winnings are also remembered with great clarity
type of memory that operates without a NS
vaccines
human immune system can recognize something it has seen before and enact a response
all memory systems shared which abilities?
abilities to…
- enter info into storage (acquisition and consolidation)
- retain info
- retrieve info from storage
learning requires what to happen to info?
- input
- storage
- retrieval
why are effects of hormones on learning/memory based on task performance/observed behaviour?
because hard to measure learning directly
can only measure behaviour directly and quantitatively
BUT there are other ways by which hormones affect performance
hormones and memory: what steps can hormones affect?
all three of the INPUT, STORAGE and RETRIEVAL stages
psychological components of learning/memory
- motivation
- attention
- arousal
they all interact and affect one another
psychological components of memory can’t be directly measured, so…
only performance on tests designed to assess them can be measured
hormones and psychological components of memory
hormones = involved in arousal, motivation and attention
(and sensation, perception, emotion…)
hormones can affect the ANXIETY LEVEL independently from arousal during acquisition or memory testing
what can hormones affect independently from arousal?
anxiety level during acquisition or memory testing
one of the few laws of psychology
inverted U-shaped function of arousal
optimal performance on a learning task occurs at MODERATE AROUSAL LEVELS
if arousal is TOO LOW or TOO HIGH, learning is adversely affected
learning/performance: because hormones are involved in arousal…
they can have affects on learning/performance
learning
process of ADAPTIVE CHANGE IN BEHAVIOUR in response to EXPERIENCE
memory
encoding, storage and retrieval (or forgetting) of information about past experience
necessary for learning
hormones can affect any one or all of these stages of learning/memory
associative learning
learning about relationships through repeated experience
aka conditioning
sensitization
type of non-associative learning
stimulus that originally provoked little/no response begins to evoke a STRONGER response
after several presentations or a single intense presentation
habituation
type of associative learning
learning NOT TO RESPOND after repeated exposure to a stimulus
decrease in response to stimulus
results from reduction in amount of neurotransmitters released into the synapses
non associative learning
learning that doesn’t require pairing or stimuli association
altered response upon only one presentation
ie. sensitization
classical conditioning
response that was originally elicited by one stimulus can now be elicited by another stimulus that originally had no effect
learning represents the formation of an ASSOCIATION (pairing) between the two stimuli
Pavlovian conditioning
classical conditioning
operant learning
when animal performs an action in course of APPETITIVE or SEARCHING behaviour
frequently by accident
which is REINFORCED/REWARDED
often this single incident doesn’t lead to direct association of the action (operant) with its result (reinforcement)
but if act is performed several times, by CHOICE, and is reinforced EACH TIME…
association gradually builds
skinner box
used to measure instrumental learning/operant conditioning tasks
facilitates assessment of the ability of an animal to form an association between the BEHAVIOUR and its OUTCOME
active avoidance
form of associative learning
situation where animal must DO SOMETHING to AVOID a noxious situation
ie. mouse has to move to one side of Skinner box to avoid a shock
passive avoidance
form of associative learning
individual must SUPPRESS SOME BEHAVIOUR to that would otherwise be exhibited
ie. mice like the dark. mouse is placed in bright part of box, next to dark area. when it goes to dark part, it gets a foot shock. must go back to bright area to escape the sock
passive avoidance mouse skinner box: measure of strength of its memory
length of time the mouse remains in the lighted compartment
short term memory persists how long?
seconds to minutes
best way to move items from short to LTM
rehearsal
long term memory lasts how long?
days, weeks, years
no upper limit in capacity or retention
LTM splits into…
explicit (declarative) and implicit (non-declarative)
explicit splits into: semantic and episodic
implicit splits into: priming, conditioning, skill learning
working memory
similar to declarative and STM because it typically involves STM for info that changes on a regular basis
ie. remembering a phone number before you find paper to write it down on
reference memory
refers to associations/discriminations requiring REPETITIOUS LEARNING
ie. learning the rules
ie. putting keys in the same spot every time you get home
spatial memory
subcategory of memory that encodes info about the ENVIRONMENT and its ORIENTATION
3 main hormones that affect learning and memory
epinephrine
insulin
glucocorticoids
why don’t we know exactly how epinephrine works in the brain to store memory?
because it’s a polar molecule, so it doesn’t cross the blood brain barrier
epinephrine is released when…
learning occurs
generally enhances memory
u shaped function and epinephrine
u shaped function applies to epinephrine levels too
low and high blood levels of epinephrine impair memory
MODERATE levels ENHANCE memory
Yerkes-Dodson curve
u-shaped arousal curve
memory enhancing effects of norepinephrine depend on…
- dose
- timing
ie. animals perform better in avoidance situations after receiving a MODERATE rather than a mild foot shock
epinephrine potentiates…
the effects of the noxious stimuli used to train animals in active avoidance tasks
this is supported by the fact that epinephrine is released in response to stressful events
optimal epinephrine level for avoidance memory enhancement in rats
1500 pg/ml (in blood)
this level is observed in rats that show optimal performance in avoidance tasks
if mild foot shock produces blood epinephrine levels of 1000 pg/ml and this shock is paired…
with an INJECTION that raises epinephrine levels another 500 pg/ml…
then the exogenous and endogenous sum together…
and the animal exhibits OPTIMAL LEARNING
when is the best time to administer epinephrine?
immediately after training
if treatment comes BEFORE training or after SUBSTANTIAL TIME PERIOD has elapsed since training, it ISN’T EFFECTIVE in enhancing memory
temporal constraints on effectiveness of norepinephrine are consistent with…
hypothesis that epinephrine influences memory by potentiating the effects of noxious events
maybe because this time period is when memory is being consolidated
most effective timing of epinephrine administration in the rat avoidance task
injections are most effective in enhancing memory if given 1 minute after training
how does epinephrine enhance memory? background
doesn’t cross brain barrier - polar molecule
produced by very few neurons in brain as NT
and memory for passive/active avoidance tasks definitely resides in the brain
how can epinephrine secreted by adrenal glands affect learning and memory processes if it can’t get to neurons in the brain?
2 HYPOTHESES
how does epinephrine enhance memory? 2 hypotheses
- epinephrine activates PERIPHERAL RECEPTORS that directly influence brain function
- epinephrine affects memory via effets on BLOOD GLUCOSE LEVELS
hypothesis 1: epinephrine works via peripheral receptors
epinephrine modulates memory by activating peripheral receptors that communicate with the CNS
initiated by activation of peripheral BETA-ADRENOCEPTORS located on VAGAL AFFERENTS that project to nucleus of the solitary tract (NTS) in the brain stem
noradrenergic projections originating in NTS INNERVATE FOREBRAIN structures involved in LEARNING and MEMORY, including the amygdala
amygdala, epinephrine and memory
peripheral receptor hypothesis
epinephrine > beta adrenoreceptors > NTS > noradrenergic projections to AMYGDALA (and other forebrain structures)
amygdala historically considered to be involved in emotions
but also involved in LEARNING and MEMORY
