Studied by 2 people
how does LTP work with neurons and synapses, and at hippocampus?
presynaptic neuron and post synaptic, neuron #1 + neuron #2
involved in synaptic plasticity because they're communicating
neuron #1 releases neurotransmitters, neuron #2 is receiving
neuron #2 has a lot of signals, so neuron #2 adds more receptors
since more receptors, neuron #1 sends more info
that's how communication and connections work
long term potentiation that happens at hippocampus, hippocampus will transfer to different areas of neo cortex
different memory systems
autobiographical
semantic
long term potentiation doesn't only happen at hippocampus, happens at different areas of brain
info will transfer to different areas of brain
how long term potentiation will affect different parts of brain hasn't been researched as much as of yet
synaptic consolidation
memories stored by long term potentiation or depression
at neuronal level, how memories work
memories might be stored by changing strength of synapses in brain
synaptic consolidation is believed to lead to system level consolidation
movement of neurons
relates to concept of neuroplasticity
neurons move a lot, neuron links change, brain changes
not usually 2 connected neurons, there is a network
physical properties of neurons play a part
neurons with longer axons can target longer distances and further neurons
Overview of Habituation and Sensitization, learning processses
dual process theory
opponent process theory
different types of perceptual learning
mere exposure
statistical learning
spatial learning
novel object recognition
priming
Recognizing and Responding to Repetition
everything is novel 1st time it happens
even very normal events become mundane only after repeated exposure
when repetition happens, may not keep responding to event even if responded excitedly first time
General Features of Habituation
rat example
e.g. reflex
e.g. response to stimulus
rats first jumped at noise
after 20 ish repetitions, rats stopped reacting to noise, because they were habituated
acoustic startle reflex
defensive response (freezing or jumping) to startling stimulus (loud noise)
orienting response
organism's innate reaction to novel stimulus
e.g. show baby new object like car keys
initial reaction is interest
baby reacts to it, looks intently, trying to figure out what it is
when sees it again and again, orienting response decreases because not new anymore
presenting novel stimulus can lead to recovery of…
recovery of responses after habituated to familiar stimuli
e.g. baby gets used to car keys and becomes bored, then start showing chocolate bar and after a while, show car keys again, baby might be interested in keys again
when presenting keys to baby multiple times, it gets bored
when move car keys and show to baby, may become intrigued again
habituation to one event doesn't cause habituation to every other—
—stimulus that is similar in a sensory way (same sensory modality)
how fast response habituates and how long decrease in responding lasts (duration of habituation) depends on different factors
like how shocking the stimulus
number of times it's experienced
length of time btwn repeated exposures
habituation may last for few minutes or hours (short term) or more than a day (long term)
PTSD, events and sensitization
experience with arousing stimulus leads to stronger response to later stimulus
traumatic experience
anything that incites memory of that event might have greater response than warranted or would be usual
this could lead to avoiding similar stimulus or experiences that somewhat relate to traumatic event
can become sensitive to things that remind of traumatic event
so may have stronger reactions when exposed to similar reminders
start to avoid anything that triggers those memories
long term potentiation at neuronal level can lead to behaviour differences
dishabituation can affect sensitization later on, dual process theory relates
one way that researchers can study sensitization experimentally in humans is by measuring electrodermal activity, this helps because …?
EDA
measure of changes in skin's electrical conductivity
this is caused by fluctuations in activity of peripheral nervous system
wrist sensors can be used that measure EDA
those sensors can help have record of habituation + sensitization process
arousal or sensitization can have physiological response
decrease in response can be habituation, increase means sensitization
e.g. partner snores loudly, used to wake up when snoring loudly, don't wake up anymore due to habituation
e.g. neighbour makes noise late at night, one night u react by yelling and saying to stop --> sensitization
dual process theory
theory that habituation and sensitization are independent or each other but function in parallel
how to predict behaviour that someone will have when similar stimulus can lead to either process
this theory helps with that
used in social psych, etc
2 processes can be independent and also work tgt
both sensitization and habituation processes happen as response to each stimulus presentation
summed combo of both processes determine strength of responding
dual process theory of habituation
stimulus for first time will activate sensory neurons then motor neurons along with state system (similar to system of arousal)
motor neurons will lead to a response
all of these responses (+neurons) will activate state system
during 10 boring repetitions will lead to weaker responses
with 10 arousing repetitions will affect state system because will be aroused again, so other system and neurons will form stronger connections
state system will determine if boring or arousing
ur experience will determine if stimulus is boring or not
e.g. for PTSD, loud noise could be nothing for someone, but for someone with PTSD, it triggers past, so it is not boring or mundance
depends on if state system gets aroused or not
processes work tgt to regulate response u will have
time is a key factor
behaviour is result of summation
in a lot of examples, sensitization is possible because …
habituation has happened, if become habituated, response will be weaker
desensitization
e.g. desensitized to violence
not becoming habituated
but decrease in behaviour and response
distinguishes because habituation will not lead to any arousal
when desensitization, there will be some arousal by state system but not much of response
Opponent Process Theory
similar to dual process theory
assume experienced event leads to 2 independent processes
e.g. 2 emotional processes, pleasant vs less pleasant
overall emotion person experiences in response to event is combined result of independent processes
in this case, there may be one process that is enjoyed, and other is less fun
repeated events have different effects on initial reaction vs rebound reaction
initial responses habituates faster than rebound
Novel Objects: Familiarity Task is Used in Studies + Labs
in this task, organisms's detection of and response to unfamiliar object during exploratory behaviour is used to measure memories of past experiences with those objects
e.g. when rats given 2 objects to explore and after one is taken away and replaced
when rat introduced back to objects, it explores new objects first and more
indicates that it is already familiar with other object
testing does rat become familiarized with novel object
priming
phenomenon where prior exposure to stimulus can improve ability to identify that stimulus later
consciously not recognized stimulus to be familiar
can occur even in absence of feelings of familiarity or recognition that stimulus has been experienced before
could happen even if person doesn't know they rmr it
priming effects could last longer than recognition of past experiences
word-stem completion task to study priming in humans
show participants some stems of words and ask to fill in blanks
in primed experiment, they're more likely to write specific word if they were exposed to it before
they may not even be conscious of it
e.g. stem "MOT__", participants that were primed were more likely to write "motel" if exposed to it before
priming in blue jays
their prey are moths
moths developed patterns that help camouflage in environment
blue jays have been experienced at detecting patterns and identifying moths through subtle difference in patterns
researchers trained blue jays to see different moths with different coloration patterns
blue jays were good at detecting moths than other objects
were faster and accurate at detecting when moth belonged to certain species or category
good at detecting specific characteristics that relate to species
this was unconscious priming
experienced characteristics so many times, that are primed to recognize differences
imprinting vs priming
imprinting is first learning experience
when imitate first behaviour that is seen with object or organism that is first viewed
priming
familiarized with something
even if don't have feeling that it is familiar
unconsciously done
e.g. when u do certain behaviour or take an action
could've been influenced by something u saw that day
if u saw an ad for junk food and later on u crave it or make a decision to get a burger
this means that ur actions were unconsciously influenced
Perceptual Learning
bird learned through perceptual learning
similar to priming
leads to more effective processing on subsequent encounters with stimuli
can happen even if learner is not aware that their sensitivities to perceptual differences are increasing
theories say that different phenomena of habituation, sensitization, and perceptual learning depend on similar learning mechanisms
Spatial Learning + Example
acquisition of info about surroundings
could happen just by being in an environment
unconscious exploring or completing tasks or actions in that place
gain sensory info about the place
when animals explore, they learn more than visual info about object
+ how objects smell, sound
can learn how to get from one place to another
what to expect when visiting certain places
visual cues could help
e.g. when entered UofT, how to get to classroom, used directions or map first time
could have visual clues or aids
recognized that have to turn right when get to bathroom or sign
Spatial Learning by Exploration in Rats
rats were placed in mazes
trained rats to get to food plate
other rats were not trained, untrained rats also got to food plate
they used spatial learning and got there by exploration
used visual + scent clues
related to cognitive maps
Spatial Learning: Use of Landmarks by Wasps
wasps have underground nests
when they leave to find food
wasps fly and look for landmarks and visual cues to rmr where nest was
do orientation flights, fly over nest to recognize it
researchers put objects surrounding the nests
they let wasps and bees habituate to the specific objects that they used to orient to nest
then they changed to objects to something else
when the wasps returned to nests, they would go to the ones with the familiar objects not the actual nest that was in the same place with different landmarks
implicit learning
change in strength of response to stimulus that happens with repeated exposure to stimulus
most basic type of learning
occurs through repetition
sensitization example in class room
e.g. students in both halves of room and wall in between
if there is noise outside
the students not close to door, might be able to ignore noise cuz fits in background, so more likely to habituate and continue with work
students on other side of door, close to the door, will be distracted, voices are louder so more likely to be sensitized
some might leave room, become angry, etc
if there was no wall, people in middle will exemplify actual behaviour, they can still somewhat hear it, but not too close to it
they might continue with work and be slightly distracted
or they might close the door or ask ppl to be quiet
2 processes can be independent and still work tgt to regulate response
both processes involve or activate state system
but habituation only used to detect stimulus, SR system, very weak response
with sensitization, activate arousal and get stronger response
Neural Substrates: Invertebrate Model System - Aplysia - Kandel
Kandel wanted to study human brain responses
realized it was too complex
so studied something simpler, Aplysia
why focus on Aplysia?
Kandel wanted reductionist approach
spinal cord
things to study like reflexes and nerves
was looking for simpler system than crayfish, etc
habituation, sensitization, classical conditioning can be seen in animals
marine simple creature
limited number of nerve cells
cells are bigger, some can be seen with naked eye
many cells are uniquely identifiable
can go back to a single time many times
some correspond to specific functions
very simple system to study these processes
Apysia
if u touch siphon of Aplysia lightly
both siphon and gill are withdrawn and protected
gill withdrawal reflex
Aplysia retracts gills under mantle to be safe
can do this with repeated light touches
that reflex habituates
Neural Circuits in Aplysia Gill-Withdrawal Reflex
initial light touch on Aplysia's siphon activates gill withdrawal response
if touch repeated
reflex becomes weaker over time or habituates
Aplysia, habituation can be explained like synaptic depression
reduction in synaptic depression (transmission)
when touch siphon, sensory neuron S will fire
gradually will release less of neurotransmitters, so eventually habituates
habituation in Aplysia is homosynaptic
involves only those synapses that were activated during event that is causing habituation
Sensitization in Aplysia
touch tail or siphon will retract or contract
normal and sensitized withdrawal is different
habituation is stimulus specific
tail shock will activate sensory neuron T, which will release neurotransmitter
key sensitization is that it's heterosynaptic
means it involves changes across various diff synapses
includes those that were not activated by sensitizing event
bc of this feature, tail shock increases response to future stimulus
Non Associative Learning - 3 Types
perceptual learning
e.g. when in this room and both sides have different noises, like one side has lab training parrot and other has voices
assume never heard parrot sound
over time, changes happen
u learning to discriminate between two things w/o knowing either
faster learning
happens with repeating stimulus
perceptual priming
previous exposure to sensory stimulus that results in faster recognition
statistical learning
without explicit traning
what we learn is result of what we experience more often
spatial learning
form of statistical learning
study of rats and wasps
Perceptual Learning and Cortical Plasticity
humans and other mammals depend on cerebral cortex
used to process info about stimuli and distinguish meaningful differences in their features
sensory cortices help us establish important differences between various sensory stimuli
range of sensory stimuli that cause particular cortical neuron to fire is called neuron's receptive field
has best frequency that a neuron responds to
responds to specific range of sound best
e.g. if u continue coming here and have parrot using human voice, will differentiate with other voices like higher pitch or tone
won't pay attention to same thing everyday
neuron receptive field changes
results in plasticity
cortical plasticity
receptive fields and spatial org. in cortex exchange over time
e.g. neurons for visual processing become more selective over time and maps in visual cortex could become more organized
neurological studies of rats navigating mazes show that spatial learning depends on …
activity in hippocampus
esp in humans
studies in rats show spatial learning relates to hippocampus activity
John O'Keefe suggested term "place cells" to refer to —
neurons with spatially tuned firing patterns
e.g. if rat goes to a place, one neuron will fire, and if rat goes to diff place, another neuron will fire and not previous one
each neuron has certain preferred location where it responds with maximal activity
place field
animal's inner sense of its location in pace helps lead to place cell responding
spatial learning - london taxi drivers
have to memorize a lot of streets and routes, their neural connections changed and hippocampus got bigger
e.g. same happens with bilingual brain, connections are changed and made, brain change over time
this is related to cognitive maps
Clinical Perspectives of Perceptual Learning
when neural circuits that process sensory info is damaged or very aversive events are undergone, this can affect fundamental perceiving method of brain
affects how process, recognize and learn about stimuli
can affect mental health and quality of life
lab experience vs real life event, sensitization to stress
experience in labs is diff, cuz habituation and sensitization are controlled by lab management
these stimuli are not too arousing due to ethical reasons
stimuli is fairly innocuous
in serious cases, single highly emotional event can lead to lifelong amplification of emotional response to wide range of similar stimuli, which occurs in PTSD
recent studies show that even when very arousing events r not. traumatic, person's susceptibility to certain mental illness can still go up
after an initial stressful event triggered by disorder like depression or anxiety, what could happen?
increasingly stressful small events could lead to additional feelings of depression later
suggested that this tends to happen because some people become sensitized to stress and its related psychological states
more recent studies demonstrate that depressed people show stronger response to minor stressors that healthy people do
through therapy, habituation can occur for…
… mental health disorder, studies are still ongoing
sensitization to stress can contribute to
depression and anxiety disorders
pathological anxiety can be seen as …
exaggerated response to potentially shocking stimuli
results when sensitization to stress associated with fear-inducing events emphasizes person's emotional response to stimuli that is more simple
Human-Machine Interfaces: Regaining Sensory Modalities Through Perceptual Learning
sensory pathway damaged so people won't have that regulation
drugs will target those pathways and the neurotransmitters there
sensory protheses
electromechanical devices that interface with neural circuits that usually process sensory info
cochlear implant, how does it affect new learning?
sensory prosthesis that directly stimulates auditory nerves to create hearing sensations in deaf individuals
virtual speech sounds created by cochlear implants are diff than normal speech
so people using implants will learn how to discriminate between new sounds before starting to understand what they're hearing
likely that changes in speech processing abilities after installations of cochlear implant are result of
cortical plasticity but has yet to be proven in humans experimentally.
