PSY260 - 13. Time Memory Flashcards by Darlin Veloso

Time Memory

Bees +other animals remember time of day they discovered food (food anticipation)
Marmosets learn which box will contain food, but assume restricted to 1 time of day

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Time Memory

Hamsters + mice learn where find food/receive foot shock + what time of day will happen
Human beings have distinct times of day they will perform specific tasks/actions

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Time Memory

ability to learn + remember time of day when things happen
implicitly remember time of day
food not available all day long - remember time accessible

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Time Memory

do a dance to communicate info to sister bees
never taught to them explicitly
we have various devices that tell us the time
don’t think about it - you know it

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Episodic memory

autobiographical, places individual at scene of memory (it is your memory, and you know that you were there)
time is critically important for episodic memory

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Episodic memory

don’t know if animals simply learned association/know it’s happening, if they have episodic memory
animals behave in tests that indicates they might be using episodic memory
we don’t know how they are accessing that memory

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Episodic-like memory

memory of what/when/where but no concrete evidence of autobiography

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Explicit time memory

time of day discriminative cue + part of context that must be learned
explicit: avoid chamber at 2, not at 6, get shock in afternoon, not at night

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Implicit time memory

time of day not discriminative cue

memory implied by response of subject

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Implicit time memory

train at 1 time, no info about what happens at another time, yet perform at time of day trained, not any other time

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Implicit time memory

Animals automatically register time of day that significant conditions occur
Animals expect recurrence of condition at same time on subsequent days
measurement of learning depends on when you measure memory

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Implicit time memory

has to be significant for animals, not for humans

if tested at diff time of day, might conclude that it hasn’t learned

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Conditioned Place Preference or Avoidance

Day 1: Pre-exposure (10 minutes)
animals allowed access to both chambers
no preference

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Conditioned Place Preference or Avoidance

Days 2-9: Conditioning (5 min/day, 1 time of day) - animals confined to single chamber on each day - Chamber is alternated each day - reward is paired with ONE chamber
teach them to prefer a chamber - time not discriminatory
next day give nothing in other context at same time

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Conditioned Place Preference or Avoidance

Day 10+: Testing (20 minutes)
animals allowed access to both chambers
tested at a clock time which either matches/doesn’t match training time

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Post-training context preference: animals trained at CT 13 (late day) with wheel reward

test at same time: preference for paired context

no significance preference at diff time of day

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Post-training context preference: animals trained at CT 04 (early day) with wheel reward

paired at early day: show significant preference at early day
no significant preference in late day
takes energy + risk to go foraging for food: so organisms assess likelihood of getting reward + go out when they have experienced reward before

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Conditioned Place Avoidance

mild footshock
strong avoidance same chamber 24 hours
don’t show strong avoidance at 32 hours, 40 hours
comes back at 48 h
avoidance occurs every 24 hours at same time of day

Passive avoidance

Performance of passive avoidance depended on matching of time of training + time of testing, regardless of time of training.

Passive avoidance

1 training experience
rodent placed in start box with bright light, door to dark box
wires allow researcher to put footshock, rat wants to go to dark
immediately after footshock goes to light

Passive avoidance

takes longer for animal to go back into dark
strong 12 + 24 hour components in response
learning expressed at 24 hour intervals

CPA time stamp persists in arrhythmic SNC-lesioned hamsters

The time CPA stamp rhythm, like CPP, not based on SCN biological clock
oscillator governs time
lesion has no effect on learning

Passive avoidance at 2 shock levels in the mouse

apply footshock sufficient to induce fear responses, you don’t see rhythm
experience so bad it won’t go back into the dark at any time
reduce the intensity - longer time to go back when on time
will go back early/late
fear conditioning induced at 1 amp
this is anxiety conditioning

Passive Avoidance

scn lesion shows no effect on learning

still remember time of day they learned

Conclusions

Animals learn time of day significant conditions occur – even when timing not explicit condition of task don’t need to know what happens at other time of day

Conclusions

The underlying oscillator set rapidly – at time of stimulation biological clock not directly involved in learning SCN (biological master clock) not required for time memory

Conditioned place avoidance

time of day is critical - physiological changes, wake/sleep ability to recall explicitly learned info have preference for learning at certain time of day before puberty - prefer day, after puberty - prefer evening

Conditioned place avoidance

training animal to avoid footshock at particular time of day after 5 + 18 days, still remember time of day trained at 11, when they’re active

Conditioned place avoidance

they remember at 3, don’t avoid it at 11 after 5 days, they seem to forget, lots of variability after 18 days, they have completely forgetten

Conditioned place avoidance

appear to forget, but test them later in day, find they remember train these animals late in day, they remember for at least 18 days train in the middle of day, seem to forget after a couple of days

Conditioned place avoidance

test them later, they show that they remember avoided at training time in 5 days after 5 days, trained at day less diff behaviour than other times they remember at 11 days, but they get time wrong, they perform just as well at time of day as ones trained at 11

Shifting Clock

Wheel Running animals run, measure how much they run every 6 seconds nocturnal animal runs at the dark timing of light cycle shifts + animal changes its timing

Shifting Clock

18 days later, what time of day they avoid footshock now that we shifted timing, they avoid few hours later when they think it’s 11 this internal clock associated with light + dark

Shifting Clock

trained at day, shifted at opposite direction, still show avoidance behaviour at same time clock doesn’t pay attention to light/dark no matter what always at 11, no need for light cycle

Shifting Clock

train at inactive time, response time has shifted over to beginning of its activity clock is set when animal learns something so days later, animal will anticipate when condition happens again absence of reinforcement, no sense in remembering time

Shifting Clock

time of day shows anticipation is time of day when begin to be active whe it’s most likely to encounter the danger/reward, when it is motivated to forage

Summary

Performance on context learning tasks depends on synchrony betw times of training + testing

Summary

phenomenon doesn't require suprachiasmatic nucleus

Summary

assumes it’s not gonna occur at another time of day | central clock that produces circadian clock

Conclusions

Brain mechanisms involved in learning + memory are rhythmic, + time of conditioning is registered by setting of intrinsic rhythm

Conclusions

Time of day memory does not provide “when” used to define episodic memory all of these systems are rythmic (nucleus accumbens)

Conclusions

when something important happens, oscillators change timing, set by experience hippocampus pays attention to what, where + when it happens

Conclusions

does this by changing oscillator timing don’t hold time in same storage system as other attributes of environment because timing changes over few days when changes all the time

Conclusions

episodic memory order of episodes + understanding order they occur time of day memory is transient, not like episodic like memory