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Early Memories/Early Experiences - Coggle Diagram

- - - - Campbell and Campbell (1962)
        
        what did they do?
        
        Testing the retention of the memory after different test intervals.
        
        passive avoidance procedure.
        
        used 18 day old, 23 day old, and 100 day old rats
        
        what did they find?
        
        18 day olds drop down to 25% retention after a week, after a month they've completely forgotten.
        
        23 day olds don't really completely forget until 2 months
        
        100 day olds have almost perfect retention
        
        interpretation: 18 day olds show either a lack of memory, or a memory that isn’t affecting their behaviour.
        
        more likely a lack of memory
      - Richardson and Campbell (1991)
        
        what did they do?
        
        examining changes in heart rate in response to exposure to something novel
        
        used P16, P30 and P75 rats over 20 trials over 2 days (10 trials each day).
        
        heart rate decreases in response to something new.
        
        Heart rate staying at baseline is good retention.
        
        not exactly sure what the procedure was > assuming they exposed the rats to a novel object over 10 trials on day one, and then the next day they showed the same object over 10 trials to determine if the rats remembered
        
        what did they find?
        
        day 1: all rats had a sharp mean decrease in heart rate compared to baseline for up to 5 trials. from trial 5 their heart rate rose back to base line.
        
        day 2: from trial 1 the P30 and P75 rats had mean heart rates closer to baseline, but the P16 rats had almost the same results as the day before.
        
        interpretation: Infantile amnesia is also associated with simple, non-associative learning.
  - - - Infants have the same learning capacity as adults, it’s just that they forget much quicker
        
        Something may be happening in the brain where the memory is harder to access, it disappears, or it doesn’t get put in long-term storage.
      - Rovee-Collier et al (1980)
        
        what did they do?
        
        trained 2 month olds on the mobile task and then a month later had a reactivation procedure (3 min of exposure to the mobile)
        
        what did they find?
        
        reactivated memory was much worse than original.
        
        interpretation: failure of reactivation suggests a failure to properly recall/retrieve the original memory, making it so there's not really anything to reactivate properly (?)
  - - - Some species are born precocial (babies born looking the same as adults, not reliant on care from an adult)
        
        are born with more mature brains, do not experience infantile amnesia
        
        Altricial (more development needed outside of the womb, dependent on a caregiver)
        
        what did they do?
        
        trained guinea pigs (i think??) at P5 or P100 in a shock-motivated t-maze (shocks stop in a safe area) to see what % correct they are in the maze.
        
        acquisition phase of 10 trials
        
        75 day delay
        
        either weak (20 trials), moderate (40 over 2 days), or strong (100 over 5 days) relearning period.
        
        what did they find?
        
        animals that were very young at training did just as well during re-test as adults
        
        interpretation: lack of infantile amnesia
  - - - The older a memory is, the more stable and entrenched it’s likely to be. You will see less of an impact of neurogenesis on the memory.
        
        Forgetting is functional; in a healthy memory system, there are some things we need to forget to make room for other things.
        
        The memory system is limited, and we need room to make sure we can adapt to changes in the environment.
        
        Forgetting induced by neurogenesis allows us to learn new things faster.
- - - - Rat mothers often need to leave the babies for short periods of time to find food > 15-20 mins at a time, unless living in a low-resource area, then it’s a couple hours.
        
        Increases the mother’s stress since she’s not wired to spend that much time away from the pups.
        
        Face validity for the stresses experienced by humans > similar to rat mum and pups > increased stress hormones.
        
        Standard-reared pups show infantile amnesia, and maternally-separated pips show persistent (“adult-like”) memories.
  - - - The activity of the mPFC will start in juveniles.
        
        mPFC active during learned fear expression for older animals (from P25) but not infants (Li, Kim & Richardson, 2012).
        
        Also active in MS (maternal separation) infant rats: Pavlovian conditioning P17 Test P18, perfuse +1hr (Cowan, Stylianakis & Richardson, 2012)
        
        Showed an accelerated rate of memory > mPFC cortex is coming online early compared to SR (Standard reared).
    - - Amygdala – PFC connectivity > positively coupled in childhood (light up together), negatively coupled in adolescence (one or the other one at a time).
        
        Regulatory function of the PFC.
        
        During childhood, neurons that fire together wire together, but with practice, it gets more nuanced.
        
        Children in institutional care, are then adopted into American families. All placed into care by 3 years old, and adopted relatively young. Spent at least 2 years with new family:
        
        Negative amygdala – PFC coupling in childhood
        
        Like rats, show a more mature pattern of response in the brain, just early.
        
        Shown through a study where they got the kids in an fMRI and showed them pictures of happy and sad faces.
  - - - Accelerated development is related to stress, and therefore may have negative consequences in the long run.
        
        Generational effect.
        
        Those shown to have accelerated maturation are shown to have more anxiety > the most latency in a passive avoidance procedure > maxing out test times without going in the dark side of the box.
        
        More likely to remember a difficult experience, and more likely to be more sensitive to future negative experiences.
    - - Shown through a study where they got the kids in an fMRI and showed them pictures of happy and sad faces.
        
        Red = negative connectivity > negative group in brain scan who had been institutionalised showed LESS ANXIETY.
        
        The faster maturation may help the child to adapt to their unstable world.
        
        Mismatched hypothesis: environment during childhood is the best predictor of environment during adulthood. There’s a mismatch when the adult environment doesn’t match the childhood one. If you can’t trust your environment based on your past experiences, you’re vulnerable to psychopathology.
        
        The amygdala lights up where an emotion is in your view, but when it’s a parent, the amygdala is not as active > parental buffering
        
        Solid line= more immature response > parental buffering
        
        Adolescents will no longer show that diminished amygdala response with parents.
        
        PI children showing a less mature pattern the first time show an improvement in their anxiety, but if it was more mature to start with, then its higher.