intro to learning and memory

what is memory, and what is it good for?

• purpose to influence future actions

• modification of structure or behavior

learning/memory often increase fitness, though not always the case

exception to learning and memory increasing fitness: PTSD

• mental health condition developing due to shocking/dangerous event

• symptoms

  • flashbacks, bad dreams

  • avoidance from places that are daily reminders of experience

  • being easily startled, feeling tense, insomnia

takehome

• memory is not always beneficial

• understanding brain mechanisms may help treat PTSD and memory-related diseases

memory research in humans vs rodents

humans

• clinical cases

• psychophysics

• fMRI

• EEG

rodents

• behavioral tasks

• lesions

• interrupting brain activity

• recording brain activity

memory types map

short vs long term

short term memory

capacity for storage of small amounts of info in an accessible state for a short period of time (s)

example: remembering a phone number until jotting it down

items short term memory can hold

1956 article by Miller

• number of objects a human can hold in short term memory is 7 plus/minus 2

• LATER: memory span is not constant as it varies for digits/letters/words; lower for long words than for short words

short term vs working memory

• working memory involves temporary storage of info to manipulate it

  • storage + processing

examples: remembering partial results while calculating

immediate free recall task

• presented with sequence of items → asked to report all items in any order

• recency effect: then final few items are reported with higher probability

• final items are STILL in short term memory

distractor task

• immediately after item sequence, perform a distraction task

• eliminates the recency effect

• by the end of the distraction task, the recent items have been deleted from short term memory

short term memory behavioral test in animals: DMS

delayed-match-to-sample (DMS) task

• view object in monitor, delay, another object is presented, detect if a match based on location or object

long term memory

• lasting storage of information

• general stages: encoding (consolidation) → storage (reconsilidation/extinction) → retrieval

declarative vs non-declarative memory

declarative (explicit)

• memory you can consciously recall or declare

non-declarative (implicit)

• memory that is expressed through action, not recollection

types of non-declarative memory

• procedural: knowledge of how to do something (ex: ride a bike)

• conditioning/associative learning: association between items (ex: green light signals to drive)

non-declarative classical conditioning (Pavlovian conditioning)

• originally studied how NS controls digestion

• found that dogs salivate in response to sight of food OR to sound of a bell

• common paradigm: fear conditioning

unconditioned stimulus: naturally evokes an unconditioned response

conditioned stimulus: paired with US so that it evokes a response

response to the CS is known as the conditioned response

operant conditioning (instrumental conditioning)

• learning through reward and punishment

• type of non-declarative memory

classic vs operant conditioning

classical:

• neutral signal before a reflex

• non-voluntary behavior

operant:

• reinforcement after behavior

• voluntary behavior

behaviorism (Watson)

• human behavior can be fully accounted for by classical and instrumental conditioning

• discounts independent thought, feelings, imagination, creativity

little albert

teaching a boy with classical conditioning

• originally not scared of white rates

• struck with loud noise and presence of white rats → fear of white rats (acquired fear)

• reacted fearfully to similar shaped objects (dog, rabbit)

declarative explicit memory

• semantic memories (memories of facts)

• episodic memories (memories of events)