Lecture 5: How many types of memory are there? Flashcards
William James (1890)’s Principles of Psychology
Distinguished between primary and secondary memory
Lashley’s Law of Mass Effect
“The degree of (memory deficit) seems proportionate to the amount of tissue destroyed, irrespective of the locus of the injury”
Case study HM:
Had frequent seizures throughout his life
Eventually opted for bilateral removal or medial temporal-lobe resection
Retrograde Amnesia (memory damage)
Childhood memories
Anterograde Amnesia - (Memory damage)
Can’t remember new experiences
What happened to HM as a result of the removal:
Anterograde amnesia
Immediate memory loss
Partial retrograde amnesia
Retained memory for early childhood
How to formalise H.M’s impairment
Formal test - IQ (112) and MQ (67)
HM unimpaired at delayed match-to-sample tasks explained
In zero delay condition his memory was unimpaired - intact STM
Could remember trigrams for 40 seconds no evidence for STM
Main thing H.M. proved about memory
Short and long term memory are two distinct stores
Brain regions that support working memory in humans:
Frontal lobe patients are impaired at organized search (working memory)
People with frontal lobe lesions make more errors at higher loads (Owen et al, 1990)
Neural mechanisms for maintaining information in brain (persistent activity):
Money had to remember which location the apple was in and respond by touching the apple
Huge cluster of neurons found in the delay period when the monkeys had to remember the location of the apple
Key points about different neurochemical systems in the brain
Different neurotransmitter systems project to different brain regions
Each neurotransmitter can bind to specific types of receptors
Spatial delayed alternation task
Trial 1 visit one location
Trial 2 visit another
Trial 3 revisit location 1
Vice versa
Vary the delay period between trials
Brozoski et al, 1979 Dopamine findings
Depletion of dopamine has been found to impair working memory performance in moneys
Serotonin and noradrenaline no effects
Effect of Methylphenidate on spatial working memory:
Prescribed for people with ADHD
Works by blocking the dopamine transported (DAT) and the Noradrenaline reuptake transporter (NET)
Preventing dopamine and noradrenaline reuptake
Leaving more dopamine in the synaptic cleft
Effect of Methylphenidate: Within-Subject design PET scan results
Improved performance
Likely by affecting the dorsolateral prefrontal cortex
Part of brain responsible for STM
Prefrontal cortex (dopamine)
Part of brain responsible for LTM
Hippocampus
Task to test memory for skills
In mirror tracing participant has to trace the line between two star shapes - inner and outer shape. Without touching the lines, can be as hard as left and right reversed
HM mirror learning (Milner, 1962)
Progressive improvement overtime
Declarative LTM (Explicit)
Storage for facts, events and locations
Non-Declarative LTM
Storage for learned skills, habits or relationships
Patients with amnesia learning habits: Knowlton et al, (1994)
Tested 8 amnesiacs matched with 37 controls
Patients with amnesia were able to learn the task
Patients were systematically asked about the layout of the screen and various other details they did poorly
Can do the task with amnesia but have no conscious memory for it.
Effect of Parkinson’s on dopamine
Pronounced disruption to dopamine cells
Dopamine depletion
Effect of Parkinson’s in learning habitual responses: Knowlton et al., 1996)
- People with PD performed significantly worse on the weather predictions task (test of habit formation) then controls or patients with amnesia’
- Despite this, patients had fully knowledgeable and recollection of the task. Unlike amnesic group.
One -shot learning definition
an ML-based object classification algorithm that assesses the similarity and difference between two images
Which type of LTM is one-shot learning?
Declarative
Which type of LTM is habitual learning?
Non-declarative
Which part of the brain is one-shot learning?
Hippocampus
Which part of the brain is habitual learning
Striatum
Priming definition
Priming is the change in behaviour that results from previous exposure to an item or stimulus.
Verbal learning in amnesiacs: Warrington and Weiskrantz, 1970
Presented with 3 lists of 9 words tested on their retention of these words under different retrieval conditions (of degradation) Counted number of presentations of non-fully degraded word
- Direct recall, and recognise- Another exposure to degraded words
- Tested four patients with amnesia and 6 controls (Matched for age and intelligence)
- Number of errors (not identifying the word from degradation shown
Verbal learning in amnesiacs: Warrington and Weiskrantz, 1970 results
- Amnestic patients show evidence of learning
- Recall - amnestic groups do poorly- Can recognise words from their fragmented forms
Does priming depend upon the hippocampus: Schater et al (1996) Method
Used PET scan with radiolabelled Co2
Participants study 24 words, had to say “t” junctions in a word. They were shown these words in the scanner with three letter primes. Had to complete the words
Does priming depend upon the hippocampus: Schater et al (1996) Results
When participants are responding to primed (cues) compared to novel words they show reduced blood flow in visual cortex (Schater et al, 1996)
Schater et al (1996) Priming experiment
- they compared blood flow when responding to novel words (completing unseen words) to blood flow when completing the stems for seen words (e.g., having seen the word PICNIC and then shown PIC)
- Authors found decreased blood flow in visual cortex when viewing primes
- No change in blood flow in the hippocampus
“what brain regions are more active when trying to complete the words for non-semantic condition to novel words”
- Praecuneus (medial parietal lobe)
- Left prefrontal cortex
What brain regions are more active when trying to complete the words for the semantically primed words (“PIC_____”) compared to the novel word (“REC”)
- Find: left and right (posterior) hippocampus
- So the hippocampus is argued to be involved in conscious recollection
Korsakoff (1989) gave patients with amnesia an electric shock:
- Patient has no memory of receiving the shock, but when shown the briefcase they suggested he probably came there to shock him
- Even in the absence of conscious recollection patients with amnesia can remember aversive experiences unpleasant stimuli that induce changes in behaviour via negative reinforcement or positivepunishment
Bechara et al, 1995 examined the effect of lesions to the hippocampi, amygdale or both an aversive conditioning:
Habituation phase (exposure to neural stimuli)
Skin conductance response: exposure to an arousing stimulus (or novel) stimulus activates sympathetic nervous system
