lecture 7 - learning and memory Flashcards
(18 cards)
Temporal lobe is specificallly involved in memory
History of locating memory in the cortex
- Gall (early 1800s) - tell someones personality by looking at bumps on their head - has no scientific basis = psuedoscience - First idea diff parts of brain involved in diff processes
- Broca and wernicke (mid 1800s) - different parts of the cortex have different functions
- Brocas area - near motor cortex - language production - if damaged can make sounds but struggle to form words
- Wernickes area - near auditory cortex about comprehension
- Karl lashley (1900s) - worked with rats - trained on maze then damage parts of the brain (leisoning)
- mass action - entire cortex involved in everything
- equipotentiality - if you remove one part, another part of the cortex fills in
First clue memory was localised in the brain came from Von Bechterew (early 19th CE)
- Worked with patients with marked memory impairments
Marked softening of the temporal lobe - correlated with memory function - more softening = worse memory
Patient HM
Severe epilepsy rendering him unable to work. Not controllable by drugs. Gave us most of our knowledge of memory. He had lots of seizures - hug impact on quality of life
At 53 drs identified source of seizures = medial temporal lobe - so removed it bilaterally to stop the seizures - at the time no evidence or reason they thought anything negative would happen
Seizures were reduced - but he had memory impairments
Had head scans by corkin
HM’s memory
Severe anterograde amnesia - since lesion
Graded retrograde amnesia - prior to lesion - further away from surgery the better his memory
Episodic memory was hugely impaired
HM - working memory
Not all memory was problematic for HM. Eg HM had intact working (or short term) memory
- normal digit span (remembering numbers)
- wickelgren (1968) showed rate of forgetting within normal range ( unless interrupted from constant rehearsal)
Struggled on non-verbal short-term memory - impaired
Procedural memory in tact
HM could learn new motor tasks, for example the mirror tracing task (milner 1962, 1965)
Sit someone in front of mirror cover hands, can only see hands in mirror and ask them to draw a pencil line, he made lots of errors to start with but as he practiced he performed better. He would come back next day and have no conscious memory of task or person and he has retained some of that learning. Task improved day by day.
HM has an impairment in declarative memory
graph in notes
Declarative vs procedural memory systems
Declarative - memory of facts and experiences
Procedural - skills and tasks
HM has a single dissociation - has declarative not procedural memory
Double dissociation - impaired procedural but fine with declarative memory eg have a cerebellum impairment
Good evidence the two types of memory are different and seperable
HM failed particulary in episodic memory
diagram in notes
Animal model of human amnesia
Non-matching-to-sample task (Mishkin 1978)
the delayed non-match to sample task - a monkey first displaces a sample object to obtain a food reward. after a delay, two objects are shown and recognition memory is tested by having the animal choose the new object that does not match the sample such that to get the food award underneath the new object
graph in notes
indicates more adjacent cortical tissue damaged
Damage to the perirhinal cortex impairs recognition
diagrams in notes
Perirhinal cortex vs hippocampus
Perirhinal cortex (PRC) and hippocampus (H) have different roles in memory
Must be able to recognise whats novel and what is familiar
diagrams in note
What roles does the hippocampus play in memory?
role in spatial and episodic memory
burgess et al 2002
fMRI shows right hippocampus is active during spatial memory tasks
Spatial memory:
Food-storing birds have larger H
Sherry & Duff (1996)
e.g., Scrub-Jay has been studied
extensively due to evolved ability to
store food (below pic from Cambridge
laboratory)
graph in notes
Taxi drivers vs bus drivers - Maguire
Further evidence that hippocampus is involved in spatial memory comes from
looking at the hippocampus in London Taxi Drivers versus London Bus Drivers
Size matters…
Maguire et al. (2000)
Taxi drivers show experience-related changes in the
size of the hippocampus
Posterior hippocampus is larger, and the anterior
hippocampus is smaller
The size of the hippocampus is correlated with time
spent as a taxi driver (that is, longer spent as a taxi
driver, larger posterior hippocampus
graphs in notes and rey-osterrith figure
Hippocampus:
Papez Circuit
Damage to Mammillary bodies / Anterior
Thalamus causes memory deficits
Patient RB - Selective lesion of CA1 region
diagram in notes
Main conclusions
Lashley got it wrong (at least in part)!
Human & animal studies: established role of the medial temporal lobe in
memory
Support for declarative/procedural distinction
Perirhinal cortex= object memory/familiarity
Hippocampus = episodic memory and spatial navigation
Hippocampus part of Papez circuit
“Acquiring ‘the Knowledge’ of London’s Layout Drives Structural Brain Changes” by Woollett & Maguire (2011)
Study Focus
Investigates whether learning complex spatial information (London’s street layout) causes structural brain changes in adult humans.
Uses longitudinal data to distinguish cause and effect, unlike previous cross-sectional studies.
🚖 What is “The Knowledge”?
Training required to become a licensed London taxi driver.
Involves memorizing ~25,000 streets and thousands of landmarks.
Takes 3–4 years of intensive study and practice.
👥 Participants
79 male trainees at study start (Time 1, T1).
3 groups formed by Time 2 (T2) after 3–4 years:
Q: Qualified drivers (n = 39)
F: Failed to qualify (n = 20)
C: Control group (n = 31, no training)
🧪 Key Findings
📊 At Time 1 (Before Training)
No significant differences in:
IQ, education, memory performance, or brain structure (incl. hippocampus) across groups.
All groups started on equal footing.
📈 At Time 2 (After Training)
Only the qualified group (Q) showed:
Increased gray matter in posterior hippocampi (bilaterally).
Better spatial memory (e.g., proximity of landmarks).
Worse visual memory (e.g., delayed recall of complex figures).
No structural or memory changes in:
F (failed trainees)
C (controls)
🧬 Interpretation
Changes in posterior hippocampus are caused by acquiring “The Knowledge.”
Suggests the hippocampus is plastic and can adapt in adulthood through real-world cognitive challenges.
Anterior hippocampal shrinkage (seen in previous studies) wasn’t yet observed, implying changes might occur in stages.
🧩 Possible Biological Mechanisms
Neurogenesis (new neurons form during learning).
Synaptogenesis (new connections between neurons).
Dendritic growth and glial support may also contribute to volume changes.
⚖️ Implications
Supports neuroplasticity in adult humans.
Encourages lifelong learning and potential for neurorehabilitation.
Raises questions about:
Individual differences (e.g., genetic predisposition).
Potential trade-offs (e.g., spatial memory vs. other memory types).
📌 Conclusion
Learning “The Knowledge” causes measurable changes in the brain.
Highlights the importance of environmental stimulation for adult brain plasticity.
Reinforces the idea that cognition is not fixed, contributing to the nature vs. nurture debate
