learning and memory

history of locating memory in the cortex- pre

Gall (early 1800s) - tell someone's personality by looking at bumps on their head

Broca and Wernick (mid 1800s) - different parts of the cortex may have different functions

Karl Lashley (1900s) - worked with rats - trained on maze then damage parts of the brain (lesioning)

◦Mass Action - entire cortex involved in everything

◦Equipotentiality - if you remove one part, another part of the cortex fills in

History of locating memory in the cortex

First clue that 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

Lashley concepts

◦Mass Action - entire cortex involved in everything

◦Equipotentiality - if you remove one part, another part of the cortex fills in

Who first suggested that memory might be localized in the brain?

Von Bechterew in the early 19th century.

What did Von Bechterew observe in the brain to suggest memory localization?

Bilateral softening in the brain was often associated with memory issues.

What accident did Patient H.M. experience at age 7?

He fell off a bike and began experiencing seizures (epilepsy).

Why did doctors decide to operate on H.M.?

Seizures became so frequent he couldn't work; brain recordings showed seizure activity started in the medial temporal lobe.

What part of H.M.'s brain was removed in surgery?

The medial temporal lobe bilaterally (on both sides).

What happened to H.M.'s memory after surgery?

His seizures stopped, but he had catastrophic memory impairments.

What kind of amnesia did H.M. have after surgery?

Temporally graded retrograde amnesia — older memories were better preserved than recent ones.

Was H.M.'s working memory intact?

Yes, he had normal digit span but couldn't move information from working memory into long-term memory if distracted.

What type of learning was still possible for H.M.?

He showed improvement across days, indicating preserved procedural memory.

What distinction did H.M.'s case lead to in memory research?

Between declarative memory (impaired) and procedural memory (intact).

What is a single dissociation in memory research?

One type of memory (e.g., procedural) is intact while another (e.g., declarative) is impaired.

What is needed to prove a double dissociation in memory systems?

Another patient showing impaired procedural but intact declarative memory — seen in some cerebellum injury cases.

What memory types are part of declarative memory?

Episodic and semantic memory.

How was H.M.'s IQ after surgery?

It remained intact or even improved, despite memory issues.

What task was used in monkey studies to investigate memory structures?

Delayed non-matching-to-sample (e.g., choose the new object for a reward).

What did removing the hippocampus and surrounding tissue in monkeys show?

Most memory impairment occurred when surrounding cortical areas (like PRC) were removed.

What does PRC damage affect in both monkeys and humans?

Object recognition.

In rat studies, how was recognition memory tested?

By presenting a familiar object and a new one; rats explored novel objects more.

What happens when rats have hippocampal lesions in object recognition tasks?

Performance isn't heavily affected unless surrounding areas like PRC are also damaged.

What kind of memory is the hippocampus especially important for?

Spatial memory — recognizing spatial layouts and navigating environments.

What technique improved our understanding of memory function in humans?

MRI (Magnetic Resonance Imaging).

What brain changes were seen in food-storing birds?

Larger hippocampus size compared to non-storing birds.

What difference in hippocampus size was observed between taxi and bus drivers?

Taxi drivers had a larger posterior and smaller anterior hippocampus.

What does hippocampal change in taxi drivers suggest?

Brain structure can change (plasticity) in response to learning and spatial navigation demands.

How did taxi drivers perform compared to bus drivers in different memory tasks?

Taxi drivers were better in spatial memory; bus drivers better in other areas.

What was Lashley's argument about brain function and memory?

That memory might be distributed rather than strictly localized — supported by the idea of memory networks.

What does it mean that the brain forms networks to support memory?

Memory isn't isolated to one structure; multiple areas communicate and work together.