Learning And Memory Flashcards
Who was one of the earliest investigations of the brain mechanisms of memory?
Karl Lashley (circa 1929). Although he showed that large lesions of the Cortex could impair memory, he was unable to localise memory itself, which he called engram, to any particular part.
Why must memory involve many different systems within the brain?
Because memory is made up of many sub-processes, such as perception, storage, and retrieval.
How did we get to know much of the brain and memory in humans?
From just one patient, H. M.. He was given a bilateral temporal lobectomy to reduce his severe epilepsy. Tragically, the operation produced a dramatic anterograde amnesia , in which the person cannot learn new information, although memories from before the operation are largely spared.
What do findings from H. M. and other amnesia patients suggest?
Damage specifically to the hippocampus is responsible for amnesia.
What was the particular problem of H. M.?
His particular problem was transferring material from his short-term memory into his long-term storage, although he can lern and retain simple visuo-motor skills.
What do chronic alcoholics sometimes suffer from?
Chronic alcoholics sometimes suffer from Korsakoff’s psychosis, one symptom of which is severe anterograde amnesia. Alcohol-induced brain damage does not involve the hippocampus, but affects structures in the diencephalon such as the thalamus and the mammillary bodies.
What are the suggestions Korsakoff’s amnesia have led to?
Korsakoff’s amnesia is more a problem of inefficient storage and retrieval, and the different patterns of brain damage and amnesia have led to the suggestion of two separate categories of temporal lobe and diencephalic amnesia. It also seems that all forms of amnesia usually affect our personal or episodic memory more severely than our semantic memory.
Alzheimer’s disease patients (pre-senile dementia) can show severe memory loss. As the underlying brain damage involves dramatic loss of of acetyl-choline neurons, it has been suggested that treatment with drugs stimulating acetylcholine could be effective. What were the results?
The results have been disappointing. Work in rats shows that grafts of acetylcholine neurons can restore cholinergic function, but there are many difficulties in applying this approach to humans.
What did studies in rats, that were investigating retrograde amnesia show?
Retrograde amnesia in rats has been systematically studied using one-trial passive avoidance learning and electro-convulsive shock. Results show that immediately after learning, memory is in the form of vulnerable electrical neural circuits. Long-term memory involves structural changes to neurons, possibly the growth of new synaptic connections, and is much more resistant to disruption.
The biochemical bases of memory are likely to involve the DNA and RNA of the neuronal cell nucleus. What did early studies try?
Early studies tried to transfer learning by feeding or injecting brain tissue from trained animals to naive animals. This controversial research area has now faded out.
What have Kandel’s group shown?
Kandel’s group have shown that the biochemical basis of simple leaning is aplysia, a sea-living mollusc, is an increase in neurotransmitter release at key synapses.
What has recent work identified as possible learning mechanism in more complex animals?
Recent work has identified long-term potentiation in the hippocampus as a possible learning mechanism in more complex animals. Stimulation of some circuits makes those circuits more likely to fire in the future , by altering neurotransmitter release and stimulating the growth of new synaptic connections.
