Introduction to Memory Flashcards
Types of amnesia
retrograde and anterograde. Often a mixture.
Retrograde amnesia
memory loss of events before the trauma
Anterograde amnesia
inability to form new memories after the trauma
Who was Clive Wearing?
Suffered brain damage from an infection of herpes encephalitis in 1985 and afterwards presented a memory span of only seconds with both anterograde and retrograde amnesia.
What was Clive Wearing’s perception of his own condition?
Compared it to the feeling of just waking up after being unconscious for many years. He keeps a diary and compulsively writes down when he first “woke up” (over and over again) and crosses out the last entry because now, he is awake for real.
What memory does Clive Wearing still have?
Preserved ability to read music, dress, converse, read in several languages.
Procedural memory in tact?
In addition his nervous system can still change in response to events but it is very different
Types of memory
Declarative and non declarative
Declarative memory
memory for facts (semantic), events (episodic), and “knowing” something. Explicit.
Easy to acquire, easy to forget.
Nondeclarative memory
Procedural (skills, habits, knowing how), classical conditioning, habituation and sensitization. Implicit.
Lashley vs. Hebb: Where is memory?
Lashley: Memories are distributed everywhere.
Hebb: In altered connections between cell assemblies (networks).
Evidence for Lashley’s understanding of memory
1951: Severity of deficits correlated with size of lesions but not with the location of lesions.
Concluded that memories are distributed.
Hebb on memory
1949: Activity strengthens connections.
How many neurons are there in the human brain?
about 86 billion neurons
How many synapses?
Each neuron makes up to 10,000 synapses with other neurons.
Dendritic spines
Synapses form on dendritic spines.
Dendritic spines grow fast to make synapses (plasticity).
Where is the hippocampus?
The head of the hippocampus sits in the temporal lobe
Why is H.M.’s case important?
Through his case we understood that the hippocampus is very important to memory, and that memory is represented in our brains in a modular fashion: the hippocampus is involved in some but not all memories.
What happened to H.M.?
He had bilateral medial temporal lobe damage from surgery to control epilepsy (1953), removing parts of the cortex, amygdala and hippocampus. Basically had no hippocampus.
What were the outcomes of H.M.’s brain damage?
Had partial retrograde amnesia and severe anterograde amnesia without the ability to form new memories explicitly
What were H.M.’s remaining abilities?
Had a normal short-term memory.
Procedural memory system in tact.
Star drawing: normal people can do better each time; HM would get better at it but he did not remember it.
The hippocampus is important in ___ memory
Spatial
Evidence for the hippocampus’ involvement in spatial memory
Hippocampus damage in rats lead to decreased performance in a radial arm maze. “Place cells” in the hippocampus “code space.”
Evidence that sleep can strengthen your memories
Activity of hippocampal place cells during a rat’s dream after a maze
London taxi drivers and hippocampus
Relationship between how long one has been a taxi driver and the size of their posterior hippocampus.
Less able to do vocal memory task.
