L7 Flashcards
what was Lashley’s principle of “mass action”
it stated that memory is distributed throughout the cortex and that there is no specific region for memory
what experiment did Lashley do to test for the principle of “mass action”
he made small lesions on different parts of the brain to see if that damage would have an effect on memory
it didn’t
what parts of the brain did HM have removed
the hippocampus, temporal lobe and adjacent structures (rhinal cortex)
what did HM experience after the operation
anterograde amnesia
retrograde amnesia (post 2 years)
intact short term and remote memory
IQ improved
only lost declarative memory
what do HMs deficits show
dissociation of intelligence and memory
hippocampus, medial temporal lobe structures are involved in memory
consolidation
dissociation of declarative memory from working and procedural memory
where are the structures for declarative (explicit) memory located
medial temporal lobe and diencephalon
what is an ischemic episode
when blood flow to the brain is reduced
what did patient RB experience after an ischemic episode
selective, marked anterograde amnesia and very minor retrograde amnesia
what happened to RBs hippocampus
all of RBs CA1 cells have gone which seems to have caused his loss of memory
why when testing for memory would you ask the individual to copy an image first before asking them to draw it from memory
you have to make sure it is not a visual or muscle control defect
if they can draw it good the first time, then when they are asked to reproduce it you know that if they cant do it, it is because of their memory
when asked to reproduce an image what difference would be seen between someone that ONLY had hippocampal damage compeered to someone that had all the areas damaged in HM
the individual that only had hippocampal damage would be able to remember some features of the image (not a lot but something)
whereas someone with hippocampal and rhinal damage wouldn’t be able to do it at all
what is diencephalic amnesia
it is amnesia like HM experienced
why does diencephalic amnesia get its own special name
because it is a specific part of the brain that is damage to result in this
these regions have to do with the mammillary bodies and thalamus (maybe fornix)
what is Wernicke-Korsakoff Syndrome
This syndrome, which occurs in heavy drinkers, produces similar
memory deficits to those that result from temporal lobe damage
what is Wernicke-Korsakoff Syndrome caused by
lack of thiamine (vitamin
B1) which affects the brain and nervous system, rather than by
alcohol directly.
Lack of thiamine can occur because:
Many heavy drinkers have poor eating habits. Their nutrition is inadequate and
will not contain essential vitamins.
Alcohol can inflame the stomach lining and impede the body’s ability to absorb
the key vitamins it receives.
what might Wernicke-Korsakoff Syndrome also be known as
‘wet brain’ or ‘Beriberi’
what regions of the brain are damaged in Wernicke-Korsakoff Syndrome
the dorsomedial nucleus of the thalamus and the mammillary bodies
explain the extended hippocampal diencephalic memory system
the thalamus is the relay station
the hippocampus receives information about what the object is and where it is in space. It then binds this information together and is held in there for a period of time and then set out through the fornex to the mammillary bodies
Recent memories sit in the hippocampus and they start to make associations to neurons in the neocortex and will eventually become independent to the hippocampus
explain the extended hippocampal diencephalic memory system in terms of retrograde amnesia
memories are stored in the hippocampus for a period of time. when the hippocampus is damaged it is the memories that are being stored in there that are lost
if the memories have become independent from the hippocampus then it is likely that they are spread all round the brain and they will not be lost
where are memories located
old are all around the brain
new are in medial temporal lobe
how do we represent our location in space
out reference frame can either be egocentric or allocentric
what is egocentric
the frame of reference is the individual
e.g. left/right, in front of me
what is allocentric
the frame of reference is the external world
e.g. north, south, to the east of the tree.
between the tree and the house
what would you notice when you put rate with hippocampal damage in a morris water maze compared to normal rats
normal rats will find the platform easily from a variable (allocentric) and a constant (egocentric) start
whereas rats with hippocampal damage will not be able to do it allocentricly but will eventually learn to do it egocentrically
what did eleanor maguire study
taxi drivers brains (in london as they has to learn all the streets off by heart)
what did eleanor maguire study find
increased posterior hippocampal volume in taxi drivers compared to normal individuals
she also found that the anterior hippocampal volume was smaller in taxi drivers
this was not associated with driving alot because she also tested bus drivers and she did not see this
