Dit is het vak Cognitive Neuroscience van UU. Deze documenten gaan over deel 2 van de cursus, dus deeltentamen 2. Het is met name gefocust op de meest belangrijke stof uit de hoorcolleges de meest relevante informatie uit het boek. Het is dus geen samenvatting van het hele boek, maar de relevant...
Memory
A series or processes whereby the nervous system acquires inrormaton rrom new experience,
retains this inrormaton over tme and eventually uses it to guide behavior and plan ruture actons.
- Retrieval: accessing stored memory traces
- Storage: the retenton or memory traces over tme. Long-term retenton requires cell-and
system-level stabilizaton.
- Encoding: the processes whereby experiences can alter the nervous system.
- Learning: the combined efect or retrieval, storage and encoding in gradually enhancing the
perrormance or a partcular tasks.
- Working memory: the maintenance and manipulaton or inrormaton online ror a rew
seconds.
All varietes or memory appear to depend on the same cellular and molecular mechanisms or neural
plastcity. At cellular level, memories are transiently stored as changes in the efcacy or existng
synaptc connectons between neurons within partcular neuronal assemblies. Longer-lastng
memories require more permanent changes in gene expression, protein synthesis and morphology,
including transrormaton or new synaptc connectons.
Brain mechanisms of learning and memory
What is happening in the brain during learning and memory rormaton and where does it occur?
An important concept in cognitve neuroscience is the one or representatons.
Churchland and Sejnowski
Defning runcton or nervous systems is representatonal. The inrormaton is stored in the brain. rain
states represent states or some other system, the outside world or the body itselr. Transitons
between states can be explained as computatonal operatons on representatons.
Churchland
,Representatons that are happening now are paterns or actvaton or neurons in a networks. Stored
representatons, so memory, are believed to depend on the confguraton or weights between units.
Somehow the connecton between those units has something to do with memory. In neural terms,
these weights are the strength or synaptc connectons between neurons. Changes in these weights
give the representaton.
What happens in the brain
Tanzi(1893) and Hebb(1949)
An alteraton in the efectveness or existng connectons. A networks or neurons are all connected
with each other and there are changes in the existng networks.
Cajal(1894)
The rormaton or new connectons between neurons
They all agree that structural changes in neuronal connectvity are happening in the brain, at the
level or synapse.
Synaptc strength: more post-synaptc receptors that can pass on a signal or more neurotransmiter is
released rrom the pre-synaptc membrane.
Where in the brain do these changes occur
Lashley
Rats and mazes.
Rats had to walks through a maze. The more ofen they did it, the raster they could do it. He examined
the parts or the brain that had something to do with the memory or the rats. Knire cuts in the brains
or the rats and see ir they could stll do the tasks.
The bigger the lesion he made the bigger the efect was. ut it didn’t mater where he made the
lesion.
Human amnesia
Memory loss
Damage to the temporal lobe
Patent HM.
He sufered rrom a serious rorm or epilepsy. He was operated in 195c7 and parts or his temporal lobes
were removed.
The lesion was bilateral. So part or the uncus, hippocampus and hippocampal gyrus were removed.
Also rrom the entorhinal cortex: the amygdala.
He wasn’t epileptc anymore, but he had memory problems. He was unable to remember post-
surgery events. His short term memory was intact, so he could remember inrormaton ror a brier
period or tme.
His declaratve memory was impaired but not his worksing memory.
,Damage to the diencephalon
Patent NA. was accidentally stabbed with a miniature rencing roil. It went through his eye into his
brain. There was damage to the diencephalon. He also had memory loss.
Korsakov
The result or a lacks or thiamine, so vitamin 1. It ofen occurs among alcoholics, who are
malnourished and have a lacks or vitamin 1. These peoples have anterograde and retrograde
amnesia, so they have very bad memory rrom the past. Also they tend to confabulate: they are
maksing up stories about their past.
Most or the tme it is caused by damage to the dorsomedial nucleus or the thalamus and the
mammillary bodies.
Forms of Amnesia
1. Anterograde amnesia: amnesia ror events after surgery/trauma
2. Retrograde amnesia: the amnesia goes backs into the short past, but not the older past.
Amnesia ror events before surgery/trauma.
Amnesia due to brain lesions most ofen arises rrom bilateral damage to the medial temporal lobe.
Unilateral damage produces relatvely mild memory defcits.
Intact functons with amnesia patentssnot always)
, - Declaratve memory impaired: the memory that you can say something about. The way you
tooks to get somewhere.
- Procedural memory: the sksills, simple rorms or conditoning, priming. This one is ofen intact.
Memory systems
Semantc dementa: people rorget about certain things. It contains racts.
Non-declaratie/implicit memory
The memories that are expressed through perrormance independently or consciousness.
Patents with damage can do things very well but they cannot tell you about it. There is a memory or
the event, but it is an implicit memory. A patent cannot really say what it is
With damage to the implicit memory or with damage to the explicit memory? So declaratve memory
or non-declaratve?
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