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The Neural Basis Of Amnesia 2 Lec 4 Notes

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This is an extract of our The Neural Basis Of Amnesia 2 Lec 4 document, which we sell as part of our Neuropsychology of Memory Notes collection written by the top tier of Durham University students.

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The Neural Basis of Amnesia (2) Episodic Memory??Tulving (1972) first coined the phrase ? ability to remember personally experienced events - what, where and + when an event occurred Tulving (1983) elaborated original definition - proposed that EM necessarily depends upon autonoetic awareness (conscious reexperiencing of an event)
- Machphail (1998) - also maintained that consciousness is a crucial prerequisite for all forms of explicit memory This def present major problems - impossible to demonstrate pure EM in animals as they cannot communicate consciousness through language (Griffiths et al., 1999) This issue been resolved to an extent through the introduction of the term episodic like memory (ELM) ? has all the characteristics of EM - what, where + when and event took place - with the exception that there is no requirement to demonstrate autonoetic awareness (Clayton & Dickinson, 19898) - therefore can study in animals Tulving (1983)
- EM = memory which ? "receives + stores info about temporally dated episodes or events (what), and temporal-spatial relations (where-when) between them" RECALL V FAMILIARITY

? Episodic memory is declarative in nature - it involves calling to mind +
recalling the specific event
? Changes in behaviour caused by previous experience does not need episodic memory e.g. - procedural learning - same may be said for recognition memory based on familiarity - remembering something merely because it is familiar Aggleton & Brown (2006)??Recent findings reinforce the view that recognition memory comprises at least 2 independent processes -> one recollective + other using familiarity detection ? Only recollective recognition seems to depend on episodic memory Investigated the crucial issue of whether episodic + recognition memory reflect the same underlying processes + extent to which certain brain structures work as a single unit to support these processes Attempts to find the neural basis of these functions indicate that these two components depend on separate but interlinked structures Authors support two-process models of recognition that allocate different processes to separate but different, interconnected, brain structures. THERE ARE TWO SEPARATE COMPONENTS OF RECOGNITION MEMORY (FAMILIARITY + RECOLLECTIVE) - THESE HAVE DIFFERENT NEURAL SUBSTRATES

? Recall/recollection = hippocampus + anterior thalamus
? Familiarity = perirhinal + parrahippocampal cortex + medial dorsal thalamus

Evidence for this:Event related potentials
- 2 different anatomical populations have been identified that are functionally + temporally dissociable
- First pop = indexed by activity over the frontal scalp from 300500ms post stimulus -? neural correlate of familiarity
- Second pop = evident over the parietal scalp from 500-800ms post stimulus + might index recollection fMRI
- number of fMRI studies support dual processing accounts of recognition memory because dissociable patterns of activity are found for measures of familiarity + recollection
- Increased hippocampal activity has been correlated with reports of recollection of the learning episode but not with familiarity
- Some research has linked hippocampal activity with recollection but anterior parahippocampal cortex activity with familiarity

The MTLMS doesn't contain just one memory circuit (Squire)- but two components Suggested that episodic memory is recall based + semantic memory is familiarity based:

Episodic (Recall)??Events are "remembered" Organised temporally Succeptible to forgetting Context dependent - scenes

Semantic (Familiarity)??

Events are familiar "known" Not temporally organised Relatively permenant Not context dependent
- no scenes

? Hippocampus + surrounding cortex has become known as the medial temporal lobe memory system (MTLMS) If familiarity based judgements reside in the parahippocampal + perirhinal cortex + recall judgements reside in the hippocampus ? what happens when you lesion the surrounding cortex (means they cannot use familiarity
- semantics to solve the DMTS task) ? Eacott, Gaffan & Murray (1994)

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