PSYC 365 Lecture 21 Memory consolidation

what did McGaugh's research on people with highly superior autobiographical memory (HSAM) find?

- McGaugh's group studied if HSAM ppl relied on better cognitive abilities in other areas - gave them a ton of other cognitive tests - saw HSAM doesn't come from overall better cognitive function, not just smarter than everyone else - also examined HSAM ppl's memories of actual testing episodes - found HSAM participants recalled details of their own exp way better than smth the experimenter shared - concluded HSAM involves selective recollection of personal autobiographical material -> this is their superpower!

what is multiple trace theory (MTT)?

- episodic memories ALWAYS need the hippocampus - always needed to recall it - system-wide consolidation that SCT talks most about happens with changes in the nature of the memory -> this is called semanticization - memories can become semantic memories once they're represented outside the hippocampus, so these memories don't need the hippocampus - both semantic and episodic memories can exist alongide each other, semantic doesn't have to replace episodic once consolidation happens

how does standard consolidation theory distinguish between types of explicit memory?

- it doesn't! - sees episodic memories (specific details, particular time and place) as the same as semantic memories (less context-specific, more generic, no time attached)

what is a schema?

- mental concept that tells someone what to expect from various situations - eg. know to sit down at a restaurant and wait for a menu - act as scripts that are constructed from exp across ur life - maintained in memory - filters and organizes what we encode based on past exp similar to attention - prior knowledge affects how we memorize and retain future knowledge for long-term storage - but also lets us organize events in time so we can lay down more than a static snapshot, but sensory impressions that happen like the frames of a film - eg. video of two dudes - prefacing the blurb w the announcement that the following info is about washing clothes helps us rmb more - schemas triggered close to learning improve memory

how does multiple trace theory (MTT) explain the loss of memories?

- not all lesioned patients have temporally graded amnesia - pattern of amnesia in those w lots of hippocampal lesions depends on the type of memory tested and the nature of the lesions - lesions are messy! - test of memory that involve semantic memory result in temporal gradient - relates to amount of time that's needed to complete process of transformation - will only have amnesia for recent memories that didn't get transformed, but not older ones that already underwent transformation - but tests for pure hippocampus-dependent episodic memory result in showing non-graded amnesia, doesn't matter how old the memory is

what is standard consolidation theory (SCT)?

- older theory - states memories initially depend on hippocampus, when they're laid down and recalled right after - hippocampus is only involved for a short window of time -> needed to form associations to make coherent memory and keep it for a while, not forever - these memories are later consolidated across other brain regions with time - the memory reorganizes outside of the hippocampus in neocortical structures - now the memory can be retrieved without the hippocampus

what inspired and supported the standard consolidation theory (SCT)?

- patient HM who had hippocampal lesions was shown to have amnesia that was temporally graded - he could rmb events from a long time ago, but not anything that happened in the recent past - researchers then reasoned new memories needed the hippocampus, but older memories depended on other brain regions and didn't need the hippocampus anymore

what is semanticization?

- process of pulling general knowledge out from rehearsed events - stored separately from episodic memory - requires the hippocampus to create, but doesn't need it to retrieve - without proper hippocampus, making semantic memories as an adult is super slow and takes a lot of effort -> matches what we saw with Clive Wearing

what are regions of the autobiographical memory network?

- recall autobiographical memory = episodic and semantic memory - hippocampus - medial parietal regions: precuneus, retrosplenial cortex, posterior cingulate -> midline lump imp for autobiographical and episodic memory (also imp nodes in default network) - medial PFC - medial temporal regions hooked up to the hippocampus: entorhinal cortex (tip of the ventral visual stream that directly comm to hippocampus), parahippocampal gyrus (part of ventral visual stream sensitive to scenes, not objects) - lateral temporal regions: imp for semantic memory - lateral parietal cortex

how does standard consolidation theory (SCT) explain the loss of memories?

- recent memory is vulnerable because consolidation process hasn't happened yet - so lesioning the hippocampus would wipe it out - leave enough time for consolidation --> redistribute the memory from the hippocampus to a diff brain network incl. the neocortex - these consolidated memories are more resistant to damage - lesioning the hippocampus now won't affect these old memories

according to the multiple trace theory, what is needed for semanticization?

- rehearsal! - important idea for the Bird paper - semantic memory comes from episodic memory - every semantic memory starts out as an episodic memory (normally several) - every time an old memory is retrieved, a new trace is created, which relies on the hippocampus - the repetition of this process leads to leaving multiple traces - making lots of related traces lets our brain take away the common themes -> take out the features these multiple traces share - integrate this info w our preexisting knowledge to make semantic memories that exist of the hippocampus - eg. first day to work, walk a specific path -> walk to work every day for weeks, sometimes take a diff part of the route -> then distill common features of all these walks -> produce more general knowledge that exists independently from memory of those specific walks - then able to report that u always walk to work across the athletic field then go along Main Mall

what is reinstatement?

- related to rehearsal, rehearsal involves reinstatement - describes process of brain consolidating a memory by playing the pattern of neuronal/voxel activation that represented the initial event during encoding offline at a later time point - our brain calls up the same patterns of activity from when the event first happened - proposed this is a mechanism behind semanticization - HSAM ppl rehearse their memories a lot - go over them in their heads, file them

what is highly superior autobiographical memory (HSAM)?

- watched documentary about this - for normal ppl, knowledge of public events becomes semantic knowledge - but for HSAM ppl, they tie everything that happens to an autobiographical memory, can see everything vividly thru their own eyes - perhaps that their memories don't get fully semanticized - not better learners, show avg scores on lab memory tasks not specifically for autobiographical memory (combo of both episodic and semantic) - HSAM ppl recall past in super rich details in an automatic way - don't need mneomic techniques or practise to memorize - subject to false memories as other ppl