9b. memory - the medial tempopral lobe

define episodic memory - tulving

re-experiencing an event, with what, where and who information

like mental time travel

what structures are in the medial temporal lobe

hippocampus, amygdala, parahippocampal cortex, fornix etc

name and explain the two types of amnesia

retrograde amnesia - inability to recall memories from before amnesia

anterograde amnesia - inability to make new memories after amnesia

what is korsakoff’s syndrome

amnesia that comes from long-term alcoholism

explain what happened with patient HM

had a bilateral medial temporal lobectomy to fix his severe epilepsy

had minor retrograde amnesia (2 years prior to surgery) and severe anterograde amnesia (complete inability to form new long term memories)

what was patient HMs implicit and explicit memory like

implicit memory still intact

explicit memory impaired

what area of the brain does activity predict later remembering stimuli

left ventrolateral prefrontal cortex and left medial temporal lobe

explain how dual process and recognition memory works - familiarity and recollection

the perirhinal cortex processes item representations - key for familiarity

the hippocampus binds items to context - key for recollection

define consolidation

the process of turning new fragile memories into more permanent versions

define reconsolidation

when a consolidated memory re-establishes itself after being reactivated by reminders

it is vulnerable to disruption here

define synaptic consolidation

structural changes in synaptic connection between neurons

define system consolidation

the gradual shift of a memory from the hippocampus to the neocortex

explain Ribot’s law

memory loss after brain damage has a temporal gradient

more recent memories are more likely to be lost than older ones

this is because older memories have gone through system consolidation, not relying on the medial temporal lobe anymore

what happened to patient PZ

PZ was a uni lecturer who had Korsakoff’s syndrome

he was unable to learn new paired associations, remembering people from the 1930s-1940s but no one later

explain the standard consolidation model

the hippocampus binds together loads of different info from different regions of the brain

over time the hippocampus plays less of a role

explain multiple trace theory

the hippocampus is always needed to store and retrieve episodic memories, no matter how old they are

every time a memory is recalled, the brain creates a new distributed trace in the hippocampus

this explains how older memories are more likely to be remembered because they have more traces

what is trace decay

when memories weaken because of time

define context shifts

when different cues are available now than ones available at encoding

define interference

similar memories getting in the way of retrieval

name the two ways trace decay impact memories

a memory’s activations can fade, with the memory itself staying intact

or

the memory and its activations can both fade

explain the biological basis for trace decay

as time goes by, synaptic connections and neurons can die, making memories die/fade

neurogenesis (growth of new neurons) means the structure of the hippocampus is remodelled and connections are changed, changing the traces