psych 345 lecture 21 - memory and amnesia II

what are the 2 components of LTM?

1. explicit memory

2. implicit memory

explicit memory and the 2 types

explicit memory = the consciously retrievable memories that connect an experience with rich sensory details

1. episodic memory

2. semantic memory

episodic memory

a persons recall of specific events, personal life experiences and life history — very detailed and rich with context — lke episodes of your life

semantic memory

general knowledge and facts about the world — information learned in school (facts not context)

implicit memory and its 1 subcategory

unconscious, automatic memory expressed through behavior, not conscious recall

1. procedural memory

procedural memory

memory for skills and procedures (riding a bike, driving, playing an instrument)

why can amnesic patients learn new skills?

procedural memory is implicit and does NOT rely on explicit recall so amnesics can still learn new habits and skills

priming

an implicit memory process where prior exposure to information unconsciously influences later behavior by activating stored representation

how does priming affect behavior?

it makes previously encountered information faster and easier to access in a new context

name the 4 components of the structural explicit memory

1. encoding

2. consolidation

3. long-term storage

4. retrieval

encoding + role of PFC

the PFC works with the hippocampus and medial temporal lobe (MTL) to organize incoming information and the PFC decides what you pay attention to and how that information is structured before storage

consolidation + its critical component

the hippocampus + MTL structure stabilizes the memory trace over time taking hours, days, or years

the hippocampus is critical here

long-term storage

LTM is stored across the cortex, especially in the same sensory areas that were active during the experience

true or false: LTM occurs in the hippocampus

false!

retrieval

the PFC helps with conscious recall, strategic search, cues, and monitoring accuracy

how is the hippocampus involved in retrieval?

the hippocampus/MTL helps retrieve memories only before they are fully consolidated, AFTER consolidation memory is less reliant on the hippocampus and is more cortex-based

name the 4 medial temporal lobe (MTL) structures in memory

1. perirhinal and parahippocampal cortex

2. entrorhinal cortex

3. hippocampus

4. amygdala

perirhinal cortex

important for object memory and recognizing what something is, supporting familiarity judgements

parahippocampal cortex

important for the context and spatial memory, where something is

entorhinal cortex

the major gateway between cortex and hippocampus intergrating what + where info before sening it to the hippcampus

hippocampus

critical for forming new explicit memories

the prefrontal cortex (PFC) is key for what?

encoding (attention, organization) and retrieval (conscious search, monitoring, selecting correct memory)

what are the 3 things the hippocampus NOT required for

1. strategic processes

2. long-term memory storage

3. post-consolidation memory

the amygdala does what?

modulates memory strength based on emotion

emotional arousal leads to stronger ____

consolidation

what are the 3 components of our memory circuitry?

1. basal forebrain circuit

2. medial thalamus circuit

3. medial temporal lobe circuit (including the hippocampus)

acetylcholine

one of the most important neurotransmitters for learning, attention, and memory

true or false: acetylcholine is its own memory circuit

false! acetylcholine is NOT a memory circuit on its own, it is the chemical messenger that powers the circuits below and keeps them functioning properly

amnesia

the neuropsychological condition in which memory is disturbed or lost

what are the two categories of amnesia?

1. retrograde

2. anterograde

retrograde amnesia

the loss of memories for event prior to damage (less common)

what is the temporal gradient

earlier memories are remembered better than recent ones because recent memories were not fully consolidated

why does retrograde amnesia stay steady over time?

trick question: it doesnt! retrograde amnesia often shrinks over time because memories were not destroyed just temporarily innaccessible

true or false: retrograde amnesia mainly affects retrieval but can sometimes affect consolidation

true!

anterograde amnesia

the inability to form new long-term memories after head injury; failure of encoding + consolidation (more common)

what kinds of memory are impaired in anterograde amnesia?

new episodic memories and sometimes new semantic memories

what part of memory is intact in anterograde amnesia

working/stm

what happens with hippocampal-only lesions?

episidoc memory is impaired while semantic memory and procedural skills are spared

what happens when lesions extend into the surrounding MTL cortex (entorhinal, perirhinal, parahippocampal)?

impair both episodic and semantic memory —> global explicit memory deficits

why cant people with anterograde amnesia form new long-term memories

because anterograde amnesia leads to a deficit in encoding, consolidation, and storage of new information