NEURO EXAM 4: memory and the hippocampus

what 2 broad categories can the human memory be divided into

declarative and non-declarative

declarative memory

includes your conscious recollection of previous experience (i.ei what happened to you where and when, known as episodic memory)

episodic memory

what happened to you where and when

non-declarative memory

includes learned motor skills (i.e. so-called muscle memory, known as procedural memory)

procedural memory

so-called muscle memory

what kind of memory (declarative or non declarative(procedural) is this: things you know that you can tell others

declarative

what kind of memory (declarative or non declarative(procedural) is this: things you know that you can show by doing

non declarative (procedural)

is declarative memory explicit or implicit?

explicit- you can describe the contents of memory using language

is non-declarative memory explicit or implicit

implicit- it is difficult to describe the contents using language

when accessing declarative memory, you are aware of….

the fact that you are engaged in a process of remembering

when accessing implicit memory it seems more….

automatic, to the extent that you dont feel as if youre using memory at all

amnesia

a strong memory impairment

retrograde amnesia

a loss of previously acquired memories

anterograde amnesia

inability to form new memories

what can cause retrograde amnesia

a blow to the head

what kind of amnesia does this sound like: the memory of the event itself is lost, as well as a brief period leading up to it?

retrograde

what kind of amnesia is the early stages of dementia often categorized by

anterograde but then followed by retrograde amnesia

what amnesia follows Ribot’s law

retrograde

Ribot’s law

newer memories are less resistant to disruption than older ones. So memories just prior to the onset of dementia are lost before childhood memories

who is the most studied amnesia patient in medical history

Patient HM( Henry molaison, 1926-2008)

how did patient HM get amnesia

-experienced debilitating seizures starting at 16

-had surgery to remove epileptic foci (point of origin for his seizures) at 27

-surgeoun removed medial temporal lobe, including hippocampus

-epilespy was cured, but he was left with profound memory impairments

what did Brenda Milner find in HM

-shallow retrograde amnesia with intact long-term episodic memory- HM’s memory of childhood and young adulthood remained in place

-intact short-term episodic memory- HM could remember what happened to him a few moments ago

-profound anterograde amnesia: following surgery he couldn’t form new long-term episodic memories.

what happened everyday that Milner worked with patient HM for years

everyday she met him she had to introduce herself

what are HM’s problems explain day

a consolidation deficit

why Is HM’s memory deficits caused by consolidation deficit?

-the surgery disrupted memories still in process of consolidation, hence the shallow retrograde amnesia

-the surgery prevented the consolidation of new long term memories, hence the inability to form anything other than a short term trace

what is the role of the hippocampus in episodic memory

temporary, once a memory has been consolidated, hippocampus has no role

where is permanent memory storage distributed across

cortex

what guides the process of permanent memory storage and drops out once the process is complete

hippocampus

replay

when hippocampus recreates patterns of brain activity that occurred during experience

how does the hippocampus guide and drop out of permanent memory storage

replay

what has hippocampus and cortical replay been observed in in animals

REM and Non-REM (specifically slow-wave) sleep

what does activation of hippocampus neurons during replay thought to drive

activity of cortical neurons, gradually strengthening the connections between them, in order to consolidate a memory

what idea does Bechara and colleagues back up

multiple memory systems

what did Bechara and colleagues demonstrate in their research

that conscious recollection of a scary event (ie episodic memory, explicit) and the aversive associations between stimuli (implicit) encountered during that event are processed separately in the brain

what does damage to the hippocampus prevent

formation of an episode w

what does damage to the amygdala prevent

formation of an aversive association

what part of memory was complexity intact in HM

procedural memory(ability to acquire ew and complex moot skills) /form of non-declarative memory