Long Term Memory

Declarative/Explicit Memory Definition

memories that can be consciously accessed and therefore typically declared

Two types of memory that are declarative

episodic and semantic

Non-declarative/Implicit Memory Definition

memories that cannot be consciously accessed

What type of memory is considered non-declarative?

procedural

Episodic memory

memory for specific events in one’s life (autobiographical)

Semantic memory

conceptual knowledge about the world; people, places, meanings

Procedural memory

memory for skills

Which brain region is important for learning procedural skills?

the basal ganglia

Global Amnesia

amnesia in both the anterograde and retrograde form

Anterograde Amnesia

the inability to learn new information

Retrograde Amnesia

the inability to remember prior knowledge

Amnesia is the biggest sign of what disease?

Alzheimer’s

What type of memory is the most affected by amnesia?

episodic memory

Wechsler Memory Scale

used to assess if one is able to learn new material like lists of words

Autobiographical Memory Interview

used to assess one's ability to recall events in their own life

Is STM impaired when one has amnesia?

typically it is not impaired

STM + Patient HM

• patient HM had his MTL removed

• could hold onto numbers for 15 minutes if her repeated and reheased these numbers

• if he stopped rehearsing, he could no longer remember the numbers or remember even being asked to learn them

STM can be affected in terms of spatial layout memory because…

because the hippocampus plays an important role in processing spaces, so damage to the hippocampus may impair one’s ability to remember spatial layouts

Is procedural memory impaired with amnesia?

procedural memory is not typically impaired

can people with amnesia learn new tasks?

yes. because procedural memory is spared, they are able to learn how to do new things but often do not remember the actual act of learning the skill

Patient HM and Procedural Memory

was asked to learn how to draw a star while looking in the mirror. as the trials went on, he got better at this skill but could not remember the actual event of learning

Is semantic memory impaired in amnesia?

semantic knowledge is often preserved, but this is often because we learn many facts and names of things at a young age

• when new semantic knowledge comes up (e.g., the name of a new celebrity) people with amnesia often cannot remember this

Consolidation Definition

the process by which moment-to-moment changes in brain activity are translated into permanent structural changes in the brain

how does consolidation occur on a neuronal level?

consolidation is the process of forming new neural connections to represent memories

Long-Term Potentiation Definition

an increase in the long-term responsiveness of a postsynaptic neuron in response to stimulation of a presynaptic neuron; the neuronal change that occurs during consolidation

Synaptic Consolidation

restructuring of local synapses as a result of changes in presynaptic neural activity; generally found throughout the brain

System Consolidation

reorganization of connectivity patterns across disparate regions (the hippocampus and neocortex) that may be related to declarative memory

• the processes of consolidation from the hippocampus to the cortex that is proposed by the standard consolidation theory

Ribot’s Law

the observation that memories from early in life tend to be preserved in amnesia

How does the standard consolidation theory explain Ribot’s Law?

Consolidation theory explains this phenomenon by assuming that older events are more consolidated and therefore less dependent on the hippocampus, and conversely newer memories still rely on the hippocampus, thus when damaged they cannot be recalled

How does the standard consolidation theory propose memories are consolidated?

• suggests that the hippocampus sends synaptic messages to the neocortex to promote consolidation

• It is suggested that this occurs by replaying memories during sleep and during relaxed wakefulness

How do patients with semantic dementia differ from patients with alzheimer’s?

patients with semantic dementia remember recent memories better than they remember distant memories; those with alzheimer’s are better at remembering distant memories

How do patients with semantic dementia give evidence towards the standard consolidation theory?

because these patients have damage in their cortex, rather than in their hippocampus. this means that new memories can be accessed via the hippocampus, but not consolidated in the cortex, and older memories that were consolidated in the cortex are now difficult to access

What are two problems with standard consolidation theory?

1. ribot’s law doesn’t actually hold if you test retrograde episodic memory in a detailed fashion; alzheimer’s patients actually do not remember contextually rich details of their life, but rather facts (semantic memory), such as where they used to live, old phone numbers, names of people they knew since childhood

2. if consolidation theory is correct, that would mean it takes decades for humans to consolidate memories, and this is not efficient

Which LTM theory is most correct?

Multiple Trace Theory

Multiple trace theory states that the hippocampus is involved in a __________ aspect of memory storage

permanent

Multiple trace theory assumes that the hippocampus is always involved in remembering what type of memories?

contextually rich memories

How do Alzheimer’s patients provide evidenxe for multiple trace theory?

since they cannot remember contextually rich details of episodic memories, this aligns with MTT. if the hippocampus is damaged, as it is in alzheimer’s then accessing detailed episodic memories would be impaired

What fMRI evidence is there for Multiple Trace Theory?

• scans have shown that the hippocampus activates in response to both distant and recent memories, showing that it is not limited in only activating during recent memories

• fMRI scans have also found that no hippocampal regions selectively respond to recent memories only

does the hippocampus activate when imagining future episodes?

yes. the hippocampus must pull different memories and expectations together to build a future image

• people with amnesia cannot do this