For Squire's interpretation of MTL (medial temporal lobe) amnesia:

 Amnesia reflects a particular type of impairment in which kind of memory?   What 2 types of memories cannot be formed?

What is the critical factor this impairment depends on?

For Squire's interpretation of MTL (medial temporal lobe) amnesia:

 Amnesia reflects a particular type of impairment in which kind of memory?   What 2 types of memories cannot be formed?

What is the critical factor this impairment depends on?

- declarative memory

- inability to form new memories for facts or events

- depends critically on conscious awareness

In Squire's interpretation of MTL amnesia:

 what specifically about new declarative memories is impaired?

In Squire's interpretation of MTL amnesia:

 what specifically about new declarative memories is impaired?

consolidation of new declarative memories

In Squire's interpretation of MTL amnesia:

What is the status of non-declarative memories?

What is the role of MTL regions in conscious retrieval of remotely acquired declarative memories?

In Squire's interpretation of MTL amnesia:

What is the status of non-declarative memories?

What is the role of MTL regions in conscious retrieval of remotely acquired declarative memories?

- non-declarative memories are intact

- MTL regions are NOT requried for retrieval of remotely acquired declarative memories

What does it mean that retrograde amnesia is "temporally graded" ?

What has this been interpreted to mean?

What does it mean that retrograde amnesia is "temporally graded" ?

What has this been interpreted to mean?

- older memories are better preserved

- taken to mean that memories become independent of the hippocampus over time

In Squire's Consolidation Theory (1984/1989), what is the difference between associative binding and consolidation?

- associative binding is where different memory components from the neocortex form connections with each other through the MTL, during learning

- Consolidation is the formation of connections directly between the cortical areas along w/ decrease in cortical-MTL connections -- occurs over period of years

In consolidation theory, what is the role of the MTL after consolidation?

The theory explains why amnesics can ______________...

but cannot _________________.....

In consolidation theory, what is the role of the MTL after consolidation?

- none

The theory explains why amnesics can retrieve remote (old) memories

but cannot form new long-term declarative memories

Principles of Consolidation Theory: 1

 Which brain structure binds cortical representations via the medial temporal cortex?

What types of relationships does binding allow to be stored?

What type of memory is this known as?

Principles of Consolidation Theory: 1

 Which brain structure binds cortical representations via the medial temporal cortex?

What types of relationships does binding allow to be stored?

What type of memory is this known as?

- hippocampal complex

- spatial, temporal, reward, etc. relationships btwn different cortical representations

- relational memory

Principles of Consolidation Theory: 2

Recalling a long-term declarative memory initially relies on which brain structure?

What does this structure do in order to recall the memory?

Principles of Consolidation Theory: 2

Recalling a long-term declarative memory initially relies on which brain structure?

What does this structure do in order to recall the memory?

-  the hippocampus

- it simultaneously reactivates the same cortical representations that were activated during encoding

What is the example about rats that was given as evidence for 'binding' ?

 rats with hippocampal damage are not able to take a direct path to the platform in the Morris water maze; their paths look like they just wander around

What was the example given about humans as evidence in support of binding?

 normal humans: if show them the 'same' picture twice with an object missing from the 2nd picture, people look where the item previously was even if they have no conscious knowledge that the picture is any different than the first...

but,

amnesics do not show this relational memory effect

Describe Chun & Phelps (1999) study on Contextual Cuing

(related to Consolidation theory, binding).

Describe Chun & Phelps (1999) study on Contextual Cuing

(related to Consolidation theory, binding).

- Task: search for 'T' among 'L' distractors; push button indicating if orientation of 'T' is rotated left or rotated right.

- Some T/L patterns are repeated... controls but not amnesics show RT improvement for the repeats, though neither group remembers seeing it before

- this result, that a long-term declarative memory can be used w/o conscious awareness, conflicts w/ Squire's view that decl.  mem. depends on conscious awareness

What conclusion did Wheeler's (2000) study reach regarding brain activity during recall?

- recall involves reactivating cortical regions involved in encoding an event

What is the problem with Standard Consolidation Theory's claim that long-term memories eventually are purely cortical-cortical connections with no role for the MTL?

-- some retrograde amnesics can't remember memories as old as 20-30 years... how long can consolidation possibly take?!

--  some recent studies show increased MTL activity during retrieval of remote memory

What is the problem with Standard Consolidation Theory's claim that consolidation is critical for 'declarative memory' ?

 some amnesics have worse retrograde amnesia for episodic memory than semantic memory, which indicates that not all declarative memory functions in the same way and must be studied differently

Another problem with Standard Consolidation Theory is dissociations between which two kinds of declarative memory?

recollection vs. familiarity

For dissociation between recollection/familiarity, which of the 2 is sometimes spared in patients w/ focal hippocampal damage?

 What have imaging studies shown about the hippocampus during these 2 memory tasks?

Is this in line with Squire's view?

For dissociation between recollection/familiarity, which of the 2 is sometimes spared in patients w/ focal hippocampal damage?

 What have imaging studies shown about the hippocampus during these 2 memory tasks?

Is this in line with Squire's view?

- recognition is sometimes spared despite impaired recall

- img studies: hippocampus increases during recollection but rarely during recognition

- against Squire's view which claims ALL forms of declarative memory formation and consolidation are equally dependent on ALL subregions of the MTL

Whose study showed that the hippocampus is activated for recollection but not familiarity? Give a brief summary.

Whose study showed that the hippocampus is activated for recollection but not familiarity? Give a brief summary.

- Eldrige (1999)

-  study word lists, then given test words and indicate if remember seeing the word, know they saw the word, or didn't see the word

- hippocampus activated during correct 'remember' judgments but not during correct 'know' judgments

What did Ranganath's (2004) study conclude, is recollection just a high degree of familiarity, or not?

(& what brain activity evidence was obtained to support this)

What did Ranganath's (2004) study conclude, is recollection just a high degree of familiarity, or not?

(& what brain activity evidence was obtained to support this)

-  no it is not, it's a different concept:

- increasing familiarity correlated with increased encoding activity in the entorhinal cortex but not in the hippocampus

What inherent difference between recollection and familiarity makes sense in light of the idea that the hippocampus is for relational memory?

 - recollection requires recalling how objects & events related to each other (context) but familiarity only requires recalling that an item was seen before (independent of its context).

What evidence from recent brain imaging studies directly contradict Squire's Standard Consolidation Theory?

- the MTL is active during retrieval of remote memories, as well as recent autobiographical memories

Describe the role given to the MTL in consolidation in Multiple Trace Theory, a newer alternative to Consolidation Theory.

- no new cortical representations or connections are formed, but existing ones form more and more connections to the MTL every time an episodic memory is retrieved

What does Multiple Trace Theory predict about the relation between episodic memories and hippocampal damage?

 About the retrograde amnesia deficits that MTL patients should have?

What does Multiple Trace Theory predict about the relation between episodic memories and hippocampal damage?

 About the retrograde amnesia deficits that MTL patients should have?

-  the more times an episodic memory is retrieved, the more resistant it should be to hipp. damage

- deficit should be less pronounced for remote memories that have been retrieved multiple times

Who proposed the idea of 'binding' at the cellular level?

Donald Hebb

What is binding at the cellular level?

 when a pre-synaptic & post-synaptic cell fire together the synapse is strengthened

dorky way: 'fire together, wire together'

what objective measure is used to show that long-term potentiation of synaptic connections is caused by firing of pre-synaptic pathways? (ie, what do you measure to prove that fire together = wire together)

the EPSP (in mV) of a pathway in response to a stimulus is higher after artificially stimulating the pre-synaptic pathway compared to the EPSP before manipulating the neurons

What are the molecular/cellular level steps for LTP?

- presynaptic cell releases glutamate, binds to NMDA receptor on post-synaptic cell

- Mg2+ ion moves & unblocks the Ca 2+ ion channel

- influx of calcium activates AMPA receptors on the dendrites or causes creation of new ones

- can also cause gene expression that causes long-term change in synaptic connections

Associative LTP allows binding of multiple sources of information.  How/why does strong stimulation from a given pre-synaptic pathway make LTP possible for other, weaker pre-synaptic pathways?

 - the EPSPs from the strong pre-synaptic input pathway travel down the dendrite causing strong enough depolarization to unblock NMDA channels of nearby incoming synapses (from other input pathways)

- Ca2+ can still enter post-syn. cell and cause LTP

How were knockout mice used to show the importance of LTP for relational memory?

 mice w/ knocked out NMDA receptors can't learn location of platform in Morris Maze