Remerge a new approach to the neural basis of generalization and memory based inference
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REMERGE: A new approach to the neural basis of generalization and memory-based inference. Dharshan Kumaran , UCL Jay McClelland, Stanford University. Medial Temporal Lobe. Proposed Architecture for the Organization of Semantic Memory McClelland, McNaughton & O’Reilly, 1995. name. action.

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Remerge a new approach to the neural basis of generalization and memory based inference

REMERGE: A new approach to the neural basis of generalization andmemory-based inference

DharshanKumaran, UCL

Jay McClelland, Stanford University


Proposed architecture for the organization of semantic memory mcclelland mcnaughton o reilly 1995

Medial Temporal Lobe generalization and

Proposed Architecture for the Organization of Semantic MemoryMcClelland, McNaughton & O’Reilly, 1995

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action

motion

Temporal

pole

color

valance

form


Two questions
Two Questions generalization and

  • If extraction of generalizations depends on gradual learning, how do we form generalizations and inferences shortly after initial learning?

  • Why do some studies find evidence consistent with the view that an intact MTL facilitates certain types of generalization in memory?


Relational theory of memory eichenbaum cohen
Relational Theory of Memory ( generalization andEichenbaum & Cohen)

  • Proposes that elements of related memories become linked within the same memory trace, and that the formation of such linkages is a critical function of the MTL.


Remerge recurrence and episodic memory results in generalization
REMERGE: Recurrence and Episodic Memory Results in Generalization

  • Holds that several MTL based item representations may work together through recurrent activation

  • Draws on classic exemplar models (Medin & Shaffer, 1978; Nosofsky, 1984)

  • Extends these models by allowing similarity between stored items to influence performance, independent of direct activation by the probe (McClelland, 1981)

  • Demonstrates the strong dependence of some forms of generalization and inference on the strength of learning for trained items


Phenomena considered
Phenomena Considered Generalization

  • Benchmark Simulations

    • Categorization

    • Recognition memory

  • Acquired Equivalence

  • Associative Chaining

    • In paired associate learning

    • In hippocampal reactivation during sleep

  • Transitive Inference

    • Effects of increasing study

    • Effects of sleep


Acquired equivalence shohamy wagner 2008
Acquired Equivalence Generalization(Shohamy & Wagner, 2008)

  • Study:

    • F1-S1;

    • F3-S3;

    • F2-S1;

    • F2-S2;

    • F4-S3;

    • F4-S4

  • Test:

    • Premise: F1: S1 or S3?

    • Inference: F1: S2 or S4?


Acquired equivalence shohamy wagner 20081
Acquired Equivalence Generalization(Shohamy & Wagner, 2008)

  • Study:

    • F1-S1;

    • F3-S3;

    • F2-S1;

    • F2-S2;

    • F4-S3;

    • F4-S4

  • Test:

    • Premise: F1: S1 or S3?

    • Inference: F1: S2 or S4?

F1 S1 F2 S2 F3 S3 F4 S4


Acquired equivalence shohamy wagner 20082
Acquired Equivalence Generalization(Shohamy & Wagner, 2008)

S1 S2 S3 S4

  • Study:

    • F1-S1;

    • F3-S3;

    • F2-S1;

    • F2-S2;

    • F4-S3;

    • F4-S4

  • Test:

    • Premise: F1: S1 or S3?

    • Inference: F1: S2 or S4?

F1 S1 F2 S2 F3 S3 F4 S4


Acquired equivalence shohamy wagner 20083
Acquired Equivalence Generalization(Shohamy & Wagner, 2008)

S1 S2 S3 S4

  • Study:

    • F1-S1;

    • F3-S3;

    • F2-S1;

    • F2-S2;

    • F4-S3;

    • F4-S4

  • Test:

    • Premise: F1: S1 or S3?

    • Inference: F1: S2 or S4?

F1 S1 F2 S2 F3 S3 F4 S4


Acquired equivalence shohamy wagner 20084
Acquired Equivalence Generalization(Shohamy & Wagner, 2008)

  • Study:

    • F1-S1;

    • F3-S3;

    • F2-S1;

    • F2-S2;

    • F4-S3;

    • F4-S4

  • Test:

    • Premise: F1: S1 or S3?

    • Inference: F1: S2 or S4?


Associative chaining
Associative Chaining Generalization

  • Study:

    • AB, XY

    • BC, YZ

  • Test:

    • A: B or Y

    • A: C or Z

A B C X Y Z


Hippocampal reactivation after maze exploration
Hippocampal Generalization Reactivation After Maze Exploration

Replays in Remerge:

Forward: 51%

Backward: 31%

Crossed: 18%

Disjoint: <1%



Discussion
Discussion Generalization

  • As we’ve known for quite some time

    • Generalization and Inference can be supported by exemplar models

  • Should we, then, simply abandon the complementary learning theory, and just make it exemplars all the way down?

  • I think not –

    • Cortical learning supports changes in the ‘features’ that serve as the basis for exemplar learning

    • And clearly, retrograde amnesia studies support = an MTL basis for recent memory= a neocortical basis for remote memory

  • A future challenge is to develop an fully integrated neuro-computational theory of memory integrating MTL and neocortical influences


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