Associative Learning Increases Trial-by-Trial Similarity of BOLD-MRI Patterns

http://www.jneurosci.org/content/31/33/12021.full.pdf+html

 

Associative Learning Increases Trial-by-Trial Similarity of BOLD-MRI Patterns

 

Rene´e M. Visser,

1,2

H. Steven Scholte,

2,3

and Merel Kindt

1,2

1

Department of Clinical Psychology,

2

Priority Program Brain and Cognition, and

3

Department of Brain and Cognition, University of Amsterdam,

1018 WB Amsterdam, The Netherlands

Associative learning is a dynamic process that allows us to incorporate new knowledge within existing semantic networks. Even after

years, a seemingly stable association can be altered by a single significant experience. Here, we investigate whether the acquisition of new

associations affects the neural representation of stimuli and how the brain categorizes stimuli according to preexisting and emerging

associations. Functional MRI data were collected during a differential fear conditioning procedure and at test (4 –5 weeks later). Two

pictures of faces and two pictures of houses served as stimuli. One of each pair coterminated with a shock in half of the trials (partial

reinforcement). Applying Multivoxel Pattern Analysis (MVPA) in a trial-by-trial manner, we quantified changes in the similarity of

neural representations of stimuli over the course of conditioning. Our findings show an increase in similarity of neural patterns throughout the cortex on consecutive trials of the reinforced stimuli. Furthermore, neural pattern similarity reveals a shift from original categories (faces/houses) toward new categories (reinforced/unreinforced) over the course of conditioning. This effect was differentially

represented in the cortex, with visual areas primarily reflecting similarity of low-level stimulus properties (original categories) and

frontal areas reflecting similarity of stimulus significance (new categories). Effects were not dependent on overall response amplitude

and were still presentduring follow-up. We conclude thattrial-by-trial MVPA is a useful tool for examining how the human brain encodes

relevant associations and forms new associative networks.

 

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Lee de-Wit (PhD), Post-Doctoral Researcher

Gestalt ReVision Project, University of Leuven.

https://sites.google.com/site/leehdewit/

http://ppw.kuleuven.be/labexppsy/gestaltrevision/

lee.dewit@psy.kuleuven.be, ++32 16 326 143

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