Open AccessDissociating Representations of Time and Number in Reinforcement-Rate Learning by Deletion of the GluA1 AMPA Receptor Subunit in Mice
Author(s) -
Joseph M. Austen,
Corran Pickering,
Rolf Sprengel,
David J. Sanderson
Publication year - 2021
Publication title -
psychological science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.641
H-Index - 260
eISSN - 1467-9280
pISSN - 0956-7976
DOI - 10.1177/0956797620960392
Subject(s) - reinforcement , psychology , ampa receptor , encoding (memory) , reinforcement learning , associative property , associative learning , weighting , protein subunit , neuroscience , cognitive psychology , receptor , social psychology , genetics , nmda receptor , artificial intelligence , biology , gene , mathematics , computer science , medicine , radiology , pure mathematics
Theories of learning differ in whether they assume that learning reflects the strength of an association between memories or symbolic encoding of the statistical properties of events. We provide novel evidence for symbolic encoding of informational variables by demonstrating that sensitivity to time and number in learning is dissociable. Whereas responding in normal mice was dependent on reinforcement rate, responding in mice that lacked the GluA1 AMPA receptor subunit was insensitive to reinforcement rate and, instead, dependent on the number of times a cue had been paired with reinforcement. This suggests that GluA1 is necessary for weighting numeric information by temporal information in order to calculate reinforcement rate. Sample sizes per genotype varied between seven and 23 across six experiments and consisted of both male and female mice. The results provide evidence for explicit encoding of variables by animals rather than implicit encoding via variations in associative strength.