TY  - JOUR
A1  - Ehrlich, Isabelle
A1  - Ortiz-Tudela, Javier
A1  - Tan, Yi You
A1  - Muckli, Lars
A1  - Shing, Yee Lee
T1  - Mnemonic but not contextual feedback signals defy dedifferentiation in the aging early visual cortex
T2  - Journal of neuroscience
N2  - Perception is an intricate interplay between feedforward visual input and internally generated feedback signals that comprise concurrent contextual and time-distant mnemonic (episodic and semantic) information. Yet, an unresolved question is how the composition of feedback signals changes across the lifespan and to what extent feedback signals undergo age-related dedifferentiation, that is, a decline in neural specificity. Previous research on this topic has focused on feedforward perceptual representation and episodic memory reinstatement, suggesting reduced fidelity of neural representations at the item and category levels. In this fMRI study, we combined an occlusion paradigm that filters feedforward input to the visual cortex and multivariate analysis techniques to investigate the information content in cortical feedback, focusing on age-related differences in its composition. We further asked to what extent differentiation in feedback signals (in the occluded region) is correlated to differentiation in feedforward signals. Comparing younger (18–30 years) and older female and male adults (65–75 years), we found that contextual but not mnemonic feedback was prone to age-related dedifferentiation. Semantic feedback signals were even better differentiated in older adults, highlighting the growing importance of generalized knowledge across ages. We also found that differentiation in feedforward signals was correlated with differentiation in episodic but not semantic feedback signals. Our results provide evidence for age-related adjustments in the composition of feedback signals and underscore the importance of examining dedifferentiation in aging for both feedforward and feedback processing.
KW  - aging
KW  - dedifferentiation
KW  - feedback
KW  - memory
KW  - predictive processing
KW  - visual cortex
Y1  - 2024
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/85704
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-857046
SN  - 0270-6474
VL  - 44
IS  - 16  e0607232023
PB  - Society for Neuroscience
CY  - Washington, DC
ER  -