Reduced visual and frontal cortex activation during visual working memory in grapheme-color synaesthetes relative to young and older adults

Pfeifer, Gaby, Ward, Jamie and Sigala, Natasha (2019) Reduced visual and frontal cortex activation during visual working memory in grapheme-color synaesthetes relative to young and older adults. Frontiers in Systems Neuroscience, 13 (29). pp. 1-15. ISSN 1662-5137

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Abstract

The sensory recruitment model envisages visual working memory (VWM) as an emergent property that is encoded and maintained in sensory (visual) regions. The model implies that enhanced sensory-perceptual functions, as in synaesthesia, entail a dedicated VWM-system, showing reduced visual cortex activity as a result of neural specificity. By contrast, sensory-perceptual decline, as in old age, is expected to show enhanced visual cortex activity as a result of neural broadening. To test this model, young grapheme-color synaesthetes, older adults and young controls engaged in a delayed pair-associative retrieval and a delayed matching-to-sample task, consisting of achromatic fractal stimuli that do not induce synaesthesia. While a previous analysis of this dataset (Pfeifer et al., 2016) has focused on cued retrieval and recognition of pair-associates (i.e., long-term memory), the current study focuses on visual working memory and considers, for the first time, the crucial delay period in which no visual stimuli are present, but working memory processes are engaged. Participants were trained to criterion and demonstrated comparable behavioral performance on VWM tasks. Whole-brain and region-of-interest-analyses revealed significantly lower activity in synaesthetes’ middle frontal gyrus and visual regions (cuneus, inferior temporal cortex), respectively, suggesting greater neural efficiency relative to young and older adults in both tasks. The results support the sensory recruitment model and can explain age and individual WM-differences based on neural specificity in visual cortex.

Item Type: Article
Keywords: synaesthesia, ageing, fMRI, working memory, associative memory
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
School of Psychology > Psychology
Research Centres and Groups: Sackler Centre for Consciousness Science
Subjects: Q Science > QZ Psychology
Related URLs:
Depositing User: Natasha Sigala
Date Deposited: 11 Jul 2019 12:22
Last Modified: 11 Jul 2019 12:30
URI: http://sro.sussex.ac.uk/id/eprint/84835

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