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Contrasting semantic and domain-general control: The semantic control network is preferentially activated for the control of meaningful verbal and nonverbal stimuli
Poster Session B, Wednesday, September 30, 4:30 - 6:30 pm, Wangari Maathai
Rebecca Jackson1,2, Victoria Hodgson2, Matthew Lambon Ralph2, Elizabeth Jefferies1, Katya Krieger-Redwood1; 1University of York, 2University of Cambridge
The ability to selectively access and manipulate meaningful information based on context demands, relies upon a left-dominant ‘semantic control’ network (SCN) including inferior frontal and posterior temporal cortices. Surprisingly, this appears to differ anatomically from the multiple demand network (MDN) proposed to perform similar control operations across domains. However, prior comparisons are confounded by variations in task design. We performed two fMRI experiments to elucidate these differences and determine their driving factors. Firstly, we disentangled the effects of task process and stimulus domain during cognitively demanding tasks for the first time. Participants performed an odd-one-out task requiring inhibition and selection, and an n-back working memory task, each with meaningful semantic and non-semantic stimuli, in a factorial design. While task process was determined to be a confounding factor in prior studies, core SCN areas were preferentially engaged for semantic stimuli even when task processes and difficulty were matched. This differed from peripheral SCN and MDN regions. Secondly, we considered whether these effects are due to the impact of language by separating the effects of the meaningful nature of the stimuli from its verbal or pictorial format. Is the use of language, and the overlap with the putative Language Network, driving this difference? We again compared activation for the controlled selection of meaningful words and meaningless shapes, while adding meaningful pictures. While posterior temporal regions show relative variation by stimulus format, inferior frontal cortex activation is driven by meaning. The semantic control network is neither simply a domain-general control network, nor a language-general network, but is specialised for the control of meaningful verbal or nonverbal stimuli.
Topic Areas: Control, Selection, and Executive Processes, Meaning: Lexical Semantics