The Neural Processes Underpinning Flexible Semantic Retrieval in Visual and Auditory Modalities.

Area of Science:

• Neuroscience
• Cognitive Science
• Psychology

Background:

• Semantic cognition relies on conceptual stores and retrieval processes.
• Neural basis of semantic control across different sensory modalities is not well understood.
• Control networks may be organized along a unimodal-to-heteromodal cortical gradient.

Purpose of the Study:

• To investigate how the semantic control network (SCN) and multiple demand network (MDN) respond to semantic control demands in visual and auditory tasks.
• To examine the neural basis of semantic control across modalities.
• To determine if SCN and MDN activity is modulated by task structure and perceptual difficulty.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to study brain activity.
• Participants performed semantic relatedness judgments on spoken and written word pairs.
• Task cues were manipulated to guide semantic feature retrieval.

Main Results:

• The SCN showed increased activation when task knowledge was available, suggesting a role in top-down semantic retrieval across modalities.
• The MDN exhibited greater activation for spoken words, likely due to increased speech perception demands.
• A dissociation was observed between the SCN and MDN based on task structure and perceptual difficulty.

Conclusions:

• The SCN is involved in top-down control of semantic retrieval, modulated by task structure.
• The MDN's activity is influenced by perceptual difficulty, particularly in auditory tasks.
• Findings demonstrate distinct roles for SCN and MDN in semantic control across sensory modalities.