Task instructions modulate the attentional mode affecting the auditory MMN and the semantic N400

Area of Science:

• Neuroscience
• Cognitive Psychology
• Clinical Electrophysiology

Background:

• Event-related potentials (ERPs) are crucial for assessing cognitive function in disorders of consciousness.
• Current ERP research often uses passive listening, contrasting with active instructions used in healthy participant studies.
• The impact of attentional instructions on ERP components like N400 and MMN remains incompletely understood.

Purpose of the Study:

• To investigate the influence of attentional modulation, specifically active versus passive instructions, on ERP components.
• To examine the effects of different auditory task instructions (ignore, passive, focused attention) on N400 and MMN.
• To assess subjective effort associated with varying levels of auditory attention during EEG recording.

Main Methods:

• 18 healthy participants completed three auditory paradigms (oddball, word priming, sentence).
• Each paradigm was presented under three instruction conditions: ignore, passive listening, and focused attention.
• Subjective effort ratings were collected after each task condition.

Main Results:

• N400 amplitude decreased from focused to passive tasks and was absent in the ignore task.
• Mismatch negativity (MMN) amplitudes were higher in focused and passive tasks compared to the ignore task.
• Subjective effort was high in passive and focused tasks, but reduced when ignoring stimuli.

Conclusions:

• Attentional state significantly affects ERP components, including the N400 and MMN.
• Passive listening during EEG recording is not neutral and can induce stress, potentially altering ERPs.
• The findings complicate the interpretation of ERP data collected under passive conditions, particularly in clinical populations.