Do Not Forget the Stimulus: A Missing Control in Naturalistic Studies of Neural Entrainment

Area of Science:

• Cognitive Neuroscience
• Auditory Neuroscience
• Speech Processing

Background:

• A key debate in cognitive neuroscience concerns whether brain rhythms during speech perception arise from intrinsic neural oscillations or are evoked by the acoustic signal.
• Previous intracranial studies suggested neural entrainment to speech, interpreting persistent auditory activity after acoustic edges as evidence.

Purpose of the Study:

• To investigate whether rhythmic patterns observed in brain activity during speech perception are generated by the brain's intrinsic oscillations or are present in the speech stimulus itself.
• To challenge the interpretation of persistent auditory activity as solely evidence for neural entrainment.

Main Methods:

• Analysis of rhythmic patterns within the speech stimulus.
• Comparison of stimulus-based rhythms with neural activity patterns.
• Utilizing intracranial recordings from a previous study.

Main Results:

• A rhythmic pattern, similar to that observed in neural activity, was found to be inherent in the speech stimulus.
• This finding supports an evoked-response account over an intrinsic neural oscillation or entrainment explanation.
• The study demonstrates that previously interpreted neural entrainment may be an artifact of stimulus-driven responses.

Conclusions:

• The observed rhythmic activity in speech perception likely reflects evoked responses to the acoustic signal rather than solely intrinsic neural oscillations.
• Routine stimulus-signal analyses are crucial for accurately interpreting neural responses during naturalistic speech processing.
• This work necessitates a re-evaluation of evidence for neural entrainment in auditory perception studies.