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Task Relevance Modulates Somatosensory Awareness Depending on Stimulus Intensity
Alice Giorgi1,2, Erica Bonomi1, Enrico Salemi1,2
1Neuroscience Institute, National Research Council of Italy, Rome, Italy.
The European Journal of Neuroscience
|September 26, 2025
Summary
The P3b brain response is linked to task relevance, not awareness. Somatosensory awareness negativity (SAN) reflects awareness, but only for difficult-to-detect stimuli when task demands are present.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychology
Background:
- Somatosensory evoked potentials (SEPs) include P3b and somatosensory awareness negativity (SAN).
- P3b is thought to reflect postperceptual processes like reporting, while SAN is linked to awareness.
- Previous studies lacked conditions to clearly separate awareness from task-related processes.
Purpose of the Study:
- To verify if P3b is dependent on reporting and absent in no-report conditions.
- To determine how task relevance and stimulus amplitude modulate SAN.
- To distinguish neural correlates of awareness from task-related processing.
Main Methods:
- Experimental procedure varying stimulus amplitude (sensory/motor threshold) and task relevance (no-report, report+relevant, report+irrelevant).
- Measurement of somatosensory evoked potentials (SEPs).
- Analysis of P3b and SAN components in relation to experimental conditions.
Main Results:
- P3b was present only when stimulus reporting was required and absent in the no-report condition.
- SAN was modulated by task relevance, but only for stimuli near the detection threshold.
- Task relevance enhances neural responses for stimuli challenging to detect, influencing conscious perception.
Conclusions:
- P3b is associated with task relevance and stimulus reporting, not sensory awareness.
- SAN serves as a proxy for awareness in attentional manipulations, particularly for near-threshold stimuli.
- Task relevance influences conscious perception by enhancing neural responses to difficult stimuli.
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