Pupil-Linked Arousal Modulates Precision of Stimulus Representation in Cortex

Area of Science:

• Neuroscience
• Cognitive Science
• Psychology

Background:

• Neural responses exhibit inherent trial-to-trial variability, even with stable stimuli.
• The underlying causes of this neural variability, particularly in cortical representations, remain incompletely understood.
• Arousal state fluctuations are a potential, yet underexplored, factor influencing neural signal fidelity.

Purpose of the Study:

• To investigate whether spontaneous changes in arousal state contribute to variability in neural population activity.
• To determine if arousal state modulates the precision of stimulus representations in the human visual cortex.
• To examine the behavioral consequences of arousal-modulated neural precision.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) and probabilistic decoding to assess visual cortex stimulus representation precision.
• Employed pupillometry to continuously monitor and quantify participants' arousal state.
• Combined neuroimaging and pupillometry with behavioral tasks (orientation judgment and confidence ratings) to link neural, physiological, and behavioral measures.

Main Results:

• Found significant trial-to-trial variability in the precision of visual cortical stimulus representations, subjective confidence, and behavioral judgments.
• Demonstrated a strong correlation between pupil size (pre-stimulus dilation and during stimulus presentation) and the precision of neural representations.
• Showed that increased pupil dilation during stimulus presentation was associated with higher confidence and improved behavioral performance.

Conclusions:

• Spontaneous fluctuations in arousal state significantly modulate the fidelity of stimulus representations in the human visual cortex.
• These arousal-driven changes in neural representation precision have direct and measurable consequences on sensory perception and behavior.
• Pupillometry serves as a valuable, non-invasive index for tracking arousal-related modulations of neural processing and perception.