Brain oscillatory dynamics during discriminative vs CT-optimal touch

Area of Science:

• Neuroscience
• Somatosensation
• Psychophysics

Background:

• The affective dimension of touch is mediated by C-Tactile (CT) afferents.
• CT afferent stimulation modulates neural oscillations, but detailed brain dynamics remain underexplored.
• Understanding brain responses to affective touch is crucial for fields like neuroscience and psychology.

Purpose of the Study:

• To investigate brain oscillatory dynamics and spatial field distributions during CT afferent stimulation.
• To compare brain spectral power and microstates between affective (stroking) and discriminative (vibration) touch.
• To elucidate the neural basis of pleasant touch perception.

Main Methods:

• Electroencephalography (EEG) recording in 34 healthy participants.
• Tactile stimulation using a cosmetic brush (CT-optimal speeds) and vibrotactile stimuli (200 Hz).
• Analysis of power spectral density and EEG microstates.

Main Results:

• Stroking was rated as more pleasant than vibration, with similar intensity ratings.
• Reduced alpha/mu and beta band power in central/Rolandic areas during stroking compared to vibration.
• EEG microstate analysis revealed decreased prevalence of class A and increased prevalence of classes B and D during stroking.

Conclusions:

• CT-tuned stroking enhances sensorimotor cortical excitability.
• Affective touch engages greater attentional resources compared to discriminative touch.
• CT afferent stimulation represents a prioritized form of sensory information processing.