The Functional Network Processing Acute Electrical Itch Stimuli in Humans.

Area of Science:

• Neuroscience
• Neuroimaging
• Sensory processing

Background:

• The posterior insula (pIns) is crucial for relaying itch signals.
• Previous studies identified itch-responsive regions but not those processing pIns signals.
• Understanding pIns connectivity is vital for mapping itch processing networks.

Purpose of the Study:

• To identify brain regions with increased functional connectivity with the pIns during itch stimuli.
• To elucidate the key functional network involved in processing itch signals originating from the pIns.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used in 25 healthy subjects.
• Electrical itch stimuli were applied to the left wrist.
• Functional connectivity between the pIns and other brain regions was analyzed during itch perception.

Main Results:

• Significant functional connectivity increases were observed between the right pIns and the supplementary motor area (SMA), pre-SMA, anterior midcingulate cortex (aMCC), anterior insula (aIns), secondary somatosensory cortex (SII), and basal ganglia (BG).
• The intensity of functional connectivity between the pIns and basal ganglia (BG) was negatively correlated with subjective itch ratings.
• This suggests a key network for itch processing involving the identified regions.

Conclusions:

• The study identified a novel brain network for itch processing, centered on the posterior insula.
• The posterior insula-basal ganglia pathway appears critical for regulating the subjective experience of itch.
• This research provides foundational insights into the neural circuitry underlying itch sensation.