ObjectiveTo investigate the immediate brain effect of auricular electroacupuncture(EA) in the treatment of primary insomnia(PI).MethodsIn this study

15 subjects with PI who were diagnosed according to Pitsburgh Sleep Quality Index(PSQI)

and other 15 age-and gender-matched subjects without insomnia were recruited in the present study. The PI patients received EA(4 Hz/20 Hz

a tolerable electrical current strength)of auricular concha for 30 min

and their resting state functional magnetic resonance imaging(fMRI)data before and after treatment were collected. The healthy subjects received no any treatment and their resting state fMRI data were collected. The difference of default mode network functional connectivity between the patients and healthy subjects

and changes of the patient's brain functional connectivity after EA treatment were estimated by using seed-point-based analysis(SPBA).ResultsAnalysis by taking the posterior cingulate gyrus as the seed-point showed that compared with the healthy participants before treatment

the patient's brain functional connectivity between the posterior cingulate gyrus and the right insula

or the inferior frontal gyrus of the right opercularis region

or the right rolandic operculum was increased. After 30 minutes' EA treatment

the functional connectivity between the posterior cingulate gyrus and the precuneus

the left angular gyrus

the left frontal superior gyrus

the left frontal middle cortex

the right temporalis inferior gyrus

the right temporalis middle gyrus or the left medial orbitofrontal cortex was decreased

while the functional connectivity between the posterior cingulate gyrus and the right lingual gyrus

or the cortex surrounding the right calcarine fissure was increased.ConclusionEA of auricular concha has an instant effect in modulating the brain default mode network in PI patients

which may be its brain mechanism underlying improvement of PI.