This randomized, crossover sham controlled trial with sham intended to study the effect of electrical stimulation on peripheral nerve (spinal accessory nerve) with acupuncture needle in healthy subjects aims to access the effect o electrical stimulation of accessory spinal nerve in cortical activation, muscular perfusion and autonomic response in healthy subjects.

Participants will be assessed through measure changes in cortical activation, local muscular peripheral perfusion and autonomic responses before and after intervention and intervention-sham, and crossed after a period of wash-out.

The design aims to contribute to assessment of one electroacupuncture's techniques by measuring some of the physiological effects caused by peripheral stimulation.

In recent years, there are growing evidence that many diseases such as chronic pain and psychiatric disorders can be managed with non-pharmacological techniques. The possibility of inducing central neuroplastic responses through transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) has been widely studied, as well as peripheral stimulation techniques such electroacupuncture (EA) and intramuscular stimulation (IMS). However, there are few studies on physiological mechanisms, indications and limitations of each technique.

Thus, this randomized, crossover sham controlled trial, where sham intended to study the effect of electrical stimulation on peripheral nerve (spinal accessory nerve) with acupuncture needle in healthy subjects aims to access the effect o electrical stimulation of accessory spinal nerve in cortical activation, muscular perfusion and autonomic response in healthy subjects.

Participants will be assessed through measure changes in cortical activation, local muscular peripheral perfusion and autonomic responses before and after intervention and intervention-sham, and crossed after a period of wash-out.

The design aims to contribute to assessment of one electroacupuncture's techniques by measuring some of the physiological effects caused by peripheral stimulation.

Inclusion Criteria:

• healthy male subjects
• right handed
• basic education

Exclusion Criteria:

• contraindication to infrared technology NIRS
• brain stimulator device
• drug and alcohol abuse
• chronic disease (any);
• chronic pain condition
• tobacco use
• psychiatric disorders
• Beck Depression Inventory higher then score 12
• psychotropic drugs
• use of pain-killers or anti-inflammatories 12h previous experiment