*2.3.5 Measurements of the stress state using alpha-amylase activity by sipping the subject's saliva*

In general, the stress state in human is evaluated using salivary alpha-amylase activity (sAA) to evaluate the change of the autonomic nervous function by sipping the subject's saliva [31–33]. We used a sheet of polyethylene terephthalate as a chip to collect the subject's saliva by putting it under the subject's tongue during about 30 s. After the collection of the subject's saliva, this chip was soon inserted in an enzyme analyzer (NIPRO Co. Ltd.: type T-110-N in Japan) to detect salivary alphaamylase activity (sAA) during about 60 s.

In these experiments, magnetoencephalography (MEG) was performed, and for the experiments of the stress state using the alpha-amylase activity by sipping, the subject's saliva was measured at the second times (the first measure, before experiments of MEG, and the second measure, after smelling "Zuko" incense rubbing into the hands and measuring the response of the brain using MEG experiments).

*Smelling "Zuko": Incense Rubbing into the Hands and Smelling the Hands Activates… DOI: http://dx.doi.org/10.5772/intechopen.88987*
