**1. Introduction**

In general, incense can be classified mainly into two groups, one of which is a kind of smelling the odor of stick by burning it and another is smelling the odor of "Zuko" rubbing into the hands. There are two major types of incense in Japan, one of which is direct burning incense of sticks and another is not burning and called "Zuko," smelling incense rubbed into the hands by using small pieces of powders [1, 2].

In Japanese smelling "Zuko" rubbed into the hands has been recently often applied to the usage as a kind of smelling incense in daily life. The special meaning of "Zuko" is known as directly smelling the hands with rubbed incense and cleaning the self by the hands with cleaning his/her emotion at the same time.

In these experiments, we are trying to study how "Zuko" has the effects to the human brain.

It is known that olfactory neuronal processing was found in the orbitofrontal cortex (OFC) in the human brain from the previous studies [3–5]. In the recent

researches, sniffing and smelling were important function of the "active olfaction" [6, 7]. On the other hand, imitation of smelling hands and the behavior of putting the hands together were investigated as an activation of mirror neurons and an operation of the default-mode network [8–12].

1.Agarwood (*Aquilaria agallocha*, *Aquilaria agallocha* Roxburgh)

*Smelling "Zuko": Incense Rubbing into the Hands and Smelling the Hands Activates…*

3.Benzoin (*Styrax tonkinensis*, *Styrax tonkinensis* Craib et Hortwick)

**2.3 Methods of MEG experiments and algorithms of source estimation**

In this study, we applied to the signal source an estimation by using "spatiotemporal dipole fit" theory [16]. We obtained the value of an estimated current dipole continuously using a unit time step by step at every 50 ms, in turn. From these timevarying analyses, the most suitable dipole was obtained at the most reliable time for MEG data in the experiment. This "time-varying analysis" is the method using time-varying covariate (also called time-dependent covariate) in statistics, particularly in survival analyses. It reflects the phenomenon that a covariate is not necessarily constant through the whole study to get the suitable higher goodness of fit

In this study, we were selecting the most suitable dipole from these dipoles estimated in time varying at every 50 ms. In these single dipoles for this timevarying estimation method, the most reliable ECD was of course obtained as a very higher goodness of fit (GOF) more than 80% by using the above time-varying analysis. These ECDs were fitted using iterative algorithms which estimated the source parameters in order to explain the MEG data as accurate as possible [25, 26]. A smoothing spline is also used to propose a novel model for the time-varying quantile of the univariate time series using a state-space approach. A correlation is further incorporated between the dependent variable and its one-step-ahead quantile. Using a Bayesian approach, an efficient Markov chain Monte Carlo algorithm is described where we use the multi-move sampler, which generates simulta-

In our source reconstruction analysis, three main components were characterized. The first was related to the definition of the solution space, and the second was reconstructed by the information of the physical and geometrical characteristics of the head. The third was treated by modeling the propagation of the source electromagnetic fields through various tissues in the brain [28, 29]. In these inverse

*2.3.1 Signal source estimation using the theory of "spatiotemporal dipole fit"*

From the previous 11 Japanese volunteer subjects, in this analysis 10 subjects (5 males, 5 females) between the ages of 22 and 58 years (mean age 41 11 years) were chosen. These subjects were tested by using the previous two types of incense sticks for the effects of the simultaneous smelling incense odor and putting the hands together. However, for only one subject N1 in the previous 11 subjects, it was tested how his brain showed the response to smelling a "Zuko" incense into the hands and putting the hands together by using the analyses of MEG and MRI experiment [23]. On the other hand, in this experiment new other 10 subjects (5 males, 5 females) between the ages of 31 and 73 years (mean age 54.1 7.8 years) who were selected with higher ages than the above subjects participated. They were tested by using "Zuko," an incense which were rubbed into their hands for the effects of simultaneous smelling." All subjects had no significant smell loss, and they were given the informed consent perfectly by the ethical committee on human studies under Helsinki treaty

2. Sandalwood (*Santalum album*, *Santalum album* L)

*DOI: http://dx.doi.org/10.5772/intechopen.88987*

in both AIST and Aino University in Japan.

(GOF) for the estimation [24].

neously latent time-varying quantiles [27].

**175**

**2.2 Subjects**

In the analysis of brain activity, fMRI, PET, EEG, and MEG are usually applied. In general fMRI and PET are suitable to measure the metabolism of physiological activities but not suitable to measure the real-time changes of neuronal activities. On the other hand, it is known that the advantage of MEG is suitable to obtain the real-time changes of the presiding neural activities in the brain by millisecond time resolution [13, 14]. MEG method is more excellent than EEG method because no distortion of an electro-resistance in the brain was found. So, we applied MEG experiments to this study for the estimation of signal source in the brain.

In our MEG experiments, we used to trace the cortical current by the first-order differential planar type of DC-SQUID sensors. This MEG sensor system has the greatest advantage of using the differential planar type of device.

The determination of a current source is very precise and useful because the current source exists in the maximum of absolute magnetic field values [15]. This estimated main current source was the largest dipole, and the second and the third current dipoles were smaller and weaker than the first main dipole.

To improve up fittingness of the estimation, we applied "spatiotemporal dipole fit theory" introduced by Scherag et al. [16] in which the time-varying amplitude of each dipole was applied at every 50 ms intervals. For the estimation of the signal source, we applied time-varying analysis method to obtain the most suitable MEG dipole which is called equivalent current dipole. From this time-varying analysis, we obtained the most suitable single dipole at every 50 ms in real-time analysis continuously.

The event-related responses (ERPs) in the human brain were studied as an inner mental state or the various psychological factors having an inner origin in the brain, for example, using measuring brain waves and so on. A P300 response peak in brain waves was researched as a response of "cognitive function" by using "oddball paradigm" experiment [17–19]. This P300m response (the magnetic P300 response peak is called as P300m in the MEG experiment) was investigated for the olfactory cognitive function, too. From these reasons, we can study P300m response to test the cognitive ability of olfaction [20].

The alpha-amylase value in the saliva is known as a kind of marker and an index of stress states in human [21, 22]. So we can have alpha-amylase in the saliva to test the stress state for the response of olfactory function in human before or after smelling "Zuko" incense.

The purpose of this study is to clarify that smelling "Zuko" incense rubbing into the hands and putting the hands together more activate the human brain than smelling incense odors using sticks burned such as the responses obtained from our previous study and to show how specific areas in the brain are activated.
