**4. Discussion**

108 Infrared Spectroscopy – Life and Biomedical Sciences

Left hemisphere Right hemispher

Anterior

Channels were grouped into 5 regions and effect sizes from each region were averaged.

Posterior

Yellow framework: premotor area, Pink framework: sensorimotor area, Green

Right auricle

framework: parietal lobe

Situation 1: No object is presented, Situation 2: An object is presented.

object presentation reduces the degree of illusory hand joint flexion.

Fig. 7. Differences in angles of hand joint flexion between Situations 1 and 2

There is a significant reduction of flexion angles in situation 2 compared to situation 1. In other words,

Situation 1 Situation 2

Fig. 6. Schema of regions of interest analysis

\* P<0.05

Left auricle

> The present results clarified that the angle of illusion was decreased by placing a visible object within the range of illusory movement of the subject's own hand. It is therefore evident that visual sensation can modify illusory movement, indicating that the environment largely influences movement cognition. The effect size of the channels corresponding to the right premotor area were significantly reduced when vibratory stimulation was given in the presence of a visible object in comparison with absence of an object. In summary, the reduction in activity of the right premotor area was assumed to have diminished illusory movement as suggested by a positive correlation between intensities of the area activity and those of the illusion. That this correlation was not significant may have been because of the small subject population. It was thus clear that the activity of the premotor area of the right hemisphere influenced perception of movement and that the degree of activation of the right premotor area was involved in formation or suppression of movement perception.

> The right premotor area is the region responsible for bodily self-attribution as evidenced by Ehrsson et al.10) Evidence of the predominance of the right hemisphere in illusory perception of limb movement elicited by tendon vibration was also reported.8) Our present study added new information that a decline in activity in the premotor area suppressed illusory movements. Pinocchio's illusion11) helps explain this observation. When an illusory movement of elbow extension is provoked by vibratory stimulation with your nose being pinched, you feel as if your nose got longer. This phenomenon occurs to clear up a contradiction between illusory limb movements and constant input of tactile sensation from the nose. In this study, the subject should have touched an object due to illusory movements if it had existed within the illusory angle of the subject's own hand. Our results suggested that the degree of illusory movements was lowered due to lack of tactile sensation and that the right premotor area might be involved in variability of illusory movements.

> From these results it was clarified that movement perception based on activity of muscle spindles was easily modified by a change in visual information even though the intensity of

**8** 

**Probing Brain Oxygenation Waveforms with Near Infrared Spectroscopy (NIRS)** 

Alexander Gersten1, Jacqueline Perle2,

*2Department of Psychology,* 

*McGill University, Montreal 5City University of New York, NY* 

> *1,3Israel 2,5USA 4Canada*

Dov Heimer3, Amir Raz4 and Robert Fried5

*1Department of Physics, Ben-Gurion University, Beer-Sheva* 

*4McConnell Brain Imaging Centre, Montreal Neurological Institute,* 

Breathing may have dramatic effects on the human cerebral blood flow (CBF) and cognition. This was already known long time ago to Chinese (Li Xiuling, 2003), Hindus (Kuvalayananda, 1983) and Tibetans (Mullin, 1996). The main parameter influencing the CBF is the arterial partial pressure of carbon dioxide (PaCO2). About 70% increase in PaCO2 may double the blood flow (Sokoloff, 1989, Guyton, 1991). The increase of blood flow to the brain results in an increase of nutrients and oxygen, which may influence to great extent

On the other hand lowering the PaCO2 through hyperventilation found an application in

An evaluation of the CBF dependence on PaCO2 was given by Gersten (Gersten, 2011). The human normal value of PaCO2 is about 40 mmHg. Fig. 1 depicts our estimation of the changes of CBF as a result of changing PaCO2 from normal. The estimate is based on the data of Refs. (Reivich 1964, Ketty and Schmidt 1948, Raichle et all 1970). An increase of only 12.5% from normal in PaCO2 leads to the state of hypercapnia (PaCO2 above 45 mm Hg).

With aging both CBF and PaCO2 tends to fall down, therefore breathing exercises (or procedures) with the aim to increase PaCO2 and CBF might be important in preventing and alleviating neurodegenerative diseases. They may be also important in improving intellectual abilities. The amount of PaCO2 in our arteries is proportional to the CO2 which was metabolized by the organism and inversely proportional to the lung ventilation (i.e. to the amount of air exchanged between the lungs and the environment in one minute).

**1. Introduction** 

brain's physiology.

neurosurgery (Feihl and Perret, 1994).

*Hunter College of the City University of New York, NY 3Pulmonary Unit, Soroka University Hospital, Beer-Sheva* 

vibratory stimulus was fixed. Namely, bottom-up processing of sensory information from afferent fibers is influenced by its top-down processing. On the other hand, it remains unclear what directly reduced the activity of the right premotor area. To answer this question, it is necessary to examine if an object presented outside the angle of illusion changes the degree of illusory movements. In addition, it will be necessary to study the status of activities of visual cortical areas as well as of prefrontal areas rather than study premotor areas.

#### **5. References**

