**Near-Infrared Spectroscopic Assessment of Haemodynamic Activation in the Cerebral Cortex – A Review in Developmental Psychology and Child Psychiatry**

Hitoshi Kaneko1, Toru Yoshikawa2, Hiroyuki Ito3, Kenji Nomura1, Takashi Okada2 and Shuji Honjo1 *1Center for Developmental Clinical Psychology and Psychiatry, Nagoya University 2Department of Psychiatry for Parents and Children, Nagoya University Hospital 3Osaka-Hamamatsu Joint Center for Child Development, Hamamatsu University School of Medicine Japan* 

#### **1. Introduction**

150 Infrared Spectroscopy – Life and Biomedical Sciences

Wagner, J., Stephan, T., Kalla, R., Brückmann, H., Strupp, M., Brandt, T., & Jahn K. (2008).

pp.247-255, ISSN 1432-1106.

Mind the Bend: Cerebral Activations Associated with Mental Imagery of Walking along a Curved Path, *Experimental Brain Research*, Vol.191, No.2, (November 2008),

> This chapter aims to shed light on developmental cognitive neuroscience studies that use near-infrared spectroscopy (NIRS) to examine the cortical response in developmental psychology and child psychiatry. NIRS was first applied to the human brain in 1977 (Jöbsis, 1977) for the noninvasive measurement of the haemodynamic activation in the cerebral cortex. NIRS is advantageous over other neuroimaging methods in terms of its ease of measurement and low cost. Therefore, extensive studies have investigated neural correlates using the NIRS technique in healthy people and in neurological or psychiatric patients. Furthermore, NIRS has been applied to multiple age groups from neonates to adults. It is beyond the scope of this chapter to provide an exhaustive list of the neuroscience research based on NIRS. Here, we focus mainly on the studies that examine cognitive function from the viewpoint of developmental cognitive neuroscience.

> We believe that studies on brain function in children from birth to adolescence who are healthy or have psychiatric disorders provides knowledge about the trajectory of cognitive and neural development. The advantages of NIRS over magnetoencephalography (MEG) or functional magnetic imaging (fMRI) include easy measurement and less susceptibility to signal distortion by motion artefacts (Gervain et al., 2011; Lloyd-Fox et al., 2010). Furthermore, NIRS enables the measurement of human cerebral activity in less restricted and less noisy conditions. This advantage is particularly important in studies that investigate children from infancy to adolescence. NIRS enables researchers to easily present auditory stimuli (Kaneko et al., 2011) and to conduct experiments in relatively natural social settings (Ito et al., 2011). NIRS can be performed on infants even while they sit upright on

Near-Infrared Spectroscopic Assessment of Haemodynamic Activation in

changes can be used to determine the haemodynamic response.

**4. Applications in developmental psychology** 

cerebral oxygenation saturation in the NICU (Brazy et al., 1985).

**4.1 Functional brain activity in infants** 

probes and headgear designed for infants.

**cortex** 

Strangman et al., 2002).

2007b, 2009).

the Cerebral Cortex – A Review in Developmental Psychology and Child Psychiatry 153

Biological tissue is relatively transparent to light in the near-infrared range. In NIRS, light at wavelengths of 700–900 nm is illuminated onto the scalp. Oxy-haemoglobin and deoxyhaemoglobin chromophores have different absorption spectra that are used to assess the attenuated light levels via changes in the chromophore concentration; these concentration

Because oxygen consumption increases in the region of the brain with the greatest activity, changes in the oxygen content of the blood can be used to measure the relative levels of brain activity. The specific parameters of the response monitored with NIRS represent changes in the levels of oxygenated and deoxygenated haemoglobin at specific regions across the cerebral cortex during stimulation. The detailed principles of NIRS have been described previously (e.g. Gervain et al., 2011; Hoshi, 2007; Minagawa-Kawai et al., 2008;

After Jöbsis first applied NIRS to the human brain (Jöbsis, 1977), there has been an increasing interest in measuring the haemodynamic response in the cerebral cortex of humans, especially in neonatal patients in the neonatal intensive care unit (NICU). NIRS is especially suitable for studies in neonates and is increasingly used in high-risk neonates, including low-birth-weight infants, neonates with congenital heart defects, and neonates with other pathological states (Goff et al., 2010; Wyatt et al., 1986). The neonatal skull is thinner than that of adults; therefore, near-infrared light can penetrate deeper into the neonatal cortex than into the adult cortex. The first study to use NIRS to evaluate cerebral oxygenation saturation in pre-term infants was published in 1985 (Brazy et al., 1985). Subsequently, extensive research has revealed that NIRS is highly effective for monitoring

Although numerous studies have demonstrated that NIRS is valuable for the assessment of neonates in the NICU, the use of NIRS in measuring cognitive function in infants has not been fully investigated. Early NIRS studies examined infants who were presented with stimuli while they were asleep (Aoyama et al., 2010; Homae et al., 2007; Saito et al., 2007a,

Over the last decade, NIRS has been successfully applied to awake infants in experimental settings (Homae et al., 2010; Hyde et al., 2010; Nakano et al., 2009; Taga et al., 2003; Taga & Asakawa, 2007; Watanabe et al., 2010; Wilcox et al., 2008, 2009, 2010). Figure 1 shows an experimental setting where infants can sit upright on the lap of a parent wearing NIRS

In the next section, we address the neural activation during face recognition in infants. Face recognition is important for infants and adults, because the face represents not only the personal identity but also the emotional expressions of an individual. In social communication, it is essential to understand the thoughts of a person via their facial expressions. Although many event rerated potential (ERP) studies in infants have examined

**3. NIRS: Principles and methods in the assessment of the human cerebral** 

the lap of a parent. Therefore, NIRS is especially suited for research on children from birth to the toddler years (Lloyd-Fox et al., 2010).
