A developmental change of the visual behavior of the face recognition in the early infancy.

The purpose of this study was to examine developmental changes in visuocognitive function, particularly face recognition, in early infancy. In this study, we measured eye movement in healthy infants with a preference gaze problem, particularly eye movement between two face stimulations. We used the eye tracker system (Tobii1750, Tobii Technologies, Sweden) to measure eye movement in infants. Subjects were 17 3-month-old infants and 16 4-month-old infants. The subjects looked two types of face stimulation (upright face/scrambled face) at the same time and we measured their visual behavior (preference/looking/eye movement). Our results showed that 4-month-old infants looked at an upright face longer than 3-month infants, and exploratory behavior while comparing two face stimulations significantly increased. In this study, 4-month-old infants showed a preference towards an upright face. The numbers of eye movements between two face stimuli significantly increased in 4-month-old infants. These results suggest that eye movements may be an important index in face cognitive function during early infancy.

Hemodynamic changes in the breast and frontal cortex of mothers during breastfeeding.

The objective of this study was to confirm physiological reactions in the breast and brain in mothers during breastfeeding and collect basic objective data, aiming at effective support for breastfeeding. Ten healthy women who were exclusively breastfeeding their babies participated in this study. Changes in the concentration of oxygenated Hb (oxyHb) and deoxygenated Hb in the breasts and frontal cortex of these women during breastfeeding lactation were measured using double-channel near-infrared spectroscopy (NIRS). Changes were measured in three conditions: (1) in both breasts; (2) the ipsilateral breast and frontal cortex; and (3) the contralateral breast and frontal cortex. OxyHb and total Hb (totalHb) levels in the bilateral breasts decreased significantly after the onset of breastfeeding in comparison with prebreastfeeding levels. These two values repeatedly increased and decreased thereafter. In the frontal cortex, regardless of which breast was involved, oxyHb and totalHb levels increased significantly in comparison with prebreastfeeding levels. Similar hemodynamic changes occurred simultaneously in the bilateral breasts during breastfeeding regardless of the feeding or nonfeeding side. Hemodynamic changes were also noted in the frontal cortex, but the reactions in the breast and prefrontal cortex were different and not synchronous, confirming that the physiological circulatory dynamics during breastfeeding vary among organs.

Relationship between cerebral oxygenation and phosphorylation potential during secondary energy failure in hypoxic-ischemic newborn piglets.

The aim of this study was to evaluate the hypothesis that cerebral hemoglobin (Hb) oxygenation is related to phosphorylation potential during primary and secondary cerebral energy failure in newborn infants who have experienced birth asphyxia. We subjected newborn piglets to severe transient cerebral hypoxic-ischemia followed by resuscitation and examined cerebral energy metabolism by 31P-magnetic resonance spectroscopy and evaluated changes in cerebral Hb oxygen saturation (ScO2) using full-spectrum near-infrared spectroscopy before, during, and up to 54 h after the hypoxic-ischemic insult. ScO2 was significantly decreased during the hypoxic-ischemic insult compared with baseline values. During secondary energy failure, piglets were separated based on the relationship between the ratio of phosphocreatine to inorganic phosphate and ScO2; those with a negative correlation were less injured than those with a positive correlation. These results indicate that changes in ScO2 as measured by near-infrared spectroscopy are related to phosphorylation potential during secondary energy failure in asphyxiated infants.

Extrauterine environment affects the cortical responses to verbal stimulation in preterm infants.

Using optical topography, changes in the cerebral oxygenation were compared in the parieto-temporal lobe of preterm and term infants of equal postconceptional age in response to verbal stimulation. Eight preterm infants of gestational age 23-34 weeks were studied at postconceptional term age (38-46 weeks). Ten term infants were studied at 2-11 days after birth. Twenty-four-channel near-infrared optical topography (NIOT) was used to measure changes in concentration of oxyhemoglobin ([oxyHb]), deoxyhemoglobin ([deoxyHb]) and total hemoglobin ([totalHb]) in the bilateral temporal cortices. Verbal stimulation was provided by a recording of a Japanese fairy tale. The latency in response to verbal stimulation was significantly shorter in the preterm infants than in the term infants. This time is thought to reflect brain development, particularly the development of the neuro-vascular coupling mechanisms in the cerebral cortex. The present results indicate that the number of days after birth is more closely related to development of auditory system and neuro-vascular coupling than is postconceptional age. Thus, this suggests that early extrauterine environment affects the cortical responses to verbal stimulation in preterm infants.

Developmental changes of optical properties in neonates determined by near-infrared time-resolved spectroscopy.

Near-infrared spectroscopy has been used for measurement of changes in cerebral Hb concentrations in infants to study cerebral oxygenation and hemodynamics. In this study, measurements by time-resolved spectroscopy (TRS) were performed in 22 neonates to estimate the values of light absorption coefficient and reduced scattering coefficient (mu'(s)), cerebral Hb oxygen saturation (SCO2), cerebral blood volume (CBV), and differential pathlength factor (DPF), and the relationships between postconceptional age and mu'(s), SCO2, CBV, and DPF were investigated. A portable three-wavelength TRS system with a probe attached to the head of the neonate was used. The mean mu'(s) values at 761, 795, and 835 nm in neonates were estimated to be (mean +/- SD) 6.46 +/- 1.21, 5.90 +/- 1.15 and 6.40 +/- 1.16/cm, respectively. There was a significant positive relationship between postconceptional age and mu'(s) at those three wavelengths. The mean SCO2 value was calculated to be 70.0 +/- 4.6%, and postconceptional age and SCO2 showed a negative linear relationship. The mean value of CBV was 2.31 +/- 0.56 mL/100 g. There was a significant positive relationship between postconceptional age and CBV. The mean DPF values at 761, 795, and 835 nm were estimated to be 4.58 +/- 0.41, 4.64 +/- 0.46, and 4.31 +/- 0.42, respectively. There was no relationship between postconceptional age and DPF at those three wavelengths. The results demonstrated that our near-infrared TRS method can be used to monitor mu'(s), SCO2, CBV, and DPF in the neonatal brain at the bedside in an intensive care unit.

Quantification of cerebral hemoglobin as a function of oxygenation using near-infrared time-resolved spectroscopy in a piglet model of hypoxia.

Near-infrared spectroscopy (NIRS) has been used for measurement of cerebral hemoglobin (Hb) concentrations in neonates to study cerebral oxygenation and hemodynamics. We perform measurements by portable three-wavelength NIR time-resolved spectroscopy (TRS) in a piglet hypoxia model with various degrees of oxygenation to estimate the absorption coefficient (mu(a)) and reduced scattering coefficient (mu(s)') of the head. Measurements of absolute values of mu(a) at three wavelengths enable estimation of Hb concentration and Hb oxygen saturation in the head (SO2). However, there is a problem concerning which background absorption should be used to estimate Hb concentration in the head derived from mu(a) at three wavelengths because it is different from a simple in vitro model. Therefore, we use two different background absorption values with the assumption that background absorption is due only to 85% (by volume) water or that background absorption is equal to absorption of the piglet head with blood exchange transfusion by fluorocarbon (FC), and we compared SO2 measured by TRS with arterial Hb oxygen saturation (SaO2) and sagittal sinus venous Hb oxygen saturation (SvO2) measured by a co-oximeter at several inspired fractional O2(FI(O2)) concentrations. We find that SO2 values using the absorption (abs) of the piglet head with blood exchange transfusion (BET) by FC are not significantly different from SO2 values using the water-only background at FI(O2) in the range of 15 to 100%, but that the values using abs of the head with BET by FC are lower than the values using the water-only background at FI(O2) in the range of 12 to 4%. The SO2 values calculated from the water-only background are higher than those of SaO2 at FI(O2) in the range of 10 to 4%. However, SO2 values using the abs of the head with BET by FC are between those of SaO2 and SvO2 over the whole range of FI(O2). Therefore, abs of the head with BET by FC is more useful for estimation of the absolute values of oxyHb and deoxyHb of the piglet head.

Changes in cerebral glucose metabolism in newborn infants with cerebral infarction.

Cerebral infarction in infants is not uncommon, and it differs in many important ways from cerebral infarction in older children and adults. Computed tomography, ultrasound, and conventional and diffusion-weighted magnetic resonance imaging are useful for diagnosing cerebral infarction, but these imaging techniques cannot be used to measure cerebral blood flow and metabolic activity. Abnormality in those parameters seems to follow a different pattern and time course than those in older patients. In this study, the rapid changes in regional cerebral blood flow and metabolic rate of glucose were estimated by single-photon emission computed tomography and positron emission tomography during the acute and subacute phases of neonatal infarction. Subacute increases in blood flow and metabolic rate in the infarcted area of a term infant with multiple apneic episodes within 2 days after birth were observed, as well as acute increases in both in the infarcted area of a term infant with acute clonic seizures within 24 hours after birth. Follow-up studies at 4 months for the first infant and at 10 days for the second infant demonstrated that both the blood flow and metabolic rate in the infarcted region decreased. The results of this study should contribute to an understanding of the relationship between blood flow and metabolic rate changes after neonatal infarction as well as to improvement of diagnosis of neurologic impairments in neonates.