Task complexity relates to activation of cortical motor areas during uni-and bimanual performance: a functional NIRS study Holper, L; Biallas, M; Wolf, M Holper, L; Biallas, M; Wolf, M (2009 AbstractHand motor tasks are frequently used to assess impaired motor function in neurology and neurorehabilitation. Assessments can be varied by means of hand laterality, i.e. unimanual or bimanual performance, as well as by means of task complexity, i.e. different degrees ranging from simple to complex sequence tasks. The resulting functional activation in human primary motor cortex (M1) has been studied intensively by traditional neuroimaging methods.Previous studies using functional near-infrared spectroscopy (fNIRS) investigated simple hand motor tasks. However, it is unknown whether fNIRS can also detect changes in response to increasing task complexity. Our hypothesis was to show that fNIRS could detect activation changes in relation to task complexity in uni-and bimanual tasks.Sixteen healthy right-handed subjects performed five finger-tapping tasks: unimanual left and right, simple and complex tasks as well as bimanual complex tasks. We found significant We report for the first time that fNIRS detects oxygenation changes in relation to task complexity during finger-tapping. The study aims to contribute to the establishment of fNIRS as a neuroimaging method to assess hand motor function in clinical settings where traditional neuroimaging methods cannot be applied.

The results of this study suggest that acute cerebral hemodynamic consequences of SDB lead to a failure of autoregulatory mechanisms with brain hypoxia only in the presence of frequent apneas (AHI > 30) and obstructive events.

Precision of cerebral oxygenation and hemoglobin concentration measurements in neonates measured by near-infrared spectroscopy Abstract. Background and aim: One source of error with near-infrared spectroscopy (NIRS) is the assumption that the measured tissue is optically homogeneous. This is not always the case. Our aim is to assess the impact of tissue homogeneity (TH) on the precision of NIRS measurements in neonates. Methods: On 36 term and 27 preterm neonates at least five 1-min measurements are performed on each subject using the OxiplexTS. The sensor position is slightly changed before each measurement while assessing TH. The precision for cerebral tissue oxygenation saturation (StO 2 ) and total hemoglobin concentration (tHb) are calculated by repeated measures analysis of variance. Results: The mean StO 2 is not significantly different between term and preterm infants. The mean tHb is significantly lower in preterm infants (p < 0.01). With increasing TH, the precision of StO 2 increase from 5.6 to 4.6% for preterm and from 11.0 to 2.0% for term infants; the precision of tHb increases from 10.1 to 7.5μM for preterm and from 16.4 to 3.5μM for term infants. The precision for StO 2 is higher in term than in preterm infants. The precision for tHb shows no significant difference between the two groups. Conclusions: The precision of NIRS measurements correlates with tissue homogeneity. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Early detection of cerebral hypoxemia is an important aim in neonatology. A relevant parameter to assess brain oxygenation may be the cerebral tissue oxygen saturation (StO(2)) measured by near-infrared spectroscopy (NIRS). So far the reproducibility of StO(2) measurements was too low for clinical application, probably due to inhomogeneities. The aim of this study was to test a novel sensor geometry which reduces the influence of inhomogeneities. Thirty clinically stable newborn infants, with a gestational age of median 33.9 (range 26.9 to 41.9) weeks, birth weight of 2220 (820 to 4230) g, postnatal age of 5 (1 to 71) days were studied. At least four StO(2) measurements of 1 min duration were carried out using NIRS on the lateral head. The sensor was repositioned between measurements. Reproducibility was calculated by a linear mixed effects model. The mean StO(2) was 79.99 ± 4.47% with a reproducibility of 2.76% and a between-infant variability of 4.20%. Thus, the error of measurement only accounts for 30.1% of the variability. The novel sensor geometry leads to considerably more precise measurements compared to previous studies with, e.g., 5% reproducibility for the NIRO 300. The novel StO (2) Abstract. Early detection of cerebral hypoxemia is an important aim in neonatology. A relevant parameter to assess brain oxygenation may be the cerebral tissue oxygen saturation (StO 2 ) measured by near-infrared spectroscopy (NIRS). So far the reproducibility of StO 2 measurements was too low for clinical application, probably due to inhomogeneities. The aim of this study was to test a novel sensor geometry which reduces the influence of inhomogeneities. Thirty clinically stable newborn infants, with a gestational age of median 33.9 (range 26.9 to 41.9) weeks, birth weight of 2220 (820 to 4230) g, postnatal age of 5 (1 to 71) days were studied. At least four StO 2 measurements of 1 min duration were carried out using NIRS on the lateral head. The sensor was repositioned between measurements. Reproducibility was calculated by a linear mixed effects model. The mean StO 2 was 79.99 ± 4.47% with a reproducibility of 2.76% and a between-infant variability of 4.20%. Thus, the error of measurement only accounts for 30.1% of the variability. The novel sensor geometry leads to considerably more precise measurements compared to previous studies with, e.g., ∼5% reproducibility for the NIRO 300.