In the absence of any overt task performance, it has been shown that spontaneous, intrinsic brain activity is expressed as systemwide, resting-state networks in the adult brain. However, the route to adult patterns of resting-state activity through neuronal development in the human brain is currently unknown. Therefore, we used functional MRI to map patterns of resting-state activity in infants during sleep. We found five unique resting-states networks in the infant brain that encompassed the primary visual cortex, bilateral sensorimotor areas, bilateral auditory cortex, a network including the precuneus area, lateral parietal cortex, and the cerebellum as well as an anterior network that incorporated the medial and dorsolateral prefrontal cortex. These results suggest that resting-state networks driven by spontaneous signal fluctuations are present already in the infant brain. The potential link between the emergence of behavior and patterns of resting-state activity in the infant brain is discussed.development ͉ functional MRI ͉ spontaneous activity R ecent research on functional connectivity in the brain, in particular during resting-state conditions, has come to focus on low-frequency (Ͻ0.1 Hz), spontaneous fluctuations in the functional MRI (fMRI) signal. Discovered by Biswal et al. (1), it has been shown that systemwide networks in the resting brain are synchronized in time through intrinsic low-frequency signal fluctuations. Whereas early fMRI studies demonstrated synchronicity of intrinsic brain activity across hemispheres in primary sensory cortices (2, 3), succeeding studies have shown temporal synchronization in a resting-state network encompassing higher-order cortices (4). A systematic investigation of resting-state activity in the adult human brain was recently presented by Damoiseaux et al. (5). Using independentcomponent analysis (ICA), a data-driven explorative data analysis approach, they showed that there are numerous networks in the brain that are driven by spontaneous activity. Besides networks that are in part or fully described by the previously reported default mode (6) and task-positive network (7, 8), they found consistent patterns of resting-state activity in the visual cortex, sensorimotor areas, auditory areas, as well as extrastriate brain regions. These findings together with previous investigations on spontaneous activity suggest that the assumption that the brain during rest is idle and waiting to be triggered and respond to changes in the environment is not strictly valid. Rather, in addition to responding to changes in external stimuli or tasks, the brain is characterized by intrinsic dynamics in the form of coherent and spontaneous fluctuations, clustered together in networks that are credible from an anatomical and functional perspective.Interestingly, recent studies have presented evidence that spontaneous activity is relevant for human behavior. Momentary lapses of attention, affecting goal-oriented behavior on a global/ local selective attention task, were related to a fai...

The functional network topology of the adult human brain has recently begun to be noninvasively mapped using resting-state functional connectivity magnetic resonance imaging and described using mathematical tools originating from graph theory. Previous studies have revealed the existence of disproportionally connected brain regions, so called cortical hubs, which act as information convergence zones and supposedly capture key aspects of how the brain's architecture supports human behavior and how it is affected by disease. In this study, we present results showing that cortical hubs and their associated cortical networks are largely confined to primary sensory and motor brain regions in the infant brain. Our findings in infants stand in stark contrast to the situation found in adults where the majority of cortical hubs and hub-related networks are located in heteromodal association cortex. Our findings suggest that the functional network architecture in infants is linked to support tasks that are of a perception-action nature.

To study the patterns of supraspinal pain processing in neonates, we hypothesized that acute pain causes haemodynamic changes associated with activation of the primary somatosensory cortex. Forty preterm neonates at 28-36 weeks of gestation (mean=32.0) and at 25-42 h (mean=30.7) of age were studied following standardized tactile (skin disinfection) and painful (venipuncture) stimuli. Changes in regional cerebral haemodynamics were monitored by near infrared spectroscopy (NIRS) over both somatosensory cortices in 29 newborns, and over the contralateral somatosensory and occipital areas in 11 newborns. Heart rate (HR) and peripheral oxygen saturation (SaO2) were recorded simultaneously with NIRS parameters: oxygenated [HbO2], deoxygenated, and total hemoglobin. Tactile stimulation produced no changes in HR or SaO2. HR increased in the first 20s (p<0.001), while SaO2 decreased during the 40s after venipuncture (p<0.0001). Following tactile or painful stimulation, [HbO2] increased bilaterally regardless of which hand was stimulated (p<0.0001). Pain-induced [HbO2] increases in the contralateral somatosensory cortex (p<0.05) were not mirrored in the occipital cortex (p>0.1). Pain-related [HbO2] increases were more pronounced in male neonates (p<0.05 on left, p<0.001 on right), inversely correlated with gestational age (r=-0.53 on left, p<0.01; r=-0.42 on right, p<0.05) and directly correlated with postnatal age (r=0.75 on left, p<0.0001; r=0.67 on right, p<0.0001). Painful and tactile stimuli elicit specific haemodynamic responses in the somatosensory cortex, implying conscious sensory perception in preterm neonates. Somatosensory cortical activation occurs bilaterally following unilateral stimulation and these changes are more pronounced in male neonates or preterm neonates at lower gestational ages.

No abstract

No abstract

No abstract

and l\1s. \lonika (iiinlncr and \Is. Claudia \\'ohlfarlh fnr 1hc fa11l1k" lcchniral assistam.:L'. J5. This wnrk was suppnrlcd by lk111sd1c Forsd111ngsgcmcinschafl (SFB 147).

Recent progress in functional neuroimaging research has provided the opportunity to probe at the brain's intrinsic functional architecture. Synchronized spontaneous neuronal activity is present in the form of resting-state networks in the brain even in the absence of external stimuli. The objective of this study was to investigate the presence of resting-state networks in the unsedated infant brain born at full term. Using functional MRI, we investigated spontaneous low-frequency signal fluctuations in 19 healthy full-term infants. Resting-state functional MRI data acquired during natural sleep was analyzed using independent component analysis. We found five resting-state networks in the unsedated infant brain born at full term, encompassing sensory cortices, parietal and temporal areas, and the prefrontal cortex. In addition, we found evidence for a restingstate network that enclosed the bilateral basal ganglia. It is well known that the brain's energy expenditure is considerably larger than what is to be expected from its weight alone. Similar observations have been made in the infant brain (1). Moreover, it has also become apparent that the additional brain energy required to respond to changes in the environment is surprisingly small (2). Taken together, these observations have lead researchers to conclude that a large amount of the brain's activity is spent on tasks that as of yet is unaccounted for (3). Several theories related to the functional role of the brain's intrinsic activity have been proposed. Speculatively, intrinsic brain activity might be related to the neuronal activity necessary to retain a sustained level of maintenance and updating of information flow in the brain. To this end, recent development in functional MRI (fMRI) research has provided the opportunity to gain insights into the brain's intrinsic functional architecture by recording spontaneous, low-frequency blood oxygenation level dependent (BOLD) fMRI signal changes that are present during rest, i.e. in absence of any overt behavior (see Ref. 4 for a recent review). Several studies have shown that spontaneous changes in resting-state fMRI activity is related to the changes in neuronal activity (5,6) and that signal synchronicity across widely separated brain areas exist within multiple so-called resting-state networks in the adult brain (7). Previous reports have shown that functional connectivity in the format of resting-state networks in the adult brain spans brain regions that are involved in sensory perception (8 -10), language (11), and in the so-called default-mode network (12-14). The default-mode network is believed to be involved in different aspects of self-referential mental efforts (see Ref. 15; for a recent review on the mental capabilities of the newborn infant see Ref. 16). Recently, a number of studies have addressed the possibility to use resting-state functional connectivity as a biomarker for neurologic deficits in spatial neglect after stroke in the parietal cortex (17) as well as its potential role ...