Sabrina Brigadoi

Very preterm (VPT, ≤ 32 weeks gestational age) newborns often experience neurodevelopmental delays or impairments. Early detection of these difficulties may improve long-term outcomes. Standardized clinical scales may fail to identify subtle cognitive disturbances, whereas lab-based tasks can provide greater sensitivity. In addition, VPT infants typically show greater glycaemic variability at birth than full-term (FT) infants, which may affect neurodevelopment, although previous findings are inconsistent.This study investigated whether lab-based tasks assessing visual attention and visual short-term memory, alongside standardized developmental scales, could provide a more detailed understanding of cognitive development in VPT compared with FT infants. Furthermore, by continuously measuring glucose levels during the first postnatal week using a continuous glucose monitoring (CGM) device, the study examined how neonatal glucose variability relates to neurodevelopmental outcomes at 12 months corrected age (CA). Sixty VPT infants were enrolled, and 43 completed the 12-month follow-up; 31 FT infants served as controls. VPT infants performed worse than FT infants across cognitive, motor, and language domains, and group differences also emerged in the computerized tasks. Notably, tighter glycaemic control at birth was associated with memory performance at 12 months CA.

SignificanceVery preterm infants are prone to large fluctuations in their blood glucose concentration (BGC), i.e., they can experience episodes of hyper- and hypoglycemia, due to impaired glucose control. To date, the relationship among how specific regions of the brain respond to glycemic events has not been fully explored, and characterizing how glucose fluctuations affect region-specific functional connectivity at birth may provide insight into neurodevelopment and could help identify early biomarkers of brain vulnerability in very preterm infants.AimThe aim is to evaluate whether the differences in task-free functional connectivity (tfFC) patterns before and after experiencing several days of BGC fluctuations were correlated with changes in the glucose profile during this time interval.ApproachWe continuously monitored both glucose concentration with a continuous glucose monitoring device and brain hemodynamics with diffuse optical tomography in a group of very preterm newborns to conduct tfFC analysis (N=12).ResultsChanges in tfFC patterns between the left frontal and left parietal regions were found to be correlated with the standard deviation of the glucose profile, whereas changes between the central prefrontal cortex and the right prefrontal region were found to be correlated with the maximum value of glucose concentration.ConclusionsWe suggest that changes in the coupling of these brain areas during rest are dependent on and occur during exposures to glycemic changes in the preterm brain.

Lateral saccades represent a major source of noise and confounds, particularly for event‐related potentials (ERPs) that rely on hemispheric imbalances in neural activity elicited by lateralized stimuli during central fixation. These include lateralized ERPs such as the contralateral delay activity (CDA), which indexes visual working memory (VWM) load. Due to its relatively small amplitude and strict fixation requirement, the CDA is particularly vulnerable to contamination from eye movements, which usually cause the contaminated trial to be discarded. In this context, independent component analysis (ICA) offers an alternative to the traditional epoch rejection method, as it removes ocular artifacts without discarding entire trials. However, ICA's effectiveness may be limited if saccade‐related activity is not fully removed, or if trials in which participants directed their foveae toward a lateral target stimulus are retained, leading to bilateral representation. In the present study, we compared the efficacy of ICA and epoch rejection in preserving CDA features when participants were allowed to saccade. Participants were asked to memorize an array composed of a variable number of laterally displayed colored squares. In half of the experiment, participants had to keep their gaze at fixation, whereas they had to saccade toward the memoranda in the other half. The memory array was displayed for either 100 ms or 500 ms to examine how the post‐saccade physical availability of the memoranda influenced CDA amplitude and latency. The results showed that ICA correction preserved the quality and defining features of the CDA component as well as, or in some respects better than, epoch rejection. Notably, the post‐saccade physical availability of the memoranda affected the latency of the CDA, with shorter offset latency observed when the memoranda were exposed for 500 ms compared to 100 ms, likely reflecting post‐saccade retinotopic recoding of the memoranda.

Very preterm neonates are more prone to experience hyper and hypo-glycaemia after birth. To date, there is no available evidence on the local brain hemodynamic response to these glycemic changes. This study uses continuous glucose monitoring (CGM) and diffuse optical tomography (DOT) to investigate this issue. Sixty very preterm neonates were recruited and continuously monitored after birth with CGM and DOT for several days. Patients with only mild (Sensor glucose concentration (SGC) ≥ 48 mg/dL & ≤ 72 mg/dL) or severe (SGC ≤ 47 mg/dL) hypoglycaemia (N=17) were then selected for analysis. DOT data were reconstructed in three 10-minute windows throughout each hypoglycemic event: at the beginning of the event, after the minimum of hypoglycemia, and at the end of the event. Correlations and spatial consistencies were found between changes in blood volume and SGC during these time windows, suggesting a coupling between SGC and brain hemodynamics in very preterm newborns after birth.

Background: Directing attention to relevant visual objects while ignoring distracting stimuli is crucial for effective perception and goal-directed behavior. Event-related potential (ERP) studies using the additional-singleton paradigm have provided valuable insights into how the human brain processes competing salient stimuli by monitoring N2pc and PD, two event-related components thought to reflect target selection and distractor suppression, respectively. However, whether these components reflect the activity of a single or distinct neural mechanism remains controversial. Herein, we investigated the neural substrate of N2pc and PD by manipulating the vertical elevation of target and distractor relative to the visual horizontal meridian using two variants of the additional-singleton paradigm. Methods: In Experiment 1, participants searched for a shape singleton and identified the orientation of an embedded tilted bar while ignoring a color singleton. In Experiment 2, the tilted bars were removed and participants performed a shape search while ignoring a color singleton. Electroencephalogram (EEG) recordings at posterior sites (PO7/8) measured N2pc and PD components. Reaction times and ERP amplitudes were analyzed across conditions. Results: The results of both Experiments 1 and 2 showed that N2pc and PD responded in opposite ways to the manipulation of vertical elevation. N2pc was robust for targets in the lower visual hemifield and reversed in polarity (i.e., post-N2pc positivity ) for targets in the upper visual hemifield. Conversely, PD was more pronounced for distractors in the upper visual hemifield and nil for those in the lower visual hemifield. Critically, vertical elevation did not influence psychophysical estimates of search efficiency in either experiment, suggesting that the relationship between these components and their functional significance is less straightforward than previously thought. Conclusions: These results provide empirical support for the idea that N2pc and PD are influenced by the retinotopic organization of the visual cortex in a manner consistent with the neural and functional dissociation of target selection and distractor suppression in visual search.

Lateral saccades represent a major source of noise and confounds, particularly for event-related potentials (ERPs) that rely on hemispheric imbalances in neural activity elicited by lateralized stimuli during central fixation. These include lateralized ERPs such as the sustained posterior contralateral negativity (SPCN), which indexes visual working memory (VWM) load. Due to its relatively small amplitude and strict fixation requirement, the SPCN is particularly vulnerable to contamination from eye movements, which usually cause the contaminated trial to be discarded. In this context, independent component analysis (ICA) offers an alternative to the traditional epoch rejection method, as it removes ocular artifacts without discarding entire trials. However, ICA’s effectiveness may be limited if saccade-related activity is not fully removed or if stimulus timing undermines the lateralization required for SPCN measurement. In the present study, we compared the efficacy of ICA and epoch rejection in preserving SPCN features when participants were allowed to saccade. Participants were asked to memorize an array composed of a variable number of laterally displayed colored squares. In half of the experiment, participants had to keep their gaze at fixation, whereas they had to saccade towards the memoranda in the other half. The memory array was displayed for either 100 ms or 500 ms to examine how the post-saccade physical availability of the memoranda influenced SPCN amplitude and latency. The results were clear-cut in showing that, relative to epoch rejection, ICA correction preserved both quality and features of SPCN component. Notably, the post-saccade physical availability of the memoranda affected the latency of the SPCN, with shorter offset latency observed when the memoranda were exposed for 500 ms compared to 100 ms, likely reflecting post-saccade retinotopic remapping of the memoranda.

When humans move both hands simultaneously, bimanual coupling or interference can occur. The circles‐lines paradigm is used to study the bimanual coupling and interference effects: Participants simultaneously draw either lines or circles with both hands (congruent), or draw lines with one hand and circles with the other hand (incongruent condition). Despite extensive behavioral research on bimanual coupling with this paradigm, our knowledge of the neural circuitry involved remains limited. Here, we capitalized on the advantages provided by functional near‐infrared spectroscopy to unveil the neural substrates of bimanual coupling within an ecologically valid experimental setting. Behavioral results confirmed previous literature, showing that the shapes become more oval due to the interference between the hands, causing the circle to resemble a line and vice versa. Additionally, performance in the congruent condition correlated with performance in the incongruent condition. From a neural perspective, we observed greater activity in sensorimotor areas and the right premotor area during the incongruent compared to the congruent condition. A novel temporal analysis of the time course of oxyhemoglobin signals revealed that the right hemisphere reached maximum amplitude before the left during the incongruent condition and revealed differences between conditions in parietal areas, showing that bimanual interference is associated not only with motor areas but also with associative areas. Finally, right inferior parietal lobe activity correlated with bimanual performance, suggesting a role for this area in bimanual tasks when the motor program of one hand is influenced by sensorimotor information from the contralateral hand.