Binding Mechanisms in Visual Perception and Their Link With Neural Oscillations: A Review of Evidence From tACS

Neurophysiological studies in humans employing magneto- (MEG) and electro- (EEG) encephalography increasingly suggest that oscillatory rhythmic activity of the brain may be a core mechanism for binding sensory information across space, time, and object features to generate a unified perceptual representation. To distinguish whether oscillatory activity is causally related to binding processes or whether, on the contrary, it is a mere epiphenomenon, one possibility is to employ neuromodulatory techniques such as transcranial alternating current stimulation (tACS). tACS has seen a rising interest due to its ability to modulate brain oscillations in a frequency-dependent manner. In the present review, we critically summarize current tACS evidence for a causal role of oscillatory activity in spatial, temporal, and feature binding in the context of visual perception. For temporal binding, the emerging picture supports a causal link with the power and the frequency of occipital alpha rhythms (8–12 Hz); however, there is no consistent evidence on the causal role of the phase of occipital tACS. For feature binding, the only study available showed a modulation by occipital alpha tACS. The majority of studies that successfully modulated oscillatory activity and behavioral performance in spatial binding targeted parietal areas, with the main rhythms causally linked being the theta (~7 Hz) and beta (~18 Hz) frequency bands. On the other hand, spatio-temporal binding has been directly modulated by parieto-occipital gamma (~40–60 Hz) and alpha (10 Hz) tACS, suggesting a potential role of cross-frequency coupling when binding across space and time. Nonetheless, negative or partial results have also been observed, suggesting methodological limitations that should be addressed in future research. Overall, the emerging picture seems to support a causal role of brain oscillations in binding processes and, consequently, a certain degree of plasticity for shaping binding mechanisms in visual perception, which, if proved to have long lasting effects, can find applications in different clinical populations

Changes in pasture and cow milk compositions during a summer transhumance in the western Italian Alps

The changes occurring in pasture and milk compositions during summer grazing were studied following a transhumance of a dairy cattle herd in the western Italian Alps. During three consecutive grazing periods (P1, P2, and P3) the cows exploited, in sequence, mountain pastures located at 1200-1260 m a.s.l. (A1), alpine pastures at 2000-2200 m a.s.l. (A2), and then returned to A1 pastures. The botanical and nutritional compositions of pastures, as well as cow milk yield, gross composition and fatty acid (FA) profi le were assessed during the transhumance. Within the pastures, a cluster analysis allowed the recognition of five vegetation types and seven vegetation sub-types; their allocation and plant species composition differed among the exploited grazing areas. The average Pastoral Values were signifi cantly higher in the mountain (A1P1, A1P3) than in the alpine pastures (A2P2) due to the abundance of high- and medium-quality forage species such as Dactylis glomerata L., Polygonum bistorta L., and Festuca rubra s.l.. Nevertheless, the nutritional quality of the herbage offered to the animals did not differ between A1P1 and A2P2, while it was significantly higher in A1P3 due to a younger vegetation phenological stage. The nutritional parameters were found to be correlated to the pasture botanical composition and phenology: organic matter digestibility and net energy for lactation were correlated negatively to the phenological stage and the Specific Contribution (SC) of Poaceae and positively to the SC of Fabaceae and Asteraceae. Milk yield significantly declined while milk protein increased during the grazing season, following the advance of cows’ stage of lactation. Milk fat and lactose percentages did not vary significantly among the grazing periods. The same was also observed for milk FA, with the exception of palmitic acid, whose level was lower in A2P2 if compared to the other two periods. Significant correlations were found between the percentages of some FA in milk and the SC of the main botanical families of the grazed pastures. In particular, linoleic acid was negatively correlated with the SC of Poaceae and positively correlated with the SC of Fabaceae. Results showed that the changes in the nutritional composition of pastures depended on variations in pasture botanical composition and phenology at the time of grazing, and that such factors concurred with animal-related factors in affecting milk quality during the grazing season

Continuous Glucose Monitoring in Preterm Infants: The Role of Nutritional Management in Minimizing Glycemic Variability

Glycemic variability (GV) is common in preterm infants. In the premature population, GV is a risk factor for morbidity and mortality. Both hypo- and hyperglycemia can impair neurodevelopment. We investigated the impact of continuous versus intermittent tube enteral feeding on GV. In our prospective observational study, 20 preterm infants with a gestational age ≤ 34 weeks at either continuous or intermittent bolus full enteral feeding. For five days, continuous glucose monitoring (CGM) was utilized, which was achieved through the subcutaneous insertion of a sensor. A total of 27,532 measurements of blood glucose were taken. The mean amplitude of glycemic excursions did not differ between the two cohorts statistically. Continuous feeding resulted in higher positive values, increasing the risk of hypo- and hyperglycemia. Subjects who were small for their gestational age had a higher standard deviation during continuous feeding (p = 0.001). Data suggest that intermittent bolus nutrition is better for glycemic control than continuous nutrition. Nutritional management optimization of preterm infants appears to be critical for long-term health. In the future, CGM may provide a better understanding of the optimal glucose targets for various clinical conditions, allowing for a more personalized approach to management