Information-theoretic characterization of concurrent activity of neural spike trains

The analysis of massively parallel spike train recordings facilitates investigation of communications and synchronization in neural networks. In this work we develop and evaluate a measure of concurrent neural activity, which is based on intrinsic firing properties of the recorded neural units. An overall single neuron activity is unfolded in time and decomposed into working and non-firing state, providing a coarse, binary representation of the neurons functional state. We propose a modified measure of mutual information to reflect the degree of simultaneous activation and concurrency in neural firing patterns. The measure is shown to be sensitive to both correlations and anti-correlations, and it is normalized to attain a fixed bounded index which makes it interpretable. Finally, the measure is compared with widely used indexes of spike train correlation. The estimate of all measures is carried out in controlled experiments with synthetic Poisson spike trains and their corresponding surrogate datasets to asses its statistical significance

A Measure of Concurrent Neural Firing Activity Based on Mutual Information

Multiple methods have been developed in an attempt to quantify stimulus-induced neural coordination and to understand internal coordination of neuronal responses by examining the synchronization phenomena in neural discharge patterns. In this work we propose a novel approach to estimate the degree of concomitant firing between two neural units, based on a modified form of mutual information (MI) applied to a two-state representation of the firing activity. The binary profile of each single unit unfolds its discharge activity in time by decomposition into the state of neural quiescence/low activity and state of moderate firing/bursting. Then, the MI computed between the two binary streams is normalized by their minimum entropy and is taken as positive or negative depending on the prevalence of identical or opposite concomitant states. The resulting measure, denoted as Concurrent Firing Index based on MI (CFIMI), relies on a single input parameter and is otherwise assumption-free and symmetric. Exhaustive validation was carried out through controlled experiments in three simulation scenarios, showing that CFIMI is independent on firing rate and recording duration, and is sensitive to correlated and anti-correlated firing patterns. Its ability to detect non-correlated activity was assessed using ad-hoc surrogate data. Moreover, the evaluation of CFIMI on experimental recordings of spiking activity in retinal ganglion cells brought insights into the changes of neural synchrony over time. The proposed measure offers a novel perspective on the estimation of neural synchrony, providing information on the co-occurrence of firing states in the two analyzed trains over longer temporal scales compared to existing measures

The Effect of Adherence to the Mediterranean Diet on Late-Life Cognitive Disorders: A Systematic Review

Objectives: Although some results are conflicting, numerous investigations have demonstrated that the Mediterranean Diet (MedDiet) has positive effects on brain health. This review intends to provide an update on the scientific evidence regarding the effects of adherence to the MedDiet on late-life cognitive disorders. Design: A systematic review was performed. The PubMed and Scopus databases were searched for longitudinal studies and randomized controlled trials (RCTs) published between the databases’ inceptions and May 4, 2020. PRISMA guidelines were followed; the quality of the studies was assessed using version 2 of the Cochrane risk-of-bias tool for the RCTs and the Newcastle-Ottawa Scale for the longitudinal studies. The results are reported descriptively. Settings and Participants: Middle-aged and older adults. Measures: The review's principal outcomes were cognitive decline, cognitive performance and function, Mild Cognitive Impairment (MCI), Alzheimer's disease (AD), and dementia. Results: Forty-five of the 995 articles retrieved from the databases met our criteria. Seven were RCTs and 38 were longitudinal studies. Overall the studies showed that the MedDiet has some protective effects on cognitive decline. As far as cognition domains were concerned, the MedDiet was associated only with improved global cognition. The results were mixed for MCI and AD. There was no evidence that it has a beneficial effect on dementia. Conclusions and Implications: The review's analysis confirmed that adherence to the MedDiet is associated with some improvement in cognitive health. The heterogeneity of the scoring systems assessing adherence to the MedDiet and of the modalities evaluating the cognitive outcomes has played no small role in the differences emerging in the results and has hindered efforts to interpret them. Although other interventional studies are warranted to confirm the efficacy of the MedDiet in preventing cognitive disorders, the results show that it can be considered part of a multifactorial approach to improve late-life cognitive function. © 2020 AMDA – The Society for Post-Acute and Long-Term Care Medicin

Effects of fructooligosaccharide and whey protein concentrate on the viability of starter culture in reduced-fat Probiotic yogurt during storage

WOS: 000249496900015PubMed ID: 17995644Viability of yogurt starter cultures and Bifidobacterium animalis was assessed during 28 d storage in reduced-fat yougurts containing 1.5% milk fat supplemented with 1.5% fructooligosaccharide or whey protein concentrate. These properties were examined in comparison with control yogurts containing 1.5% and 3% milk fat and no supplement. Although fructooligosaccharide improved the viability of Streptococcus thermophilus, Lactobacillus delbrueckii subs. bulgaricus, and Bifidobacterium animalis, the highest growth was obtained when milk was supplemented with whey protein concentrate in reduced-fat yogurt (P < 0.05). Supplementation with 1.5% whey protein concentrate in reduced-fat yogurt increased the viable counts of S. thermophilus, L. delbrueckii subs. bulgaricus, and B. animalis by 1 log cycle in the 1st week of storage when compared to control sample. Similar improvement in the growth of both yogurt bacteria and B. animals was also obtained in the full-fat yogurt containing 3% milk fat and no supplement. Addition of whey protein concentrate also resulted in the highest content of lactic and acetic acids (P < 0.05). A gradual increase was obtained in organic acid contents during the storage