No abstract

Article ReuseItems deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.Non parametric directionality analysis -extension for removal of a single common predictor and application to time series. AbstractBackground. The ability to infer network structure from multivariate neuronal signals is central to computational neuroscience. Directed network analyses typically use parametric approaches based on auto-regressive (AR) models, where networks are constructed from estimates of AR model parameters. However, the validity of using low order AR models for neurophysiological signals has been questioned. A recent article introduced a non parametric approach to estimate directionality in bivariate data, non parametric approaches are free from concerns over model validity.New Method. We extend the non parametric framework to include measures of directed conditional independence, using scalar measures that decompose the overall partial correlation coefficient summatively by direction, and a set of functions that decompose the partial coherence summatively by direction. A time domain partial correlation function allows both time and frequency views of the data to be constructed. The conditional independence estimates are conditioned on a single predictor.Results. The framework is applied to simulated cortical neuron networks and mixtures of Gaussian time series data with known interactions. It is applied to experimental data consisting of local field potential recordings from bilateral hippocampus in anaesthetised rats.Comparison with Existing Method(s). The framework offers a non parametric approach to estimation of directed interactions in multivariate neuronal recordings, and increased flexibility in dealing with both spike train and time series data.Conclusions. The framework offers a novel alternative non parametric approach to estimate directed interactions in multivariate neuronal recordings, and is applicable to spike train and time series data

Introduction Centella asiatica is an herbal plant that contains phytochemicals that are widely believed to have positive effects on cognitive function. The adolescent stage is a critical development period for the maturation of brain processes that encompass changes in physical and psychological systems. However, the effect of C. asiatica has not been extensively studied in adolescents. The aim of this study was therefore to investigate the effects of a C. asiatica extract on the enhancement of learning and memory in adolescent rats.MethodsThe locomotor activity, learning, and memory were assessed by using open field test and water T‐maze test. This study also examined changes in neuronal cell morphology using cresyl violet and apoptosis staining. We also performed immunohistochemical study to analyse the expression of the glutamate AMPA receptor (α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid) GluA1 subunit and the GABA receptor (γ‐Aminobutyric Acid) subtype GABAA α1 subunit in the hippocampus of the same animals.ResultsWe found no significant changes in locomotor activity (p > 0.05). The water T‐maze data showed that 30 mg/kg dose significantly (p < 0.05) improved learning, memory, and the memory consolidation phase but had no effect on reversal learning (p > 0.05). Histological data revealed no neuronal morphological changes. Immunohistochemical analysis revealed increased expression of the AMPA GluA1 receptor subunit but there was no effect on GABAA receptor α1 subunit expression in the CA1 and CA2 subregions of the hippocampus.ConclusionsThe C. asiatica extract therefore improved hippocampus‐dependent spatial learning and memory in a dose‐dependent manner in rats through the GluA1‐containing AMPA receptor in the CA1 and CA2 sub regions of the hippocampus.

No abstract

Centella asiatica is notable for its wide range of biological activities beneficial to human health, particularly its cognitive enhancement and neuroprotective effects. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are ionotropic glutamate receptors mediating fast excitatory neurotransmission essential in long-term potentiation widely thought to be the cellular mechanism of learning and memory. The method of whole-cell patch-clamp was used to study the effect of the acute application of Centella asiatica extract on the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated spontaneous excitatory postsynaptic currents in the entorhinal cortex of rat brain slices. The respective low dose of test compounds significantly increased the amplitude of spontaneous excitatory postsynaptic currents while having no significant effects on the frequency. The findings suggested that Centella asiatica extract increased the response of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors at the postsynaptic level, revealing the potential role of Centella asiatica in modulating the glutamatergic responses in the entorhinal cortex of rat brain slices to produce cognitive enhancement effects.