Biology subjects

Galan-Garcia, L.

Publications and source records attributed to Galan-Garcia, L..

4 recordsLinked to original sources

bioRxiv2025

Exploring the likelihood of the membrane pollution hypothesis with a physiologically plausible biophysical model.

Epilepsy affects more than 52 million people worldwide and has been known since ancient times. Despite this long history, available therapeutic methods--both pharmacological and non-pharmacological--fail to control seizures in over 10% of patients. At the same time, there exists a diversity of theories regarding the fundamental mechanisms underlying epilepsy. Understanding the biophysical basis of the simplest manifestation of epileptic activity--the paroxysmal depolarization shift (PDS)--could therefore be highly valuable. Prevailing ideas consider PDS as exaggerated synaptic excitatory potentials, but experimental evidence shows that PDS can be generated in isolated neurons devoid of synaptic input. Ulrich Altrup proposed an alternative view, suggesting that PDS represent aberrantly large pacemaker potentials rather than giant excitatory postsynaptic potentials. Theoretical work by Hernandez-Caceres and Brenes supported this concept, demonstrating a bifurcation-like transformation from physiological pacemaker potentials to PDS and finally to long-duration sustained depolarizations. According to Altrups membrane pollution hypothesis (MPH), epileptic activity emerges as a consequence of incorporating amphiphilic pollutants into neuronal membranes, which leads to an increase in membrane micro-viscosity. Using a biophysically sound model for pacemaker activity, we explored the possibility of eliciting PDS through increased membrane micro-viscosity. Provided results suggest that this is theoretically plausible. Further experimental and theoretical research is needed to refine details of the MPH and to develop new strategies for combating epilepsy.

neuroscience↗

bioRxiv2024

EEG Signatures of COVID-19 Survival compared to close contacts and the Cuban EEG normative database

BackgroundThe EEG constitutes a powerful neuroimaging technique for assessing functional brain impairment in COVID-19 patients. ObjectiveThe current investigation compared the EEG among COVID-19 survivors, close contacts and the Cuban EEG normative database, using semi-quantitative visual EEG inspection, quantitative and the current source density measures EEG analysis. MethodsThe resting-state EEG activity, quantitative QEEG, and VARETA inverse solution, were evaluated in 173 subjects: 87 patients confirmed cases by the positive reverse transcription polymerase chain reaction (RT-PCR), 86 close contacts (negative PCR) and the Cuban EEG normative database. All patients were physical, neurological, and clinically assessed using neurological retrospective survey and version 2.1 of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). ResultsThe GTE score showed significant differences in terms of frequency scores of backgrounds rhythmic activity, diffuse slow activity, and focal abnormality. The QEEG analysis showed a pattern of abnormality with respect to the Cuban EEG normative values, displaying an excess of alpha and beta activities in the fronto-central-parietal areas in both groups. The anomalies, of COVID-19 patients and close contacts, differs in the right fronto-centro parietal area. The COVID 19 group differed-s from the close control group in theta band of the right parieto-central. The symptomatic group of COVID-19 patients differs from asymptomatic patients in delta and theta activities of the parieto-central region. The sources of activation using VARETA showed a difference in cortical activation patterns at alpha and beta frequencies in the groups studied with respect to the normative EEG database. In beta frequency were localized in right middle temporal gyrus in both groups and right angular gyrus in Covid 19 group only. In alpha band, the regions were the left supramarginal gyrus for Covid 19 group and the left superior temporal gyrus for Control group. Greater activation was found in the right middle temporal gyrus at alpha frequency in COVID-19 patients than in their close contacts. ConclusionsBrain functions are impaired in long COVID-19 patients. QEEG and VARETA permit us to comprehend the susceptibility of particular brain regions exposed to viral illness. HighlightsO_LIBackground frequency abnormalities diffuse slow activity and focal abnormality associated with a pattern of excess oftheta, alpha and beta energies in in the right fronto-centro-parietal regions in QEEG analysis characterizedCOVID-19 patients. C_LIO_LIPatients with COVID-19 show more alpha and beta EEG activities related to normative EEG database. C_LIO_LIPatients with COVID-19 and close contacts show high cortical activation in temporo-parietal areas in alpha and beta bands compared to normative EEG database. C_LIO_LIPatients with COVID-19 (positive PCR) have high activation in the right middle frontal gyrus for alpha band related to close contacts. C_LI

neuroscience↗

bioRxiv2022

Co-fluctuations of neural activity define intra-V1 networks related to perceptual organization

Using functional resonance imaging (fMRI), we studied the relationship between perceptual organization and network topology within the primary visual cortex (V1). Twenty-six humans (male and female) were recorded during active observation of two Global and two Local Navon letters. Correlations between fMRI fluctuations from different V1 sites were measured (after removing stimulus-evoked signals) in windows specific to each condition. Intra-V1, like brain-wide networks, presented an overall decrease of correlations during stimulation compared to baseline and increased statistical dimensionality. Massive edgewise testing and network based-statistics (both corrected by FDR) identified differences between conditions of connection strengths that were mapped to the visual field. Global letters elicited long links mainly connecting V1 sites mapping the lower left/right visual quadrants. Shorter links were associated with Local letters, primarily mapped within the lower-left visual quadrant. Frequently link lengths exceeded V1 population receptive field sizes. These connections were not observed in the time-locked (feedforward) responses shared across participants. Thus, these networks reflect activity idiosyncratic to each participant, possibly generated by interactions within or feedback to V1. Perception would sculpt V1 connectivity, with specific increases in link strengths (in a background of decreases). These findings could help shed light on V1 as a "cognitive blackboard".

neuroscience↗

bioRxiv2022

Harmonized-Multinational qEEG Norms (HarMNqEEG)

This paper extends our frequency domain quantitative electroencephalography (qEEG) methods pursuing higher sensitivity to detect Brain Developmental Disorders. Prior qEEG work lacked integration of cross-spectral information omitting important functional connectivity descriptors. Lack of geographical diversity precluded accounting for site-specific variance, increasing qEEG nuisance variance. We ameliorate these weaknesses. i) Create lifespan Hermitian Riemannian multinational qEEG norms for cross-spectral tensors. These norms result from the HarMNqEEG project fostered by the Global Brain Consortium. We calculate the norms with data from 9 countries, 12 devices, and 14 studies, including 1564 subjects. Instead of raw data, only anonymized metadata and EEG cross-spectral tensors were shared. After visual and automatic quality control developmental equations for the mean and standard deviation of qEEG traditional and Hermitian Riemannian descriptive parameters were calculated using additive mixed-effects models. We demonstrate qEEG "batch effects" and provide methods to calculate harmonized z-scores. ii) We also show that the multinational harmonized Hermitian Riemannian norms produce z-scores with increased diagnostic accuracy to predict brain dysfunction at school-age produced by malnutrition only in the first year of life. We provide data and software for constructing norms. iii) We offer open code and data to calculate different individual z-scores from the HarMNqEEG dataset. These results contribute to developing bias-free, low-cost neuroimaging technologies applicable in various health settings. HighlightsO_LIWe create lifespan Hermitian Riemannian qEEG norms for cross-spectral tensors. C_LIO_LIThe norms are based on 9 countries, 12 devices, and 14 studies, with 1564 subjects. C_LIO_LIWe demonstrate qEEG "batch effects", providing harmonization methods to remove them. C_LIO_LIMultinational harmonized z-scores increase diagnostic accuracy of brain dysfunction. C_LIO_LIData and software are available for norm and individual z-scores calculation. C_LI

neuroscience↗