Biology subjects

Gulyas, A.

Publications and source records attributed to Gulyas, A..

3 recordsLinked to original sources

bioRxiv2025

Signed motif analysis of the Caenorhabditis elegans neuronal network reveals positive feedforward and negative feedback loops

BackgroundNervous systems are complex biological networks with largely unknown structural and functional characteristics. Motif analysis is a robust tool that can reveal the unique aspects of connectivity in a complex network. An ideal candidate for motif analysis is the connectome of the nematode Caenorhabditis elegans, which is the first fully reconstructed nervous system. ResultsWe performed, for the first time, edge-polarity based signed motif analysis on the C. elegans connectome using recent data on the connection signs of this network and a novel structure-preserving randomization method. We identified 56 significantly over- and 1 underrepresented three-node signed motifs and revealed that certain motifs (e.g., positive feedforward, negative feedback, disinhibitory feedback, and incoherent feedforward loops) are overabundant in the C. elegans connectome. We further distinguished nodes by their corresponding neuron modalities (e.g., sensory vs. motor neurons), and found that each significant feedforward and feedback loop has a characteristic neuronal layout. ConclusionsOur findings demonstrate the importance and potential of signed motif analysis in understanding biological networks. The motif enumeration tool and definition system we developed can be used to analyze signed motifs in other complex networks.

systems biology↗

bioRxiv2019

Distinct synchronization, cortical coupling and behavioural function of basal forebrain cholinergic neuron types

Basal forebrain cholinergic neurons (BFCN) densely innervate the forebrain and modulate synaptic plasticity, cortical processing, brain states and oscillations. However, little is known about the functional diversity of cholinergic neurons and whether distinct types support different functions. To examine this question we recorded BFCN in vivo, to examine their behavioral functions, and in vitro, to study their intrinsic properties. We identified two distinct types of BFCN that markedly differ in their firing modes, synchronization properties and behavioral correlates. Bursting cholinergic neurons (BFCNBURST) fired in zero-lag synchrony with each other, phase-locked to cortical theta activity and fired precisely timed bursts of action potentials after reward and punishment. Regular firing cholinergic neurons (BFCNREG) were found predominantly in the posterior basal forebrain, displayed strong theta rhythmicity (5-10 Hz), fired asynchronously with each other and responded with precise single spikes after behavioral outcomes. In an auditory detection task, synchronization of BFCNBURST neurons to auditory cortex predicted the timing of mouse responses, whereas tone-evoked cortical coupling of BFCNREG predicted correct detections. We propose that cortical activation relevant for behavior is controlled by the balance of two cholinergic cell types, where the precise proportion of the strongly activating BFCNBURST follows an anatomical gradient along the antero-posterior axis of the basal forebrain.

neuroscience↗

bioRxiv2018

Inner Asian maternal genetic origin of the Avar period nomadic elite in the 7th century AD Carpathian Basin

After 568 AD the nomadic Avars settled in the Carpathian Basin and founded their empire, which was an important force in Central Europe until the beginning of the 9th century AD. The Avar elite was probably of Inner Asian origin; its identification with the Rourans (who ruled the region of todays Mongolia and North China in the 4th-6th centuries AD) is widely accepted in the historical research.\n\nHere, we study the whole mitochondrial genomes of twenty-three 7th century and two 8th century AD individuals from a well-characterised Avar elite group of burials excavated in Hungary. Most of them were buried with high value prestige artefacts and their skulls showed Mongoloid morphological traits.\n\nThe majority (64%) of the studied samples mitochondrial DNA variability belongs to Asian haplogroups (C, D, F, M, R, Y and Z). This Avar elite group shows affinities to several ancient and modern Inner Asian populations.\n\nThe genetic results verify the historical thesis on the Inner Asian origin of the Avar elite, as not only a military retinue consisting of armed men, but an endogamous group of families migrated. This correlates well with records on historical nomadic societies where maternal lineages were as important as paternal descent.

genomics↗