Biology subjects

Grigoras, I.

Publications and source records attributed to Grigoras, I..

3 recordsLinked to original sources

bioRxiv2026

Effects of cholinergic potentiation on resting-state functional connectivity in healthy adults

Acetylcholine is a key attentional neuromodulator, yet its effects on large-scale organisation of resting-state networks remain poorly understood. Here, we investigated whether acute cholinergic potentiation with the acetylcholinesterase inhibitor donepezil modulates functional connectivity within and between resting-state networks involved in attention. Nineteen healthy young adults completed a double-blind, placebo-controlled crossover study using 7T resting-state functional MRI (rs-fMRI), with imaging performed before and after administration of donepezil or placebo. We tested whether donepezil altered functional connectivity within and between the dorsal attention, ventral attention, default mode, and frontoparietal networks and whether it improved attentional orienting in the same volunteers. Voxel-wise analysis revealed a significant donepezil-related increase in dorsal attention network connectivity within the left inferior parietal cortex. We did not observe donepezil-related changes within the ventral attention, default mode, or frontoparietal networks. Network-level analyses did not identify significant global changes in network strength. Exploratory analyses indicated reduced coupling between the dorsal attention and default mode networks following donepezil relative to placebo, although this result did not survive correction for multiple comparisons. Donepezil did not significantly improve attentional orienting at the group level. However, exploratory analyses suggested that greater donepezil-related enhancement of functional connectivity within the identified left inferior parietal cluster was associated with greater improvement in attentional orienting. These findings suggest that acute cholinergic potentiation does not globally enhance resting-state connectivity across attentional networks in healthy young adults. Instead, donepezil may selectively modulate localised dorsal attention network circuitry, particularly within left inferior parietal cortex, a region implicated in sensory integration and externally oriented cognition.

neuroscience↗

bioRxiv2025

Dual-site beta transcranial alternating current stimulation during a bimanual coordination task modulates functional connectivity between motor areas

BackgroundCommunication within brain networks depends on functional connectivity. One promising approach to modulate such connectivity between cortical areas is dual-site transcranial alternating current stimulation (tACS), which non-invasively applies weak alternating currents to two brain areas. Objectives/HypothesesIn the current study, we aimed to modulate inter-regional functional connectivity with dual-site tACS to bilateral primary motor cortices (M1s) during bimanual coordination and, in turn, alter behaviour. MethodsUsing functional magnetic resonance imaging (fMRI), we recorded participants brain responses during a bimanual coordination task in a concurrent tACS-fMRI design. While performing a slow and fast version of the task, participants received one of three types of beta (20 Hz) dual-site tACS over both M1s: in-phase, jittered-phase or sham, in a within-subject, repeated measures design. ResultsWhile we did not observe any significant tACS effects on behaviour, the study revealed a disruptive effect of in-phase tACS on interhemispheric connectivity. Additionally, the two active types of tACS (in-phase and jittered-phase) differed in the task-related M1 connectivity with other motor cortical regions, such as premotor cortex and supplementary motor area. Furthermore, individual E-field strengths were related to functional connectivity in the in-phase condition. ConclusionsDual-site beta tACS over both M1s altered functional connectivity between motor areas. However, this effect did not translate to the behavioural level, possibly due to compensatory mechanisms. HighlightsO_LIInterhemispheric connectivity between the primary motor cortices was targeted with dual-site beta tACS during bimanual coordination. C_LIO_LIIn-phase as compared to sham tACS disrupted interhemispheric connectivity during task performance. C_LIO_LIIn-phase and jittered-phase tACS led to different task-related functional connectivity patterns within the motor network. C_LIO_LIThe relationship between individual in-phase E-field strengths and interhemispheric connectivity depended on task demand. C_LIO_LIThere were no significant tACS effects on behavioural performance of bimanual coordination, possibly due to compensatory mechanisms. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/647211v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@17ecdd8org.highwire.dtl.DTLVardef@1fc5b25org.highwire.dtl.DTLVardef@c3df42org.highwire.dtl.DTLVardef@17671bb_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2019

Leptin and adiponectin dynamics at patients with rectal neoplasm - gender differences

Background.Numerous studies associate adipokines with colorectal malignancy, but few data deal with patients suffering exclusively of rectal carcinoma (RC). Aims. We evaluated leptin and adiponectin levels in RC patients compared to healthy population and their dynamics after surgery. Material and methods. Serum leptin and adiponectin were evaluated before surgery in 59 RC consecutive patients (38 males and 21 females), and in age and weight matched healthy controls. Measurements were repeated at 24, 72 hours and 7 days after surgery. Results. Adipokine levels were higher in women. Controls had higher leptin (32.{+/-}4.34 vs 9.51{+/-}1.73 ng/ml in women and 11{+/-}2.66 vs 2.54{+/-}0.39 ng/ml in men, p=0.00048 and 0.0032) and lower adiponectin (9{+/-}0.64 vs 11.85{+/-}1.02 {micro}g/ml in women and 7.39{+/-}0.51 vs 8.5{+/-}0.62 {micro}g/ml in men, p=0.017 and 0.019) than RC patients. Surgery caused an increase of leptin from 5.11{+/-}0.8 to 18.7{+/-}2.42 ng/ml, p=6.85 x 108, and a decrease of adiponectin from 9.71{+/-}0.58 to 7.87{+/-}0.47 {micro}g/ml, p=1.4 x 1010 for all RC patients and returned thereafter to the initial range at 7 days. Adipokines were correlated with body weight (BW). The significance of correlation persisted after surgery only in males, but disappeared in females. Adipokines were not modified by tumor position, presurgical chemoradiotherapy or surgical technique. Women with RC experiencing weight loss had higher adiponectin than women without weight modifications (p<0.05 at all time points). Conclusions. Adipokine levels of patients with RC differ from the healthy population, possibly reflecting an adaptation to disease. Adipokine modifications after surgery may be related to acute surgical stress. Whether leptin and adiponectin directly interact is not clear. Women have higher adipokine levels, more so after significant weight loss, but the strength of their correlation with BW decreases after surgery. These data suggest gender differences in the adipokine profile of RC patients which may find clinical applications.

cancer biology↗