Biology subjects

Peylo, C.

Publications and source records attributed to Peylo, C..

3 recordsLinked to original sources

bioRxiv2025

Transcranial direct current stimulation over the frontal eye field has no effect on visual search performance

Top-down attention for the goal-directed (de-)prioritization of information is fundamental for successful everyday-life behavior and poses tremendous problems when negatively impacted by disease. Attention-targeting enhancement and rehabilitation attempts using non-invasive brain stimulation techniques like transcranial direct current stimulation (tDCS) are therefore of major importance. tDCS-driven excitation of the left frontal eye field (FEF; a key region within fronto-parietal attention networks) has recently been suggested to improve attention-guided visual search with stronger effects for lower baseline performers. Here, we report two preregistered tDCS experiments that tested 1) whether the previously observed visual search improvement could be boosted through stimulation over the allegedly more dominant right FEF and 2) whether tDCS-related visual search improvements might depend on search field size. To this end, in experiments one and two, N=29 and N=31 healthy participants performed a visual search task, in which they searched for an upside-down T amongst upright Ts and Ls within small or large search fields, before and during the application of anodal (excitatory) or sham (control) tDCS over the right or left FEF, respectively. In contrast to previous studies, in both experiments (i.e., independent of stimulation site and search field size) we found neither tDCS-specific (anodal > sham) visual search improvements, nor stimulation-specific baseline dependencies (larger improvements for lower baseline performers were observed in both tDCS conditions, suggesting rather stimulation-unspecific effects like regression to the mean). Together, our results provide evidence against reliable top-down attention-guided visual search improvements through FEF tDCS.

neuroscience↗

bioRxiv2025

Impact of Aging on Theta-Phase Gamma-Amplitude Coupling During Learning: A Multivariate Analysis

Aging is associated with cognitive decline and memory impairment, but the underlying neural mechanisms remain unclear. Phase-amplitude coupling (PAC) between mid-frontal theta (5 Hz) and occipital gamma (>30 Hz) oscillations is a proposed marker for parallel storage of multiple items in working memory. However, research has mainly focused on young individuals and epilepsy patients, with only a few studies on aging populations. Moreover, these studies have relied on univariate PAC methods, which can be flawed by potential spurious or biased PAC estimates due to non-stationarity of EEG signals. Additionally, these methods typically assess PAC at the level of individual electrodes, potentially overlooking the broader functional significance of theta-gamma coupling in coordinating neural activity across distant brain regions. To address these gaps, we employed multivariate PAC (mPAC) through generalized eigendecomposition (GED) analysis, which avoids the pitfalls of non-sinusoidal oscillations. 113 young and 117 older healthy participants engaged in a sequence learning paradigm (6423 sequence repetitions, 55944 stimuli), in which they learned a fixed sequence of visual stimuli over repeated observations, allowing us to track the mPAC during the incremental process of learning. Behavioral results revealed that younger participants learned significantly faster than older participants. Neurophysiological data showed that mPAC increased over the course of learning in both age groups and could identify fast and slow learners. However, older participants exhibited lower mPAC compared to younger counterparts, which suggest compromised parallel storage of items in working memory in older age. Finally, stratification analysis revealed that mPAC effects persist across performance groups with similar mid-frontal theta levels, suggesting that theta alone does not account for these effects. These findings shed light on the age-related differences in memory formation processes and may guide interventions to enhance memory performance in older adults and slow learners.

neuroscience↗

bioRxiv2023

Who you gonna call? TMS-induced inhibition of the left premotor cortex acts as a Bayesian Ghost Buster by altering illusory social perception

Communicative actions from one person are used to predict another persons response. However, in some cases, these predictions can outweigh the processing of sensory information and lead to illusory social perception such as seeing two people interact, although only one is present (i.e., seeing a Bayesian ghost). We applied either inhibitory brain stimulation over the left premotor cortex (i.e., real TMS) or sham TMS. Then, participants indicated the presence or absence of a masked agent that followed a communicative or individual gesture of another agent. As expected, participants had more false alarms (i.e., Bayesian ghosts) in the communicative than individual condition in the sham TMS session and this difference between conditions vanished after real TMS. In contrast to our hypothesis, the number of false alarms increased (rather than decreased) after real TMS. These pre-registered findings confirm the significance of the premotor cortex for social action predictions and illusory social perception. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/526257v2_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1b5812corg.highwire.dtl.DTLVardef@1338411org.highwire.dtl.DTLVardef@123b84eorg.highwire.dtl.DTLVardef@192a4b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISocial predictions can outweigh sensory information and lead to illusory perception C_LIO_LIPremotor cortex is linked to the illusory social perception of a Bayesian ghost C_LIO_LITMS over premotor cortex modulates how social predictions influence our perception C_LI

neuroscience↗