Biology subjects

Luhrs, M.

Publications and source records attributed to Luhrs, M..

3 recordsLinked to original sources

bioRxiv2023

Successful Modulation of Temporoparietal Junction Activity and Stimulus-Driven Attention by fNIRS-based Neurofeedback - a Randomized Controlled Proof-of-Concept Study

The right temporoparietal junction (rTPJ) is a core hub in neural networks associated with reorienting of attention and social cognition. However, it remains unknown whether participants can learn to actively modulate their rTPJ activity via neurofeedback. Here, we explored the feasibility of functional near-infrared spectroscopy (fNIRS)-based neurofeedback in modulating rTPJ activity and its effect on rTPJ functions such as reorienting of attention and visual perspective taking. In a bidirectional regulation control group design, 50 healthy participants were either reinforced to up- or downregulate rTPJ activation over four days of training. Both groups showed an increase in rTPJ activity right from the beginning of the trainingbut only the upregulation group maintained this effect, while the downregulation group showed a decline from the initial rTPJ activation. This suggests a learning effect in the downregulation exclusively, making it challenging to draw definitive conclusions about the effectiveness of rTPJ upregulation training. However, we observed group-specific effects on the behavioral level. We found a significant group x time interaction effect in the performance of the reorienting of attention task and group-specific changes, with decreased reaction times (RTs) in the upregulation group and increased RTs in the downregulation group across all conditions after the neurofeedback training. Those with low baseline performance showed greater improvements. In the perspective-taking task, however, only time effects were observed that were non-group-specific.These findings demonstrate that fNIRS-based neurofeedback is a feasible method to modulate rTPJ functions with preliminary evidence of neurophysiologically specific effects, thus paving the way for future applications of non-invasive rTPJ modulation in neuropsychiatric disorders. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/532169v2_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1061186org.highwire.dtl.DTLVardef@168b06forg.highwire.dtl.DTLVardef@17795forg.highwire.dtl.DTLVardef@1215c6e_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIthe right temporoparietal junction (rTPJ) as a core hub for attentive and socio-cognitive functions is a promising target for neuromodulatory interventions C_LIO_LIfirst single-blinded, randomized controlled study demonstrates feasibility and effectiveness of the fNIRS-based neurofeedback training of the rTPJ in healthy adults C_LIO_LIsubjects are able to regulate the rTPJ with different learning characteristics C_LIO_LIfirst evidence of a neurophysiologically specific effect on stimulus-driven attention C_LIO_LIfindings have important implications for clinical translation of neurofeedback interventions targeting the rTPJ C_LI

neuroscience↗

bioRxiv2020

Guiding functional near-infrared spectroscopy optode-layout design using individual (f)MRI data: Effects on signal quality and sensitivity

Designing optode layouts is an essential step for functional near-infrared spectroscopy (fNIRS) experiments as the quality of the measured signal and the sensitivity to cortical regions-of-interest depend on how optodes are arranged on the scalp. This becomes particularly relevant for fNIRS-based brain-computer interfaces (BCIs), where developing robust systems with few optodes is crucial for clinical applications. Available resources often dictate the approach researchers use for optode-layout design. Here we compared four approaches that incrementally incorporated subject-specific magnetic resonance imaging (MRI) information while participants performed mental-calculation, mental-rotation and inner-speech tasks. The literature-based approach (LIT) used a literature review to guide the optode layout design. The probabilistic approach (PROB), employed individual anatomical data and probabilistic maps of functional MRI (fMRI)-activation from an independent dataset. The individual fMRI (iFMRI) approach used individual anatomical and fMRI data, and the fourth approach used individual anatomical, functional and vascular information of the same subject (fVASC). The four approaches resulted in different optode layouts and the more informed approaches outperformed the minimally informed approach (LIT) in terms of signal quality and sensitivity. Further, PROB, iFMRI and fVASC approaches resulted in a similar outcome. We conclude that additional individual MRI data leads to a better outcome, but that not all the modalities tested here are required to achieve a robust setup. Finally, we give preliminary advice to efficiently using resources for developing robust optode layouts for BCI and neurofeedback applications.

neuroscience↗

bioRxiv2020

Did I imagine that? The functional role of paracingulate cortex in reality monitoring

Reality monitoring describes our ability to distinguish between internally and externally generated experiences. Individuals show significant variation in this ability and impaired reality monitoring has been linked to the experience of hallucinations. We undertook two studies to investigate the association between reality monitoring and morphology of the paracingulate region of medial prefrontal cortex. In Study 1 we compared reality monitoring accuracy and functional connectivity within paracingulate cortex in groups of healthy controls (N=20) and patients with schizophrenia and hallucinations (N=19). Controls showed greater reality monitoring accuracy that was associated with resting-state functional connectivity between paracingulate, precuneus and occipital cortices, while reality monitoring in patients was associated with more lateral functional connectivity. In Study 2 we used real-time fMRI neurofeedback to obtain causal evidence for the role of the paracingulate cortex in reality monitoring. Healthy individuals received Active feedback from paracingulate cortex (N=21) or Sham feedback based on randomised signal (N=18). Active-group participants showed a specific behavioural effect of improved reality monitoring for Imagined items, as well as increases in both activity within the paracingulate region, and its posterior functional connectivity with precuneus and lateral parietal cortices, and occipital cortex. Our findings suggest reality monitoring in healthy individuals is causally supported by a paracingulate mediated flexible network including the precuneus. Network connectivity can be enhanced using neurofeedback and tracks with improved reality monitoring ability. In contrast, patients with schizophrenia may utilise a distinct and more lateral network which may explain observed sub-optimal reality monitoring accuracy, contributing to the experience of hallucinations. Significance StatementReality monitoring refers to our ability to distinguish imagination from our experiences in the outside world, and is linked both to hallucinations in schizophrenia as well as to the morphology of paracingulate cortex area of the brain. Here, we revealed less paracingulate involvement in the functional reality monitoring networks in patients with schizophrenia compared to healthy individuals. Thereafter, we used real-time fMRI neurofeedback to show that healthy individuals can learn to upregulate brain activity within the paracingulate cortex, with this resulting in both improved reality monitoring ability and changes in paracingulate functional connectivity. This suggests that paracingulate cortex activity and connectivity play a causal role in reality monitoring, with implications for both the understanding and treatment of hallucinations.

neuroscience↗