Biology subjects

Pari, R. K.

Publications and source records attributed to Pari, R. K..

3 recordsLinked to original sources

bioRxiv2026

Manipulating speech perception with amplitude-modulated kilohertz magnetic perturbation (AM-kTMP)

Speech perception has been hypothesized to exploit neural activity that entrains to the rhythmic properties of the utterance. Perceptual sensitivity varies with the phase of oscillatory activity induced by speech, and with an external oscillatory perturbation induced by transcranial alternating current stimulation (tACS) over the temporal lobe. Here we used a new form of non-invasive brain stimulation (NIBS), kilohertz transcranial magnetic perturbation (kTMP), in which a low frequency perturbation is created by the amplitude modulation (AM) of a continuous high-frequency carrier signal (3.5 kHz). As a magnetic induction method, kTMP can produce much higher electrical fields at the cortical surface than tACS and reduces cutaneous co-stimulation. Human participants (n=40) listened to sequences of rhythmic speech while receiving kTMP with an AM component of 3.125 Hz. The phasic modulation of perceptual sensitivity was greater during AM-kTMP than during sham stimulation, suggesting that AM-kTMP entrains neural activity underlying speech perception. Participants ratings of rhythmic sensations and other side effects did not differ between AM-kTMP and sham stimulation. Together with its reduced peripheral stimulation, our results highlight kTMP as a promising NIBS method for modulating frequency-specific brain dynamics in speech perception.

neuroscience↗

bioRxiv2026

Neurofeedback enhances a neural signature of selective attention to speech in cocktail-party settings

Understanding speech in noisy situations is challenging and often fails due to attentional rather than sensory deficits. We report here that neurofeedback can enhance a neural signature of selective attention to speech in a cocktail-party setting. Neural responses to speech were quantified in participants electroencephalogram (EEG) while they attended to one of two audiobooks, presented simultaneously. After each 22s-segment of speech, the participants N1 component was extracted from the temporal response function (TRF). The N1 component is known to be sensitive to attention. During a [~]49-min training session, N1 amplitude values were displayed visually to participants so that they could learn to strengthen their neural responses to target speech and minimise their responses to distracting speech. During neurofeedback training, we found an enhanced N1 component in the response to target audiobooks that was specific to EEG channels used to provide feedback, and not present in a control group that received sham feedback. At right-lateralised fronto-central channels, enhanced N1 components correlated with improvements in a measure of speech comprehension (multiple-choice content questions). These results indicate that neural responses to speech can be regulated through neurofeedback and open up new possibilities to train attentional listening in populations struggling to understand speech in noise.

neuroscience↗

bioRxiv2021

Neural dynamics of stroboscopic stimulation at different stimulation frequencies

Stroboscopic stimulation has been previously shown to induce visual hallucinations and altered states of consciousness, state by entraining the brain to the driving frequency, similar to those reported during the psychedelics although little systematic research exists on the effect of specific stimulation frequency on experience. The present study investigated the effects of different stroboscopic stimulation frequencies on neural dynamics, such as signal diversity (Lempel-Ziv complexity) and spectral power and attempted to relate these changes to self-reported changes in experiential content. The results indicated that the stimulation frequencies near the alpha band (8 - 12 Hz) caused the greatest increase across all neural measures, with 8 Hz consistently displaying the most pronounced results, relative to baseline. All tested frequencies led to an increase in all experiential dimensions, relative to baseline.

neuroscience↗