Biology subjects

Chang, K.-Y.

Publications and source records attributed to Chang, K.-Y..

4 recordsLinked to original sources

bioRxiv2025

Modulating Brain Perfusion, Functional Connectivity, and Metabolite Patterns through Theta Burst Transcranial Focused Ultrasound Stimulation

BackgroundTranscranial ultrasonic stimulation (TUS) is an emerging non-invasive neuromodulation technique with the potential to target both cortical and subcortical brain regions. This study investigates the effects of theta-burst TUS (tb-TUS), a neuromodulatory pattern characterized by bursts of pulses repeated at a theta frequency, on cerebral blood flow, functional connectivity, and metabolite concentrations in the primary motor cortex (M1). The aim of this study is to take a first step towards the mechanistic and methodological feasibility of tb-TUS at the M1 using multimodal neuroimaging. MethodsSeventeen healthy participants underwent a double-blind, sham-controlled crossover design, receiving both active and sham tb-TUS to the left M1 over three days. Multimodal MRI, including pseudo-continuous arterial spin labeling (PCASL), resting-state functional MRI (rs-fMRI), and magnetic resonance spectroscopy (MRS), was conducted at baseline, pre-, and post-stimulation. Acoustic simulations and finger-tapping BOLD-peak signal guided individualized TUS targeting. ResultsActive tb-TUS significantly reduced cerebral blood flow (p < .001) and within-region functional connectivity (p < .001) in the M1 compared to sham stimulation. A non-significant trend towards decreased GABA was observed, with no significant session x condition interaction found for GABA, Glutamate, or Glx concentrations. ConclusionThis pilot study demonstrates that tb-TUS of the M1 induces reductions in cerebral blood flow and functional connectivity in healthy participants. Our findings indicate that tb-TUS may be mitigating neural hyperactivity patterns, but preliminary studies so far arrive at differing results, highlighting the need for further research to replicate our findings, elucidate the underlying mechanisms, and optimize stimulation protocols.

physiology↗

bioRxiv2025

Contralateral Prefrontal and Network Engagement during Left DLPFC 10 Hz rTMS: An Interleaved TMS-fMRI Study in Healthy Adults

BackgroundHigh-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) serves as an effective treatment for major depression and other psychiatric disorders. Despite its growing clinical application, the neural mechanisms by which prefrontal rTMS exerts its therapeutic effects remain incompletely understood. To address this gap, we investigated the immediate blood-oxygen-level-dependent (BOLD) activity during 600 stimuli of left DLPFC 10 Hz rTMS in healthy individuals using interleaved TMS-fMRI. MethodsIn a crossover design, 17 healthy subjects received 10 Hz rTMS (60 trains with 9-second intertrain intervals) over the left DLPFC at 40% and 80% of their resting motor threshold (rMT) inside the MR scanner. Results10 Hz rTMS over the left DLPFC elicited BOLD responses in prefrontal regions, cingulate cortex, insula, striatum, thalamus, as well as auditory and somatosensory areas. Notably, our findings revealed that 10 Hz rTMS effects were lateralized towards the contralateral (right) DLPFC. Dose-response effects (40% vs. 80% rTMS) were exclusively observed in contralateral subcortical regions, whereas dose-responses within the DLPFC showed substantial inter-individual variability. ConclusionsThe 10 Hz rTMS protocol used in this study induced distinct target engagement and propagation patterns in the prefrontal cortex. These patterns differ from our previous interleaved TMS-fMRI findings using 600 stimuli of left DLPFC intermittent theta burst stimulation (iTBS) at the same intensities. Thus, interleaved TMS-fMRI emerges as a valuable method for comparing clinical prefrontal rTMS protocols regarding their immediate effect on brain circuits in order to differentiate their action mechanisms and to potentially inform clinical applications.

neuroscience↗

bioRxiv2024

Neurotrophic factor Neuritin modulates T cell electrical and metabolic state for the balance of tolerance and immunity

The adaptive T cell response is accompanied by continuous rewiring of the T cells electric and metabolic state. Ion channels and nutrient transporters integrate bioelectric and biochemical signals from the environment, setting cellular electric and metabolic states. Divergent electric and metabolic states contribute to T cell immunity or tolerance. Here, we report that neuritin (Nrn1) contributes to tolerance development by modulating regulatory and effector T cell function. Nrn1 expression in regulatory T cells promotes its expansion and suppression function, while expression in the T effector cell dampens its inflammatory response. Nrn1 deficiency causes dysregulation of ion channel and nutrient transporter expression in Treg and effector T cells, resulting in divergent metabolic outcomes and impacting autoimmune disease progression and recovery. These findings identify a novel immune function of the neurotrophic factor Nrn1 in regulating the T cell metabolic state in a cell context-dependent manner and modulating the outcome of an immune response.

immunology↗

bioRxiv2016

Stimulus visibility controls the balance between attention-induced changes in contrast appearance and decision bias

While attention is known to improve information processing, whether attention can alter visual appearance has been a cornerstone of debate for 100+ years. Although recent studies suggest that attention can alter appearance, it has been argued that the reported appearance changes reflect response bias. Here, we provide a resolution to this debate by showing that attention has different effects on appearance and response bias depending on stimulus visibility. In a contrast judgment task where the contrast of attended and unattended stimuli varied across a full range of contrast values, human participants exhibited a substantial amount of response bias to the attended stimulus, when stimuli were hard to see. However, when stimuli were easier to see, response bias decreased and attention primarily increased perceived contrast. These results help constrain philosophical arguments about the cognitive penetrability of perception and reconcile the long-standing debate about the attention effect on appearance and response bias.

neuroscience↗