Biology subjects

Ku, Y.

Publications and source records attributed to Ku, Y..

17 recordsLinked to original sources

bioRxiv2026

Rhythmic motor activity alleviates auditory attentional blinks

Effective sensory processing relies on both attention and the motor system, yet whether motor activity could provide attention-like functions to regulate perception remains unknown. We hypothesized that rhythmic motor signals could provide phasic regulation of prioritizing and sampling perceptual targets. Using an auditory attentional blink paradigm that created a temporal deficit in selective attention, we found that temporally aligned finger tapping improved the probe detection during the attentional blink window but impaired performance when attentional resources were abundant. Furthermore, transcranial alternating current stimulation (tACS) over the right sensorimotor cortex alleviated attentional blink when the probe was close to the peak of the stimulation, whereas stimulation over the left aggravated attentional blink when the probe was close to the trough. These results suggest that the motor system is a resource-dependent rhythmic regulator of attentional sampling. Motor signals can override attentional bottlenecks, suggesting the motor system as an active shaper of cognitive processes.

neuroscience↗

bioRxiv2024

Load-dependent and load-independent effects on longitudinal motor training in human continuous hand movements

Motor learning involves complex interactions between the cognitive and sensorimotor systems, which is susceptible to different levels of task load. While the mechanism underlying load-dependent regulations in cognitive functions has been extensively investigated, their influence on downstream execution in motor skill learning remains less understood. The current study extends the understanding of how load levels affect motor learning by a longitudinal functional near-infrared spectroscopy (fNIRS) study in which 30 participants (15 females) engaged in extensive practice on a two-dimensional continuous hand tracking task with varying task difficulties. We propose the index of difficulty (ID) as a quantitative estimate of task difficulty, which is positively correlated with psychometric measure of subjective workload level. Results shows that as behavioral performance improved over time, participants adopted a direction-specific and load-independent (i.e., consistent across different load levels) control strategy, shifting from feedback-dominant to feedforward-dominant control in the vertical direction as training progressed. Crucially, we provide robust evidence of the learning-induced alteration in load-dependent cortical activation patterns, suggesting that effective motor skill learning may lead to shift towards an inverted-U relationship between activation and load level in the pre-motor and supplementary motor areas. In addition, brain-behavior relationship in the frontoparietal network was strengthened after training. Taken together, our findings provide new insights into the learning-induced plasticity in brain and behavior associated with load-dependent and load-independent contributions to motor skill learning.

neuroscience↗

bioRxiv2023

Neural Deterioration and Compensation in Visual Short-term Memory Among Individuals with Amnestic Mild Cognitive Impairment

Amnestic mild cognitive impairment (aMCI) is considered to carry a high risk of progression to Alzheimers Disease (AD) and it has been characterized by deficits in visual short-term memory (VSTM). However, the relationship between VSTM deficits and pathological brain damage in individuals with MCI has remained unknown. In the current study, we examined a group of 123 elder adults, including 55 with aMCI and 68 age-matched controls. Participants performed color change-detection VSTM tasks, and structural and functional magnetic resonance images were acquired during rest. Compared to the normal control (NC) group, individuals with aMCI exhibited poorer accuracy and longer reaction time in VSTM tasks, along with reduced VSTM capacity. Additionally, structural atrophy was observed in aMCI participants in several brain regions, including the left medial temporal lobe (MTL), the left thalamus, the right frontal pole (FP) and the right postcentral gyrus (postCG). Interestingly, VSTM accuracy and capacity were found to be associated with the volume of the left MTL in the NC group but not in the aMCI group, suggesting alterations in the relationship between VSTM and brain regions in aMCI. However, VSTM capacity was correlated with the volume of the right FP in both groups, suggesting potential compensatory mechanisms involving the prefrontal cortex in aMCI. Moreover, using the atrophic left MTL as a seed, functional connectivity to the right FP was significantly higher in aMCI compared to NC. Notably, this FP area showed overlap with the atrophic frontal areas in terms of structural abnormalities. Furthermore, for individuals with aMCI who had a larger left MTL, the compensatory involvement of the right FP in VSTM, as assessed by brain-behavior correlations, was diminished. In summary, the present study uncovered a mechanism involving MTL dysfunction and prefrontal compensation in aMCI when performing VSTM tasks. These findings may offer valuable insights into potential intervention targets for individuals with aMCI.

pathology↗

bioRxiv2023

Precise Alterations in Hippocampal Neural Deterioration and Neural Correlates of Visual Short-Term Memory in Individuals with Amnestic Mild Cognitive Impairment

PurposeAtrophy of the hippocampus is an early biomarker of Alzheimers disease (AD) and a main contributor to the patients mnemonic degeneration. While previous research has mostly focused on how hippocampal atrophy impaired long-term memory performance, its relation to short-term memory impairment, which was also found among patients with AD, remains largely uninvestigated. Filling this gap, the current study examined how atrophy in the hippocampus and its subfields may have influenced visual short-term memory (VSTM) in patients with amnestic mild cognitive impairment (aMCI), a common precursor of AD. MethodsFifty-eight aMCI patients and 69 healthy controls (HC) matched in age were included in the current study. VSTM was assessed using an adapted change detection task with a memory load of 2 or 4 items. Hippocampal subfields were automatically segmented in T1-weighted image using FreeSurfer and were manually inspected for errors. Volumes of the subfields were extracted and compared between aMCI and HC subjects using ANCOVA with age, gender and education as covariates. Furthermore, we also examined the partial correlation between VSTM performances and hippocampal subfield volumes with age, gender and education as covariates. ResultsCompared to HC subjects, aMCI subjects had lower response accuracy (ACC) and lower memory capacity under both load conditions and had longer reaction time (RT) in the 2-load condition. Left hippocampus volume was significantly smaller in aMCI and was positively correlated with ACC and capacity in HC but not in aMCI. Among the hippocampal subfields, left hippocampal tail, left molecular layer, left dentate gyrus (DG), left CA4, bilateral subiculum, bilateral presubiculum, bilateral fimbria, were significantly smaller while right hippocampal fissure was significantly widened in aMCI compared to HC. Volumes of the left subiculum, left molecular layer, left DG and left CA4 were positively correlated with ACC and capacity in HC but not in aMCI. Bilateral fimbria volume was negatively correlated with RT under the 2-load condition in HC but not in aMCI. ConclusionThe results of this study suggested that hippocampal deterioration, especially in subfields related to information input and output (e.g. molecular layer, DG, subiculum), may have contributed to VSTM impairment in aMCI by disrupting hippocampal-cortical communications. This finding adds to increasing evidence of hippocampal engagement in short-term memory processes and points to VSTM impairment as a potential neuropsychological indicator for MCI and AD.

neuroscience↗

bioRxiv2023

Orthographic deficits but typical visual perceptual processing in Chinese adults with reading disability

Visual orthographic deficits have been reported as one of the core deficits in reading disability (RD), however, whether the deficits are orthographic-specific or domain general in all visual processing is still in debate. Hereby, we conducted an fMRI and an EEG study to examine visual orthographic deficits in Chinese adults with RD. In the fMRI study, we found that there was reduced brain activation in the left inferior temporal gyrus and right cuneus gyrus in orthographic processing (lexical minus perceptual), but not in visual perceptual processing (perceptual minus null) in adults with RD, suggesting orthographic-specific deficits. In the EEG study, adults with RD showed typical visual binding as indicated by intermodulation SSVEPs (steady-state visual-evoked potentials) for both real and pseudo characters, suggesting normal neural phase locking in the visual modality. These results consistently suggest orthographic specific deficits but normal visual perceptual processing in adults with RD, deepening our understanding of the underlying deficits associated with RD.

neuroscience↗

bioRxiv2023

Facial representation comparisons between human brain and deep convolutional neural network reveal a fatigue repetition suppression mechanism

Facial repetition suppression, a well-studied phenomenon characterized by decreased neural responses to repeated faces in visual cortices, remains a subject of ongoing debate regarding its underlying neural mechanisms. Recent advancements have seen deep convolutional neural networks (DCNNs) achieve human-level performance in face recognition. In our present study, we sought to compare brain activation patterns derived from human electroencephalogram (EEG) data with those generated by DCNNs. Employing reverse engineering techniques, we aimed to provide a novel perspective on the neural mechanisms underlying facial repetition suppression. Our approach involved employing brain decoding methods to investigate how representations of faces change with their familiarity in the human brain. Subsequently, we constructed two models for repetition suppression within DCNNs: the Fatigue model, which posits that stronger activation leads to greater suppression, and the Sharpening model, which suggests that weaker activation results in more pronounced suppression. To elucidate the neural mechanisms at play, we conducted cross-modal representational similarity analysis (RSA) comparisons between human EEG signals and DCNN activations. Our results revealed a striking similarity between human brain representations and those of the Fatigue DCNN, favoring the Fatigue model over the Sharpening hypothesis in explaining the facial repetition suppression effect. These representation analyses, bridging the human brain and DCNNs, offer a promising tool for simulating brain activity and making inferences regarding the neural mechanisms underpinning complex human behaviors.

neuroscience↗

bioRxiv2021

Widespread multi-targeted therapy resistance via drug-induced secretome fucosylation

Cancer secretome is a reservoir for aberrant glycosylation. How therapies alter this post-translational cancer hallmark and the consequences thereof remain elusive. Here we show that an elevated secretome fucosylation is a pan-cancer signature of both response and resistance to multiple targeted therapies. Large-scale pharmacogenomics revealed that fucosylation genes display widespread association with resistance to these therapies. In both cancer cell cultures and patients, targeted kinase inhibitors distinctively induced core fucosylation of secreted proteins less than 60 kDa. Label-free proteomics of N-glycoproteomes revealed that fucosylation of the antioxidant PON1 is a critical component of the therapy-induced secretome. Core fucosylation in the Golgi impacts PON1 stability and folding prior to secretion, promoting a more degradation-resistant PON1. Non-specific and PON1-specific secretome de-N-glycosylation both limited the expansion of resistant clones in a tumor regression model. Our findings demonstrate that core fucosylation is a common modification indirectly induced by targeted therapies that paradoxically promotes resistance.

cancer biology↗

bioRxiv2020

Non-canonical immune response to the inhibition of DNA methylation via stabilization of endogenous retrovirus dsRNAs

5-Aza-2'-deoxycytidine, also known as decitabine, is a DNA-methyltransferase inhibitor (DNMTi) used to treat acute myeloid leukemia (AML). Decitabine activates the transcription of endogenous retroviruses (ERV), which can induce an immune response by acting as cellular double-stranded RNAs (dsRNAs). Here, we employ an image-based screening platform to identify dsRNA-binding factors that mediate the downstream effect of ERV induction. We find that Staufen1 (Stau1) knockdown decreases the interferon signature and rescues decitabine-mediated cell death. Moreover, Stau1 directly binds to ERV RNAs and stabilizes them, together with a long non-coding RNA TINCR. We further show that TINCR enhances the interaction between Stau1 and ERV RNAs. Analysis of a clinical patient cohort reveals that AML patients with low Stau1 and TINCR expressions exhibits inferior treatment outcomes to the DNMTi therapy. Our study reveals that decitabine-mediated cell death is a consequence of complex interactions among different dsRNA-binding proteins for access to their common dsRNA targets. HIGHLIHGTSO_LIImage-based RNAi screening reveals multiple dsRBPs regulate response to decitabine C_LIO_LIStau1 binds to ERV RNAs and affects their stability and subcellular localization C_LIO_LITINCR binds to Stau1 and enhances Stau1-ERV interactions C_LIO_LIAML/MDS patients with low Stau1 and TINCR expressions show poor response to DNMTis C_LI

molecular biology↗

bioRxiv2020

Background white noise and speech facilitate visual working memory

In contrast to background white noise, the detrimental effects of background speech on verbal working memory (WM) were often explained by speech interference in the same verbal modality. Yet, those results were confounded with potential differences between arousal levels induced by speech and white noise. To address the role of arousal, in the present study, we minimized the verbal interference and used a visual WM task to test the influence of background speech or white noise. Electrodermal activity (EDA) and Electromyography (EMG) were recorded simultaneously to indicate the arousal levels of participants. Results showed that both background speech and white noise significantly improved visual WM performance. The change of performance further correlated with the change of physiological signals linked with arousal. Taken together, our results suggest that both background speech and white noise facilitate visual WM through raising the arousal level.

physiology↗

bioRxiv2020

NeuroRA: A Python Toolbox of Representational Analysis from Multi-modal Neural Data

In studies of cognitive neuroscience, multivariate pattern analysis (MVPA) is widely used as it offers richer information than traditional univariate analysis. Representational similarity analysis (RSA), as one method of MVPA, has become an effective decoding method based on neural data by calculating the similarity between different representations in the brain under different conditions. Moreover, RSA is suitable for researchers to compare data from different modalities, and even bridge data from different species. However, previous toolboxes have been made to fit for specific datasets. Here, we develop a novel and easy-to-use toolbox based on Python named NeuroRA for representational analysis. Our toolbox aims at conducting cross-modal data analysis from multi-modal neural data (e.g. EEG, MEG, fNIRS, ECoG, sEEG, neuroelectrophysiology, fMRI), behavioral data, and computer simulated data. Compared with previous software packages, our toolbox is more comprehensive and powerful. By using NeuroRA, users can not only calculate the representational dissimilarity matrix (RDM), which reflects the representational similarity between different conditions, but also conduct a representational analysis among different RDMs to achieve a cross-modal comparison. In addition, users can calculate neural pattern similarity, spatiotemporal pattern similarity (STPS) and inter-subject correlation (ISC) with this toolbox. NeuroRA also provides users with functions performing statistical analysis, storage and visualization of results. We introduce the structure, modules, features, and algorithms of NeuroRA in this paper, as well as examples applying the toolbox in published datasets.

neuroscience↗

bioRxiv2019

Reorienting Spatial Attention within Visual Working Memory

Attention and working memory (WM) are intertwined core cognitive processes. Through four experiments with 133 participants, we dissociated the impact of two types of covert spatial attention, endogenous vs. exogenous, on visual WM. Behavioral results consistently indicated that exogenous attentional cues were more advantageous than endogenous ones in enhancing the precision of visual WM under load-2, while they equalized under load-4. In addition, physiological and neural data explained the mechanisms. Converging evidence from eye-tracking, electroencephalography, and magnetoencephalography suggested that fast attentional processing induced by exogenous cues lead to early top-down information from the dorsal lateral prefrontal cortex (DLPFC) to sensory cortices. The differential frontal activities were further correlated with the behavioral distinctions between exogenous and endogenous cues, and transcranial magnetic stimulation over DLPFC at the same time period abolished the exogenous advantage. Taken together, traditionally considered bottom-up attentional processing induced by exogenous cues rapidly engages top-down signals from the frontal cortex, which leads to stronger behavioral benefits compared with the benefits produced by endogenous cues under the low load condition.

neuroscience↗

bioRxiv2019

Unexpected higher resilience to distraction during visual working memory in schizophrenia

Visual working memory (VWM) and distractibility are two core executive functions in human cognition. It has been suggested that schizophrenia (SZ) patients exhibit worse VWM performance and lower resilience to distraction compared with healthy control (HC) subjects. Previous studies, however, have largely investigated these two functions separately. It still remains unclear what are the mechanisms of the deficits, especially the interactions between the two cognitive domains. Here we modify the standard delay-estimation task in VWM and explicitly add distractors in the task so as to examine the two domains simultaneously. We find that SZ indeed exhibit worse performance compared with HC in almost all VWM load and distraction levels, a result consistent with most prior experimental findings. But adding distractors does not selectively impose larger impacts on SZ performance. Furthermore, unlike most previous studies that only focused on behavioral performance, we use the variable precision model to disentangle the distraction effect on different computational components of VWM (resources and resources allocation variability etc.). Surprisingly, adding distractors significantly elevates resources allocation variability--a parameter describing the heterogeneity of resource allocation across different targets--in HC but not in SZ. This counterintuitive result suggests that the internal VWM process in SZ is less interfered by the distractors. However, this unexpected higher resilience to distraction might be associated with less flexible cognitive control mechanisms. In sum, our work demonstrates that multiple cognitive functions might jointly contribute to dysfunctions in SZ and their interactions might manifest differently from merely summing their independent effects.

neuroscience↗

bioRxiv2018

Atypically larger variability of resource allocation accounts for visual working memory deficits in schizophrenia

Schizophrenia patients are known to have profound deficits in visual working memory (VWM), and almost all previous studies attribute the deficits to decreased memory capacity. This account, however, ignores the potential contributions of other VWM components (e.g., memory precision). Here, we measure the VWM performance of schizophrenia patients and healthy control subjects on two classical delay-estimation tasks. Moreover, we thoroughly evaluate several established computational models of VWM to compare the performance of the two groups. We find that the model assuming variable precision across items and trials is the best model to explain the performance of both groups. According to the variable-precision model, schizophrenia subjects exhibit abnormally larger variability of allocating memory resources rather than resources per se. These results invite a rethink of the widely accepted decreased-capacity theory and propose a new perspective on the diagnosis and rehabilitation of schizophrenia.

neuroscience↗

bioRxiv2018

Root Colonization and Growth Promotion of Soybean, Wheat and Chinese Cabbage by Bacillus cereus YL6

Phosphate-solubilizing bacteria (PSB) have been isolated and used in agricultural production. However, comprehensive research on PSB colonizing the rhizosphere of different plants and promoting plant growth is lacking. This study was conducted to study the growth-promoting effects and colonizing capacity of the PSB strain YL6. The YL6 strain not only increased the biomass of pot-planted soybean and wheat but also increased the yield and growth of Chinese cabbage under field conditions. The promotion of growth in these crops by strain YL6 was related to its capacities to dissolve inorganic and organic phosphorus and to produce a certain amount of indole-3-acetic (IAA) and gibberellin (GA). After YL6 was applied to soybean, wheat and Chinese cabbage, the rhizosphere soil available phosphorus (available P) content increased by 120.16%, 62.47% and 7.21%, respectively, and the plant total phosphorus increased by 198.60%, 6.20% and 78.89%, respectively, compared with those of plants without the addition of YL6. To determine whether the phosphate solubilizing bacteria colonized these plants, YL6 labeled with green fluorescent protein (YL6-GFP) was inoculated into plant rhizospheres. YL6-GFP first colonized the root surface and hairs and then penetrated into intercellular spaces and vessels. Collectively, these results demonstrate that YL6 promoted the growth of three different crops and colonized them in a similar way and therefore provide a solid foundation for probing into mechanisms by which phosphate-solubilizing bacteria affect plant growth.

microbiology↗

bioRxiv2018

Neural mechanisms underlying the precision of visual working memory

The neural mechanisms associated with the limited capacity of working memory has long been studied, but it is still unclear how the brain maintains the fidelity of representations in working memory. Here, an orientation recall task for estimating the precision of visual working memory was performed both inside and outside an fMRI scanner. Results showed that the trial-by-trial recall error (in radians) was correlated with delay period activity in the lateral occipital complex (LOC) during working memory maintenance, regardless of the memory load. Moreover, delay activity in LOC also correlated with the individual participants precision of working memory from a separate behavioral experiment held two weeks prior. Furthermore, a region within the prefrontal cortex, the inferior frontal junction (IFJ), exhibited greater functional connectivity with LOC when the working memory load increased. Together, our findings provide unique evidence that the LOC supports visual working memory precision, while communication between the IFJ and LOC varys with visual working memory load.

neuroscience↗

bioRxiv2018

Time-dependent mnemonic vulnerability induced by new-learning

Reactivation renders consolidated memory labile again, and the ensuing temporary reconsolidation process is highly susceptible to mnemonic modification. Here, we show that memories in such an unstable state could be reprogrammed by sheer behavioral means, bypassing the need for pharmacological intervention. In two experiments using a \"face-location associationc\" paradigm in which participants experienced a \"Learning - New-learning - Final-test\" programme, we demonstrate that reactivated memory traces were robustly hampered when the new learning was strategically administered within a critical 20-minute time window. Using fMRI, we further advance our theoretical understanding that this lability can be mechanistically explained by the differential activation in the hippocampal-amygdala memory system implicated by the new-learning whereas the mnemonic intrusion caused by newly learned memories is efficaciously reconciled by the left inferior frontal gyrus. Our findings provide important implications for educational and clinical practices in devising effective strategies for memory integration.

neuroscience↗

bioRxiv2018

Locally distributed abstraction of temporal distance in human parietal cortex

An enduring puzzle in the neuroscience of memory is how the brain parsimoniously situates past events by their order in relation to time. By combining functional MRI, and representational similarity analysis, we reveal a multivoxel representation of time intervals separating pairs of episodic event-moments in the posterior medial memory system, especially when the events were experienced within a similar temporal context. We further show such multivoxel representations to be vulnerable to disruption through targeted repetitive transcranial magnetic stimulation and that perturbation to the mnemonic abstraction alters the neural--behavior relationship across the wider parietal memory network. Our findings establish a mnemonic \"pattern-based\" code of temporal distances in the human brain, a fundamental neural mechanism for supporting the temporal structure of past events, assigning the precuneus as a locus of flexibly effecting the manipulation of physical time during episodic memory retrieval.

neuroscience↗