261 research outputs found
TEMPORAL CODING OF SPEECH IN HUMAN AUDITORY CORTEX
Human listeners can reliably recognize speech in complex listening environments. The underlying neural mechanisms, however, remain unclear and cannot yet be emulated by any artificial system. In this dissertation, we study how speech is represented in the human auditory cortex and how the neural representation contributes to reliable speech recognition. Cortical activity from normal hearing human subjects is noninvasively recorded using magnetoencephalography, during natural speech listening. It is first demonstrated that neural activity from auditory cortex is precisely synchronized to the slow temporal modulations of speech, when the speech signal is presented in a quiet listening environment. How this neural representation is affected by acoustic interference is then investigated. Acoustic interference degrades speech perception via two mechanisms, informational masking and energetic masking, which are addressed respectively by using a competing speech stream and a stationary noise as the interfering sound. When two speech streams are presented simultaneously, cortical activity is predominantly synchronized to the speech stream the listener attends to, even if the unattended, competing speech stream is 8 dB more intense. When speech is presented together with spectrally matched stationary noise, cortical activity remains precisely synchronized to the temporal modulations of speech until the noise is 9 dB more intense. Critically, the accuracy of neural synchronization to speech predicts how well individual listeners can understand speech in noise.
Further analysis reveals that two neural sources contribute to speech synchronized cortical activity, one with a shorter response latency of about 50 ms and the other with a longer response latency of about 100 ms. The longer-latency component, but not the shorter-latency component, shows selectivity to the attended speech and invariance to background noise, indicating a transition from encoding the acoustic scene to encoding the behaviorally important auditory object, in auditory cortex. Taken together, we have demonstrated that during natural speech comprehension, neural activity in the human auditory cortex is precisely synchronized to the slow temporal modulations of speech. This neural synchronization is robust to acoustic interference, whether speech or noise, and therefore provides a strong candidate for the neural basis of acoustic background invariant speech recognition
Deep Neural Networks Evolve Human-like Attention Distribution during Reading Comprehension
Attention is a key mechanism for information selection in both biological
brains and many state-of-the-art deep neural networks (DNNs). Here, we
investigate whether humans and DNNs allocate attention in comparable ways when
reading a text passage to subsequently answer a specific question. We analyze 3
transformer-based DNNs that reach human-level performance when trained to
perform the reading comprehension task. We find that the DNN attention
distribution quantitatively resembles human attention distribution measured by
fixation times. Human readers fixate longer on words that are more relevant to
the question-answering task, demonstrating that attention is modulated by
top-down reading goals, on top of lower-level visual and text features of the
stimulus. Further analyses reveal that the attention weights in DNNs are also
influenced by both top-down reading goals and lower-level stimulus features,
with the shallow layers more strongly influenced by lower-level text features
and the deep layers attending more to task-relevant words. Additionally, deep
layers' attention to task-relevant words gradually emerges when pre-trained DNN
models are fine-tuned to perform the reading comprehension task, which
coincides with the improvement in task performance. These results demonstrate
that DNNs can evolve human-like attention distribution through task
optimization, which suggests that human attention during goal-directed reading
comprehension is a consequence of task optimization
Characterizing Neural Entrainment to Hierarchical Linguistic Units using Electroencephalography (EEG)
To understand speech, listeners have to combine the words they hear into phrases and sentences. Recent magnetoencephalography (MEG) and electrocorticography (ECoG) studies show that cortical activity is concurrently entrained/synchronized to the rhythms of multiple levels of linguistic units including words, phrases, and sentences. Here we investigate whether this phenomenon can be observed using electroencephalography (EEG), a technique that is more widely available than MEG and ECoG. We show that the EEG responses concurrently track the rhythms of hierarchical linguistic units such as syllables/words, phrases, and sentences. The strength of the sentential-rate response correlates with how well each subject can detect random words embedded in a sequence of sentences. In contrast, only a syllabic-rate response is observed for an unintelligible control stimulus. In sum, EEG provides a useful tool to characterize neural encoding of hierarchical linguistic units, potentially even in individual participants
Research on Intellectual Capital Business Model in China: A Case Study in K Group
Focus on the practice of intellectual capital business model (ICBM) in high technology enterprises in China would be very important to the development of Chinese economic reform. The case study of K Group shows that we should examine the intellectual property right (IPR) protection system from three-dimensional perspective constituting law, economics and management to fully understand the ICBM. Policy recommendations following for the analysis can then help Chinese high technology enterprises strengthen their international competitiveness and raise their IPR protection level higher in the future
Differences in Neurocognitive Mechanisms Underlying the Processing of Center-Embedded and Non–embedded Musical Structures
In music, chords are organized into hierarchical structures based on recursive or embedded syntax. How the brain extracts recursive grammar is a central question in musical cognition and other cognitive neuroscience, but the precise mechanism remains unclear. By analyzing event related potentials (ERPs) and neural oscillatory activity, the present study investigated neurocognitive mechanisms underlying the processing of center-embedded structure in music by examining the differences in center-embedded and non-embedded structure processing and evaluating how these differences are affected by musical proficiency. Based on Western musical proficiency, the subjects were divided into two groups, non-experts and experts. The results revealed that for non-experts, the processing of center-embedded structure elicited greater early right-anterior negativity (ERAN) and N5 components as well as, reduced alpha and gamma activities than did the non-embedded structure. For experts, no significant difference in the ERP response was observed between the processing of non-embedded and center-embedded structures; however, the processing of center-embedded structure elicited increased beta activity compared to non-embedded structure. These findings indicate that listeners different in proficiency would rely on different cognitive neural mechanisms in music processing with the syntactic complexity increases
CTP:A Causal Interpretable Model for Non-Communicable Disease Progression Prediction
Non-communicable disease is the leading cause of death, emphasizing the need
for accurate prediction of disease progression and informed clinical
decision-making. Machine learning (ML) models have shown promise in this domain
by capturing non-linear patterns within patient features. However, existing
ML-based models cannot provide causal interpretable predictions and estimate
treatment effects, limiting their decision-making perspective. In this study,
we propose a novel model called causal trajectory prediction (CTP) to tackle
the limitation. The CTP model combines trajectory prediction and causal
discovery to enable accurate prediction of disease progression trajectories and
uncover causal relationships between features. By incorporating a causal graph
into the prediction process, CTP ensures that ancestor features are not
influenced by the treatment of descendant features, thereby enhancing the
interpretability of the model. By estimating the bounds of treatment effects,
even in the presence of unmeasured confounders, the CTP provides valuable
insights for clinical decision-making. We evaluate the performance of the CTP
using simulated and real medical datasets. Experimental results demonstrate
that our model achieves satisfactory performance, highlighting its potential to
assist clinical decisions. Source code is in
\href{https://github.com/DanielSun94/CFPA}{here}.Comment: 25 pages, 5 figures, 12 table
Holistic Dynamic Frequency Transformer for Image Fusion and Exposure Correction
The correction of exposure-related issues is a pivotal component in enhancing
the quality of images, offering substantial implications for various computer
vision tasks. Historically, most methodologies have predominantly utilized
spatial domain recovery, offering limited consideration to the potentialities
of the frequency domain. Additionally, there has been a lack of a unified
perspective towards low-light enhancement, exposure correction, and
multi-exposure fusion, complicating and impeding the optimization of image
processing. In response to these challenges, this paper proposes a novel
methodology that leverages the frequency domain to improve and unify the
handling of exposure correction tasks. Our method introduces Holistic Frequency
Attention and Dynamic Frequency Feed-Forward Network, which replace
conventional correlation computation in the spatial-domain. They form a
foundational building block that facilitates a U-shaped Holistic Dynamic
Frequency Transformer as a filter to extract global information and dynamically
select important frequency bands for image restoration. Complementing this, we
employ a Laplacian pyramid to decompose images into distinct frequency bands,
followed by multiple restorers, each tuned to recover specific frequency-band
information. The pyramid fusion allows a more detailed and nuanced image
restoration process. Ultimately, our structure unifies the three tasks of
low-light enhancement, exposure correction, and multi-exposure fusion, enabling
comprehensive treatment of all classical exposure errors. Benchmarking on
mainstream datasets for these tasks, our proposed method achieves
state-of-the-art results, paving the way for more sophisticated and unified
solutions in exposure correction
Abiotic Stresses: General Defenses of Land Plants and Chances for Engineering Multistress Tolerance
Abiotic stresses, such as low or high temperature, deficient or excessive water, high salinity, heavy metals, and ultraviolet radiation, are hostile to plant growth and development, leading to great crop yield penalty worldwide. It is getting imperative to equip crops with multistress tolerance to relieve the pressure of environmental changes and to meet the demand of population growth, as different abiotic stresses usually arise together in the field. The feasibility is raised as land plants actually have established more generalized defenses against abiotic stresses, including the cuticle outside plants, together with unsaturated fatty acids, reactive species scavengers, molecular chaperones, and compatible solutes inside cells. In stress response, they are orchestrated by a complex regulatory network involving upstream signaling molecules including stress hormones, reactive oxygen species, gasotransmitters, polyamines, phytochromes, and calcium, as well as downstream gene regulation factors, particularly transcription factors. In this review, we aimed at presenting an overview of these defensive systems and the regulatory network, with an eye to their practical potential via genetic engineering and/or exogenous application
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