Frontiers in Human Neuroscience最新文献

Introduction: Pain perception greatly varies among individuals and represents a major clinical challenge. Current pain assessment relies on subjective reports; although straightforward, these cannot distinguish the diverse underlying pathophysiological mechanisms of pain. Elucidating brain functional mechanisms using fMRI is crucial for realizing more objective pain assessment. Most studies have focused on thermal stimuli or psychological evaluations, and no studies have focused on differences in sensitivity to mechanical stimulation. Therefore, in this study, we aimed to identify regional differences in brain activation during mechanical stimulation at different intensities using fMRI and to clarify brain activation patterns associated with differences in pain sensitivity between the low- and high-threshold groups.

Methods: We enrolled 52 healthy adults. After measuring mechanical tactile and pain thresholds, fMRI was performed during mechanical stimulation at three intensities (60, 100, and 180 g). Regions of brain activation were identified for each stimulus intensity in all participants and for the high- and low-threshold groups, using the 100-g stimulus as the cutoff value, based on mechanical pain thresholds.

Results: Notable results regarding the change in stimulus intensity are that significant activation was observed in the anterior insular cortex at 60 g; anterior insular cortex, precentral gyrus, and cerebellum at 100 g; and cerebellum, angular gyrus, and thalamus at 180 g of stimulus intensity. Notable results regarding the level of pain sensitivity are that, when classified into the low- (n = 24) and high-threshold (n = 28) groups, activation in the low-threshold group was limited to the somatosensory cortex and its related regions. However, the high-threshold group exhibited activation in the anterior insular cortex, superior parietal lobule, precentral gyrus, and middle frontal gyrus, in addition to the somatosensory cortex.

Conclusion: The expansion of brain activation with increasing stimulus intensity suggests the involvement of higher-order central processing, such as attention and response preparation, in noxious stimulus processing. Additionally, differences in pain thresholds may reflect variations in the mode of neural response; the high-threshold group exhibited activation in the frontoparietal network, associated with cognitive control. These findings provide a neurobiological basis for psychological interventions and may serve as a foundation for developing objective biomarkers and advancing personalized pain treatment strategies.

Introduction: Transcranial photobiomodulation (tPBM) with near-infrared light is a promising non-invasive method to enhance cognition and support brain health. However, its mechanistic effects on large-scale cortical dynamics remain poorly understood. Establishing how tPBM reorganizes oscillatory hierarchies is critical for advancing both neuroscience and clinical translation.

Methods: We examined whether acute 1,064-nm tPBM modulates oscillatory power, dipole source trajectories, and functional connectivity in the human brain. Simultaneous magnetoencephalography (MEG) and electroencephalography (EEG) were recorded in 25 healthy adults before and after prefrontal tPBM. Distributed source imaging (sLORETA) and global optimization dipole modeling characterized spatiotemporal alpha and beta activity. Connectivity was assessed with phase transfer entropy, and infra-slow phase-amplitude coupling analyses assessed hierarchical modulation.

Results: Transcranial photobiomodulation induced frequency-specific reorganization of cortical networks. Alpha oscillations engaged coordinated fronto-visual circuits, whereas beta activity preferentially recruited higher-order executive regions. Source imaging revealed a post-stimulation shift from default mode toward central executive network dominance with stronger directed interactions. Infra-slow rhythms (<0.1 Hz), encompassing both very-low-frequency (0.01-0.1 Hz) and ultra-slow (<0.01 Hz) activity, significantly modulated alpha- and beta-band amplitudes, embedding faster oscillations within slower temporal patterns.

Discussion: The findings of his work indicate that tPBM influences intrinsic brain activity by reorganizing oscillatory patterns and shifting network engagement. The redistribution from default mode toward executive systems, along with the nesting of faster rhythms within slower temporal structures, reflects a capacity for large-scale functional rebalancing. The results highlight tPBM's potential as a precision neuromodulation tool for modulating executive and cognitive control systems.

Objective: To elucidate the influence of sex differences on the clinical characteristics of anti-NMDAR encephalitis during the acute phase.

Methods: Patients diagnosed with anti-NMDAR encephalitis who were hospitalized at Huanhu Hospital, affiliated with Tianjin University, from January 2020 to January 2025 were collected. They were divided into two groups: male and female. Clinical data for both groups were gathered, including age, history of prodromal infection, clinical manifestations, complications, presence of tumor, laboratory indices, MRI findings, GCS scores, length of hospital stay, treatment regimens, and acute phase outcomes. Statistical methods were employed to compare the differences between the two groups.

Results: A total of 43 patients with anti-NMDAR encephalitis were included in this study, comprising 20 male patients (46.51%) and 23 female patients (53.49%). Female patients were more likely to exhibit decreased levels of consciousness compared to male patients (χ²  = 4.113, p = 0.043). Additionally, the antibody titers in CSF of female patients were significantly higher than those in male patients too (Z = -2.870, p = 0.004). Interestingly, CSF protein levels were higher in male patients than in female patients (Z = -2.591, p = 0.019), and male patients were more prone to test positive for anti-MOG antibodies (χ²  = 5.715, p = 0.017). The treatment improvement rate for female patients was lower than that for male patients (Z = 4.768, p = 0.029), and family members of female patients were more likely to automatic discharge (χ²  = 4.075, p = 0.044).

Conclusion: Female patients with anti-NMDAR encephalitis experience greater challenges and difficulties compared to male patients. Therefore, it is necessary to choose more proactive treatment options for female patients to help reduce the risk of adverse outcome in acute phase.

Introduction: During sensorimotor adaptation, participants respond to a persistent sensory error by shifting behavior to oppose the error. This phenomenon has been measured in multiple motor tasks in which sensory feedback is experimentally altered to artificially introduce an error. Tasks involving multiple cycles of altered and unaltered feedback have been used in the arm reaching domain to understand the mechanisms of un-learning and re-learning a response to an error, but re-learning within a single session has not been studied in the domain of fundamental frequency (f0) control during speech.

Methods: In this study, participants responded to three alternating blocks of f0-shifted and unshifted auditory feedback during a single-word speech task.

Results: It was found that on average, adaptation magnitude decreased in the second and third blocks of shifted feedback compared to the first. This illustrates an attenuation effect similar to that observed in studies of implicit learning in arm reaching tasks.

Discussion: These results support the understanding of f0 control as an implicit learning phenomenon and help place f0 control in the context of motor control in general.

Founders of quantum mechanics (QM) anticipated that revisions to classical physics due to strange elements of quantum reality, would necessitate similar changes in biology. Complexity theory, systems biology and quantum biology provide possible solutions indicating that subject/object separation is a useful fiction for reductive science. Direct correlates to such QM observational/measurement issues as Complementarity and Uncertainty may justify the introduction of an analog of Heisenberg's uncertainty and the Planck constant for living systems. The phase space of "adjacent possibles" for biological systems from which one "actual" is selected resembles the collapse of the QM wave function. Since biological systems are hierarchical, this occurs across organizational scales resulting in biological coherence. The location of a quantum/classical boundary is unclear due to complexity. Whether biological systems' characteristics arise directly from QM or are of a different origin remains unsettled. To combine non-linear with quantum properties across biological scales we propose the Method of Coherent Structures (MCS), developed for quantum many-body systems. In MCS, a higher-level scale provides a classical envelope for quantum fluctuations at the lower scale. It yields a seamless transition from non-linear classical fields to quantum excitations and accounts for the emergence of complexity by incorporating metabolic energy supply.

Introduction: Viewing repetitive striped patterns can induce pattern glare, experienced as visual discomfort (VD). While previous studies examined either pupillary responses or VD separately, few have investigated how they covary or evolve with repeated exposure. This study tested whether pupillary dynamics could serve as potential physiological indicator of individual visual sensitivity beyond subjective reports.

Methods: Across four experiments (preliminary: n = 97; main: n = 70 for spatial frequency, n = 46 for central field size, n = 36 for central blank, with partial overlap), we manipulated spatial frequency, central field size, and surround field size of square-wave gratings (0.5-3 s) while measuring both discomfort and pupil size.

Results: Higher spatial frequencies and larger pattern areas elicited stronger pupillary constriction and greater discomfort, whereas repeated exposures produced cumulative increases in discomfort and decreases in baseline pupil size, consistent with visual strain rather than adaptation. To assess the potential of pupillometry as an indicator of visual discomfort, we examined individual differences in the main spatial-frequency experiment (controlled viewing distance, n = 42). A paradoxical pattern emerged: within participants, stronger stimuli produced greater constriction, but individuals with higher overall discomfort showed weaker constriction and stronger late redilation. Similar dissociations between subjective sensitivity and pupillary responses have been noted in studies of light-induced discomfort, suggesting that related mechanisms may contribute, although their specific physiological basis remains unclear.

Discussion: Overall, our findings clarify how pattern-induced discomfort evolves over time and across individuals and highlight pupillometry's potential as a sensitive, physiological tool for assessing visual sensitivity.

This perspective article explores the transformative potential of brain-Computer Interfaces (BCI) in undergraduate systems engineering programs, a domain characterized by high attrition and a widening gap between rapid technological innovation and slower pedagogical change. I argue that BCI, by enabling real-time detection of cognitive states such as mental workload, attention, and frustration, can evolve from laboratory tools to central pedagogical instruments for adaptive, student-centered education. I review the state-of-the-art methods, which demonstrate the technical feasibility of low-cost electroencephalography (EEG) devices and machine learning algorithms that classify cognitive states with high accuracy in controlled settings. Building on this evidence, I outline concrete applications in three dimensions: formative assessment, dynamic curricular adaptation, and cognitive inclusion, with a specific emphasis on preventing dropout in foundational courses such as algorithms. I also examine ethical, technical, and pedagogical challenges, and propose a scalable, ethically grounded pilot model tailored for universities, particularly in Latin America. This study reports no empirical results. It synthesizes the existing evidence and proposes a roadmap for research and educational action.

Sensory perception relies on the brain's integration of multiple imprecise inputs, a process known as cue combination. Previous research has investigated multisensory integration or unisensory integration within non-haptic senses. In contrast, cue combination within the sense of touch has been understudied. Here, we investigated whether humans optimally combine haptic cutaneous and finger configuration cues when discerning the size of a disk held edge-on between the thumb and index fingers. When these two fingers span the disk to contact its perimeter, a finger configuration cue (the perceived distance between the fingers) provides information about the disk's size. Less obviously, cutaneous cues to disk size may result from the indentation of finger pads caused by the disk's curvature. We considered three hypotheses for how humans might use these cues: they might rely solely on the most reliable cue (Winner-Take-All Model, WTA), combine cues based on a simple arithmetic average (Average Model, AVG), or combine cues via an optimal weighted average (Optimal Model, OPT) in which more reliable cues exert proportionately greater influence on the percept. In three experiments involving 34 participants, we compared participant performance to the predictions of the three models. Each experiment tested participants using a two-interval forced-choice (2IFC) paradigm with 3D printed disk stimuli. On each trial, under occluded vision, participants felt two disks sequentially and responded which felt larger. Participants were tested with the cutaneous index finger cue, cutaneous thumb cue, and finger configuration cue individually and with the three cues together. The three experiments were designed to have progressively greater resolution to distinguish the relevant models from one another. In Experiments 1 and 2, the disks were circular. Experiment 3 included non-circular cue-conflict stimuli. The improvement of accuracy in multi-cue conditions, and perceptual effects of cue-conflict stimuli, were broadly consistent with optimal cue combination. Eight of 12 participants were classified as OPT in Experiment 1; eight of 11 in Experiment 2; and 10 of 11 in Experiment 3. The mean confidence of OPT classifications was 0.56, 0.61, and 0.98, respectively. We conclude that humans combine haptic cues optimally to judge the sizes of held objects.

Background: Forward propulsion during walking is generated by different joints and biomechanical mechanisms depending on environmental and task demands. Although propulsion can be modulated by feedback, it is unclear whether extrinsic and intrinsic feedback generate similar propulsion or promote different joint-level strategies during split-belt walking. The purpose of this study was to investigate strategies used by non-impaired individuals to generate greater propulsion using different feedback to reach targeted levels of propulsion force during split-belt walking.

Methods: Fifteen young adults walked on a split-belt treadmill with the dominant leg on the fast belt at their comfortable walking speed and the non-dominant leg on the slow belt at half speed. They performed trials with extrinsic via visual feedback of propulsive force (targeting 5 and 10% body weight) and with intrinsic feedback via a backward resistive force at the center of mass (5 and 10% body weight). Primary outcome was propulsion accuracy, measured as average propulsion error relative to target levels. Secondary analyses examined explanatory biomechanical variables related to propulsion generation. Outcomes were analyzed using two-way repeated measures ANOVA with Bonferroni correction.

Results: Participants achieved similar target propulsion across feedback types (p = 0.66). However, biomechanical strategies differed. Visual feedback increased trailing limb angle (TLA) at 5% (p = 0.0011) and 10% (p < 0.0001) and increased ankle moment at 5% (p = 0.0005) and 10% (p < 0.0001). In contrast, backward resistive force increased (BRF) hip moment at 5% (p = 0.0018) and 10% (p < 0.0001), and hip power at both 5 and 10% (p < 0.0001). Ankle power did not differ between feedback types at 5% (p = 0.0754) but was greater under BRF at 10% (p < 0.0001).

Conclusion: While both feedback types generate similar propulsion to achieve different target levels during split-belt treadmill walking, they engaged distinct biomechanical strategies. Our results indicate that participants increased TLA and ankle moment under visual feedback. However, they increased hip moment and hip power under BRF, with ankle power adjustments depending on the target level. The findings highlight motor abundance in gait and suggest tailoring rehabilitation strategies in populations with impaired propulsion.