Frontiers in Human Neuroscience最新文献

Objective: This study aims to establish the risk factors and predictive model for the occurrence of delayed hyponatremia after endoscopic endonasal transsphenoidal resection of pituitary adenoma.

Methods: Data from 155 patients who underwent endoscopic endonasal transsphenoidal resection of pituitary adenoma at the affiliated hospital of Xuzhou Medical University from January 2018 to May 2023 were analyzed. These patients were randomly divided into a training group (108 cases, 70%) and a validation group (47 cases, 30%). Univariate and Multivariate Logistic regression analysis were conducted on the training group to identify risk factors for delayed hyponatremia after surgery. A predictive model was established using R software and validated.

Results: After conducting Univariate and Multivariate Logistic regression analysis, factors influencing the occurrence of delayed hyponatremia after endoscopic endonasal transsphenoidal resection of pituitary adenoma were identified as follows: elevated preoperative prolactin levels, higher preoperative suprasellar cistern height, and hyponatremia in the first 1-2 days after surgery. The area under the ROC curve for forecasting delayed postoperative hyponatremia (DPH) in training and validation sets was 0.943 and 0.959, respectively. The DCA curve indicated a higher benefit in clinical application.

Conclusion: The risk prediction model for delayed hyponatremia after endoscopic endonasal transsphenoidal resection of pituitary adenoma, developed in this study, demonstrates favorable predictive performance. The nomogram can be utilized for early identification of high-risk individuals for DPH.

Lexical retrieval is commonly impaired in many persons with aphasia (PWA). Verbal fluency tasks are often used to assess lexical retrieval ability. However, common methods of analyzing verbal fluency data (e.g., total number of appropriate responses, clustering and switching) fail to adequately capture the underlying organization of the mental lexicon. To better understand the nature of lexical-semantic organization in aphasia, this study applied a semantic network approach to verbal fluency data obtained from 120 healthy controls and 127 PWA (64 fluent and 63 nonfluent). Participants named as many animal category members as they could in 1 min, and their responses were converted into semantic networks. Global network metrics were computed for each group, including average shortest path length, clustering coefficient, and modularity. Compared to the healthy control network, the PWA network was less integrated and more fragmented, reflected by longer average shortest path lengths, reduced clustering, and higher modularity. These disruptions were especially evident in the nonfluent PWA network compared to the fluent PWA network. Complementary spreading activation and percolation analyses demonstrated that PWA networks were both less efficient and less resilient to disruption. Our results demonstrate that network-based analyses of verbal fluency provide a sensitive measure of lexical-semantic organization in aphasia, revealing structural disruptions that are not fully captured by traditional analyses. More broadly, this approach highlights how network science can advance theories of lexical-semantic organization and inform the development of individualized clinical assessments and treatment strategies.

Background: High-definition transcranial direct current stimulation (HD-tDCS) is a non-invasive brain stimulation technique that offers increased spatial precision compared to conventional tDCS. As its use has expanded across research and clinical settings, there has been increasing interest in understanding its safety and tolerability.

Objective: This review summarizes adverse events related to HD-tDCS in both healthy and clinical populations, focusing on how stimulation intensity, session frequency, and polarity influence tolerability.

Results: In healthy populations, HD-tDCS is most often administered at 1-2 mA for 20 min. The most reported adverse events include tingling, itching and burning localized to the site of stimulation, typically described as mild or transient. Studies comparing active and sham stimulation generally report no significant differences in adverse event frequency or intensity, even at higher intensities of 2-3 mA. Reports of severe adverse events are rare, and participant dropout due to discomfort is uncommon. Multi-session protocols show similar safety profiles, suggesting that repeated stimulation does not increase adverse effects. In clinical populations HD-tDCS is typically delivered across multiple sessions. Reported adverse events are mild and transient, with few reports of severe outcomes. Polarity-specific comparisons suggest that anodal and cathodal stimulation are similarly tolerated, with no notable differences in adverse event profiles.

Conclusion: Overall, current evidence indicates that HD-tDCS is a safe and well-tolerated technique across diverse populations and stimulation parameters. Continued use of standardized adverse event reporting will be important to further confirm these findings as clinical application broaden.

Background: There is a lack of objective evaluation tools for assessing upper limb motor dysfunction in ischemic stroke patients (ULMD-IS). This study aimed to develop and validate a diagnostic nomogram for diagnosing the severity of ULMD-IS using functional near-infrared spectroscopy (fNIRS) data.

Methods: This retrospective analysis included 275 ULMD-IS patients at Tianjin Medical University General Hospital. Patients were randomly assigned to a training group (n = 193) or a validation group (n = 82). The data were preprocessed using HOMER2. In the training group, least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression were employed to identify predictive variables and construct the nomogram. The nomogram's performance was validated using the area under the receiver operating characteristic curve (AUC), the Hosmer-Lemeshow goodness-of-fit test, calibration curves, and decision curve analysis (DCA).

Results: No significant differences in baseline characteristics, including sex, age, lesion hemisphere, or medical history, were observed between the training and validation groups. LASSO regression analysis identified three independent risk factors: deoxyhemoglobin (HbD) levels in the affected temporal region, total hemoglobin (HbT) levels in the total region, and HbT levels in the unaffected frontopolar region. These factors showed good differentiation ability (training group AUC: 0.766, verification group AUC: 0.861). The model's goodness-of-fit was confirmed, and it demonstrated a favorable net clinical benefit. Additionally, correlation analysis between these model variables and activities of daily living (ADL) scores revealed no significant relationships (p > 0.05 for all variables), indicating that the identified risk factors may not directly influence ADL performance.

Conclusion: This study identified HbD in the affected temporal region, Total HbT levels, and HbT in the unaffected frontopolar region as independent risk factors for diagnosing the severity of ULMD-IS, and a corresponding predictive model was constructed. Given the model's limited sensitivity, the nomogram should be regarded only as a supplementary reference for objectively assessing post-stroke motor dysfunction; its utility in predicting treatment outcomes and guiding therapeutic choices remains modest and warrants cautious interpretation.

Introduction: Supplementary motor area (SMA) hyperactivity is thought to be a key neural mechanism in tics. This study probed SMA's role in tic expression, voluntary tic control, and premonitory urge experiences using one session of 1 Hz "inhibitory" repetitive transcranial magnetic stimulation (rTMS) targeting SMA in a repeated measures, small-N experimental design.

Methods: Youth with Tourette Syndrome (TS) ages 12-17 years (N = 14) completed a clinical assessment and MRI to localize SMA. The video-based Tic Suppression Task (TST) quantified tic frequency and urges during conditions of Free-to-Tic, Suppression, and Suppression+Reward. The TST was followed by randomly assigned active 1 Hz (n = 8) or sham rTMS (n = 6) and TST repetition post-stimulation.

Results: Active rTMS led to greater tic frequency reductions during Free-to-Tic (d = 0.34) and Suppression+Reward (d = 0.24) but not Suppression (d = 0.0). A stronger effect size for active rTMS was observed in both suppression conditions (d = 0.26, d = 0.63) when excluding participants classified as baseline "strong suppressors" (n = 5). Urges did not differ group-wise for Free-to-Tic (d = 0.09) but decreased more following active rTMS in both suppression conditions (d = 0.19, d = 0.52).

Discussion: Overall, results suggest that the acute aftereffects of active 1 Hz rTMS to SMA may include reduced natural tic frequency, improved tic controllability, and lower urge intensity, especially while engaged in suppression efforts. Results are consistent with prior literature pointing to SMA hyperactivation in TS and suggests the potential therapeutic value of rTMS.

Empirical findings indicate that conscious states are inextricably linked to long-range synchronized activity patterns that result from phase transitions and exhibit the key features of self-organized criticality. This article builds a bridge between these neurophysiological characteristics of consciousness and the framework of quantum electrodynamics (QED), which provides the appropriate methodological resources for explaining the origin of phase transitions and critical dynamics. An essential ingredient of QED is a fluctuating ocean of energy, the ubiquitous electromagnetic zero-point field (ZPF), consisting of a spectrum of normal modes. It can be deduced from QED-based model calculations that the resonant interaction of the ZPF with the glutamate pool of cortical microcolumns is an important prerequisite for the initiation of phase transitions, giving rise to macroscopic quantum effects that play a crucial role in modulating the activity of ion channels and regulating the neuronal firing rate. The firing rate of pyramidal neurons and inhibitory interneurons determines the excitatory-inhibitory balance, which has been identified as the essential control parameter for establishing and maintaining the critical regime. Thus, taking all available pieces of evidence into account, profound new insights take shape, namely, that self-organized criticality arises from a bottom-up orchestration process involving the ZPF and that the fundamental principle behind the formation of conscious states is the resonant coupling of the brain to the ZPF. This coupling causes an amplification of the dynamically relevant ZPF modes, suggesting that the ZPF holds the key to the understanding of consciousness and that the necessary condition for the formation of a conscious state is the selective excitation of ZPF modes. These insights pave the way for novel experimental paradigms designed to systematically manipulate conditions in the brain, thereby collecting new data that can be used to empirically substantiate the significance of resonant brain-ZPF interaction for the formation of conscious states.

Introduction: Dysphagia, or difficulty swallowing, is common after stroke and can lead to complications like malnutrition, aspiration pneumonia, and increased mortality. Recovery is driven by neural reorganization, yet traditional interventions focus on managing swallowing difficulties rather than restoring brain function. Neuromodulatory approaches like repetitive transcranial magnetic stimulation (rTMS) show potential for promoting brain plasticity and recovery. While rTMS has demonstrated efficacy in improving swallowing after stroke, few studies have explored its neural mechanisms at the brain level, as opposed to focusing on motor-evoked potentials recorded from peripheral muscles.

Methods: This study examined the effects of 5 Hz rTMS on post-stroke dysphagia by targeting the contralesional mylohyoid cortical area. Resting-state fMRI was employed to investigate the neural correlates of rTMS effects. Local brain activity was measured using the amplitude of low-frequency fluctuation (ALFF), fractional amplitude of low-frequency fluctuation (fALFF), and percentage amplitude of fluctuation (PerAF), while network connectivity was assessed with graph theory analysis.

Results: rTMS reduced spontaneous activity in the contralesional middle frontal gyrus and putamen, and in the ipsilesional insula and middle frontal gyrus (pars orbitalis), regions that were hyperactive at baseline in dysphagic patients. Altered network topology in the left medial superior frontal gyrus suggested connectivity reorganization.

Conclusion: These preliminary findings support rTMS as a promising adjunct therapy for post-stroke dysphagia by inducing cortical plasticity, as demonstrated by changes in both regional activity and network topology. Further validation in studies with larger samples is needed.

Objective: This study aimed to investigate the eye movement behavior characteristics and associated brain functional activity changes in Parkinson's disease (PD) patients during a complex visual task, using virtual reality (VR) eye movement tasks combined with functional near-infrared spectroscopy (fNIRS) technology.

Methods: A total of 27 PD patients and 29 healthy controls were included in the study. Participants performed a "Whack-a-Mole" eye movement task on a VR platform. Fixation time and task error rates were recorded, and fNIRS was used to measure changes in brain oxygenation. The differences in oxygenated hemoglobin concentration in brain regions between PD patients and healthy controls were assessed during task performance.

Results: The PD group exhibited a significantly higher task error rate compared to the control group (p = 0.02), and a significantly longer mean fixation time (p = 0.001). fNIRS results revealed that the PD group had considerably higher oxygenated hemoglobin concentrations in the bilateral primary visual cortex (V1), visual association cortex, primary somatosensory cortex (S1), and auditory cortex compared to the control group (p < 0.05).

Conclusion: PD patients exhibit significant eye movement behavioral impairments during the execution of complex visual tasks, accompanied by compensatory brain functional activation in relevant brain regions. These findings provide important insights for the early diagnosis and therapeutic intervention of PD.

Introduction: Difficulties in direct visualization of thalamic subnuclei are likely a contributor to inconsistent surgical outcomes among patients with medication refractory tremors. We present a new MRI landmark, represented by a bright signal in the posterior limb of the internal capsule signal (PICS), that can serve as a consistent marker for indirect location of the Vim nucleus of the thalamus. We evaluated the visibility of PICS across multiple MRI sequences at 7Tesla (T) and 3T, and its anatomical characteristics were identified using tractography.

Methods: One healthy control and 15 essential tremor (ET) patients were scanned. To characterize the PICS fibers, two posterior limb of internal capsule (pLIC) tractography schemes were conducted with cortical ROIs as seeds and the pLIC as a waypoint: (i) gross motor cortical ROIs, (ii) M1 and S1 homunculus. Finally, intra- and post-operative clinical data were merged for one ET DBS patient to show correspondence between the parcellation results and clinical observations.

Results: PICS was consistently identified across multiple MRI sequences. Tractography analyses identified PICS to correlate with the distribution of motor fibers from the internal capsule. For the M1 homunculus, two somatotopic clusters were observed: one including mostly trunk, lower and upper limbs; and another, more anteriorly, with head/face clustering with tongue/larynx. For the S1 homunculus, the trunk region was overall the most posterior region followed by the upper limb/face anteriorly and Area2. Intra-operative stimulation at two different depths resulted in pLIC-specific side effect in the tongue/face. At those depths, measurements showed closer proximity of the DBS electrode to M1 clusters of head/face and tongue/larynx, validating the imaging findings.

Conclusion: PICS appears to be a reliable radiological marker comprising cortico-spinal tracts, in isolation from corticobulbar tracts fibers. It is consistently located lateral to the Vim, making it a potential landmark to infer Vim location and help refine targeting for thalamic procedures. The parcellations of the pLIC using M1 homunculus could potentially inform lead or ablation location based on side effect profiles (e.g., head/face/tongue vs. trunk/limbs). Therefore, proximity or distance to PICS may potentially guide lead placement to avoid procedure-related capsular side effects while optimizing benefits.

Human olfactory perception and naming represent a complex example of multisensory integration, with growing interest in how cues from different modalities affect olfactory recognition and naming. While studies show that visual cues may support odor naming performance, little is known about how cueing and multisensory integration in odor naming tasks influence neural mechanisms. This study examined the cognitive mechanisms underlying odor identification and the effect of two visual cue types-lexical and color-using behavioral and EEG methods. It also investigated the impact of hedonic ratings, Tip of the Nose phenomenon, familiarity, and subjective recall experiences on odor naming. Forty participants took part in an odor identification task using Sniffin' Sticks. For each trial, an odorant was first presented, followed by either a visual cue (a color patch associated with the odor source) or a lexical cue (a word fragment). Participants were then asked to name the odor. To examine the neural mechanisms involved in cue-assisted odor identification, the time window during odor naming after the visual cue presentation was analyzed. Connectivity analysis and behavioral performance were assessed to evaluate the effectiveness of the different cue types in supporting identification. Behavioral findings showed that lexical cues improved identification accuracy. Furthermore, hedonic ratings, familiarity, and experiences related to the TON were found to significantly affect naming performance. Odor familiarity and liking levels affected both response accuracy and response time, with more familiar and liked odors being identified both more accurately and more quickly. Granger causality analysis revealed that the color cue condition exhibited more numerous and stronger network connections compared to the lexical cue condition. The lexical cue condition demonstrated more restricted network activation with fewer connections, utilizing focused frontal-temporal and frontal-parietal circuits. In both conditions, prefrontal regions served as strong control hubs, and language networks were preserved. However, additional frontal-occipital connections were observed in the color cue condition, in the form of interhemispheric coordination and visual system integration. The findings demonstrated that cross-modal odor naming utilizes different neural connections depending on cue type, with lexical cues showing more direct access to linguistic areas while color cues exhibit more complex connectivity patterns.