Abstract
Brain network dynamics not only endow the brain with flexible coordination for various cognitive processes but also with a huge potential of neuroplasticity for development, skill learning, ...and after cerebral injury. Diffusive and progressive glioma infiltration triggers the neuroplasticity for functional compensation, which is an outstanding pathophysiological model for the investigation of network reorganization underlying neuroplasticity. In this study, we employed dynamic conditional correlation to construct framewise language networks and investigated dynamic reorganizations in 83 patients with left hemispheric gliomas involving language networks (40 patients without aphasia and 43 patients with aphasia). We found that, in healthy controls (HCs) and patients, the language network dynamics in resting state clustered into 4 temporal-reoccurring states. Language deficits-severity-dependent topological abnormalities of dFCs were observed. Compared with HCs, suboptimal language network dynamics were observed for those patients without aphasia, while more severe network disruptions were observed for those patients with aphasia. Machine learning-based dFC-linguistics prediction analyses showed that dFCs of the 4 states significantly predicted individual patients’ language scores. These findings shed light on our understanding of metaplasticity in glioma.
Glioma-induced language network reorganizations were investigated under a dynamic “meta-networking” (network of networks) framework.
In healthy controls and patients with glioma, the framewise language network dynamics in resting-state robustly clustered into 4 temporal-reoccurring states.
The spatial but not temporal language deficits-severity-dependent abnormalities of dFCs were observed in patients with left hemispheric gliomas involving language network.
Language network dynamics significantly predicted individual patients’ language scores.
In the mammalian brain, sensory cortices exhibit plasticity during task learning, but how this alters information transferred between connected cortical areas remains unknown. We found that divergent ...subpopulations of cortico-cortical neurons in mouse whisker primary somatosensory cortex (S1) undergo functional changes reflecting learned behavior. We chronically imaged activity of S1 neurons projecting to secondary somatosensory (S2) or primary motor (M1) cortex in mice learning a texture discrimination task. Mice adopted an active whisking strategy that enhanced texture-related whisker kinematics, correlating with task performance. M1-projecting neurons reliably encoded basic kinematics features, and an additional subset of touch-related neurons was recruited that persisted past training. The number of S2-projecting touch neurons remained constant, but improved their discrimination of trial types through reorganization while developing activity patterns capable of discriminating the animal's decision. We propose that learning-related changes in S1 enhance sensory representations in a pathway-specific manner, providing downstream areas with task-relevant information for behavior.
Major depressive disorder (MDD) affects millions of people worldwide and is a leading cause of disability. Several theories have been proposed to explain its pathological mechanisms, and the ..."neurotrophin hypothesis of depression" involves one of the most relevant pathways. Brain-derived neurotrophic factor (BDNF) is an important neurotrophin, and it has been extensively investigated in both experimental models and clinical studies of MDD. Robust empirical findings have indicated an association between increased BDNF gene expression and peripheral concentration with improved neuronal plasticity and neurogenesis. Additionally, several studies have indicated the blunt expression of BDNF in carriers of the Val66Met gene polymorphism and lower blood BDNF (serum or plasma) levels in depressed individuals. Clinical trials have yielded mixed results with different treatment options, peripheral blood BDNF measurement techniques, and time of observation. Previous meta-analyses of MDD treatment have indicated that antidepressants and electroconvulsive therapy showed higher levels of blood BDNF after treatment but not with physical exercise, psychotherapy, or direct current stimulation. Moreover, the rapid-acting antidepressant ketamine has presented an early increase in blood BDNF concentration. Although evidence has pointed to increased levels of BDNF after antidepressant therapy, several factors, such as heterogeneous results, low sample size, publication bias, and different BDNF measurements (serum or plasma), pose a challenge in the interpretation of the relation between peripheral blood BDNF and MDD. These potential gaps in the literature have not been properly addressed in previous narrative reviews. In this review, current evidence regarding BDNF function, genetics and epigenetics, expression, and results from clinical trials is summarized, putting the literature into a translational perspective on MDD. In general, blood BDNF cannot be recommended for use as a biomarker in clinical practice. Moreover, future studies should expand the evidence with larger samples, use the serum or serum: whole blood concentration of BDNF as a more accurate measure of peripheral BDNF, and compare its change upon different treatment modalities of MDD.
Perceptual training has been argued to be a potential means to modify temporal sensitivity (the ability to detect a time-based discrepancy between two stimuli) with previous studies providing ...preliminary evidence that perceptual training can lead to increased temporal sensitivity. However, previous studies have not employed a control group and therefore cannot rule out the possibility that the observed effects are due to repeated completion of the task, rather than the training itself. Moreover, despite temporal sensitivity being suggested to be an important aspect of the sense of agency, the effects of perceptual training on the sense of agency have not been explored. Therefore, this study aimed to explore the effects of perceptual training on the sense of agency and replicate previously observed effects on temporal sensitivity while utilizing a more rigorous methodology. Given the existing literature, it was predicted that the sense of agency and temporal sensitivity will be enhanced following perceptual training. Temporal sensitivity was only weakly modified by perceptual training when compared to the control condition. Sense of agency was significantly modulated by perceptual training, over and above the control condition. This study's findings present novel evidence indicating that perceptual training can influence high-level processes such as the sense of agency and temporal sensitivity.
Evidence from preclinical and clinical research suggest that neuromodulation technologies can facilitate the sublesional spinal networks, isolated from supraspinal commands after spinal cord injury ...(SCI), by reestablishing the levels of excitability and enabling descending motor signals via residual connections. Herein, we evaluate available evidence that sublesional and supralesional spinal circuits could form a translesional spinal network after SCI. We further discuss evidence of translesional network reorganization after SCI in the presence of sensory inputs during motor training. In this review, we evaluate potential mechanisms that underlie translesional circuitry reorganization during neuromodulation and rehabilitation in order to enable motor functions after SCI. We discuss the potential of neuromodulation technologies to engage various components that comprise the translesional network, their functional recovery after SCI, and the implications of the concept of translesional network in development of future neuromodulation, rehabilitation, and neuroprosthetics technologies.
This systematic review aimed to evaluate the effects of different theta burst stimulation (TBS) protocols on improving upper extremity motor functions in patients with stroke, their associated ...modulators of efficacy, and the underlying neural mechanisms. We conducted a meta-analytic review of 29 controlled trials published from January 1, 2000, to August 29, 2023, which investigated the effects of TBS on upper extremity motor, neurophysiological, and neuroimaging outcomes in poststroke patients. TBS significantly improved upper extremity motor impairment (Hedge's
= 0.646,
= 0.003) and functional activity (Hedge's
= 0.500,
< 0.001) compared to controls. Meta-regression revealed a significant relationship between the percentage of patients with subcortical stroke and the effect sizes of motor impairment (
= 0.015) and functional activity (
= 0.018). Subgroup analysis revealed a significant difference in the improvement of upper extremity motor impairment between studies using 600-pulse and 1200-pulse TBS (
= 0.002). Neurophysiological studies have consistently found that intermittent TBS increases ipsilesional corticomotor excitability. However, evidence to support the regional effects of continuous TBS, as well as the remote and network effects of TBS, is still mixed and relatively insufficient. In conclusion, TBS is effective in enhancing poststroke upper extremity motor function. Patients with preserved cortices may respond better to TBS. Novel TBS protocols with a higher dose may lead to superior efficacy compared with the conventional 600-pulse protocol. The mechanisms of poststroke recovery facilitated by TBS can be primarily attributed to the modulation of corticomotor excitability and is possibly caused by the recruitment of corticomotor networks connected to the ipsilesional motor cortex.
Multisensory awareness of one’s own body relies on the integration of signals from various sensory modalities such as vision, touch, and proprioception. But how do blind individuals perceive their ...bodies without visual cues, and does the brain of a blind person integrate bodily senses differently from a sighted person? To address this question, we aimed to replicate the only two previous studies on this topic, which claimed that blind individuals do not experience the somatic rubber hand illusion, a bodily illusion triggered by the integration of correlated tactile and proprioceptive signals from the two hands. We used a larger sample size than the previous studies and added Bayesian analyses to examine statistical evidence in favor of the lack of an illusion effect. Moreover, we employed tests to investigate whether enhanced tactile acuity and cardiac interoceptive accuracy in blind individuals could also explain the weaker illusion. We tested 36 blind individuals and 36 age- and sex-matched sighted volunteers. The results show that blind individuals do not experience the somatic rubber hand illusion based on questionnaire ratings and behavioral measures that assessed changes in hand position sense toward the location of the rubber hand. This conclusion is supported by Bayesian evidence in favor of the null hypothesis. The findings confirm that blind individuals do not experience the somatic rubber hand illusion, indicating that lack of visual experience leads to permanent changes in multisensory bodily perception. In summary, our study suggests that changes in multisensory integration of tactile and proprioceptive signals may explain why blind individuals are “immune” to the nonvisual version of the rubber hand illusion.
Mild cognitive impairment is an age-related cognitive disorder which is associated with frequent memory lapses, impaired judgement, and progressive functional decline. If untreated early, 39.2% of ...people with mild cognitive impairment could progress to develop dementia. However, there are currently no approved pharmacological interventions to treat the condition, which lead researchers to explore non-pharmacological options, such as dance therapy.
This systematic review aimed to examine the effectiveness of dance interventions on cognition, neuroplasticity, physical function, depression, and quality of life in older adults with mild cognitive impairment.
Seven databases were systematically searched from their respective inception dates to 31 March 2020. Relevant randomized controlled trials (RCTs) were screened and assessed for risk of bias. Eight RCTs evaluating dance interventions were included.
Results showed that dance interventions had a significant moderate effect on global cognition (SMD=0.54, Z = 3.55, p<0.001), significantly improved memory (SMD=0.33, Z = 3.97, p<0.001), visuospatial function (SMD=0.42, Z = 2.41, p = 0.02), and language (SMD=0.39, Z = 2.69, p = 0.007). We found that dance interventions produced a significant moderate effect on physical function (SMD=0.55, Z = 3.43, p<0.001), and a significant effect on quality of life (SMD=0.93, Z = 5.04, p<0.0.001).
Dance is a non-pharmacological and inexpensive intervention that can be implemented for older adults on a large scale. It can slow down the cognitive deterioration of older adults with mild cognitive impairment. However, the findings should be interpreted with caution due to the heterogeneity in intervention designs. Rigorous design studies with long-term follow-ups, neuroimaging, biological markers, and comprehensive neuropsychological assessment are required to understand the mechanism of dance interventions and demonstrate its efficacy for older adults with mild cognitive impairment.
The protocol was registered on PROSPERO (CRD42020173659).
Pregnancy and the postpartum period involve numerous physiological adaptations that enable the development and survival of the offspring. A distinct neural plasticity characterizes the female brain ...during this period, and dynamic structural and functional changes take place that accompany fundamental behavioral adaptations, stimulating the female to progress from an individual with self-directed needs to being responsible for the care of another life. While many animal studies detail these modifications, an emerging body of research reveals the existence of reproduction-related brain plasticity in human mothers too. Additionally, associations with aspects of maternal caregiving point to adaptive changes that benefit a woman’s transition to motherhood. However, the dynamic changes that affect a woman’s brain are not merely adaptive, and they likely confer a vulnerability for the development of mental disorders. Here, we review the changes in brain structure and function that a woman undergoes during the peripartum period, outlining associations between these neural alterations and different aspects of maternal care. We additionally discuss peripartum mood disorders and postpartum psychosis, and review the neuroimaging studies that investigate the neural bases of these conditions.
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