Cerebral cortex最新文献

Sensory perception is essential for transforming incoming information in the brain into targeted behavior. Our brains are everlastingly active, and variations in perception are ubiquitously associated with human behavioral performance. Previous studies indicate that changes in spontaneous neural activity within local sensory areas correlate with the perception of ambiguous stimuli. However, the contribution of whole brain spontaneous networks to perception is not well understood. Using an ambiguous tactile temporal discrimination task, we demonstrate that the interaction between whole-brain networks in the seconds of the spontaneous prestimulus period also contributes to perception during the task. Transitions to a frontal and a multifrequency network across the brain are essential for the correct percept. Conversely, incorrect percepts are mainly preceded by transitions to an alpha-parietal network. Brain switches occur faster during the period before stimulus presentation for correct stimuli detection, suggesting the need for enhanced network flexibility during this phase.

Blindness has been shown to induce changes in the structural and functional organization of the brain. However, few studies have investigated the relationship between these structural and functional changes. In this study, we examined cortical thickness within occipital regions of interest in 38 early blind individuals and explored its relationship to functional activation during linguistic processing. Participants engaged in tactile Braille reading and auditory processing tasks involving words, pseudowords, and control conditions to assess various aspects of linguistic processing. Linear mixed models revealed a significant association between cortical thickness and functional activation in the occipital cortex during linguistic tasks. Specifically, lower cortical thickness in the middle occipital gyrus, the calcarine sulcus, and the parieto-occipital sulcus were linked to increased activation during orthographic processing in blind participants (Braille pseudowords vs. Braille nonsense-symbols). Similarly, lower cortical thickness in the calcarine sulcus and parieto-occipital sulcus was associated with greater functional activation during phonological processing (auditory pseudowords vs. auditory control). These findings align with prior research suggesting that structural and functional adaptations in the visual cortex of blind individuals may be influenced by developmental mechanisms such as pruning or myelination. This study highlights the interplay between cortical structure and functional reorganization in the blind brain.

Aging-related dopamine decline has been suggested as a key factor behind individual differences in cognitive decline at older ages. Thus far, the hypothesized age-dopamine-cognition triad has been extrapolated from cross-sectional studies, which cannot uncover change associations. Using data from the longitudinal Cognition, Brain, and Aging (COBRA) study, we examined whether dopamine D2-receptor availability changes are correlated with cognitive changes across individuals in old age. At the first wave, 181 healthy adults aged 64 to 68 years underwent positron emission tomography with 11C-raclopride, magnetic resonance imaging, multiple cognitive tests assessing episodic memory, working memory, and perceptual speed, and mapping of health-related factors. The returnees (n = 129 after 5 years; n = 93 after 10 years) were representative of the parent sample regarding gender composition, educational attainment, cognitive performance, and dopamine D2-receptor status at baseline. Bayesian structural equation modeling revealed mean decline and individual differences in decline for striatal dopamine D2-receptor availability (approximately -5% per decade) and for all three cognitive abilities. Changes in dopamine D2-receptor and a factor of general cognition were positively correlated (r = 0.31, P(r > 0.00) > 0.95). Taken together, these longitudinal findings support that striatal dopamine decline is associated with cognitive aging, possibly reflecting dopamine influences via striato-thalamo-cortical loops on general cognitive functions.

Selective attention requires fast and accurate distractor suppression. We investigated if broadband high-frequency activity (BHA; 80-150 Hz), indicative of local neuronal population dynamics in early sensory cortices, indexes rapid processing of distracting information. In a first experiment we tested whether BHA distinguishes targets from distracting information in a visual search paradigm using tilted gratings as targets and distractors. In a second experiment, we examined whether BHA distractor processing can be trained by statistical regularities. In both experiments, BHA preceded the target enhancement (NT) and distractor suppression (PD; 1-40 Hz) event-related field (ERF) components and distinguished between targets and distractors. Only the BHA but not ERF component amplitude correlated with participants' performance and was higher for lateral distractors versus lateral targets. Furthermore, BHA predicted the strength of the PD. These results indicate that BHA initiates stimulus discrimination via distractor suppression.

This study investigates how attention modulates internal representations in working memory (WM), focusing on the distinct and overlapping neural effects of retrospective and reflective attention using functional magnetic resonance imaging. Participants performed cue-variant WM tasks with retro-cue, refresh-cue, and no-cue trials. The cues instructed participants to either refocus or refresh one of the memorized stimuli (a face or a scene) during the retention interval. Univariate, multivariate, and functional connectivity analyses revealed that retro and refresh cues engaged overlapping brain regions but also exhibited distinct activation patterns. Whole-brain analyses showed overlapping activations and decoding patterns in the ventral occipitotemporal and posterior brain regions. Region-of-interest analyses confirmed the selective modulation of category-specific visual areas by both cues. Functional connectivity analyses further revealed inter-regional correlations between the prefrontal cortex and visual areas for both cues. Importantly, the multivariate pattern analysis revealed distinct effects in the prefrontal and parietal cortices (PFC and PPC): retro cues exerted a greater influence on representational patterns in the PFC, whereas refresh cues had a greater impact on patterns within the PPC. Taken together, this study provides direct evidence that refocusing and refreshing rely on both distinct and overlapping neural mechanisms to support WM maintenance.

Insomnia disorder is the most common sleep disorder affecting millions of people. Brain research has linked insomnia to dysfunction in large-scale brain networks, not only during sleep but also in wakeful rest. Yet, the underlying brain dynamics remain little understood. In the present study, we directly addressed this using a data-driven framework for evaluating time-varying large-scale brain activity. We used functional magnetic imaging to compare participants with insomnia disorder to matched controls with no sleep complaints. Using Hidden Markov modeling (HMM) for a completely data-driven characterization of the brain dynamics of whole-brain activity, we found that insomnia disorder is characterized by significantly reduced switching rates between large-scale brain states. In particular, HMM was used to compare insomnia patients to controls, which showed that their brains spent significantly less time in two whole-brain states-the default mode network and a fronto-parietal network-complemented by increased time spent in a global activation state. Overall, the findings reveal the brain dynamics of insomnia to show that insomnia disorder is characterized by less flexible transitions between brain states at wakeful rest. This highlights the importance of evaluating the spatiotemporal dynamics of brain activity to advance the understanding of the neural underpinnings of insomnia disorder.

Dexterous manual movements require accurate sensorimotor integration; however, understanding how the primary somatosensory cortex (SI) dynamically processes incoming afferent information during such tasks remains limited. Using magnetoencephalography, we investigated somatosensory evoked magnetic fields during two types of finger movement, varying in speed and force exertion. We focused on three SI components-M20, M30, and M38-occurring within 20 to 40 ms post-stimulation. Across all movement conditions, the M20 and M30 amplitudes were significantly reduced when compared with the stationary condition, reflecting sensory gating, whereas M38 was significantly enhanced during both the rotation and pinch tasks. Further analyses revealed that the reduction in M20 was sensitive to movement speed, and that of M30 was influenced by both speed and force. In contrast, the enhancement of M38 was modulated by the finger movement type. These findings suggest that SI activity is not uniformly inhibited during movement, but selectively modulated in a context-dependent manner. The initial components in the SI may reflect the filtering of predictable inputs, whereas M38 could represent the more complex integration associated with skillful finger movement. Thus, our results suggest a dynamic somatosensory processing mechanism that underpins fine motor control.

A substantial subset of cognitively normal (CN) older adults accumulates high burdens of Periventricular (PVWMH) and Deep White Matter Hyperintensities (DWMH), surrogate neuroimaging-markers of cerebral small-vessel disease, while others have minimal or no white matter hyperintensity (WMH). Using multi-modal Magnetic Resonance Imaging (MRI) from National Alzheimer's Coordinating Centre (NACC) (n = 986) and Alzheimer's Disease Neuroimaging Initiative (ADNI) (n = 382) cohorts spanning CN, cognitively impaired (CI), and CI with Alzheimer's etiology (CI-AD) aged 50-94 years, we investigated whether total WMH burden or specifically PVWMH and DWMH, surpassing a threshold disrupts neuroanatomy and cognition. PVWMH and DWMH volume increased exponentially with age, but PVWMH rose twice as fast, with inflection at 61 years. PVWMH > 2.3 mL, independent of age, was associated with structural atrophy (rostralmiddlefrontal, pre/postcentral gyri, lingual-gyrus, nucleus-accumbens), global fiber disintegration, and impairments in executive, attentional, semantic domains. DWMH effects were negligible. Longitudinal mixed-models in NACC and ADNI confirmed that PVWMH progression, not DWMH, predicted accelerated atrophy. PVWMH-related neuroanatomic loss mediates cognitive decline. The 2.3 mL threshold was validated in ADNI3. While both are visible on routine MRI, only PVWMH demonstrated threshold-dependent effects. Progression to ≥2.3 mL marks a threshold, demanding clinical surveillance, vascular-risk management, and recognition of accelerated brain-aging. Neuroimaging-based quantification of PVWMH, combined with domain-specific cognitive testing provides robust measures of clinical surveillance, definitive of brain health.

The capacity to pursue goals, across a series of intermediate stages, is a distinctive achievement of human cognition. Scientific investigations of goal-directed action have emphasized either of two different aspects of this capacity. Research on executive function has described coordination of extended action sequences that solve multi-part problems. Meanwhile, research on voluntary action has emphasized the processes of endogenous generation and autonomy, which are essential for many complex problems, particularly those involving creativity and insight. Because many complex problems can be solved in several ways, choosing and generating a path through the problem space requires a convergence of executive intelligence and volitional control. Here we use fMRI to explore the links between volition and problem-solving in the human brain. Participants performed the Tower of London task (a classical neuropsychological problem-solving challenge) either by generating their own solutions or by following stepwise instructions for each move. We showed behavioral signatures of action planning, associated with a distributed network of frontal and parietal activations, when participants generated their own solutions. We also showed the crucial role of medial frontal cortex, traditionally associated with endogenous generation of very simple willed actions, in goal-directed problem-solving, based on its connectivity with a wider prefrontal network.

Visual perceptual decoding of facial expressions is a key focus in affective neuroscience. Developing a mapping model between visual content and signals is crucial for decoding. Most previous visual decoding models focused on brain responses to static images, neglecting temporal-dynamic feature modeling. Additionally, they input all visual cortices as a whole into the model, overlooking that visual information flows bidirectionally between the lower and higher visual cortices based on bottom-up and top-down visual mechanisms, thus hard to capture bidirectional information between visual regions located in different spatial positions. Here, we present a spatio-temporal bidirectional long short-term memory-based model to decode 3 categories of facial expressions from multi-time functional magnetic resonance imaging data. Specifically, we used the spatio-temporal bidirectional long short-term memory module with the ability to simulate time series to grasp the temporal-dependence from visual cortices, and its forward and backward directions simulate bidirectional information flow between visual cortices to capture the bidirectional spatial information. Experimental outcomes indicate that the mean decoding accuracy employing beta estimates of multi-time response signals (Repetition Times（TR）1-6 1 to 6) from 5 participants is significantly higher than that of other time points signals, unidirectional connections, and publicly available models. These results reveal that our model captures temporal-dependencies and bidirectional spatial information from the visual cortices, enhancing decoding performance.