Cerebral cortex最新文献

Working memory depends on the temporary retention and manipulation of information, bridging the gap between short-term memory and information processing functions. When the same working memory task is repeated over several days, it raises the question of whether the rule or task set becomes automated (or proceduralized). The medial prefrontal cortex (mPFC) is crucial for working memory. Yet, the role of the dorsolateral striatum (DLS) in the automation (proceduralization) of rules or task sets remains to be clarified. Using a longitudinal approach of the "delay non-match to place" (DNMP) task in a T-maze combined to chemogenetic inhibition of the mPFC or DLS in mice, we show that the mPFC becomes less critical in the maintenance phase of the task as behavior progressively shifts towards automation. During this phase, the DLS facilitates automated processing. Silencing through chemogenetic inhibition of the DLS during maintenance triggers an adaptation in learning strategies, reactivating a goal-directed behavior. Our findings strengthen memory traces as a dynamic reorganization of neural networks, challenging the classical view of information migration between brain structures. We propose that the memory trace remains in a dormant state-less energy-consuming for the system-while allowing for rapid flexibility in case of task modification.

The hippocampus, in both children and adults, has shown functional specialization along its long axis, with the anterior region associated with emotional processing and the posterior region with spatial memory and navigation. This specialization is also reflected in separate patterns of functional connectivity, but it is unclear whether it is present before birth. Here, we collected resting-state fMRI data in 51 healthy third-trimester fetuses to examine long-axis functional specialization in utero. Using structural regions of interest in the anterior and posterior hippocampus, a seed-based connectivity analysis was performed. We identified distinct networks of functional organization for the anterior and posterior hippocampus. These patterns showed spatial organization and anticorrelation consistent with long-axis specialization. While less mature than those observed in postnatal human and preclinical models, the fetal patterns suggest that the foundation for hippocampal functional differentiation supporting early affective and cognitive processing is already present before birth. Key points We used resting-state fMRI in the third trimester fetal brain to examine the functional projections of the anterior and posterior hippocampus. We identified distinct networks of functional organization that were independently related to the anterior and posterior hippocampus. The groundwork for the specificity of the hippocampus is being laid in utero, with functional anticorrelation contributing to the separation between long-axis segments.

Successful learning often emerges through social interaction: what are the neural and behavioral systems that support this process? This ecological, multimodal study combines functional near-infrared spectroscopy hyperscanning with detailed behavioral and physiological measures in 27 unconstrained social learning interactions. Learning was supported by teacher-learner interbrain synchrony (interpersonal neural synchrony), over regions important for mutual understanding (temporoparietal junction) and communicative coordination (ventral premotor cortex). Joint attention and mutual gaze modulated the interpersonal neural synchrony-learning association in oppositive ways, motivating a dual-process model: during knowledge-building phases, learning is supported by informational uptake dynamic, with high joint attention, low interpersonal neural synchrony in regions for mutual understanding (temporoparietal junction) and coordination (right ventral premotor cortex), and high interpersonal neural synchrony in language-related areas (left ventral premotor cortex). In contrast, during moments of mutual grounding, learning is supported by high mutual gaze and high interpersonal neural synchrony over temporoparietal junction. Cross-brain general linear modeling revealed asymmetric neural dependencies linked to speaking and teaching roles in the left-hemisphere language network. These effects remained after controlling for nodding, gaze, and breathing, indicating that interpersonal neural synchrony reflects true social-cognitive alignment beyond sensorimotor coupling. Taken together, this study shows that successful learning arises from coordinated and nonlinear brain-body dynamics and positions interpersonal neural synchrony as a marker of mutual prediction during communicative social interaction.

The precuneus is a main node of the brain organization, and it is crucial to autonoetic consciousness, body awareness, imagination, and the construction of the self. In humans, it displays a remarkable individual variation, which functional consequences are not yet known. Comparative analyses suggest that the expansion of these areas may have had an evolutionary relevance in Homo sapiens. In this study, we analyzed the MRI scans of 220 individuals ranging from birth to early adulthood, to investigate the morphological changes of the precuneus along ontogeny. Size changes are only detected between birth and 2-3 years of age. In terms of shape, there is a minor increase in dorsal expansion in the same period, although the mean effect is moderate, and general trends are obscured by the pronounced variability. The remarkable individual differences in precuneus morphology are already established at birth. The dorsal extension is a major determinant of such variability in all age groups, although the analysis reveals multiple factors involved. Importantly, the dorsal and ventral regions of the precuneus are largely independent. Longitudinal studies will be necessary to test the details of its morphological changes through ontogeny, as well as surveys investigating its development in prenatal stages.

Action potentials, the primary information units of the nervous system, are usually generated at the axon initial segment. Changes in the length and position of the axon initial segment are associated with alterations in neuronal excitability, but there is only limited information about the baseline structural variability of this compartment. This work provides a comprehensive analysis of the diversity of proximal cell geometries across all anatomical axes of the murine hippocampus, encompassing dorsal-ventral, superficial-deep, and proximal-distal regions. We analyzed the morphology of 3,681 hippocampal pyramidal neurons in 12 animals of both sexes, focusing on axon initial segment length, position, and association with proximal cellular features such as the soma and apical dendrite. Notably, neurons with axon-carrying dendrites were significantly more common in ventral compared to dorsal hippocampal areas, which we also found in two of three human samples. We employed NEURON simulations to assess the functional implications of this variability. Here, variation in proximal geometry contributed only minimally to neuronal homeostasis, but instead increased heterogeneity of response patterns across neurons.

Executive function impairments, particularly in inhibition and cognitive flexibility/shifting, are core features of major depressive disorder (MDD) yet marked interindividual heterogeneity has hindered the identification of reliable brain-based biomarkers. This study aimed to use individualized structural covariance networks (SCNs) analysis, a novel approach reflecting interregional covariation within subjects to characterize the individual differences in brain architecture related to inhibition and shifting ability in first-episode drug-naïve (FEDN) MDD patients. Individualized SCNs were constructed for 283 patients and 81 healthy controls (HCs) using the Brainnetome Atlas, combining probability density estimation and Kullback-Leibler divergence based on regional gray matter volumes. Global and nodal topological properties were estimated. In both MDD and HCs, inhibition-shifting was significantly associated with global and local efficiency and small-worldness. In MDD group, the betweenness centrality of middle frontal gyrus, precentral gyrus, and inferior temporal gyrus were associated with poorer inhibition-shifting, and those of thalamus, cingulate gyrus and inferior frontal gyrus were associated with better inhibition-shifting function. No significant associations between inhibition-shifting and nodal centrality were observed in HCs. These results suggest recruitment of thalamo-cingulate regions in compensation for frontal-temporal organizations affecting inhibition-shifting in FEDN MDD. The individual SCNs may help identify biomarkers for specific executive function in MDD.

A couple of recent neuroimaging studies together led us to hypothesize-perhaps counterintuitively-that the occipital place area (OPA), which supports "visually-guided navigation" (ie making our way through the immediately visible environment, avoiding boundaries and obstacles), develops later than the retrosplenial complex (RSC), which supports "map-based navigation" (ie finding our way from a specific place to some distant, out-of-sight place). But is this true? We directly test this hypothesis using functional magnetic resonance imaging (fMRI) adaptation in 5- and 8-year-old children and ask when OPA and RSC represent left and right information-information that both regions represent in adulthood, albeit for different kinds of navigation. Our results revealed that in 5-year-olds, OPA does not represent left/right information and only does so in 8-year-olds. By contrast, RSC in 5-year-olds represents left/right information, like in 8-year-olds. These findings strongly support our hypothesis: the OPA, which is involved in visually-guided navigation, develops later than the RSC, which supports map-based navigation. This developmental timeline not only demonstrates that OPA and RSC develop at different rates but also strengthens the case that these regions serve distinct roles in adult human navigation-since a single system cannot follow two separate developmental trajectories.

Previous diffusion magnetic resonance imaging (dMRI) research has indicated altered white matter microstructure in autism, but the implicated regions are inconsistent across studies. Such prior work has largely used conventional dMRI analysis methods, including the traditional microstructure model, diffusion tensor imaging (DTI). However, these methods are limited in their ability to precisely map microstructural differences and accurately resolve complex fiber configurations. In our study, we investigated white matter microstructure alterations in autism using the refined along-tract analytic approach, BUndle ANalytics (BUAN), with both an advanced microstructure model, the tensor distribution function (TDF) and DTI. We analyzed dMRI data from 365 autistic and neurotypical participants (5 to 24 yr; 34% female) from 10 cohorts to examine commissural and association tracts. Autism was associated with lower fractional anisotropy and higher diffusivity in localized portions of nearly every commissural and association tract examined; these tracts inter-connected a wide range of brain regions, including frontal, temporal, parietal, and occipital regions. Taken together, BUAN and TDF allow robust and spatially precise mapping of microstructural properties in autism. Our findings rigorously demonstrate that white matter microstructure alterations in autism may be greater within specific regions of individual tracts, and that the implicated tracts are distributed across the brain.

The inhibitory effect of interhemispheric signal propagation (ISP) is believed to be aligned with GABAB receptor mediated inhibitory neurotransmission and related to interhemispheric connectivity. Repetitive Transcranial magnetic stimulation (rTMS) is a safe and potent strategy for altering brain connectivity. However, it remains unclear if rTMS modulates ISP. With pretreatment of baclofen, a GABAB receptor agonist, this study characterized rTMS effects on ISP and the influence of GABAB receptor neurotransmission. ISP was measured with TMS and electroencephalography co-registration (TMS-EEG). Excitatory rTMS (> 5 Hz) was found to increase interhemispheric inhibition indexed by ISP. This effect was reduced by baclofen pretreatment, potentially reflecting competition for GABAB receptors neurotransmission between baclofen and rTMS. Beyond evoked potentials, our data also identified TMS-evoked gamma oscillation as a reliable indicator of intracortical inhibition. These novel findings help to clarify the effects of rTMS on interhemispheric connectivity, which may help to optimize rTMS treatments for various psychiatric disorders.

Breathing not only sustains life but also interacts with emotional states. Mounting evidence suggests that subtle variations in respiratory patterns-including their neural underpinnings-may serve as sensitive indicators of affective processes, yet the specific phases of spontaneous breathing have rarely been studied in detail. Here, we present a cross-sectional, exploratory investigation combining high-temporal-resolution respiratory measures, resting-state magnetoencephalography data, and psychological assessments in 46 healthy adults. Our analysis distinguishes three distinct phases-inspiration, expiration, and the brief but functionally significant post-expiratory pause (PEP). By correlating time-averaged Salience Network connectivity with aggregate respiratory metrics, we identify trait-level associations specific to the PEP in beta and gamma frequencies. Individuals with longer and more variable PEPs show distinct connectivity patterns associated with heightened depression and reduced life satisfaction. Connectivity patterns involving the right insula, bilateral anterior cingulate cortex, and left amygdala show robust correlations with these affective parameters, suggesting that this brief respiratory interval may serve as a window into interoceptive and emotional processing. Our findings highlight the overlooked role of the PEP in capturing meaningful interactions between respiration, neural circuits, and psychological well-being.