RESUMEN
Repeated exposure to word forms and meanings improves lexical knowledge acquisition. However, the roles of domain-general and language-specific brain regions during this process remain unclear. To investigate this, we applied intermittent theta burst stimulation over the domain-general (group left dorsolateral prefrontal cortex) and domain-specific (Group L IFG) brain regions, with a control group receiving sham intermittent theta burst stimulation. Intermittent theta burst stimulation effects were subsequently assessed in functional magnetic resonance imaging using an artificial word learning task which consisted of 3 learning phases. A generalized psychophysiological interaction analysis explored the whole brain functional connectivity, while dynamic causal modeling estimated causal interactions in specific brain regions modulated by intermittent theta burst stimulation during repeated exposure. Compared to sham stimulation, active intermittent theta burst stimulation improved word learning performance and reduced activation of the left insula in learning phase 2. Active intermittent theta burst stimulation over the domain-general region increased whole-brain functional connectivity and modulated effective connectivity between brain regions during repeated exposure. This effect was not observed when active intermittent theta burst stimulation was applied to the language-specific region. These findings suggest that the domain-general region plays a crucial role in word formation rule learning, with intermittent theta burst stimulation enhancing whole-brain connectivity and facilitating efficient information exchange between key brain regions during new word learning.
Asunto(s)
Encéfalo , Lenguaje , Imagen por Resonancia Magnética , Estimulación Magnética Transcraneal , Humanos , Masculino , Femenino , Adulto Joven , Estimulación Magnética Transcraneal/métodos , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Adulto , Cognición/fisiología , Mapeo Encefálico , Aprendizaje/fisiología , Ritmo Teta/fisiología , Aprendizaje Verbal/fisiología , Vías Nerviosas/fisiologíaRESUMEN
It is known that the primate amygdala forms projections to many areas of the ipsilateral cortex, but the extent to which it forms connections with the contralateral visual cortex remains less understood. Based on retrograde tracer injections in marmoset monkeys, we report that the amygdala forms widespread projections to the ipsilateral extrastriate cortex, including V1 and areas in both the dorsal (MT, V4T, V3a, 19M, and PG/PFG) and the ventral (VLP and TEO) streams. In addition, contralateral projections were found to target each of the extrastriate areas, but not V1. In both hemispheres, the tracer-labeled neurons were exclusively located in the basolateral nuclear complex. The number of labeled neurons in the contralateral amygdala was small relative to the ipsilateral connection (1.2% to 5.8%). The percentage of contralateral connections increased progressively with hierarchical level. An injection in the corpus callosum demonstrated that at least some of the amygdalo-cortical connections cross through this fiber tract, in addition to the previously documented path through the anterior commissure. Our results expand knowledge of the amygdalofugal projections to the extrastriate cortex, while also revealing pathways through which visual stimuli conveying affective content can directly influence early stages of neural processing in the contralateral visual field.
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Amígdala del Cerebelo , Callithrix , Corteza Visual , Animales , Corteza Visual/fisiología , Amígdala del Cerebelo/fisiología , Masculino , Vías Nerviosas/fisiología , Lateralidad Funcional/fisiología , Femenino , Neuronas/fisiología , Cuerpo Calloso/fisiología , Técnicas de Trazados de Vías Neuroanatómicas , Vías Visuales/fisiologíaRESUMEN
This study investigated whether the electric field magnitude (E-field) delivered to the left dorsolateral prefrontal cortex (L-DLPFC) changes resting-state brain activity and the L-DLPFC resting-state functional connectivity (rsFC), given the variability in tDCS response and lack of understanding of how rsFC changes. Twenty-one healthy participants received either 2 mA anodal or sham tDCS targeting the L-DLPFC for 10 min. Brain imaging was conducted before and after stimulation. The fractional amplitude of low-frequency fluctuation (fALFF), reflecting resting brain activity, and the L-DLPFC rsFC were analyzed to investigate the main effect of tDCS, main effect of time, and interaction effects. The E-field was estimated by modeling tDCS-induced individual electric fields and correlated with fALFF and L-DLPFC rsFC. Anodal tDCS increased fALFF in the left rostral middle frontal area and decreased fALFF in the midline frontal area (FWE p < 0.050), whereas sham induced no changes. Overall rsFC decreased after sham (positive and negative connectivity, p = 0.001 and 0.020, respectively), with modest and nonsignificant changes after anodal tDCS (p = 0.063 and 0.069, respectively). No significant differences in local rsFC were observed among the conditions. Correlations were observed between the E-field and rsFC changes in the L-DLPFC (r = 0.385, p = 0.115), left inferior parietal area (r = 0.495, p = 0.037), and right lateral visual area (r = 0.683, p = 0.002). Single-session tDCS induced resting brain activity changes and may help maintain overall rsFC. The E-field in the L-DLPFC is associated with rsFC changes in both proximal and distally connected brain regions to the L-DLPFC.
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Estudios Cruzados , Corteza Prefontal Dorsolateral , Imagen por Resonancia Magnética , Estimulación Transcraneal de Corriente Directa , Humanos , Estimulación Transcraneal de Corriente Directa/métodos , Masculino , Femenino , Adulto , Adulto Joven , Corteza Prefontal Dorsolateral/fisiología , Vías Nerviosas/fisiología , Corteza Prefrontal/fisiología , Corteza Prefrontal/diagnóstico por imagen , Mapeo EncefálicoRESUMEN
Understanding the brain's mechanisms in individuals with obesity is important for managing body weight. Prior neuroimaging studies extensively investigated alterations in brain structure and function related to body mass index (BMI). However, how the network communication among the large-scale brain networks differs across BMI is underinvestigated. This study used diffusion magnetic resonance imaging of 290 young adults to identify links between BMI and brain network mechanisms. Navigation efficiency, a measure of network routing, was calculated from the structural connectivity computed using diffusion tractography. The sensory and frontoparietal networks indicated positive associations between navigation efficiency and BMI. The neurotransmitter association analysis identified that serotonergic and dopaminergic receptors, as well as opioid and norepinephrine systems, were related to BMI-related alterations in navigation efficiency. The transcriptomic analysis found that genes associated with network routing across BMI overlapped with genes enriched in excitatory and inhibitory neurons, specifically, gene enrichments related to synaptic transmission and neuron projection. Our findings suggest a valuable insight into understanding BMI-related alterations in brain network routing mechanisms and the potential underlying cellular biology, which might be used as a foundation for BMI-based weight management.
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Índice de Masa Corporal , Encéfalo , Humanos , Masculino , Adulto Joven , Femenino , Adulto , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Imagen de Difusión Tensora , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/fisiología , Conectoma , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiología , Obesidad/diagnóstico por imagen , Obesidad/fisiopatología , Obesidad/patología , Imagen de Difusión por Resonancia MagnéticaRESUMEN
To ensure survival, animals must sometimes suppress fear responses triggered by potential threats during feeding. However, the mechanisms underlying this process remain poorly understood. In the current study, we demonstrated that when fear-conditioned stimuli (CS) were presented during food consumption, a neural projection from lateral hypothalamic (LH) GAD2 neurons to nucleus incertus (NI) relaxin-3 (RLN3)-expressing neurons was activated, leading to a reduction in CS-induced freezing behavior in male mice. LHGAD2 neurons established excitatory connections with the NI. The activity of this neural circuit, including NIRLN3 neurons, attenuated CS-induced freezing responses during food consumption. Additionally, the lateral mammillary nucleus (LM), which received NIRLN3 projections, along with RLN3 signaling in the LM, mediated the decrease in freezing behavior. Collectively, this study identified an LHGAD2-NIRLN3-LM circuit involved in modulating fear responses during feeding, thereby enhancing our understanding of how animals coordinate nutrient intake with threat avoidance.
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Miedo , Animales , Miedo/fisiología , Masculino , Ratones , Hipotálamo/fisiología , Hipotálamo/metabolismo , Relaxina/metabolismo , Neuronas/fisiología , Neuronas/metabolismo , Ratones Endogámicos C57BL , Vías Nerviosas/fisiología , Ingestión de Alimentos/fisiología , Condicionamiento Clásico/fisiología , Área Hipotalámica Lateral/fisiología , Área Hipotalámica Lateral/metabolismoRESUMEN
Structural connectivity (SC) between distant regions of the brain support synchronized function known as functional connectivity (FC) and give rise to the large-scale brain networks that enable cognition and behavior. Understanding how SC enables FC is important to understand how injuries to SC may alter brain function and cognition. Previous work evaluating whole-brain SC-FC relationships showed that SC explained FC well in unimodal visual and motor areas, but only weakly in association areas, suggesting a unimodal-heteromodal gradient organization of SC-FC coupling. However, this work was conducted in group-averaged SC/FC data. Thus, it could not account for inter-individual variability in the locations of cortical areas and white matter tracts. We evaluated the correspondence of SC and FC within three highly sampled healthy participants. For each participant, we collected 78 min of diffusion-weighted MRI for SC and 360 min of resting state fMRI for FC. We found that FC was best explained by SC in visual and motor systems, as well as in anterior and posterior cingulate regions. A unimodal-to-heteromodal gradient could not fully explain SC-FC coupling. We conclude that the SC-FC coupling of the anterior-posterior cingulate circuit is more similar to unimodal areas than to heteromodal areas.
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Encéfalo , Imagen por Resonancia Magnética , Vías Nerviosas , Humanos , Masculino , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Adulto , Femenino , Imagen por Resonancia Magnética/métodos , Vías Nerviosas/fisiología , Vías Nerviosas/diagnóstico por imagen , Mapeo Encefálico/métodos , Adulto Joven , Imagen de Difusión por Resonancia Magnética , Descanso/fisiología , Sustancia Blanca/fisiología , Sustancia Blanca/diagnóstico por imagenRESUMEN
BACKGROUND: There is growing interest in understanding the dynamic functional connectivity (DFC) between distributed brain regions. However, it remains challenging to reliably estimate the temporal dynamics from resting-state functional magnetic resonance imaging (rs-fMRI) due to the limitations of current methods. NEW METHODS: We propose a new model called HDP-HSMM-BPCA for sparse DFC analysis of high-dimensional rs-fMRI data, which is a temporal extension of probabilistic principal component analysis using Bayesian nonparametric hidden semi-Markov model (HSMM). Specifically, we utilize a hierarchical Dirichlet process (HDP) prior to remove the parametric assumption of the HMM framework, overcoming the limitations of the standard HMM. An attractive superiority is its ability to automatically infer the state-specific latent space dimensionality within the Bayesian formulation. RESULTS: The experiment results of synthetic data show that our model outperforms the competitive models with relatively higher estimation accuracy. In addition, the proposed framework is applied to real rs-fMRI data to explore sparse DFC patterns. The findings indicate that there is a time-varying underlying structure and sparse DFC patterns in high-dimensional rs-fMRI data. COMPARISON WITH EXISTING METHODS: Compared with the existing DFC approaches based on HMM, our method overcomes the limitations of standard HMM. The observation model of HDP-HSMM-BPCA can discover the underlying temporal structure of rs-fMRI data. Furthermore, the relevant sparse DFC construction algorithm provides a scheme for estimating sparse DFC. CONCLUSION: We describe a new computational framework for sparse DFC analysis to discover the underlying temporal structure of rs-fMRI data, which will facilitate the study of brain functional connectivity.
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Teorema de Bayes , Encéfalo , Imagen por Resonancia Magnética , Imagen por Resonancia Magnética/métodos , Humanos , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Descanso/fisiología , Procesamiento de Imagen Asistido por Computador/métodos , Mapeo Encefálico/métodos , Cadenas de Markov , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiología , Análisis de Componente Principal , Algoritmos , Modelos Neurológicos , Simulación por ComputadorRESUMEN
The cerebral cortex contains multiple, distinct areas that individually perform specific computations. A particular strength of the cortex is the communication of signals between cortical areas that allows the outputs of these compartmentalized computations to influence and build on each other, thereby dramatically increasing the processing power of the cortex and its role in sensation, action, and cognition. Determining how the cortex communicates signals between individual areas is, therefore, critical for understanding cortical function. Historically, corticocortical communication was thought to occur exclusively by direct anatomical connections between areas that often sequentially linked cortical areas in a hierarchical fashion. More recently, anatomical, physiological, and behavioral evidence is accumulating indicating a role for the higher-order thalamus in corticocortical communication. Specifically, the transthalamic pathway involves projections from one area of the cortex to neurons in the higher-order thalamus that, in turn, project to another area of the cortex. Here, we consider the evidence for and implications of having two routes for corticocortical communication with an emphasis on unique processing available in the transthalamic pathway and the consequences of disorders and diseases that affect transthalamic communication.
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Corteza Cerebral , Vías Nerviosas , Tálamo , Corteza Cerebral/fisiología , Humanos , Animales , Tálamo/fisiología , Vías Nerviosas/fisiologíaRESUMEN
Primates must adapt to changing environments by optimizing their behavior to make beneficial choices. At the core of adaptive behavior is the orbitofrontal cortex (OFC) of the brain, which updates choice value through direct experience or knowledge-based inference. Here, we identify distinct neural circuitry underlying these two separate abilities. We designed two behavioral tasks in which two male macaque monkeys updated the values of certain items, either by directly experiencing changes in stimulus-reward associations, or by inferring the value of unexperienced items based on the task's rules. Chemogenetic silencing of bilateral OFC combined with mathematical model-fitting analysis revealed that monkey OFC is involved in updating item value based on both experience and inference. In vivo imaging of chemogenetic receptors by positron emission tomography allowed us to map projections from the OFC to the rostromedial caudate nucleus (rmCD) and the medial part of the mediodorsal thalamus (MDm). Chemogenetic silencing of the OFC-rmCD pathway impaired experience-based value updating, while silencing the OFC-MDm pathway impaired inference-based value updating. Our results thus demonstrate dissociable contributions of distinct OFC projections to different behavioral strategies, and provide new insights into the neural basis of value-based adaptive decision-making in primates.
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Corteza Prefrontal , Animales , Masculino , Corteza Prefrontal/fisiología , Corteza Prefrontal/diagnóstico por imagen , Conducta Animal/fisiología , Adaptación Psicológica/fisiología , Núcleo Caudado/fisiología , Núcleo Caudado/diagnóstico por imagen , Recompensa , Tomografía de Emisión de Positrones , Macaca mulatta , Vías Nerviosas/fisiología , Conducta de Elección/fisiología , Toma de Decisiones/fisiología , Tálamo/fisiología , Tálamo/diagnóstico por imagen , Mapeo Encefálico/métodosRESUMEN
Enactive cognition emphasizes co-constructive roles of humans and their environment in shaping cognitive processes. It is specifically engaged in the mental simulation of behaviors, enhancing the connection between perception and action. Here we investigated the core network of brain regions involved in enactive cognition as applied to mental simulations of physical exercise. We used a neuroimaging paradigm in which participants (N = 103) were required to project themselves running or plogging (running while picking-up litter) along an image-guided naturalistic trail. Using both univariate and multivariate brain imaging analyses, we find that a broad spectrum of brain activation discriminates between the mental simulation of plogging versus running. Critically, we show that self-reported ratings of daily life running engagement and the quality of mental simulation (how well participants were able to imagine themselves running) modulate the brain reactivity to plogging versus running. Finally, we undertook functional connectivity analyses centered on the insular cortex, which is a key region in the dynamic interplay between neurocognitive processes. This analysis revealed increased positive and negative patterns of insular-centered functional connectivity in the plogging condition (as compared to the running condition), thereby confirming the key role of the insular cortex in action simulation involving complex sets of mental mechanisms. Taken together, the present findings provide new insights into the brain networks involved in the enactive mental simulation of physical exercise.
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Mapeo Encefálico , Encéfalo , Imagen por Resonancia Magnética , Carrera , Humanos , Masculino , Carrera/fisiología , Femenino , Adulto Joven , Adulto , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Imaginación/fisiología , Vías Nerviosas/fisiología , Vías Nerviosas/diagnóstico por imagenRESUMEN
Current concepts of corticothalamic organization in the mammalian brain are mainly based on sensory systems, with less focus on circuits for higher-order cognitive functions. In sensory systems, first-order thalamic relays are driven by subcortical inputs and modulated by cortical feedback, while higher-order relays receive strong excitatory cortical inputs. The applicability of these principles beyond sensory systems is uncertain. We investigated mouse prefronto-thalamic projections to the midline thalamus, revealing distinct top-down control. Unlike sensory systems, this pathway relies on indirect modulation via the thalamic reticular nucleus (TRN). Specifically, the prelimbic area, which influences emotional and motivated behaviors, impacts instrumental avoidance responses through direct and indirect projections to the paraventricular thalamus. Both pathways promote defensive states, but the indirect pathway via the TRN is essential for organizing avoidance decisions through disinhibition. Our findings highlight intra-thalamic circuit dynamics that integrate cortical cognitive signals and their role in shaping complex behaviors.
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Reacción de Prevención , Ratones Endogámicos C57BL , Vías Nerviosas , Animales , Ratones , Reacción de Prevención/fisiología , Masculino , Vías Nerviosas/fisiología , Tálamo/fisiología , Núcleos Talámicos de la Línea Media/fisiología , Corteza Cerebral/fisiologíaRESUMEN
The functional organization of the frontal lobe is a source of debate, focusing on broad functional subdivisions, large-scale networks, or local refined specificities. Multiple neurocognitive models have tried to explain how functional interactions between cingulate and lateral frontal regions contribute to decision making and cognitive control, but their neuroanatomical bases remain unclear. We provide a detailed description of the functional connectivity between cingulate and lateral frontal regions using resting-state functional MRI in rhesus macaques. The analysis focuses on the functional connectivity of the rostral part of the cingulate sulcus with the lateral frontal cortex. Data-driven and seed-based analysis revealed three clusters within the cingulate sulcus organized along the rostro-caudal axis: the anterior, mid, and posterior clusters display increased functional connectivity with, respectively, the anterior lateral prefrontal regions, face-eye lateral frontal motor cortical areas, and hand lateral frontal motor cortex. The location of these clusters can be predicted in individual subjects based on morphological landmarks. These results suggest that the anterior cluster corresponds to the anterior cingulate cortex, whereas the posterior clusters correspond to the face-eye and hand cingulate motor areas within the anterior midcingulate cortex. These data provide a comprehensive framework to identify cingulate subregions based on functional connectivity and local organization.
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Mapeo Encefálico , Giro del Cíngulo , Macaca mulatta , Imagen por Resonancia Magnética , Vías Nerviosas , Giro del Cíngulo/fisiología , Giro del Cíngulo/diagnóstico por imagen , Animales , Imagen por Resonancia Magnética/métodos , Mapeo Encefálico/métodos , Masculino , Vías Nerviosas/fisiología , Vías Nerviosas/diagnóstico por imagen , Lóbulo Frontal/fisiología , Lóbulo Frontal/diagnóstico por imagen , FemeninoRESUMEN
The executive control process of monitoring information in working memory depends on the mid-dorsolateral prefrontal cortical region (cytoarchitectonic areas 46 and 9/46) in interaction with the hippocampal memory system. Anatomical studies demonstrated strong connectivity between the mid-dorsolateral prefrontal cortex and the medial parietal area PGm that lies on the precuneus. Area PGm is also strongly connected with the attentional system on the lateral inferior parietal lobule (area PG) and the limbic retrosplenial/posterior cingulate region that interacts with the hippocampal memory system. Thus, in terms of anatomical connectivity, area PGm appears to be a critical node for the integration of executive control processing from the prefrontal cortex with the online attentional and memory related processing. This hypothesis was tested in macaque monkeys with the crossed unilateral lesion methodology. A unilateral lesion in the mid-dorsolateral prefrontal cortex was combined with a unilateral lesion in area PGm in the opposite hemisphere. The results demonstrated an impairment on the externally ordered working memory task that assesses the monitoring of information in working memory. Thus, the medial parietal area PGm is a critical node in mediating the functional interaction between the prefrontal region for the executive control process of monitoring information and the memory system.
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Memoria a Corto Plazo , Lóbulo Parietal , Animales , Memoria a Corto Plazo/fisiología , Lóbulo Parietal/fisiología , Masculino , Vías Nerviosas/fisiología , Macaca mulatta , Corteza Prefontal Dorsolateral/fisiología , Corteza Prefrontal/fisiologíaRESUMEN
Speech perception requires the binding of spatiotemporally disjoint auditory-visual cues. The corresponding brain network-level information processing can be characterized by two complementary mechanisms: functional segregation which refers to the localization of processing in either isolated or distributed modules across the brain, and integration which pertains to cooperation among relevant functional modules. Here, we demonstrate using functional magnetic resonance imaging recordings that subjective perceptual experience of multisensory speech stimuli, real and illusory, are represented in differential states of segregation-integration. We controlled the inter-subject variability of illusory/cross-modal perception parametrically, by introducing temporal lags in the incongruent auditory-visual articulations of speech sounds within the McGurk paradigm. The states of segregation-integration balance were captured using two alternative computational approaches. First, the module responsible for cross-modal binding of sensory signals defined as the perceptual binding network (PBN) was identified using standardized parametric statistical approaches and their temporal correlations with all other brain areas were computed. With increasing illusory perception, the majority of the nodes of PBN showed decreased cooperation with the rest of the brain, reflecting states of high segregation but reduced global integration. Second, using graph theoretic measures, the altered patterns of segregation-integration were cross-validated.
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Encéfalo , Imagen por Resonancia Magnética , Percepción del Habla , Percepción Visual , Humanos , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Masculino , Femenino , Adulto , Adulto Joven , Percepción del Habla/fisiología , Percepción Visual/fisiología , Mapeo Encefálico , Estimulación Acústica , Red Nerviosa/fisiología , Red Nerviosa/diagnóstico por imagen , Estimulación Luminosa/métodos , Ilusiones/fisiología , Vías Nerviosas/fisiología , Percepción Auditiva/fisiologíaRESUMEN
Mental rotation has emerged as an important predictor for success in science, technology, engineering, and math fields. Previous studies have shown that males and females perform mental rotation tasks differently. However, how the brain functions to support this difference remains poorly understood. Recent advancements in neuroimaging techniques have enabled the identification of sex differences in large-scale brain network connectivity. Using a classic mental rotation task with functional magnetic resonance imaging, the present study investigated whether there are any sex differences in large-scale brain network connectivity for mental rotation performance. Our results revealed that, relative to females, males exhibited less cross-network interaction (i.e. lower inter-network connectivity and participation coefficient) of the visual network but more intra-network integration (i.e. higher intra-network connectivity and local efficiency) and cross-network interaction (i.e. higher inter-network connectivity and participation coefficient) of the salience network. Across all participants, mental rotation performance was negatively correlated with cross-network interaction (i.e. participation coefficient) of the visual network, was positively correlated with cross-network interaction (i.e. inter-network connectivity) of the salience network, and was positively correlated with intra-network integration (i.e. local efficiency) of the somato-motor network. Interestingly, the cross-network integration indexes of both the visual and salience networks significantly mediated sex difference in mental rotation performance. The present findings suggest that large-scale brain network connectivity may constitute an essential neural basis for sex difference in mental rotation, and highlight the importance of considering sex as a research variable in investigating the complex network underpinnings of spatial cognition.
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Encéfalo , Imagen por Resonancia Magnética , Caracteres Sexuales , Humanos , Masculino , Femenino , Adulto Joven , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Adulto , Red Nerviosa/fisiología , Red Nerviosa/diagnóstico por imagen , Imaginación/fisiología , Rotación , Mapeo Encefálico/métodos , Percepción Espacial/fisiología , Vías Nerviosas/fisiologíaRESUMEN
Carrying out any everyday task, be it driving in traffic, conversing with friends or playing basketball, requires rapid selection, integration and segregation of stimuli from different sensory modalities. At present, even the most advanced artificial intelligence-based systems are unable to replicate the multisensory processes that the human brain routinely performs, but how neural circuits in the brain carry out these processes is still not well understood. In this Perspective, we discuss recent findings that shed fresh light on the oscillatory neural mechanisms that mediate multisensory integration (MI), including power modulations, phase resetting, phase-amplitude coupling and dynamic functional connectivity. We then consider studies that also suggest multi-timescale dynamics in intrinsic ongoing neural activity and during stimulus-driven bottom-up and cognitive top-down neural network processing in the context of MI. We propose a new concept of MI that emphasizes the critical role of neural dynamics at multiple timescales within and across brain networks, enabling the simultaneous integration, segregation, hierarchical structuring and selection of information in different time windows. To highlight predictions from our multi-timescale concept of MI, real-world scenarios in which multi-timescale processes may coordinate MI in a flexible and adaptive manner are considered.
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Encéfalo , Humanos , Encéfalo/fisiología , Animales , Red Nerviosa/fisiología , Vías Nerviosas/fisiología , Modelos NeurológicosRESUMEN
The convergence of conditioned and unconditioned stimuli (CS and US) into the lateral amygdala (LA) serves as a substrate for an adequate fear response in vivo. This well-known Pavlovian paradigm modulates the synaptic plasticity of neurons, as can be proved by the long-term potentiation (LTP) phenomenon in vitro. Although there is an increasing body of evidence for the existence of LTP in the amygdala, only a few studies were able to show a reliable long-term depression (LTD) of excitation in this structure. We have used coronal brain slices and conducted patch-clamp recordings in pyramidal neurons of the lateral amygdala (LA). After obtaining a stable baseline excitatory postsynaptic current (EPSC) response at a holding potential of -70 mV, we employed a paired-pulse paradigm at 1 Hz at the same membrane potential and could observe a reliable LTD. The different durations of stimulation (ranging between 1.5-24 min) were tested first in the same neuron, but the intensity was kept constant. The latter paradigm resulted in a step-wise LTD with a gradually increasing magnitude under these conditions.
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Amígdala del Cerebelo , Potenciales Postsinápticos Excitadores , Depresión Sináptica a Largo Plazo , Técnicas de Placa-Clamp , Depresión Sináptica a Largo Plazo/fisiología , Animales , Potenciales Postsinápticos Excitadores/fisiología , Amígdala del Cerebelo/fisiología , Masculino , Células Piramidales/fisiología , Estimulación Eléctrica , Ratas , Ratas Wistar , Corteza Cerebral/fisiología , Vías Nerviosas/fisiología , Técnicas In VitroRESUMEN
PURPOSE: Pineal gland (PG) is a structure located in the midline of the brain, and is considered as a main part of the epithalamus. There are reports on the role of this area for brain function by hormone secretion, as well as few reports on its role in brain cognition. However, little knowledge is available on the PG, and in particular on the structural connectivity of this region with the other brain structures. METHODS: Using diffusion-weighted images collected by a 3T MRI scanner, and using a sample of 61 (29 F) mentally and physically healthy young individuals in the age range of 20-30 years old, we tried to extract the white matter bundles connected to the PG. Based on prior knowledge, seven target bundles were suggested to be between the PG body and the PG roots, Pons, Periventricular region, thalamus, caudate, lentiform, suprachiasmatic nuclei, and the supercervical ganglia. RESULTS: Nearly all the target bundles were successfully extracted, with the exception of the lentiform. Rate of identification of the tracts was different, with the bundle between the PG body and roots having the highest identification rate (97%); then it was with the Pons (70%), Periventricular region (57%), SCN (55%), left thalamus (52%), right thalamus (47%), left caudate (27%) and right caudate (22%). CONCLUSION: This study is an attempt to expand our knowledge on the neuroanatomy of the PG, which might help for identifying further roles for it in brain functionality, and also be a help for the treatment of some disorders in the future.
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Imagen de Difusión Tensora , Glándula Pineal , Sustancia Blanca , Humanos , Glándula Pineal/anatomía & histología , Glándula Pineal/diagnóstico por imagen , Masculino , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/anatomía & histología , Adulto , Femenino , Adulto Joven , Voluntarios Sanos , Vías Nerviosas/anatomía & histología , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiologíaRESUMEN
Chronic predator stress (CPS) is an important and ecologically relevant tool for inducing anhedonia in animals, but the neural circuits underlying the associated neurobiological changes remain to be identified. Using cell-type-specific manipulations, we found that corticotropin-releasing hormone (CRH) neurons in the medial subthalamic nucleus (mSTN) enhance struggle behaviors in inescapable situations and lead to anhedonia, predominately through projections to the external globus pallidus (GPe). Recordings of in vivo neuronal activity revealed that CPS distorted mSTN-CRH neuronal responsivity to negative and positive stimuli, which may underlie CPS-induced behavioral despair and anhedonia. Furthermore, we discovered presynaptic inputs from the bed nucleus of the stria terminalis (BNST) to mSTN-CRH neurons projecting to the GPe that were enhanced following CPS, and these inputs may mediate such behaviors. This study identifies a neurocircuitry that co-regulates escape response and anhedonia in response to predator stress. This new understanding of the neural basis of defensive behavior in response to predator stress will likely benefit our understanding of neuropsychiatric diseases.
Asunto(s)
Anhedonia , Hormona Liberadora de Corticotropina , Neuronas , Estrés Psicológico , Núcleo Subtalámico , Animales , Hormona Liberadora de Corticotropina/metabolismo , Estrés Psicológico/fisiopatología , Estrés Psicológico/metabolismo , Neuronas/fisiología , Núcleo Subtalámico/fisiología , Anhedonia/fisiología , Ratones , Masculino , Ratones Endogámicos C57BL , Reacción de Fuga/fisiología , Vías Nerviosas/fisiología , Núcleos Septales/fisiología , Núcleos Septales/metabolismo , Globo Pálido/fisiologíaRESUMEN
Cotransmission, meaning the release of multiple neurotransmitters from one synapse, allows for increased diversity of signaling in the brain. Dopamine (DA) and γ-aminobutyric acid (GABA) are known to coexpress in many regions such as the olfactory bulb and the ventral tegmental area. Tuberoinfundibular dopaminergic neurons (TIDA) in the arcuate nucleus of the hypothalamus (Arc) project to the median eminence (ME) and regulate prolactin release from the pituitary, and prior work suggests dopaminergic Arc neurons also cotransmit GABA. However, the extent of cotransmission, and the projection patterns of these neurons have not been fully revealed. Here, we used a genetic intersectional reporter expression approach to selectively label cells that express both tyrosine hydroxylase (TH) and vesicular GABA transporter (VGAT). Through this approach, we identified cells capable of both DA and GABA cotransmission in the Arc, periventricular (Pe), paraventricular (Pa), ventromedial, and the dorsolateral hypothalamic nuclei, in addition to a novel population in the caudate putamen. The highest density of labeled cells was in the Arc, 6.68% of DAPI-labeled cells at Bregma -2.06 mm, and in the Pe, 2.83% of DAPI-labeled cells at Bregma -1.94 mm. Next, we evaluated the projections of these DA/GABA cells by injecting an mCherry virus that fluoresces in DA/GABA cells. We observed a cotransmitting DA/GABA population, with projections within the Arc, and to the Pa and ME. These data suggest DA/GABA Arc neurons are involved in prolactin release as a subset of TIDA neurons. Further investigation will elucidate the interactions of dopamine and GABA in the hypothalamus.NEW & NOTEWORTHY Cotransmitting dopaminergic (DA) and γ-aminobutyric acid (GABA)ergic (DA/GABA) neurons contribute to the complexity of neural circuits. Using a new genetic technique, we characterized the locations, density, and projections of hypothalamic DA/GABA neurons. DA/GABA cells are mostly in the arcuate nucleus (Arc), from which they project locally within the arcuate, to the median eminence (ME), and to the paraventricular (Pa) nucleus. There is also a small and previously unreported group of DA/GABA cells in the caudate putamen.