Cerebral cortex最新文献

The study of the amygdala and its role in the processing of emotions has become a common focus in neuroscience. The modern expansion of research in this area is partly due to the discovery of a subcortical pathway for the transmission of emotional information and the experimental paradigm that was developed to study it. Groundbreaking experiments during the 90s utilized anatomical, neurophysiological, and behavioral lesion studies in a rodent animal model to uncover the neural circuitry of a simple emotional memory. These studies demonstrated the essential role of a specific monosynaptic pathway in emotional memory, using traditional tools and behavioral methods. The development of an animal model with a simple and appropriate classical conditioning paradigm made experimental investigations into the neural basis of emotion tenable and available to a generation of neuroscientists. These tools and a focus on the amygdala's neural connections and their essential role in emotional memory were a driving force in the explosion of research regarding the amygdala and emotion.

Early-onset Alzheimer's disease (EOAD) is less investigated than the more common late-onset Alzheimer's disease (LOAD) despite its more aggressive course. A cortical signature of EOAD was recently proposed and may facilitate EOAD investigation. Here, we aimed to validate this proposed MRI biomarker of EOAD neurodegeneration in an Appalachian clinical cohort. We also compared differences in EOAD signature atrophy in participants with biomarker-positive EOAD, LOAD, early-onset non-AD pathologies, and cognitively normal individuals. Cortical thinning was reliably detected in eight of nine signature areas of persons with EOAD relative to cognitively normal individuals despite very early disease stage. Additionally, individuals with EOAD showed thinner cortex in most signature regions relative to those with early-onset non-AD pathologies. EOAD and LOAD showed similar cortical atrophy within most EOAD signature regions. Whole-brain vertex-wise cortical analyses supported these findings. Furthermore, signature cortical atrophy showed expected relationships with measures of global and specific cognitive and functional status. This investigation further validates and expands upon the recently defined EOAD signature and suggests its robustness within a rural population, even at early disease stage. Larger scale and longitudinal studies employing this marker of EOAD neurodegeneration are needed to further understand clinical effects and appropriate management of persons with EOAD.

Understanding the goal of an observed action requires computing representations that are invariant to specific instantiations of the action. For example, we can accurately infer the goal of an action even when the agent's desired outcome is not achieved. Observing actions consistently recruits a set of frontoparietal and posterior temporal regions, often labeled the "action observation network." While progress has been made in charting which regions of the action observation network are involved in understanding goals of observed actions, it is not clear where goals are represented independently of outcomes. We used functional magnetic resonance-based multivariate pattern analysis to identify such regions. Human participants (20 females, 12 males) watched videos of successful and failed attempts of actions with different goals involving two different object types. We found that the bilateral anterior inferior parietal lobe and the right ventral premotor cortex distinguished between object-specific action goals regardless of outcomes. The left anterior inferior parietal lobe encodes action goals regardless of both outcomes and object types. Our results provide insights into the neural basis of representing action goals and the different roles of frontoparietal and posterior temporal regions in action understanding.

The cerebral cortex is critical for advanced cognitive functions and relies on a vast network of neurons to carry out its highly intricate neural tasks. Generating cortical neurons in accurate numbers hinges on cell signaling orchestrated by primary cilia to coordinate the proliferation and differentiation of cortical stem cells. While recent research has shed light on multiple ciliary roles in corticogenesis, specific mechanisms downstream of cilia signaling remain largely unexplored. We previously showed that an excess of early-born cortical neurons in mice mutant for the ciliary gene Inpp5e was rescued by re-introducing Gli3 repressor. By comparing expression profiles between Inpp5e and Gli3 mutants, we here identified novel Gli3 target genes. This approach highlighted the transcription factor gene Sall3 and Pappalysin1 (Pappa), a metalloproteinase involved in IGF signaling, as upregulated genes in both mutants. Further examination revealed that Gli3 directly binds to Sall3 and Pappa enhancers and suppresses their activity in the dorsal telencephalon. Collectively, our analyses provide important mechanistic insights into how primary cilia govern the behavior of neural stem cells, ultimately ensuring the production of adequate numbers of neurons during corticogenesis.

Arousal states are thought to influence many aspects of cognition and behavior by broadly modulating neural activity. Many studies have observed arousal-related modulations of alpha (~8 to 15 Hz) and gamma (~30 to 50 Hz) power and coherence in local field potentials across relatively small groups of brain regions. However, the global pattern of arousal-related oscillatory modulation in local field potentials is yet to be fully elucidated. We simultaneously recorded local field potentials in numerous cortical and subcortical regions in the primate brain and assessed oscillatory activity and inter-regional coherence associated with arousal state. In high arousal states, we found a uniquely strong and coherent gamma oscillation between the amygdala and basal forebrain. In low arousal rest-like states, a relative increase in coherence at alpha frequencies was present across sampled brain regions, with the notable exception of the medial temporal lobe. We consider how these patterns of activity may index arousal-related brain states that support the processing of incoming sensory stimuli during high arousal states and memory-related functions during rest.

The present study explored the opposing effects on memory of semantic elaboration and division of attention on learning and recognition of verbal paired associates. Previous work had found that levels of recollection were reduced under divided attention conditions, even after equating expressed elaboration levels between full and divided attention. The present experiments not only confirmed this finding but also found that participants based their expressed levels of elaboration largely on normative values rather than on subjectively achieved levels of elaboration. In terms of related brain processes, experiment 2 used functional magnetic resonance to show that division of attention was associated with reduced levels of both prefrontal and hippocampal activity and with a reduction in connectivity between the anterior hippocampus and medial-orbital regions of the prefrontal cortex. Increased levels of elaboration were associated with increased activity in prefrontal regions immediately after stimulus presentation. Additionally, connectivity between the hippocampus and medial-prefrontal cortex was enhanced by increases in elaboration under full attention but reduced by increases in elaboration under conditions of divided attention. Our results therefore show that two factors influencing memory-elaboration and attention-are mediated largely by processes in the prefrontal cortex, the hippocampus, and the functional connectivity between these two structures.

Value-based decision-making involves weighing costs and benefits. The activity of the medial prefrontal cortex reflects cost-benefit assessments, and the mediodorsal thalamus, reciprocally connected with the medial prefrontal cortex, has increasingly been recognized as an active partner in decision-making. However, the specific role of the interaction between the mediodorsal thalamus and the medial prefrontal cortex in regulating the neuronal activity underlying how costs and benefits influence decision-making remains largely unexplored. We investigated this by training the rats to perform a self-determined decision-making task, where longer nose poke durations resulted in correspondingly larger rewards. Our results showed that the inactivation of either the medial prefrontal cortex or the mediodorsal thalamus significantly impaired rat to invest more nose poke duration for larger rewards. Moreover, optogenetic stimulation of the mediodorsal thalamus-medial prefrontal cortex pathway enhanced rats' motivation for larger rewards, whereas inhibition of this pathway resulted in decreased motivation. Notably, we identified a specific population of neurons in the medial prefrontal cortex that exhibited firing patterns correlated with motivation, and these neurons were modulated by the mediodorsal thalamus-medial prefrontal cortex projection. These findings suggest that the motivation during decision-making is encoded primarily by activity of particular neurons in the medial prefrontal cortex and indicate the crucial role of the mediodorsal thalamus-medial prefrontal cortex pathway in maintaining motivation.

Transcranial magnetic stimulation (TMS) is applied both in research settings and clinically, notably in treating depression through the dorsolateral prefrontal cortex (dlPFC). We have recently shown that transcranial alternating current stimulation of the dlPFC partially entrains muscle sympathetic nerve activity (MSNA) to the stimulus. We, therefore, aimed to further explore the sympathetic properties of the dlPFC, hypothesizing that single-pulse TMS could generate de novo MSNA bursts. Microneurography was performed on the right common peroneal nerve in 12 participants. TMS pulses were then delivered to the ipsilateral dlPFC at resting motor threshold (MT) of the first dorsal interosseous muscle and at powers 20 below, 10 below, 10% above, and 20% above MT. The MT and 10% above MT intensities were also used to stimulate the right motor cortex and shoulder. Comparisons between stimulus intensities at the same site and between sites at the same intensities revealed no differences in MSNA burst frequency, burst incidence, or single MSNA spikes. Most stimulus trains, however, showed reduced burst frequency and incidence from baseline, regardless of site. This suggests that the TMS itself was evoking arousal-based sympathoinhibition, independent of dlPFC influences. It seems the dlPFC is capable of modulating MSNA but cannot directly generate bursts.

Middle-aged and older adults with autism spectrum disorder may be susceptible to accelerated neurobiological changes in striato- and thalamo-cortical tracts due to combined effects of typical aging and existing disparities present from early neurodevelopment. Using magnetic resonance imaging, we employed diffusion-weighted imaging and automated tract-segmentation to explore striato- and thalamo-cortical tract microstructure and volume differences between autistic (n = 29) and typical comparison (n = 33) adults (40 to 70 years old). Fractional anisotropy, mean diffusivity, and tract volumes were measured for 14 striato-cortical and 12 thalamo-cortical tract bundles. Data were examined using linear regressions for group by age effects and group plus age effects, and false discovery rate correction was applied. Following false discovery rate correction, volumes of thalamocortical tracts to premotor, pericentral, and parietal regions were significantly reduced in autism spectrum disorder compared to thalamo-cortical groups, but no group by age interactions were found. Uncorrected results suggested additional main effects of group and age might be present for both tract volume and mean diffusivity across multiple subcortico-cortical tracts. Results indicate parallel rather than accelerated changes during adulthood in striato-cortical and thalamo-cortical tract volume and microstructure in those with autism spectrum disorder relative to thalamo-cortical peers though thalamo-cortical tract volume effects are the most reliable.