Journal of Neuroscience最新文献

Rodents manipulate their vibrissae to actively interact with their environment. The vibrissa area of the primary motor cortex (vM1) is a central player in orchestrating the rhythmic whisker movement, known as "whisking," and previous in vivo electrophysiological studies have revealed the presence of neurons exhibiting activity modulation related to whisking within vM1. vM1 innervates premotoneurons regulating whisking in the reticular nucleus via corticofugal fibers originating exclusively from pyramidal tract (PT) neurons in Layer 5 (L5), while this layer also contains another pyramidal cell subclass, intratelencephalic (IT) neurons, whose axons remain confined within the telencephalon. However, the potential diversity among these morphological subtypes involved in whisking execution remains largely unexplored. Here, we demonstrate functional heterogeneity among both PT and IT neurons in the execution of whisker movement. Juxtacellular recording within L5 of vM1 in head-fixed, awake male mice during self-initiated whisking, followed by post hoc immunohistochemistry, revealed that firing activity in a substantial proportion of neurons was significantly correlated with parameters of whisker movement, such as whisking amplitude and midpoint. Among these, approximately half were activated during whisking, while the rest preferred nonwhisking periods, with these modulation patterns corresponding to their baseline firing properties at rest. Although both types of whisking-related neurons were present within PT and IT populations, whisking-related activation was relatively prevalent in PT neurons, whereas nonwhisking preference was more typical of IT cells. Our findings highlight the functional heterogeneity within morphologically defined neuronal subclasses, providing new insights into the intricate cortical mechanisms underlying various rhythmic movements.

The recent past helps us predict and prepare for the near future. Such preparation relies on working memory (WM) which actively maintains and manipulates information providing a temporal bridge. Numerous studies have shown that recently presented visual stimuli can be decoded from fMRI signals in visual cortex (VC) and the intraparietal sulcus (IPS), suggesting that these areas sustain the recent past. Yet, in many cases, concrete, sensory signals of past information must be transformed into the abstract codes to guide future cognition. However, this process remains poorly understood. Here, human participants of either sex used WM to maintain a separate spatial location in each hemifield wherein locations were embedded in a learned spatial sequence. On each trial, participants made a sequence-match decision to a probe and then updated their WM with the probe. The same abstract sequence guided judgments in each hemifield, allowing the separate detection of concrete spatial locations (hemifield-specific) and abstract sequence positions (hemifield-general) and also tracking of representations of the past (last location/position) and future (next location/position). Consistent with previous reports, concrete past locations held in WM could be decoded from VC and IPS. Moreover, in anticipation of the probe, representations shifted from past to future locations in both areas. Critically, we observed abstract coding of future sequence positions in the IPS whose magnitude related to speeded performance. These data suggest that the IPS sustains abstract codes to facilitate future preparation and reveal a transformation of the sensory past into abstract codes guiding future behavior.

The neural signatures of preparing overt eye movements and directing covert spatial attention overlap as they recruit the same brain areas. Yet, these neural signatures are dissociable at the single cell level: Specific cells within visuo-oculomotor areas are exclusively involved in motor preparation or covert attention. Nevertheless, it has been proposed that many cells in visuo-oculomotor areas are involved in both motor preparation and covert attention, and consequently their neural signatures should functionally overlap to a large degree. Here, we directly tested this proposal: We combined human (both sexes) EEG with sensitive decoding techniques to investigate whether the neural signatures of preparatory overt and covert attention are dissociable across large-scale neuronal populations. We found that neural decoding reliably discerned whether overt or covert attention was shifted well before saccade initiation. Further, inverted encoding modeling revealed earlier and sharper spatially selective activity in preparatory overt than in covert attention. We then asked whether preparatory overt attention achieved sharper spatial selectivity by using "more-of-the-same" covert attention or by recruiting an additional neural process. Cross-decoding results demonstrated that preparatory overt attention recruited at least one additional, frontal process. This additional spatially selective process emerged early and likely reflects motor preparation or predictive remapping. To summarize, we found that the neural signatures of overt and covert attention overlap, yet diverge rapidly, in part because overt attention employs an additional spatially selective neural process. Extending beyond a dissociation on the single-cell level, our findings demonstrate that population-level neural activity dissociates preparatory overt from covert attention.

Psychedelics profoundly alter subjective experience and brain dynamics. Brain oscillations express signatures of near-critical dynamics, relevant for healthy function. Alterations in the proximity to criticality have been suggested to underlie the experiential and neurological effects of psychedelics. Here, we investigate the effects of a psychedelic substance (DMT) on the criticality of brain oscillations, and in relation to subjective experience, in humans of either sex. We find that DMT shifts the dynamics of brain oscillations away from criticality in alpha and adjacent frequency bands. In this context, entropy is increased while complexity is reduced. We find that the criticality-shifts observed in alpha and theta bands correlate with the intensity ratings of self-dissolution, a hallmark of psychedelic experience. Finally, using a recently developed metric, the functional excitatory-inhibitory ratio, we find that the DMT-induced criticality-shift in brain oscillations is toward subcritical regimes. These findings have major implications for the neuronal understanding of the self and psychedelics, as well as for the neurological basis of altered states of consciousness.

Neuroanatomical features across spatial scales contribute to functional specialization and individual differences in behavior across species. Among species with gyrencephalic brains, gyral crown height, which measures a key aspect of the morphology of cortical folding, may represent an anatomical characteristic that importantly shapes neural function. Nevertheless, little is known about the relationship between functional selectivity and gyral crowns-especially in clinical populations. Here, we investigated this relationship and found that the size and gyral crown height of the middle, but not posterior, face-selective region on the fusiform gyrus were decreased in individuals with developmental prosopagnosia (N = 22; 68% female; aged 25-62) compared with neurotypical controls (NTs; N = 25; 60% females; aged 21-55), and this difference was related to face perception. Additional analyses replicated the relationship between gyral crowns and face-selective region size in 1,053 NTs (55% females; aged 22-36). These results inform theoretical models of face processing while also providing a novel neuroanatomical feature contributing to the cortical infrastructure supporting face processing.

Sensorimotor and cognitive abilities undergo substantial changes throughout the human lifespan, but the corresponding changes in the functional properties of cortical networks remain poorly understood. This can be studied using temporal and spatial scales of functional magnetic resonance imaging (fMRI) signals, which provide a robust description of the topological structure and temporal dynamics of neural activity. For example, timescales of resting-state fMRI signals parsimoniously predict a significant amount of the individual variability in functional connectivity networks identified in adult human brains. In the present study, we quantified and compared temporal and spatial scales in resting-state fMRI data collected from 2,352 subjects of either sex between the ages of 5 and 100 in Developmental, Young Adult, and Aging datasets from the Human Connectome Project. For most cortical regions, we found that both temporal and spatial scales decreased with age throughout the lifespan, with the visual cortex and the limbic network consistently showing the largest and smallest scales, respectively. For some prefrontal regions, however, these two scales displayed non-monotonic trajectories and peaked around the same time during adolescence and decreased throughout the rest of the lifespan. We also found that cortical myelination increased monotonically throughout the lifespan, and its rate of change was significantly correlated with the changes in both temporal and spatial scales across different cortical regions in adulthood. These findings suggest that temporal and spatial scales in fMRI signals, as well as cortical myelination, are closely coordinated during both development and aging.

During passive listening, the brain maintains a hierarchy of predictive models to monitor the statistics of its surroundings. The automatic discovery of regular patterns has been associated with a gradual increase in sustained tonic magnetoencephalography (MEG)/electroencephalography activity, sourced in auditory, hippocampal, and frontal areas-reflecting evidence accumulation and establishment of a regularity model. Conversely, when a regular pattern is interrupted, the sustained activity drops-indicating disengagement from the model. However, how such models are established in and retrieved from memory and the conditions under which they are activated and interrupted remain underexplored. In this MEG experiment (N = 26 human participants; both sexes), we examined how neural responses related to model "establishment" and "interruption" are influenced by (1) the rate of stimulus presentation (tone presentation rate 20 vs 40 Hz) and (2) the novelty of the experienced acoustic structure (novel vs resumed regular pattern). The results show that (1) the dynamics of model interruption and establishment are independent of stimulus presentation rate, and that (2) model establishment occurred much faster when an experienced versus novel pattern was presented after pattern interruption, suggesting reactivation of the stored original model facilitated by the hippocampus. (3) Finally, sustained-response rises in response to pattern establishment and interruption were localized in auditory, hippocampal, and frontal sources, supporting top-down model information flow. These results unveil the temporal dynamics and neural network underlying the brain's construction and selection of predictive models to monitor changes in sensory statistics.