Journal of Neuroscience最新文献

Macaque primary visual cortex (V1) exhibits exquisite columnar organization, while midlevel area V4 does not. Here we investigated the functional organization and representational bases of intervening area V2 in three macaques (one male, two females) with high-density Neuropixels recordings and a variety of visual stimuli-shape, texture, drifting grating, and translational motion patches. We observed dense clusters of similarly tuned neurons often spanning ∼500 µm, consistent with a columnar structure. In terms of representational bases, V2 responses were largely explained by stimulus features based on local image statistics: shape tuning is well-modeled by a linear combination of orientation filters, and direction selectivity is stronger with surface compared to object motion, in striking contrast to V4. Overall, our results support the progression from columns to sparse clusters as neuronal representations transform from encoding local features and feature conjunctions in V1/V2 to a high-dimensional object-based code in V4.Significance Statement By recording hundreds of neurons simultaneously across layers of macaque visual area V2, we show the first evidence of exquisite fine-scale functional clusters that encode higher-order shape, texture, and motion features, extending well beyond the classic orientation-selective columns seen in area V1. Comparative analyses with V4 further reveal distinct representational bases and organization patterns between adjacent cortical areas, demonstrating that columnar organization is preserved in early visual areas (V1 and V2) but is markedly attenuated in higher-order cortex such as V4.

Bidirectional interactions between sleep, seizures, and epilepsy remain incompletely understood. Evidence from animal models and people with focal epilepsy suggest that seizures may engage mechanisms of memory consolidation during post-ictal sleep to reinforce and strengthen synaptic connections within the pathological networks that generates seizures, termed seizure-related consolidation (SRC). Human studies of post-ictal sleep changes supportive of SRC, however, are limited by small sample size and restricted observations of post-ictal sleep. We investigated the interplay between seizures and sleep by analyzing sleep-wake and seizure catalogs derived from continuous local field potential (LFP) recordings in 11 people (6 males and 5 females) with drug-resistant focal epilepsy implanted with novel investigational devices and living in their natural environments. Our findings demonstrate that post-ictal rapid-eye-movement sleep duration is reduced, whereas slow-wave sleep duration, slow-wave LFP spectral power, and waveform slope are increased compared with inter-ictal nights without preceding seizures. The most significant changes localize to the epileptogenic networks generating the participants' habitual seizures. These results reveal parallels between SRC and physiological memory consolidation, providing novel insights into the potential role of post-ictal sleep in strengthening epileptic neural engrams and may have implications for targeted disruption of post-ictal sleep and SRC in focal epilepsy.

Our visual world consists of an immense number of unique objects and yet, we are easily able to identify, distinguish, and reason about the things we see within a few hundred milliseconds. Here, we used a large-scale and comprehensively sampled stimulus set and developed an analysis approach to capture how rich, multidimensional object representations unfold over time in the human brain. We modeled time-resolved MEG signals of four humans (two females and two males) viewing single presentations of tens of thousands of object images based on millions of behavioral judgments. Extracting behavior-derived object dimensions from similarity judgments, we developed a data-driven approach to guide our understanding of the neural representation of the object space and found that every dimension is reflected in the neural signal. Studying the temporal profiles for different object dimensions, we found that the time courses fell into two broad types, with either a distinct and early peak (∼125 ms) or a slow rise to a late peak (∼300 ms). Further, early effects were stable across participants, in contrast to later effects which showed more variability, suggesting that early peaks may carry stimulus-specific and later peaks more participant-specific information. Dimensions with early peaks appeared to be primarily visual dimensions and those with later peaks more conceptual, suggesting that conceptual representations are more variable across people. Together, these data provide a comprehensive account of how behavior-derived object properties unfold in the human brain and form the basis for the rich nature of object vision.

Neuronal network models have indicated that the so-called critical dynamics facilitate efficient information processing, while criticality disruptions were linked to neuropathology through excitation/inhibition (E/I) imbalances. However, there is limited empirical evidence for a relationship between critical brain dynamics and cognition in healthy children and adolescents. Here, we investigate how these dynamics relate to intelligence in a developing cohort. We recorded eyes-open resting EEG in 128 children (6-19 years, 72 female) and quantified near-critical dynamics in the alpha-band using functional excitation/inhibition ratio (fE/I) and in nonoscillatory activity using the 1/f aperiodic exponent of the power spectrum. We devised models relating intelligence to fE/I and 1/f exponent across seven Yeo7 functional brain networks ranked from lower-order sensorimotor to higher-order association networks. We observed significant correlations between fE/I and 1/f exponent and IQ in association cortices, in contrast to sensorimotor cortices. Children in the high-IQ group had fE/I ratios closer to the theoretical critical value of 1 in association cortices compared with the low-IQ group. The association-sensorimotor axis rank moderated the associations between 1/f exponent and IQ, these associations decreasing on a gradient across the hierarchy of the Yeo7 networks. Age and rank moderated the fE/I-IQ association, with the association-sensorimotor effect size gradient most visible in adolescents. Together, the results suggest that individual variation in criticality-sensitive biomarkers in association networks may be linked to IQ differences in an age-dependent manner, consistent with the hypothesis that developmental modulation of critical dynamics across the cortical hierarchy may support more efficient cognitive processing.

Processing ordinality, i.e., the rank of an item in a series such as 1st, 2nd, 3rd, etc., is a fundamental skill shared by humans and animals. While humans often use symbolic sequences like numbers or letters, ordinality does not depend on language or symbols. Across species, ordinality plays a critical role in behaviors such as decision-making, foraging, and social organization. We hypothesize that ordinality perception is supported by neuronal tuning, i.e., neurons selectively responsive to specific ranks. Using ultrahigh-field 7 T fMRI and population receptive field (pRF) modeling in human participants (both female and male), we identified neural populations in parietal and premotor cortices that are tuned to nonsymbolic ordinal positions. Comparable with other sensory domains, tuning width increased with preferred ordinal rank, suggesting reduced precision and potentially lower perceptual accuracy for higher ranks. Additionally, pRF measurements revealed that cortical territory devoted to higher ordinalities decreased with rank, reinforcing that neural precision is greatest for early positions (e.g., 1st and 2nd) and declines with rank. These responses did not generalize to symbolic ordinality. Similar tuning to nonsymbolic ordinality emerged spontaneously in hierarchical convolutional neural networks trained on visual tasks. Together, these results suggest that the tuning properties of these neuronal populations support nonsymbolic ordinality perception and may reflect an inherent feature of neural processing.

In adulthood, the regenerative capacity of the injured brain circuit is poor, thereby preventing functional restoration. Rehabilitative physical exercise is a promising approach for enhancing the behavioral recovery after neuronal injury to both the central and peripheral nervous systems. The metabolic energy sensor AMPK acts as a mediator for the exercise benefit in Caenorhabditis elegans axon regeneration. However, the mechanistic understanding of upstream and downstream components of AMPK signaling in the physical exercise-mediated enhancement of axon regeneration is still unclear. Here, we addressed this question by combining swimming exercise with laser axotomy of C. elegans posterior lateral microtubule (PLM) neurons. Using a genetically encoded ATP sensor iATPsnFR1.0, we observed that immediately after swimming exercise, ATP level is decreased both in neuron and muscle. Further, we found that AICAR-mediated AMPK activation is sufficient to promote axon regeneration and functional recovery. The PAR-4/Liver kinase B1 acts upstream of AMPK to improve functional recovery through swimming exercise. We also found that the transcriptional regulators DAF-16 and MDT-15 mediate the beneficial effects of swimming by acting downstream of AMPK. MDT-15 functions within neuron to mediate the benefit of AMPK activation, whereas DAF-16 acts both in neuron and muscle to promote functional restoration. Additionally, we demonstrated that swimming exercise induces nuclear localization of DAF-16 in an AMPK-dependent manner. Our results showed that neuronal and non-neuronal arms of AMPK signaling play an integrative role in response to physical exercise to promote functional recovery after axon injury.