Aversive societal conditions explain differences in “dark” personality across countries and US states Humans differ in their levels of aversive (“dark”) personality traits such as egoism or psychopathy. Building upon theories suggesting that socioecological factors coshape the development of personality traits, it can be predicted that prior aversive societal conditions (ASC) (herein assessed via corruption, inequality, poverty, and violence) explain individuals’ levels of aversive personality (assessed via the Dark Factor of Personality, the common core underlying all aversive traits). Results considering individuals from 183 countries (N = 1,791,542) and 50 US states (N = 144,576) support the idea that ASC coshape individuals’ levels of aversive personality.
Intensive task-switching training and single-task training differentially affect behavioral and neural manifestations of cognitive control in children The ability to flexibly switch between tasks develops during childhood. Children’s task-switching performance improves with practice, but the underlying processes remain unclear. We used functional magnetic resonance imaging to examine how 9 weeks of task-switching training affect performance and task-related activation and functional connectivity. Children (8–11 years) were assigned to one of three groups: intensive task switching (SW; n = 72), intensive single tasking (SI; n = 74), and passive control (n = 41). While mixing costs decreased in both training groups initially, only the SW group maintained these training-related improvements at the end of training. Activation in the dorsolateral prefrontal cortex decreased with training, but again only the SW group maintained these activation decreases at the end of training. Condition-specific connectivity increases with task switching became less pronounced with training, especially in the SI group. Lower costs of task switching along with decreased task-related activations suggest increased processing efficiency in frontoparietal regions with training. Intensive task-switching training was associated with sustained changes, possibly facilitated by a greater mismatch between processing supplies and environmental demands. Our findings suggest that experience-dependent changes with intensive task-switching training do not mirror maturational processes but rather facilitate performance via more efficient task processing.
Activity-dependent development of the body’s touch receptors We report a role for activity in the development of the primary sensory neurons that detect touch. Genetic deletion of Piezo2, the principal mechanosensitive ion channel in somatosensory neurons, caused profound changes in the formation of mechanosensory end-organ structures. Peripheral-nervous-system-specific deletion of the voltage-gated sodium channel Nav1.6 (Scn8a), which resulted in altered electrophysiological responses to mechanical stimuli, also disrupted somatosensory neuron morphologies, supporting a role for neuronal activity in end-organ formation. Single-cell RNA sequencing of Piezo2 mutants revealed changes in gene expression in sensory neurons activated by light mechanical forces, whereas other neuronal classes were minimally affected, and genetic deletion of Piezo2-dependent genes partially reproduced the defects in mechanosensory neuron structures observed in Piezo2 mutants. These findings indicate that mechanically evoked neuronal activity acts early in life to shape the maturation of mechanosensory end-organs that underlie our sense of gentle touch.
Doubling-Back Aversion: A Reluctance to Make Progress by Undoing It Four studies (N = 2,524 U.S.-based adults recruited from the University of California, Berkeley, or Amazon Mechanical Turk) provide support for doubling-back aversion, a reluctance to pursue more efficient means to a goal when they entail undoing progress already made. These effects emerged in diverse contexts, both as participants physically navigated a virtual-reality world and as they completed different performance tasks. Doubling back was decomposed into two components: the deletion of progress already made and the addition to the proportion of a task that was left to complete. Each contributed independently to doubling-back aversion. These effects were robustly explained by shifts in subjective construals of both one’s past and future efforts that would result from doubling back, not by changes in perceptions of the relative length of different routes to an end state. Participants’ aversion to feeling their past efforts were a waste encouraged them to pursue less efficient means. We end by discussing how doubling-back aversion is distinct from established phenomena (e.g., the sunk-cost fallacy).
A conserved code for anatomy: Neurons throughout the brain embed robust signatures of their anatomical location into spike trains Neurons in the brain are known to encode diverse information through their spiking activity, primarily reflecting external stimuli and internal states. However, whether individual neurons also embed information about their own anatomical location within their spike patterns remains largely unexplored. Here, we show that machine learning models can predict a neuron’s anatomical location across multiple brain regions and structures based solely on its spiking activity. Analyzing high-density recordings from thousands of neurons in awake, behaving mice, we demonstrate that anatomical location can be reliably decoded from neuronal activity across various stimulus conditions, including drifting gratings, naturalistic movies, and spontaneous activity. Crucially, anatomical signatures generalize across animals and even across different research laboratories, suggesting a fundamental principle of neural organization. Examination of trained classifiers reveals that anatomical information is enriched in specific interspike intervals as well as responses to stimuli. Within the visual isocortex, anatomical embedding is robust at the level of layers and primary versus secondary but does not robustly separate individual secondary structures. In contrast, structures within the hippocampus and thalamus are robustly separable based on their spike patterns. Our findings reveal a generalizable dimension of the neural code, where anatomical information is multiplexed with the encoding of external stimuli and internal states. This discovery provides new insights into the relationship between brain structure and function, with broad implications for neurodevelopment, multimodal integration, and the interpretation of large-scale neuronal recordings. Computational approximations of anatomy have potential to support in-vivo electrode localization.
State-dependent associative plasticity highlights function-specific premotor-motor pathways crucial for arbitrary visuomotor mapping Arbitrary visuomotor mapping (AVMM) showcases the brain’s ability to link sensory inputs with actions. The ventral premotor cortex (PMv) is proposed as central to sensorimotor transformations, relaying descending motor commands through the primary motor cortex (M1). However, direct evidence of this pathway’s involvement in AVMM remains elusive. In four experiments, we used cortico-cortical paired associative stimulation (ccPAS) to enhance (ccPASPMv-M1) or inhibit (ccPASM1-PMv) PMv-to-M1 connectivity via Hebbian plasticity. Leveraging state-dependent properties of transcranial magnetic stimulation, we targeted function-specific visuomotor neurons within the pathway, testing their physiological/behavioral relevance to AVMM. State-dependent ccPASPMv-M1, applied during motor responses to target visual cues, enhanced neurophysiological and behavioral indices of AVMM, while ccPASM1-PMv had an opposite influence, with the effects being more pronounced for target relative to control visual cues. These results highlight the plasticity and causal role of spatially overlapping but functionally specific neural populations within the PMv-M1 pathway in AVMM and suggest state-dependent ccPAS as a tool for targeted modulation of visuomotor pathways.
Age-Related Differences in Neural Correlates of Auditory Spatial Change Detection in Real and Virtual Environments Although virtual environments are increasingly used in research, their ecological validity in simulating real-life scenarios, for example, to investigate cognitive changes in aging populations, remains relatively unexplored. This study aims to evaluate the validity of a virtual environment for investigating auditory spatial change detection in younger and older adults. This evaluation was performed by comparing behavioral and neurophysiological responses between real and virtual environments. Participants completed an auditory change detection task, identifying sound source position changes relative to a reference position. In the real environment, sounds were presented through physical loudspeakers in a reverberant room. In the virtual environment, stimuli were delivered through headphones, accompanied by a head-mounted display showing a visual replica of the room. Participants showed higher accuracy for azimuth than for distance changes, regardless of age or environment, emphasizing humans’ larger sensitivity to lateralized sounds. Event-related potentials were mostly consistent across environments, with significantly higher N1 and P2 amplitudes in older compared with younger adults. Mismatch negativity was reduced in older adults, and both reduced and delayed in the virtual environment. The P3b showed larger amplitudes and shorter latencies for azimuth changes, reflecting greater salience of directional cues, whereas responses in the virtual environment were slightly diminished, especially among older adults. Bayesian analyses validated the observed effects. Results support virtual environments as reliable tools for exploring spatial perception and underlying neural and behavioral processes in realistic contexts. Furthermore, differences in the processing of spatial changes in azimuth and distance, as well as age-related effects, could be highlighted.
Sequence diversity and encoded enzymatic differences of monocistronic L1 ORF2 mRNA variants in the aged normal and Alzheimer’s disease brain Reverse transcriptase (RT) activity in the human brain has been inferred through somatic retroinsertion/retrotransposition events, however actual endogenous enzymatic activities and sources remain unclear. L1 (LINE-1) retrotransposons bicistronically express ORF2, containing RT and endonuclease (EN) domains, and RNA binding protein ORF1, together enabling L1 retrotransposition and contributing to somatic genomic mosaicism (SGM). Here, we assessed endogenous RT activities and L1 mRNA diversity from cerebral cortical samples of 31 Alzheimer’s disease (AD) and non-diseased (ND) brains (both sexes) using enzymatic functional assays, targeted PacBio HiFi long-read sequencing, and quantitative spatial transcriptomics. Expected bicistronic, full-length L1 transcripts were absent from most samples, constituting <0.01% of L1 sequences, of which >80% were non-coding. Monocistronic ORF1 and ORF2 transcripts were identified across all samples, consistent with quantitative spatial transcriptomics that identified discordant ORF2 and ORF1 expression in neurons. All brains had RT activity, with AD samples showing less activity, consistent with neuronal loss of terminal AD vs. aged ND donors. Brain RT activity was higher in grey matter and correlated with increased neuronal ORF2 expression, further supporting neuronal contributions. Remarkably, >550 protein-encoding, polyA+ ORF2 sequence variants were identified, over 2x more than identified in the human reference genome (hg38). Experimental overexpression of full-length and truncated ORF2 variants revealed ∼50-fold RT and ∼1.3-fold EN activity ranges, supporting endogenous functional capacity of monocistronic ORF2 variants in the human brain. The vast sequence diversity of monocistronic ORF2 mRNAs could underlie functional differences in RT-mediated somatic gene recombination/retroinsertion and resulting genomic mosaicism in the normal and diseased brain.