Aesthetic preference for art emerges from a weighted integration over hierarchically structured visual features in the brain, bioRxiv, 2020-02-10
AbstractIt is an open question whether preferences for visual art can be lawfully predicted from the basic constituent elements of a visual image. Moreover, little is known about how such preferences are actually constructed in the brain. Here we developed and tested a computational framework to gain an understanding of how the human brain constructs aesthetic value. We show that it is possible to explain human preferences for a piece of art based on an analysis of features present in the image. This was achieved by analyzing the visual properties of drawings and photographs by multiple means, ranging from image statistics extracted by computer vision tools, subjective human ratings about attributes, to a deep convolutional neural network. Crucially, it is possible to predict subjective value ratings not only within but also across individuals, speaking to the possibility that much of the variance in human visual preference is shared across individuals. Neuroimaging data revealed that preference computations occur in the brain by means of a graded hierarchical representation of lower and higher level features in the visual system. These features are in turn integrated to compute an overall subjective preference in the parietal and prefrontal cortex. Our findings suggest that rather than being idiosyncratic, human preferences for art can be explained at least in part as a product of a systematic neural integration over underlying visual features of an image. This work not only advances our understanding of the brain-wide computations underlying value construction but also brings new mechanistic insights to the study of visual aesthetics and art appreciation.
biorxiv neuroscience 0-100-users 2020A comprehensive atlas of white matter tracts in the chimpanzee, bioRxiv, 2020-01-26
AbstractChimpanzees (Pan troglodytes) are, along with bonobos, humans’ closest living relatives. The advent of diffusion tractography in recent years has allowed a resurgence of comparative neuroanatomical studies in humans and other primate species. Here, we offer, in comparative perspective, the first chimpanzee white matter atlas, coupled with surface projection maps of these major white matter tracts, constructed from in vivo chimpanzee diffusion-weighted scans. Comparative white matter atlases provide a useful tool for identifying neuroanatomical differences and similarities between humans and other primate species. Until now, comprehensive fascicular atlases have been created for humans (Homo sapiens), rhesus macaques (Macaca mulatta), and several other nonhuman primate species, but never in a nonhuman ape. Information on chimpanzee neuroanatomy is essential for understanding the anatomical specializations of white matter organization that are unique to the human lineage.
biorxiv neuroscience 0-100-users 2020Connectomics analysis reveals first, second, and third order thermosensory and hygrosensory neurons in the adult Drosophila brain, bioRxiv, 2020-01-21
SUMMARYAnimals exhibit innate and learned preferences for temperature and humidity – conditions critical for their survival and reproduction. Here, we leveraged a whole adult brain electron microscopy volume to study the circuitry associated with antennal thermosensory and hygrosensory neurons, which target specific ventroposterior (VP) glomeruli in the Drosophila melanogaster antennal lobe. We have identified two new VP glomeruli, in addition to the five known ones, and the projection neurons (VP PNs) that relay VP information to higher brain centres, including the mushroom body and lateral horn, seats of learned and innate olfactory behaviours, respectively. Focussing on the mushroom body lateral accessory calyx (lACA), a known thermosensory neuropil, we present a comprehensive connectome by reconstructing neurons downstream of heating- and cooling-responsive VP PNs. We find that a few lACA-associated mushroom body intrinsic neurons (Kenyon cells) solely receive thermosensory inputs, while most receive additional olfactory and thermo- or hygrosensory PN inputs in the main calyx. Unexpectedly, we find several classes of lACA-associated neurons that form a local network with outputs to other brain neuropils, suggesting that the lACA serves as a general hub for thermosensory circuitry. For example, we find DN1 pacemaker neurons that link the lACA to the accessory medulla, likely mediating temperature-based entrainment of the circadian clock. Finally, we survey strongly connected downstream partners of VP PNs across the protocerebrum; these include a descending neuron that receives input mainly from dry-responsive VP PNs, meaning that just two synapses might separate hygrosensory inputs from motor neurons in the nerve cord. (249)HIGHLIGHTS<jatslist list-type=bullet><jatslist-item>Two novel thermohygrosensory glomeruli in the fly antennal lobe<jatslist-item><jatslist-item>First complete set of thermosensory and hygrosensory projection neurons<jatslist-item><jatslist-item>First connectome for a thermosensory centre, the lateral accessory calyx<jatslist-item><jatslist-item>Novel third order neurons, including a link to the circadian clock<jatslist-item>
biorxiv neuroscience 0-100-users 2020AAV Ablates Neurogenesis in the Adult Murine Hippocampus, bioRxiv, 2020-01-20
ABSTRACTRecombinant adeno-associated virus (rAAV) has been widely used as a viral vector across mammalian biology and has been shown to be safe and effective in human gene therapy. We demonstrate that neural progenitor cells (NPCs) and immature dentate granule cells (DGCs) within the adult murine hippocampus are particularly sensitive to rAAV-induced cell death. Cell loss is dose dependent and nearly complete at experimentally relevant viral titers. rAAV-induced cell death is rapid and persistent, with loss of BrdU-labeled cells within 18 hours post-injection and no evidence of recovery of adult neurogenesis at 3 months post-injection. The remaining mature DGCs appear hyperactive 4 weeks post-injection based on immediate early gene expression, consistent with previous studies investigating the effects of attenuating adult neurogenesis. In vitro application of AAV or electroporation of AAV2 inverted terminal repeats (ITRs) is sufficient to induce cell death. Efficient transduction of the dentate gyrus (DG)—without ablating adult neurogenesis—can be achieved by injection of rAAV2-retro serotyped virus into CA3. rAAV2-retro results in efficient retrograde labeling of mature DGCs and permits in vivo 2-photon calcium imaging of dentate activity while leaving adult neurogenesis intact. These findings expand on recent reports implicating rAAV-linked toxicity in stem cells and other cell types and suggest that future work using rAAV as an experimental tool in the DG and as a gene therapy for diseases of the central nervous system (CNS) should be carefully evaluated.
biorxiv neuroscience 100-200-users 2020A standardized and reproducible method to measure decision-making in mice, bioRxiv, 2020-01-18
AbstractProgress in neuroscience is hindered by poor reproducibility of mouse behavior. Here we show that in a visual decision making task, reproducibility can be achieved by automating the training protocol and by standardizing experimental hardware, software, and procedures. We trained 101 mice in this task across seven laboratories at six different research institutions in three countries, and obtained 3 million mouse choices. In trained mice, variability in behavior between labs was indistinguishable from variability within labs. Psychometric curves showed no significant differences in visual threshold, bias, or lapse rates across labs. Moreover, mice across laboratories adopted similar strategies when stimulus location had asymmetrical probability that changed over time. We provide detailed instructions and open-source tools to set up and implement our method in other laboratories. These results establish a new standard for reproducibility of rodent behavior and provide accessible tools for the study of decision making in mice.
biorxiv neuroscience 200-500-users 2020Distinguishing the neural correlates of perceptual awareness and post-perceptual processing, bioRxiv, 2020-01-17
AbstractTo identify the neural correlates of perceptual awareness, researchers often compare the differences in neural activation between conditions in which an observer is or is not aware of a target stimulus. While intuitive, this approach often contains a critical limitation In order to link brain activity with perceptual awareness, observers traditionally report the contents of their perceptual experience. However, relying on observers’ reports is problematic because it makes it difficult to know if the neural responses being measured are associated with conscious perception per se or with post-perceptual processes involved in the reporting task (i.e., working memory, decision-making, etc.). To address this issue, we combined a standard visual masking paradigm with a recently developed “no-report” paradigm. In the visual masking paradigm, observers saw images of animals and objects that were visible or invisible depending on their proximity to masks. Meanwhile, on half of the trials, observers reported the contents of their perceptual experience (i.e., report condition), while on the other half of trials they refrained from reporting about their experiences (i.e., no-report condition). We used electroencephalography (EEG) to examine how visibility interacts with reporting by measuring the P3b event related potential (ERP), one of the proposed canonical “signatures” of conscious processing. Overall, we found a robust P3b in the report condition, but no P3b whatsoever in the no-report condition. This finding suggests that the P3b itself is not a neural signature of conscious processing and highlights the importance of carefully distinguishing the neural correlates of perceptual awareness from post-perceptual processing.Significance statementWhat are the neural signatures that differentiate conscious and unconscious processing in the brain? Perhaps the most well-established candidate signature is the P3b event-related potential (ERP), a late slow wave that appears when observers are aware of a stimulus, but disappears when a stimulus fails to reach awareness. Here, however, we found that the P3b does not track what observers are perceiving but instead tracks what observers are reporting. When observers are aware of simple visual stimuli, the P3b is nowhere to be found unless observers are reporting the contents of their experience. These results challenge the well-established notion of the P3b as a neural marker of awareness and highlight the need for new approaches to the neuroscience of consciousness.
biorxiv neuroscience 0-100-users 2020