Biology subjects

Nara, S.

Publications and source records attributed to Nara, S..

12 recordsLinked to original sources

bioRxiv2026

Early EEG responses indicate liking for artworks presented in rapid visual streams

When we appreciate visual art, we often take our time: We visit museums or galleries and deliberately engage with artworks and their meaning. Yet, our liking might at least partly be shaped by incidental encoding of the artworks' visual features, a process initially independent from sustained engagement. Here, we show that liking for visual art can be predicted from rapid and automatic responses in the visual brain. We recorded EEG responses while participants viewed 999 artworks from the Vienna Art Picture System (VAPS), which features complex artworks that span different categories and art styles. Artworks were shown with a 300ms stimulus-onset-asynchrony (150ms on, 150 off), and participants responded to occasional target images. Using representational similarity analysis, we predicted the geometry of neural representations from the artworks' similarity in liking (based on ratings from a different group of observers), while simultaneously controlling for similarities in other properties (category, art style, valence, arousal, and familiarity). Crucially, neural responses emerging within the first 150ms were robustly connected to liking, even though the task did not afford any liking judgments. Strikingly, this early neural correlate of liking was also observed in a second experiment, in which we presented the same 999 artworks with a 50ms stimulus-onset-asynchrony. Our results show that even under ultra-fast presentation conditions, automatic neural responses rapidly indicate liking. While fully appreciating an artwork may still need deliberate and prolonged engagement, the perceptual basis of whether we like or dislike an artwork seems to be laid in a split second.

neuroscience↗

bioRxiv2026

Tactile pup loss and acoustic signal enhance selective maternal retrieval behavior in echolocating bats, Pipistrellus abramus

Pup retrieval is a critical maternal behavior ensuring pup survival. Its mechanisms have been studied mainly in rodents, where mothers tolerate brief pup separation. In contrast, in species for which even short separation is life-threatening, mothers maintain constant physical contact, reinforcing anti-separation behavior. Studying such species may uncover maternal strategies under survival-critical extremes. Among these species, echolocating bats provide an ideal model for acoustic-based decision-making, as they rely heavily on sound. In bats, pup isolation calls (ICs) are essential signals in mother-pup communication. To assess their motivation in retrieval based on ICs, we conducted behavioral experiments: (1) pup retrieval test, and (2) playback test using ICs from own vs. non-own pups. Each was conducted under three maternal conditions: holding (a) no-pup, (b) one-pup, and (c) two-pup, to assess tactile influence on maternal motivation. In pup retrieval tests, mothers showed selective responsiveness to their own pups, and it is decreased with their pup development. Playback tests showed that acoustic signals alone were sufficient to elicit maternal responses, and their latencies were negatively correlated to pup vocalization rates. These maternal responses were strongly suppressed under condition (c), but robustly expressed under conditions (a) and (b). These findings suggest that maternal motivation is context-dependent responsiveness, which is enhanced by tactile pup loss and ICs, providing insight into instinctive maternal behavior in mammals. Summary statementThis study demonstrates that in the Pipistrellus abramus, maternal motivation is context-dependent responsiveness, which is enhanced by tactile pup loss and vocalizations, providing insight into a flexible multimodal mechanism underlying instinctive maternal behavior.

animal behavior and cognition↗

bioRxiv2025

Platform of single-molecule enzyme activity-based liquid biopsy for detection of pancreatic adenocarcinoma at early stages

Liquid biopsy analyzes biomolecules in biofluids to provide critical information for the early detection of diseases and the development of more effective treatment strategies. Among these biomolecules, the functional states of proteins offer particularly valuable insights due to their direct correlation with phenotypic changes. However, current approaches for assessing protein function in liquid biopsies are often limited by low detection sensitivity. Here, we present a liquid biopsy platform that analyzes single-molecule protease/peptidase activity to detect pathological alterations in enzyme function in blood samples. The platform demonstrates potential for identifying patients with early-stage (stage I-II) pancreatic ductal adenocarcinoma (PDAC).

biochemistry↗

bioRxiv2025

Dynamic neural representations of scene beauty are relatively unaffected by stimulus timing and task

Understanding the neural correlates of aesthetic experiences in natural environments is a central question in neuroaesthetics. A previous EEG study (Kaiser, 2022) identified early and temporally sustained neural representations of visual scene beauty. These results were obtained with long presentation durations (1,450 ms) and with explicit beauty judgments, rendering it unclear how presentation time and task demands shape the neural correlates of scene beauty. In two EEG experiments, we replicated this study while varying presentation time and task. Experiment 1 tested whether reducing stimulus presentation time from 1,450 ms to 100 ms altered neural representations of beauty. Experiment 2 examined whether beauty-related representations prevailed when participants performed an orthogonal task instead of explicitly judging beauty. Representational similarity analysis revealed that beauty-related neural representations emerged early (within 150 - 200 ms post-stimulus) and were sustained over time, in line with previous findings. Critically, we found that neither reduced presentation time nor the absence of an explicit beauty judgment significantly altered beauty-related neural dynamics. These results suggest that the neural correlates of scene beauty are relatively robust to stimulus presentation and task regimes, providing a potential correlate of the spontaneous perception of beauty in natural environments.

neuroscience↗

bioRxiv2024

The functional anatomy of nociception: Effective Connectivity in Chronic Pain and Placebo Responders

There is growing recognition of cortical involvement in nociception. The present study is motivated by predictive coding formulations of pain perception that stress the importance of top-down and bottom-up information flow in the brain. It compares forward and backward effective connectivity - estimated from resting-state fMRI - between chronic osteoarthritic patients and healthy control subjects. Additionally, it assesses differences in effective connectivity between placebo responders and non-responders and asks whether these differences can be used to predict pain perception and placebo response. To assess hierarchical processing in nociception, we defined two primary cortical regions: primary somatosensory cortex (SSC) and posterior insula (PI) (primary interoceptive cortex) and lateral frontal pole (FP1), a terminal relay station of the pain processing pathways. The directed (effective) connectivity within and between these regions were estimated using spectral dynamic causal modeling (DCM). 56 osteoarthritis patients and 18 healthy controls were included in the analysis. Within the patient group, effective connectivity was compared between placebo responders and non-responders. In osteoarthritic patients, contra control group, forward connectivity from SSC to FP1 and from PI to FP1 was enhanced in the left hemisphere. Backward connections from FP1 to SSC were more inhibitory. Intrinsic (i.e., inhibitory recurrent or self-connectivity) of left FP1 increased. In placebo responders compared to non-responders, forward connections from bilateral SSC to PI, left SSC to FP1, left PI to left FP1 were more inhibitory. In addition, self-connections of bilateral PI and top-down connections from right FP1 to right SSC were disinhibited; whereas self-connections of right FP1 became increasingly inhibitory. We confirmed the robustness of these results in a leave-one-out cross-validation analysis of (out-of-sample) effect sizes. Overall, effective extrinsic and intrinsic effective connectivity among higher and lower cortical regions involved in pain processing emerges as a promising and quantifiable candidate marker of nociception and placebo response. The significance of these findings for clinical practice and neuroscience are discussed in relation to predictive processing accounts of placebo effects and chronic pain.

neuroscience↗

bioRxiv2023

Integrative processing in artificial and biological vision predicts the perceived beauty of natural images

Previous research indicates that the beauty of natural images is already determined during perceptual analysis. However, it is still largely unclear which perceptual computations give rise to the perception of beauty. Theories of processing fluency suggest that the ease of processing for an image determines its perceived beauty. Here, we tested whether perceived beauty is related to the amount of spatial integration across an image, a perceptual computation that reduces processing demands by aggregating image elements into more efficient representations of the whole. We hypothesized that higher degrees of integration reduce processing demands in the visual system and thereby predispose the perception of beauty. We quantified integrative processing in an artificial deep neural network model of vision: We compared activations between parts of the image and the whole image, where the degree of integration was determined by the amount of deviation between activations for the whole image and its constituent parts. This quantification of integration predicted the beauty ratings for natural images across four studies, which featured different stimuli and task demands. In a complementary fMRI study, we show that integrative processing in human visual cortex predicts perceived beauty in a similar way as in artificial neural networks. Together, our results establish integration as a computational principle that facilitates perceptual analysis and thereby mediates the perception of beauty.

neuroscience↗

bioRxiv2023

Language experience shapes predictive coding of rhythmic sound sequences

Perceptual systems heavily rely on prior knowledge and predictions to make sense of the environment. Predictions can originate from multiple sources of information, including contextual short-term priors, based on isolated temporal situations, and context-independent long-term priors, arising from extended exposure to statistical regularities. While the effects of short-term predictions on auditory perception have been well-documented, how long-term predictions shape early auditory processing is poorly understood. To address this, we recorded magnetoencephalography data from native speakers of two languages with different word orders (Spanish: functor-initial versus Basque: functor-final) listening to simple sequences of binary sounds alternating in duration with occasional omissions. We hypothesized that, together with contextual transition probabilities, the auditory system uses the characteristic prosodic cues (duration) associated with the native languages word order as an internal model to generate long-term predictions about incoming non-linguistic sounds. Consistent with our hypothesis, we found that the amplitude of the mismatch negativity elicited by sound omissions varied orthogonally depending on the speakers linguistic background and was most pronounced in the left auditory cortex. Importantly, listening to binary sounds alternating in pitch instead of duration did not yield group differences, confirming that the above results were driven by the hypothesized long-term "duration" prior. These findings show that experience with a given language can shape a fundamental aspect of human perception - the neural processing of rhythmic sounds - and provides direct evidence for a long-term predictive coding system in the auditory cortex that uses auditory schemes learned over a lifetime to process incoming sound sequences.

neuroscience↗

bioRxiv2023

Early language dissociation in the bilingual mind: Sensor-level MEG evidence

Is language selection in balanced bilinguals decodable from neural activity? Previous research employing various neuroimaging methods has not yielded a conclusive answer to this issue. However, direct brain stimulation studies in bilinguals have detected different brain regions related to language production in separate languages. In the present MEG study, we addressed this question in a group of proficient Spanish-Basque bilinguals (N=45), who performed two tasks (picture naming and word reading). They were asked to name the line drawing or read the word out loud, either in Basque or Spanish, if the ink turned from black to green after one second (randomly, in 10% of trials). Sensor-level evoked activity was similar and could not be differentiated for the two languages in either task. Crucially however, decoding analyses classified the language used in both tasks, starting [~]100 ms after stimulus onset. Searchlight analyses revealed that activity detected in the right occipital-temporal sensors contributed the most to language decoding in the picture naming task, while the left occipital-temporal sensors contributed the most to decoding in word reading. The cross-task decoding analysis highlighted robust generalization effects from the picture naming to the word reading task in a later time interval. The present findings bridge the gap between non-invasive and invasive experimental evidence on bilingual lexical processing and provide novel evidence about the role of the two hemispheres in activating each language for picture naming and word reading.

neuroscience↗

bioRxiv2022

The shh limb enhancer is activated in patterned limb regeneration but not in hypomorphic limb regeneration in Xenopus laevis

Xenopus young tadpoles regenerate a limb with the anteroposterior (AP) pattern, but metamorphosed froglets regenerate a hypomorphic limb after amputation. The key gene for AP patterning, shh, is expressed in a regenerating limb of the tadpole but not in that of the froglet. Genomic DNA in the shh limb-specific enhancer, MFCS1 (ZRS), is hypermethylated in froglets but hypomethylated in tadpoles: shh expression may be controlled by epigenetic regulation of MFCS1. Is MFCS1 specifically activated for regenerating the AP-patterned limb? We generated transgenic Xenopus laevis lines that visualize the MFCS1 enhancer activity with a GFP reporter. The transgenic tadpoles showed GFP expression in hoxd13- and shh-expressing domains of developing and regenerating limbs, whereas the froglets showed no GFP expression in the regenerating limbs despite having hoxd13 expression. Genome sequence analysis and co-transfection assays using cultured cells revealed that Hoxd13 can activate Xenopus MFCS1. These results suggest that MFCS1 activation correlates with regeneration of AP-patterned limbs and that re-activation of epigenetically inactivated MFCS1 would be crucial to confer the ability to non-regenerative animals for regenerating a properly patterned limb.

developmental biology↗

bioRxiv2022

Decoding Numeracy and Literacy in the Human Brain: Insights from MEG and MVPA

Numbers and letters are the fundamental building blocks of our everyday social interactions. Previous studies have focused on determining the cortical networks shaped by numeracy and literacy in the human brain, partially supporting the hypothesis of distinct neural circuits involved the processing of the two categories. In this study, we aim to investigate the temporal dynamics for number and letter processing. We present MEG data from two experiments (N=20 each). In the first experiment, single numbers, letter, and their respective false fonts (false numbers and false letters) were presented, whereas, in the second experiment, numbers, letters, and their respective false fonts were presented as a string of characters. We used multivariate pattern analysis techniques (time-resolved decoding and temporal generalization) testing the strong hypothesis that the neural mechanisms supporting letter and number processing can be logistically classified as categorically separate. Our results show a very early dissociation ([~]100 ms) between numbers, and letters when compared to false fonts. Number processing can be dissociated with similar accuracy when presented as isolated items or strings of characters, while letter processing shows dissociable classification accuracy for single items compared to strings. These findings reinforce the evidence indicating that early visual processing can be differently shaped by the experience with numbers and letters; this dissociation is stronger for strings compared to single items, thus showing that combinatorial mechanisms for numbers and letters could be categorically distinguished and influence early brain activity.

neuroscience↗

bioRxiv2021

Temporal Dynamics of Neural Processing of Facial Expressions and Emotions

Emotion processing has been a focus of research in psychology and neuroscience for some decades. While the evoked neural markers in human brain activations in response to different emotions have been reported, the temporal dynamics of emotion processing has received less attention. Differences in processing speeds, that depend on emotion type, have not been determined. Furthermore, behavioral studies have found that the right side of the human face expresses emotions more accurately than the left side. Therefore, accounting for both the content of the emotion and the visual angle of presentation from the perspective of the viewer, here we have investigated variability in the discrimination of happy and sad faces when the visual angle of presentation was Positive (right side of the face) compared to Negative (left side of the face). Furthermore, the temporal dynamics involved in processing happy and sad emotions have been compared. Regardless of visual angle, happy emotions were processed faster than sad emotions. However, the evoked response to sad emotions significantly increased in amplitude compared to that for happy emotions, when faces were presented at Positive visual angles only. Source reconstruction from sensor-level ERFs show localized activities in ventral and dorsal stream, including fusiform gyrus, lingual gyrus, putamen and Pre and Post central gyrus. Multivariate pattern analysis (MVPA) confirmed these findings - demonstrating successful decoding of happy and sad emotions only occurred when the facial expression was viewed from a positive visual angle, and that happy emotions were processed faster than sad emotions.

neuroscience↗

bioRxiv2020

Temporal uncertainty affects the visual processing of predicted stimulus properties

Predictive processing has been proposed as a fundamental cognitive mechanism to account for how the brain interacts with the external environment via its sensory systems. In vision, contextual information triggers predictions about the content ("what") of environmental stimuli to update an internal generative model of the surrounding world. However, visual information dynamically changes across time, and temporal predictability ("when") may influence the impact of internal predictions on visual processing. In this magnetoencephalography (MEG) study, we investigated how processing feature specific information ("what") is affected by temporal predictability ("when"). In line with previous findings, we observed suppression of evoked neural responses in the visual cortex for predictable stimuli. Interestingly, we found that temporal uncertainty increased expectation suppression. This suggests that in temporally uncertain scenarios the neurocognitive system invests less resources in integrating bottom-up information. Multivariate pattern analysis showed that predictable visual features could be decoded from neural responses. Temporal uncertainty did not affect decoding accuracy for early visual responses, with the feature specificity of early visual neural activity preserved across conditions. However, decoding accuracy was less sustained over time for temporally jittered than for isochronous predictable visual stimuli. These findings converge to suggest that the cognitive system processes visual features of temporally predictable stimuli in higher detail, while processing temporally uncertain stimuli may rely more heavily on abstract internal expectations.

neuroscience↗