Biology subjects

Lanfranco, R. C.

Publications and source records attributed to Lanfranco, R. C..

8 recordsLinked to original sources

bioRxiv2026

Conscious and unconscious eye contact at the limits of vision

Eye contact is one of the most potent social signals, but it remains unclear how little visual input is sufficient to register direct gaze, and whether such registration requires conscious awareness. Here, we used a custom tachistoscope to present faces for only 1-5 ms, asking whether gaze direction can shape perception at the very limits of vision. Direct-gaze faces required less visual input to localise than averted-gaze faces and produced higher localisation sensitivity from 3 ms onwards. Crucially, this advantage emerged before participants could explicitly categorise gaze direction, and before perceptual awareness ratings showed metacognitive access to the information driving localisation, both of which appeared only at 4-5 ms. Information-theoretic analyses confirmed that localisation responses carried stimulus-location information before explicit reports and awareness ratings became informative. A second experiment showed that the earliest eye-contact advantage depended mainly on low spatial frequencies, indicating a role for coarse visual information. Finally, autistic traits were associated with a reduced localisation advantage for direct gaze. These findings show that eye contact can influence perceptual processing within just a few milliseconds, with less visual stimulation than is required for conscious access to gaze direction.

neuroscience↗

bioRxiv2026

Beta oscillations support somatosensory temporal integration for body ownership

The sense of body ownership, the perceptual experience of what belongs to ones body, relies on the integration of self-related signals across multiple sensory modalities. Alpha oscillations modulate the temporal resolution of visuotactile integration for body ownership by constraining how visual and tactile signals from the body are temporally combined or segregated. However, body ownership can be supported and modulated in the absence of vision, for example during self-touch, raising the question of whether the same alpha-based temporal mechanism supports purely somatosensory integration. Here, we show that individual beta frequency (IBF), rather than alpha, predicts the temporal integration of tactile signals between the two hands in a somatic rubber hand illusion self-touch paradigm. IBF predicted the temporal window within which two tactile stimuli were judged as simultaneous and within which illusory self-touch body ownership was experienced. Moreover, while individual alpha frequency did not contribute to this purely somatosensory integration, IBF also did not predict the temporal resolution of visuotactile integration when visual body-related inputs were available. Together, these findings suggest a double dissociation in which frequency-specific oscillatory processes reflect the temporal integration of bodily signals in a modality-dependent manner: beta frequency emerges as the key correlate of somatosensory integration during self-touch, whereas alpha frequency governs visuotactile integration when vision is available.

neuroscience↗

bioRxiv2025

Neural information sharing across the orienting attentional network predicts intelligence in children

Efficient brain functioning is often defined as the ability to achieve high performance with minimal cognitive resources. This study investigated the relationship between intelligence and attentional network efficiency in school-aged children, using electroencephalography (EEG) during the Attention Network Test (ANT). Participants were 38 children aged 11-14 years, recruited from schools in the Maule Region of Chile. Attentional network efficiency was assessed through event-related potentials (ERPs), midfrontal theta power as an index of conflict processing, and weighted Symbolic Mutual Information (wSMI) to quantify large-scale, nonlinear information sharing. Higher full-scale IQ scores were specifically associated with reduced wSMI within the orienting network, suggesting greater neural efficiency through less widespread information exchange between dorsal frontoparietal nodes. No significant associations were found between IQ and theta-band power during conflict processing. These findings provide novel evidence linking intelligence in childhood to network-level neural efficiency in attentional orienting, supporting the view that individual differences in cognitive ability reflect not only localized neural activity but also the efficiency of information integration within task-relevant networks.

neuroscience↗

bioRxiv2025

Parietal alpha frequency shapes own-body perception by modulating the temporal integration of bodily signals

An influential proposal in the field of cognitive neuroscience suggests that alpha-frequency brain oscillations constrain the temporal sampling of external sensory signals, shaping the temporal binding window (TBW)--the interval during which sensory signals are integrated. However, whether alpha frequency modulates the integration of self-related sensory signals and the perception of the body as ones own (body ownership) remains unknown. Here, we demonstrate that individual alpha frequency (IAF) from the parietal cortex predicted TBWs and perceptual sensitivities in body ownership and visuotactile simultaneity judgment tasks, with faster frequencies narrowing TBWs and increasing sensitivities, and vice versa. Modulating IAF through brain stimulation altered TBWs and sensitivities, establishing a causal relationship. Computational modeling linked IAF to uncertainty in asynchrony information within the causal inference process, providing a mechanism. These findings demonstrate that parietal alpha frequency shapes the sense of body ownership by modulating the temporal integration of bodily sensory signals.

neuroscience↗

bioRxiv2023

Slow-wave brain connectivity predicts executive functioning and group belonging in socially vulnerable individuals

Important efforts have been made to describe the neural and cognitive features of healthy and clinical populations. However, the neural and cognitive features of socially vulnerable individuals remain largely unexplored, despite their proneness to developing neurocognitive disorders. Socially vulnerable individuals can be characterised as socially deprived, having a low socioeconomic status, suffering from chronic social stress, and exhibiting poor social adaptation. While it is known that such individuals are likely to perform worse than their peers on executive function tasks, studies on healthy but socially vulnerable groups are lacking. In the current study, we explore whether neural power and connectivity signatures can characterise executive function performance in healthy but socially vulnerable individuals, shedding light on the impairing effects that chronic stress and social disadvantages have on cognition. We measured resting-state electroencephalography and executive functioning in 38 socially vulnerable participants and 38 matched control participants. Our findings indicate that while neural power was uninformative, lower delta and theta phase synchrony are associated with worse executive function performance in all participants, whereas delta phase synchrony is higher in the socially vulnerable group compared to the control group. Finally, we found that delta phase synchrony and years of schooling are the best predictors for belonging to the socially vulnerable group. Overall, these findings suggest that exposure to chronic stress due to socioeconomic factors and a lack of education are associated with changes in slow-wave neural connectivity and executive functioning.

neuroscience↗

bioRxiv2021

Minimal required exposures reveal the primacy of awareness in human face perception

Human vision can detect a single photon, but the minimal exposure required to extract meaning from stimulation remains unknown. This requirement cannot be cha racterised by stimulus energy, because the system is differentially sensitive to attributes defined by configuration rather than physical amplitude. Determining minimal exposure durations required for processing various stimulus attributes can thus reveal the systems priorities. Using a tachistoscope enabling arbitrarily brief displays, we established minimal durations for processing human faces, a stimulus category whose perception is associated with several well-characterised behavioural and neural markers. Neural and psychophysical measures showed a sequence of distinct minimal exposures for stimulation detection, object-level detection, face-specific processing, and emotion-specific processing. Resolving ongoing debates, face orientation affected minimal exposure but emotional expression did not. Awareness emerged with detection, showing no evidence of subliminal perception. These findings inform theories of visual processing and awareness, elucidating the information to which the visual system is attuned.

neuroscience↗

bioRxiv2021

Hypnotic visual hallucination induces greater lateralised brain activity than visual imagery

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.

neuroscience↗

bioRxiv2019

In your phase! Neural phase synchronization underlies visual imagery of faces

Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of "seeing with the minds eye". In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli have not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.

neuroscience↗