Biology subjects

Rastelli, C.

Publications and source records attributed to Rastelli, C..

6 recordsLinked to original sources

bioRxiv2025

Robust spatial hearing beyond primary interaural cues in humans over deep neural networks

Spatial hearing allows humans to localize sound sources in the azimuth plane using interaural time (ITD) and level (ILD) differences, but the contribution of additional auditory features remains unclear. To investigate this, we measured human localization performance with natural and artificial stimuli that selectively included or excluded ITD and ILD as primary interaural cues. As expected, human listeners relied synergistically on ITD and ILD for accurate azimuth localization. Moreover, even when both primary cues were absent, localization performance remained above chance level. We compared human performance with state-of-the-art deep neural networks (DNN) optimized for sound localization to investigate possible computational mechanisms underlying this robust performance. In contrast to humans, DNNs demonstrated high accuracy only for stimuli that resembled their training regime but failed when primary interaural cues were absent. This human-DNN misalignment highlights a fundamental distinction in sensory processing strategies, potentially arising from the simplicity bias inherent in DNN training, with human reliance on a wider range of auditory features likely reflecting evolutionary pressures favoring adaptability across diverse acoustic environments. Together, our results demonstrate the robustness of human spatial hearing beyond primary interaural cues and point to promising directions for advancing artificial systems and informing clinical applications, such as cochlear implants and auditory prosthetics.

animal behavior and cognition↗

bioRxiv2025

Neural signatures of predictive coding underlying the acquisition of incidental sensory associations

A longstanding question in cognitive science is whether the human brain learns sensory regularities that are irrelevant to ongoing behavior, a phenomenon known as incidental associative learning. Here, we provide evidence at the single subject level that humans indeed acquired such incidental associations and reveal their neural signatures by combining Electroencephalography (EEG), multivariate decoding and computational modeling. We found robust encoding of incidental predictions and prediction errors underlying associative learning, consistent with predictive coding theories. Prediction errors were modulated by epistemic uncertainty, incidental associations persisted in memory over days and generalized beyond stimulus-stimulus pairings to encompass broader sensory events, including the absence of stimulation. Together, our results challenge traditional assumptions that associative learning requires behavioral relevance or physical co-occurrence and point to uncertainty minimization about environmental state transitions as a general objective of brain function. This intrinsic drive may reflect a fundamental computational principle supporting the formation of internal predictive models that guide perception, learning, and adaptive behavior.

neuroscience↗

bioRxiv2024

Immersive exposure to simulated visual hallucinations modulates high-level human cognition

Understanding altered states of consciousness induced by psychedelic drugs is crucial for advancing our knowledge of conscious perception and developing clinical applications for psychiatric conditions. Recently, technological advances in virtual reality (VR) headsets and deep neural network for generative computer vision have enabled the controlled, immersive simulation of visual hallucinations. Although there is some evidence that simulated visual hallucinations increase cognitive flexibility, comprehensive experimental data on how this artificially altered perceptual phenomenology affects high-level human cognition is lacking. We addressed this gap by measuring a wide range of behavioral tasks in human participants after the exposure to VR immersive panoramic (360{degrees}) videos and their psychedelic counterparts generated by the DeepDream algorithm. Participants exhibited reduced task-switching costs after simulated psychedelic exposure compared to naturalistic exposure when instructed to invert the stimulus-response mapping, consistent with increased cognitive flexibility. No significant differences were observed between naturalistic and simulated psychedelic exposure in linguistic association tasks at word and sentence levels. Crucially, we found that visually grounded high-level cognitive processes were modulated by exposure to simulated hallucinations, as evidenced by participants drawing performance. These findings reveal how altering perceptual phenomenology through simulated visual hallucinations significantly modulates high-level human cognition. Our results provide insights into the interdependence of bottom-up and top-down cognitive processes and encourage further investigation into the effects of artificial psychedelic experiences on human cognition. This research may offer valuable insights into altered states of consciousness without pharmacological intervention, potentially informing both basic neuroscience and clinical applications.

animal behavior and cognition↗

bioRxiv2024

Neural dynamics of semantic control underlying generative storytelling

Storytelling has been pivotal for the transmission of knowledge and cultural norms across human history. A crucial process underlying the generation of narratives is the exertion of cognitive control on the semantic representations stored in memory, a phenomenon referred as semantic control. Despite the extensive literature investigating the neural mechanisms of semantic control in generative language tasks, little effort has been done towards storytelling under naturalistic conditions. Here, we probed human participants to generate stories in response to a set of instructions which triggered a narrative that was either appropriate (ordinary), novel (random), or balanced (creative), while recording functional magnetic resonance imaging (fMRI) signal. By leveraging deep language models, we demonstrated how participants ideally balanced the level of semantic control during story generation. At the neural level, creative stories were differentiated by a multivariate pattern of neural activity in frontal cortices compared to ordinary ones and in fronto-temporo-parietal cortices with respect to randomly generated stories. Crucially, similar brain regions were also encoding the features that distinguished the stories behaviourally. Moreover, we decomposed the neural dynamics into connectome harmonic modes and found specific spatial frequency patterns underlying the modulation of semantic control during story generation. Finally, we found different functional coupling within and between the default mode, salience and control networks when contrasting creative stories with their controls. Together, our findings highlight the neural mechanisms underlying the regulation of semantic exploration during narrative ideation and contribute to a deeper understanding of the neural dynamics underpinning the role of semantic control in generative storytelling.

neuroscience↗

bioRxiv2024

Statistical learning of incidental perceptual regularities induces sensory conditioned cortical responses

Statistical learning of sensory patterns can lead to predictive neural processes enhancing stimulus perception and enabling fast deviancy detection. Predictive processes have been extensively demonstrated when environmental statistical regularities are relevant to task execution. Preliminary evidence indicates that statistical learning can even occur independently of task relevance and top-down attention, although the temporal profile and neural mechanisms underlying sensory predictions and error signals induced by statistical learning of incidental sensory regularities remain unclear. In our study, we adopted an implicit sensory conditioning paradigm that elicited the generation of specific perceptual priors in relation to task-irrelevant audio-visual associations, while recording Electroencephalography (EEG). Our results showed that learning of non-relevant but statistically interrelated neutral audio-visual stimuli resulted in early neural responses to predictive auditory stimuli conveying anticipatory signals of expected visual stimulus presence or absence, and in specific modulation of cortical responses to probabilistic visual stimulus presentation or omission. Pattern similarity analysis indicated that predictive auditory stimuli tended to resemble the response to expected visual stimulus presence or absence. Remarkably, Hierarchical Gaussian filter modeling estimating dynamic changes of prediction error signals in relation to differential probabilistic occurrences of audio-visual stimuli further demonstrated instantiation of predictive neural signals by showing distinct neural processing of prediction error in relation to violation of expected visual stimulus presence or absence. Overall, our findings indicated that statistical learning of non-salient and task-irrelevant perceptual regularities can induce the generation of neural priors at the time of predictive stimulus presentation, possibly conveying sensory-specific information of the predicted consecutive stimulus.

neuroscience↗

bioRxiv2021

Simulated visual hallucinations in virtual reality enhance cognitive flexibility

Historically, psychedelic drugs are known to modulate cognitive flexibility, a central aspect of cognition permitting adaptation to changing environmental demands. Despite proof suggesting phenomenological similarities between artificially-induced and actual psychedelic altered perception, experimental evidence is still lacking about whether the former is also able to modulate cognitive flexibility. To address this, we measure participants cognitive flexibility through behavioral tasks after the exposure to virtual reality panoramic videos and their hallucinatory-like counterparts generated by the DeepDream algorithm. Results show that the estimated semantic network has a flexible structure when preceded by altered videos. Crucially, following the simulated psychedelic exposure, individuals also show an attenuated contribution of the automatic process and chaotic dynamics underlying the decision process. This suggests that simulated altered perceptual phenomenology enhances cognitive flexibility, presumably due to a reorganization in the cognitive dynamics that facilitates the exploration of uncommon decision strategies and inhibits automated choices.

animal behavior and cognition↗