Biology subjects

Perl, O.

Publications and source records attributed to Perl, O..

6 recordsLinked to original sources

bioRxiv2026

Single neurons in the human substantia nigra encode social learning signals

Humans are remarkable at adapting to changing norms, yet we know little about how the human brain encodes these social signals at the single neuron level. Here, we recorded the activity of single neurons in the substantia nigra and globus pallidus in neurosurgical participants as they played an iterative ultimatum game versus human and computer avatars. Using computational modeling of behavior, we found that putative dopaminergic units in the substantia nigra tracked the valence of norm prediction errors, with greater encoding during gameplay with human versus computer avatars. Analogous analyses in the globus pallidus, a nucleus adjacent to the substantia nigra, found no significant effect. Our results identify a novel role for the substantia nigra in encoding social learning signals.

neuroscience↗

bioRxiv2026

A cortical hierarchy of sensory representations from physical structure to idiosyncratic perception

Perception begins with the physical structure of the external world, yet each of us remaps that structure into an idiosyncratic ordering shaped by individual experience and makeup. To ask how these two orderings are reflected in the brain, we used fMRI in 47 participants to measure the representation of olfactory and visual stimuli chosen such that similarities among the odorants mirrored those among the images. Olfactory and visual cortices each reflected physical similarity more strongly than idiosyncratic perceptual similarity. By contrast, a whole-brain search for the alternative uncovered the left angular gyrus, which reflected idiosyncratic perceptual similarity in both olfaction and vision. Connectivity analysis depicted this region as a likely hub for such representation, and dynamic causal modeling supported this observation. These findings reveal a transition from stimulus-centered representations in modality-specific sensory cortex to a modality-general observer-centered representation in the angular gyrus, suggesting a potentially fundamental hierarchy in brain organization.

neuroscience↗

bioRxiv2023

Respiration-Triggered Olfactory Stimulation ReducesObstructive Sleep Apnea Symptoms Severity: A Prospective Pilot Study

Obstructive sleep apnea (OSA) is a prevalent sleep-disordered breathing condition characterized by repetitive reduction in breathing during sleep. Current care standard for OSA is continuous positive air pressure devices, often suffering from low tolerance due to limited adherence. Capitalizing on the unique neurocircuitry of olfactory perception and its retained function during sleep, we conducted a pilot study to test transient, respiration-based olfactory stimulation as a treatment for OSA markers. Thirty-two OSA patients (Apnea-Hypopnea Index (AHI)[≥]15 events/hour) underwent two polysomnography sessions, Odor and Control, in random order. In Odor nights, patients were presented with transient respiratory-based olfactory stimulation delivered via a computer-controlled commercial olfactometer (Scentific). The olfactometer, equipped with a wireless monitoring, analyzed respiratory patterns and presented odor upon detection of respiratory events. No odors were presented in Control nights. Following exclusions, 17 patients entered analysis (4 women, 47.4 (10.5) years, BMI: 33.8 (7.8)). We observed that olfactory stimulation during sleep reduced AHI ( Odor:17.2 (20.9), Control: 28.2 (18.6), z=- 3.337, p=0.000846, BF10=57.9), reflecting an average decrease of 31.3% in event number. Relatedly, stimulation reduced the oxygen desaturation index (ODI) by 26.9% ( Odor: 12.5 (15.8), Control: 25.7 (25.9), z=-3.337, p=0.000846, BF10=9.522. This effect was not linked to baseline OSA markers severity ({rho}=-0.042, p=0.87). Olfactory stimulation did not arouse from sleep or affect sleep structure, measured as time per sleep stage (F(1,16)=0.088, p=0.77). In conclusion, olfactory stimulation during sleep was effective in reducing OSA markers severity without inducing arousals and may provide a novel treatment for OSA, prompting continued research.

physiology↗

bioRxiv2022

Neural patterns differentiate traumatic from sad autobiographical memories in PTSD

For people with post-traumatic stress disorder (PTSD), recalling traumatic memories often displays as intrusions that differ profoundly from processing of regular negative memories. These mnemonic features fueled theories speculating a qualitative divergence in cognitive state linked with traumatic memories. Yet to date, little empirical evidence supports this view. Here, we examined neural activity of PTSD patients who were listening to narratives depicting their own memories. An inter-subject representational similarity analysis of cross-subject semantic content and neural patterns revealed a differentiation in hippocampal representation by narrative type: Semantically similar sad autobiographical memories elicited similar neural representations across participants. By contrast, within the same individuals, semantically thematically similar trauma memories were not represented similarly. Furthermore, we were able to decode memory type from hippocampal multivoxel patterns. Finally, individual symptom severity modulated semantic representation of the traumatic narratives in the posterior cingulate cortex. Taken together, these findings suggest that traumatic memories are a qualitatively divergent cognitive entity.

neuroscience↗

bioRxiv2022

Nicotine-Related Beliefs Induce Dose-Dependent Responses in the Human Brain

Could non-pharmacological constructs, such as beliefs, impact brain activities in a dose-dependent manner as drugs do? While beliefs shape many aspects of our behavior and wellbeing, the precise mapping between subjective beliefs and neural substrates remains elusive. Here, nicotine-addicted humans were instructed to think that an electronic cigarette (e-cigarette) contained either "low", "medium", or "high" levels of nicotine, while nicotine content was kept constant. After vaping the e-cigarette, participants performed a decision-making task known to engage neural circuits affected by nicotine while being scanned by fMRI. Activity in the thalamus, a key binding site for nicotine, increased parametrically according to belief dosage. Furthermore, the functional coupling between thalamus and ventromedial prefrontal cortex, a region implicated in value and state representations, also scaled to belief dosage. These findings illustrate a dose-dependent relationship between a thalamic circuit and nicotine-related beliefs in humans, a mechanism previously known to only apply to pharmacological agents.

neuroscience↗

bioRxiv2019

Local Targeted Memory Reactivation in Human Sleep

Memory consolidation can be promoted via Targeted Memory Reactivation (TMR) that re-presents training cues or context during sleep. Whether TMR acts locally or globally on cortical sleep oscillations remains unknown. Here we exploit the unique functional neuroanatomy of olfaction with its ipsilateral stimulus processing to perform local TMR in one brain hemisphere. Participants learned associations between words and locations in left or right visual fields with contextual odor throughout. During post-learning naps, odors were presented to one nostril throughout NREM sleep. We found improved memory for specific words processed in the cued hemisphere (ipsilateral to stimulated nostril). Unilateral odor cues locally modulated slow wave activity (SWA) such that regional SWA increase in the cued hemisphere negatively correlated with select memories for cued words. Moreover, local TMR improved slow wave-spindle coupling specifically in the cued hemisphere. Thus, TMR in human sleep transcends global action by selectively promoting specific memories associated with local sleep oscillations.

neuroscience↗