Spatial Perception: Time Tells Where a Smell Comes From

SummaryA new study has found that when a shark turns towards an odor, its directional decision is based on inter-nostril differences in odorant time of arrival, rather than on inter-nostril differences in odorant concentration

Consciousness is more than meets the eye: a call for a multisensory study of subjective experience

N.F. was an EPFL fellow co-funded by Marie Skłodowska-Curie. C.L. was funded by the project ECSPLAIN (European Research Council under the Seventh Framework Programme, FPT/2007-2013, grant agreement no. 338866). A.A. was a Blavatnik fellow and a Royal society Kohn international fellow. We thank the Association for the Scientific Study of Consciousness for travel funding, and we are grateful to Liad Mudrik, Lavi Secundo, Andrés Canales-Johnson, and Ophelia Deroy for valuable discussions and helpful comments on the article.International audienceOver the last 30 years, our understanding of the neurocognitive bases of consciousness has improved, mostly through studies employing vision. While studying consciousness in the visual modality presents clear advantages, we believe that a comprehensive scientific account of subjective experience must not neglect other exteroceptive and interoceptive signals as well as the role of multisensory interactions for perceptual and self-consciousness. Here, we briefly review four distinct lines of work which converge in documenting how multisensory signals are processed across several levels and contents of consciousness. Namely, how multisensory interactions occur when consciousness is prevented because of perceptual manipulations (i.e. subliminal stimuli) or because of low vigilance states (i.e. sleep, anesthesia), how interactions between exteroceptive and interoceptive signals give rise to bodily self-consciousness, and how multisensory signals are combined to form metacognitive judgments. By describing the interactions between multisensory signals at the perceptual, cognitive, and metacognitive levels, we illustrate how stepping out the visual comfort zone may help in deriving refined accounts of consciousness, and may allow cancelling out idiosyncrasies of each sense to delineate supramodal mechanisms involved during consciousness

Neural dynamics of associative learning during human sleep

Recent evidence indicate that humans can learn entirely new information during 3 sleep. To elucidate the neural dynamics underlying sleep-learning we investigated 4 brain activity during auditory-olfactory discriminatory associative learning in human 5 sleep. We found that learning-related delta and sigma neural changes are involved in 6 early acquisition stages, when new associations are being formed. In contrast, 7 learning-related theta activity emerged in later stages of the learning process, after 8 tone-odour associations were already established. These findings suggest that 9 learning new associations during sleep is signalled by a dynamic interplay between 10 slow-waves, sigma and theta activityThis work was supported by the Blavatnik family Foundation (to A.A.), Royal Society—Kohn International fellowship (NF150851 to A.A.), European Molecular Biology Organization (EMBO) fellowship (ALTF 33-2016 to A.A.), Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT N 1171200 to A.C.J.), and The Wellcome Trust (WT093811MA to T.A.B.). Collection of the data at the Weizmann Institute of Science in Israel was supported by the Rob and Cheryl McEwen Fund for Brain Research

Neural Dynamics of Associative Learning during Human Sleep

Abstract Recent evidence indicates that humans can learn entirely new information during sleep. To elucidate the neural dynamics underlying sleep-learning, we investigated brain activity during auditory–olfactory discriminatory associative learning in human sleep. We found that learning-related delta and sigma neural changes are involved in early acquisition stages, when new associations are being formed. In contrast, learning-related theta activity emerged in later stages of the learning process, after tone–odor associations were already established. These findings suggest that learning new associations during sleep is signaled by a dynamic interplay between slow-waves, sigma, and theta activity.</jats:p

Sniffing patterns uncover implicit memory for undetected odors

SummaryConsciously undetected events are represented at the sensory-motor level and in the neurons of sensory-motor control, for example, consciously undetected visual targets drive eye movements [1] and neural activity [2]. Olfaction offers an opportunity to investigate processing of undetected stimuli through measurements of the sniff-response: odorant-specific modulations of nasal airflow [3–6]. Here, we report evidence that consciously undetected odorants modulate sniffing in a predicted manner. Moreover, in our study we observed that sniff-modulations recurred at least 10 seconds after the onset of an undetected odor, implying that information which was not consciously perceived was nevertheless maintained in memory, available for future decision making

Minecraft and Paired Sounds and Smells (MAPS)

The overarching goal of this study is to elucidate the role sleep plays in consolidating interconnected, contextually rich memories in naturalistic settings using a well-powered experimental design. In this study, we will use multimodal cueing to selectively reactivate previously learned information during sleep. Previous studies have shown the effectiveness of using sounds or odors to reactivate and strengthen recently encoded information. Here, we propose using both types of sensory cues: one type (odor) associated with the context in which the information is learned and the other type (sound) associated with specific object-location associations. To test cognition in a more ecologically valid setting, we will use the Minecraft Memory and Navigation Task (MMN; Simon et al., 2022) . Participants will learn the locations of 12 items in a virtual environment while being exposed to item-associated sounds and an environmental-specific smell. Participants will be randomly assigned to a targeted cueing condition, either multimodal cues, unimodal cues or neither, conducted during a 90-minute nap directly after learning. We will compare spatial memory and navigation performance across groups to determine the role of multimodal sensory cues in sleep-dependent memory formation. We will explore how consolidation during sleep overcomes a major challenge posed by real-life circumstances – remembering multiple interacting memories encoded within the same context. This will be a multi-site collaborative study, conducted at University of California, Irvine (UCI) and at the Hebrew University of Jerusalem (HUJI). Study design and protocol will be identical across both sites

Neural dynamics of associative learning during human sleep

Recent evidence indicates that humans can learn entirely new information during sleep. To elucidate the neural dynamics underlying sleep-learning, we investigated brain activity during auditory–olfactory discriminatory associative learning in human sleep. We found that learning-related delta and sigma neural changes are involved in early acquisition stages, when new associations are being formed. In contrast, learning-related theta activity emerged in later stages of the learning process, after tone–odor associations were already established. These findings suggest that learning new associations during sleep is signaled by a dynamic interplay between slow-waves, sigma, and theta activity

Dynamic Auditory Remapping Across the Sleep-Wake Cycle

AbstractIn a single day we transition from vigilant wakefulness to unconscious sleep and dreaming, undergoing diverse behavioural, physiological and neural changes. While during the awake state, exogenous stimuli and endogenous changes lead to sensory reorganisation, this remapping has not been charted throughout the sleep-wake cycle. We recorded neural activity in response to a range of tones using electroencephalography during a full night’s sleep, and examined whether auditory responses become more similar, dissimilar or remain unchanged between wakefulness, non-rapid (NREM) and rapid eye movement (REM) sleep. We found that neural similarities between pairs of auditory evoked potentials differed by conscious state in both early and late auditory processing stages. Furthermore, tone-pairs neural similarities were modulated by conscious state as a function of tone frequency, where some tone-pairs changed similarity between states and others continued unaffected. These findings demonstrate a state-, stimulus- and time-dependent functional reorganization of auditory processing across the sleep-wake cycle.</jats:p