| 1. |
- Arshamian, Artin, et al.
(författare)
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A mammalian blood odor component serves as an approach-avoidance cue across phylum border - from flies to humans
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Chemosignals are used by predators to localize prey and by prey to avoid predators. These cues vary between species, but the odor of blood seems to be an exception and suggests the presence of an evolutionarily conserved chemosensory cue within the blood odor mixture. A blood odor component, E2D, has been shown to trigger approach responses identical to those triggered by the full blood odor in mammalian carnivores and as such, is a key candidate as a food/alarm cue in blood. Using a multidisciplinary approach, we demonstrate that E2D holds the dual function of affecting both approach and avoidance behavior in a predator-prey predicted manner. E2D evokes approach responses in two taxonomically distant blood-seeking predators, Stable fly and Wolf, while evoking avoidance responses in the prey species Mouse. We extend this by demonstrating that this chemical cue is preserved in humans as well; E2D induces postural avoidance, increases physiological arousal, and enhances visual perception of affective stimuli. This is the first demonstration of a single chemical cue with the dual function of guiding both approach and avoidance in a predator-prey predicted manner across taxonomically distant species, as well as the first known chemosignal that affects both human and non-human animals alike.
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| 2. |
- Gerhardsson, Andreas, et al.
(författare)
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Does insufficient sleep affect how you learn from reward or punishment? Reinforcement learning after 2 nights of sleep restriction
- 2021
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 30:4
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Tidskriftsartikel (refereegranskat)abstract
- To learn from feedback (trial and error) is essential for all species. Insufficient sleep has been found to reduce the sensitivity to feedback as well as increase reward sensitivity. To determine whether insufficient sleep alters learning from positive and negative feedback, healthy participants (n = 32, mean age 29.0 years, 18 women) were tested once after normal sleep (8 hr time in bed for 2 nights) and once after 2 nights of sleep restriction (4 hr/night) on a probabilistic selection task where learning behaviour was evaluated in three ways: as generalised learning, short-term win-stay/lose-shift learning strategies, and trial-by-trial learning rate. Sleep restriction did not alter the sensitivity to either positive or negative feedback on generalised learning. Also, short-term win-stay/lose-shift strategies were not affected by sleep restriction. Similarly, results from computational models that assess the trial-by-trial update of stimuli value demonstrated no difference between sleep conditions after the first block. However, a slower learning rate from negative feedback when evaluating all learning blocks was found after sleep restriction. Despite a marked increase in sleepiness and slowed learning rate for negative feedback, sleep restriction did not appear to alter strategies and generalisation of learning from positive or negative feedback.
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| 3. |
- Peter, Moa G., et al.
(författare)
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Sensory loss enhances multisensory integration performance
- 2019
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Ingår i: Cortex. - : Elsevier BV. - 0010-9452 .- 1973-8102. ; 120, s. 116-130
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Tidskriftsartikel (refereegranskat)abstract
- Auditory and visual sensory loss has repeatedly been shown to alter abilities in remaining sensory modalities. It is, however, unclear whether sensory loss also impacts multisensory integration; an ability that is fundamental for the perception of the world around us. We determined effects of olfactory sensory deprivation on multisensory perception by assessing temporal as well as semantic aspects of audio-visual integration in 37 individuals with anosmia (complete olfactory sensory loss) and 37 healthy, matched controls. Participants performed a simultaneity judgement task to determine the temporal binding window, and a multisensory object identification task with individually degraded, dynamic visual, auditory, and audio-visual stimuli. Individuals with anosmia demonstrated an increased ability to detect multisensory temporal asynchronies, represented by a narrowing of the audio-visual temporal binding window. Furthermore, individuals with congenital, but not acquired, anosmia demonstrated indications of greater benefits from bimodal, as compared to unimodal, stimulus presentation when faced with degraded, semantic information. This suggests that the absence of the olfactory sense alters multisensory integration of remaining senses by sharpening the perception of cross-modal temporal violations, independent of sensory loss etiology. In addition, congenital sensory loss may further lead to increased gain from multisensory, compared to unisensory, information. Taken together, multisensory compensatory mechanisms at different levels of perceptual complexity are present in individuals with anosmia.
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| 4. |
- Porada, Danja K
(författare)
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An object's smell in the multisensory brain : how our senses interact during olfactory object processing
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Object perception is a remarkable and fundamental cognitive ability that allows us to interpret and interact with the world we are living in. In our everyday life, we constantly perceive objects–mostly without being aware of it and through several senses at the same time. Although it might seem that object perception is accomplished without any effort, the underlying neural mechanisms are anything but simple. How we perceive objects in the world surrounding us is the result of a complex interplay of our senses. The aim of the present thesis was to explore, by means of functional magnetic resonance imaging, how our senses interact when we perceive an object’s smell in a multisensory setting where the amount of sensory stimulation increases, as well as in a unisensory setting where we perceive an object’s smell in isolation. In Study I, we sought to determine whether and how multisensory object information influences the processing of olfactory object information in the posterior piriform cortex (PPC), a region linked to olfactory object encoding. In Study II, we then expanded our search for integration effects during multisensory object perception to the whole brain because previous research has demonstrated that multisensory integration is accomplished by a network of early sensory cortices and higher-order multisensory integration sites. We specifically aimed at determining whether there exist cortical regions that process multisensory object information independent of from which senses and from how many senses the information arises. In Study III, we then sought to unveil how our senses interact during olfactory object perception in a unisensory setting. Other previous studies have shown that even in such unisensory settings, olfactory object processing is not exclusively accomplished by regions within the olfactory system but instead engages a more widespread network of brain regions, such as regions belonging to the visual system. We aimed at determining what this visual engagement represents. That is, whether areas of the brain that are principally concerned with processing visual object information also hold neural representations of olfactory object information, and if so, whether these representations are similar for smells and pictures of the same objects. In Study I we demonstrated that assisting inputs from our senses of vision and hearing increase the processing of olfactory object information in the PPC, and that the more assisting input we receive the more the processing is enhanced. As this enhancement occurred only for matching inputs, it likely reflects integration of multisensory object information. Study II provided evidence for convergence of multisensory object information in form of a non-linear response enhancement in the inferior parietal cortex: activation increased for bimodal compared to unimodal stimulation, and increased even further for trimodal compared to bimodal stimulation. As this multisensory response enhancement occurred independent of the congruency of the incoming signals, it likely reflects a process of relating the incoming sensory information streams to each other. Finally, Study III revealed that regions of the ventral visual object stream are engaged in recognition of an object’s smell and represent olfactory object information in form of distinct neural activation patterns. While the visual system encodes information about both visual and olfactory objects, it appears to keep information from the two sensory modalities separate by representing smells and pictures of objects differently. Taken together, the studies included in this thesis reveal that olfactory object perception is a multisensory process that engages a widespread network of early sensory as well higher-order cortical regions, even if we do not encounter ourselves in a multisensory setting but exclusively perceive an object’s smell.
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| 5. |
- Porada, Danja K., et al.
(författare)
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Multisensory Enhancement of Odor Object Processing in Primary Olfactory Cortex
- 2019
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 418, s. 254-265
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Tidskriftsartikel (refereegranskat)abstract
- Identification of an object based on its odor alone is inherently difficult, but becomes easier when other senses provide supporting cues. This suggests that crossmodal sensory input facilitates neural processing of olfactory object information; however, direct evidence is still lacking. Here, we tested the effect of multisensory stimulation on information processing in the human posterior piriform cortex (PPC), a region linked to olfactory object encoding. Participants were exposed to familiar objects in the form of uni-, bi-, and trimodal combinations of odors, videos, and sounds. We hypothesized that the PPC would respond to non-olfactory object information, and that activity would increase linearly with the number of senses providing relevant object information. As predicted, visual object information activated the PPC and activity increased linearly with the number of relevant sensory channels. The crossmodal response pattern thus indicates that the PPC does not exclusively respond to olfactory information, but also to crossmodal object information important for olfactory processing. The continuous activity increase suggests that the PPC further acts as a multisensory binding site where pertinent input from multiple senses results in an increased neural response to the odor object. This potentially represents a neural mechanism for the well-known behavioral improvement present in odor object recognition during concurrent crossmodal sensory stimulation.
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| 6. |
- Porada, Danja K., et al.
(författare)
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Trimodal processing of complex stimuli in inferior parietal cortex is modality-independent
- 2021
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Ingår i: Cortex. - : Elsevier BV. - 0010-9452 .- 1973-8102. ; 139, s. 198-210
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Tidskriftsartikel (refereegranskat)abstract
- In humans, multisensory mechanisms facilitate object processing through integration of sensory signals that match in their temporal and spatial occurrence as well as their meaning. The generalizability of such integration processes across different sensory modalities is, however, to date not well understood. As such, it remains unknown whether there are cerebral areas that process object-related signals independently of the specific senses from which they arise, and whether these areas show different response profiles depending on the number of sensory channels that carry information.To address these questions, we presented participants with dynamic stimuli that simultaneously emitted object-related sensory information via one, two, or three channels (sight, sound, smell) in the MR scanner. By comparing neural activation patterns between various integration processes differing in type and number of stimulated senses, we showed that the left inferior frontal gyrus and areas within the left inferior parietal cortex were engaged independently of the number and type of sensory input streams. Activation in these areas was enhanced during bimodal stimulation, compared to the sum of unimodal activations, and increased even further during trimodal stimulation.Taken together, our findings demonstrate that activation of the inferior parietal cortex during processing and integration of meaningful multisensory stimuli is both modality-independent and modulated by the number of available sensory modalities. This suggests that the processing demand placed on the parietal cortex increases with the number of sensory input streams carrying meaningful information, likely due to the increasing complexity of such stimuli.
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| 7. |
- Regenbogen, Christina, et al.
(författare)
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Behavioral and neural correlates to multisensory detection of sick humans
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:24, s. 6400-6405
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Tidskriftsartikel (refereegranskat)abstract
- Throughout human evolution, infectious diseases have been a primary cause of death. Detection of subtle cues indicating sickness and avoidance of sick conspecifics would therefore be an adaptive way of coping with an environment fraught with pathogens. This study determines how humans perceive and integrate early cues of sickness in conspecifics sampled just hours after the induction of immune system activation, and the underlying neural mechanisms for this detection. In a double-blind placebo-controlled crossover design, the immune system in 22 sample donors was transiently activated with an endotoxin injection [lipopolysaccharide (LPS)]. Facial photographs and body odor samples were taken from the same donors when sick (LPS-injected) and when healthy (saline-injected) and subsequently were presented to a separate group of participants (n = 30) who rated their liking of the presented person during fMRI scanning. Faces were less socially desirable when sick, and sick body odors tended to lower liking of the faces. Sickness status presented by odor and facial photograph resulted in increased neural activation of odor-and faceperception networks, respectively. A superadditive effect of olfactory-visual integration of sickness cues was found in the intraparietal sulcus, which was functionally connected to core areas of multisensory integration in the superior temporal sulcus and orbitofrontal cortex. Taken together, the results outline a disease-avoidance model in which neural mechanisms involved in the detection of disease cues and multisensory integration are vital parts.
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