Introduction Altered subjective visual sensitivity manifests as feelings of discomfort or overload elicited by intense and irritative visual stimuli. This can result in a host of visual aberrations including visual distortions, elementary visual hallucinations and visceral responses like dizziness and nausea, collectively referred to as “pattern glare.” Current knowledge of the underlying neural mechanisms has focused on overall excitability of the visual cortex, but the individual contribution of excitatory and inhibitory systems has not yet been quantified. Methods In this study, we focus on the role of glutamate and γ-aminobutyric acid (GABA) as potential mediators of individual differences in subjective visual sensitivity, measured by a computerized Pattern Glare Test—a series of monochromatic square-wave gratings with three different spatial frequencies, while controlling for psychological variables related to sensory sensitivity with multiple questionnaires. Resting neurotransmitter concentrations in primary visual cortex (V1) and right anterior insula were studied in 160 healthy participants using magnetic resonance spectroscopy. Results Data showed significant differences in the perception of visual distortions (VD) and comfort scores between men and women, with women generally reporting more VD, and therefore the modulatory effect of sex was considered in a further examination. A general linear model analysis showed a negative effect of occipital glutamate on a number of reported visual distortions, but also a significant role of several background psychological traits. When assessing comfort scores in women, an important intervening variable was the menstrual cycle. Discussion Our findings do not support that baseline neurotransmitter levels have a significant role in overreactivity to aversive stimuli in neurotypical population. However, we demonstrated that biological sex can have a significant impact on subjective responses. Based on this additional finding, we suggest that future studies investigate aversive visual stimuli while examining the role of biological sex.
Abstract Social touch may modulate emotions, but the neurobehavioral correlates are poorly understood. Here, we investigated neural responses to a picture of a deceased close person and if neural activity and connectivity are modulated by social touch from one’s romantic partner. Using functional magnetic resonance imaging, we found altered reactivity in several brain areas including the anterior cingulate cortex (ACC) and the anterior insula in response to the personal picture compared to a picture of an unfamiliar person. Hand holding with the romantic partner, compared to being alone, reduced reactivity in the ACC and cerebellum and provided subjective comfort. To separate physical touch from the emotional effect of partner presence, we evaluated hand holding with the partner relative to a stranger and found reduced reactivity in the anterior insula. Connectivity between the anterior insula and the ACC was reduced during partner touch, and the connectivity strength was negatively related to attachment security, with higher reported partner security associated with weaker connectivity. Overall, holding hands with one’s partner attenuates reactivity in emotional brain areas and reduces between-region connectivity.
Summary Perceptual experience is a multi-faceted, dynamical process, tackled empirically through measures of stimulus detectability and confidence. To assess if stimulus detection and confidence can be explained by evidence accumulation, a form of sequential sampling of sensory evidence, we analyzed high-gamma activity from stereo-electroencephalographic data of 29 participants partaking in 3 pre-registered experiments. In an immediate-response experiment, individual channels and decoded multivariate latent variables in the visual, inferior frontal, and anterior insular cortices displayed functional markers of evidence accumulation. In two further experiments, this signal in the ventral visual cortex differentiated between (1) seen and unseen stimuli in delayed detection, (2) high and low intensity stimuli during passive viewing, and (3) levels of confidence when stimuli were seen. A computational model of leaky evidence accumulation successfully reproduced both behavioral and neural data. Overall, these results indicate that evidence accumulation explains key aspects of perceptual experience, encompassing both conscious access and monitoring.
The human mind, trying to perceive events coherently, creates the illusion of continuous time passage. Empirical evidence suggests distortions in subjectively perceived time flow associated with well-studied neural responses to sensory stimuli. This study aimed to investigate whether visually uncomfortable patterns, causing exceptionally strong brain activation, affect short time estimates and whether these estimates vary based on the overall reported sensory sensitivity and cortical excitability of individuals. Two experiments in virtual reality testing our assumptions at different levels of complexity of timed stimuli provided initial insight into the studied processes in highly controlled and realistic conditions. Data analysis results did not support our hypotheses, but showed that subjectively most visually uncomfortable simple patterns, i.e., achromatic gratings, cause more variable temporal judgments. Supposedly, this inaccuracy depends on the currently perceived visual comfort and thus the current visual system sensitivity, which cannot be satisfactorily derived from trait-based measures. The exploration of the effect of complex stimuli, i.e., virtual exteriors, suggested that their visual comfort does not affect time perception at all. Biological sex was an important variable across experiments, as males experienced temporal compression of stimuli compared to females. Neuroimaging research is needed for a deeper investigation of the origin of these results. Protocol registration: The Stage 1 manuscript associated with this Registered Report was in-principle accepted on 4 March 2024 prior to data collection for hypothesis testing. The accepted version of the manuscript can be found in the publicly available OSF repository at https://doi.org/ https://doi.org/10.17605/OSF.IO/K3YZE .
V doplnění kontextu informací o šibenici ze Slavkova byla provedena archeozoologická analýza, s cílem popsat výskyt živočichů na této lokalitě a rozšířit tak možnosti interpretace archeologické situace. Analyzovaný osteologický materiál byl na základě podrobného zhodnocení tafonomických projevů na kostech rozčleněn do dvou chronologických úseků – první náležející původnímu kontextu provozu šibenice, druhý spíše recentního charakteru. Z prvního období pochází šest druhů domácí i volně žijící fauny, v mladší části souboru bylo identifikováno několik druhů malých či drobných savců, a také pozůstatky ptactva. Lidské zásahy, které byly pozorovány na domestikované fauně ve starším období, svědčí o využití těchto zvířat v rámci potravní strategie lidí na popravišti; stopy natrávení žaludečními šťávami a charakteristické lomy na některých kostech volně žijící fauny v obou etapách odkazují na možné nahromadění vývržků dravým ptactvem.
Mental imagery related to the recent death of a loved one is associated with intense sadness and distress. Social relations, such as with one's significant other, can regulate negative emotions and provide comfort, but the neural correlates of social comfort are largely unknown. In this functional magnetic resonance imaging study, we examined brain responses to sad mental imagery and how these are modulated by holding hands with one's romantic partner. We found that mental imagery of a recently deceased loved one was associated with increased reactivity in the dorsal striatum, medial prefrontal cortex, anterior and posterior cingulate cortex, thalamus and cerebellum. Holding hands with one's partner as compared to being alone or holding hands with a stranger provided subjective comfort and reduced neural reactivity in the dorsal striatum without affecting the vividness of the imagery. Our findings indicate an important role for the dorsal striatum in sad mental imagery and social comfort and suggest that tactile social support by one's romantic partner regulates subjective distress through other processes than mere distraction from the mental imagery.
The article introduces an original VR-based experiment which explores context-dependent memory recall in humans. It specifically examines the recall of correct and falsely induced semantic memories. With the aid of VR head-mounted displays, 92 students of psychology were placed in a computer-generated indoor virtual environment and asked to memorize the presented lists of words. Afterwards, the participants were placed in the same indoor virtual environment or an alternative outdoor virtual environment and asked to recall the words. The number of correct and falsely induced words was then measured. On average, women recalled significantly more correct words from the list than men, regardless of the environmental context. Despite the assumptions, we did not observe a separate effect of exposure to different environments during learning and recall of material on memory performance. Likewise, we did not detect any effects of the learning context or biological sex in the case of the production of false memories. These results provide a novel insight into previous knowledge regarding the memory processes that occur in virtual environments. Although we failed to confirm the role of context in recalling learned material in general, we found a hint that this context might interact with specific memory processes of biological sexes. However, the design of this study only captured the effect of changing the environment during memory recall and did not address the role of specific context in remembering learning material. Further research is therefore needed to better investigate these phenomena and examine the role of biological sex in context-dependent memory processes.
Animals have an important role in human lives, either the species kept as human companions or the ones kept as a source of food and organic raw materials. This study is mainly about the second category, it research food strategies of the people of Unětice culture in settlement of Pasohlavky on the basis of archeozoological analysis of animal remains. Identified bones and fragments belonged both to domesticated and wild fauna, domesticated species were in notable majority. There have been observed signs of human activity on the remains, such as cut marks made in connection with preparation of animal bodies for feeding inhabitants, and different level of burning connected with the heat treatment of the meat. There were found two bone fragments modified into form of sharp tools. The obtained results are in accordance to the expected concept of handling with domestic fauna by people of the Unětice culture.
