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Based on the Social Simulation Theory of dreaming (SST), we studied the effects of voluntary social seclusion on dream content and sleep structure. Specifically, we studied the CompensationHypothesis, which predicts social dream contents to increase during social seclusion, the SocialityBias – a ratio between dream and wake interactions – and the StrengtheningHypothesis, which predicts an increase in familiar dream characters during seclusion. Additionally, we assessed changes in the proportion of REM sleep. Sleep data and dream reports from 18 participants were collected preceding (n = 94), during (n = 90) and after (n = 119) a seclusion retreat. Data were analysed using linear mixed‐effects models. We failed to support the Compensation Hypothesis, with dreams evidencing fewer social interactions during seclusion. The Strengthening Hypothesis was supported, with more familiar characters present in seclusion dreams. Dream social interactions maintained the Sociality Bias even under seclusion. Additionally, REM sleep increased during seclusion, coinciding with previous literature and tentatively supporting the proposed attachment function for social REM sleep. [ABSTRACT FROM AUTHOR]

The human frontal cortex is asymmetrically involved in motivational and affective processing. Several studies have shown that the left‐frontal hemisphere is related to positive and approach‐related affect, whereas the right‐frontal hemisphere is related to negative and withdrawal‐related affect. The present study aimed to investigate whether evolutionarily threatening stimuli modulate asymmetrical frontal activity. We examined hemispheric differences in frontal late positive potentials (f‐LPP asymmetry) and frontal alpha power activation (frontal alpha asymmetry, FAA) in response to images depicting snakes, spiders, butterflies, and birds. Results showed that the late component of f‐LPP asymmetry, but not FAA, was modulated by the category of stimuli. Specifically, threatening stimuli (snakes and spiders) evoked a relatively large late f‐LPP over the right‐frontal hemisphere than non‐threatening stimuli (birds and butterflies). Moreover, this relatively great right‐frontal activity was positively associated with the subjective ratings of fear. Importantly, the subjective ratings of fear were not associated with early brain activity over the occipital or centro‐parietal cortices. These results suggest that late f‐LPP asymmetry may reflect higher order affective processes, specifically the subjective appraisal of threatening stimuli and the subjective experience of fear, that are independent of the fast and automatic processing of evolutionarily significant and affectively arousing stimuli. Findings regarding stimulus‐evoked hemispheric asymmetry over the frontal cortex are inconsistent. One reason for these inconsistencies may be the low salience of the stimuli often used in the experiments. Here, we show that highly salient threatening stimuli (snakes and spiders) modulate frontal asymmetry, and this is associated with how frightening these stimuli are perceived to be. Our results suggest that frontal asymmetry may reflect the subjective evaluation and experience of fear. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to compare the emotional content of dream reports collected at home upon morning awakenings with those collected in the laboratory upon early and late rapid eye movement (REM) sleep awakenings. Eighteen adults (11 women, seven men; mean age = 25.89 ± 4.85) wrote down their home dreams every morning immediately upon awakening during a 7‐day period. Participants also spent two non‐consecutive nights in the sleep laboratory where they were awoken 5 min into each continuous REM sleep stage, upon which they gave a verbal dream report. The content of a total of 151 home and 120 laboratory dream reports was analysed by two blind judges using the modified Differential Emotions Scale. It was found that: (1) home dream reports were more emotional than laboratory early REM dream reports, but not more emotional than laboratory late REM dream reports; (2) home dream reports contained a higher density of emotions than laboratory (early or late REM) dream reports; and (3) home dream reports were more negative than laboratory dream reports, but differences between home and early REM reports were larger than those between home and late REM reports. The results suggest that differences between home and laboratory dream reports in overall emotionality may be due to the time of night effect. Whether differences in the density of emotions and negative emotionality are due to sleep environment or due to different reporting procedures and time spent in a sleep stage, respectively, remains to be determined in future studies. [ABSTRACT FROM AUTHOR]

Studies on the neural basis of visual awareness, the subjective experience of seeing, have found several potential neural correlates of visual awareness. Some of them may not directly correlate with awareness but with post-perceptual processes, such as reporting one's awareness of the stimulus. We dissociated potential electrophysiological correlates of visual awareness from those occurring during response selection and thus co-occurring with post-perceptual processing. The participants performed two GO- NOGO conditions. In the aware- GO condition they responded with a key press when they were aware of the stimulus and withheld responding when they were unaware of it. In the unaware- GO condition they withheld responding when they were aware and responded when they were not aware of the stimulus. Thus, event-related potentials could be measured to aware and unaware trials when responding was required and when not required. The results revealed that the N200 amplitude (180-280 ms) over the occipital and posterior temporal cortex was enhanced in aware trials as compared with trials without awareness. This effect (visual awareness negativity, VAN) did not depend on responding. The amplitude of P3 (350-450 ms) also was enhanced in aware trials as compared with unaware trials. In addition, the amplitudes in the P3 time window depended on responding: they were greater when awareness was mapped to GO-response than when not, suggesting that P3 reflects post-perceptual processing, that is, it occurs after awareness has emerged. These findings support theories of visual awareness that assume a relatively early onset of visual awareness before P3. [ABSTRACT FROM AUTHOR]

During prolonged viewing of ambiguous stimuli, such as Necker cubes, sudden perceptual reversals occur from one perceptual interpretation to another. The role of attention in such reversals is not clear. We tested whether perceptual reversals depend on attentional resources by manipulating perceptual load and recording event-related potentials ( ERPs) during intermittent presentation of Necker stimuli. The results did not reveal any influence for perceptual load on the frequency of reversals. The ERPs showed that perceptual load influenced electrophysiological activity over parieto-central areas in the P1 time window (110-140 ms), but load did not modify the early enhancements of positivity (30-140 ms), which correlated with perceptual reversals at occipito-temporal sites. We conclude that disambiguation of ambiguous figures is based on early mechanisms that can work efficiently with only a minimal amount of attentional resources. [ABSTRACT FROM AUTHOR]

The primary visual cortex (V1) has been the target of stimulation in a number of transcranial magnetic stimulation (TMS) studies. In this study, we estimated the actual sites of stimulation by modeling the cortical location of the TMS-induced electric field when participants reported visual phosphenes or scotomas. First, individual retinotopic areas were identified by multifocal functional magnetic resonance imaging (mffMRI). Second, during the TMS stimulation, the cortical stimulation sites were derived from electric field modeling. When an external anatomical landmark for V1 was used (2 cm above inion), the cortical stimulation landed in various functional areas in different individuals, the dorsal V2 being the most affected area at the group level. When V1 was specifically targeted based on the individual mffMRI data, V1 could be selectively stimulated in half of the participants. In the rest, the selective stimulation of V1 was obstructed by the intermediate position of the dorsal V2. We conclude that the selective stimulation of V1 is possible only if V1 happens to be favorably located in the individual anatomy. Selective and successful targeting of TMS pulses to V1 requires MRI-navigated stimulation, selection of participants and coil positions based on detailed retinotopic maps of individual functional anatomy, and computational modeling of the TMS-induced electric field distribution in the visual cortex. It remains to be resolved whether even more selective stimulation of V1 could be achieved by adjusting the coil orientation according to sulcal orientation of the target site. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

It has been suggested that unconscious visual processing of some stimulus features might occur without the contribution of early visual cortex (V1/V2). In the present study, the causal role of V1/V2 in unconscious processing of simple shapes in intact human brain was studied by applying transcranial magnetic stimulation (TMS) on early visual cortex or lateral occipital cortex (LO) while observers performed a metacontrast-masked response priming task with arrow figures as visual stimuli. Magnetic stimulation of V1/V2 impaired masked priming 30-90 ms after the onset of the prime. Stimulation of LO reduced the magnitude of masked priming at 90-120 ms, but this effect occurred only in the early parts of the priming experiment. A control task measuring the visibility of masked primes indicated that the orientation of masked primes could not be consciously discriminated and that TMS did not influence the conscious visibility of the primes indirectly by reducing the effectiveness of the mask in the critical time windows. We conclude that feedforward sweep of processing from V1/V2 (30-90 ms) to LO (90 ms and above) is necessary for unconscious priming of shape, whereas conscious perception requires also the contribution of recurrent (feedback) processing. [ABSTRACT FROM AUTHOR]

Summary Motor activity in rapid eye movement (REM) sleep behaviour disorder (RBD) has been linked to dream content. Systematic and controlled sleep laboratory studies directly assessing the relation between RBD behaviours and experienced dream content are, however, largely lacking. We aimed to investigate whether a link can be established between RBD behaviours and dream content when both are systematically sampled in a controlled setting. We investigated six patients with Parkinson syndrome and RBD who underwent 2-3 nights of video-polysomnographic recording during which they were awakened from REM sleep (10 min after the onset of the second and successive REM periods). Spontaneous free-worded dream reports and a structured dream questionnaire were obtained. Video recordings of motor manifestations were each combined with four dream reports, and seven judges had to match the video clip with the correctly reported dream content from a choice of four possibilities. Of the 35 REM sleep awakenings performed, a total of 17 (48.6%) motor-behavioural episodes with recalled dream content were obtained. The mean of correctly identified video-dream pairs was 39.5% (range 0-100%). Our data showed that reported dream content can be linked to motor behaviours above chance level. Matching accuracy was affected mainly by the clarity of dream reports and the specific nature of movements manifest in video recordings. [ABSTRACT FROM AUTHOR]

Despite the complexity and methodological difficulties in defining the concept of consciousness, it is a central concept in epileptology, and should thus be tractable for scientific analysis. In the present article, a two-dimensional model consisting of concepts related to the level and the contents of consciousness will be presented. This model has been found to be well suited for the description of seizure-induced alterations of consciousness, and is supported both by findings from neuroimaging and electrophysiological studies as well as from phenomenological studies. Further, we will review both traditional introspective methods as well as methods that have recently been developed or utilized in epilepsy research, summarize the main findings concerning first person experiences during epileptic seizures acquired with some of these methods, and discuss their strengths and weaknesses. [ABSTRACT FROM AUTHOR]

The earliest reliably occurring event-related brain potential (ERP) correlate of visual awareness (visual awareness negativity, VAN) emerges after 100 ms and peaks between 200 and 300 ms from stimulus onset. In a study using low-contrast stimuli, VAN was significantly delayed, peaking at 460 ms ( V. Ojanen, A. Revonsuo, & M. Sams, 2003 ). In that study physical differences between the conscious and nonconscious stimuli may have confounded the results. Here we explored whether VAN is similarly delayed for physically identical stimuli. We presented low-contrast stimuli near an individually determined subjective contrast threshold. A delayed VAN peaked at 400 ms at occipito-temporal sites to subjectively perceived stimuli. Our results support the interpretation that VAN is the earliest ERP correlate of phenomenal visual awareness. The electrophysiological processes eliciting VAN may become delayed as a function of the difficulty of the early perceptual discrimination. [ABSTRACT FROM AUTHOR]

The concept of ‘hidden observer’ is one of the most controversial issues in hypnosis research. Green, Page, Handley and Rasekhy (this issue) approach it by using an ideomotor task which has not previously been used in association with the hidden observer. We regard their experiment as interesting; however, there are conceptual and methodological problems that hamper the impact of their study. In our commentary, we take the opportunity to point out some problems in their paper as well as to stress the importance to integrate concepts used in hypnosis research to mainstream cognitive neuroscience and consciousness research. [ABSTRACT FROM AUTHOR]

The main point of our article 'Hypnotic phenomena and altered states of consciousness: A multilevel framework of description and explanation' was to clarify, explicate and reveal the differences between current theoretical viewpoints in explaining hypnosis. Furthermore, we wanted to present a research programme and propose some experiments that if carried out, might lend decisive support to either the Nonstate View (NSV) or the State View (SV) approaches to hypnosis. The commentaries revealed that the concept of altered state of consciousness (ASC) still lacks a commonly accepted definition and is in need of further clarification. The controversy between NSV and SV of hypnosis seems to boil down to the question concerning the explanatory power of the neural level and especially to what the results at this level tell us. In this reply we further clarify the multi- level framework of explanation, the problems associated with the concept of ASC, and we explain the rationale for our proposal of using virtuosos as a model system in hypnosis research. [ABSTRACT FROM AUTHOR]

There is currently agreement that, in addition to the changes in external behaviour, suggestions presented in a hypnotic context may give rise to changes in subjective experience. Yet, there is no general agreement about the theoretical framework within which these changes in experience should be explained. Though different theories about hypnosis overlap in many respects, there is still disagreement on whether reference to a specific internal state of the individual is necessary in order to explain these changes. We place the explanatory task in the context of a multilevel framework of explanation, which reveals that the disagreement between the 'state' and 'nonstate'view is about the level of description at which the phenomenon 'hypnosis' should be conceptualized. We propose a novel approach using the multilevel explanation which helps to formulate empirically testable hypotheses about the nature of hypnosis. We will outline the basic elements of such an approach and hope that our proposition will help hypnosis research to integrate with the multidisciplinary research on other phenomena of consciousness. [ABSTRACT FROM AUTHOR]

Abstract Electrophysiological correlates of change detection and change blindness were studied in 12 observers. The ERP difference between detected changes and undetected changes was considered an electrophysiological correlate of visual awareness. Two distinct electrophysiological responses correlated with the awareness of change. First, awareness was associated with a negative amplitude shift at posterior sites around 200 ms after the change in the stimulus. The latency of the negative shift varied as a function of the task difficulty and the speed of becoming aware of the change. Second, ERPs to detected changes became more positive as compared with undetected changes around 400 ms after the change in the stimulus, peaking at parietal sites. We suggest that the earlier negativity is associated with a change in the content of visual awareness, whereas the later positivity may reflect more global processes needed in decision making and action planning. [ABSTRACT FROM AUTHOR]

Visual awareness was studied in 11 subjects by using coherent and scrambled objects as stimuli. The stimuli were presented near the subjective perceptual threshold. Explicitly recognized stimuli elicited a specific negative ERP deflection peaking at 460 ms. Our reaction time experiment suggests that this visual awareness negativity (VAN) is similar to that found previously at a shorter latency. We propose that VAN might reflect the exact moment of becoming aware of the task-relevant stimulus properties and provide an online marker of the temporal dynamics of visual awareness. [ABSTRACT FROM AUTHOR]

The study evaluated the off-line relationship of attention, memory and other cognitive performances with the auditory event-related potentials P3 (P300) and N2. The sample comprised 200 middle-aged construction workers. Verbal, visuomotor and memory tests were administered. Attentional domains were examined using CogniSpeed software. Slowed reaction times in the test of sustained attention (vigilance) were associated with delayed P3 latency ( p < 0.001) and decreased P3 amplitude ( p = 0.005), as well as with delayed N2 latency ( p < 0.001). Visuomotor slowing in Digit Symbol was also related to delayed P3 latency ( p = 0.030) and decreased P3 amplitude ( p = 0.014). In contrast, mild cognitive impairment, short- and long-term memory, and concentrating or sharing attention with high working memory demands were not related to P3. The results suggest that P3 is linked to attentional performance with low working memory demands rather than to effortful working memory updating, retrieval from memory stores, or mild cognitive impairment. [ABSTRACT FROM AUTHOR]

Cognitive functions associated with the frontal lobes of the brain may be specifically involved in hypnosis. Thus, the frontal area of the brain has recently been of great interest when searching for neural changes associated with hypnosis. We tested the hypothesis that EEG during pure hypnosis would differ from the normal non-hypnotic EEG especially above the frontal area of the brain. The composition of brain oscillations was examined in a broad frequency band (1–30 Hz) in the electroencephalogram (EEG) of a single virtuoso subject. Data was collected in two independent data collection periods separated by one year. The ‘hypnotic’ and ‘non-hypnotic’ conditions were repeated multiple times during each data acquisition session. We found that pure hypnosis induced reorganization in the composition of brain oscillations especially in prefrontal and right occipital EEG channels. Additionally, hypnosis was characterized by consistent right-side-dominance asymmetry. In the prefrontal EEG channels the composition of brain oscillations included spectral patterns during hypnosis that were completely different from those observed during non-hypnosis. Furthermore, the EEG spectral patterns observed overall during the hypnotic condition did not return to the pre-hypnotic baseline EEG immediately when hypnosis was terminated. This suggests that for the brain, the return to a normal neurophysiological baseline condition after hypnosis is a time-consuming process. The present results suggest that pure hypnosis is characterized by an increase in alertness and heightened attention, reflected as cognitive and neuronal activation. Taken together, the present data provide support for the hypothesis that in a very highly hypnotizable person (a hypnotic virtuoso) hypnosis as such may be accompanied by a changed pattern of neural activity in the brain. Copyright © 2007 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]