Gaze differences in processing pictures with emotional content

The International Affective Picture System (IAPS) is a set of standardized emotionally evocative color photographs developed by NIMH Center for Emotion and Attention at the University of Florida. It contains more than 900 emotional pictures indexed by emotional valence, arousal and dominance. However, when IAPS pictures were used in studying emotions with the event-related potentials, the results have shown a great deal of variation and inconsistency. In this research arousal and dominance of pictures were controlled while emotional valence was manipulated as 3 categories, pleasant, neutral and unpleasant pictures. Two experiments were conducted with an eye-tracker in order to determine to what the participants turn their gaze. Participants were 25 psychology students with normal vision. Every participant saw all pictures in color and same pictures in black/white version. This makes 200 analyzed units for color pictures and 200 for black and white pictures. Every picture was divided into figure and ground. Considering that perception can be influenced by color, edges, luminosity and contrast and since all those factors are collapsed on the pictures in IAPS, we compared color pictures with same black and white pictures. In first eye-tracking IAPS research we analyzed 12 emotional pictures and showed that participants have higher number of fixations for ground on neutral and unpleasant pictures and for figure on pleasant pictures. Second experiment was conducted with 4 sets of emotional complementary pictures (pleasant/unpleasant) which differ only on the content in the figure area and it was shown that participants were more focused on the figure area than on the ground area. Future ERP (event related potential) research with IAPS pictures should take into consideration these findings and to either choose pictures with blank ground or adjust pictures in the way that ground is blank. For the following experiments suggestion is to put emotional content in the figure area and to use different non complementary pictures to see if there is difference between different emotional categories.     

Ultradian rhythms in processing speed of laterally exposed words and pictures

The study was designed to find out the cerebral hemispheres oscillations in stimuli processing during the 24-hour period of wakefulness in isolated subjects remaining in a monotonous environment. Stimuli processing speed from the 24-hour constant routine periods (06.00-06.00 h) of a larger experiment were analysed for the purpose of this paper. Parallel sets of words and pictures were exposed laterally using a purpose-designed computer program. The subjects reacted to pictures or words by pressing appropriate buttons. The significant dominant ultradian rhythms (around 4 h) in the processing speed of words addressed to the right hemisphere were found and of pictures addressed to the left hemisphere. Longer significant dominant periodicities (around 12 h) appeared in the processing speed of words addressed to the left hemisphere and of pictures (around 8 h) addressed to the right hemisphere. Ultradian rhythmicity of the central nervous system functioning is suggested.     

Visual processing: parallel-er and parallel-er

The mammalian visual system processes many different aspects of the visual scene in separate, parallel channels. Recent experiments suggest that the visual cortex, like the retina, forms parallel circuits even at very fine spatial scales.     

Visual priming and perception of small pictures in a scene with multiscale objects

Biederman et al. [1, 2] have shown that the priming effect does not depend on the difference between the angular sizes of the test stimulus and the primer. However, these two and other similar studies investigated only a small range of the angular sizes of stimuli. Vakhrameeva et al. [3] have shown that there exist two perceptionally different size ranges: perception of the objects with an angular size varying between 1–1.5 and 50 degrees was found to be invariant, but for the objects whose angular size is less than 1–1.5 degrees, their perception is no longer invariant. In this study, the presence of the priming effect has been investigated in the match-to-sample task with such a difference in the angular sizes of the primer and test stimuli that the sizes of the primer (about 4 degrees) and the test stimulus (about 0.5 degrees) belonged to two different size ranges. The sample stimulus was presented with and without noise superposition. It has been shown that the priming effect is suppressed when the size difference between the primer and the test stimulus is large. A congruent primer can have a positive impact on the recognition of the test objects, but this occurs under the viewing conditions complicated by noise superposition.     

Affective pictures processing is reflected by an increased long-distance EEG connectivity

Analysis of affective picture processing by means of EEG has invaded the literature. The methodology of event-related EEG coherence is one of the essential methods used to analyze functional connectivity. The aims of the present study are to find out the long range EEG connectivity changes in perception of different affective pictures and analyze gender differences in these long range connected networks. EEGs of 28 healthy subjects (14 female) were recorded at 32 locations. The participants passively viewed emotional pictures (IAPS, unpleasant, pleasant, neutral). The long-distance intra-hemispheric event-related coherence was analyzed for delta (1–3.5 Hz), theta (4–7.5 Hz), and alpha (8–13 Hz) frequency ranges for F₃–T₇, F₄–T₈, F₃–TP₇, F₄–TP₈, F₃–P₃, F₄–P₄, F₃–O₁, F₄–O₂, C₃–O₁, C₄–O₂ electrode pairs. Unpleasant pictures elicited significantly higher delta coherence values than neutral pictures (p < 0.05), over fronto-parietal, fronto-occipital, and centro-occipital electrode pairs. Furthermore, unpleasant pictures elicited higher theta coherence values than pleasant (p < 0.05) and neutral pictures (p < 0.05). The present study showed that female subjects had higher delta (p < 0.05) and theta (p < 0.05) coherence values than male subjects. This difference was observed more for emotional pictures than for neutral pictures. This study showed that the brain connectivity was higher during emotional pictures than neutral pictures. Females had higher connectivity between different parts of the brain than males during emotional processes. According to these results, we may comment that increased valence and arousal caused increased brain activity. It seems that not just single sources but functional networks were also activated during perception of emotional pictures.     

Visual information processing in the fly's landing system

Summary When approaching a landing site flies (Musca domestica) extend their legs in order to prevent crash-landing. Pattern expansion in front of a tethered fly can mimic an approach towards a landing site. Under these conditions landing is a rather stereotyped motor pattern. Only the latency of the onset of the landing response varies with the stimulus strength. Quantitative studies of the stimulus-latency relationship led to the formulation of a simple model which describes the way movement information at the fly's retina is processed in order to trigger landing. We propose that the output of local directionally selective movement detectors are spatially pooled and subsequently integrated in time. Whenever the level of this integrated signal reaches a fixed threshold landing is released.     

Visual neuroscience: computational brain dynamics of face processing

A recent study of how the brain processes emotionally expressive faces has revealed how task-relevant information is first gathered from the region around the eyes and then integrated downwards until categorization is achieved.     

Visual processing: the devil is in the details

Ganglion cells convey information from the retina back to the brain. Recent experiments have examined how ganglion cell receptive fields are assembled from many incoming signals.     

The time course of the influence of valence and arousal on the implicit processing of affective pictures

In the current study, we investigated the time course of the implicit processing of affective pictures with an orthogonal design of valence (negative vs. positive) by arousal (low vs. high). Previous studies with explicit tasks suggested that valence mainly modulates early event-related potential (ERP) components, whereas arousal mainly modulates late components. However, in this study with an implicit task, we observed significant interactions between valence and arousal at both early and late stages over both parietal and frontal sites, which were reflected by three different ERP components: P2a (100-200 ms), N2 (200-300 ms), and P3 (300-400 ms). Furthermore, there was also a significant main effect of arousal on P2b (200-300 ms) over parieto-occipital sites. Our results suggest that valence and arousal effects on implicit affective processing are more complicated than previous ERP studies with explicit tasks have revealed.     

Visual and socio-cognitive information processing in primate brain evolution.

Social group size has been shown to correlate with neocortex size in primates. Here we use comparative analyses to show that social group size is independently correlated with the size of non-V1 neocortical areas, but not with other more proximate components of the visual system or with brain systems associated with emotional cueing (e.g. the amygdala). We argue that visual brain components serve as a social information ''input device'' for socio-visual stimuli such as facial expressions, bodily gestures and visual status markers, while the non-visual neocortex serves as a ''processing device'' whereby these social cues are encoded, interpreted and associated with stored information. However, the second appears to have greater overall importance because the size of the V1 visual area appears to reach an asymptotic size beyond which visual acuity and pattern recognition may not improve significantly. This is especially true of the great ape clade (including humans), that is known to use more sophisticated social cognitive strategies.     

Visual cortex: cartography, connectivity, and concurrent processing.

The mammalian visual cortex contains a complex mosaic of areas that are richly connected with one another. Recent progress has advanced our understanding of both macroscopic and microscopic aspects of cortical organization, and of information flow within and between functionally specialized processing streams.     

Visual motion processing investigated using contrast agent-enhanced fMRI in awake behaving monkeys.

To reduce the information gap between human neuroimaging and macaque physiology and anatomy, we mapped fMRI signals produced by moving and stationary stimuli (random dots or lines) in fixating monkeys. Functional sensitivity was increased by a factor of approximately 5 relative to the BOLD technique by injecting a contrast agent (monocrystalline iron oxide nanoparticle [MION]). Areas identified as motion sensitive included V2, V3, MT/V5, vMST, FST, VIP, and FEF (with moving dots), as well as V4, TE, LIP, and PIP (with random lines). These regions sensitive for moving dots are largely in agreement with monkey single unit data and (except for V3A) with human fMRI results. Moving lines activate some regions that have not been previously implicated in motion processing. Overall, the results clarify the relationship between the motion pathway and the dorsal stream in primates.     

Moving pictures of the human microbiome

Background

Understanding the normal temporal variation in the human microbiome is critical to developing treatments for putative microbiome-related afflictions such as obesity, Crohn's disease, inflammatory bowel disease and malnutrition. Sequencing and computational technologies, however, have been a limiting factor in performing dense time series analysis of the human microbiome. Here, we present the largest human microbiota time series analysis to date, covering two individuals at four body sites over 396 timepoints.

Results

We find that despite stable differences between body sites and individuals, there is pronounced variability in an individual's microbiota across months, weeks and even days. Additionally, only a small fraction of the total taxa found within a single body site appear to be present across all time points, suggesting that no core temporal microbiome exists at high abundance (although some microbes may be present but drop below the detection threshold). Many more taxa appear to be persistent but non-permanent community members.

Conclusions

DNA sequencing and computational advances described here provide the ability to go beyond infrequent snapshots of our human-associated microbial ecology to high-resolution assessments of temporal variations over protracted periods, within and between body habitats and individuals. This capacity will allow us to define normal variation and pathologic states, and assess responses to therapeutic interventions.