Spatial Analysis of the Social World

Every time you inhale the savory aromas of a home-cooked meal or the pungent smell of strong perfume, different spatial patterns of activity are evoked in odor-processing regions of the brain. Moreover, different odors elicit patterns of activity that evolve in different ways over time. For example, the timing of neuronal activity in a brain region called the olfactory bulb, relative to when an animal sniffs, conveys important information about odors. Yet relatively little is known about the behavioral relevance of the timing information generated by patterns of activity in the olfactory bulb. In a study published this week in PLOS Biology, Justus V. Verhagen of the John B. Pierce Laboratory and his collaborators provide evidence that the mammalian olfactory system is capable of very high rates of transmission of transient information. Using an innovative optogenetics approach, they found that mice can precisely discriminate virtual odors associated with patterns of neuronal activity that differed by as little as 13 ms. According to the authors, the ability to rapidly and accurately recognize odors could provide a survival advantage, putting evolutionary pressure on the brain to maximize the use of odor information at the earliest stages of sensory processing. To precisely control the timing of neuronal activity produced by virtual odors, Verhagen and his team used genetically engineered mice that expressed channelrhodopsin 2 (a light-sensitive protein originally isolated from the alga Chlamydomonas reinhardtii that functions as an ion channel) in a subset of olfactory bulb neurons called mitral/tufted cells. Exposure to light opened channelrhodopsin 2, allowing ions to flow inside and excite these cells. Using a novel customdesigned light projector, the researchers projected high-resolution, sniff-triggered movies onto the olfactory bulb to activate the cells and thereby stimulate the perception of virtual odors. All of the movies consisted of the same spatial pattern of eight light spots. However, in static movies, all eight spots were projected simultaneously onto the olfactory bulb, whereas in dynamic movies, one set of four spots was presented before the second set of four spots. The mice were trained to discriminate between the virtual odors by licking a spout for a water reward in response to stimulation with dynamic movies but not in response to stimulation with static movies. The researchers set out to determine the threshold at which mice could accurately discriminate between the virtual odors based on neuronal activity in the olfactory bulb. To do so, they systematically decreased the delay between the two sets of four spots in the dynamic movie. When the two sets of spots were separated by 13 ms, the mice still achieved an accuracy of more than 75%. The findings highlight the impressive temporal precision of the olfactory system, which is comparable to the sense of touch and much higher than the sense of taste. To establish the biological relevance of this ability to detect timing differences, the researchers created movies based on recordings of neuronal activity in the olfactory bulb of a mouse exposed to a fruity odor. These virtual odor movies were then projected onto the olfactory bulb of the genetically engineered mice. The animals were able to distinguish between these dynamic movies and static virtual odor movies that produced the same spatial pattern of neuronal activity but contained no timing information. To assess whether this temporal precision depended on the timing of neuronal activation relative to sniffing, the researchers introduced a variable jitter, ranging from zero to 50 ms, after the mice sniffed and before the movie played. The performance of the mice was unaffected by the jitter, suggesting that the temporal pat-

Probabilistic atlases for face and biological motion perception: an analysis of their reliability and overlap.

Speech in everyday life is often masked by background noise, making comprehension effortful. Characterizing brain activity patterns when individuals listen to masked speech can help clarify the mechanisms underlying such effort. In the current study, we used functional magnetic resonance imaging (fMRI) in humans of either sex to investigate how neural signatures of story listening change in the presence of masking noise. We show that, as speech masking increases, spatial and temporal activation patterns in auditory regions become more idiosyncratic to each listener. In contrast, spatial activity patterns in brain networks linked to effort (e.g., cingulo-opercular network) are more similar across listeners when speech is highly masked and less intelligible, suggesting shared neural processes. Moreover, at times during stories when one meaningful event ended and another began, neural activation increased in frontal, parietal, and medial cortices. This event-boundary response appeared little affected by background noise, suggesting that listeners process meaningful units and, in turn, the gist of naturalistic, continuous speech even when it is masked somewhat by background noise. The current data may indicate that people stay engaged and cognitive processes associated with naturalistic speech processing remain intact under moderate levels of noise, whereas auditory processing becomes more idiosyncratic to each listener.

BackgroundNeighbourhood socioeconomic status (SES) has been shown to be related to health status and overweight independent of individual SES. However, results about the association between neighbourhood SES and physical activity among children are ambiguous. Particularly, it is unknown how socioeconomic factors influence the spatial context of children’s moderate-vigorous physical activity (MVPA) and sedentary behaviour (SB). This study aimed to investigate by means of Global Positioning System (GPS) and accelerometry whether locations where children engage in MVPA and SB differ by neighbourhood SES.MethodsParticipants included 83 children aged 7–9 from nine public schools located in a low- and high-SES area in Zurich, Switzerland. Children wore an accelerometer and GPS sensor for seven consecutive days. Time-matched accelerometer and GPS data was mapped with a geographic information system and each data point assigned to one of eight activity settings. The amount and proportion of MVPA and SB were calculated for every setting. To investigate differences between the two SES groups, multilevel analyses accounting for the hierarchical structure of the data were conducted.ResultsBoth SES groups achieved most minutes in MVPA at own school, on streets and at home and recorded the highest proportions of MVPA in recreational facilities, streets and other schools. The highest amounts and proportions of SB were found at home and own school. High-SES children accumulated significantly more minutes in MVPA and SB in parks, sport facilities, other schools and streets, while the low-SES group spent more time in both activities in other places. When taking the total time spent in a setting into account and using the proportion of MVPA or SB, the only differences between the two groups were found at other schools and outside, where the high-SES children showed a significantly higher activity level (p-values <0.001).ConclusionsSeveral differences in the spatial activity pattern between children from low- and high-SES neighbourhoods were found, independent of their individual SES. The findings seem to highlight the importance of providing safe streets and access to appropriate types of recreational facilities to reach recommended PA levels. Further policies to reduce SB within home and school environment are needed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-2954-8) contains supplementary material, which is available to authorized users.

Intentional harms are typically judged to be less forgivable than accidental harms.This difference depends on mental state reasoning (i.e., reasoning about beliefs and intentions), supported by a group of brain regions, the 'theory of mind' network.Prior research has found that (i) interfering with activity in this network can shift moral judgments away from reliance on mental state information, and (ii) high-functioning individuals with Autism Spectrum Disorder (ASD) rely significantly less on mental state information to make moral judgments than matched neurotypical (NT) participants.Across three experiments, we find using multi-voxel pattern analysis (MVPA) that, in NT adults, (i) one key region of the ToM network, the RTPJ, shows reliable and distinct spatial patterns of responses across voxels for intentional versus accidental harms, and (ii) individual differences in this neural pattern predict individual differences in moral judgment.By contrast, (iii) in ASD adults, the difference between intentional and accidental harms is not encoded in the voxelwise pattern in the RTPJ or any other region, and (iv) higher symptom severity scores are predictive of diminished pattern discriminability.We conclude that MVPA can detect features of mental state representations and that these features are behaviorally and clinically relevant.

The evolution of spatial patterns of brain activity during development and their role in the functional specialization of brain networks.

The human hand is capable of producing versatile yet precise movements largely owing to the complex neuromuscular systems that control our finger movement. This study seeks to quantify the spatial activation patterns of the forearm flexor muscles during individualized finger flexions. High-density (HD) surface electromyogram (sEMG) signals of forearm flexor muscles were obtained, and individual motor units were decomposed from the sEMG. Both macro-level spatial patterns of EMG activity and micro-level motor unit distributions were used to systematically characterize the forearm flexor activation patterns. Different features capturing the spatial patterns were extracted, and the unique patterns of forearm flexor activation were then quantified using pattern recognition approaches. We found that the forearm flexor spatial activation during the ring finger flexion was mostly distinct from other fingers, whereas the activation patterns of the middle finger were least distinguishable. However, all the different activation patterns can still be classified in high accuracy (94-100%) using pattern recognition. Our findings indicate that the partial overlapping of neural activation can limit accurate identification of specific finger movement based on limited recordings and sEMG features, and that HD sEMG recordings capturing detailed spatial activation patterns at both macro- and micro-levels are needed.

BackgroundSuccessful cooperation depends on reliable identification of friends and foes. Social insects discriminate colony members (nestmates/friends) from foreign workers (non-nestmates/foes) by colony-specific, multi-component colony odors. Traditionally, complex processing in the brain has been regarded as crucial for colony recognition. Odor information is represented as spatial patterns of activity and processed in the primary olfactory neuropile, the antennal lobe (AL) of insects, which is analogous to the vertebrate olfactory bulb. Correlative evidence indicates that the spatial activity patterns reflect odor-quality, i.e., how an odor is perceived. For colony odors, alternatively, a sensory filter in the peripheral nervous system was suggested, causing specific anosmia to nestmate colony odors. Here, we investigate neuronal correlates of colony odors in the brain of a social insect to directly test whether they are anosmic to nestmate colony odors and whether spatial activity patterns in the AL can predict how odor qualities like “friend” and “foe” are attributed to colony odors.Methodology/Principal FindingsUsing ant dummies that mimic natural conditions, we presented colony odors and investigated their neuronal representation in the ant Camponotus floridanus. Nestmate and non-nestmate colony odors elicited neuronal activity: In the periphery, we recorded sensory responses of olfactory receptor neurons (electroantennography), and in the brain, we measured colony odor specific spatial activity patterns in the AL (calcium imaging). Surprisingly, upon repeated stimulation with the same colony odor, spatial activity patterns were variable, and as variable as activity patterns elicited by different colony odors.ConclusionsAnts are not anosmic to nestmate colony odors. However, spatial activity patterns in the AL alone do not provide sufficient information for colony odor discrimination and this finding challenges the current notion of how odor quality is coded. Our result illustrates the enormous challenge for the nervous system to classify multi-component odors and indicates that other neuronal parameters, e.g., precise timing of neuronal activity, are likely necessary for attribution of odor quality to multi-component odors.

Spatial patterns of intrinsic neural activity in depressed patients with vascular risk factors as revealed by the amplitude of low-frequency fluctuation

Polarity-dependent orientation illusions: Review, model, and simulations

The association between spatial patterns of retail activity and the spatial configuration of street networks was examined by means of the space syntax methodology in eight Israeli cities that represent two city types, characterized by different planning approaches and urban growth: (i) new towns, which were established according to a comprehensive city plan and modern planning concepts of “tree-like” hierarchical street networks and “neighborhood units”; (ii) older cities, where street networks and the spatial patterns of retail activity were formed incrementally during their growth. Unlike in older cities, retail activity in new towns concentrates in relatively less-accessible and intermediate locations. This is indicated by a weak correlation between retail activity and the street network’s Integration and Choice centrality measures. The comparison between Israeli cities illustrates the influence of urban growth and planning approaches on the formation of retail activity and its interaction with the structure of the street network.

We used Magnetoencephalography (MEG) in combination with Representational Similarity Analysis to probe neural activity associated with distinct, item-specific lexico-semantic predictions during language comprehension. MEG activity was measured as participants read highly constraining sentences in which the final words could be predicted. Before the onset of the predicted words, both the spatial and temporal patterns of brain activity were more similar when the same words were predicted than when different words were predicted. The temporal patterns localized to the left inferior and medial temporal lobe. These findings provide evidence that unique spatial and temporal patterns of neural activity are associated with item-specific lexico-semantic predictions. We suggest that the unique spatial patterns reflected the prediction of spatially distributed semantic features associated with the predicted word, and that the left inferior/medial temporal lobe played a role in temporally 'binding' these features, giving rise to unique lexico-semantic predictions.

Objectives As one of the most objectionable sequelae of facial paralysis, patients with facial synkinesis are more likely to be depressed and have lower quality of life than other facial paralysis patients. However, there is no research on the spatial patterns of intrinsic brain activity and functional connectivity in these patients. The objective of this study was to investigate the spatial patterns and cerebral plasticity of facial synkinesis patients. Methods A total of 20 facial synkinesis patients (18 men and 2 women; mean age: 33.35 ± 6.97 years old) and 19 healthy controls (17 men and 2 women; mean age: 33.21 ± 6.75 years old) were enrolled in this study. resting-state functional magnetic resonance imaging (rs-fMRI) data were collected, and the amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC) were calculated for each participant. Two-sample t-tests were performed to compare the ALFF, ReHo, and DC maps between the two groups. Results Compared with the healthy controls, facial synkinesis patients exhibited decreased ALFF in the fusiform gyrus, lingual gyrus, parahippocampal gyrus, triangular inferior frontal gyrus, precentral gyrus, postcentral gyrus, cingulate gyrus, superior frontal gyrus, precuneus, caudate nucleus and thalamus; decreased ReHo in the cingulate gyrus, superior frontal gyrus, insula, superior temporal gyrus, orbital middle frontal gyrus, caudate nucleus and thalamus; and decreased DC in the frontal lobe, insula, cingulate gyrus, superior temporal gyrus, lenticular putamen, hippocampus and parahippocampal gyrus. We found significant overlap in the superior frontal gyrus across the ALFF, ReHo and DC analyses. Conclusions In facial synkinesis patients, the neurological activity in brain areas is reduced and the local synchronization in motion-related brain regions is decreased. The superior frontal gyrus could be a crucial region in the unique spatial patterns of intrinsic brain activity and functional connectivity in these patients.

It has been proposed that people can generate probabilistic predictions at multiple levels of representation during language comprehension. We used magnetoencephalography (MEG) and electroencephalography (EEG), in combination with representational similarity analysis, to seek neural evidence for the prediction of animacy features. In two studies, MEG and EEG activity was measured as human participants (both sexes) read three-sentence scenarios. Verbs in the final sentences constrained for either animate or inanimate semantic features of upcoming nouns, and the broader discourse context constrained for either a specific noun or for multiple nouns belonging to the same animacy category. We quantified the similarity between spatial patterns of brain activity following the verbs until just before the presentation of the nouns. The MEG and EEG datasets revealed converging evidence that the similarity between spatial patterns of neural activity following animate-constraining verbs was greater than following inanimate-constraining verbs. This effect could not be explained by lexical-semantic processing of the verbs themselves. We therefore suggest that it reflected the inherent difference in the semantic similarity structure of the predicted animate and inanimate nouns. Moreover, the effect was present regardless of whether a specific word could be predicted, providing strong evidence for the prediction of coarse-grained semantic features that goes beyond the prediction of individual words.SIGNIFICANCE STATEMENT Language inputs unfold very quickly during real-time communication. By predicting ahead, we can give our brains a "head start," so that language comprehension is faster and more efficient. Although most contexts do not constrain strongly for a specific word, they do allow us to predict some upcoming information. For example, following the context of "they cautioned the…," we can predict that the next word will be animate rather than inanimate (we can caution a person, but not an object). Here, we used EEG and MEG techniques to show that the brain is able to use these contextual constraints to predict the animacy of upcoming words during sentence comprehension, and that these predictions are associated with specific spatial patterns of neural activity.

We used Magnetoencephalography (MEG) in combination with Representational Similarity Analysis to probe neural activity associated with distinct, item-specific lexico-semantic predictions during language comprehension. MEG activity was measured as participants read highly constraining sentences in which the final words could be predicted. Before the onset of the predicted words, both the spatial and temporal patterns of brain activity were more similar when the same words were predicted than when different words were predicted. The temporal patterns localized to the left inferior and medial temporal lobe. These findings provide evidence that unique spatial and temporal patterns of neural activity are associated with item-specific lexico-semantic predictions. We suggest that the unique spatial patterns reflected the prediction of spatially distributed semantic features associated with the predicted word, and that the left inferior/medial temporal lobe played a role in temporally ‘binding’ these features, giving rise to unique lexico-semantic predictions.