Electrodermal reactivity to emotion processing in adults with autistic spectrum disorders.

Although alterations of emotion processing are recognized as a core component of autism, the level at which alterations occur is still debated. Discrepant results suggest that overt assessment of emotion processing is not appropriate. In this study, skin conductance response (SCR) was used to examine covert emotional processes. Both behavioural responses and SCRs of 16 adults with an autistic spectrum disorder (ASD) were compared to those of 16 typical matched adults. Participants had to judge emotional facial expressions, the age of faces or the direction of a moving object. Although behavioural performance was similar in the two populations, individuals with an ASD exhibited lower SCRs than controls in the emotional judgement task. This suggests that such individuals may rely on different strategies due to altered autonomic processing. Furthermore, failure to produce normal physiological reactions to emotional faces may be related to social impairments in individuals with an ASD.

Current knowledge in moral cognition can improve medical ethics.

Physicians frequently face ethical dilemmas when caring for patients. To help them to cope with these, biomedical ethics aims to implement moral norms for particular problems and contexts. As a means of studying the cognitive and neurobiological features underlying the respect for these norms, moral cognitive neuroscience could help us to understand and improve ethical questioning. The article reviews recent developments in the field and presents neurobiological arguments to highlight why some moral rules are universally shared and why some ethical responses are very dependent on context.

Normal basilar artery structure and biaxial mechanical behaviour.

Much is known about cerebral vasospasm, a devastating sequela to ruptured intracranial aneurysms, yet underlying mechanisms remain unclear and clinical treatments have proven unsatisfactory. We have hypothesised that biochemical stimuli associated with the formation of extravascular blood clots dominate early maladaptive responses, leading to marked structural and functional changes in affected cerebral arteries. Before a precise picture of vasospasm can be obtained, however, we must understand better the structure and mechanical behaviour of normal cerebral arteries. Basilar arteries from rabbits were tested mechanically under biaxial loading conditions with and without active tone, segments were imaged using intravital nonlinear optical microscopy to quantify transmural orientations of fibrillar collagen, and passive mechanical data were fit with a four-fiber family stress-stretch relation. This constitutive model predicted well the overall mechanical behaviour and mean collagen fiber distributions, and thereby has promise to contribute to analyses of the biochemomechanics of cerebral vasospasm and similar cerebral pathologies. It is now time, therefore, to focus on mechanisms of vasospasm via mathematical models that incorporate growth and remodelling in terms of changes in the cross-linking and distributions of adventitial and medial collagen, primary contributors to the structural integrity of the arterial wall.

Brief report: recognition of emotional and non-emotional biological motion in individuals with autistic spectrum disorders.

This study aimed to explore the perception of different components of biological movement in individuals with autism and Asperger syndrome. The ability to recognize a person's actions, subjective states, emotions, and objects conveyed by moving point-light displays was assessed in 19 participants with autism and 19 comparable typical control participants. Results showed that the participants with autism were as able as controls to name point-light displays of non-human objects and human actions. In contrast, they were significantly poorer at labeling emotional displays, suggesting that they are specifically impaired in attending to emotional states. Most studies have highlighted an emotional deficit in facial expression perception; our results extend this hypothesized deficit to the perception and interpretation of whole-body biological movements.

fMRI investigation of visual change detection in adults with autism.

People with autism spectrum disorders (ASD) may show unusual reactions to unexpected changes that appear in their environment. Although several studies have highlighted atypical auditory change processing in ASD, little is known in this disorder about the brain processes involved in visual automatic change detection. The present fMRI study was designed to localize brain activity elicited by unexpected visual changing stimuli in adults with ASD compared to controls. Twelve patients with ASD and 17 healthy adults participated in the experiment in which subjects were presented with a visual oddball sequence while performing a concurrent target detection task. Combined results across participants highlight the involvement of both occipital (BA 18/19) and frontal (BA 6/8) regions during visual change detection. However, adults with ASD display greater activity in the bilateral occipital cortex and in the anterior cingulate cortex (ACC) associated with smaller activation in the superior and middle frontal gyri than controls. A psychophysiological interaction (PPI) analysis was performed with ACC as the seed region and revealed greater functionally connectivity to sensory regions in ASD than in controls, but less connectivity to prefrontal and orbito-frontal cortices. Thus, compared to controls, larger sensory activation associated with reduced frontal activation was seen in ASD during automatic visual change detection. Atypical psychophysiological interactions between frontal and occipital regions were also found, congruent with the idea of atypical connectivity between these regions in ASD. The atypical involvement of the ACC in visual change detection can be related to abnormalities previously observed in the auditory modality, thus supporting the hypothesis of an altered general mechanism of change detection in patients with ASD that would underlie their unusual reaction to change.

A failure to grasp the affective meaning of actions in autism spectrum disorder subjects.

The ability to grasp emotional messages in everyday gestures and respond to them is at the core of successful social communication. The hypothesis that abnormalities in socio-emotional behavior in people with autism are linked to a failure to grasp emotional significance conveyed by gestures was explored. We measured brain activity using fMRI during perception of fearful or neutral actions and showed that whereas similar activation of brain regions known to play a role in action perception was revealed in both autistics and controls, autistics failed to activate amygdala, inferior frontal gyrus and premotor cortex when viewing gestures expressing fear. Our results support the notion that dysfunctions in this network may contribute significantly to the characteristic communicative impairments documented in autism.

Negative emotion does not enhance recall skills in adults with autistic spectrum disorders.

Recent empirical findings suggest a significant influence of emotion on memory processes. Surprisingly, although emotion-processing difficulties appear to be a hallmark feature in autism spectrum disorders (ASD), their impact on higher-level cognitive functions, such as memory, has not been directly studied in this population. The aim of this study was to address this issue by assessing whether the emotional valence of visual scenes affects recall skills in high-functioning individuals with ASD. To this purpose, their recall performance of neutral and emotional pictures was compared with that of typically developing adults (control group). Results revealed that while typically developing individuals showed enhanced recall skills for negative relative to positive and neutral pictures, individuals with ASD recalled the neutral pictures as well as the emotional ones. Findings of this study thus point to reduced influence of emotion on memory processes in ASD than in typically developing individuals, possibly owing to amygdala dysfunctions.

The anthropomorphic brain: the mirror neuron system responds to human and robotic actions.

In humans and monkeys the mirror neuron system transforms seen actions into our inner representation of these actions. Here we asked if this system responds also if we see an industrial robot perform similar actions. We localised the motor areas involved in the execution of hand actions, presented the same subjects blocks of movies of humans or robots perform a variety of actions. The mirror system was activated strongly by the sight of both human and robotic actions, with no significant differences between these two agents. Finally we observed that seeing a robot perform a single action repeatedly within a block failed to activate the mirror system. This latter finding suggests that previous studies may have failed to find mirror activations to robotic actions because of the repetitiveness of the presented actions. Our findings suggest that the mirror neuron system could contribute to the understanding of a wider range of actions than previously assumed, and that the goal of an action might be more important for mirror activations than the way in which the action is performed.

Generalized least-squares method applied to fMRI time series with empirically determined correlation matrix.

Functional magnetic resonance imaging (fMRI) time series analysis and statistical inferences about the effect of a cognitive task on the regional cerebral blood flow (rCBF) are largely based on the linear model. However, this method requires that the error vector is a gaussian variable with an identity correlation matrix. When this assumption cannot be accepted, statistical inferences can be made using generalized least squares. In this case, knowledge of the covariance matrix of the error vector is needed. In the present report, we propose a method that needs stationarity of the autocorrelation function but is more flexible than autoregressive model of order p (AR(p)) models because it is not necessary to predefine a relation between coefficients of the correlation matrix. We tested this method on sets of simulated data (with presence of an effect of interest or not) representing a time series with a monotonically decreasing autocorrelation function. This time series mimicked an experiment using a random event-related design that does not create correlation between scans. The autocorrelation function is empirically determined and used to reconstitute the correlation matrix as the toeplitz matrix built from the autocorrelation function. When applied to simulated time series with no effect of interest, this method allows the determination of F values corresponding to the accurate false positive level. Moreover, when applied to time series with an effect of interest, this method gives a density function of F values which allows the rejection of the null hypothesis. This method provides a flexible but interpretable time domain noise model.

A comparison of a low ionic strength saline medium with routine methods for antibody detection.

Antibody detection studies were undertaken in order to compare a low ionic strength (LIS) medium with a conventional albumin-fortified isotonic medium. Tests were performed in parallel with both media at room temperature and at 37 C. A 30mM NaCl solution was used as the LIS medium and in this study this enhanced antibody reactions without causing nonspecific reactions. The LIS medium detected all of more than 50 Rh and more than 75 non-Rh antibodies after 15 minutes of incubation. Often 30 to 60 minutes of incubation were required to detect these antibodies by the routine method. Several antibodies that were detected with the LIS medium after 15 minutes of incubation were either undetected or had given a nonspecific pattern of activity after 60 minutes incubation in the routine medium. When an antibody was present, the LIS medium invariably gave stronger, more clear-cut results. It is concluded that the LIS medium is generally more sensitive than a conventional medium in detecting antibodies since such a medium will detect clinically significant antibodies after only 15 minutes incubation as well as detect antibodies missed by a conventional medium. An antibody detection system utilizing this medium has obvious applicability to a hospital transfusion service.

Brain regions involved in the perception of gaze: a PET study.

Mutual gaze may be described as a psychological process during which two persons have the feeling of a brief link between their two minds. In the monkey, specific cell assemblies in the superior temporal cortex of the brain are responsive to gaze. This suggests that the brain may have evolved mechanisms for interpreting direct eye contact. These mechanisms could depend on the activation of specific brain regions. Positron emission tomography was used to measure activity in brain regions in healthy volunteers while they were looking at faces featuring, respectively, eye contact, averted gaze, or no gaze. As expected a region known to be involved in face processing was found to be activated in the ventral occipito-temporal region, especially in the right hemisphere. Averted gaze and mutual gaze triggered blood flow responses in similar areas which were different from those involved in face processing. These areas included the occipital part of the fusiform gyrus, the right parietal lobule, the right inferior temporal gyrus, and the middle temporal gyrus in both hemispheres. These results are consistent with the hypothesis that perception of eyes regardless of the direction of the gaze is subserved by a distributed network. However, no conclusive evidence was found for specific area(s) devoted to mutual gaze processing.

Neural representation for the perception of the intentionality of actions.

A novel population of cells is described, located in the anterior part of the superior temporal sulcus (STSa, sometimes called STPa) of the temporal lobe in the macaque monkey. These cells respond selectively to the sight of reaching but only when the agent performing the action is seen to be attending to the target position of the reaching. We describe how such conditional selectivity can be generated from the properties of distinct cell populations within STSa. One cell population responds selectively to faces, eye gaze, and body posture, and we argue that subsets of these cells code for the direction of attention of others. A second cell population is selectively responsive to limb movement in certain directions (e.g., responding to an arm movement to the left but not to an equivalent leg movement or vice versa). The responses of a subset of cells sensitive to limb movement are modulated by the direction of attention (indicated by head and body posture of the agent performing the action). We conclude that this combined analysis of direction of attention and body movements supports the detection of intentional actions.

Neuronal representation of disappearing and hidden objects in temporal cortex of the macaque.

Neurons in the anterior regions of the banks of the superior temporal sulcus (STSa) of the macaque monkey respond to the sight of biologically significant stimuli such as faces, bodies and their motion. In this study the responses of STSa neurons were recorded during the gradual occlusion of the experimenter and other mobile objects behind screens at distances of 0.5-4 m from the monkeys. The experimenter or other object remained out of sight for 3-15 s before emerging back in to view. We describe a population of neurons (n=33) showing increased activity during the occlusion of objects that was maintained for up to 11 s following complete occlusion (when only the occluder itself was visible). This increase in activity was selective for the position of the occlusion within the testing room. Many neurons showed little or no change in activity prior to occlusion when the object or experimenter was completely in view. By coding for the presence and location of recently occluded objects, these responses may contribute to the perceptual capacity for object permanence.