Despite numerous reports of abnormalities in limb motor controls in spatial orientation in individuals with autism spectrum disorder (ASD), the underlying mechanisms have not been elucidated. We ...studied the influence of allocentric coordinates on ongoing reaching movements, which has been reported to strongly affect the reaching movements of typically developing (TD) individuals. ASD and TD participants observed a target presented randomly on one of the four corners of a frame on a screen. After it disappeared, another frame was presented slightly shifted leftward/rightward. The participants touched the memorized position of the target relatively congruent with a reference frame (allocentric condition) or ignoring it (egocentric condition). Results suggested that TD individuals were apt to touch the positions in allocentric manner rather than egocentric manner, while ASDs did not show this prioritization. Our findings demonstrate that decreased utilization of visual landmarks in ongoing movement may underlie motor disabilities in autism.
Atypical processing of stimulus inputs across a range of sensory modalities in autism spectrum disorder (ASD) is widely reported. Sensory processing is known to be influenced by bodily internal ...states such as physiological arousal and anxiety. As a sizeable proportion of ASD reportedly have co‐morbid anxiety disorders that are linked with dysregulated arousal, we investigated if face emotion arousal cues influenced visual sensory sensitivity (indexed by temporal resolution) in ASD (n = 20) compared to a matched group of typically developed individuals (TD, n = 21). We asked further if emotion‐cued changes in visual sensitivity were associated with individual differences in state and trait anxiety. Participants reported the laterality of the second of two consecutive Gaussian‐blob flashes in a visual temporal order judgment task (v‐TOJ), demanding higher‐level visual processing. The key manipulation was presenting a task‐irrelevant face emotion cue briefly at unexpected time points preceding the task‐relevant flashes. Disgust vs. Neutral emotion signals significantly enhanced the visual temporal resolution in ASD. Individual state‐anxiety scores showed a fair correlative trend with the emotion‐cued changes in temporal resolution (Disgust versus Neutral) in ASD but missed statistical significance. Both these effects were absent in TD. The results show that individual state‐anxiety levels likely modulate the effect of emotions on visual temporal sensitivity in ASD. The findings support a nuanced approach to understand the disparate sensory features in ASD, by factoring in the interplay of the individual reactivity to environmental affective information and the severity of anxiety.
Disgust vs. Neutral facial emotion cues enhanced visual temporal resolution (TR) in autism spectrum disorder (ASD). Emotion‐induced TR change in ASD seemed to suggest an association with their subjective state‐anxiety. Temporally unexpected affective cues may influence higher‐order visual sensory processes in ASD, which could be conditioned by individual state‐anxiety levels.
Several motor disabilities accompanied with autism spectrum disorder (ASD) are widely known despite limited reports of underlying neural mechanisms. Gamma-aminobutyric acid (GABA) levels in the ...motor-related cortical areas modulate several motor performances in healthy participants. We hypothesized that abnormal GABA concentrations in the primary motor area (M1) and supplementary motor area (SMA) associate with different motor difficulties for ASD adolescents/adults. We found that increased GABA concentrations in M1 measured using
1
H-magnetic resonance spectroscopy exhibited lower motor performance in tasks requiring increased muscle strength while lower GABA concentrations in SMA were associated with lower scores in tests measuring body coordination. The degrees of neural inhibition in the M1 and SMA regions would contribute to different dimensions of motor disabilities in autism.
Individuals with autism spectrum disorder (ASD) often exhibit abnormal processing of sensory inputs from multiple modalities and higher-order cognitive/behavioral response to those inputs. Several ...lines of evidence suggest that altered γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the brain, is a central characteristic of the neurophysiology of ASD. The relationship between GABA in particular brain regions and atypical sensory processing in ASD is poorly understood. We therefore employed 1H magnetic resonance spectroscopy (1H-MRS) to examine whether GABA levels in brain regions critical to higher-order motor and/or multiple sensory functions were associated with abnormal sensory responses in ASD. We evaluated atypical sensory processing with a clinically-validated assessment tool. Furthermore, we measured GABA levels in four regions: one each in the primary visual cortex, the left sensorimotor cortex, the left supplementary motor area (SMA), and the ventral premotor cortex (vPMC). These regions are thought to be involved in executing and coordinating cognitive and behavioral functions in response to multisensory inputs. We found sensory hyper-responsiveness in ASD relative to control participants. We also found reduced GABA concentrations in the left SMA but no differences in other regions of interest between ASD and control participants. A correlation analysis revealed a negative association between left vPMC GABA and the severity of sensory hyper-responsiveness across all participants, and the independent ASD group. These findings suggest that reduced inhibitory neurotransmission (reduced GABA) in a higher-order motor area, which modulates motor commands and integrates multiple sensory modalities, may underlie sensory hyper-responsiveness in ASD.
Understanding the intentions of others is crucial in developing positive social relationships. Comparative human and non-human animal studies have addressed the phylogenetic origin of this ability. ...However, few studies have explored the importance of motion information in distinguishing others’ intentions and goals in non-human primates. This study addressed whether squirrel monkeys (
Saimiri sciureus
) are able to perceive a goal-directed motion pattern—specifically, chasing—represented by two geometric objects. In Experiment 1, we trained squirrel monkeys to discriminate a “Chasing” sequence from a “Random” sequence. We then confirmed that this discrimination transferred to new stimuli (“Chasing” and “Random”) in a probe test. To determine whether the monkeys used similarities of trajectory to discriminate chasing from random motion, we also presented a non-chasing “Clone” sequence in which the trajectories of the two figures were identical. Three of six monkeys were able to discriminate “Chasing” from the other sequences. In Experiment 2, we confirmed humans’ recognition of chasing with the stimuli from Experiment 1. In Experiment 3, the three monkeys for which discrimination did not transfer to the new stimuli in Experiment 1 were trained to discriminate between “Chasing” and “Clone” sequences. At testing, all three monkeys had learned to discriminate chasing, and two transferred their learning to new stimuli. Our results suggest that squirrel monkeys use goal-directed motion patterns, rather than simply similarity of trajectory, to discriminate chasing. Further investigation is necessary to identify the motion characteristics that contribute to this discrimination.
Abstract
Body ownership is a fundamental aspect of self-consciousness. Illusion of body ownership is caused by updating body representation through multisensory integration. Synchronous visuotactile ...stimulation of a hand and rubber hand leads to illusory changes in body ownership in humans, but this is impaired in individuals with autism spectrum disorder (ASD). We previously reported that mice also exhibit body ownership illusion. With synchronous stroking of a tail and rubber tail, mice responded as if their own tails were being touched when the rubber tails were grasped (‘rubber tail illusion’). However, it remains unknown whether deficits in illusion of body ownership occur in mouse models of autism. Here, we examined whether the ‘rubber tail illusion’ occurred in
Ca
2+
-dependent activator protein for secretion
2
-
knockout (
Caps2
-KO) mice, which exhibit autistic-like phenotypes. During the synchronous stroking, response rates were significantly lower in
Caps2
-KO mice than in wild-type mice. There were no significant differences between the response rates of wild-type and
Caps2
-KO mice during the asynchronous stroking. The ‘rubber tail illusion’ was weak in
Caps2
-KO mice, suggesting that
Caps2
-KO mice experienced weaker visuotactile integration during the task. The rubber tail task will be a useful tool in mouse models of autism to evaluate atypical sensory processing.
In humans, attentional biases have been shown to negative (dangerous animals, physical threat) and positive (high caloric food, alcohol) stimuli. However, it is not clear whether these attentional ...biases reflect on stimulus driven, bottom up, or goal driven, top down, attentional processes. Here we show that, like humans, Japanese macaques show an attentional bias to snakes in a dot probe task (Experiment 1). Moreover, this attentional bias reflects on bottom up driven, preferential engagement of attention by snake images (Experiment 2a), a finding that was replicated in a study that used the same methodology in humans (Experiment 2b). These results are consistent with the notion that attentional bias to snakes reflects on an evolutionarily old, stimulus driven threat detection mechanism which is found in both species.
Recent translational studies using mice have contributed toward elucidating the neural, genetic, and molecular basis of social communication deficits. Nevertheless, many components of visual ...processes underlying mice sociality remain unresolved, including perception of bodily-movement. Here, we aimed to reveal the visual sensitivity of mice to information on bodily motion using biological motion displays depicted by simple geometric dots. We introduced biological motions extracted from walking mice vs. corresponding meaningless scrambled motions, in which the spatial configurations of each path of dots were shuffled. The apparatus was a three-chambered box with an opening between the chambers, and each side chamber had a monitor. We measured the exploration time of mice within the apparatus during the test, with two types of displays being presented. Mice spent more time in the chamber with the scrambled motion displays, indicating that animals spontaneously discriminated stimuli, with the scrambled motion being relatively novel. Furthermore, mice might have detected socially familiar cues from the biological motion displays. Subsequent testing revealed that additional mice showed no bias to the static versions of the stimuli used in the Movie test. Thus, we confirmed that mice modulated their behavior by focusing on the motion information of the stimuli, rather than the spatial configurations of each dot. Our findings provide a new perspective on how visual processing contributes to underlying social behavior in mice, potentially facilitating future translational studies of social deficits with respect to genetic and neural bases.
Humans interpret others' goals based on motion information, and this capacity contributes to our mental reasoning. The present study sought to determine whether Japanese macaques (Macaca fuscata) ...perceive goal-directedness in chasing events depicted by two geometric particles. In Experiment 1, two monkeys and adult humans were trained to discriminate between Chasing and Random sequences. We then introduced probe stimuli with various levels of correlation between the particle trajectories to examine whether participants performed the task using higher correlation. Participants chose stimuli with the highest correlations by chance, suggesting that correlations were not the discriminative cue. Experiment 2 examined whether participants focused on particle proximity. Participants differentiated between Chasing and Control sequences; the distance between two particles was identical in both. Results indicated that, like humans, the Japanese macaques did not use physical cues alone to perform the discrimination task and integrated the cues spontaneously. This suggests that goal attribution resulting from motion information is a widespread cognitive phenotype in primate species.
The human brain is sensitive to incoming sensory information across multiple time scales. Temporal scales of information represented in the brain generally constrain behavior. Despite reports of the ...neural correlates of millisecond timing, how the human brain processes sensory stimuli in the sub-second range (≤100 ms) and its behavioral implications are areas of active scientific inquiry. An autism spectrum disorder (ASD) patient showed a tactile discrimination threshold of 6.49 ms on a temporal order judgment (TOJ) task which was approximately 10-fold superior than other ASD and healthy controls (59 and 69 ms, respectively). To investigate the brain regions of this extremely high temporal resolution in the patient, we used functional magnetic resonance imaging (fMRI) during TOJ. We observed greater activity notably in the left superior temporal gyrus (STG) and precentral gyrus (PrG) compared to that of controls. Generally, the left superior frontal gyrus (SFG) correlated positively, while the opercular part of right inferior frontal gyrus (IFG) correlated negatively, with the correct TOJ rate across all subjects (the patient + 22 healthy controls). We found that the performance was negatively correlated with the strength of neural responses in the right IFG overall in 30 participants (the patient + 22 healthy and 7 ASD controls). Our data reveal superior ability of this particular case of ASD in the millisecond scale for sensory inputs. We highlight several neural correlates of TOJ underlying the facilitation and/or inhibition of temporal resolution in humans.
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