5 research outputs found
A multimodal approach to studying visual-somatosensory integration in autism
No full textAutism is a neurodevelopmental condition characterized by differences in social communication as well as narrow, repetitive actions and interests. Over time, there has been increasing recognition of the prevalence and importance of sensory differences in autism, but there is a high degree of variability in how these sensory symptoms manifest both between and within individuals on the autism spectrum. Both hyper-sensitivity and hypo-sensitivity are common, and autistic people often seek out self-generated sensations while avoiding externally-generated sensations. In this dissertation, we focused specifically on the intersection of vision and somatosensation, the senses that drive interactions with the physical world. We began by reviewing the literature on visual-somatosensory integration across temporal, spatial, motor, and social domains. Establishing that there are many gaps in the understanding of atypical visual-somatosensory processing in autism, we assembled the experimental components to begin examining the neurophysiology behind self-stimulatory behaviors in autism. The first study (Chapter 2) employed virtual reality (VR) to create an artificial visual environment that allowed for the manipulation of visual cues during a reaching task. By removing visual indicators of the locations of the hands or reaching targets, we measured reaching accuracy while participants were constrained to utilizing proprioception or memory, without the addition of visual feedback. We then switched modalities to electroencephalography (EEG), where we used a haptic feedback device to assess somatosensory temporal processing in adults with autism (Chapter 3). A mismatch negativity (MMN) paradigm was used to assess sensitivity to unpredictable deviations in stimulus durations. Finally, we combined VR and EEG to create an experiment that probed the neural correlates of self-initiated and externally-initiated visual-somatosensory sensations (Chapter 4). This project assessed how the volition and predictability of tactile stimulation influenced the associated neurophysiological responses. To our knowledge, this study was the first to directly measure the cortical activity associated with self-generated somatosensation in autism. The collective work of this dissertation contributes to the broader literature on visual-somatosensory processing in autism and provides a foundation for future work on self-stimulatory behaviors in this population
Adults on the autism spectrum differ from neurotypical peers when self-generating but not passively-experiencing somatosensation: a high-density electrophysiological (EEG) mapping and virtual reality study
No full textLittle is known about how different features of tactile inputs affect somatosensory perception in autism. In this study we combined high-density electroencephalography (EEG) and virtual reality (VR) to assess how the volition and pattern consistency of somatosensory stimulation influenced the electrophysiological responses in neurotypical (n = 30) and autistic (n = 30) adults. Specifically, we compared N1 and P300 amplitudes when vibrotactile stimulation were actively triggered by self-motion (Active) versus passively triggered by target-motion (Passive). We also measured the mismatch negativity (MMN) to assess how deviations in the pattern of stimulus duration affected the electrophysiological responses. We observed comparable responses regardless of pattern deviation in the MMN time window between groups, but different patterns of amplitude in this time frame based on whether the stimulation was Active or Passive. In the autism group we observed smaller N1 amplitudes in response to Passive, but not Active, vibrations as compared to the control group. Conversely, there were overall larger magnitude P300 amplitudes in the autism group, but comparable levels of Passive-to-Active attenuation between groups. Overall, the autism cohort demonstrated variation from the neurotypical cohort with respect to the volition of the stimuli, but there were comparable results between groups in response to pattern deviation. These findings suggest that there are subtle differences in how adults with and without autism handle self-generated and externally-generated somatosensory sensations
Investigating Motor Preparation in Autism Spectrum Disorder with and without Attention Deficit/Hyperactivity Disorder
No full textAutism spectrum disorder (ASD) is a neurodevelopmental disorder, where motor impairments are common and impact individuals across the lifespan. A growing body of work suggests that alterations in predictive processes may contribute to the ASD symptomatology, such that the anticipation of upcoming events is disrupted. Such an alteration could potentially impact motor planning. Motor planning deficits are not, however, unique to ASD. Attention-deficit/hyperactivity disorder (ADHD) has been linked to motor planning and execution difficulties, and ADHD commonly co-occurs with ASD. Whether motor planning deficits are characteristic of ASD broadly or magnified in the context of co-morbid ADHD is unclear. In this study we examined the lateralized readiness potential (LRP) to assess motor preparation and action-consequence prediction. While electroencephalography (EEG) was recorded, 29 typically developing (TD) controls and 21 ASD children both with (ASD+ADHD; n=12) and without (ASD−ADHD; n=9) comorbid ADHD completed a paradigm wherein voluntary actions either did or did not result in an auditory consequence. Our results revealed differences in LRP amplitude as a function of group and whether an action produced an effect. In TD, LRP amplitude was attenuated when an action produced an effect versus when it did not. In contrast, the ASD−ADHD group demonstrated LRP enhancement when the action led to an effect. Finally, the ASD+ADHD had attenuated LRP responses compared to other groups regardless of action-effect pairings. These findings suggest that the neural mechanisms for motor preparation and prediction differ between ASD and TD, and are influenced by the presence or absence of ADHD comorbidity
Social visual attentional engagement and memory in Phelan-McDermid syndrome and autism spectrum disorder: a pilot eye tracking study
No full textBackground
The current study used eye tracking to investigate attention and recognition memory in Phelan-McDermid syndrome (PMS), a rare genetic disorder characterized by intellectual disability, motor delays, and a high likelihood of comorbid autism spectrum disorder (ASD). Social deficits represent a core feature of ASD, including decreased propensity to orient to or show preference for social stimuli.
Methods
We used a visual paired-comparison task with both social and non-social images, assessing looking behavior to a novel image versus a previously viewed familiar image to characterize social attention and recognition memory in PMS (n = 22), idiopathic ASD (iASD, n = 38), and typically developing (TD) controls (n = 26). The idiopathic ASD cohort was divided into subgroups with intellectual disabilities (ID; developmental quotient 70) and the PMS group into those with and without a co-morbid ASD diagnosis.
Results
On measures of attention, the PMS group with a comorbid ASD diagnosis spent less time viewing the social images compared to non-social images; the rate of looking back and forth between images was lowest in the iASD with ID group. Furthermore, while all groups demonstrated intact recognition memory when novel non-social stimuli were initially presented (pre-switch), participants with PMS showed no preference during the post-switch memory presentation. In iASD, the group without ID, but not the group with ID, showed a novelty preference for social stimuli. Across indices, individuals with PMS and ASD performed more similarly to PMS without ASD and less similarly to the iASD group.
Conclusion
These findings demonstrate further evidence of differences in attention and memory for social stimuli in ASD and provide contrasts between iASD and PMS
Directorio de consultores, recursos y sitios de Internet relacionados con bibliotecas mexicanas = Directory of consultants, resources & Internet sites relating to Mexican libraries
No full textThis guidebook was compiled for: 1) foreign librarians, 2) Mexican students enrolled in programs of study in the field of librarianship or in certificate programs in library science, 3) volunteers or those in practicum service, 4) paraprofessionals or the recently degreed Mexican librarian, 5) non-experts. This work, a bilingual annotated directory, contains basic information on a wide range of resources relevant to librarianship as presently practiced in Mexico: books, articles, useful web pages, events, possible contacts in institutions. To find specific phrases or words use your navigator’s BUSCAR/FIND search tool, or scroll down. There is no intention to publish the list at this time. The information is being provided as a free service. This directory database is not exhaustive; the user is encouraged to verify all data from the source. Please provide us with your opinion concerning this Directory. All additions, suggestions, or modifications will be welcome. To contact the compiler, email: William Abrams Indexing Services, [email protected] . Your comments will help us to improve future editions. Terms of Use: This Directory is not copyrighted. It is a document in the public domain. No rights are reserved, either for the original or for derivative works. The file may be freely copied without prior permission, preferably using a CD-ROM data disc (but if access is from the website, one should first verify that the download has completed before copying). (Abstract taken verbatim from author's)
