Audiovisual sensory processing in autism spectrum condition.

Autism spectrum condition (ASC) consists of a set of pervasive developmental problems marked by measurable deficits in social interaction and communication, often coupled with specific and repetitive patterns of behavior. Featured restrictions in the capability to communicate and remain attentive can directly relate to the individual’s ability to interact with others within societal norms. Evidence has suggested that the deficits commonly demonstrated by individuals with autism may arise from a disconnect between neural processes governing sensory inputs. Comparing ASC subjects to controls, previous investigations had shown that electroencephalogram (EEG) recordings and event-related potentials (ERPs) evoked via separate auditory and visual stimuli do not display aberrations in latency or amplitude in the ASC individuals. However, the findings reported here suggest decreased latencies in early-evoked potentials. Additionally, during the combined audiovisual task, electrophysiological recordings revealed significant cortical activity differences between ASC subjects and controls. To investigate the aforementioned phenomena this study employed EEG recording technology while subjects participated in an oddball-paradigm reaction time test. This project reports on the differences behavioral reactions as well as variances in amplitude and latency in twelve autistic individuals and twelve matched controls. Subjects were evaluated using the event related potentials, N100, N200, and P300, as well as dipole source coherence and power of EEG gamma oscillations recorded at fronto-central and parietal sites in both hemispheres. Findings of this study suggest that the irregularities arise from deficits in the integration and combinatorial processing of multiple sensory inputs. Previous research investigating the neuropathology of autism has identified abnormalities in the structure, number and activity of the cortical minicolumns, which are believed to influence excitatory and inhibitory impulses of sensory processing. The minicolumns of ASC individuals appear in greater number coupled with increased neuronal density due to a reduction in the volume of peripheral neuropil space and neuronal cell bodies. Such a cortical and cellular arrangement favors the formation of short intralobular connections between neurons at the expense of longer interlobular fibers. This study proposes that aberrations in sensory processing and functional cortical binding, as evidenced by EEG recordings related to the tasks, further reflect underlying abnormalities of minicolumns in ASC individuals. Thus, the results of this project intuitively suggest that dysfunction of sensory processing by way of minicolumn irregularity may in turn lead to symptoms commonly associated with autism spectrum condition

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Self-directedness, integration and higher cognition

In this paper I discuss connections between self-directedness, integration and higher cognition. I present a model of self-directedness as a basis for approaching higher cognition from a situated cognition perspective. According to this model increases in sensorimotor complexity create pressure for integrative higher order control and learning processes for acquiring information about the context in which action occurs. This generates complex articulated abstractive information processing, which forms the major basis for higher cognition. I present evidence that indicates that the same integrative characteristics found in lower cognitive process such as motor adaptation are present in a range of higher cognitive process, including conceptual learning. This account helps explain situated cognition phenomena in humans because the integrative processes by which the brain adapts to control interaction are relatively agnostic concerning the source of the structure participating in the process. Thus, from the perspective of the motor control system using a tool is not fundamentally different to simply controlling an arm

The sound of actions: a mismatch negativity (MMN) study

The ability to derive the intentions of others from the sound produced by their actions is quintessential to effective social behaviour. Many neuroscientists believe that this ability depends on the brain’s mirror-neuron system, which provides a direct link between action and perception. Precisely how intentions can be inferred through actionperception, however, has provoked much debate. One challenge in inferring the cause of a perceived action, is the fact that the problem is ill-posed, because identical movements can be made to perform different actions with different goals. Here, we show how, in the auditory modality, identification of most likely cause of a human action-related sound is highly subject to inferences. Using multi-channel, event-related potentials (ERPs), we determined the temporal dynamics of the ability to decipher action sounds by recording the mismatch negativity (MMN) generated in response to multi-deviant stimuli consisting of 3 different human action-related sounds (click of the tongue, hand clapping, and footsteps) and a non-human action-related sound (water drop). Subjects listened to the original sound-stimulus and to sounds obtained by altering 1 (low degree of disguise) or more complex (high degree of disguise) acoustic parameters of the original sound

Models of atypical development must also be models of normal development

Functional magnetic resonance imaging studies of developmental disorders and normal cognition that include children are becoming increasingly common and represent part of a newly expanding field of developmental cognitive neuroscience. These studies have illustrated the importance of the process of development in understanding brain mechanisms underlying cognition and including children ill the study of the etiology of developmental disorders

Are developmental disorders like cases of adult brain damage? Implications from connectionist modelling

It is often assumed that similar domain-specific behavioural impairments found in cases of adult brain damage and developmental disorders correspond to similar underlying causes, and can serve as convergent evidence for the modular structure of the normal adult cognitive system. We argue that this correspondence is contingent on an unsupported assumption that atypical development can produce selective deficits while the rest of the system develops normally (Residual Normality), and that this assumption tends to bias data collection in the field. Based on a review of connectionist models of acquired and developmental disorders in the domains of reading and past tense, as well as on new simulations, we explore the computational viability of Residual Normality and the potential role of development in producing behavioural deficits. Simulations demonstrate that damage to a developmental model can produce very different effects depending on whether it occurs prior to or following the training process. Because developmental disorders typically involve damage prior to learning, we conclude that the developmental process is a key component of the explanation of endstate impairments in such disorders. Further simulations demonstrate that in simple connectionist learning systems, the assumption of Residual Normality is undermined by processes of compensation or alteration elsewhere in the system. We outline the precise computational conditions required for Residual Normality to hold in development, and suggest that in many cases it is an unlikely hypothesis. We conclude that in developmental disorders, inferences from behavioural deficits to underlying structure crucially depend on developmental conditions, and that the process of ontogenetic development cannot be ignored in constructing models of developmental disorders