Each cerebral hemisphere primarily controls and receives sensory input with regard to the contralateral hand. In the disconnected brain (split-brain), when the hands are uncrossed, direct visual access to each hand is available to the controlling (contralateral) hemisphere. However, when a hand crosses the midline, visual and tactile information regarding the hand are presented to different hemispheres. It is unknown how a contralateral hemi- sphere codes the position and orientation of a visually inaccessible hand in the discon- nected brain. The present work addresses this issue. We ask how each hemisphere represents “its” hand across hand positions that span the midline in the absence of cortical input from the contralateral hemisphere. In other words, when a hand is placed across the midline and is visually inaccessible, is it represented by the controlling hemisphere: (1) in accordance with its new position with respect to the body (e.g., a left hand “becomes” a right effector when it crosses the midline), (2) with left/right position information unal- tered (e.g., the left hand is represented as “left” regardless of its location), or (3) stripped of its location information altogether? The relationship between hand position and the spatial codes assigned to potential responses (an index of hand representation) was investigated in two split-brain patients using direct (Experiment 1) and orthogonal (Experiment 2) S-R compatibility paradigms. S-R compatibility effects in split-brain patients were consistent with those displayed by typical individuals. These findings suggest that position-based compatibility effects do not rely on cross-cortical connections. Rather, each hemisphere can accurately represent the full visuomotor space, a process that appears to be subserved by subcortical connections between the hemispheres.

The present study used a synchronization-continuation paradigm during continuous bimanual drumming with different cues in 17 persons with Down syndrome, eight typical persons with similar mental age and eight typical persons with similar chronological age. The task required participants to hit two drums with their hands at the same time following music (e.g., a tune with various decibel drum beats), auditory (e.g., sound of drumbeat), verbal (e.g., voice saying “drum”), and visual (e.g., video of both hands moving up and down and hitting the drums together) cues for 10 seconds, then continue drumming in the absence of cues for another 10 seconds. In general, when all groups were following the music cues their movements were faster as compared with their movements in the auditory, verbal, and visual conditions. In addition, when following visual cues all groups produced more accurate and consistently coordinated movements than with the other cue types. Further, participants with Down syndrome often stopped moving when the pacing cues were eliminated indicating a need for continuous cues for continuous movements.

According to action-centered models of attention, the patterns of distractor interference that emerge in selective reaching tasks are related to the time and effort required to resolve a race for activation between competing target and non-target response producing processes. Previous studies have only used unimanual aiming tasks and, as such, only examined the effects of competition that occurs within a limb. The results of studies using unimanual aiming movements often reveal an "ipsilateral effect"--distractors on the same side of space as the effector cause greater interference than distractors on the opposite side of space. The cost of the competition when response selection is between the limbs has yet to be addressed. Participants in the present study executed reaching movements to 1 of 4 (2 left, 2 right) possible target locations with and without a distractor. Participants made ipsilateral reaches (left hand to left targets, right hand to right targets). In contrast to studies using unimanual aiming movements, a "contralateral effect" was observed; distractors affording responses for the other hand (in contralateral space) caused more interference than distractors affording responses for the same hand. The findings from the present research demonstrate that when certain portions of response planning must be resolved prior to response initiation, distractors that code for that dimension cause the greatest interference.

Click to increase image sizeClick to decrease image size ACKNOWLEDGMENTS The authors thank editor Dr. Daniel Corcos for suggesting and facilitating this discussion. This research was supported through Discovery Grants, a Canadian Graduate Scholarship, and an Undergraduate Student Research Award from the Natural Sciences and Engineering Research Council of Canada as well as an Early Researcher Award from the Ontario Ministry of Research and Innovation.

ABSTRACT Numerous studies have revealed that when people sit next to each other and complete separate parts of a Simon task, response times are shorter when the participants’ stimulus appears in front of them than when the stimulus appears in the opposite side of space. According to the action co-representation account of this joint Simon effect (JSE), participants represent each other's responses and the compatibility effects emerge because of a set of facilitatory and inhibitory processes that are similar to those that are activated when individuals perform the entire Simon task alone. D. Guagnano, E. Rusconi, and C. A. Umiltà (2010) argued against this account as the sole mechanism based on their finding that a JSE was not observed when participants sat outside of each other's peripersonal space. Notably, the task in the Guagnano et al.'s was a modified version of the conventional JSE task designed to increase the independence of the partners. Here, we reconsider the arguments of Guagnano et al. and report a study in which the authors failed to replicate their key finding. Considering the extant JSE literature, we conclude that the null effect in Guagnano et al.'s study may be an anomaly and that co-representation remains a leading candidate for the critical process underlying JSEs.

Two studies were conducted to examine the relation between the gambler's fallacy (GF) and attentional processes associated with inhibition of return (IOR). In Study 1, participants completed rapid aiming movements to equally probable targets presented to the left and right. They also completed a gambling protocol in which they bet on the illumination of either target. Consistent with the IOR phenomenon, participants were slower to initiate their movements on trial N + 1 when the target was the same as trial N. Participants with more pronounced IOR were more likely to switch betting behavior after a win than participants with a smaller index. This betting behavior was also related to a GF index measured by a questionnaire. In Study 2, participants performed both the aiming task and the betting task with a partner. Each participant performed two trials before ceding to the partner. Thus we were able to examine IOR and betting behavior as a function of the participant's own previous trial and their partner's previous trial. The IOR effect was robust both within and between-participants. Participants were more likely to maintain their bet following an unsuccessful outcome regardless of whether it was their own outcome or their partner's outcome. This type of betting behavior is consistent with the GF. Individual IOR scores were a reliable predictor of betting behavior and the questionnaire was also successful in predicting behavior. In addition, the within-person IOR indices covaried with the GF index derived from the questionnaire. In summary, there appears to be a relation between IOR and the GF. We suggest that early humans developed specialized attentional systems to deal with non-random environmental contingencies, and that the automatic processes associated with these systems are sometimes maladaptive in artificial environments in which the same contingencies do not hold.

This paper, presented as the C. Lynn Vendien International Lecture given at the National Academy of Kinesiology, September 2011, provides context around the concept of accountability, the roles of the Academy, and knowledge translation as the basis for a framework for continued development of the National Academy of Kinesiology. The intent is to use the concepts presented in this paper as a catalyst for further discussion on opportunities for the Academy to serve the field of kinesiology as a knowledge broker and champion in addressing matters of important societal importance. Disability is used as an example of one such immediate opportunity.

In one foundational study of action-centred attention (Tipper et al. 1992), two patterns of distractor interference were reported: the ipsilateral effect - distractors on the same side of space as the effector caused more interference than distractors in the opposite side of space; and, the proximity effect - distractors closer to effector cause more interference than farther distractors. These patterns of interference are thought to emerge because distractors ipsilateral and closer to the effector activate salient competing responses and require more time to inhibit. One aspect that has not been addressed is how interference emerges when individuals need to choose responses between the hands. We hypothesized that distractors which activate responses for the other limb may cause greater interference than distractors that alter the movement specifications within a limb. This prediction is based on research showing that the specification of the arm occurs before the specification of movement direction and amplitude (Rosenbaum, 1980). Participants in the present study executed reaching movements to 1 of 4 (2 left, 2 right) possible target locations with and without a distractor. In Experiment 1, participants made ipsilateral reaches (left hand to left targets, right hand to right targets). In contrast to studies using one-handed reaches, a "contralateral effect" was observed in which distractors affording responses for the other hand caused more interference than distractors affording responses for the same hand. In Experiment 2 (a control study similar to Tipper et al., 1992), participants used their right hand to reach to all targets. Contrary to Experiment 1, a contralateral distractor interference effect was not observed. Together, the findings from the present research support the notion that attention is influenced by the actions being performed and, further, support Rosenbaum’s idea that the specification of the effector occurs earliest in motor planning. Meeting abstract presented at VSS 2012

The bimodal perception of speech sounds was examined in children with autism as compared to mental age—matched typically developing (TD) children. A computer task was employed wherein only the mouth region of the face was displayed and children reported what they heard or saw when presented with consonant-vowel sounds in unimodal auditory condition, unimodal visual condition, and a bimodal condition. Children with autism showed less visual influence and more auditory influence on their bimodal speech perception as compared to their TD peers, largely due to significantly worse performance in the unimodal visual condition (lip reading). Children with autism may not benefit to the same extent as TD children from visual cues such as lip reading that typically support the processing of speech sounds. The disadvantage in lip reading may be detrimental when auditory input is degraded, for example in school settings, whereby speakers are communicating in frequently noisy environments.

Children born very preterm, even with broadly normal IQ, commonly show selective difficulties in visuospatial processing and executive functioning. Very little, however, is known what alterations in cortical processing underlie these deficits. We recorded MEG while eight children born very preterm (≤32 weeks gestational age) and eight full-term controls performed a visual short-term memory task at mean age 7.5 years (range 6.4 – 8.4). Previously, we demonstrated increased long-range alpha and beta band phase synchronization between MEG sensors during STM retention in a group of 17 full-term children age 6-10 years. Here we present preliminary evidence that long-range phase synchronization in very preterm children, relative to controls, is reduced in the alpha-band but increased in the theta-band. In addition, we investigated cortical activation during STM retention employing synthetic aperture magnetometry (SAM) beamformer to localize changes in gamma-band power. Preliminary results indicate sequential activation of occipital, parietal and frontal cortex in control children, as well as reduced activation in very preterm children relative to controls. These preliminary results suggest that children born very preterm exhibit altered inter-regional functional connectivity and cortical activation during cognitive processing.

Results of a magnetoencephalography (MEG) brain imaging study conducted to examine the cortical responses during action execution and action observation in 10 healthy adults and 8 age-matched adults with Down syndrome are reported. During execution, the motor responses were strongly lateralized on the ipsilateral rather than the contralateral side in the Down syndrome group. Observation of movement activated a network of cortical regions that was similar to the control group; however, there was no significant peak activity in the motor areas. In addition, the overall pattern of neural activation was more scattered and less organized in the Down syndrome group. These results further support the hypothesis of a dysfunction in the execution/observation matching system in adults with Down syndrome.

Local alpha-band synchronization has been associated with both cortical idling and active inhibition. Recent evidence, however, suggests that long-range alpha synchronization increases functional coupling between cortical regions. We demonstrate increased long-range alpha and beta band phase synchronization during short-term memory retention in children 6–10 years of age. Furthermore, whereas alpha-band synchronization between posterior cortex and other regions is increased during retention, local alpha-band synchronization over posterior cortex is reduced. This constitutes a functional dissociation for alpha synchronization across local and long-range cortical scales. We interpret long-range synchronization as reflecting functional integration within a network of frontal and visual cortical regions. Local desynchronization of alpha rhythms over posterior cortex, conversely, likely arises because of increased engagement of visual cortex during retention.

In a series of previous experiments, we have shown that the completion of social tasks may involve the representation of the actions of our partners. Motivated by the recent proposal that such action co-representation may only occur when a partner is in peri-personal space, participants in our present study performed a JSE task in three separate conditions: (1) Close: seated .2m apart with stimuli appearing on a 17 screen; (2) Far: seated 1.5m apart with stimuli appearing on a 17 screen; and, (3) Far-Projector: seated 1.5m apart with the stimuli appearing on a 1.5x2.5m white board. Of additional interest to us was the fact that examining the role of peri-personal space necessitated the introduction of separate response spaces. Thus, in a departure from our previous work, participants executed their responses on separate keyboards. The observed JSEs in the Far and Far-Projector conditions were consistent with our previous work. However, we did not observe a JSE in what could be considered the baseline condition (Close condition). We attribute this latter outcome to be related to the introduction of separate work spaces. We contend that perceptual-motor interactions occur at multiple, interactive levels and that the spatial relations between the partners, the stimulus environment, and the response locations are all potential modulators of action co-representation. Acknowledgments: This research was funded by NSERC and an Early Researcher Award from the Ontario Ministry of Research and Innovation.

How humans understand the actions and intentions of others remains poorly understood. Here we report the results of a magnetoencephalography (MEG) experiment to determine the temporal dynamics and spatial distribution of brain regions activated during execution and observation of a reach to grasp motion using real world stimuli. We show that although both conditions activate similar brain areas, there are distinct differences in the timing, pattern and location of activation. Specifically, observation of motion revealed a right hemisphere dominance with activation involving a network of regions that include frontal, temporal and parietal areas. In addition, the latencies of activation showed a task specific pattern. During movement execution, the earliest activation was observed in the left premotor and somatosensory regions, followed closely by left primary motor and STG at the time of movement onset. During observation, there was a shift in the timing of activation with the earliest activity occurring in the right temporal region followed by activity in the left motor areas. Activity within these areas was also characterized by a shift to a lower frequency in comparison with action execution. These results add to the growing body of evidence indicating a complex interaction within a distributed network involving motor and nonmotor regions during observation of real actions.

It has been proposed that the deficits in social interaction seen in autism spectrum disorder (ASD) arise from problems in action perception stemming from a dysfunction of the mirror neuron system (MNS) — a neural network that becomes active during the performance and observation of action. A dysfunction of this system could have a cascading effect leading to deficits in social cognition because poor activation of the MNS during action observation may lead to an incomplete understanding of another person's actions, intentions and, ultimately, mental states. The present study tested the MNS dysfunction explanation by determining if people with ASD demonstrate a between-person inhibition of return (BP-IOR) effect. The BP-IOR effect, longer reaction times to targets presented at the location of another person's previous response relative to an unresponded-to location, has been hypothesized to be the result of the MNS co-representing the observed response and subsequently activating the mechanisms that cause IOR when individuals respond on their own (within-person IOR [WP-IOR]). Consistent with the MNS dysfunction hypothesis, participants with ASD did not demonstrate a BP-IOR effect in a condition in which they only observed the movement of the partner. The participants with ASD did demonstrate a WP-IOR effect suggesting that the mechanisms underlying IOR are intact in ASD. The contrast between the BP- and WP-IOR effects in the participants with ASD provides significant behavioural evidence for MNS dysfunction in ASD and has important implications for understanding this disorder.