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Previous studies showed that imitation of finger and hand/arm gestures could be differentially impaired after brain damage. However, so far, the interaction between gesture meaning and body part in imitation deficits has not been fully assessed. In the present study, we aimed at filling this gap by testing 36 unilateral left brain-damaged patients with and without apraxia (20 apraxics), and 29 healthy controls on an imitation task of either finger or hand/arm meaningful (MF) gestures and meaningless (ML) movements, using a large sample of stimuli and controlling for the composition of the experimental list. Left-brain damaged patients imitated ML finger worse than hand/arm movements, whereas they did not show the same difference in MF gesture imitation. In addition, apraxic patients imitated finger movements worse than hand/arm movements. Furthermore, apraxic patients' imitation performance was equally affected irrespective of the action meaning, whereas non-apraxic patients showed better imitation performance on MF gestures. Results suggest that MF gestures are processed as a whole, as imitation of these gestures relies on the stored motor programs in long-term memory, independently of the body part involved. In contrast, ML movements seem to be processed through direct visuo-motor transformations, with left-brain damage specifically disrupting imitation performance of the more cognitive demanding finger movements., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Adaptive interactions with the environment require optimal integration and segregation of sensory information. Yet, temporal misalignments in the presentation of visual and auditory stimuli may generate illusory phenomena such as the sound-induced flash illusion, in which a single flash paired with multiple auditory stimuli induces the perception of multiple illusory flashes. This phenomenon has been shown to be robust and resistant to feedback training. According to a Bayesian account, this is due to a statistically optimal combination of the signals operated by the nervous system. From this perspective, individual susceptibility to the illusion might be moulded through prolonged experience. For example, repeated exposure to the illusion and prolonged training sessions partially impact on the reported illusion. Therefore, extensive and immersive audio-visual experience, such as first-person shooter videogames, should sharpen individual capacity to correctly integrate multisensory information over time, leading to more veridical perception. We tested this hypothesis by comparing the temporal profile of the sound-induced illusion in a group of expert first-person shooter gamers and a non-players group. In line with the hypotheses, gamers experience significantly narrower windows of illusion (~87 ms) relative to non-players (~105 ms), leading to higher veridical reports in gamers (~68%) relative to non-players (~59%). Moreover, according to recent literature, we tested whether audio-visual intensive training in gamers could be related to the incidence of migraine, and found that its severity may be directly proportioned to the time spent on videogames. Overall, these results suggest that continued training within audio-visual environments such as first-person shooter videogames improves temporal discrimination and sensory integration. This finding may pave the way for future therapeutic strategies based on self-administered multisensory training. On the other hand, the impact of intensive training on visual-related stress disorders, such as migraine incidence, should be taken into account as a risk factor during therapeutic planning., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

One single bout of exercise can be associated with positive effects on cognition, due to physiological changes associated with muscular activity, increased arousal, and training of cognitive skills during exercise. While the positive effects of life-long physical activity on cognitive ageing are well demonstrated, it is not well established whether one bout of exercise is sufficient to register such benefits in older adults. The aim of this study was to test the effect of one bout of exercise on two cognitive processes essential to daily life and known to decline with ageing: audio-visual perception and immediate memory. Fifty-eight older adults took part in a quasi-experimental design study and were divided into three groups based on their habitual activity (open skill exercise (mean age = 69.65, SD = 5.64), closed skill exercise, N = 18, 94% female; sedentary activity-control group, N = 21, 62% female). They were then tested before and after their activity (duration between 60 and 80 minutes). Results showed improvement in sensitivity in audio-visual perception in the open skill group and improvements in one of the measures of immediate memory in both exercise groups, after controlling for baseline differences including global cognition and health. These findings indicate that immediate benefits for cross-modal perception and memory can be obtained after open skill exercise. However, improvements after closed skill exercise may be limited to memory benefits. Perceptual benefits are likely to be associated with arousal, while memory benefits may be due to the training effects provided by task requirements during exercise. The respective role of qualitative and quantitative differences between these activities in terms of immediate cognitive benefits should be further investigated. Importantly, the present results present the first evidence for a modulation of cross-modal perception by exercise, providing a plausible avenue for rehabilitation of cross-modal perception deficits, which are emerging as a significant contributor to functional decline in ageing.

We propose STIMA, a short test for ideo-motor apraxia, allowing us to quantify the apraxic deficit according to action meaning and affected body segment. STIMA is based on a neurocognitive model holding that there are two processes involved in action imitation (i.e., a semantic route for recognizing and imitating known gestures, and a direct route for reproducing new gestures). The test allows to identify which imitative process has been selectively impaired by brain damage (direct vs. semantic route) and possible deficits depending on the body segment involved (hand/limb vs. hand/fingers). N = 111 healthy participants were administered with an imitation task in two separated blocks of known and new gestures. In each block, half of the gestures were performed mainly with the proximal part of the upper limb and the remaining half with the distal one. It resulted in 18 known gestures (nine proximal and nine distal) and 18 new gestures (nine proximal and nine distal) for a total of 36. Each gesture was presented up to a maximum of two times. Detailed criteria are used to assign the final imitation score. Cut offs, equivalent scores and main percentile scores were computed for each subscale. Participants imitated better known than new gestures, and proximal better than distal gestures. Age influenced performance on all subscales, while education only affected one subscale. STIMA is easy and quick to administer, and compared to previous tests, it offers important information for planning adequate rehabilitation programs based on the functional locus of the deficit.

Neuropsychological and neuroimaging studies suggest distinct body representations involved in coding one's and others' body. Other influential theories, however, instead posit a unique model behind coding multisensory information about one's own body and visual information about others. An efficient way to further investigate this issue can be through testing individuals with anomalous anatomical and sensorimotor bodily features. In these people, the representation of their own body is held to be different with respect to the average population due to the peculiar properties of their body, and any experimental finding supposedly mediated by this representation should reflect such difference. We reviewed the most relevant studies reporting individuals with anomalous anatomical and sensorimotor bodily features engaged in (a) handedness task, (b) visual processing of biological motion and (c) visual processing of body shape. The performance in all three kinds of cognitive processes is affected by anomalous body features of the tested populations. However, the reviewed data are also in favor of a body model extrapolated by visual experience of others which mediates processing of biological stimuli and which operates in parallel, or as an alternative, to the representation of one's own body. In light of these results, pure visual and pure embodied accounts behind visual processing of biological stimuli should be reconsidered., (2009 Elsevier Ltd. All rights reserved.)

Recent evidence using a modified Simon task suggests that hand processing involves implicit coding of the spatial position of the hand relative to the side of the body to which it is attached from the viewer's reference point. This effect, called the Sidedness effect, has been found to emerge only when at least the forearm is present (the forearm thus providing the spatial reference for representing the rest of body) and it has been interpreted within the framework of the structural representation of the body. In this study we use the same modified Simon task to investigate whether hand processing involves the implicit access to a spatially and bio-mechanically organized structural body representation. In a first experiment the hand stimuli were attached to a body inappropriately without respecting the bio-mechanical constraints and no Sidedness effect was found. In Experiment 2 where the hand stimuli were presented attached to a non-bodily shape the Sidedness effect was observed only when they were attached appropriately. Whilst previous research has involved explicit representational processes, our results suggest that we can implicit access to a 'structural description of the body' and elaborate the anatomical and bio-mechanical plausibility., (2009 Elsevier Ltd. All rights reserved.)

In this study we investigated with a priming paradigm whether uni and bimanual actions presented as primes differently affected language processing. Animals' (self-moving entities) and plants' (not self-moving entities) names were used as targets. As prime we used grasping hands, presented both as static images and videos. The results showed an interference effect with unimanual action primes (both static and moving) with plants' names. No modulation of responses for animals' names was found. We argue that in the present task plants elicit information on unimanual grasping actions they support, while the lack of effect for animals could be due to them being better characterized as active agents.

The authors used a modified Simon task (J. R. Simon, 1969) to assess the automatic recognition of handedness. Participants responded to the color of a circle in the center of the photograph of a right or a left hand, displayed in the center of the computer screen. A regular Simon effect was found for back views, whereas a reverse Simon effect was found for palm views. This pattern of results was found when the forearm was present (Experiment 2), when 1 finger at a time was rendered invisible (Experiment 3), and when the hands were connected to a body image (Experiment 4). When the hands were cut at the wrist, no effect emerged (Experiment 1). These findings suggest an automatic encoding of the relative position of the hand in relation to the body (imaginary or real) rather than the automatic encoding of handedness.

The aim of this study was to bring to the surface the strategic use of imitative processes in the context of a 2-route model: (a) direct imitation, used in reproducing new, meaningless actions, and (b) imitation based on stored semantic knowledge of familiar meaningful actions. Three experiments were carried out with healthy participants who reproduced meaningful and meaningless actions within an established time limit. The study investigated 3 factors that could potentially affect the selection of processes used for imitation: (a) the composition of the experimental list (blocked or mixed presentation), (b) the presence-absence of instructions (Experiments 1 and 2), and (c) the relative proportions of the stimuli (Experiment 3). Overall, the results suggest that each of these factors influences the selection of imitative strategies in healthy individuals with temporarily reduced capacities, as happens in the case of brain-damaged patients., (Copyright 2004 APA.)

In this study, we tested whether in certain experimental conditions the distal and proximal motor components may dissociate in action imitation, and how the distal component and the object representation may interact. Experiments 1-3 were carried out using a dual task procedure in which an action span and a motor suppression were coupled. In Experiment 1, it was shown that action spans were affected more by a distal movement (e.g. distal motor suppression) than by a proximal movement (proximal motor suppression). In Experiment 2, it was demonstrated that the reduction of the action spans was not due to the distal motor suppression being more difficult than the proximal motor suppression. In Experiment 3, pantomimes were replaced with the corresponding objects and the participants were asked to mime the objects, reproducing the appropriate actions. During the presentation of the objects, the participants were engaged in a motor suppression that was performed either by the hand or by the arm. The distal motor suppression reduced the pantomime span more significantly than the proximal motor suppression. Experiment 4 showed that the spans of pantomimes of objects shown in Experiment 3 are longer when participants do not perform motor suppressions. Our results suggest that in normal subjects a difference between the distal and the proximal motor component can be observed under dual task conditions and that distal motor suppression seems to interfere both with the encoding of action and with pragmatic representation of objects.