More implicit and more explicit motor imagery tasks for exploring the mental representation of hands and feet in action.

The mental representation of the body in action can be explored using motor imagery (MI) tasks. MI tasks can be allocated along a continuum going from more implicit to more explicit tasks, where the discriminant is the degree of action monitoring required to solve the tasks (which is the awareness of using the mental representation of our own body to monitor our motor imagery). Tasks based on laterality judgments, such as the Hand Laterality Task (HLT) and the Foot Laterality Task (FLT), provide an example of more implicit tasks (i.e., less action monitoring is required). While, an example of a more explicit task is the Mental Motor Chronometry task (MMC) for hands and feet, where individuals are asked to perform or imagine performing movements with their limbs (i.e., more action monitoring is required). In our study, we directly compared hands and feet at all these tasks for the first time, as these body districts have different physical features as well as functions. Fifty-five participants were asked to complete an online version of the HLT and FLT (more implicit measure), and an online version of the MMC task for hands and feet (more explicit measure). The mental representation of hands and feet in action differed only when the degree of action monitoring decreased (HLT ≠ FLT); we observed the presence of biomechanical constraints only for hands. Differently, when the degree of action monitoring increased hands and feet did not show any difference (MMC hands = MMC feet). Our results show the presence of a difference in the mental representation of hands and feet in action that specifically depends on the degree of action monitoring.

Does physical weight alter the mental representation of the body? Evidence from motor imagery in obesity.

Obesity is a clinical condition that impacts severely the physical body. However, evidence related to the mental representation of the body in action is scarce. The few available studies only focus on avoiding obstacles, rather than participants imagining their own body. To advance knowledge in this field, we assessed the performance of 22 individuals with obesity compared with 30 individuals with a healthy weight in two tasks that implied different motor (more implicit vs. more explicit) imagery strategies. Two tasks were also administered to control for visual imagery skills, to rule out confounding factors. Moreover, we measured body uneasiness, through a standard questionnaire, as body image negativity could impact on other body representation components. Our findings do not show differences in the motor imagery tasks between individuals with obesity and individuals with healthy weight. On the other hand, some differences emerge in visual imagery skills. Crucially, individuals with obesity did report a higher level of body uneasiness. Despite a negative body image and visual imagery differences, obesity per se does not impact on the representation of the body in action. Importantly, this result is independent from the level of awareness required to access the mental representation of the body.

Self-perception in anorexia nervosa: When the body becomes an object.

OBJECTIVE: Women with anorexia nervosa (AN) act as if they have a larger body, as evidenced in obstacle avoidance tasks, where an allocentric perspective is adopted. This alteration emerges not only when they perform, but also when they imagine movements. However, no previous study has investigated own body centered tasks. As such, in this study we aim at documenting if women with AN show an altered behaviour also when the task requires a first-person perspective. METHOD: We explored the performance of eleven woman affected by AN compared to eighteen matched controls, in two motor imagery tasks based on a self-frame of reference, the Hand Laterality Task and the Mental Motor Chronometry Task. Moreover, two control tasks relative to visual imagery were administered. RESULTS: In the Hand Laterality Task, affected participants did not adopt a motor strategy to judge hands laterality (i.e. no biomechanical constraints effect). Crucially, they also showed an altered behavior in the control task. Similarly, they did not show the expected isochrony in the Mental Motor Chronometry Task, when actions pertained the left (but not the right) hand, in absence of any difference in the control task. CONCLUSIONS: Our findings reveal altered imagery processes in AN. Specifically, affected participants adopt a third-person, rather than a first-person perspective, even when the task requires to imagine their own body in an internal frame of reference. In other words, participants with AN objectify body stimuli. Different mechanisms (i.e., checking behaviour; mirror self-reflection; altered multisensory integration) can explain such an altered imagery in AN.

Talking with hands: body representation in British Sign Language users.

Body representation (BR) refers to the mental representation of motor, sensory, emotional and semantic information about the physical body. This cognitive representation is used in our everyday life, continuously, even though most of the time we do not appreciate it consciously. In some cases, BR is vital to be able to communicate. A crucial feature of signed languages (SLs), for instance, is that body parts such as hands are used to communicate. Nevertheless, little is known about BR in SL: is the communicative function of the body overwriting the physical constraints? Here, we explored this question by comparing twelve British Sign Language (BSL) learners to seventeen tango dancers (body expertise but not for communication) and fourteen control subjects (no special body expertise). We administered the Body Esteem Scale (BES), the Hand Laterality Task (HLT) and the Mental Motor Chronometry (MMC). To control for visual imagery, we administered ad hoc control tasks. We did not identify parameters able to differentiate between SL users and the other groups, whereas the more implicit parameters distinguished clearly tango dancers from controls. Importantly, neither tasks on visual imagery nor the BES revealed differences. Our findings offer initial evidence that linguistic use of the body not necessarily influences the cognitive components we explored of body representation.

Mental representation of the body in action in Parkinson's disease.

Mixed findings characterize studies in Parkinson's disease (PD): some studies indicate a relationship between physical impairments and the ability to mentally represent the body, while others suggest spared abilities for this cognitive function. To clarify the matter, in the present study we explored the mental representations of the body in action in the same PD patients, taking also into account lateralization of symptoms and visual imagery skills. 10 PD patients with left- (lPD), 10 with right (rPD) lateralized symptoms (lPD), and 20 matched healthy controls have been recruited for the study. All patients were screened for neuropsychological impairments. To explore a more implicit component we used the hand laterality task (HLT), while the mental motor chronometry (MMC) was used to explore a more explicit one. Two control tasks, with objects instead of body parts, were administered to control for visual imagery skills. In the HLT, we detected the effects of biomechanical constraints effects in both controls and PD patients. In the latter group, importantly, this was true independently from lateralization of symptoms. In the MMC, we found the expected positive correlation between executed and imagined movements for both hands in controls only, while all PD patients, again independently form lateralization, only showed this effect for the left hand. In terms of visual imagery, only rPD patients differed from controls when asked to implicitly rotate letters, and in terms of accuracy only. However, this difference is explained by executive functions measured through the neuropsychological assessment rather than by a "pure" visual imagery impairment. In summary, our findings suggest that two different aspects of the mental representations of the body in action, one more implicit and the other more explicit, can be differently affected by PD. These impairments are unlikely explained by a basic visual imagery deficit. When present, impairments concern a higher dimension, related to motor functions and awareness, and not driven by sensory impairments, as shown by the independence of effects from physical laterality of symptoms.

In search of the disappeared half of it: 35 years of studies on representational neglect.

OBJECTIVE: Representational neglect (RN) is a neuropsychological deficit mostly occurring after right brain damage affecting the mental imagery domain. Patients suffering from RN are unable to represent, describe, or explore the contralesional side of their mental images. Since its first description in 1978, RN has been explored using different theoretical frameworks and experimental paradigms. After 35 years, the nature of its behavioral and anatomical correlates is still unclear. METHOD: We reviewed studies on RN published from 1978-2013 to systematize available knowledge and to shed light on future research directions. RESULTS: The huge variety of tests used to diagnose RN reflects the different clinical features of the deficit, which can compromise space sectors and memory storage, depending on the stimulus to be imagined, even in a dissociated fashion. RN has been frequently described after parietal, temporal, and frontal right brain lesions, even though reliable group studies are scanty. CONCLUSION: A number of priorities concerning RN were identified. Future studies might take into account several aspects of RN that are still poorly explored, starting from a more systematized investigation of RN using larger group studies. RESULTS might add pieces to the puzzle of spatial cognition and its neural basis in mental imagery, paving the way for tailored motor and cognitive rehabilitation programs.

Motor imagery in spinal cord injury patients: moving makes the difference.

Both real action control and execution and motor imagery abilities require knowledge of the spatial location of body parts, in other words efference copy information and feedbacks from the sensory system (Frith et al., 2000, Philos. Trans. R. Soc. Lond. B. Biol. Sci., 355, 1771). Spinal cord injuries induce severe motor disability, due to a damage of the descending motor pathways (Cramer et al., 2007, Exp. Brain. Res., 177, 233). Patients' motor imagery competences are variably reported as either normal or defective (Decety & Boisson, 1990, Eur. Arch. Psychiatry Clin. Neurosci., 240, 39; Lacourse et al., 1999, Behav. Brain Sci., 104, 73). We explored biomechanical constraint effects in Spinal Cord Injury (SCI) patients, as they are considered the most reliable indexes of motor imagery abilities (Parsons, 1987b, Cogn. Psychol., 19, 178). Sixteen spinal cord injuries patients and 16 neurologically unimpaired subjects have been administered with (1) the Hand Laterality Task (HLT), in which subjects were asked to judge the laterality of a rotated hand; and (2) the Mirror Letter Discrimination Task (MLD), in which subjects were asked to judge if a rotated character was in its correct upright position or mirror-reversed form. Our patients did not present the effect of stimulus orientation, neither did they show any effect related to biomechanical constraints. Based on these data, the hypothesis is that SCI patients' performance may be ascribed to the use of a different strategy to solve the tasks, based on memory rather than on mental rotation.