The body schema and multisensory representation(s) of peripersonal space

To guide the movement of the body through space, the brain must constantly monitor the position and movement of the body in relation to nearby objects. The effective piloting of the body to avoid or manipulate objects in pursuit of behavioural goals requires an integrated neural representation of the body (the body schema) and of the space around the body (peripersonal space). In the review that follows, we describe and evaluate recent results from neurophysiology, neuropsychology, and psychophysics in both human and non-human primates that support the existence of an integrated representation of visual, somatosensory, and auditory peripersonal space. Such a representation involves primarily visual, somatosensory, and proprioceptive modalities, operates in body-part-centred reference frames, and demonstrates significant plasticity. Recent research shows that the use of tools, the viewing of ones body or body parts in mirrors, and in video monitors, may also modulate the visuotactile representation of peripersonal space.

Visuo-tactile congruency influences the body schema during full body ownership illusion

Previous research showed that full body ownership illusions in virtual reality (VR) can be robustly induced by providing congruent visual stimulation, and that congruent tactile experiences provide a dispensable extension to an already established phenomenon. Here we show that visuo-tactile congruency indeed does not add to already high measures for body ownership on explicit measures, but does modulate movement behavior when walking in the laboratory. Specifically, participants who took ownership over a more corpulent virtual body with intact visuo-tactile congruency increased safety distances towards the laboratory’s walls compared to participants who experienced the same illusion with deteriorated visuo-tactile congruency. This effect is in line with the body schema more readily adapting to a more corpulent body after receiving congruent tactile information. We conclude that the action-oriented, unconscious body schema relies more heavily on tactile information compared to more explicit aspects of body ownership.     

Beyond differences between the body schema and the body image: insights from body hallucinations

The distinction between the body schema and the body image has become the stock in trade of much recent work in cognitive neuroscience and philosophy. Yet little is known about the interactions between these two types of body representations. We need to account not only for their dissociations in rare cases, but also for their convergence most of the time. Indeed in our everyday life the body we perceive does not conflict with the body we act with. Are the body image and the body schema then somehow reshaping each other or are they relatively independent and do they only happen to be congruent? On the basis of the study of bodily hallucinations, we consider which model can best account for the body schema/body image interactions.     

Multiple timescales of body schema reorganization due to plastic surgery

Plastic surgery modifies the distribution of mass centers of a person’s body segments, changing his or her posture. The functional reorganization processes that lead subjects to re-integrate these body changes into a new stable body (posture) schema is poorly understood but current theories suggest the possible contribution of two components: a feedback mechanism that strongly depends on sensory input and an internal model that is relatively less dependent on sensory input and improves posture control, for example by compensating for delayed feedback. To assess the relative contributions of these two mechanisms during the functional reorganization of a posture scheme, we have conducted a longitudinal postural study in a population of healthy adults who were subject to breast plastic surgery to reduce or augment body weight. We measured participants’ orthostatic posture and ground reaction force immediately after, after 4 months, and 1 year after the surgery. To investigate the role of visual sensory information in the reorganization process we tested the participants with eyes open and closed. Our results indicate that participants find a new dynamical equilibrium within a few days. However, posture maintenance remains sub-optimal long after the center of masses and the resultant of ground reaction force stop changing; in some cases, for more than 4 months. Furthermore, the re-adaptation process is faster and more efficient in the eyes-open than in the eyes-closed condition. These results suggest that the reorganization involves different subsystems (responsible for the biomechanical changes, the re-calibration of feedback mechanisms, and the re-adaptation of internal models), which act at different timescales.     

The man who executed "imagined" movements: evidence for dissociable components of the body schema

We examined the nature of representations underlying motor imagery and execution in a patient (CW) with bilateral parietal lesions. When imagining hand movements, CW executed the imagined motor act but was unaware of the movements. These movements were significantly more accurate than volitional movements for the left but not right hand. CW also exhibited preserved motor imagery for the left but not right hand. Consistent with previous accounts, these findings suggest that motor imagery may normally involve the inhibition of movements. CW's unawareness of movements during motor imagery may reflect inattention or misattribution of the unexpected sensory feedback. Furthermore, in line with current models of motor control, motor imagery may depend on the integrity of a "forward model" derived from motor outflow information to generate a prediction of the consequences of a motor command. Such predictions appear to be preserved for imagery of left but not right hand movements in CW. Action may additionally depend on precise updating of effector position derived from the comparison of predicted and actual sensory information. We propose that CW's impaired volitional movements may be attributable to the degradation of such an updating mechanism.     

A schema for common cents

Drawings from memory of a penny, nickel, dime, and quarter were obtained from 125 undergraduates. The modal recalls for the heads of all four coins were identical, suggesting that a schema for coins exists. In an attempt to have the schema produced directly, another 75 students designed either a 2-, 7-, or 20-cent piece that would fit into our present currency. The modal drawing for this task was identical to the modal recalls. The schema for the heads derived from these experiments differs from existing coins and is not an average of them.     

The role of the dynamic body schema in praxis: evidence from primary progressive apraxia

On an influential model of limb praxis, ideomotor apraxia results from damage to stored gesture representations or disconnection of representations from sensory input or motor output (Heilman & Gonzalez Rothi, 1993; Gonzalez Rothi et al., 1991). We report data from a patient with progressive ideomotor limb apraxia which cannot be readily accommodated by this model. The patient, BG, is profoundly impaired in gesturing to command, to sight of object, and to imitation, but gestures nearly normally with tool in hand and recognizes gestures relatively well. In addition, performance is profoundly impaired on imitation of meaningless gestures and on tasks requiring spatiomotor transformations of body-position information. We provide evidence that BG's apraxia is largely attributable to impairments external to the stored gesture system in procedures coding the dynamic positions of the body parts of self and others; that is, the body schema. We propose a model of a dynamic, interactive praxis system subserved by posterior parietal cortex in which stored representational elements, when present, provide "top-down" support to spatiomotor procedures computed on-line. In addition to accounting for BG's performance, this model accommodates a common pattern of ideomotor apraxia more readily than competing accounts.     

Psychic tonus, body schema and the parietal lobes: a multiple lesion case analysis

The psychic tonus model (Braun and colleagues, 1999, 2002, 2003, 2006) states that the left hemisphere is a "booster" of internal experience and behavior in general, and that the right hemisphere is a "dampener". Twenty-five patients with a "positive" extreme disturbance of body schema (somatoparaphrenia) and 37 patients with a "negative" disturbance of body schema (autotopagnosia or Gerstmann's syndrome), all following a unilateral parietal lesion, were found in the literature and were analyzed to test predictions from Braun's "psychic tonus" model. As expected, patients with a positive syndrome had a right hemisphere lesion significantly more frequently, and those with a negative syndrome had a left hemisphere lesion significantly more frequently. Thus the psychic tonus model of hemispheric specialization, previously supported with regard to psychomotor baseline, libido, talkativeness, memory, auditory and visual perceptual tonus, now incorporates the tonus of representation of the body (body schema) in the parietal lobes.     

Rule-based schema matching for ontology-based mediators

Mediating heterogeneous data sources heavily relies on explicit domain knowledge expressed, for example, as ontologies and mapping rules. We discuss the use of logic representations for mapping schema elements onto concepts expressed in a simplified ontology for cultural assets. Starting with a logic representation of the ontology, criteria for a rule-based schema matching are exemplified. Special requirements are the handling of uncertain information and the processing of hierarchical XML structures representing instances.     

Fragment and schema models for recall

Two general conceptualizations of recall may be distinguished. One holds that recall is sub-served by memory traces in which representations of different aspects of external events are linked directly to each other. The other holds that these representations are connected via a mediating concept. Formalizations of these views are provided by two theories examined by Ross and Bower (1981a): the “fragment” and “schema” models, respectively. Ross and Bower found that patterns of cued recall of clusters of words with a common theme were predicted well by the schema model, but not by the fragment model. Two experiments reported here show that the reverse is true if the clusters of words are selected randomly. Ross and Bower also considered separately a third theory, the “horizontal” model. However, the horizontal model is shown here to be a constrained form of the fragment model. Another constrained form of the fragment model, termed the “link” model, is introduced and is shown to provide an account of encoding as well as of retrieval that, although it is outstandingly parsimonious, is also approximately accurate. Finally, it is shown that the memory structures characterized by the fragment model may be interpreted as either graphs or digraphs: that is, networks with either bidirectional or unidirectional connections between nodes.     

A schema of deduction theorems for the propositional calculus

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A schema of deduction theorems for the propositional calculus

     

Making the body (w)hole: A semiotic exploration of body modifications

Abstract

Cultural norms of attraction are dynamic and fluid, and are psychologically intertwined with acts of corporeal modification that use the body as signifier. These norms are expressed in various ways by individuals, but can be seen most plainly when they are worn on the body, such as with body piercing and tattooing. An intertextual understanding of how body modifications play a role in the integration of psyche and soma appears to motivate understanding of how individual choices are reflections of cultural mores. Psychodynamic and semiotic processes from case examples are provided to illustrate how individuals may move between affect and expressiveness as well as how reading the body as text can generate new understandings of an individual's decision to modify, thus allowing clinicians to better work with their modified clients.     

Further tests of Schmidt's schema theory: development of a schema rule for a coincident timing task

The present study investigated the generalizability of Schmidt's (1975) schema theory to an open-skill (Poulton, 1957) situation. Subjects attempted to time a preferred-hand button press so that it was coincident with the lighting of the last of a series of run way lights whose apparent velocity was 4023 mm/sec. Prior to five trials of performance on the criterion task, subjects received 40 trials in which they either (a) watched (low response requirements) or (b) responded with the nonpreferred hand (high response requirements) to a stimulus moving at (a) a constant (2235, 3129, 4917, or 5812 mm/sec) velocity (low stimulus variability) or (b) different velocities (high stimulus variability) from trial to trial. Subjects receiving high stimulus variability and high response requirements during training had significantly lower absolute error on the criterion task than did those in the other conditions. The results were discussed in terms of the type of practice which facilitates development of a schema rule for coincident-timing situations.     

A qualitative review of perception of change for male perpetrators of domestic abuse following abuser schema therapy (AST)

Introduction: Domestic abuse is known to have detrimental effects on all members of the family, yet it is often difficult for victims to leave. It is therefore important to research available intervention programmes for perpetrators who want to change their behaviour. Intervention programmes for perpetrators are informed by different theoretical and philosophical approaches, such as pro‐feminism, psychopathology or biopsychosocial theories. However, there is little consensus to the most effective intervention and there is a paucity of qualitative research on the perspectives of the perpetrators who attend the available therapies. Aim: The aim of this research was to discover the perceptions of change of 18 male, heterosexual perpetrators with female partners who self referred to a community‐based therapy service providing abuser schema therapy (AST). Method: A qualitative methodology was adopted using semi‐structured interviews on completion of therapy, and at three, six, nine and 12 months follow‐up. A content analysis was conducted and data was coded and mapped against a priori variables. Findings: The findings indicated that the four highest rated variables were: (1) a reduction of anger, (2) an increase in communication and assertiveness skills, (3) an increase in ability to think prior to behaviour, and (4) responsibility for personal power. The findings are discussed in relation to the perceived changes for perpetrators. Conclusions: In conclusion, this study seeks to contribute to the development of future effective interventions to reduce aggression within the home.     

Tools for Change

Abstract

This paper discusses the ways in which one may incorporate political action into a client's therapy process so the client may incorporate it into her/his life. A framework for defining this as ethical, therapeutic and necessary to the client is presented. A number of suggestions for helping clients and therapists to become more politically active, as well as vignettes demonstrating how this might work with clients in the therapy process are provided.