Motor Imagery in Clinical Disorders: Importance and Implications

One of our most remarkable mental capacities is the ability to use our imagination voluntarily to mimic or simulate sensations, actions, and other experiences. For example, we can “see” things in our mind’s eye,“hear”sounds in our mind’s ear, and imagine motor experiences like running away from, or perhaps “freezing” in the face of, danger. Since the early 1900s (1), researchers have investigated “mental imagery” or the multimodal cognitive simulation process by which we represent perceptual information in our minds in the absence of sensory input (2). Although visual imagery has attracted most research attention to date (3), there has been an upsurge of interest in cognitive neuroscience and sport psychology in non-visual simulation processes such as “motor imagery” (MI) or the mental rehearsal of actions without engaging in the physical movements involved (4). This trend is attributable mainly to the discovery of close parallels between the neurocognitive mechanisms underlying imagination and motor control. Specifically, inspired by Jeannerod’s (5–7) simulation theory of action representation, researchers have discovered that MI recruits similar neural pathways and mechanisms to those involved in actual movements. For example, Hétu et al. (8) showed that the neural network of MI includes several cortical regions known to underlie actual motor execution. Building on this apparent functional equivalence between imagined and executed actions, the present article explores the implications of research on MI for increased understanding of three clinical conditions – post-traumatic stress disorder (PTSD), personality disorder, and social anxiety disorder (SAD). Before we begin, however, some background information on imagery processes in psychopathology is required. Arising from Kosslyn’s proposition that mental imagery plays “a special role in representing emotionally charged material” [(9), p. 405; see also Ref. (10)], researchers have examined the role of imagery processes in the onset, maintenance, and treatment of various psychological disorders (11–13). A consistent finding is that negative, vivid, and distressing involuntary (“intrusive”) imagery is a “transdiagnostic” feature of depression (14), SAD (15), PTSD (16), and obsessivecompulsive disorder [OCD; (17)]. For example, Weßlau and Steil (14) reported that more than one in three depressed people suffer from involuntary negative mental imagery. Furthermore, people’s capacity to use imagery prospectively is significantly impaired in certain clinical disorders. Thus, Morina et al. (18) discovered that depressed patients were less capable of imagining positive future outcomes than were nondepressed controls. Imagery processes also help in the treatment of psychopathology. Indeed, Holmes et al. (19) evaluated the therapeutic value of “imagery rescripting” [where distressing images are modified to change their associated thoughts, feelings, and behavior; (20)] in the treatment of PTSD. Clearly, imagery research represents “a new and important arena” [Pearson et al. (13), p. 3] for clinical psychology. Despite increased awareness of imagery processes in psychopathology, there is at least one significant gap in research in this field. Specifically, little is known about the role of MI in clinical disorders. Curiously, despite the multimodal nature of imagery (21), clinical researchers have tended to focus mainly on its visual component. Thus, Weßlau and Steil (14) proclaimed that in imagery, although “other sensory components such as smells, sounds, or haptic sensations . . . may be present . . . the visual aspect is the necessary and sufficient condition” (our italics, p. 274). This proposition may be challenged, however, by evidence that mildly to moderately depressed patients experience proportionately more somatic (39.6%) than visual (27.2%) imagery (17). More importantly, MI processes may help to elucidate the mechanisms underlying clinical conditions with distinctive motor components. For example, Chen et al. (22) discovered that depressed patients have difficulties in the mental rotation of hand stimuli. These imagery deficits reflect “an underlying slowing down of motor preparation, which may contribute to psychomotor retardation” (p. 341). Let us now consider three specific disorders in which MI processes are potentially significant PTSD, personality disorders, and SAD.