Motor Imagery, Mental Health, and the Brain

jrlewis's picture

Julia Lewis

11/7/08

Project Draft

Motor Imagery, Mental Health, and the Brain

I look the through my horse’s ears and imagine entering the ring, picking up a slow collected canter, and approaching the first fence. After we leave the ground, I focus straight ahead, finding the path that will yield a nice round turn to the fence 150O to our left. I sit back, balance my horse, and our perfect spot to take off comes closer with each stride. When we land, I shift my weight out to increase the arc of our path to the next fence. I apply a lot of outside leg to steady my horse as the next jump comes into sight…

“Shouldn’t you go help her prepare?” asks one of my trainer’s other clients. “Nope, she needs to do her own thing now,” my trainer replies.

My own thing is a kind of visualization known as motor imagery. “Motor Imagery … is defined as the mental simulation of a specific action without any corresponding motor output.” (1) In this technique, I imagine riding the course that I must perform for the competition. This includes considering information about my position and trajectory in the ring.

Motor imagery is a process in which a person mentally rehearses motor actions as they occur with respect representational planes. It is a form of internal imagery because the person is picturing themselves and their own movements. For example, I visualize my position when asking my horse for a flying lead change, not her response. The horse would be considered an external figure here.

One theory on the efficacy of motor imagery as a training tool is the neuromuscular theory. “A specific part of the brain, the supplementary motor area, is involved in both imagined and executed motor actions.” (2) Therefore, the desired motor action can be practiced in the absence of physical activity.

In order to achieve a deeper understanding of mental imagery, it is relevant to consider how the images in the mind are made. In his essay, “Getting it Less Wrong, the Brain’s Way: Science, Pragmatism, and Multiplism,” Grobstein describes the origin of the picture in the brain. The human brain is a bipartite system, with a “painter” and an “audience” who views it. In the act of perception, the painter interprets a number of inputs and the result is a picture. “This characteristic … make[s] the metaphor of the “painter” and the audience an appealing one: [painter] brain processes not only create the picture without themselves being visible to the audience,” (3).

One example of such phenomenon is the perception of ambiguous figures. Ambiguous figures are images that can be interpreted in two equally acceptable ways. However, there is only one picture presented in the head. The painter gives priority to different sensory observations in order to construct a single image. The audience is unaware of the existence of multiple interpretations. The audience may become aware of alternative interpretations when the perceiving the image a second time or at the suggestion of another person. The image in the mind is not an objective representation of reality. It is simply a prioritized summary of inputs made by the painter for the audience to view.

Jeannerod introduces a distinction between mental images that are generated by the unconscious alone or the unconscious and conscious in combination. The painter is loosely analogous to the more commonly used term unconscious and the audience to the conscious. He also describes mental imagery in the context of a two-part bran, the conscious and unconscious. Motor preparation is an unconscious process that the conscious does not have access to until the specific action occurs. During motor imagery, the conscious has access and ability to alter the picture being painted in the mind.

These two mental processes are related; he argues that they exist along a continuum of conscious involvement. Therefore, it is less useful to discuss the difference between automatic and conscious actions. (4) He hypothesizes that time is a determining factor. Mental preparations are short-lived processes, as the length of time they persist increases, the chance of conscious access increases.

An alternative route of conscious awareness, is the event of an unexecuted action. “The content of the motor representation [could] not reach consciousness because it [was] cancelled as soon as the corresponding movement [was] executed,” (1). Interestingly, amputated patients describe awareness of potential movement by their phantom limbs. (1) Therefore, it is possible to transition from motor preparation to motor imagery. This idea is consistent with the observed functional equivalence of motor preparation and motor imagery. (1)

When human brains perceive events, they generate motor imagery and preparations prior to taking action. This representation includes considerations such as aims, means, and outcome. The simulation theory states that mental representations of the future are identical to actions that do not get executed. There is a similarity in mental states between action simulation and execution. (5)

This process is occurs in a variety of contexts, however it is interesting to note its influence on interpersonal relationships. Observation of another’s actions leads a person to attempt to comprehend and predicts the other’s behavior. This practice is termed mind-reading. (6) In the process of mind-reading, the mechanisms activated in the observer’s mind are the same as those activated when imagining or preparing the act. (5) Therefore, motor representation is a significant part of interpersonal relationships.

An improper motor representation, leads to incorrect mind-reading, and problematic interpersonal relationships. During interaction between two individuals, each person must make motor representations about their own intentions and those of their partner. In healthy individuals, the brain processes for these two tasks are separated. However, it is possible for the two mental representations to overlap resulting in confusion about the origin of actions and intentions. This is a possible explanation for types of psychotic behavior in the mentally ill.

A relevant phenomenon is the experience of motor passivity by schizophrenics. Motor passivity is a symptom in which, the patient describes an external agent controlling their motor actions. Schizophrenics are unable to differentiate between the actions and intentions of themselves and others. Specifically, they lack the ability to generate temporal representations of their actions. As a result, schizophrenics may attribute their own actions to the intentions of others. (7)

A similar theory has been proposed to explain the auditory hallucinations that schizophrenics experience. This assumes an analogous relationship between internal speech and motor imagery. The source-monitoring hypothesis states that auditory hallucinations are caused by ascription of internal speech to an external agent. (8) Schizophrenics are not capable of maintaining a firm boundary between themselves and others. They have great difficulty differentiating between themselves, others, and their environment. This is detrimental to their personal identity.

A further area of research might consist of studying the perception of other senses, such as touch in schizophrenic or other psychotic populations. Whether or not it can be characterized as a problem with internal representations as well. This would be useful for creating a more general explanation of motor representation’s relationship to perception. The case of hallucinations is an interesting area where the mental representations clash with perceptions. These examples permit the characterization of mental illness in terms of conflict between conscious and unconscious processes. They generally illustrate that conscious and unconscious are incapable of communicating information correctly. Therefore, potential treatments should seek to facilitate better communication in order to resolve the conflict in brain processes.


1Jeannerod, M. (1994). “The representing brain: Neural correlates of motor intention and imagery.” Behavioral and Brain Sciences, 17 (2): 187-245.

2Jeannerod, M., et al. (1995). “The Cognitive Neuroscience of Mental Imagery.” Neuropsychologia, Vol. 33, No. 11, pp. 1335-1344

3Grobstein P., “Getting it Less Wrong, the Brain’s Way: Science, Pragmatism, and Multiplism.” Interpretation and Its Objects. Ed. Andreea Ritivoi (2003)

4Jeannerod M., Georgieff N., (1998). “Beyond Consciousness of External Reality: A ‘‘Who’’ System for Consciousness of Action and Self-Consciousness,” Consciousness and Cognition, 7, 465– 477

5Jeannerod M., et al. (2000). “Consciousness of Action and Self-Consciousness, A Cognitive Neuroscience Approach,” Agency and Self Awareness : Issues in Philosophy and Psychology, J. Roessler and N. Eilan (Eds). Oxford, Oxford University Press.

6Gallese, V., The Manifold Nature of Interpersonal Relations: the Quest for a Common Mechanism.” Phil. Trans. R. Soc. (2003)

7Maruff P., et al. (2003). “Abnormalities of motor imagery associated with somatic passivity phenomena in schizophrenia, Schizophrenia Research, 60, 2 - 3, 229 – 238

8Maruff P., et al. (2004). “Attention, motor control and motor imagery in schizophrenia: implications for the role of the parietal cortex,” Schizophrenia Research, 70, 2 - 3, 241 – 261 2004

Comments

Paul Grobstein's picture

from horses to hallucinations

From motor imagery to motor representations to interpersonal relationships to schizophrenia and hallucinations makes a very intriguing set of links. Does one need all of them? Can it branch at very points to make sense of other things? What possible research/therapy directions does it suggest?

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