Jeannerod, Marc. ”The Cognitive Way to Action."
In “The Cognitive Way to
Action,” Marc Jeannerod describes research on the generation of voluntary
action. He begins with an historical overview of theories in the field. Already
in the 1930s researchers noted that even the simplest movements produced by the
nervous system of a frog appeared to be organized purposefully. So the question
was, How are these actions represented in the brain? An important advance was
the recognition that behavior is guided by internal models of the external
world, with predictions built in as to how the external world will be modified
by the organism’s behavior and how the organism itself will be affected by the
action. The existence of such models is supported by ethological studies
showing that certain behavioral sequences unfold blindly and eventually reach
their goal after they have been triggered by external cues. Localized brain
stimulation can also trigger similarly complex actions.
Early accounts hypothesized
serial steps in the neural generation of actions. However, current brain
studies suggest simultaneous activation in cortical and subcortical levels of
the motor system. This distributed model of action-generation raises the issue
of a central coordinator to determine the temporal structure of the motor
output. The behavior of patients with damage to the frontal lobes suggests to
Jeannerod that the supervisor system is associated with this region.
New light is now being shed
on the problem of the neural substrates of action-generation by the study of
mentally-simulation action. Jeannerod and his colleagues instructed subjects to
imagine themselves grasping objects. Using Positron Emission Tomography (PET)
and functional Magnetic Resonance Imaging (fMRI), they identified the cortical
and subcortical areas involved. They were then able to show that forming the
mental image of an action produces a pattern of cortical activation that
resembles that involved in intentionally executing the action.
Jeannerod expects research
such as this to shed light on the neural underpinnings of central aspects of
the self such as intentionality and self-consciousness. He notes that there is
now neuropsychological evidence for the moral dictum that “to intend is to
act.”
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