Neuro term. 1. Total or partial loss of the ability to carry out learned body movements (e.g., whistling, clapping one's hands, and tying shoelaces), despite the presence of a healthy sensory-motor nervous system. 2. Inability to plan body movements, rather than problems carrying them out.
Usage: In a conversation, higher-level gestures (e.g., mime cues) mark the presence of conceptual thought. Seeing a steeple gesture in a listener, e.g., indicates a thoughtful (rather than an emotional, disagreeing, or uncertain) response to a speaker's remarks. Studies of apraxia suggest the neurological reasons for this view. Mime cues, such as imitating the act of threading a needle (unlike lower-level emotionalgestures, such as expressing anger with a table-slap), are controlled by neocortical areas of the parietal and left frontal lobes--areas also used in speech.
RESEARCH REPORT: Higher-level learned gestures and spoken words are both mediated (in right-handed individuals) by premotor areas of the left frontal neocortex. Mime and steeple cues are controlled a. by a hand-skills area (located immediately anterior to the primary motor area for the digits and hands), and b. by Broca's area (traditionally associated with speech). As in proper grammatical speaking, our most complex hand gestures (e.g., miming the manual process used to make a stone tool) depend on prefrontal control to achieve the proper sequence of steps in the manufacturing process. (N.B.: Damage to the left frontal lobe not only causes apraxia but also a related speech defect known as aphasia.)
E-Commentary: "In my work with dyspraxic kids I have found it useful to think about how their reflexes develop in utero and through the first few years of infancy. Reflexive maturation is manifestly not achieved in dyspraxic children, the more primitive precursors often being readily elicited. For example, several teenagers I have met have not matured their startle response (Strauss reflex) to what you accurately describe and retain an active Moro (primate infant grasping) response as evident in newborn babies. The excellent summary "A Teacher's Window into the Child's Mind," by Sally Goddard, Fern Ridge Press, Oregon, gives an introduction for keen observers as to anomalous and difficult to decipher physical movement in adults. Hope this might help. --M.C., U.K. (8/4/01 3:01:31 PM Pacific Daylight Time)
Neuro-notes. "The most commonly noted error of IMA [ideomotor apraxia] is using body part as object, for example, using the index finger as if it were the shaft of a screwdriver [rather than using the fingers to 'turn' the imagined shaft]" (Watson et al. 1992:685).