G. Dennis Rains,
Kutztown University of Pennsylvania
| akinesia | Absence of movement.
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| athetosis | Ceaseless occurrence of slow, sinuous, writhing movements performed involuntarily.
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| ballism | Involuntary, violent flinging movements of the extremities.
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| basal ganglia | A large group of gray matter structures deep within the forebrain including the caudate nucleus, putamen, globus pallidus, subthalamic nuclei, and substantia nigra. (The substantia nigra is actually in the midbrain.) This term is an exception to the general rule that collections of neuron cell bodies within the cen-tral nervous system are called nuclei, whereas those in the peripheral nervous system are called ganglia.
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| bradykinesia | Slowed movement.
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| caudate nucleus | One of the nuclei of the basal ganglia.
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| cerebellar ataxia | Disruptions in the mainte-nance of posture and the sequential coordina-tion of movement associated with cerebellar dysfunction.
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| cerebellum | The large and intricate structure bulging out of the dorsal surface of the brain at the level of the pons and forming the roof of the fourth ventricle.
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| chorea | The ceaseless occurrence of a wide variety of rapid, complex, and jerky movements that may appear to be well coordinated but are involuntary. Choreic movements are seen in a number of different diseases of the nervous system.
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| cogwheel rigidity | A disorder characterized by movement that appears cogwheellike to the examiner when the patient's limb is moved passively.
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| conceptual apraxia | Impairment in the use of an object due to disruption of the conceptual knowledge of the relationship between the object and the movements appropriate to it (as opposed to disruption of the programming of the necessary movement, which is intact). This manifests itself as preserved ability to carry out sequences of learned movement, but doing so in ways that do not correspond to the situation, such as picking up a hammer and making movements appropriate for the use of a saw.
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| directional tuning | The range of movement over which a particular M1 neuron fires.
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| direction vector | A line representing the characteristics of a particular M1 neuron for a particular movement. The line's length represents the relative firing rate of the neuron and its direction represents the cell's preferred direction.
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| dissociation apraxia | A proposed category of apraxic disorders characterized by marked dissociations, under different testing conditions, in the ability to execute learned movements. An example of such a dissociation would be impairment in demonstrating the movements involved in using an object when the object is absent, together with preserved ability to demonstrate the use of the object when it is placed in the hand.
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| dysmetria | Impairment in moving a limb so that it accurately reaches a target. Seen after cerebellar lesions.
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| dyssynergia | The activation of the muscles required for a movement but not in a coordinated, synergistic manner. The result is a decomposition of what would normally be a coordinated movement into individual components. It is seen in association with cerebellar lesions.
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| expressive gestures | Actions that communicate emotion more directly than symbolic gestures, such as shaking one's fist.
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| globus pallidus | One of the nuclei in the basal ganglia.
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| hemiballism | Involuntary, violent flinging movements of the extremities on one side of the body.
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| hemiparesis | Impairment in fine-motor behavior and muscular weakness on one side of the body.
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| hyperkinesia | Unintended and unwanted movements.
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| hypokinesia | Diminished ability to move the body.
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| ideational apraxia | According to classical terminology, impairment in the ability to perform acts that involve complex sequences of movement, with preserved ability to perform individual movements and actions.
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| ideomotor apraxia | According to classical terminology, impairment in the ability to perform spe-cific learned motor acts not due to paralysis or weakness.
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| limb apraxia | An apraxic disorder that affects the limbs, particularly the hands, but does not involve the mouth and tongue.
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| motor apraxia | Term used by Liepmann to indicate impairment in fine-motor coordination (not due to weakness or paralysis) resulting from a cerebral lesion.
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| motor cortex (M1) | The area of cortex (just anterior to the central sulcus) that is most directly involved in the implementation of movement. Also called M1.
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| movement formulas | Liepmann's hypothetical cerebral representation of learned movements, which he believed to be localized in the left hemisphere.
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| neostriatum | The caudate nucleus and the putamen.
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| nigrostriatal bundle | A fiber tract projecting from the substantia nigra to the neostriatum.
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| oral apraxia | An impairment in the execution of learned movement (not due to peripheral motor or sensory impairment) that selectively affects the individual's mouth and tongue.
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| paraplegia | Paralysis of the legs resulting from a lesion of the spinal cord.
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| parietal lobes | The area of cortex and underlying white matter lying beneath the parietal bones, at the posterior, superior part of the skull.
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| population vector | The sum (in terms of direction and magnitude) of the direction vectors of neurons in M1 associated with a particular movement. The direction of the population vector is very close to the direction of actual movement.
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| praxicons | Hypothetical neural representations of learned movement in the left parietal lobe. Also called visuokinesthetic engrams.
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| preferred direction | The direction of movement being made (or about to be made) that is associated with the maximum firing rate for a particular neuron in M1.
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| prefrontal cortex | The area of the frontal lobes anterior to the premotor and supplementary motor cortices. It is involved in the higher-order control and regulation of behavior.
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| premotor area (PMA) | The area of cortex just anterior to the motor cortex on the anterior surface of each cerebral hemisphere. It is involved in the coordination of sequences of movement.
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| putamen | One of the nuclei that make up the basal ganglia.
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| quadriplegia | Paralysis of the legs and arms resulting from a lesion of the spinal cord.
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| resting tremor | Tremor in the limbs when no movement is being performed (during rest).
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| somatosensory area (S1) | The area of cortex in the postcentral gyrus of each hemisphere that receives and processes sensory information from the contralateral side of the body about touch, temperature, vibration, proprioception, and kinesthesis.
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| substantia nigra | A midbrain nucleus that is a major source of dopamine for the cortex. It is generally considered to be part of the basal ganglia.
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| subthalamic nuclei | Small nuclei that lie ventral to the thalamus. They are generally considered to be part of the basal ganglia.
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| supplementary motor area (SMA) | The area on the medial surface of each hemisphere just anterior to the motor cortex. It is involved in the coordination of sequences of movement.
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| symbolic gestures | Actions that communicate meaning symbolically, such as showing the thumbs-up sign or waving good-bye.
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| visuokinesthetic engrams | Hypothetical neural representations of learned movement in the left parietal lobe. Also termed praxicons.
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| whole-body movements | Movements involving the entire body, such as standing in the pose of a boxer or walking across a room.
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2002 McGraw-Hill Higher Education