Cerebral palsy is a condition that results in motor abnormalities as a direct consequence of injury to the developing brain. Fitts' law, which describes a speed-accuracy tradeoff in visually guided movements, has been shown to characterize the motor behavior of normal subjects during aiming tasks. To assess whether Fitts' law can also describe the aimed movements of persons with cerebral palsy, eight cerebral palsied adults participated in an aimed movement study. 12 targets were used with Indices of Difficulty ranging from 2.19 to 6.00 bits. The impact of Gan and Hoffmann's 1988 ballistic movement factor, square root(A) , and Fitts' 1954 Index of Difficulty on subject's movement and reaction times was examined using multivariate linear models. The analysis of the full data set yielded a significant effect of square root(A) on movement times and no significant adherence to Fitts' law. However, high error rates that could be the result of oculomotor problems among the subject group were noted, and the method of handling errors had a large effect on the results. Tracking eye position during a Fitts' law task would provide information regarding the effect of oculomotor difficulties on aiming tasks in the cerebral palsied subject group.

Fitts' Law was applied to the evaluation of discrete aimed arm movements in one dimension performed by 6 adults with cerebral palsy and 6 adults with normal movement. Targets (1.27, 3.81, 6.35, 8.89 cm in width) placed at distances of 20.32, 30.48, 40.64, and 50.80 cm provided Indices of Difficulty of 2.19 to 6.32 bits. A video game was used for the signal to move. The t tests for corrected means showed that the cerebral palsied group had greater reaction and movement times than than the normal group. Linear regression analyses for pooled data and for the individual cerebral palsied subjects showed (a) no relationship between reaction time and Index of Difficulty for either group and (b) a negative, linear relationship between reaction time and Index of Difficulty for 1 cerebral palsied subject. Movement time was linearly and positively related to the Index of Difficulty for the normal group but not for the cerebral palsied group. Two cerebral palsied subjects had movement times which conformed to Fitts' Law. While the exceptions to Fitts' Law may be due to the limited range of movement and spasticity caused by severe cerebral palsy, there are indications that two of the cerebral palsied subjects were performing ballistic rather than visually guided aimed movements. Fitts' Law may still apply when the distances and target positions are individualized to conform to subjects' specific limitations and when the signal to move is auditory rather than visual.

An holistic theory of the functional organization of the central nervous system, a system at the level of the organ, in vertebrate organisms is presented as an alternative to localization of function by using two sets of complementary rules for systems designation derived from systems theory. These rules reveal three types of systems according to levels of operation and the origins of goals. These are: (1) the teleogenic or primary systems (reproductive, food-water intake-use, thermoregulative, immune, oxygen intake-use); (2) the teleozetic or subsystems (internal sensory and motor, external motor, external sensory); (3) the teleonomic systems or echelons (field, local circuit, basic functional unit, basic excitation unit). The systems, subsystems, and echelons are discussed with regard to their hierarchical relationships, the nature of their goals, and the supporting experimental evidence. The theory is discussed as an explicit statement of multileveled relationships for the analysis of the vertebrate CNS and, therefore, as presenting a paradigm for, or a way of thinking about, local and global brain theories, brain dysfunction, and brain evolution.

Monocular pursuit and saccadic eye movements were compared between a group of 5 men with cerebral palsy and a group of 5 men with normal movements using an infrared corneal reflection technique. Triangle, sine, and square waves (in the time domain) at 0.3 Hz in the horizontal and vertical dimensions were used as the stimuli for six 10-sec. tests of each subject. The momentary difference between stimulus and eye positions was used to obtain values for five pursuit variables (triangle and sine wave tests) Land five saccadic variables (square wave tests). The t tests for differences between these means showed that the cerebral palsy group had more fixations during the four pursuit tests, more saccadic intrusions during the horizontal pursuit tests, a greater maximum pursuit error during the horizontal sine wave test, and a greater maximum fixation error during the horizontal square wave test. The group means were not different for pursuit gain and saccadic velocity and latency. The dynamics of the errors during the tests of pursuit movements indicate that cerebral palsied persons may be unable to maintain the constant velocity of eye movement required to track a triangle wave stimulus. The dynamics of the errors during the tests of saccadic movements indicate that cerebral palsied persons would be unable to use technological devices for assisting communication, which depend on visual fixation as a control signal.