Title: Tests results on Parkinsoní s disease by means of a new equipment with virtual reality support
Author: prof. Alberto Rovetta N. AD-3

Da Silva, H. Lopes. Spatio-temporal analysis of brain signals, in Workshop: ďDetection and Multimodal Analysis of Brain weak Signals to Study Brain Function DiseaseĒ, Politecnico Milano, 1997

The velocity of execution of the movement follows the tendency to diminish with the age, in accord with the reaction time which is proportional to the age. This fact demonstrates in a correct way that the time of reaction and the velocity are variable, depending on the age. By considering all the data obtained by the tests, both on healthy persons and on unhealthy persons, the tests with virtual reality too show that the velocity of the phalanxes is one of the more expressive data that characterise the behaviour of the people.

Mechanical information such as position, velocity, pressure distribution, force are required for a better knowledge of human behavior as well as of human kinematics and contact movements, while sensory systems can provide methods and tools to achieve comfortable man-machine interfaces. Human sensory fusion has been analyzed by means of virtual reality interfaces. Feedback is made possible by the visual and acoustic control of the executed performances. The visual perceptions are processed by the cerebral cortex and from the lobes: the occipital one in case of visual signals and the temporal one in case of acoustic signals. The subject has the control of his action; this fact is made possible by the signals, which depend from the occipital and temporal lobes, and which are consequently integrates in all the motor circuits. The sensitive perceptions come from the cortical (occipital and temporal) protective areas, pass to the motor circuits of the control loop, which include thalamus and base extrapyramidal ganglia and cerebellum, and then they connect to the cortical-spinal executor system.

The protocol of tests has been performed on the healthy people; on people affected by Parkinsonís disease, the test were made in normal conditions and repeated on the same subjects after the assumption of a specific medicine (apomorphine) that acts on the centres of the neural system. The followed protocol foresees a sequence of three tests repeated for three times; the average values are considered. The analysis of the tests performed according to the established protocol of three tests for each type of movement, present the following characteristics, highlighted in the graphical drawings. The reaction time in the majority of the patients has low changes, with respect to the values of the healthy persons in the same range of age; a small worsening is audited. It is necessary however to underline that the reaction time line (increasing or decreasing) does not change in relation with the age, as happens with healthy persons, but is correlated chiefly with the state of advancement of the disease.

Future possible developments
For the analysis and evaluation of the results, it is relevant that the comparison among the data on the two different typologies of personís (healthy and sick) shows that the values of velocity of the healthy persons are higher than those of the persons affected from the Parkinsonís disease.