New Training Forms for Rehabilitation of Visual Cognitive Functions
R. Lukauskiene(1), V. Viliunas,(2) A. Jasinskiene(1), and K. Gurevicius(2)
(1) Neurosurgical Clinic, Kaunas University of Medicine, Kaunas LT 3007, Lithuania;
(2) Vilnius University, Sauletekio 9, Vilnius, Lithuania
Abstract:
Visual cognitive function disorders impair persons ability to identify colour and recognize various objects, figures and letters because of that, that brain damage can impair elementary visual functions as well as higher - cognitive visual abilities. These persons need early and systemic rehabilitation. In order to test the possibilities of color perception and other visual cognitive functions, special visual computerized programs were created by using IBM. The current study examined the effect of treatment and rehabilitation in persons after stroke, brain trauma, degenerative processes etc. It seems that computer aided examination and rehabilitation helped to gain some abilities to restore visual perception disorders in persons with some type of brain damage.
Introduction
There is considerable evidence that neural pathways are involved in the processing of different visual features. The ventral occipito-temporal system is implicated in the processing of features relevant to the identification of objects, such as color or shape, and the dorsal occipito-parietal system is concerned with the selection of the spatial characteristics of visual stimuli, such as their location in space.
Brain damage can impair visual acuity as well as higher cognitive visual abilities. In order to test such disabilities we simulated computerized programs for detection of visual perception disorders: test of evaluation of sensitiveness to a certain colour of spectrum, and computerized Munsell 100 Hue test. As visual perception abilities are needed for everyday life of persons which have had derangement of visual cognition and defects of peripheral visual field or visual acuity, it seems that computer aided testing and learning helps to gain some possibility to restore visual perception disorders in persons after some neurological – neurosurgical diseases: strokes, tumors. intracerebral hemorhagias, degenerative processes etc.
Methods
Medical computer aided testing and learning programs for persons with some kind of visual perception disorders have been undertaken by using PC IBM in Neurosurgical Clinic of Kaunas University of Medicine. Test programs were made from various kinds of moduls which performed different functions.
We purposed to work out the new computerized tests which can be used to diagnose the kind of colour perception disorder, to measure the zones of colour confusion of colour defective persons, to train and rehabilitate patients with various degrees of visual perception defectiveness and to perform computerized data analysis of patients which can be treated and trained.
The Farnsworth- Munsel 100- hue (FM 100) test has been used for such purposes:
1. For examination the relationships between deficits in colour and contrast discrimination.
2. To show that impaired colour discrimination is related to pathophysiology of various brain diseases and can be a sensitive method for early detection and monitoring of brain disorders.
3. Can be a sensitive specific and practical method of monitoring colour vision in patients with chronic optic nerve disorders, macular function impairment, opticneuritis, optic atrophy etc. [1, 2, 3, 4].
For testing of colours discrimination, measuring the zones of colours confusion and learning programs of rehabilitation, the computerized Farnsworth-Munsell 100 - Hue test was created and applied to test and rehabilitate patients with various types of brain damage which was verified by means of EEG, CT or MRI.
The type and degree of colour defectiveness was estimated (figure 1).
Figure 1: Computerized Farnsworth - Munsell 100Hue test-1 of four examples
Standard average daylight illumination was used, test was given near the window illuminated chiefly from the north sky. The angle of illumination was about 90 degr. Tested person had to arrange random patterns on the display in order according to the example which was shown earlier and place them that they could form a regular colour series as it was shown on the pattern. It should take about two minutes per pattern. However accuracy was more important than speed.
Results
With computerized Farnstworth-Munsell 100- Hue test [5; 6] examined 127 persons with frontal, temporal and occipital lobe damages which were confirmed by EEG,CT or MRI data, and 39 healthy controls. All examined persons aged from 40 to 65 years old. When interpreting the results total error score was determined.
According to the colour interpretation results all tested persons were devided into 3 groups:
1. Persons with superior colour discrimination when total error scores were from zero to 30.It was taken as the range of superior competence for colour discrimination.
2. Persons with normal discrimination of colours when total error score was between 30 and 100.
3. Persons with average discrimination where total error scores has been found more than 100.
4. Persons with low colour discrimination, when total error score was more than 200.
Total error score till 100 was taken as the range of normal competence for discrimination.
Temporal lobe damaged persons showed the least scores of colour discrimination (mean 187), when frontal (mean 160) and occipital damaged (mean 135). Total error scores of healthy persons showed an average normal colour discrimination (mean 82).
The pattern of colour defectiveness was identified by bi-polarity, a clustering of maximum errors in two regions which were nearly opposite (figure 2 and figure 3).
Figure 2: Normal colour discrimination
Figure 3: Deffective colour discrimination. Deffectiveness of blue colour
The type of colour defectiveness had no correlation between colour defectiveness and topic of brain damage.
By means of the test of colour perception and recognition that we simulated we tested 22 patients after brain traumas and also suffering from the disorders of the perception of colours. When tested and rehabilitated, patients had to choose a colour from the displayed spectrum of colours that corresponded the colour on the left half of the circle, that was also shown on the display. Patients had to fill the circle with the same colour. The spectrum of colours was created from the hue of 3 colours-red, green and blue choosing them by chance and using then various waves lenght. 4 of 12 patients had prosopagnosia. It was stated that blue colour they recognised worse of all-only 22 percent of cases After 12 months rehabilitation one patient restored disability to recognise colours, 3 of them restored their colour perception only 55-60 percent of cases.
Thresholds of colour contrast sensitivity for red, yellow, blue and green stimuli were investigated. We measured contrast sensitivity in 42 persons with right (22 persons) and left (20 persons) brain hemisphere damage with prevalence of temporoparietal lobe. Contrast sensitivity was reduced at high and low frequencies in both groups but significantly it was decreased in low frequencies (0.4-0.9 cycles/ deg.)
Conclusions
By using computerized set of tests for detection of colour vision that we simulated we will continue to test patients with various brain disorders, trying to determine the correlation between the type of colour perception disorder and the corresponding localization of the brain pathology.
As colour perception abilities are needed for everyday life and persons with such disabilities have some problems it seems that computer aided learning helps to gain some abilities to restore colour perception disorders.
References
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The Farnswoth-Munsell 100-hue Test (for the examination of ColorDiscrimination). Manual by Dean Farnsworth. Revised 1957. MUNSELL COLOR, Macbeth, a Division of Kollmorgen Corp.
Nichols B. et al. “Evaluation of a significantly shorter version of the Farnsworth-Munsell 100-hue test in patients with three different optic neuropathies”. J. Neuroophthalmol 1997 Mar; 17(1);1-6.