NVESTIGATION OF EEG SIGNAL RESPONSE USING EVENT RELATED POTENTIAL (ERP) TOWARDS ISHIHARA ISOCHROMATIC VISUAL STIMULUS

• Main Author: Wicaksono, Andrey
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49244
• Institution: Institut Teknologi Bandung

Electroencephalogram (EEG) is an extracellular flow that arises from electrical activity on neuron sheets in the cerebral cortex as a sign of a cognitive process in the brain. Visual signals are transmitted from cone cells and rod cells in the retina of the eye to the primary and secondary visual cortex. Cone cells are receptors in the eyes that are very sensitive to color. Whereas rod cells are sensitive to light contrast. Cone cells consist of three types of depending on color sensitiveness, namely red, green, and blue cone cells. Each cone cell has the ability to receive different wavelengths of light. The primary visual cortex receives visual signals from the eye. This cortex is located in the medial area of the occipital lobe which is in charge of processing information on visual shapes and patterns. Then the signal is transmitted to the secondary visual cortex for analysis of visual details and understanding of visual meaning. Someone who has a certain number of cone cells that is lacking is called color vision deficiency. While the loss of one type of cone cell referred to as partial color blindness. The survey of the spread of color blindness in European and Caucasian races of men and women is around 8% and 0.4%. In ethnic Chinese and Japanese men are around 4% and 6.5%. Color blindness in a person can mostly occur due to the event founder or genetic drift. People with red-green color vision deficiency and partial color blindness have difficulty seeing hidden numerical information in the images from the Ishihara test book, this is because they have a number of cone cells that are lacking or missing, thereby reducing eye sensitivity to color. The Ishihara test is a visual test that is used to detect the type of color blindness in a person. Event-Related Potential (ERP) is an alternative method of noninvasive, electrophysiological techniques that can provide accurate millisecond data about sensory and cognitive processes related to an event or information from a given stimulus, besides ERP is also used to measure the cognitive function of the brain. The basic question in this study is that although the partial color-blind people have difficulty seeing the information numbers hidden in each picture in the Ishihara test book, due to the cone cells in their eyes cannot detect a red or green color, does this also affect their cognitive function. Thus, this study aims to investigate the response of EEG signals between normal v people and partial color blindness using ERP methods, especially when they are given visual stimulation in the form of images from Ishihara's book. In this study, first, the occurance of ERP components will be searched using the GFP (Global Field Power) method. Then, the significant difference of ERP amplitude was found in each range of ERP components by using the T-Test statistical analysis. Brain topographic analysis to see cortical distribution will also be used to strengthen the results of ERP method analysis. The results of the ERP method in this study can show the brain response of partial color-blind people and normal people. ERP components at 200 ms latency (N200 and P200) did not show a significant difference. However, significant differences were found in the ERP component of 300 ms (P300 and N300) in the temporal section ie channels P7 and P8, as well as 400 ms (P400 and N400) on the O2 channel. These results are strengthened by the results of the functional topography of the brain, at latency of 200 ms, both groups showed responses with similar patterns of distribution of brain maps. However, at latency of 300 and 400 ms significant differences appear in the inferior and temporal brain. These results indicate that both groups have changed the initial visual process at 200 ms latency. At latency of 300 and 400 ms associated with advanced visual and cognitive processes associated with numerical information between normal people and partially color-blind people are also different.