Preliminary Study Of Central-defect Visual Field Detection:an ERP And ERO Research

Purpose:To detect the electroencephalogram character of visual stimuli in different location.The event-related potential(ERP)and event-related oscillation(ERO)are adapted as indicators.To explore the location factor features in electroencephalogram,and to provide subjective means in forensic clinical identification.Method:We conducted the experiment in two sections:Section l,classical oddball paradigm.For target stimuli,a black disk was overlaid in the central visual field of checkerboard,namely,the peripheral visual field was checkerboard.The experiment consisted of four degrees of visual field level,which were 5°,10°,200 and 30°,corresponding to the central checkerboard or black disk.separately in distractor stimuli or target stimuli.Forty students were asked to press a button with their right index finger on a keyboard as soon as the target appeared.Behavior and ERP data were collected.Section 2,single spot stimuli.We choose a total of thirteen luminous spots in 5°、10°、20°、30°、40°、50° and 60° visual field level,and their location and physical parameter were constant.Seven participates with their dominant eyes were verified for five times,and ERO data were analyzed.Results:Section 1(1)behavior results.Reaction time and correction rate revealed a prolonged and decreased tendency from 5° to 30°.(2)ERP results.There was no significant effect concerning visual field level in peak latency and mean amplitude,in four degrees of central visual field deficit.The consolidated decreasing trend in amplitude for all positive components including PI,P2 and P3 were observed from 5Oto 300.respectively for PI and P2 in temporal-occipital area and P3 in central-parietal area.Following difference wave assessment showed an inversely tendency to above positive components regarding visual mismatch negativity(vMMN)component.There were no statistically significant for other components and peak latency.Section 2(1)We conducted analysis on the whole data in ASA software.Results indicated that energy were strongly increased in theta or alpha band,and there were distinct lateralization in high frequency band.(2)ERO results indicated that all subjects were strongly activated in theta band in O1,OZ and O2 electrodes.However the variation tendency were different for each subjectConclusions:(1)With the increasing of central visual deficit,subject revealed a prolonged trend in reaction time and an increasing error rate.(2)ERP could reveal the degree of central visual field deficit to some extent.(3)The energy in theta band could indicate the visibility of a point to some extent.