| We see different image on each eye usually. Brain integrates the information that project into eye to create a single continuous and stereoscope visual scene. What if image project into each eye conflict? What experience and perception occurs by this kind of stimulus? Instantly, many people think our brain still try to integrate two images into a single or selected one of them. However, it?s not true. The picture alternate between eyes, one eye percept a period of dominant picture, while the picture project into the other eye was suppression, then perception alter between dominant perception and suppression perception period. This is binocular rivalry(BR).Binocular rivalry is considered a useful method for investigating the processes underlying perceptual selection and visual awareness, as stable input(the same images shown constantly to each eye) leads to alternating conscious percepts. Thus, binocular rivalry can be used to examine such questions as:1. The locus of awareness: At what stages within the visual processing hierarchy do neural events correlate with conscious experience?2. Perceptual selection: How does the brain resolve competition between stimuli and choose which one to bring into awareness?3. Unconscious processing: What aspects of an image that is suppressed from awareness can nonetheless be processed, and how can such processing affect behavior?The study use BR has been widely used in outer physical stimulus and interfere of outer event on visual perception, subject instinct factor. Early BR study focus on behaviors report which is subject, this kind of measure has more deviate. BR combine EEG, f MRI contribute to the neurophysiological study of BR recently.The factor that restricts the use of EEG on the use of BR partly result of distinct perception from EEG signal is difficult. Steady state visual evoke potential(SSVEP) is a sort of EEG that related to visual stimulus, when subject was stimulus by a visual stimulus on specific frequency, brain can be record a continuous same frequency potential on the visual cortex, this potential was called SSVEP, we use SSVEP as the tag of different image that was percept and measure the perception of BR objectively.Continuous flash suppression is a kind of non-balance BR and use to create a stable unconscious. Break continuous flash suppression can be used in the study of high lever recognize function under unconscious, in which, the contract of suppression image increase gradually until the image break suppression perception and be awareness. High lever recognize function include mathematic, face recognize, word recognize. There is a debate on the mechanism of word process unconscious and whether other kind of perception has influence on unconsciousness.Base on above analysis, this study build up a SSVEP system and invested the sentiment frequency of subject. On this basis, we use binocular rivalry estimate objectively under face awareness and fusiform correlation analyze, subsequently, we use CFS to invested word semantic analyzes which is a high level recognize process and cross channel influence under unconsciousPart 1: Building up SSVEP system and filtering of sensitive frequency on subjectFor the combine of SSVEP and BR, in which SSVEP was used as the tag of stimulus. We build up a SSVEP system. Hardware system consist of biology potential amplifier, electrode map, LED screen, computer. Different flicker frequency was control by LED screen write by C++, interfere main pragmas has the function of reading, measuring independence, controlling experiment process, data recording. On this basis,we filter sensitive frequency of stimulus, result show our SSVEP system is stable and work well, on this part of experiment,we select SSVEP blink and SSVEP sensitizer, observe the distribute of sensitive frequency. This system was used in the study combine BR. Part2: Binocular rivalry estimate objectively under face awareness and fusiform correlation analyzeTo study binocular rivalry(BR) objectively and correlation between fusiform face area and visual cortex,six subjects participated in this study, with one eye presented a normal face expression picture flickering at 8.57 Hz, while the other eye presented a fearful face flickered at 12 Hz or 15 Hz respectively. EEG was recorded during this process. SSVEP that evoked by two flickering rate was analyze by time-frequency analysis of FTFT. We estimated time index of BR and compared the correlation coefficient between FFA and visual cortex. The total average time of left eye was 411.6±73.8ms and right eye was 547.6±126.7ms, switch rate was 2.11±0.28 Hz, left FFA is more sensitive than right FFA in process of fearful face, both sides of FFA have no frequency preference to flickered fearful face. SSVEP could be used as the frequency tag of BR. SSVEP can be used as the tool to evaluate visual sensation under BR objectively and the pattern of SSVEP combining BR can be used in research of neural mechanisms of visual awareness. Part3: the study of unconscious processing of semantic high level recognize function Tactile sense of frequently-used tool and temperature do not influence unconscious processing of Chinese wordsSemantic processing is a high level cognition function of human brain. Continuous flash suppression(CFS) could be used to study unconscious semantic processing and tactile factors that have impact on it. In experiment 1.and experiment 2.Subjects in the two experiments were required to response immediately after observing the words by pressing keyboard correctly. Analysis didn?t detect significant difference in reaction time(RT) with or without tactile stimulus in the two experiments, or between upright and inverted word group. These results support the view that semantic information is not processed unconsciously. Tactile of shape of frequently-used tool and temperature do not assist in breaking continuous flash suppression earlier. Considering that behavioral research can?t reflect precision biological change or that semantic processing may not occur in the absence of awareness, we use EEG to prove that. High level Semantic analysis(N400) does not occur in the absence of awarenessIt has been intensely debated whether visual stimuli are processed to the point of semantic analysis in the absence of awareness. In the present study, we measured the extent to which the meaning of a stimulus was registered using the N400 component of human event-related potentials(ERPs), a highly sensitive index of the semantic mismatch between a stimulus and the context in which it is presented. Observers judged the semantic relatedness of a context and target word while ERPs were recorded under continuous flash suppression. We found that the amplitude of the N400 was no different under different group(related and unrelated), this indicate that observers could not discriminate the meaning of suppressed. Our results(N400) support the ideal that semantic analysis do not exist in the absence of awareness It is more proofs from different techonologise that need to get a more logical conclusion. |
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