Spatiotemporal Decoding Of Multidimensional Information Within The Human Face ——Evidence From EEG And FMRI

Humans can detect and recognize faces quickly,but there has been little research on the dynamics of the different dimensional face information that is extracted.This study systematically reveals the precise process of facial information processing by comprehensively considering different dimensional face information such as age,gender,emotion,and identity.Experiment 1 is an EEG experiment,in which the EEG signal of each subject to different faces were obtained through a 1-back task and then decoded using support vector machine to obtain the representational dissimilarity matrices of different faces for each subject.Then,the representation similarity analysis was performed with the model representational dissimilarity matrices containing different dimensional face information,and the time course of neural responses to different dimensional face information was measured.The results indicated that facial emotion processing occurred before identity and lasted for a long time,and the arousal processing occurred before valence.Experiment 2 is a f MRI experiment,in which the brain activation representations of different subjects on different faces were obtained by f MRI as the subject identified different faces.Multivariate pattern analysis was performed on some selected brain regions to obtain the representational dissimilarity matrices of f MRI,which was then compared with the model representational dissimilarity matrices for representation similarity analysis to reveal the details in which different dimensional face information were processed in the brain.The results suggested that there were differences between brain regions that process different dimensional face information,with processing of facial emotion occurring mainly in the right frontal region.Through these two parts of the experiment,we explored the processing manner of different dimensional face information in the brain through temporal and spatial respectively.The following conclusions are drawn:1.There are differences in the processing time and brain regions of different dimensional face information.The processing of emotion occurs before identity,and the right frontal region being specific for emotional processing.2.In the process of facial emotion processing,arousal is processed first,while valence is processed later.There are also differences in the processed brain regions of these two dimensions of information.