Modulation of neuromagnetic responses to face stimuli by preceding biographical information

When we encode faces in memory, we often do so in association with biographical information regarding the person. To examine the neural dynamics underlying such encoding processes, we devised a face recognition task and recorded cortical activity using magnetoencephalography. The task included two conditions. In the experimental condition, face stimuli were preceded by biographical information regarding the person whose face was to be memorized, whereas in the control condition, nonsense syllables were presented before face stimuli. Behavioral results indicated that the biographical information about a person facilitated the recognition memory of their face. Magnetoencephalography signals showed clear visually evoked magnetic fields mainly in the occipitotemporal cortex, in response to the face stimuli that were to be encoded. The phasic peak was observed at 100-200 ms after onset of a face stimulus, which was followed by late latency deflections (200-400 ms). Comparison of the signal between conditions revealed that the preceding semantic information does modulate the neuromagnetic responses to the face stimuli. This modulation occurred primarily at the late latency component in the sensors over the occipitotemporal cortex. In addition, the effects of conditions were also observed in the signals from more anterior sensors, which occurred earlier than the effects in the occipitotemporal cortex. These results provide insights into the neural dynamics underlying the encoding of faces in association with their biographical information.