Abstract
In recent years numerous studies documented a key role of neural oscillations in perception and cognition. However, surprisingly little is known about oscillatory activity underlying facial affect recognition. The limited number of studies that addressed this question indicate that gamma oscillations are one key mechanisms underlying this process. The present study aimed to further elucidate the role of neural oscillations within the gamma range in facial emotion recognition in healthy adults by using transcranial alternating current stimulation (tACS) to transiently modulate cortical oscillations while participants completed facial affect and facial identity tasks. In Experiment 1, participants (N= 24) completed a same-different emotion recognition task while tACS in the beta range, gamma range, or sham stimulation was delivered over the visual cortex. Statistical analysis revealed that gamma stimulation resulted in greater accuracy scores. In Experiment 2, participants (N =22) completed two tasks; one examining facial emotion perception and another examining facial identity perception (Cambridge Face Perception Task, CFPT). The first task entailed sorting pictures of the same individual from the least to most angry (faces were morphed between neutral and angry faces in order to contain varying levels of anger). The CFPT required participants to sort pictures of faces according to a degree of similarity between a target face and six images that were morphed between the target face and another person. Each participant completed these tasks twice, while tACS within the gamma range or sham stimulation was delivered. Modulating occipital gamma facilitated processing of facial affect, but did not influence participants' performance on the CFPT. Therefore, delivering tACS in the gamma band via electrodes placed over primary visual cortex selectively enhances facial affect, but not identity recognition.
Meeting abstract presented at VSS 2014