Abstract
The visuo-cortical response to a stimulus increases when it is task-relevant, compared to task-irrelevant. Similarly, stimuli that reliably predict noxious events (threat cues) are amplified at the level of visual cortex. It is unclear how the competition between a task cue and a threat cue are resolved when they co-occur in time and in space. Utilizing electroencephalography and a Pavlovian conditioning paradigm, we investigated the visuo-cortical representation of two simultaneously presented visual stimuli by tagging the stimuli at two distinct frequencies (8.57 Hz and 12 Hz), thereby inducing two distinguishable steady-state visual evoked potentials (ssVEPs) in the visual cortex. Visual stimuli consisted of red and green random dot kinematograms (RDKs) which flickered at the tagging frequencies (e.g. red flickered at 12 Hz and green at 8.57 Hz) and exhibited random motion. Each trial began with random motion for at least 1749 ms, followed by a time range (1750-6996 ms) in which all dots in one or both RDKs could move coherently, for a duration of 1749 ms. In an initial habituation block, participants responded to coherent motion of the green RDK with a key press. Coherent motion of the red RDK in the subsequent acquisition block predicted a noxious noise, while participants still responded to green coherent motion targets. The amplitude of the ssVEPs for both red and green tagging frequencies increased from the habituation block (no loud noises) to the acquisition block, during random motion as well as during coherent motion. Across conditions, threat cue (red RDK) amplification from habituation to acquisition was not at the cost of green RDK amplitude, which also increased. Results suggest that task stimulus processing in visual cortex is not diminished when competing with a temporally circumscribed threat cue, presented at the same time and in the same position as the task cue.
Meeting abstract presented at VSS 2018