Poster #: 69
Topic: Memory and perception
Friday, Sep 11, 2015
The role of adaptation in the mechanisms underlying visual mismatch negativity
1Cognitive Neuroscience Research Group 1., Institute of Cognitive Neuroscience and Psychology, RCNS HAS, Budapest, Hungary
2Institute of Cognitive Neuroscience and Psychology, RCNS HAS, Budapest, Hungary
3Cognitive Neuroscience 1, Institute of Cognitive Neuroscience and Psychology, RCNS HAS, Budapest, Hungary
The vMMN, a negative ERP component in the 120-300 ms latency range, considered as an "error signal” is elicited by deviant stimuli, that violate sequential regularity. The processes underlying vMMN are ambiguous, because stimulus-specific adaptation add up with the “genuine” mismatch. We investigated the contribution of adaptation to the vMMN. Irrelevant windmill stimuli were presented sequentially with different numbers of vanes (6 and 12), while the participants were played a video game. Two main conditions were applied, an oddball condition, and an adaptation condition with long adaptor stimuli, followed by different test stimuli. As control conditions, homogenous sequences were presented; in these sequences the test stimuli were identical to the adaptor. In the adaptation sequences average duration of the adaptors matched with the average of the summed duration of the standards between two deviants. We compared ERPs to physically identical test stimuli from the heterogeneous and homogenous sequences, and the ERPs to the deviant and standard of the oddball sequences. Deviant minus standard difference potentials of the oddball emerged in two latency ranges; earlier (100-180 ms) and later (200-220 ms) posterior negativities. In the adaptation condition, only the early difference was present (100-180 ms). In the early range, the amplitudes of the adaptation-related and the oddball-related difference waves didn’t differ from each other. Based on our results, we propose that the earlier difference can be considered as stimulus-specific adaptation effect, whereas the later difference reflects “genuine” mismatch, related to the violation of sequential regularities.