Poster #: 96
Friday, Sep 11, 2015
Temporal regularity is encoded in the human auditory brainstem
Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Spain;niversity of Barcelona, Spain;, Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Catalonia-Spain;, Barcelona, Spain
The temporal regularity of sensory stimulation is of prime importance for our online behavior, as it helps to optimize detection and processing of incoming events. The mismatch negativity (MMN) of the human event-related potentials is elicited by violating a regular stimulus onset asynchrony (SOA) of auditory sequence. Importantly, deviance-related responses can be also find in the middle-latency response (MLR) range, circa 30-40 ms from the deviance onset. The aim of the study was to examine the effects of fine-grained violations in the rhythmic structure of auditory stimulation in the human brainstem using frequency-following responses (FFR). We presented amplitude modulated sine waves (carrier frequency 2530 Hz, symmetrical triangle-wave modulation with frequency f0 = 390 Hz) in a multi-oddball paradigm. Standard stimuli were presented at a constant rate of 3.21 Hz (i.e. at multiples of 312 ms from the onset of experimental block), whereas 8 equiprobable deviants (p = 0.16) in order to break the temporal pattern were presented at different phases of the presentation cycle, -π, -¾π, -½π, -¼π, ¼π, ½π, ¾π, π, i.e., with SOAs 156, 195, 234, 273, 351, 390, 429 and 468 ms, respectively. A sequence not entailing a rhythmic organization was used as a control condition. Our preliminary results showed that the FFR at the stimulus modulation frequency f0 differ significantly in its mean amplitude (p = 0.008) in oddball vs. control condition, suggesting that the human brainstem is able to encode the timing regularity of auditory landscape.