ABSTRACT
Auditory event-related potentials (ERP) were registered to the dichotically presented white noise stimuli (duration 1500 ms, band 150-1200 Hz). Abrupt or gradual change ofinteraural time difference in the middle of stimuli (750 ms after sound offset) was perceived as an apparent auditory image (AI) instant relocation or motion from the midline to one of the ears. In responses these stimuli two ERPs were observed: one to the sound onset, and second--to the onset of motion or AI relocation. ERPs to AI relocation differed from those to sound onset in longer components latencies (123 ms versus 105 ms for N 1,227 ms versus 190 ms for P2). In responses to AI motion component latencies were even longer (N1: 137 ms, P2: 240 ms); N1 amplitude was greater at sites contralateral to the AI motion direction.
Subject(s)
Evoked Potentials, Auditory , Sound Localization , Acoustic Stimulation , Adult , Female , Humans , Male , MotionABSTRACT
We report here studies of the efficiency of recognition of short acoustic signals (11-30 msec) whose presentation did not produce mismatch negativity in evoked potentials in the human brain. Nonetheless, stimuli could still be recognized efficiently in these conditions; processing negativity disappeared from evoked potentials and the efficiency of recognition was significantly worsened on presentation of the shortest stimuli (11 msec). It is suggested that processing negativity also has a critical duration for acoustic signals, though this is significantly shorter than the minimum duration of stimuli needed for generating mismatch negativity.
Subject(s)
Acoustic Stimulation , Auditory Perception/physiology , Brain/radiation effects , Evoked Potentials, Auditory/radiation effects , Recognition, Psychology/radiation effects , Acoustic Stimulation/methods , Brain/physiology , Electroencephalography/methods , Evoked Potentials, Auditory/physiology , Humans , Reaction Time/physiology , Recognition, Psychology/physiology , Time FactorsABSTRACT
We found that the mismatch negativity (MMM) was absent in evoked potentials in passive condition for frequency deviant acoustical stimuli when stimulus duration was only 11-30 ms. But it was shown that it is possible for participants to fairly well discriminate these stimuli and the component N2b in RP was generated without preceding MMN. Processing negativity also was absent in potentials by the minimal stimulus duration (11 ms). Auditory discrimination nevertheless was still possible, but reaction time and number of committed errors increased significantly.
