Table 2.
Event-related potentials paradigm: main psychophysiological and neurochemical significance.
| Paradigm | Description | Significance |
|
|---|---|---|---|
| Psychophysiological | Neurochemical | ||
| Multi-deviant mismatch negativity (MMN) | Three consecutive blocks of acoustic stimuli were delivered binaurally via earphones. Each block consisted of a sequence of rapidly repeated standard acoustic stimuli occasionally interrupted by a rare deviant sound (a different one for each block) with a probability of 0.1. All the stimuli consisted of sinus tones (rise-fall times: 5 ms): the standard tone was 1000 Hz (duration: 150 ms; intensity: 80 dB-SPL); deviant 1 was different for its frequency (1150 Hz), deviant 2 differed from standard tone for duration (100 ms), deviant 3 differed for intensity (90 dB). The inter-stimulus interval (ISI) was fixed on 500 ms. Each block, comprising 500 stimuli, lasted about 10 min. The subjects, who were required to watch a silent movie during the task, were unaware of the occurrence of the different tones | Pre-attentive discrimination; sensory–memory updating; and change/rule violation detection (13) | NMDA receptor (14, 15); dopamine (16, 17); serotonin (18) |
| P300 auditory two-stimuli (oddball and motor response) | Auditory stimuli, consisting of pure tones of 200 ms duration (rise-fall times: 0 ms) and intensity of 80 dB-SPL delivered binaurally via earphones, were administered in two consecutive blocks during the same session. During each block, which consists of 150 trials, 2 tones were administered: standard stimuli (1000 Hz) and target stimuli (2000 Hz) that occurring randomly with a probability of 0.33. During the first block, the subjects were instructed to recognize the target stimuli by mental counting; during the second block they had to push a button as quickly as possible upon hearing the target tones. Inter-trial interval varied randomly between 3 and 6 s | Selective attentional processing; memory storage (19) | Norepinephrine (20); dopamine (21) |
| Contingent negativity variation (CNV) | It is evoked whenever a close temporal relationship between two-stimuli, i.e., “warning” and “imperative,” is established. The warning and imperative stimuli consisted, respectively, of a light flash of 100 μs–1.5 J (S1) (delivered by a strobe lamp at a distance of 30 cm from the subject) and, 1750 ms later, a sound at an intensity of 80 dB-SPL, lasting 200 ms, randomly presented at either 1000 or 2000 Hz (S2). Subjects were instructed to push a button with the right index finger as quickly as possible upon hearing the 2000-Hz sound. The inter-trial interval varied randomly between 5 and 10 s. A total of 100 trials were acquired | Alertness response; sustained attention during an operative conditioning (22) | Norepinephrine (23); dopamine (24) |
| Intensity dependence of auditory evoked potentials (IDAP) | Auditory evoked potentials were evoked by an acoustic stimulation consisted of four runs of 250 stimuli each with the inter-stimulus interval being randomized between 500 and 900 ms. Tones of 1000 Hz and 50 ms duration (rise and fall times: 10 ms) were delivered binaurally through earphones at four different intensities (60, 70, 80, and 90 dB) in a pseudo-randomized order. The sounds were presented and controlled by a PC running system. The subjects were not informed about the sequence of different tones and were instructed to ignore themselves. For each intensity level, at least 150 trials were collected | Serotoninergic central tone (25) | Serotonin (25) |