CNV resolution does not cause NoGo anteriorisation of the P3: a failure to replicate Simson et al.

For 35 years, some researchers have argued that CNV resolution may affect or even produce the increased P3 for NoGo compared to Go trials, and thus that no 'inhibitory' NoGo P3 exists. This is based on the work of Simson et al. (1977b), the scalp topography of potentials in auditory and visual Go/NoGo tasks. Electroencephalography and Clinical Neurophysiology, 43, 864-875, which compared Go and NoGo topography after CNV was subtracted from NoGo trials only. Specifically, the NoGo P3 topography showed the distinctive frontocentral maximum, which is often linked to motor inhibition, when referenced to a pre-target baseline. This NoGo topography changed to a more parietal maximum, similar to that on Go trials, when referenced to a pre-cue baseline. Many researchers have cited this study, while failing to use the delayed response design on which Simson et al. based their argument. We attempted to replicate Simson et al.'s experiment with delayed responses and also with immediate responses, as are more often used. As expected, the amplitudes of CNV and P3 to both Go and NoGo trials were increased when immediate compared to delayed responses were required, but we failed to replicate the topographic shift of NoGo P3 with different baselines for both delayed and immediate responses. That is, subtraction of the CNV from NoGo P3 did not change the distinctive frontocentral topography of this component. The results suggest that CNV may affect the amplitude and measurement of the NoGo P3, but that NoGo P3 anteriorisation is not caused by CNV resolution.

Brain dynamics in the auditory oddball task as a function of stimulus intensity and task requirements.

We examined relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in an auditory oddball task, varying both stimulus intensity and active vs. passive task requirements between groups. We used a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). This study focused on the operation of three previously-reported phase-influenced mechanisms, involving prestimulus amplitudes, poststimulus amplitude changes, and the prestimulus contingent negative variation (CNV), in various EEG frequency bands. ERP responses to the standard stimuli were analysed. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz, and Pz. The occurrence of preferred phase-defined brain states was confirmed at a number of frequencies, crossing the traditional frequency bands. These preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and/or amplitude of all ERP components, and provided evidence of the operation of the three separate phase-influenced mechanisms. The preferred brain states occurred similarly across groups, suggesting that they reflect reflexive aspects of brain function associated with the timing of the stimuli, rather than voluntary attention. The impact on markers of cognitive function, such as the P3, suggests their important contributions to the efficiency of brain dynamics involved in perceptual and cognitive processing.

Movement-related potentials in the Go/NoGo task: the P3 reflects both cognitive and motor inhibition.

OBJECTIVE: The contribution of movement-related potentials (MRPs) to the Go/NoGo N2 and P3 'inhibitory' effects is controversial. This study examined these components in overt and covert response inhibition tasks. METHODS: Twenty adult participants counted or button-pressed in response to frequent (60%) and rare (20%) Go stimuli in a Go/NoGo task with equiprobable rare (20%) NoGo stimuli. RESULTS: The N2 NoGo effect did not differ between Count and Press responses, but the P3 NoGo effect was amplified during the Press task. Additionally, subtraction of the ERP waveform for Count NoGo from Press NoGo trials revealed a positivity between 200 and 400ms, occurring maximally over the central region, contralateral to the responding hand. This difference wave became significant at 210-260ms, close to the estimated time taken to stop an overt response. CONCLUSIONS: The N2 NoGo effect may reflect a non-motoric stage of inhibition, or recognition of the need for inhibition, while the NoGo P3 may overlap with a positive MRP occurring specifically on trials where overt motor responses must be inhibited. SIGNIFICANCE: The study confirms that the N2 and P3 NoGo effects are not solely due to movement-related potentials, and posits the NoGo P3 as a marker of motor inhibition.

Brain dynamics in the active vs. passive auditory oddball task: exploration of narrow-band EEG phase effects.

OBJECTIVE: We aimed to examine relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in active vs. passive auditory oddball tasks, using a novel conceptualisation of orthogonal phase effects. METHODS: This study focused on the operation of three recently-reported phase-influenced mechanisms, and ERP responses to the standard stimuli were analysed. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz and Pz. RESULTS: Preferred brain states at various frequencies were indicated by approximately 20% differential occurrence within the orthogonal phase dimensions explored. CONCLUSIONS: The preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and/or amplitude of various ERP components, and provided evidence for the operation of the three separate phase-influenced mechanisms. SIGNIFICANCE: Both the occurrence of preferred brain states, and the mechanisms linking them to ERP outcomes focused on here, appeared relatively invariant across tasks, suggesting that they largely reflect reflexive brain processes.

The development of stop-signal and Go/Nogo response inhibition in children aged 7-12 years: performance and event-related potential indices.

The present study examined the development of response inhibition during the Stop-signal and Go/Nogo tasks in children using performance and ERP measures. Twenty-four children aged 7 to 12 years completed both tasks, each with an auditory Nogo/Stop-signal presented on 30% of trials. On average, response inhibition was more difficult in the Stop-signal than Go/Nogo task. Response inhibition performance did not develop significantly across the age range, while response execution varied significantly in a task dependent manner (Go/Nogo: increasing accuracy and reducing response variability with age; Stop-signal: reducing Go mean reaction time and response variability with age). The N1, P2, N2 and P3 components showed different scalp distributions, with N1 and P2 peaking earlier, and P3 later, in Nogo compared to Stop stimuli. N2 and P3 amplitude were positively correlated with successful inhibition probability in the Go/Nogo task only. N2 amplitude and latency to both Nogo and successful Stop stimuli decreased linearly with age, but not in the frontal regions. N1 and P3 amplitude in the parietal region increased with age for Stop-signals. An age-related reduction in P3 latency to Nogo stimuli correlated significantly with reduced RT and variability in Go responding, indicating a relationship between efficient Nogo and Go processing. Together the behavioural and ERP results suggest little development of the response inhibition process as measured via the Stop-signal and Go/Nogo tasks across the 7 to 12 year age range, while response execution processes develop substantially.

Dynamics of narrow-band EEG phase effects in the passive auditory oddball task.

Evidence suggests that the component frequencies of the electroencephalogram (EEG) are dynamically adjusted to provide particular brain states at stimulus occurrence, and that these facilitate cortical processing of the stimulus. We examined relationships between stimulus intensity, the phase of narrow-band EEG activity at stimulus onset, and the resultant event-related potentials (ERPs) in a passive auditory oddball task, using a novel conceptualization of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). EEG responses to the standard stimuli (50 vs. 80 dB, varied between subjects) were analysed. Prestimulus narrow-band EEG activity (in 1-Hz bands from 1 to 13 Hz) at Cz was assessed for each trial by digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz and Pz. Preferred brain states at various frequencies were indicated by 16-34% differential occurrence within the orthogonal phase dimensions explored. The preferred states were associated with smaller N1, N2 and N3, larger P2 and P3, shorter N1, P2, N2 and P3 latencies, and some intensity effects. These effects reflected the operation of three separate phase-influenced mechanisms, involving anticipatory potentials and prestimulus/poststimulus amplitudes in various EEG frequencies. Results indicate that, even in paradigms with a slightly varying interstimulus interval, brain dynamics provide preferred brain states at the moment of stimulus presentation, which differentially affect the EEG correlates of stimulus processing.