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NoGo task: II. Fast wave effects
Symposia Abstracts / International Journal of Psychophysiology 85 (2012) 291–360
alpha. Again pre-stimulus alpha explained the most variance, followed by theta and delta. The present findings further support pre-stimulus EEG activity as an ERP determinant. Importantly, the pattern of pre-stimulus EEG/LPC relationships found here differs from that of our earlier Go/NoGo investigations. This suggests that the expression of the mechanisms underlying ERP genesis is sensitive to different paradigm manipulations.
355
Pre-stimulus EEG phase effects on children's ERPs R.J. Barry, F.M. De Blasio Centre for Psychophysics, Psychophysiology, and Psychopharmacology, University of Wollongong, Wollongong, Australia Brain & Behaviour Research Institute, University of Wollongong, Wollongong, Australia School of Psychology, University of Wollongong, Wollongong, Australia
doi:10.1016/j.ijpsycho.2012.06.172
Pre-stimulus EEG amplitude and ERPs in a Go/NoGo task: II. Fast wave effects F.M. De Blasio, R.J. Barry Centre for Psychophysics, Psychophysiology, and Psychopharmacology, University of Wollongong, Wollongong, Australia Brain & Behaviour Research Institute, University of Wollongong, Wollongong, Australia School of Psychology, University of Wollongong, Wollongong, Australia The pre-stimulus electroencephalographic (EEG) contributions in event-related potential (ERP) genesis have been much debated, and although the nature of these relationships has been investigated most in regard to the alpha band, opposing results have been reported (inverse vs. direct relationships). In an auditory context, investigations have typically been restricted to the assessment of peak-to-peak component amplitudes, and have generally focused on a single stimulus condition. Here we aim to clarify and extend the understanding of prestimulus alpha – ERP relationships by investigating each ERP component individually, for two stimulus conditions. Moreover, we expand our analysis to examine the pre-stimulus EEG–ERP contributions in the beta band, as we cannot find evidence of prior investigations of this nature involving beta. This was the second of a two part investigation (N= 20) employing an equiprobable auditory Go/NoGo paradigm with button press response. The pre-stimulus (−500 to 0 ms) epochs at Cz were subjected to Fast Fourier Transform, and the mean activity in the alpha (8–13 Hz) and beta (14–24 Hz) bands were separately derived. The ascending order of pre-stimulus band activity at the vertex was then applied to the pre–post stimulus epochs (±500 ms) at nine sites (F3, Fz, F4, C3, Cz, C4, P3, Pz, and P4), from which the High (top third) and Low (bottom third) pre-stimulus EEG level ERPs were generated. In addition to the ERP amplitudes and latencies of five components (P1, N1, P2, N2, and P3), Go RTs were also assessed. Pre-stimulus alpha level had no significant effect on ERP component latencies, although alpha did produce amplitude effects in P1, P2 and P3: High pre-stimulus alpha was associated with right hemispheric enhancements, parietally in P1, and centrally in P2, and was associated with increased P3. There were no stimulus interactions, nor RT effects in alpha. In beta, High pre-stimulus activity was associated with a reduction in Go N1 latency, and also with main, topographical, and stimulus interactions, each resulting in increased P1 amplitudes. In contrast, Low pre-stimulus beta was associated with amplitude enhancements in N1 centrally, and in P2 at the vertex. RT showed no effect of pre-stimulus beta. Pre-stimulus alpha activity directly modulated the amplitudes of the positive components. This finding both confirms recent reports, and clarifies the previously found peak-to-peak findings as having been driven by effects in the positive components. Pre-stimulus cortical activation, as indexed by beta band activity, directly modulated Go N1 latency, and P1 amplitude, but inversely modulated both N1 and P2 amplitudes. These findings suggest that pre-stimulus beta is an important determinant of sensoryprocessing related outcomes. doi:10.1016/j.ijpsycho.2012.06.173
Using a child sample aged 8–12 years (N= 24), we examined effects of the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset on the resultant event-related potentials (ERPs) in an equiprobable auditory Go/NoGo task with a fixed stimulus-onset asynchrony. ERP responses were analysed in the context of a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, and waxing vs. waning). We used FFT decomposition of the EEG at Cz to assess prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) for each trial. Using the cycle at stimulus onset, trials were sorted into four phases for each of the 13 frequencies. RTs, and pre- and post-stimulus RMS amplitudes and ERPs from the raw EEG activity at the midline sites, were derived for each of these. In the ERPs, the amplitude of prestimulus CNVlike changes, and amplitudes and latencies of N1 and P3 were extracted. These measures were examined as a function of narrow-band EEG phase. At a number of frequencies, crossing the traditional broad frequency bands, the predicted non-random occurrence of phasedefined brain states was confirmed — preferred phases occurred some 13–38% more often than the non-preferred phases. The likelihood of this occurring by chance was ~1 in 25 billion. Significant effects of phase were found in RT, prestimulus RMS amplitudes, changes in RMS at stimulus onset, the CNV-like prestimulus slow potential change, and in N1 and P3 amplitudes and latencies. Some of the latter effects differed between Go and NoGo conditions. The preferred phase states were associated with more efficient processing of the stimuli, as reflected in differences in latency and amplitude of the N1 and P3 ERP components. The present results confirm the existence of preferred brain states and their impact on the efficiency of brain dynamics involved in perceptual and cognitive processing. Importantly, these effects were derived from a different age group than the adults assessed previously. Children have both different resting EEG profiles (amplitudes and topography) and ERP responses compared with adults in this paradigm. Although the preferred phase results are somewhat weaker than those previously found in adults, they serve to indicate the robust nature of this phenomenon. Further work on this phenomenon may contribute to our understanding of phase dynamics in the genesis of the ERP.
doi:10.1016/j.ijpsycho.2012.06.174
Symposium D: Sleep and cortical dynamics in normal and pathological conditions Symposium Chair: Angelo Gemignani (Italy) This symposium examines the cortical activity during sleep and scrutinizes pivotal methodological issues of key importance for the clinical research field. Indeed this symposium looks at the interaction between the sleeping brain and the environment as well as at the relationships between physiological and clinical events. Researchers from four laboratories show new vistas in physiological and pathological responses related to normal sleepers and insomniacs. The applied methodologies include Neuroimaging, High Density EEG and deep stereotaxic EEG. Laurino et al. and Oniz et al. present two researches aimed at identifying cortical responses to sensory stimulation during sleep. Nobili, using intracerebral EEG, identifies the coexistence of wake-
alpha. Again pre-stimulus alpha explained the most variance, followed by theta and delta. The present findings further support pre-stimulus EEG activity as an ERP determinant. Importantly, the pattern of pre-stimulus EEG/LPC relationships found here differs from that of our earlier Go/NoGo investigations. This suggests that the expression of the mechanisms underlying ERP genesis is sensitive to different paradigm manipulations.
355
Pre-stimulus EEG phase effects on children's ERPs R.J. Barry, F.M. De Blasio Centre for Psychophysics, Psychophysiology, and Psychopharmacology, University of Wollongong, Wollongong, Australia Brain & Behaviour Research Institute, University of Wollongong, Wollongong, Australia School of Psychology, University of Wollongong, Wollongong, Australia
doi:10.1016/j.ijpsycho.2012.06.172
Pre-stimulus EEG amplitude and ERPs in a Go/NoGo task: II. Fast wave effects F.M. De Blasio, R.J. Barry Centre for Psychophysics, Psychophysiology, and Psychopharmacology, University of Wollongong, Wollongong, Australia Brain & Behaviour Research Institute, University of Wollongong, Wollongong, Australia School of Psychology, University of Wollongong, Wollongong, Australia The pre-stimulus electroencephalographic (EEG) contributions in event-related potential (ERP) genesis have been much debated, and although the nature of these relationships has been investigated most in regard to the alpha band, opposing results have been reported (inverse vs. direct relationships). In an auditory context, investigations have typically been restricted to the assessment of peak-to-peak component amplitudes, and have generally focused on a single stimulus condition. Here we aim to clarify and extend the understanding of prestimulus alpha – ERP relationships by investigating each ERP component individually, for two stimulus conditions. Moreover, we expand our analysis to examine the pre-stimulus EEG–ERP contributions in the beta band, as we cannot find evidence of prior investigations of this nature involving beta. This was the second of a two part investigation (N= 20) employing an equiprobable auditory Go/NoGo paradigm with button press response. The pre-stimulus (−500 to 0 ms) epochs at Cz were subjected to Fast Fourier Transform, and the mean activity in the alpha (8–13 Hz) and beta (14–24 Hz) bands were separately derived. The ascending order of pre-stimulus band activity at the vertex was then applied to the pre–post stimulus epochs (±500 ms) at nine sites (F3, Fz, F4, C3, Cz, C4, P3, Pz, and P4), from which the High (top third) and Low (bottom third) pre-stimulus EEG level ERPs were generated. In addition to the ERP amplitudes and latencies of five components (P1, N1, P2, N2, and P3), Go RTs were also assessed. Pre-stimulus alpha level had no significant effect on ERP component latencies, although alpha did produce amplitude effects in P1, P2 and P3: High pre-stimulus alpha was associated with right hemispheric enhancements, parietally in P1, and centrally in P2, and was associated with increased P3. There were no stimulus interactions, nor RT effects in alpha. In beta, High pre-stimulus activity was associated with a reduction in Go N1 latency, and also with main, topographical, and stimulus interactions, each resulting in increased P1 amplitudes. In contrast, Low pre-stimulus beta was associated with amplitude enhancements in N1 centrally, and in P2 at the vertex. RT showed no effect of pre-stimulus beta. Pre-stimulus alpha activity directly modulated the amplitudes of the positive components. This finding both confirms recent reports, and clarifies the previously found peak-to-peak findings as having been driven by effects in the positive components. Pre-stimulus cortical activation, as indexed by beta band activity, directly modulated Go N1 latency, and P1 amplitude, but inversely modulated both N1 and P2 amplitudes. These findings suggest that pre-stimulus beta is an important determinant of sensoryprocessing related outcomes. doi:10.1016/j.ijpsycho.2012.06.173
Using a child sample aged 8–12 years (N= 24), we examined effects of the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset on the resultant event-related potentials (ERPs) in an equiprobable auditory Go/NoGo task with a fixed stimulus-onset asynchrony. ERP responses were analysed in the context of a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, and waxing vs. waning). We used FFT decomposition of the EEG at Cz to assess prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) for each trial. Using the cycle at stimulus onset, trials were sorted into four phases for each of the 13 frequencies. RTs, and pre- and post-stimulus RMS amplitudes and ERPs from the raw EEG activity at the midline sites, were derived for each of these. In the ERPs, the amplitude of prestimulus CNVlike changes, and amplitudes and latencies of N1 and P3 were extracted. These measures were examined as a function of narrow-band EEG phase. At a number of frequencies, crossing the traditional broad frequency bands, the predicted non-random occurrence of phasedefined brain states was confirmed — preferred phases occurred some 13–38% more often than the non-preferred phases. The likelihood of this occurring by chance was ~1 in 25 billion. Significant effects of phase were found in RT, prestimulus RMS amplitudes, changes in RMS at stimulus onset, the CNV-like prestimulus slow potential change, and in N1 and P3 amplitudes and latencies. Some of the latter effects differed between Go and NoGo conditions. The preferred phase states were associated with more efficient processing of the stimuli, as reflected in differences in latency and amplitude of the N1 and P3 ERP components. The present results confirm the existence of preferred brain states and their impact on the efficiency of brain dynamics involved in perceptual and cognitive processing. Importantly, these effects were derived from a different age group than the adults assessed previously. Children have both different resting EEG profiles (amplitudes and topography) and ERP responses compared with adults in this paradigm. Although the preferred phase results are somewhat weaker than those previously found in adults, they serve to indicate the robust nature of this phenomenon. Further work on this phenomenon may contribute to our understanding of phase dynamics in the genesis of the ERP.
doi:10.1016/j.ijpsycho.2012.06.174
Symposium D: Sleep and cortical dynamics in normal and pathological conditions Symposium Chair: Angelo Gemignani (Italy) This symposium examines the cortical activity during sleep and scrutinizes pivotal methodological issues of key importance for the clinical research field. Indeed this symposium looks at the interaction between the sleeping brain and the environment as well as at the relationships between physiological and clinical events. Researchers from four laboratories show new vistas in physiological and pathological responses related to normal sleepers and insomniacs. The applied methodologies include Neuroimaging, High Density EEG and deep stereotaxic EEG. Laurino et al. and Oniz et al. present two researches aimed at identifying cortical responses to sensory stimulation during sleep. Nobili, using intracerebral EEG, identifies the coexistence of wake-