Mapping of early and late human somatosensory evoked brain potentials to phasic galvanic painful stimulation

Miniussi

Cognitive Brain Research

et al. 2004

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122

In the present high-resolution electroencephalographic (EEG) study, event-related desynchronization/synchronization (ERD/ERS) of alpha rhythms was computed during an S1 -S2 paradigm, in which a visual cue (S1) predicted a SHORT (600 ms) or LONG (1400 ms) foreperiod, preceding a visual go stimulus (S2) triggering right or left finger movement. Could orienting attention to a selective point in time influence the alpha rhythms as a function of the SHORT vs. LONG foreperiod? Stronger selective attentional modulations were predicted for the SHORT than LONG condition. EEG data from 54 channels were ''depurated'' from phase-locked visual evoked potentials and spatially enhanced by surface Laplacian estimation (i.e., final data analysis was conducted on 16 subjects having a sufficient number of artifact-free EEG single trials). Low-band alpha rhythms (about 6 -10 Hz) were supposed to be related to anticipatory attentional processes, whereas high-band alpha rhythms (10 -12 Hz) would indicate task-specific visuo-motor processes.Compared to the LONG condition (foreperiod), the SHORT condition induced a quicker and stronger ERS at low-band alpha rhythm (about 6 -8 Hz) over midline and bilateral prefrontal, sensorimotor, and posterior parietal areas. In contrast, the concomitant high-band alpha (about 10 -12 Hz) ERD/ERS showed no significant difference between the two conditions. In conclusion, temporal attention for a sub-second delay (800 ms) did modulate low-band alpha rhythm over large regions of both cortical hemispheres. D 2004 Elsevier B.V. All rights reserved.Theme: Neural basis of behavior Topic: Cognition

Section: Methodological Remarksmentioning

confidence: 99%

Sub-second “temporal attention” modulates alpha rhythms. A high-resolution EEG study

Miniussi

Cognitive Brain Research

et al. 2004

Self Cite

122

“…As an advantage, the mapping procedure required no computational assumption such as the number of equivalent dipoles or the regularization parameters of the linear inverse estimation (Babiloni et al, 2001a). In previous studies, the mapping of the ERD/ERS has provided very interesting findings on brain rhythms accompanying somatosensory, motor and cognitive demands (Babiloni et al, 1999(Babiloni et al, , 2000(Babiloni et al, , 2001b(Babiloni et al, , 2002Gevins and Smith, 2000;Gevins et al, 1998;McEvoy et al, 2001;Okada and Salenius, 1998). As a limitation, the cortical sources of the ERD/ERS must be inferred with caution based on the topographical mapping.…”

Section: Methodological Remarksmentioning

confidence: 99%

Human cortical EEG rhythms during long-term episodic memory task. A high-resolution EEG study of the HERA model

Carducci

et al. 2004

NeuroImage

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Many recent neuroimaging studies of episodic memory have indicated an asymmetry in prefrontal involvement, with the left prefrontal cortex more involved than the right in encoding, the right more than the left in retrieval (hemispheric encoding and retrieval asymmetry, or HERA model). In this electroencephalographic (EEG) high-resolution study, we studied brain rhythmicity during a visual episodic memory (recognition) task. The theta (4-6 Hz), alpha (6-12 Hz) and gamma (28-48 Hz) oscillations were investigated during a visuospatial long-term episodic memory task including an encoding (ENC) and retrieval (RET) phases. During the ENC phase, 25 figures representing interiors of buildings ("indoor") were randomly intermingled with 25 figures representing landscapes ("landscapes"). Subject's response was given at left ("indoor") or right ("landscapes") mouse button. During the RET phase (1 h later), 25 figures representing previously presented "indoor" pictures ("tests") were randomly intermingled with 25 figures representing novel "indoor" ("distractors"). Again, a mouse response was required. Theta and alpha EEG results showed no change of frontal rhythmicity. In contrast, the HERA prediction of asymmetry was fitted only by EEG gamma responses, but only in the posterior parietal areas. The ENC phase was associated with gamma EEG oscillations over left parietal cortex. Afterward, the RET phase was associated with gamma EEG oscillations predominantly over right parietal cortex. The predicted HERA asymmetry was thus observed in an unexpected location. This discrepancy may be due to the differential sensitivity of neuroimaging methods to selected components of cognitive processing. The strict relation between gamma response and perception suggests that retrieval processes of long-term memory deeply impinged upon sensory representation of the stored material. © 2004 Elsevier Inc. All rights reserved

“…In this work, cortical activity from EEG scalp recordings was estimated by employing the high-resolution EEG technologies He et al 1999;Nunez 1995;Babiloni et al 2001;De Vico Fallani et al 2007) with the use of a realistic head model known as average head model from Mc Gill University. The scalp, skull and dura mater compartments were build by using 1200 triangles for each structures, and the Boundary Element Model was then employed to solve the forward electromagnetic model.…”

Section: Estimation Of Cortical Activitymentioning

confidence: 99%

Changes in Brain Activity During the Observation of TV Commercials by Using EEG, GSR and HR Measurements

et al. 2009

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In this study we were interested to analyse the brain activity occurring during the "naturalistic" observation of commercial ads intermingled in a random order within a documentary. In order to measure both the brain activity and the emotional engage of the 15 healthy subjects investigated, we used simultaneous EEG, Galvanic Skin Response (GSR), Heart Rate (HR) recordings during the whole experiment. We would like to link significant variation of EEG, GSR, HR and Heart Rate Variability (HRV) measurements with the memory and pleasantness of the stimuli presented, as resulted successively from the subject's verbal interview. In order to do that, different indexes were employed to summarize the cerebral and autonomic measurements performed. Such indexes were used in the statistical analysis, performed with the use of Analysis of Variance (ANOVA) and z-score transformation of the estimated cortical activity by solving the associated EEG inverse problem. The results are summarized as follows: (1) in the population analyzed, the cortical activity in the theta band elicited during the observation of the TV commercials that were remembered is higher and localized in the left frontal brain areas when compared to the activity elicited during the vision of the TV commercials that were forgotten (p< 0.048). Same increase in the theta activity occurred during the observation of commercials that were judgment pleasant when compared with the other (p < 0.042). Differences in cortical activity were also observed for the gamma activity, bilaterally in frontal and prefrontal areas. (2) the HR and HRV activity elicited during the observation of the TV commercials that were remembered or judged pleasant is higher than the same activity during the observation of commercials that will be forgotten (p < 0.001 and p < 0.048, respectively for HR and HRV) or were judged unpleasant (p < 0.042 and p < 0.04, respectively for HR and HRV). No statistical differences between the level of the GSR values were observed across the experimental conditions. In conclusion, the TV commercials proposed to the population analyzed have increased the HR values and the cerebral activity mainly in the theta band in the left hemisphere when they will be memorized and judged pleasant. Further research with an extended set of subjects will be necessary to further validate the observations reported in this paper. However, these conclusions seems reasonable and well inserted in the already existing literature on this topic related to the HERA model.