Event-related delta, theta, alpha and gamma correlates to auditory oddball processing during Vipassana meditation

"Standard stimuli also evinced significantly greater theta inter-trial coherence during meditation compared with control state."

Standard stimulus-related processing, p. 104

Enhanced theta phase-locking to repeated standards during meditation indicates stronger temporal coordination of sensory processing, a candidate mechanism for binding/segmentation in conscious access .

"For the theta phase synchrony (100–400 ms) measure to standards, a significant state effect was obtained... the passive control state was associated with significantly less theta synchrony to standards compared with active task activity (P < 0.005), but the passive meditation state was not significantly different from active task theta synchrony (P = 0.42)."

Meditation state and active task activity, p. 106

Theta synchrony during meditation matched active-task levels, suggesting meditation recruits timing mechanisms that support conscious processing without overt task demands .

"Data reflecting event-related spectral perturbation and inter-trial coherence (phase locking) were derived from delta (2–4 Hz), theta (4–8 Hz), alpha-1 (8–10 Hz) and alpha-2 (10–12 Hz)... The inter-trial coherence and spectral power calculations were obtained using the complex Gaussian wavelet."

Methods, p. 102

Inter-trial coherence provides a quantitative measure of temporal coordination (phase-locking) across trials, operationalizing oscillatory timing mechanisms relevant to conscious processing .

Figures

Fig. 3 (p. 106) : Shows enhanced theta phase-locking, including during meditation, linking oscillatory timing to altered processing states relevant for conscious access .

"The present findings describe further the neuroelectric brain state produced by this meditation practice... and the results imply that such practice involves enhancement in early stimulus-representation... Also found was decreased frontal responsivity to distracting stimuli accompanied by a dissociation between the normal positive relationship between early enhanced P3/evoked delta and later event-related desynchronization of alpha power."

DISCUSSION, p. 107

Authors interpret decreased frontal/delta responses with increased later alpha ERD to distracters as altered top-down gating, consistent with selective routing mechanisms for attentional control in conscious processing .

"For the late 500–900 ms alpha-1 power from distracter processing, a state effect was obtained... active task late alpha-1 power decreases to distracter stimuli were significantly greater than the control state (P < 0.05) but indistinguishable from the meditation state (P = 0.97)."

Meditation state and active task activity, p. 107

Late alpha ERD to distracters in meditation mirrors active-task engagement, indicating selective routing that maintains processing while reducing early frontal reactivity .

"The attention-related recruitment of 2–4 Hz power to distracters was decreased in meditation... This was complemented by the late event-related alpha desynchronization to the distracters that was actually increased in meditation."

CONCLUSIONS, p. 109

Summary emphasizes reduced early delta with increased late alpha ERD for distracters during meditation, a pattern indicative of altered gating/selection in the processing pipeline .

Figures

Fig. 5 (p. 107) : Demonstrates larger late alpha desynchronization to distracters in meditation/active vs control, consistent with later-stage selective processing .

Fig. 2 (p. 104) : Visualizes early delta dynamics to distracters across states, supporting claims about reduced early frontal delta recruitment during meditation .

"The statistical analysis of the 35–45 Hz phase synchrony data across stimulus types yielded significant outcomes for both control [F(2,30)=24.0, P < 0.00001] and meditation [F(2,30)=25.5, P < 0.00001] states... The 35–45 Hz post-stimulus power across stimulus types was not significant for control... but it was significant for meditation state [F(2,30)=5.3, P < 0.01]."

Standard stimulus-related processing / Individual differences, p. 105

Significant gamma-band phase synchrony and state-dependent power modulation during meditation point to enhanced integration by synchrony mechanisms linked to conscious representation .

"For the longer term practitioners, meditation state yielded higher gamma phase synchrony values during meditation at frontal (P < 0.05), but not central or parietal sites (P > 0.97, all comparisons)."

Individual differences, p. 105

Expertise-dependent increases in gamma synchrony during meditation suggest strengthened large-scale binding/integration, a proposed substrate for unified conscious contents .

Figures

Fig. 6 (p. 107) : Displays gamma synchrony and power patterns across states and stimuli; meditation emphasizes stimulus-differential gamma, consistent with integrative binding by synchrony .