Network-Matched Transcranial Direct Current Stimulation During Focused-Attention and Open-Monitoring Meditation: Protocol for a Nine-Arm Factorial Test of Network Specificity

Abstract

Background. Combining mindfulness training with transcranial direct current stimulation (tDCS) is feasible and generally well tolerated, but the existing literature has produced feasibility findings rather than mechanistic ones. No trial has contrasted a stimulation montage matched to the network a contemplative practice preferentially engages against a montage matched to a different practice's network. As a result, it is unknown whether any observed benefit reflects network-specific pairing or a generic effect of stimulation on attention and mood. Objectives. To specify, in advance and in public, a design capable of discriminating network specificity from generic augmentation; to define the estimands for the primary and secondary tests; and to prespecify the outcomes that would falsify the hypothesis. Design. A nine-arm parallel-group factorial trial. Six cells cross practice family (focused attention, open monitoring) with stimulation condition (anodal F3, anodal F8, sham). Three further no-practice cells (F3 alone, F8 alone, passive control) supply the single-component conditions required to evaluate superadditivity as a measured rather than inferred quantity. A loving-kindness arm is deliberately excluded and deferred. Endpoints. The primary endpoint is the practice-by-montage interaction on a single common outcome measured identically in all nine cells, not a main effect of stimulation. Prespecified secondary tests are a superadditivity contrast referenced to the passive-control baseline and a practice-by-montage-by-marker interaction. Individualized current-flow modelling is performed before randomization and entered as a prespecified moderator. Falsification. The framework makes one primary claim and two mechanistic subclaims that fail separately. Absence of an adequately powered practice-by-montage interaction requires the hypothesis to be abandoned rather than qualified. Failure of timing to moderate the interaction would weaken the state-dependent-plasticity account without refuting network matching. Failure of the predicted neural markers to move would refute the proposed target-engagement mechanism. Status and dissemination. Design protocol only; not funded, not approved, not registered. Results will be reported regardless of direction, and null findings on the same terms as positive ones.