Coherent oscillations in the theta-to-gamma frequency range have/nbeen proposed as a mechanism that/ncoordinates neural activity/nin large-scale cortical networks i/nn sensory, motor, and cognitive/ntasks. Whether this mechanism also involves coherent oscillations/nat delta frequencies (1/n–/n4 Hz) is not known. Rather, delta oscilla-/ntions have been associated with slow-wave sleep. Here, we show/ncoherent oscillations in the delta frequency band between parietal/nand frontal cortices during the decision-making component of a so-/nmatosensory discrimination task. Importantly, the magnitude of/nthis delta-band coherence is modulated by the different decision/nalternatives. Furthermore, during control conditions not requiring/ndecision making, delta-band coherences are typically much reduced./nOur work indicates an important role for synchronous activity in/nthe delta frequency band when large-scale, distant cortical net-/nworks coordinate their neural activity during decision making.

R.R./n’/ns research was partially supported by/nInternational Research Scholars Award 55005959 from the Howard Hughes/nMedical Institute, Dirección de Personal Académico de la Universidad Nacio-/nnal Autónoma de México Grant IN203210 and Consejo Nacional de Ciencia y/nTecnología Grant CB-2009-01-130863. V.N. was supported by a Ministerio de/nEducación y Ciencia (MEC)-Fullbright Postdoctoral Fellowship from the Span-/nish Ministry of Science and Technology and Dirección de Personal Académico/nde la Universidad Nacional Autónoma de México. A.L. was supported by the/nRamón y Cajal program from the Spanish government. G.D. was supported by/nthe European Research Council Advanced Grant DYSTRUCTURE 295129 and/nEuropean Union Seventh Framework Programme FP7/2007-2013 under Grant/n269921 (BrainScaleS).