State-dependent studies on perception and cognition

Neuronal response to an external stimulus is affected not only by stimulus properties, but also by the baseline activation state; this is referred to as state-dependency. Leveraging this principle helps to enhance the specificity and reduce the variability of brain stimulation effects. State-dependent paradigms have proven to be successful in enhancing the functional resolution of brain stimulation to the extent that the tuning of neuronal representations can be revealed, and they have also enhanced clinical benefits in the treatment of disorders such as depression. Furthermore, state-dependent approach has been applied in various brain stimulation protocols, including online and offline transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), and paired-pulse associative stimulation. This chapter describes the principles and mechanisms of state-dependent brain stimulation and summarizes its contribution to cognitive neuroscience.