The brain varies its state in accordance with the internal and external context, resulting into distinct patterns of activity and dynamics. The cerebral cortex and the interactions between cortical and subcortical areas, have a major role in the establishment and switching between different brain states. In the present Thesis research work, we used multiple local field potentials, calcium imaging recordings and thalamic stimulation to explore different cortical dynamics at distinct brain states. First, we investigated the physiological sleep-wake rhythms and spontaneous brain transitions. Secondly, we explored the transitions taking place over different levels of anesthesia, characterizing from a multiscale perspective, the cortical dynamics when transitioning from deep anesthesia to wakefulness. Finally, we investigated the impact of thalamic stimulation on the induction of brain transitions and found that it induces a transition from deep anesthesia to that equivalent to a higher arousal, a strategy that has been investigated for its clinical potential.