Erol Başar and the scientific revolution in nonlinear brain dynamics: A selective review

Erol Başar was one of the most significant neuroscientists of the past century. Two main threads of thought guided Başar's scientific labor: i) the study of brain oscillations and ii) its marriage to basic principles of physics. These two threads provided him with the crucial element to introduce nonlinear random theory into brain research. Until the decade of the seventies, the underling paradigm in studying the electrical activity of the brain was dominated by a simplistic linear systems model that entailed absolute separation between a determinist evoked responses to stimuli and a superimposed background electrical activity considered as "noise". Başar questioned this simplistic linear model and its interpretation. Başar underscored the nonlinear dynamics of the brain, demonstrated for the first time the interaction between evoked and background activity, and widened the study of event-related activity from the time domain to the frequency and time-frequency domain, heralding a new understanding of the event-related dynamics. These advances were a consequence of Başar's fascination with the physics and mathematics of dynamical physical systems which he rightly believed to be the key to understanding the brain. Here we carry out a selected review, based on a scientometric analysis of Başar's scientific trajectory in the field of Brain Dynamics as embodied in 278 peer-reviewed papers. We also report the geographical distribution of Başar's collaborators, distribution of his citations, and his interaction with many international groups. This analysis illustrates the importance of his innovative contributions and the impact it had on our field. It underscores that he is one of the initiators of a "scientific revolution" in neurophysiology: from linear systems to random non-linear systems analysis and the new vision of the brain as a dynamical system.