Morten L Kringelbach writes:

The execution of any musical symphony is a difficult task, demanding significant skills from each musician. Perhaps the hardest task lies with the conductor who must orchestrate the musicians so the music comes alive cohesively and speaks to our deepest emotions. The human brain is like an orchestra: different regions perform different types of processing, much like the individual musicians who must read the music, play their instruments, and also listen and adapt to the sounds others make. Yet the conductor’s role is different from anything that occurs in the brain. Without a conductor, the music almost always fails – as the filmmaker Federico Fellini showed in Prova d’orchestra (1978), or Orchestra Rehearsal.

Do such musical metaphors give us any insights into actual brain functioning? Since the beginning of neuroscience as its own discipline in the early 20th century, there have been many theories about how the brain works. One of the most heated discussions was between two Nobel Prize-winners – Santiago Ramón y Cajal and Camillo Golgi – over the role of local versus global coding and processing in the brain. Ramón y Cajal was arguing for a localist perspective where the single neurons carried out most if not all of the coding, while Golgi was in favour of global, distributed processing. Initially, Ramón y Cajal seemed victorious, mostly due to his careful dissection and beautiful drawings of neurons and their synapses. This strongly biased neurophysiology research, leading to remarkable single-neuron recordings, such as those in the Nobel Prize-winning work on the visual system by David Hubel and Torsten Wiesel.

Over the past few decades, human neuroimaging has taken this localist approach to an even higher level with correlations of often indirect measures of brain activity with behaviour, establishing a highly successful and highly cited field. Yet, in contrast to this localist legacy, recent work has started to take inspiration from the dynamical systems described by physics and mathematics, such as the one put forward by the physicist Hermann Haken, and has shown how the meso- and macroscopic distributed activity of these models adds synergistically to the microscopic (localist) activity.

This new framework points to a view of the brain as a fusion of the local and the global, arranged in a hierarchical manner. [Continue reading…]