Do people have a different shade of consciousness when improvising jazz? I picture a jazz musician standing with his eyes closed, in a sort of trance, completely lost from the world, flowing zen-like with the spontaneous music, expressing his own sense of beauty in the thread he weaves into the fabric of the group. Limb and Braun (see citation) have published a paper on the changes in brain activity during improvisation.
Their description of this state:
It has also been suggested that deactivation of the lateral prefrontal regions represents the primary physiologic change responsible for altered states of consciousness such as hypnosis, meditation or even daydreaming. This is interesting in that jazz improvisation, as well as many other types of creative activity, have been proposed to take place in an analogously altered state of mind. Moreover, a comparable dissociated pattern of activity in prefrontal regions has been reported to occur during REM sleep , a provocative finding when one considers that dreaming is exemplified by a sense of defocused attention, an abundance of unplanned, irrational associations and apparent loss of volitional control, features that may be associated with creative activity during wakefulness as well.
But the jazz improvisation is not without structure it follows rules, some general to the genre and some deeply personal. The music is new and fresh but not outside some limits or random or meaningless.
What happens in the brain? Limb and Braun did fMRI scans on 6 experienced right-handed jazz pianists while they rested and while they played a scale, improvised on that scale, played a practiced piece with a jazz group backing through headphones, and improvised to the same backing. Recordings were also taken from the keyboard midi output to check on the details of the playing. There was high correspondence between the subjects and between the simple and complex improvising.
There was a change in the prefrontal cortex activity. The activity of the front middle was increased and the back and sides were decreased. The middle of the prefrontal cortex is in general associated with an autobiographical narrative. It has a role in the neural instantiation of self, organizing internally motivated, self-generated, and stimulus-independent behaviors. The portion of the front of this area (frontal polar cortex) is very selectively activated during improvisation. It is poorly understood but appears to serve a broad-based integrative function, combining multiple cognitive operations in the pursuit of higher behavioral goals, in particular adopting and utilizing rule sets that guide ongoing behavior and maintaining an overriding set of intentions while executing a series of diverse behavioral subroutines. All of these functions are necessarily required during the task of improvisation.
In other activities it has been found that attention and conscious self-monitoring can inhibit performance as well as spontaneity. The areas that were deactivated:
are thought to provide a cognitive framework within which goal-directed behaviors are consciously monitored, evaluated and corrected. The LOFC (lateral orbitofrontal cortex) may be involved in assessing whether such behaviors conform to social demands, exerting inhibitory control over inappropriate or maladaptive performance. The DLPFC (dorsolateral prefrontal cortex), on the other hand, is thought to be responsible for planning, stepwise implementation and on-line adjustment of behavioral sequences that require retention of preceding steps in working memory.
There was increased activity in the sensorimotor areas. This is probably because of the extra effort require to plan and implement new (not practiced or remembered) motor patterns and heighten sensory perception. At the same time there was decreased activity in some limbic areas. Music in general affects the limbic area both increasing and decreasing activity in various parts. This is not surprising given the link between music and emotion. The authors do not mention the idea of a suppression of memory and habit being a possible explanation although I think that it would contribute.
Here is their abstract:
To investigate the neural substrates that underlie spontaneous musical performance, we examined improvisation in professional jazz pianists using functional MRI. By employing two paradigms that differed widely in musical complexity, we found that improvisation (compared to production of over-learned musical sequences) was consistently characterized by a dissociated pattern of activity in the prefrontal cortex: extensive deactivation of dorsolateral prefrontal and lateral orbital regions with focal activation of the medial prefrontal (frontal polar) cortex. Such a pattern may reflect a combination of psychological processes required for spontaneous improvisation, in which internally motivated, stimulus-independent behaviors unfold in the absence of central processes that typically mediate self-monitoring and conscious volitional control of ongoing performance. Changes in prefrontal activity during improvisation were accompanied by widespread activation of neocortical sensorimotor areas (that mediate the organization and execution of musical performance) as well as deactivation of limbic structures (that regulate motivation and emotional tone). This distributed neural pattern may provide a cognitive context that enables the emergence of spontaneous creative activity.
Limb, C., & Braun, A. (2008). Neural Substrates of Spontaneous Musical Performance: An fMRI Study of Jazz Improvisation PLoS ONE, 3 (2) DOI: 10.1371/journal.pone.0001679