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Seats of self-awareness in brain revealed anew—through sleep, researchers say

July 30, 2012
Courtesy of the Max Planck Institutes of Psychiatry
and World Science staff

Sci­en­tists have tak­en a new tack to find­ing out which parts of our brain han­dle self-aware­ness. They have scanned the brains of peo­ple who are dream­ing while be­ing aware that they’re dream­ing.

“In a nor­mal dream… we ex­pe­ri­ence per­cep­tions and emo­tions but we are not aware that we are only dream­ing. It’s only in a lu­cid dream that the dream­er gets a meta-in­sight,” or in­sight in­to his or her own awareness, said Mar­tin Dresler of the Max Planck In­sti­tutes of Psy­chi­a­try in Mu­nich, who worked on the stu­dy.

The find­ings are pub­lished in the re­search jour­nal Sleep.

Brain re­gions ac­ti­vat­ed more strongly dur­ing lu­cid dream­ing than in a nor­mal dream. (© MPI of Psy­chi­a­try)
Not every­one is able to dream lu­cid­ly, though the abil­ity can be de­vel­oped. The re­search, us­ing a type of brain scan known as mag­net­ic res­o­nance to­mog­ra­phy, found that a spe­cif­ic net­work of brain ar­eas is ac­ti­vat­ed dur­ing lu­cid dream­ing. The net­work con­sists of re­gions al­ready known to be as­so­ci­at­ed with self-re­flec­tive func­tions while wak­ing. They are called the right dor­so­lat­er­al pre­fron­tal cor­tex, the fron­topo­lar re­gions and the pre­cuneus. 

The hu­man ca­pa­city of self-per­cep­tion, self-re­flec­tion and con­scious­ness de­vel­op­ment are among the un­solved mys­ter­ies of neu­ro­sci­ence. De­spite mod­ern im­ag­ing tech­niques, it’s still im­pos­si­ble to fully vis­u­al­ise what goes on in the brain when peo­ple move to con­scious­ness from an un­con­scious state, re­search­ers say. 

The prob­lem lies in the fact that it is dif­fi­cult to watch our brain dur­ing this tran­si­tion­al change. Al­though this pro­cess is the same, eve­ry time a per­son awak­ens from sleep, the bas­ic ac­ti­vity of our brain is usu­ally greatly re­duced dur­ing deep sleep. This makes it hard to tell apart the brain ac­ti­vity un­der­ly­ing the re­gained self-per­cep­tion and con­scious­ness, from the wid­er changes in brain ac­ti­vity that oc­cur at the same time.

By com­par­ing the ac­ti­vity of the brain dur­ing one of these lu­cid pe­ri­ods with the ac­ti­vity meas­ured im­me­di­ately be­fore in a nor­mal dream, the sci­en­tists hoped to iden­ti­fy some char­ac­ter­is­tic brain ac­ti­vi­ties of awareness.

“The gen­er­al bas­ic ac­ti­vity of the brain is si­m­i­lar in a nor­mal dream and in a lu­cid dream,” said Mi­chael Czisch, head of a re­search group at the Max Planck In­sti­tutes. “In a lu­cid state, how­ev­er, the ac­ti­vity in cer­tain ar­eas of the cer­e­bral cor­tex,” the more ad­vanced part of the brain, “in­creases markedly with­in sec­onds. The in­volved ar­eas of the cer­e­bral cor­tex are the right dor­so­lat­er­al pre­fron­tal cor­tex, to which com­monly the func­tion of self-assessment is at­trib­ut­ed, and the fron­topo­lar re­gions, which are re­spon­si­ble for eval­u­at­ing our own thoughts and feel­ings. The pre­cun­eus is al­so es­pe­cially ac­tive, a part of the brain that has long been linked with self-per­cep­tion.”

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Scientists have taken a new tack to finding out which parts of our brain handle self-awareness. They have scanned the brains of people who are dreaming while being aware that they’re dreaming. “In a normal dream… we experience perceptions and emotions but we are not aware that we are only dreaming. It’s only in a lucid dream that the dreamer gets a meta-insight,” or insight into his or her own awareness, said Martin Dresler of the Max Planck Institutes of Psychiatry in Munich, who worked on the study. The findings are published in the research journal Sleep. The research, using a type of brain scan known as magnetic resonance tomography, found that a specific network of brain areas is activated during lucid dreaming. The network consists of regions already known to be associated with self-reflective functions while waking. They are called the right dorsolateral prefrontal cortex, the frontopolar regions and the precuneus. The human capacity of self-perception, self-reflection and consciousness development are among the unsolved mysteries of neuroscience. Despite modern imaging techniques, it’s still impossible to fully visualise what goes on in the brain when people move to consciousness from an unconscious state, researchers say. The problem lies in the fact that it is difficult to watch our brain during this transitional change. Although this process is the same, every time a person awakens from sleep, the basic activity of our brain is usually greatly reduced during deep sleep. This makes it hard to tell apart the brain activity underlying the regained self-perception and consciousness, from the wider changes in brain activity that occur at the same time. By comparing the activity of the brain during one of these lucid periods with the activity measured immediately before in a normal dream, the scientists hoped to identify characteristic brain activities of lucid awareness. “The general basic activity of the brain is similar in a normal dream and in a lucid dream,” said Michael Czisch, head of a research group at the Max Planck Institute. “In a lucid state, however, the activity in certain areas of the cerebral cortex,” the more advanced part of the brain, “increases markedly within seconds. The involved areas of the cerebral cortex are the right dorsolateral prefrontal cortex, to which commonly the function of self-assessment is attributed, and the frontopolar regions, which are responsible for evaluating our own thoughts and feelings. The precuneus is also especially active, a part of the brain that has long been linked with self-perception.”