Informational Digest Bulletin From San RaffaeleFoundation and Tosinvest Sanità (No. 23).Consciousness: No Matter What Is, No MatterWhere Is—An Edge Shot Approachjppi_269 231..232

Marco Sarà*, Paolo Onorati†,‡, Giorgio Albertini†,‡, andFrancesca Pistoia**Post-Coma Intensive and Rehabilitation Care Unit; †ChildDevelopmental Department, San Raffaele Cassino, Cassino; and‡Child Developmental Department, IRCCS San Raffaele Pisana,Rome, Italy

Research on the so-called “neural correlates of consciousness”(NCC) has come out of its niche, becoming a “trendy” matterboth in scientific literature and mass media. It is a consequence ofknowledge forthcoming about “vegetative state” (SV) and “mini-mally conscious state” (MCS). The idea of losing command ofourselves is indeed one of the greatest fears of this century. We areaware of the fact that we can find ourselves in a not-so-definedstate (that may be definitive), which could be of more or lesscomplete dependence on the others for an indefinite time. Thus,the reflection on the nature of consciousness, apart from repre-senting one of the central scientific challenges of this new millen-nium, is also an urgent human necessity.

While the problem of consciousness is no longer an exclusiveobject of philosophy, the discussion on the social consequences ofthese syndromes where there is impairment of consciousness hasbegun to raise ethical matters. Generally, all the scientific mattersimply two kinds of fundamental questions: (1) those related tothe nature of the problem itself; and (2) the possible solutions ofthis particular problem. Concerning the nature of consciousness,we face a “constitutional dilemma” for consciousness is notdefined in a univocal way by various researchers over the world.What are the consequences of this heterogeneity? The mostobvious deduction we can draw is that we have not definedyet what exactly is consciousness. This leads to inevitableconsequences of scientific procedure: the lack of prerequisites ofreproducibility.

For example, “apples fall down,” and when Newton gave thisphenomenon a certain mathematical description, he referred tosomething that everybody could observe in an absolutely compa-rable way. Thereby, if—for example—a Dutch or Australian sci-entist would have liked to verify the Newton equations, he wouldnot have had problems doing it, confirming the laws of gravity.Unfortunately, with respect to consciousness, the situation isnot the same given that a certain discovery made in a Japaneselaboratory may not be confirmed by another laboratory where

this problem (and also the expected answer) is defined in anotherway.

Contemporary researchers assume consciousness as the con-dition in which we wake up in the morning after a no-dreamssleep (e.g., John Searle), while for many others, it is a combinationof perception, synthesis, subjectivity, and free will. For somescientists (including the neurophilosopher Thomas Metzinger),consciousness itself has a lot of illusive elements, as well as freewill (e.g., Benjamin Libet, Martin Heisenberg, and others).According to others, the only element that can be examined in ascientific way is the exact moment when a subject (obviouslycollaborative) confirms his or her awareness of a certain stimulus.To conclude, it is not easy to reproduce and compare the resultsachieved in different laboratories of the world: We put forthvarious questions, and thereby, the possible answers can beincomparable. In our opinion, dividing consciousness in partsimplies “the paradox of the parts of an unknown whole” (Sarà &Pistoia, 2010), which leads us to wonder whether it is possible tostudy the distinct parts of a whole that we have not yet describedin its entirety. Another important limit in studying patients withSV and MCS is represented by the considerable heterogeneity ofbrain damages that cause the above syndromes.

However, we can affirm that the scientific literature is movingtoward a “connectionist” view of cognitive functions and there-fore of consciousness itself. The concept of functional integrationis more and more spread in neuroscience. Particularly, the phe-nomenon of consciousness would emerge from dynamic shapingof neural functional aggregates even between distant cerebralareas. We have used the verb “emerge” to represent the types ofphenomena (called “emergence phenomena”) among which,according to different authors, could be also consciousness. Anemergent phenomenon is something that draws on what alreadyexists in that space assuming its own identity. For example, a flockof birds (which is a dynamic aggregate of elements previouslyindependent from each other), in aggregate, forms a new andclearly recognizable entity. We know that the aggregate will adoptits own behavior with advantages for itself and, above all, theelements that form it: single birds. The phenomena of emergencecan be the subject of studies even when considering the laws ofquantum mechanics with important advantages taking intoaccount the matters related to nondeterministic behavior ofso-called “voluntary” mental activity. An emergent phenomenonmust necessarily be regarded in its entirety (also in line with theparadox of the parts of an unknown whole).

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Coming back to problem of the consciousness definition, weask ourselves: at which point does the lack of its unique definitionentail objective difficulties in clinical practice? Is it really indis-pensable to have a univocal definition of a certain physiologicalfunction to “cure it”? We know that medicine deals daily withhuman lives without having a clear concept of “life.”

Our team at the Post-Coma Intensive and RehabilitationCare Unit (at San Raffaele Cassino) has chosen an “edge shot”approach. If the location of consciousness has not been found yet,does there exist a method to assess whether the injured residualbrain is still able to “let emerge” vast functional connections,which are considered the source of consciousness? Our aim is tobypass the following problems: (1) the lack of univocal definitionof the matter; (2) the absence of patient’s collaboration (uncon-scious by definition); and (3) the lack of knowledge on the“circuit” or, rather, the combination of cerebral areas and connec-tions, which is the minimum indispensable to permit the arisingof consciousness.

THE LACK OF UNIVOCAL DEFINITIONOF CONSCIOUSNESS

We have chosen an approach based on evaluation of residualnonlinear dynamics in a physiological time series after a severebrain injury. Nonlinear outputs show high levels of unpredict-ability, this peculiarity being easily recognizable, for example, inthe blood pressure, heart rate, and electroencephalography (EEG)signal time series. Thus, unpredictability may be regarded as con-stitutional behavior of biological complex systems. As a matter offact, it is quite intuitive that the higher the evolutionary level of abiological species, the lower is the probability to predict its behav-ior. What about complexity? A complex system is composed ofinterconnected parts that as a whole exhibit one or more proper-ties (behavior among the possible ones), which are not obviousfrom the properties of its individual parts. This feature is alsocalled “emergence” (Joslyn & Rocha, 2000). As stated previously,consciousness may be regarded as an emergent phenomenon.Because the degree of unpredictability may be stated as acomplexity-related parameter (which reduction reflects thesystem “decomplexification”), we can assume that a reduction ofnonlinear behavior of one or more physiological measures in apatient with disorder of consciousness may indicate pooroutcome. We have evaluated recently the possible prognostic bothof nonlinear analysis of heart rate and EEG signal, which con-firmed our hypothesis (Sarà et al., 2008).

THE ABSENCE OF PATIENT’S COLLABORATION

We should take into account the growing body of evidenceson “covered” mental/neuronal activity in patients with MCS.

From our point of view, all the patients with recent severe braininjury should be considered unresponsive (rather than uncon-scious) until proven otherwise. Both from anatomical andphysiological perspectives, a certain degree of overlap between“locked-in-syndrome” and “disorder of consciousness” isexpected. This possibility should be evaluated as soon as possibleby means of motor evoked potentials and magnetic resonance(MR) tractography. Even the evidence of other communicativeimpairment (i.e., aphasia) should be looked for.

WAITING FOR NCC

Our approach, which has a theoretical background incomplex systems theory and in nonlinear analysis, is free fromnecessity to know a priori “where” and/or “what” the NCC are.The approximate entropy (ApEn) represents an intriguingrelation with the degree of functional isolation of a system. So ifApEn values are widely reduced, we can affirm that in anyway, nokind of large cerebral/neural networks will work. In other words,any possible “Ghost Neural Network” will not function in anenvironment with a high degree of functional isolation. We haverecently successfully tested this hypothesis (Sarà et al., in press).

ACKNOWLEDGMENT

We thank Dr. Katia Veter for her helpful editing for medicalEnglish.

REFERENCES

Joslyn, C., & Rocha, L. (2000). Towards semiotic agent-based models ofsocio-technical organizations. Proceedings of the AI, Simulation andPlanning in High Autonomy Systems (AIS 2000) Conference(Tucson, Arizona). Retrieved on June 15, 2010, from ftp://wwwc3.lanl.gov/pub/users/joslyn/ais005.pdf

Sarà, M., & Pistoia, F. (2010). Defining consciousness: Lessons frompatients and modern techniques. Journal of Neurotrauma, 27, 771–773.

Sarà, M., Pistoia, F., Pasqualetti, P., Sebastiano, F., Onorati, P., & Rossini,P. (in press). Functional isolation within the cerebral cortex in veg-etative state: A non linear method to predict clinical outcomes. Neu-rorehabilitation and Neural Repair.

Sarà, M., Sebastiano, F., Sacco, S., Pistoia, F., Onorati, P., Albertini, G.,et al. (2008). Heart rate nonlinear dynamics in patients with persis-tent vegetative state: A preliminary report. Brain Injury, 22, 33–37.

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