Materialisere selvet
Neuropsykologen og -biologen V.S. Ramachandran opridser i artiklen The Neurology of Self-Awareness, fra den 1. august 2007, nogle af de materialistike forhold omkring selvet, det som vi også kalder bevidstheden.
What is the self? How does the activity of neurons give rise to the sense of being a conscious human being? Even this most ancient of philosophical problems, I believe, will yield to the methods of empirical science. It now seems increasingly likely that the self is not a holistic property of the entire brain; it arises from the activity of specific sets of interlinked brain circuits.
En af de interessante spørgsmål i forhold til den bevidstedhedsform vi har er hvordan den har udviklet sig. Nogen forskere har foreslået at den har udviklet sig på baggrund af gevinsten ved at kunne anticipere hvad en anden vil gøre i fremtiden. V.S. Ramachandran udtrykker sin tilgang:
Specifically, I suggest that “other awareness” may have evolved first and then counterintutively, as often happens in evolution, the same ability was exploited to model ones own mind — what one calls self awareness. I will also suggest that a specific system of neurons called mirror neurons are involved in this ability.
Spejlneuronerne, (som egentlig kræver en særegen introduktion i sig selv, kommer senere) spiller ifølge Ramachandran en væsentlig rolle i forhold til den evolutionære udviklingen af bevidstheden.
Primates (including humans) are highly social creatures and knowing what someone is “up to” — creating an internal simulation of his/her mind — is crucial for survival, earning us the title “the Machiavellian primate”. In an essay for Edge (2001) entitled “Mirror Neurons and the Great Leap Forward” I suggested that in addition to providing a neural substrate for figuring out another persons intentions (as noted by Rizzolati’s group) the emergence and subsequent sophistication of mirror neurons in hominids may have played a crucial role in many quintessentially human abilities such as empathy, learning through imitation (rather than trial and error), and the rapid transmission of what we call “culture”. (And the “great leap forward” — the rapid Lamarckian transmission of “accidental”) one-of-a kind inventions.
Naturen af selvet
Ramachandran mener således at spejlneuronerne også spiller en væsentlig rolle i forståelsen af selvets natur. Kort sagt mener han at den evne der var en evolutionær fortrin, at kunne bedømme andres fremtidige handlinger, blev vendt indad og således skabte forudsætningen for det vi kalder bevidsthed, hvor vi føler at vi kan anskue og bedømme os selv:
How does all this lead to self awareness? I suggest that self awareness is simply using mirror neurons for “looking at myself as if someone else is look at me” (the word “me” encompassing some of my brain processes, as well). The mirror neuron mechanism — the same algorithm — that originally evolved to help you adopt another’s point of view was turned inward to look at your own self. This, in essence, is the basis of things like “introspection”. It may not be coincidental that we use phrases like “self conscious” when you really mean that you are conscious of others being conscious of you.
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the ability to turn inward to introspect or reflect may be a sort of metaphorical extension of the mirror neurons ability to read others minds. It is often tacitly assumed that the uniquely human ability to construct a “theory of other minds” or “TOM” (seeing the world from the others point of view; “mind reading”, figuring out what someone is up to, etc.) must come after an already pre- existing sense of self. I am arguing that the exact opposite is true; the TOM evolved first in response to social needs and then later, as an unexpected bonus, came the ability to introspect on your own thoughts and intentions.
Dette, spejlneuronernes rolle, er som Ramachandran skriver i sin artikel, ikke fyldestgørende for at forklare selvet, men det giver nogen stærke indikationer om hvordan vi fremover kan søge bedre forståelse af selvet. Andre primater har også spejlneuroner i funktion, men har samtidig ikke en selvbevidsthed. Hvorledes adskiller denne primat fra andre på dette område? Hvilke fysiologiske omstændigheder har gjort det muligt for selvbevidsteheden at udvikle sig?
They may have to reach a certain critical level of sophistication that allowed them to build on earlier functions (TOM) and become linked to certain other brain circuits, especially the Wernickes (”language comprehension”) area and parts of the frontal lobes.
Undersøgelser af forskellige patienter med forskellige neurologiske skader eller deformiteter giver også et væsentligt fingerpeg om at det er i forbindelse med spejlneuronerne at vi skal hente væsentlige aspekter af vores forståelse af selvet. Og Ramachandran er også optimistisk i forhold til neurovidenskabens rolle i forhold til at forstå og kortlægge, det som han kalder “Science’s greatest riddle“.
Some years ago we examined a patient with a syndrome called anosognosia who had a lesion in his right parietal lobe and vehemently denied the paralysis. Remarkably the patient also denied the paralysis of another patient sitting in an adjacent wheelchair! (who failed to move the arm on command from the physician.) Here again was, evidence that two seemingly contradictory aspects of self — its the individuation and intense privacy vs. its social reciprocity — may complement each other and arise from the same neural mechanism, mirror neurons.
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Have we solved the problem of self? Obviously not — we have barely scratched the surface. But hopefully we have paved the way for future models and empirical studies on the nature of self, a problem that philosophers have made essentially no headway in solving. (And not for want of effort — they have been at it for three thousand years). Hence our grounds for optimism about the future of brain research — especially for solving what is arguably Science’s greatest riddle.
Hvis man vil hører eller læse, hvilket jeg vil anbefale at man gør, mere af V.S. Ramachandran er der fx denne video, hvor han diskutere hans seneste bog “A Brief Tour of Human Consciousness“, fra 2004, eller man kan kigge på nogle af de forskellige artikler han har skrevet for Edge her, hvor man også kan finde et link til hans egen hjemmeside, hvor der er flere henvisninger til forskellige publikationer, interviews mv.
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