I’ll bet if I say the phrase “brain in a jar” or “brain in a vat,” you’ll conjure up one of many science fiction scenarios that explores this idea: that all your experiences and surroundings are a fabrication constructed by your brain. Perhaps they are self generated like the Boltzmann Brain. Or maybe evil geniuses are designing our experiences through stimuli straight into our heads, like in The Matrix.
There are a number of issues that arise when you consider whether a full fabricated reality like The Matrix is plausible, but a good place to start is whether external stimuli to the brain can create experiences at all, or trigger memories of experiences gone by, at least.
The following is an excerpt from NeuroScience Fiction by Rodrigo Quian Quiroga, a new book that explores how modern neuroscience is turning iconic science fiction concepts into reality. In this section, the author discusses real world experiments that edge toward finding out just how plausible a brain-simulated world could be. Printed here with permission of the publisher.
The modern version of Descartes’s evil genius and solipsism is what is known as the brain in a vat argument drafted by American philosopher Hilary Putnam in 1981. Let’s imagine an evil scientist (or Descartes’s genius), who surgically extracts our brain and places it in a big jar with a solution overflowing with nutrients to keep it alive. Let’s also imagine that he connects all of our nerve terminals to an incredibly powerful supercomputer, capable of simulating the external reality by using complex electrical stimulations of different groups of neurons. For example, the supercomputer stimulates neurons that represent the concepts of sand, palm trees, and the sea, and leads us to believe we are on a beach. The argument, similar to the construct of The Matrix, is somewhat crazy but very interesting, because if we lack arguments to demonstrate that we are not a brain in a vat, then we can’t state anything about the existence of the external world.
In neuroscience, there are several examples of how directly stimulating the brain can alter and even create different feelings. For example, when electrically stimulating in monkeys an area involved in the perception of movement (which in neuroscience is known as MT or V5), scientists from Stanford University showed that this stimulation changed the animals’ perception of the direction of motion of a group of dots on a screen. Likewise, a group of Iranian researchers showed that electrical stimulation of an area dedicated to facial recognition (the inferotemporal cortex) made the monkeys tend to report that blurry images they were shown corresponded to faces and not to other objects. But the most amazing studies describing the effects of electrical stimulation on the brain were done more than half a century ago by neurosurgeon Wilder Penfield with humans.
In chapter two, we mentioned that epileptic patients who do not respond to medication could have surgery to remove the area that causes the epileptic seizures. The success of such surgeries depends, on one hand, on finding with the best possible precision the seizure focus (and as we discussed earlier, to do so, in many cases, intracranial electrodes are implanted in the brain) and, on the other hand, on not harming areas that are vital for the patient’s functionality. For example, if by mistake part of the motor cortex is compromised during the surgery, the patient would suffer paralysis; if the visual cortex is compromised, the patient could become blind; and so on. Given that the location of these vital areas varies from patient to patient, Penfield developed an electric stimulation protocol to define their precise location. This procedure was done while the patients were awake and their brains were uncovered (accomplished by temporarily removing the upper part of the cranium), all the while using local anesthesia since the brain itself doesn’t have pain receptors. Penfield then stimulated the areas around the sensory and motor cortices, defining where the stimulation produced a tickling sensation or movements of different parts of the body, like the fingers, the tongue, or the lips. He also stimulated around the language areas while asking the patient to name different objects, or he stimulated areas in the visual cortex and produced different hallucinations—patients said they saw colored stars, and so on.
The most spectacular results took place when Penfield stimulated the areas related to memory in the temporal lobe, because in many cases he was able to reactivate different memories of the patients, who seemed to be reliving their past like a movie. One patient claimed to remember being in her kitchen listening to the voice of her son who was playing outside, and said she was conscious of the neighborhood’s sounds, the passing cars, and how they were a danger to her son. When stimulating a specific point in another patient’s temporal cortex, she reported hearing the voice of a woman and a man who were calling her somewhere along a river, and the stimulation of another spot brought up a familiar memory of being in an office with desks and a man leaning on one of them with a pencil in his hand. Penfield contended that these memories were stored in the temporal lobe and that the stimulation simply evoked them, triggering the flow of consciousness, just as the taste of Marcel Proust’s famous madeleine fired memories of his childhood in Remembrance of Things Past.
I would also like to mention a very interesting result from my colleague Itzhak Fried, the neurosurgeon whom I have been working with for years on the study of neural recordings in epileptic patients—who is, incidentally, also a deep admirer of Penfield. Itzhak showed that stimulation of the supplementary motor area in a patient triggered his laughter. When they asked him (during the surgery) what he was laughing about, the patient said that the team of surgeons “looked very funny, all around him.”
To sum up, the results obtained by different groups of neuroscientists show that electrical stimulation can elicit different feelings and even evoke memories.
NeuroScience Fiction: From “2001: A Space Odyssey” to “Inception,” How Neuroscience Is Transforming Sci-Fi into Reality―While Challenging Our Beliefs About the Mind, Machines, and What Makes us Human
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