(Previously hosted at Weebly platform, these are my personal notes from the Coursera platform "Synapses, Neurons and Brains" online lesson, taught by Prof. Idan Segev, The Hebrew University of Jerusalem (2013)).
"You, your joys and sorrows, your memories and your ambitions, your sense of personal identity and your free will are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules" - Francis Crick, Nobel Laureate, 1962 - "the father of DNA". This saying implies in many ways that we're a mechanistic, physical machine that generates beautiful (and terrible!) things. Indeed, looking inside the brain one will not find neither spirits nor "Ghosts" in this machine. He/she will find genes, ions, channels, neurons, axons, dendrites and spikes (aka... BOOMS! - Farewell to you as well Prof. Segev, we've had some great moments - Plz, tell Guy to hurry the next series of lectures!!). Click "Read More" to continue!
So what is the route to comprehend the brain? Our brain is plastic, dynamic and eager to do new things and the issue of creativity is very special to human beings. Today's science has made big steps towards the understanding of this special tool, our brain, but the knowledge is still partial. We don't know everything yet. But surely, we Courserians, learned a great deal of things, like: 1. That these are unique times - a world-wide effort to understanding the brain (thus "brainbow", "connectomics", HBP, B.R.AI.N., Clarity and new theoretical efforts). 2. That the Spike (action potential) is a universal "trick" of nerve cells for representation/processing information and that functional neural networks are formed via synapses and PSPs (at dendrites). 3. That these two key electrical signals (spikes and PSPs in the "macroscopic" level) in the brain are carried via specific underlying ions flowing across specific channels (in the "microscopic" level) in the neuron's membrane. 4. That neurons receive thousands of synaptic inputs over their dendritic tree "(synapses are decorating the tree" - great conceptualization!!!) and that the spiking output (which actually "reflects" something about its input) is generated in the axon. So neurons are considered to be a kind of I/O processors. 5. That neurons and the networks they form, compute (the velocity of a car, the weight of a glass, the taste of food, etc). Neurons produce elemental computations but then the network as a whole (system) produces a computation strong or rigid enough to guide our "external-world" behavior as living/communicating organisms. These very sophisticated computations are happening "online" (or in real-time) with the assistance of massively stored memories and their success (efficiency) or failure is determining our survival and our adaptation to the challenges of the physical (and emotional?) world. 6. That the synapse is the most fantastic plastic element, enabling us to learn and change. Plasticity underlies the uniqueness of the brain. 7. That electrical activity of large neural networks corresponds to perception, action and emotions. That brain diseases emerge when this network activity goes wrong. 8. Finally, we've learned that we miss a theory on how to connect brain mechanisms to subjective experience (or on how to integrate our bits of partial understanding into a coherent set or system of a "universal" or total understanding of a phenomenon, (e.g. Alzheimer's).
Free will and Neuroethics The more we know about the brain, the more tools emerge about it. The more we can probe it. And this is frightening (!!!) because knowledge could always be used either as a tool to help or as a tool to harm. For example, the issue of "brain reading": will we ever be able to read - now - somebody's brain and know what he/she thinks? Another related question is the one of "brain intervention". Well, we've seen that this is already happening in daily basis in hospitals (e.g. anti-depressant drugs). Society will eventually have to decide about the "legitimacy" of brain intervention either for repair or other forms of manipulation (enhancement of creativity, enhancement or "upgrade" of happiness, eventually augmenting cognition). The underlying of all ethical implications is the issue of free will. We believe that we're free agents, it's essential for our well-being to feel free, it's fundamental, but are we actually free? And if not, which are the implications for society? Are we robots, in some sense?
Reading thoughts Key issues in this topic are, amongst other things, privacy (who defines/dictates the reader of my thoughts?), reproducibility (accuracy and mistakes due to complexity and constant plasticity) and individuality (how similar/different are our "personal" brains? can we study a specific phenomenon/spike activity and then legitimately generalize and say that "all humans with such a brain pattern of spike activity think exactly the same thing"? In this question the answer is affirmative. By using fMRI (check below) I can identify which brain regions are activated when a face is projected, or a tree, or a car, etc. So yes, without knowing anything about you, I can observe which areas are over-active and safely assume that you're now thinking of the "category" of faces, then of the "category" of plants, and so on. Interestingly enough, if one agrees to be "calibrated", (meaning to be tested by the fMRI for some time by being projected extensively specific images, then the fine-tuned details of specific faces could be recorded and be played back. But again, it would be much of the same approach: I observe activity, I control it by continuous checks and repetition, and then I can say that "when such an activity exists then you think of your wife", you, in your own personal brain. My image of your wife would be something completely different in terms of spikes initiation and localization [and I'm stopping this example here because of obvious reasons and even more obvious implications.......]). So, in general, one can "generalize" about your current thought's conceptual/cognitive category (e.g. "faces", "plants", "vehicles", etc, gross, common things for all humans) but the same thing is not true for guessing the instances of these categories, universally, for all humans... [I don't want to do this but I also can't help it: I DO want/like/wish to believe that my wife's face means something different to other people than it means to me, so in this sense, fMRI would be also an ideal anti-cheating device, so no need for sword duals any more, just challenge your "opponent" for a quick fMRI and if the brain mappings of your wife overlap, well, hmm, just bring this scan to the court.....].
There are many tools to look at the brain. One is the fMRI (Functional Magnetic Resonance Imaging), a non-invasive tool. It can detect brain functions in health and diseases. It can communicate with the brain in vegetative states. Can it detect beliefs? Intentions? Tendencies? More? In the case of fMRI, what is measured is actually blood flow at the active region and not electrical activity. But by examining the amount of blood circulated in an active region, then you can assume that this area must over-produce electrical activity and to do so this area needs energy, which is the oxygen transferred in the blood vessels.
Imaging the brain during aesthetic experience 1. Are there brain areas that are consistently active across subjects when they perceive a painting to be beautiful? 2. Are there brain areas that are consistently active across subjects when they perceive a painting to be ugly? In other terms, are there any neural correlates of beauty? (check experiment details in the video ("Reading thoughts part 2"): the short answer is YES). So for all of us and regardless of our individual liking, the actual "feeling" of liking (or dis-liking) activates a particular region of the brain, for all of us. So whenever you see something, both "ugliness" and "beauty" are manifested in the same areas, but in different proportions. Change in the relative activity in the orbito-frontal cortex correlates with judgement of beauty and of ugliness (beauty is stronger than ugliness). Similarly, change in the relative activity in the motor cortex correlates with judgement of beauty and of ugliness (where ugliness is stronger than beauty). One interesting question is how comes and the motor cortex which is used for movement is actually activated for aesthetic (ugly only) judgements. One possibility is that the ugly visual stimulus is aversive and you want to escape away from it. You want to run! But even at this level (which includes very fine calibration), one can not correlate specific images to all brains. Only categories (liking/dis-liking).
Vegetative states (locked-in) In this cases, fMRI is the only way to communicate with a person not otherwise being able to talk to you. Some of these patients can respond willfully and specifically to a particular question using a particular brain region.
General Issues - Brain Polygraphs (fMRI, EEG)
Success rate? (noise and variability)
Calibration (personal details)
How does it compare with regular polygraphs?
Transcranial Magnetic Stimulation (TMS): a non-invasive probing of the living brain. With this machine, an electrical field can be generated around particular brain regions and so activate (fMRI records) a large group of cells for enhancing reasons (local stimulation). This machine was found useful for some depressant patients.
So how free are we? The example of Phineas Gage, Vermont, USA, 1848. He is probably the most famous patient to have survived severe damage to the brain. He is also the first patient from whom we learned something about the relation between personality and the function of the front parts of the brain. Some months after his accident (a rod went through his skull), probably in about the middle of 1849, Phineas felt strong enough to resume work. But because his personality had changed so much, the contractors who had employed him would not give him his place again. Before the accident he had been their most capable and efficient foreman, one with a well-balanced mind, and who was looked on as a shrewd smart business man. He was now fitful, irreverent and grossly profane, showing little deference for his fellows. He was also impatient and obstinate, yet capricious and vacillating, unable to settle on any of the plans he devised for future action. His friends said he was "No longer Gage".
Are we completely defined by the deterministic nature of physical laws? Are we essentially sophisticated automatons only, with our conscious feelings and intentions tacked on as epiphenomena with no causal power? (cf. Thomas H. Huxley). Or do we have some independence in making choices and actions, not completely determined by the known physical laws? The greatest gift which humanity has received is free choice. It is true that we are limited in our use of free choice but the little free choice we have is such a great gift and is potentially worth so much that for this itself life is worthwhile living (Isaac Bashevis Singer, 1968, Nobel Laureate).
The most dramatic beginning of the research of free will are the Benjamin Libet experiments. He was using EEG on the skull, a non-invasive technology. (check "Free Will" video for details). Readiness potential: it was found that there was a 2 second gap between the brain's started to plan the action and the personal, individual, expressed awareness of the person declaring the exact moment which he thought he actually decided to perform this action... So, what kind of free will do I have since there is this unconscious 2-sec gap? Libet's findings have been widely taken to show that since our brain has already started preparing to flex the wrist before we even become aware of our intention to flex it, our supposedly free will is not free at all. Rather, our brain has decided for us and has started a causal chain leading to the finger-bending, before we become aware of our decision. Thus, our will appears determined and causally irrelevant. Furthermore, there are new results (2009) where patients that undergo brain surgery are implanted with specific electrodes in the open skull and you can stimulate locally and see some amazing phenomena, for example, if you take a specific area and stimulate it with low-intensity current, the patient reports: "I felt the desire to lick my lips". He is consciously reporting that he wants to do so. He doesn't move the tongue. The stimulation does not make him move his tongue but it rather affects his will to move it, a will that he explicitly expresses. For higher stimulation, the same patient reports: "I moved my mouth, I talked, what did I say"? He did not intentionally moved his mouth, he just reports that he felt his mouth moving and is wondering about what had being said. In another region (premotor regions), low and strong stimulation can cause movement (e.g. of limbs) without awareness. So one can intervene with the brain by low or strong stimulation and suddenly the "will" vanishes. So, even if we come to the decision, which slowly is creeping in, that there is no free will, "we need to continue to assign value to our behavior because it is essential for organizing society" (Wolf Singer, director of Max Planck Institute, 2004).
Farewell words by Prof. Idan Segev
These are unique times for the brain. In the next decade we will see huge changes in both the structure of brain research, new experimental methods and new theoretical approaches.
The brain is plastic; so we (and the world) are constantly changing (action-perception loop). We are the only animals that change the world so fast. We however tend to "judge" things as if they are deterministic - "good" and "bad", "right" or "wrong". We must be rather cautious with such "universal" truths or certainties, since we humans are a constantly adapting, extremely complex, apt and keen to continuous change, dynamic system.
(unfortunately...) THE END