gonna feel happy in 3, 2, 1 …

… GO! In this precise moment, you’re feeling an inexplicable feeling of happiness, aren’t you? Oh yes, I knew that. How? Simple, I computed it, and maths is not an opinion.

The equation reported a few lines below here is the expression of a computational model of momentary subjective well-being proposed in this article. Basically, it allows to compute momentary happiness based on expectations, rewards and past outcomes. The study was conducted on 26 subjects who had to deal with monetary options. In each trial, each subject had to choose between a certain option (win the sum X) and a gamble (gamble the sum Y). “Chosen gambles were resolved after a 6-s-delay period. Every two to three trials, subjects were asked to indicate” how happy they were at that precise moment.

I’ll leave you the pleasure to read the article for more details; in this post, we’ll simply take a look at the equation terms and try to understand them 🙂

• the variable t is not the time, but the current trial (decision whether to win or gamble). The variable j is a past trial;
• the terms w0, w1, w2 and w3 are weights assigned to the influence estimated for different event types;
• the forgetting factor 0 ≤ γ ≤ 1 makes “events in more recent trials more influential than those in earlier trials“;
• CR means Certain Reward, the certain option, while EV is the Expected Value of the alternative gamble. So, CRj and EVj are the average rewards of the trial j;
• RPEj is the difference between experienced and predicted rewards “on trial j contingent on choice of the gamble“.

Basically, at each trial j, if CRj is chosen then EVj = 0 and RPEj = 0; but if the subject chooses the gamble, then only CRj = 0, while EVj and RPEj are based on previous experience. In any case, these three quantities (CR, EV and RPE) are all linked to dopamine activity. Dopamine is a neurotransmitter (chemical released by nerve cells) which, in human brain, is responsible for sending signals to other nerve cells. The researchers “hypothesized that these dopamine-related quantities might explain momentary happiness“.

Using computational modeling, it was shown that “emotional reactivity in the form of momentary happiness in response to outcomes of a probabilistic reward task is explained not by current task earnings, but by the combined influence of recent reward expectations and prediction errors arising from those expectations“. In more general terms, happiness can be modeled as emotional reactivity to recent rewards and expectations. This allows to investigate the neural mechanisms which underlie the relationship between ongoing happiness and life events.

The researchers claim that their key finding is that “happiness is related to quantities associated with temporal difference errors that phasic dopamine release is thought to represent. At the very least, this hints at a link between dopamine and emotional state, consistent with suggestions that this neuromodulator plays a role in mood regulation in healthy and depressed subjects“. Upon further investigation, any scientific evidence that emotional state is related to brain and behavior could provide a framework for the development of model-based assays for the interpretation of mood disorders.

Mind-Readers: the future of Brain-Machine Interfaces

article written by Melissa Walmesley for andreacollo.wordpress.com

Late last year a woman sat in a wheelchair she had been bound to since a stroke 15 years earlier left her quadriplegic, with no use of her body below the neck. She then reached out, grabbed a cup of coffee and put it to her mouth, taking a sip. This was no miracle, just another step in the growing body of research into neuroprosthetics, a revolutionary technology which can work alongside functional rehabilitation robotics and that will allow paralyzed people the ability to move, feel and communicate again in the very near future.

Brain-Machine Interfaces (BMIs) and Brain-Computer Interfaces (BCIs) are devices that use a neural implant to record and process electrical information from the brain into actions that a computer, robot or virtual avatar can perform. Each implant picks up minute electrical impulses from hundreds of neurons around it. Each time a neuron fires, that is, sends an impulse, that impulse is recorded. The timing of these impulses and the rate at which they occur is correlated to the actions or sensations we want to perform or that we feel. For instance, as you move your eyes to read this sentence, certain cells in your brain increase their firing rate which will signal the muscles surrounding your eyes to produce the correct movement to move your eyes from left to right. These firing rates are then used as inputs into mathematical algorithms developed over many years which try to work out what the intended movement associated with the rate is. Researchers do this by training the algorithm, giving it a set of firing rates of all these hundreds of neurons and a sample of the corresponding movement the firing produced (by simultaneously recoding the position of a joystick a research animal might be moving or recording its position using motion capture software). The algorithm then works out how the firing correlates to the movement. Once the algorithm is trained they give it new data and it can predict what is supposed to happen. This output can then be used to produce a movement, such as a cursor moving on the screen, or the robotic arm moving to pick up the cup.

A symphony of activity – This technique has only recently been made possible by advances in technology that allow the researchers to record from many brain cells at once. The human brain is nothing but a connection of billions and billions of cells and no single cell is responsible for a single action or thought, rather thoughts, actions, feelings are all the combination of ensemble of neurons, all increasing or decreasing their firing at once. Some researchers are already starting to look at ways to record from thousands or tens of thousands of cells simultaneously, even though this is still a tiny fraction of the amount in the brain. It is only when we get to such numbers that we truly start to see how the human brain works as a symphony. There is a number of hypotheses about how the brain is compartmentalized into areas of specialization and some researchers spend their entire lives dedicated to a single square millimeter of brain real estate. However, the brain is a mass of interconnection, so you have to look everywhere to get a feel for how it works. Though most BMI-related work has concentrated so far on movements, researchers want to get a deeper understanding of the entire structure. Areas such as those associated with movement planning and feeling incoming sensations are the most investigated, as well as deeper structures such as basal ganglia and the thalamus (they play a key role in producing body movements and are damaged in such diseases as Parkinson’s disease). Others are looking at implanting devices in memory areas of the brain, addiction centers or pain centers to try and help with memory loss and addiction, or work as painkillers.

Though the field is moving quickly, some advise caution. The pioneering implants in humans have so far all been ‘wired’ implants. That is, they all have a direct connection from the brain to the outside world. For such a technology to really be able to be used in humans it has to be wireless – the chip in the brain has to be able to be sealed in and then communicate wirelessly with any computer or robot in the outside world. The brain exists within its own cocoon within the body, sealed off to prevent infection as much as possible – a direct link through the skin to the outside world would have a strong likelihood of leading to an infection for the patient, who, being in a paralyzed state or injured or having a disease, may well already be in a compromised state.

Feeling as well as moving – The next step in BMI is to use these implants not only for recording the brain activity associated with different movements, but also to try and mimic sensation. If you imagine a person using a neuroprosthetic arm to pick up a coffee cup, not only they have to produce the movement, they also need to feel the cup so they can exert the correct pressure, know how heavy it is and know how hot the coffee inside is. Ideally you would want to be able to send all this information directly back into the brain so the person can use the arm as naturally as possible. Researchers have been able to use such feedback to mimic textures, so that an animal moved a computer avatar arm between different objects and felt them to decide which is the correct object to pick up with the arm. All movements require sensory feedback to be able to be performed correctly and it is a great challenge nowadays to allow people who will eventually use this technology to be able to live lives as rich as possible. Stimulation can be used in other brain areas to produce other body sensations or even emotional feelings.

Neuroprosthetics open up an entirely new field of not only medicine, but possible human experience as implants could be produced to change the way you think, how you remember or what you remember. Caution will be needed, as with any new technology, but currently the benefits have started outweighing the possible downsides of such technology.

the Human Brain from 1 to 86 billions

1 – Apart from some obvious exceptions, the average person has one brain. It’s located inside the skull and represents the center of the nervous system. The brain exerts a centralized control over the other organs of the body. Brain death is the irreversible end of brain activity; it is used as a legal indicator of death in many jurisdictions.

2 – The human brain has two hemispheres that function differently. This means that each hemisphere, left or right, controls different functions. Language, math and logic are mainly controlled by the left hemisphere, while creativity, spatial abilities, visual imagery and music depend on the right one. A funny thing is that the right side of the brain controls muscles on the left side of the body, and vice versa. Therefore, damage to one side of the brain will affect the opposite side of the body.

3 – Three pounds is the average weight of the human brain. Switching to more common units, we have about 1.3 kg of mass in about 1130 cubic centimetres (cm3, or cc). Take the quantity of water contained in one bottle of 1 liter plus one coffee cup and you’ll have the same volume.

4 – Each cerebral hemisphere is divided into four lobes. Their identification is made by considering sulci and gyri, respectively the grooves and the bumps that can be seen on the brain surface. The Frontal Lobe is located in front of the central sulcus and is concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving. Behind the central sulcus there is the Parietal Lobe, that treates the perception of stimuli such as touch, pressure, temperature and pain. Below the lateral fissure we have the Temporal Lobe, devoted to perception and recognition of auditory stimuli (hearing) and memory (hippocampus). At the back of the brain, behind the parietal and temporal lobes, there is the Occipital Lobe, mainly concerned with many aspects of vision.

5 – Somebody started arguing that the human brain makes us see ourselves five times more beautiful than we actually are. If you accidentally read that somewhere, it’s junk science. This is not scientific at all, but it may be interesting to have a look at this video.

6 – The first six months of life are really important for brain development. During the first six months of life, babies gradually gain information about the world around them. After depending mainly on their caregivers, babies grow and develop faster in the first year than any other year. There is a host of techniques to boost babies’ cognitive development during their first 3-6 months of life (an example here), mainly by reading and talking to them, making them interact with toys and people, proposing them different situations in order to enhance their senses, and so on.

7 – seven items is the typical capacity of the so-called “brain’s working memory”. As explained on this website, countless psychological experiments have shown that, on average, the longest sequence a normal person can recall on the fly contains about seven items. Typical scenarios: recalling a phone number, or the items from a mental grocery list (that’s why we write it down!), or all the names of the seven dwarfs (one of the hardest things in life…). Comparing the human brain to a computer, the working memory is somehow the RAM, while the long-term memory is the hard drive. The complex brain activity imposes the limit of seven items to the working memory, which provides continuity from one thought to the next and allows quick conversations and computations. The very complex biochemical machine we have inside our head continuously manages a stunning number of interneuronal communications, at each time instant. Mathematical models can estimate the huge network of firing neurons, thus estimating the working memory’s capacity… that is, on average, only seven items!

Unfortunately, we don’t have time (and space), here, to get to 86 billions, that is the number of neurons in the human brain (according to the latest plausible estimate). One billion is 10⁹, or 1 000 000 000, or a thousand millions (10³×10⁶). And yes, we have 86 times this quantity of neurons in our three pound magic box!

other source: this amazing website

Mind-controlled Helicopter

Awesome news!   🙂   (from this website)

University of Minnesota researchers have been able to control a small helicopter using only their minds, pushing the potential of a technology that could be used to help paralyzed or motion-impaired people interact with the world around them.

The controls for the mini-vehicle, which looks and flies much like any remote controlled helicopter, are otherwise fairly simple: if you want it to go up, think about it going up. If you want it to go down, think about it going down. There have been other brain controlled devices before, but the project created by Professor Bin He’s team offers extremely smooth control — and doesn’t require drilling holes in your head. “It’s completely non-invasive. Nobody has to have a chip implanted in their head!” said Brad Edelman, a graduate student working on the project.

The technology used is an electroencephalography (EEG) cap with 64 electrodes that fits over the head of the person controlling the helicopter. The researchers map the controller’s brain activity while they perform certain tasks (for example, making a fist or looking up). They then map those patterns to controls in the helicopter. If the researchers map “go up” to a clenched fist, the copter goes up. After that, the copter will go up automatically when the controller clenches a fist.

Of course, the brain patterns can be more subtle than fist clenching and the process can be trained so that no physical actions are necessary. Usually, to get even finer control over devices via brain power, the scientists need to dig deeper. Literally. With devices installed into the brain directly, fine motor control over things such as computer cursors is possible. However, the University of Minnesota test shows that this brain invasion may not be needed except in very specific cases. The control is precise enough take the helicopter through a relatively complex obstacle course.

Professor He, the team leader, feels that the non-invasive approach has a far broader appeal for people who don’t want people cutting into their skulls. “My entire career is to push for noninvasive 3-D brain-computer interfaces, or BCI,” He said in a release. “[Researchers elsewhere] have used a chip implanted into the brain’s motor cortex to drive movement of a cursor [across a screen] or a robotic arm. But here we have proof that a noninvasive BCI from a scalp EEG can do as well as an invasive chip.” For He, this distinction is important, because he sees it as the best way to popularize the technology. “The ultimate application really is to benefit disabled patients who cannot move or patients that suffer with movement disorders,” Prof He told the BBC. “We want to to control a wheelchair, and turn on the TV, and most importantly — this is my personal dream — to develop a technology to use the subject’s intention to control an artificial limb in that way, and make it as natural as possible.”

The technology isn’t just for people who have lost normal function in their bodies, Proffessor He also sees the technology as something that could “enhance function beyond what we can accomplish,” for everyday people. There are still some issues with the technology as it stands. The five subjects the researchers tested were only able to control the helicopter with about 90% accuracy. That’s high, but not perfect for tasks which need more precision. Additionally, there was a slight latency between the thought input and the copter reacting. “I think the potential for BCI is very broad,” He said in a release. “Next, we want to apply the flying robot technology to help disabled patients interact with the world. It may even help patients with conditions like stroke or Alzheimer’s disease. We’re now studying some stroke patients to see if it’ll help rewire brain circuits to bypass damaged areas.”

How many limbs do you actually perceive?

A famous movie showed us the advantages of having more limbs than usual. A common person with, for example, six independent arms could be stronger than normal, more dexterous and more efficient in killing annoying spiders. The four additional arms would actually be part of his body, normally connected to his motor nerves in order to be very accurately controlled by his brain. He would also feel pain if one of his additional arms was hurt.

Try to figure out the sensation, I mean the physical sensation, of being able to control each single limb of your body. Focus on all the feelings that you can actually experience with your legs and arms (temperature, pain, sense of touch, shape recognition, EVERYTHING!): it’s amazing. Each part of our body is innervated in a way that determines to which extent we “feel” neuro-biological phenomena. Our nerves get grouped in the spinal cord and the data they collect are transmitted up to the brain. In different areas of the primary motor cortex we can actually find a precise mapping of all the different body regions that are directly responsible for the exchange of sensory and motor information. So, for instance, it is possible to localise the motor cortex area corresponding to the tip of our left thumb.

Now, the fact is that innervation of body regions is not uniform at all. Our lips are clearly more sensitive than our elbows. These differences are respected at the level of the motor cortex. Basing on the amount of cerebral tissue or cortex devoted to a given body region, some smart people proposed a funny representation of primary motor cortex anatomical divisions (picture on the left). In this bizarre cortical homunculus, the size of each body region is proportional to how richly innervated that region is, and not to its actual size. This brain representation develops over time and is different for each individual. What is sure is that our brain “feels” the presence of each single part of our body according to this representation at the level of the primary motor cortex. This leads us to the concept of “body within the brain”:  one’s hand, or toe, or nose exist as soon as it is represented by a specific region of the primary motor cortex.

Now let’s get back to the man with six arms. In his cortical homunculus we will be able to recognize each single arm region. This is due to the fact that, in his case, a cortical reorganization takes place in order to best define its personal “body within the brain” representation, including its peculiarities. Cortical reorganization is somehow continuous during the whole life and corresponds to the redistribution of nerves in those areas that undergo some changes, becoming different than before. This process is not immediate and takes some time. In some cases, as we are going to see, some problems may arise.

Amputees may suffer from the Phantom Limb Syndrome. What’s that? Below here we have a nice definition, found on this website:

Phantom limb syndrome is the perception of sensations, usually including pain, in a limb that has been amputated. Patients with this condition experience the limb as if it were still attached to their body, as the brain continues to receive messages from nerves that originally carried impulses from the missing limb. The exact cause of phantom limb syndrome is unknown. Presumably, the sensations are due to the brain’s attempt to reorganize sensory information following the amputation. The brain must essentially “rewire itself” to adjust to the body change.

Approximately, 60 to 80% of amputees suffer from this syndrome. They might feel the sensation of having the missing limb shorter or longer than normal, or positioned in a wrong and painful way, or they may experience tingling, cramping, heat, and cold sensations in the portion of the limb that was removed. Why does this happen? Even if the limb is no longer part of the body, the nerve endings at the amputation site continue to send signals to the brain. At the level of the primary motor cortex, the brain “thinks” the limb is still there! At the same time, slowly, cortical reorganization starts “updating” the distribution of cortex regions.

A more annoying side of Phantom Limb Syndrome is that of Phantom Limb Pain. It is the arising of mild to extreme pain felt in the amputation area. In general, any sensation that the limb could have experienced prior to the amputation may be experienced again and amplify pain conditions. Usually, corresponding to cortical reorganization, phantom limb sensations usually disappear or decrease over time. Some medical treatments usually include heat application, relaxation techniques (massage, electrical nerve stimulation), neurostimulation techniques (such as spinal cord or deep brain stimulation) or surgery (in the case of scar tissues entangling a nerve).

sources: uno, due e tre