Plasticity through feedback

Most people know that the best and fastest way to learn something is to have excellent and instant feedback. In fact it is almost impossible, maybe always impossible, to learn something without any feedback. In general, we cannot control anything that does not provide feedback and we are much better at learning to control something if the feedback reaches consciousness.

Researchers at the University of Western Ontario (citation below) have used alpha wave feedback at enable changes in the brain and behavior.

our results indicate that at around 30 min after training, NFB (neurofeedback) induced a statistically significant up-regulation of functional connectivity within the dACC/MCC (dorsal anterior cingulate/mid-cingulate cortex) of the salience network in the experimental but not in the SHAM group. Hence utilizing fMRI and a placebo-control group we extend the findings of Ros et al. (2010) demonstrating that the adult cortex is sufficiently plastic that a mere half-hour of targeted volitional activity (i.e. NFB) is capable of intrinsically reconfiguring the brain’s functional activity to last above and beyond – and at least as long as – the time period of training itself.

This results in reductions in mind-wandering and increases in attention to a task – much as meditation does. There is a hope that this technique can be used to help some medical conditions that seem to be associated with abnormal alpha waves.

Here is the abstract:

Neurofeedback (NFB) involves a brain–computer interface that allows users to learn to voluntarily control their cortical oscillations, reflected in the electroencephalogram (EEG). Although NFB is being pioneered as a noninvasive tool for treating brain disorders, there is insufficient evidence on the mechanism of its impact on brain function. Furthermore, the dominant rhythm of the human brain is the alpha oscillation (8–12 Hz), yet its behavioral significance remains multifaceted and largely correlative. In this study with 34 healthy participants, we examined whether during the performance of an attentional task, the functional connectivity of distinct fMRI networks would be plastically altered after a 30-min session of voluntary reduction of alpha rhythm (n = 17) versus a sham-feedback condition (n = 17). We reveal that compared to sham-feedback, NFB induced an increase of connectivity within the salience network (dorsal anterior cingulate focus), which was detectable 30 min after termination of training. This increase in connectivity was negatively correlated with changes in ‘on-task’ mind-wandering as well as resting state alpha rhythm. Crucially, there was a causal dependence between alpha rhythm modulations during NFB and at subsequent resting state, not exhibited by the SHAM group. Our findings provide neurobehavioral evidence for a temporally direct, plastic impact of NFB on a key cognitive control network of the brain, suggesting a promising basis for its use to treat cognitive disorders under physiological conditions.

 

 

ResearchBlogging.org

Ros, T., Théberge, J., Frewen, P., Kluetsch, R., Densmore, M., Calhoun, V., & Lanius, R. (2012). Mind over chatter: Plastic up-regulation of the fMRI salience network directly after EEG neurofeedback NeuroImage DOI: 10.1016/j.neuroimage.2012.09.046

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Physicians should understand physiology

I am a skeptic when it comes to ghosts, aliens and near-death out of body experiences. That does not mean that I have a complete alternative explanation for what people have said happened to them. It just means that I find their explanation to be unconvincing.

My mother told me that she talked with my father after he died. I do not think she told anyone else for fear of being thought to believe in ghosts. She found it impossible to believe in ghosts. What she thought, and what I find found a reasonable explanation, was that there were times when she desperately need my father’s advice. She knew him so well that she actually could make a good guess at what he would tell her but it was hard to find that good guess. But after trying to solve a problem she had, before/as she fell asleep, she would hear my father’s voice and could discuss the problem with him. Over time this voice faded and she never thought that it was anything more than a conversation with herself.

Long ago in early societies there was often a believe that people actually traveled as spirits when they dreamed. We now believe that dreams are not actually happening but are an effect of brain maintenance processes. I would not expect anyone to believe that I was actually on a liner last night just because I dreamed about an old fashion ocean crossing. The dreams are real but not their narratives.

Nor do we believe, as early societies did that hallucinations (from drugs, starvation, illness etc.) were real happenings rather than weird products of an affected brain. Also there are explanations for being paralysed but awake from a dream – no need for demons or aliens sitting on your chest.

So why do some take near-death effects as real in a real sense of having happened outside the brain. I would expect someone who was aware of brain physiology and who had a near-death experience to explain it as what happens when the brain is lacking oxygen and/or undergoing many other unusual stresses. When the brain is in real trouble it registers – a tunnel, a bright light, a memory dump, a floating feeling (and, of course, some things that may be expected by the person’s religion/philosophy). Christian Jarrett gives a good post of how such things happen (here). So, I wonder, why is this treated differently to dreams and the like?

How can a neurophysician give us an explanation for his near-death experience involving the afterlife and consciousness that does not require the brain? (Proof of Heaven: A Neurosurgeon’s Journey into the Afterlife – Eben Alexander) With his medical knowledge, I would not want him treating any brain disease I might get.

Not a personality trait

There are people who are difficult or impossible to hypnotize. Many have thought this was because of their personality but this may not be true. ScienceDaily has an item (here) on the paper by Hieft and others, Functional Brain Basis of Hypnotizability in Archives of General Psychiatry.

The researchers examined 12 highly hypnotizable and 12 people with low hypnotizability with various scans, looking at three networks: the default network, the executive-control network and the salience network.

The findings, Spiegel said, were clear: Both groups had an active default-mode network, but highly hypnotizable participants showed greater co-activation between components of the executive-control network and the salience network. More specifically, in the brains of the highly hypnotizable group the left dorsolateral prefrontal cortex, an executive-control region of the brain, appeared to be activated in tandem with the dorsal anterior cingulate cortex, which is part of the salience network and plays a role in focusing of attention. By contrast, there was little functional connectivity between these two areas of the brain in those with low hypnotizability. Spiegel said he was pleased that he and his team found something so clear. “The brain is complicated, people are complicated, and it was surprising we were able to get such a clear signature,” he explained.

Hypnotizability is not due to personality variables but on cognitive style rooted in neural traits. Future work will look at how the networks interact under actual hypnosis.

An accurate ‘here’

ScienceDaily has an item (here) on a paper by Valerio and Taube, Path integration: how the head direction signal maintains and corrects spatial orientation in Nature Neuroscience. The research shows that there are two processes for correcting a navigation error, resetting and remapping.

There are two types of cell involved in following a path: the head direction cells in the thalamus that fire depending on the direction you are facing, and the place cells in the hippocampus that fire depending on where you are located.

Taube explains that the two populations — the head direction cells and the place cells — talk to one another. “They put that information together to give you an overall sense of ‘here,’ location wise and direction wise,” he says. “That is the first ingredient for being able to ask the question, ‘How am I going to get to point B if I am at point A?’ It is the starting point on the cognitive map.”

What happens when the animal finds it has made an error in navigation. That depends on the size of the error.

When the animal makes a small error and misses the target by a little, the cells will reset to their original setting, fixing on landmarks it can identify in its landscape. “We concluded that this was an active behavioral correction process, an adjustment in performance,” Taube says. “However, if the animal becomes disoriented and makes a large error in its quest for home, it will construct an entirely new cognitive map with a permanent shift in the directional firing pattern of the head direction cells.” This is the “remapping.”

I have long found a sense of direction very interesting. (This probably comes from growing up on the prairies where prominent landmarks are few and keeping track of my heading, with a sort of metaphorical compass, was very important.) I find being lost a very distinct and extremely nasty state of consciousness. It is a kind of loss of contact with the world – a little girl inside cries in panic, “I don’t know which way is north”. Perhaps this feeling is produced by knowing that the head cells need a permanent shift but not yet being able to make the right shift.

Hearing depends on the hand you are using

ScienceDaily reports on the press release from Georgetown University on a presentation at the annual meeting of the Society for Neuroscience 2012 (here). Peter Turkeltaub was the senior investigator. The research was looking at how the two hemispheres handle sound and the relationship between motor and perception processes.

They hid sounds in background noise and measured whether they were heard. Two changes were made: which hand was used to register hearing the sound and whether the sounds were rapidly changing (like consonants) or slowly changing (like syllables). When a subject was using their right hand, they heard the rapidly changing sounds more often than when they used their left hand, and vice versa for the slowly changing sounds.

Since the left hemisphere controls the right hand and vice versa, these results demonstrate that the two hemispheres specialize in different kinds of sounds — the left hemisphere likes rapidly changing sounds, such as consonants, and the right hemisphere likes slowly changing sounds, such as syllables or intonation,” Turkeltaub explains. “These results also demonstrate the interaction between motor systems and perception. It’s really pretty amazing. Imagine you’re waving an American flag while listening to one of the presidential candidates. The speech will actually sound slightly different to you depending on whether the flag is in your left hand or your right hand.

The result seems to fit with some theories about dyslexia (difference between hearing phonemes and syllables) and to that extent is not surprising. A little more surprising is the indication that a very general hemispheric dominance might be effected by which hand is in use at the time. Much more surprising is the idea that hemispheric dominance has an effect on the perceptions that rise to consciousness. There is still lots of surprises out there.

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What your heart tells you

The BPS Research Digest blog (here) featured a paper by Gu, Zhong and Page-Gould, Listen to Your Heart, When False Somatic Feedback Shapes Moral Behaviour.

It seems that when we make a decision, how moral it is can be affected by our heart rate. This does not rise to consciousness.

Gu and his colleagues think that a fast heart beat is interpreted by people as a sign they are stressed and that they should adhere to moral conventions as a way to escape that stress. The new finding is consistent with Antonio Damasio’s influential Somatic Marker hypothesis, which is based on the idea that bodily feedback guides our decisions, often at a non-conscious level.

It is interesting that when consciousness seems to be involved, the affect is lessened.

… the moral decision-making of people who are more mindful (for example, they agreed with statements like: “I perceive my feelings and emotions without having to react to them”) was unaffected by the false cardiac feedback. The researchers also found that telling participants that the financial game was a “decision-making” task led to immunity from the false heart feedback, relative to being told the game was an “intuitive task”.
This last result is particularly intriguing since we usually assume that thinking more deliberatively helps rein in the wild horses of our emotions, allowing us to behave more morally. The finding of Gu’s team suggests that in some circumstances at least, thinking more deliberately can undermine the influence of the heart, actually making it less likely that we’ll make a more moral decision.

Here is the paper’s abstract:

A pounding heart is a common symptom people experience when confronting moral dilemmas. The authors conducted 4 experiments using a false feedback paradigm to explore whether and when listening to a fast (vs. normal) heartbeat sound shaped ethical behavior. Study 1 found that perceived fast heartbeat increased volunteering for a just cause. Study 2 extended this effect to moral transgressions and showed that perceived fast heartbeat reduced lying for self-gain. Studies 3 and 4 explored the boundary conditions of this effect and found that perceived heartbeat had less influence on deception when people are mindful or approach the decision deliberatively. These findings suggest that the perceived physiological experience of fast heartbeats may signal greater distress in moral situations and hence motivate people to take the moral high road.

Dual focus is possible

ScienceDaily reports (here) on a paper by Niebergall, Khayat, Treue and Martinez-Trujillo, Multifocal Attention Filters Targets from Distracters within and beyond MT Neurons’ Receptive Field Boundaries.

What they show is the ability to split the ‘attentional spotlight’ in order to attend to multiple visual object without processing other objects between the objects of interest.

When we pay attention to an object, neurons responsible for this location in our field of view are more active then when they process unattended objects. But quite often we want to pay attention to multiple objects in different spatial positions, with interspersed irrelevant objects.

There are three theories of how this is done: either the focus is ‘zoomed out’ to cover all relevant objects even if this includes irrelevant ones; or, the focus is split into more than one focus; or, the focus switches back and forth between relevant objects.

In order to explain how such a complex ability is achieved, the neuroscientists measured the activity of individual neurons in areas of the brain involved in vision. They studied two rhesus macaques, which were trained in a visual attention task. The monkeys had learned to pay attention to two relevant objects on a screen, with an irrelevant object between them. The experiment showed, that the macaques’ neurons responded strongly to the two attended objects with only a weak response to the irrelevant stimulus in the middle. So the brain is able to spatially split visual attention and ignore the areas in between.

Here is the paper’s abstract:

Visual attention has been classically described as a spotlight that enhances the processing of a behaviorally relevant object. However, in many situations, humans and animals must simultaneously attend to several relevant objects separated by distracters. To account for this ability, various models of attention have been proposed including splitting of the attentional spotlight into multiple foci, zooming of the spotlight over a region of space, and switching of the spotlight among objects. We investigated this controversial issue by recording neuronal activity in visual area MT of two macaques while they attended to two translating objects that circumvented a third distracter object located inside the neurons’ receptive field. We found that when the attended objects passed through or nearby the receptive field, neuronal responses to the distracter were either decreased or remained unaltered. These results demonstrate that attention can split into multiple spotlights corresponding to relevant objects while filtering out interspersed distracters.

Play

Sam Wang and Sandra Aamodt have an article in Dana Cerebrum (here), Play, Stress, and the Learning Brain.

They define play.

First, play resembles a serious behavior, such as hunting or escaping, but is done by a young animal or is exaggerated, awkward, or otherwise altered. Second, play has no immediate survival purpose. It appears to be done for its own sake and is voluntary and pleasurable. Third, play occurs when an animal is not under stress and does not have something more pressing to do.

If that is play then it occurs among many animals: mammals, birds, some other vertebrates and even some invertebrates (octopus, squid, honeybee). This wide spread points to a very long history and suggests it serves a vital purpose. Another indication of usefulness is that play is fun; enjoyment is a sign of survival traits. Play is rewarded with dopamine. It is tailored to the lifestyle of the animal. Depending on the typical behavior of the animal there are three types of play. Playing with objects is typical of species that hunt, scavenge or eat a variety of foods. Locomotor play is usual in active animals who run, swim, fly, climb trees. Social play (fighting, chasing, wrestling) uses pretending in animals who have important social encounters. It is the species with the bigger brains for their body size who most engage in social play.

So play has an adaptive purpose or purposes. What would they be?

play is practice that prepares animals for the real activity later—when it matters. … In mammals, play is necessary for forming normal social connections. Rats and cats raised in social isolation become incompetent in dealing with others of their kind and typically react with aggression. In our species, abnormal play as children often presages dysfunction in adults. A notable feature of psychopaths is that their childhoods lacked in play. … Play also transmits culture. … Risk taking in children’s play may be an important developmental process. It tests boundaries and establishes what is safe and what is dangerous. … play also helps children learn what they like and don’t like.

Interesting, playing is a low stress activity (either play lowers stress or stress interferes with play). This is important for learning during play.

Play activates other brain signaling systems as well, including the neurotransmitter

norepinephrine. … Norepinephrine is also involved in rousing us to attention and action, but by acting as a neurotransmitter. Norepinephrine facilitates learning mechanisms at synapses as well. In some neurons, norepinephrine improves brain plasticity, such that change becomes possible when this chemical is present in elevated amounts. The same is true for dopamine, which accounts for how reward leads to long-term changes to make us want more—neural plasticity mechanisms are strongly facilitated when reward occurs. … Though real-life stressors trigger the release of both epinephrine and cortisol, play does not increase cortisol. Cortisol is a stress hormone that helps us in genuinely dangerous situations by redirecting resources to the most urgent needs, such as repairing a wound or fighting an infection.

For humans, play continues into adulthood.

work in adult life is often most effective when it resembles play. Indeed, total immersion in an activity often indicates that the activity is intensely enjoyable; this is the concept of flow, or what athletes call being in the zone. Flow occurs during active experiences that require concentration but are also highly practiced, where the goals and boundaries are clear but leave room for creativity. This describes many adult hobbies, from skiing to music, as well as careers like surgery and computer programming. Such immersion can make solving a great challenge as easy as child’s play.

And not just humans play as adults. Dogs do and they have a special signal to commence play so that their actions are not misunderstood. It is a similar signal in many animals and young of different species have been seen playing together.

What has this to do with consciousness? It seems to me that play is like a type of consciousness – a way of experiencing the world that can be turned on and off. We are able to experience a low tension, enjoyable, somewhat pretend world in which we actively experiment, discover and learn.

Three ways to build a brain

Only mammals have a neocortex. But we know from behaviour that birds and reptiles think a lot like mammals. They must have structures and processes similarly to a neocortex.

ScienceDaily has a report (here) on research by Dugas-Ford and others in a PNAS paper, Cell-type homologies and the origins of the neocortex. The group looked for neurons similar to those in the neocortex in birds. This supports a 50 year old hypothesis.

Both the mammalian neocortex and a structure in the bird brain called the dorsal ventricular ridge (DVR) originate from an embryonic region called the telencephalon. But the two regions mature into very different shapes, with the neocortex made up of six distinct cortical layers while the DVR contains large clusters of neurons called nuclei. … in the 1960s, neuroscientist Harvey Karten studied the neural inputs and outputs of the DVR, finding that they were remarkably similar to the pathways traveling to and from the neocortex in mammals. As a result, he proposed that the DVR performs a similar function to the neocortex despite its dramatically different anatomy.

Dugas-Ford, Ragsdale and co-author Joanna Rowell decided to test Karten’s hypothesis by using recently discovered sets of molecular markers that can identify specific layers of mammalian cortex: the layer 4 “input” neurons or layer 5 “output” neurons. The researchers then looked for whether these marker genes were expressed in the DVR nuclei.

They found the level 4 and 5 markers in chicken and zebra finch. But instead for being in layers as in the neocortex, in the DVR the marked cells are in distinct nuclei. They looked at turtles as well and found the level 4 and 5 markers but this time in a single layer on the dorsal cortex. There may be advantages and disadvantages to the different structures using these neurons.

The complex language and tool-use of some bird species suggests that the nuclear organization of this pathway is also capable of supporting advanced functions — and even may offer advantages over the mammalian brain.

“If you wanted to have a special nuclear processing center in Broca’s area to carry out language processing, you can’t do that in a mammal,” Ragsdale said. “But in a bird they have these special nuclei that are involved in vocalization. It’s as if you have additional flexibility: You can have shorter circuits, longer circuits, you can have specialized processing centers.”

We can look forward to this putative homology being productive in studying the embryonic development of the brain and in understanding the mechanisms of neocortex activity.

 

Cherished Principle

Lets deal with reductionism. In some quarters it seems to have a bad name. To me it is one of the corner stones of the confidence in science.

 

Conventionally, we have the physical sciences, mainly physics and chemistry, that examine the basics of matter and energy, space and time. The findings should be universally applicable to everything except spooking spiritual non-material stuff. On top of this we have (my personal name) the historic sciences, mainly geology, biology and astronomy, that examine how things came to be the way they are at any time and place. They use the ‘laws’ and ‘theories’ of the physical sciences as the foundations for their own ‘theories’. In this sense the historical sciences’ theories can be reduced to those of physics and chemistry. This does not mean that a geologist is going to explain volcanos in terms of protons and electrons – but they know that if they worked the years it would take, they could do it. Sciences are looking for foundational theories that cover their area. So physics has quantum theory and the theory of relativity (which they want to connect in one theory). Plate tectonic theory is almost central to geology; biology rests largely on the theory of evolution. Each of these sciences has its specialty areas, like molecular biology with their own theories; molecular biology can be reduced to biology and chemistry. These theories are convincing because of the experimental evidence and because they can be reduced to physical sciences.

 

I know there are other sciences such as the applied sciences like medicine that lean on other sciences. And there are non-sciences that science uses as tools such as mathematics. Nothing is as simple as this little picture implies. I am not trying to draw a picture of the sciences but of the principal of reductionism.

 

Reductionism does not mean taking the world apart and not putting it back together – things are not left thrown about on the floor. It is not the opposite of holistic thinking – science very often looks at the big picture. Reductionism is the insurance policy that thought has not flown away from the solid ground of the physical world and that different as the various sciences are, they are not incompatible.

 

This is why the phrase ‘emerging properties’ bothers me. It is one thing to say, “here is the evidence but it has not yet been reconciled with some other parts of science.” It is often an honest statement of the state of affairs. But to say that something is an emerging property is not clear. It is used often as an explanation although it explains nothing but it does imply that reduction might be impossible. Sometimes it seems to mean that the evidence appears to show a material situation but I would like to leave open a non-material situation. Or vice versa, it looks non-material but I would like to leave open the possibility that it is material. It is sitting of the fence be refusing to say that the state of reduction actually is in this case.

 

There is another idea that bothers me. It is that there is a material world with no dualism or magic non-material stuff ; BUT, there are two ways to describe it that are not connected by reduction. What? There are psychological/mental explanations and scientific/biological explanations of the same things. It is not the reality that is dualist but the description of reality. This is like saying that psychology is not a science and never will be. That is not what many psychologists want.

 

I, for one, cherish reduction as an ideal in science. In Christof Koch book, Consciousness: Confessions of a Romantic Reductionist, he says he is a reductionist because, “I seek quantitative explanations for consciousness in the ceaseless and ever-varied activity of billions of tiny nerve cells, each with their tens of thousands of synapses; romantic, because of my insistence that the universe has contrails of meaning that can be deciphered in the sky about us and deep within us”

 

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