by Janet Kwazniak
Dijksterhuis and Nordgren put forward a theory of unconscious thought. They propose that there are two types of thought process: conscious and unconscious. “CT (conscious thought) refers to object-relevant or task-relevant cognitive or affective thought processes that occur while the object or task is the focus of one’s conscious attention, whereas UT (unconscious thought) refers to object-relevant or task-relevant cognitive or affective thought processes that occur while conscious attention is directed elsewhere.’’
Like Kahneman’s System 1 and System 2 thought there is no implication here that there is purely conscious thought with no unconscious components but only that conscious awareness is part of the process. I prefer the System name as it avoids the possible interpretation that there might be purely conscious thought. System 1 is like UT and is characterized as: autonomous, fast, effortless, hidden/unconscious, simultaneous/parallel/complex. System 2 is like CT: deliberate, slow, effortful, conscious, serial/logical/simple. The most telling difference is whether working memory is used; working memory restricts the number of items that can be manipulated in thought to about 7 or less at a time and introduces the conscious awareness of the working memory. It is often viewed as a difference between calculation and estimation, or between explicit and implicit knowledge.
The way these two processes are compared is to set out a problem and then compare the results after one of three activities: the subjects can consciously think about the problem for a certain length of time; the subjects can spend the same amount of time doing something that completely engages their consciousness; or they can be giving no time at all and asked for the answer immediately after the problem is presented. It has been found that with complex problems with many ingredients, that System 1/UT gives more quality results then System 2/CT and both are better than immediate answers.
A recent paper by Li, Zhu and Yang looks at another comparison of the two ways of thinking. (citation below)
According to unconscious thought theory (UTT), unconscious thought is more adept at complex decision-making than is conscious thought. Related research has mainly focused on the complexity of decision-making tasks as determined by the amount of information provided. However, the complexity of the rules generating this information also influences decision making. Therefore, we examined whether unconscious thought facilitates the detection of rules during a complex decision-making task. Participants were presented with two types of letter strings. One type matched a grammatical rule, while the other did not. Participants were then divided into three groups according to whether they made decisions using conscious thought, unconscious thought, or immediate decision. The results demonstrated that the unconscious thought group was more accurate in identifying letter strings that conformed to the grammatical rule than were the conscious thought and immediate decision groups. Moreover, performance of the conscious thought and immediate decision groups was similar. We conclude that unconscious thought facilitates the detection of complex rules, which is consistent with UTT.
It is a characteristic of System 2/CT that it is used to rigorously follow rules to calculate a result. However there is a difference between following a rule and discovering one. This rule discovery activity may be the same as implicit learning. “Mealor and Dienes (2012) combined UT and implicit learning research paradigms to investigate the impact of UT on artificial grammar learning. A classic implicit learning paradigm consists of two stages: training and testing. ” The UT group had better results but they categorized the process as random selection. The current paper shows that the UT group can find the grammatical rules illustrated in the training and then identify grammatical as opposed to ungrammatical strings. System 1/UT is better at uncovering rules and of identifying examples that break the rules. This does not seem to be a rigorous following of rules as in System 2 but more a statistical tendency or a stereotypical categorization of the nature of implicit learning.
It is important to be clear that System 2 or CT is thought that has a conscious component and it does not imply that the thought is conducted ‘in’ consciousness. We are aware of the steps in a train of thought, but not aware of the process, they are hidden.
Li, J., Zhu, Y., & Yang, Y. (2014). The Merits of Unconscious Thought in Rule Detection PLoS ONE, 9 (8) DOI: 10.1371/journal.pone.010655
An Intriguing Take on Consciousness -
by Deric Bownds
A recent review by Aaron Schurger in Science Magazine pointed me to Michael Graziano’s 2013 book “Consciousness and the Social Brain”, which I immediately downloaded, read, and abstracted. Very engaging and clear writing (although I am dumbfounded that he makes no reference to Thomas Metzinger’s work and ‘ego tunnel’ model, which has common elements with his own.) In Graziano’s theory awareness is information, the brain’s simplified, schematic model of the complicated, data-handling process of attention. A brain can use the construct of awareness to model its own attentional state or to model someone else’s attentional state. An extract from Schurger’s review:
In Consciousness and the Social Brain, Michael Graziano argues that consciousness is a perceptual construct—the brain attributes it to other people in much the same way that the brain attributes speech to the ventriloquist’s puppet. To clarify, imagine being greeted by a very lifelike android version of your best friend with a prerecorded behavioral program that had you genuinely fooled for a few minutes. From your perspective, for those minutes, the android was endowed with consciousness. Thus there need be no truth or falsity to the statement “My friend standing before me is conscious.” Your brain decides that the android–best friend standing in front of you is conscious, and that is what you perceive to be true.
According to Graziano’s “attention schema” theory, our own consciousness is also a perceptual construct—a unique one that emerges when the brain applies the same perceptual attribution recursively to itself. We attribute consciousness to others as part of our perceptual model of what they are paying attention to (an inference particularly useful for predicting their behavior). This model describes the process of attention as a mysterious something extra in the brains of beings that are selectively processing information that guides their behavior. When the brain applies the model to itself, “I” become endowed with this extra something as well—although, as with the android, it was never there in the first place.
According to the theory, consciousness is to attention what the body schema is to the body: it is the brain’s perceptual description of its own process of attention. The two phenomena are thus locked “in a positive feedback loop,” which explains the tight connection between attention and consciousness. In essence, consciousness is a descriptive story about a real physical phenomenon (attention). The ink in which the story is written (neural activity) is real, and the physical phenomenon that the story is “about” (attention) is real. But, like the talking puppet, the story itself need not be real. We say that we have consciousness, and that it seems irreducible to physical phenomena, because that is how the brain describes the process of attention (in ourselves and in others): as something ineffable.
I’ll also give you a clip from my abstracting of the book:
The heart of the theory is that awareness is a schematized, descriptive model of attention. The model is not perfectly accurate, but it is good enough to be useful. It is a rich information set, as rich as a sensory representation. It can be bound to a representation of an object as though it were another sensory attribute like color or motion….the purpose of a model in the brain is to be useful in interacting with the world, not to be accurate.
The body schema and the attention schema may share more than a formal similarity. They may partially overlap. The body schema is an internal model— an organized set of information that represents the shape, structure, and movement of the body, that distinguishes between objects belonging to the body and objects that are foreign.
In the present theory, the attention schema is similar to the body schema. Rather than representing one’s physical body, it models a different aspect of oneself, also a complex dynamical system, the process of attention— the process by which some signals in the brain become enhanced at the expense of others. It is a predictive model of attention, its dynamics, its essential meaning, its potential impact on behavior, what it can and can’t do, what affects it, and how. It is a simulation. The quirky way that attention shifts from place to place, from item to item, its fluctuating intensity, its spatial and temporal dynamics— all of these aspects are incorporated into the model.
Consciousness is constructed through a discrete set of activity spaces. -
by Deric Bownds
This fascinating work by Hudson et al. shows that as the brain recovers consciousness from a perturbation such as anesthesia, it does not follows a steady and monotonic path towards consciousness, but rather passes through several discrete activity states. They performed a principal component analysis on local field potentials recorded with electrodes inserted into rat anterior cingulate and retrosplenial cortices and the intralaminar thalamus:
It is not clear how, after a large perturbation, the brain explores the vast space of potential neuronal activity states to recover those compatible with consciousness. Here, we analyze recovery from pharmacologically induced coma to show that neuronal activity en route to consciousness is confined to a low-dimensional subspace. In this subspace, neuronal activity forms discrete metastable states persistent on the scale of minutes. The network of transitions that links these metastable states is structured such that some states form hubs that connect groups of otherwise disconnected states. Although many paths through the network are possible, to ultimately enter the activity state compatible with consciousness, the brain must first pass through these hubs in an orderly fashion. This organization of metastable states, along with dramatic dimensionality reduction, significantly simplifies the task of sampling the parameter space to recover the state consistent with wakefulness on a physiologically relevant timescale.
Potential On/Off Switch to Conscious Awareness Found -
Brief summary by Helen Thomson
For the first time, researchers have switched off consciousness by electrically stimulating a single brain area.
Although only tested in one person [who was also missing a section of her hippocampus], the discovery suggests that a single area – the claustrum – might be integral to combining disparate brain activity into a seamless package of thoughts, sensations and emotions. It takes us a step closer to answering a problem that has confounded scientists and philosophers for millennia – namely how our conscious awareness arises.
Many theories abound but most agree that consciousness has to involve the integration of activity from several brain networks, allowing us to perceive our surroundings as one single unifying experience rather than isolated sensory perceptions.
One proponent of this idea was Francis Crick, a pioneering neuroscientist who earlier in his career had identified the structure of DNA. Just days before he died in July 2004, Crick was working on a paper that suggested our consciousness needs something akin to an orchestra conductor to bind all of our different external and internal perceptions together.
With his colleague Christof Koch, at the Allen Institute for Brain Science in Seattle, he hypothesized that this conductor would need to rapidly integrate information across distinct regions of the brain and bind together information arriving at different times. For example, information about the smell and colour of a rose, its name, and a memory of its relevance, can be bound into one conscious experience of being handed a rose on Valentine’s day.
The pair suggested that the claustrum – a thin, sheet-like structure that lies hidden deep inside the brain – is perfectly suited to this job (Philosophical Transactions of The Royal Society B, doi.org/djjw5m).
It now looks as if Crick and Koch were on to something. In a study published last week, Mohamad Koubeissi at the George Washington University in Washington DC and his colleagues describe how they managed to switch a woman’s consciousness off and on by stimulating her claustrum. The woman has epilepsy so the team were using deep brain electrodes to record signals from different brain regions to work out where her seizures originate. One electrode was positioned next to the claustrum, an area that had never been stimulated before.
When the team zapped the area with high frequency electrical impulses, the woman lost consciousness. She stopped reading and stared blankly into space, she didn’t respond to auditory or visual commands and her breathing slowed. As soon as the stimulation stopped, she immediately regained consciousness with no memory of the event. The same thing happened every time the area was stimulated during two days of experiments (Epilepsy and Behavior, doi.org/tgn).
To confirm that they were affecting the woman’s consciousness rather than just her ability to speak or move, the team asked her to repeat the word “house” or snap her fingers before the stimulation began. If the stimulation was disrupting a brain region responsible for movement or language she would have stopped moving or talking almost immediately. Instead, she gradually spoke more quietly or moved less and less until she drifted into unconsciousness. Since there was no sign of epileptic brain activity during or after the stimulation, the team is sure that it wasn’t a side effect of a seizure.
Counter-intuitively, Koubeissi’s team found that the woman’s loss of consciousness was associated with increased synchrony of electrical activity, or brainwaves, in the frontal and parietal regions of the brain that participate in conscious awareness. Although different areas of the brain are thought to synchronise activity to bind different aspects of an experience together, too much synchronisation seems to be bad. The brain can’t distinguish one aspect from another, stopping a cohesive experience emerging.
Anil Seth, who studies consciousness at the University of Sussex, UK, warns that we have to be cautious when interpreting behaviour from a single case study. The woman was missing part of her hippocampus, which was removed to treat her epilepsy, so she doesn’t represent a “normal” brain, he says.
However, he points out that the interesting thing about this study is that the person was still awake. “Normally when we look at conscious states we are looking at awake versus sleep, or coma versus vegetative state, or anaesthesia.” Most of these involve changes of wakefulness as well as consciousness but not this time, says Seth. “So even though it’s a single case study, it’s potentially quite informative about what’s happening when you selectively modulate consciousness alone.”
Here’s the abstract:
The neural mechanisms that underlie consciousness are not fully understood. We describe a region in the human brain where electrical stimulation reproducibly disrupted consciousness. A 54-year-old woman with intractable epilepsy underwent depth electrode implantation and electrical stimulation mapping. The electrode whose stimulation disrupted consciousness was between the left claustrum and anterior-dorsal insula. Stimulation of electrodes within 5 mm did not affect consciousness. We studied the interdependencies among depth recording signals as a function of time by nonlinear regression analysis (h2coefficient) during stimulations that altered consciousness and stimulations of the same electrode at lower current intensities that were asymptomatic. Stimulation of the claustral electrode reproducibly resulted in a complete arrest of volitional behavior, unresponsiveness, and amnesia without negative motor symptoms or mere aphasia. The disruption of consciousness did not outlast the stimulation and occurred without any epileptiform discharges. We found a significant increase in correlation for interactions affecting medial parietal and posterior frontal channels during stimulations that disrupted consciousness compared with those that did not. Our findings suggest that the left claustrum/anterior insula is an important part of a network that subserves consciousness and that disruption of consciousness is related to increased EEG signal synchrony within frontal–parietal networks.
New study discovers biological basis for magic mushroom ‘mind expansion’
Psychedelic drugs such as LSD and magic mushrooms can profoundly alter the way we experience the world but little is known about what physically happens in the brain. New research, published in Human Brain Mapping, has examined the brain effects of the psychedelic chemical in magic mushrooms, called psilocybin, using data from brain scans of volunteers who had been injected with the drug.
The study found that under psilocybin, activity in the more primitive brain network linked to emotional thinking became more pronounced, with several different areas in this network - such as the hippocampus and anterior cingulate cortex - active at the same time. This pattern of activity is similar to the pattern observed in people who are dreaming. Conversely, volunteers who had taken psilocybin had more disjointed and uncoordinated activity in the brain network that is linked to high-level thinking, including self-consciousness.
Psychedelic drugs are unique among other psychoactive chemicals in that users often describe ‘expanded consciousness,’ including enhanced associations, vivid imagination and dream-like states. To explore the biological basis for this experience, researchers analysed brain imaging data from 15 volunteers who were given psilocybin intravenously while they lay in a functional magnetic resonance imaging (fMRI) scanner. Volunteers were scanned under the influence of psilocybin and when they had been injected with a placebo.
“What we have done in this research is begin to identify the biological basis of the reported mind expansion associated with psychedelic drugs,” said Dr Robin Carhart-Harris from the Department of Medicine, Imperial College London. “I was fascinated to see similarities between the pattern of brain activity in a psychedelic state and the pattern of brain activity during dream sleep, especially as both involve the primitive areas of the brain linked to emotions and memory. People often describe taking psilocybin as producing a dream-like state and our findings have, for the first time, provided a physical representation for the experience in the brain.”
The new study examined variation in the amplitude of fluctuations in what is called the blood-oxygen level dependent (BOLD) signal, which tracks activity levels in the brain. This revealed that activity in important brain networks linked to high-level thinking in humans becomes unsynchronised and disorganised under psilocybin. One particular network that was especially affected plays a central role in the brain, essentially ‘holding it all together’, and is linked to our sense of self.
In comparison, activity in the different areas of a more primitive brain network became more synchronised under the drug, indicating they were working in a more co-ordinated, ‘louder’ fashion. The network involves areas of the hippocampus, associated with memory and emotion, and the anterior cingulate cortex which is related to states of arousal.
Lead author Dr Enzo Tagliazucchi from Goethe University, Germany said: “A good way to understand how the brain works is to perturb the system in a marked and novel way. Psychedelic drugs do precisely this and so are powerful tools for exploring what happens in the brain when consciousness is profoundly altered. It is the first time we have used these methods to look at brain imaging data and it has given some fascinating insight into how psychedelic drugs expand the mind. It really provides a window through which to study the doors of perception.”
Dr. Carhart-Harris added: “Learning about the mechanisms that underlie what happens under the influence of psychedelic drugs can also help to understand their possible uses. We are currently studying the effect of LSD on creative thinking and we will also be looking at the possibility that psilocybin may help alleviate symptoms of depression by allowing patients to change their rigidly pessimistic patterns of thinking. Psychedelics were used for therapeutic purposes in the 1950s and 1960s but now we are finally beginning to understand their action in the brain and how this can inform how to put them to good use.”
The data was originally collected at Imperial College London in 2012 by a research group led by Dr Carhart-Harris and Professor David Nutt from the Department of Medicine, Imperial College London. Initial results revealed a variety of changes in the brain associated with drug intake. To explore the data further Dr. Carhart-Harris recruited specialists in the mathematical modelling of brain networks, Professor Dante Chialvo and Dr Enzo Tagliazucchi to investigate how psilocybin alters brain activity to produce its unusual psychological effects.
As part of the new study, the researchers applied a measure called entropy. This was originally developed by physicists to quantify lost energy in mechanical systems, such as a steam engine, but entropy can also be used to measure the range or randomness of a system. For the first time, researchers computed the level of entropy for different networks in the brain during the psychedelic state. This revealed a remarkable increase in entropy in the more primitive network, indicating there was an increased number of patterns of activity that were possible under the influence of psilocybin. It seemed the volunteers had a much larger range of potential brain states that were available to them, which may be the biophysical counterpart of ‘mind expansion’ reported by users of psychedelic drugs.
Previous research has suggested that there may be an optimal number of dynamic networks active in the brain, neither too many nor too few. This may provide evolutionary advantages in terms of optimising the balance between the stability and flexibility of consciousness. The mind works best at a critical point when there is a balance between order and disorder and the brain maintains this optimal number of networks. However, when the number goes above this point, the mind tips into a more chaotic regime where there are more networks available than normal. Collectively, the present results suggest that psilocybin can manipulate this critical operating point.
Tracking Conscious Perception in Real-Time With fMRI? -
What if it were possible to measure your conscious experience, in real time, using a brain scanner? Neuroscientists Christoph Reichert and colleagues report that they have done just this, using fMRI – although in a limited fashion.
Their research has just been published in Frontiers in Neuroscience:Online tracking of the contents of conscious perception using real-time fMRI
The particular conscious perception that Reichert et al tracked was an example of a bistable visual percept. These are images (or, in this case, a movie) that can be seen in one of two ways. If you look at a bistable image for some time, it seems to ‘switch’ repeatedly between one state and the other – even though the image is unchanged. The best known example is theNecker Cube which can be seen as either pointing ‘left’ or ‘right’:
Because the ‘switching’ of a bistable percept is a purely subjective phenomenon, having nothing to do with objective changes in the image, it’s a useful way to study conscious perception. Previous neuroimaging studies have found differences in brain activation associated with the different states of bistable percepts, but Reichert et al decided to investigate if it were possible to measure these in real time.
The percept they used was a movie in which part of a simple line drawing was shown; in each frame a different part of the drawing was displayed, as if the drawing were moving left and right behind a grey screen with a vertical slit in it. The ‘slit’ is depicted below as an orange box, along with the whole drawing, but note that neither of these things were actually shown. What actually appeared on the screen was just a slice of the drawing, as shown on the right below. This slice was constantly changing (on a loop).
When viewing this movie, Reichert et al say, ones perception spontaneously alternates between ‘two curved lines moving up and down’ and ‘one object moving left and right, behind a screen’. In other words, sometimes the brain ‘fills in’ the whole figure, but sometimes it doesn’t, leaving the isolated lines. The alternations between the two impressions happen unpredictably, with anything from 5 to 50 seconds between each ‘flip’.
So, could brain activity be used to work out which perception someone is seeing at any given time? Yes indeed, say Reichert et al. They say that both the ‘filled-in’ and ‘isolated’ versions of the percept are associated with different patterns of neural activity and that, based on these characteristic patterns, the ‘active’ percept can be detected, in ‘real time’ (i.e. with about 10 seconds lag, due to the way fMRI works) with 75-80% accuracy. Just flipping a coin would get about 50% right so this is substantially better than chance.
The design of the study was somewhat complex with several different comparisons but from what I can see, the methods were appropriate.
Perhaps the most striking finding was that the real-time algorithm generalized across individuals (in a leave-one-subject-out validation). So it would be possible to put someone in the scanner, someone who’d not been scanned before, and tell what they were perceiving with no need for calibration. This is pretty impressive, and quite rare for a ‘mind reading’ fMRI algorithm. However, it’s important to remember that this study was only about one very specific aspect of perception.
It’s really pretty amazing when you stop to think about it. Previously, only one person in all the world could possibly know which percept I was experiencing – me. I could tell you about my experience, but as it remainedmy experience, you’d have to take my word for it. You’d have no way to check.
Now, thanks to Reichert et al, you do have a way. The veil of ignorance between I and thou is not, quite, impenetrable after all.
Reichert C, Fendrich R, Bernarding J, Tempelmann C, Hinrichs H, & Rieger JW (2014). Online tracking of the contents of conscious perception using real-time fMRI. Frontiers in neuroscience, 8 PMID: 24904260
Brain activity underlying subjective awareness -
Hill and He devise and interesting paradigm to distinguish brain activities directly contributing to conscious perception from brain activities that precede or follow it. They do this by examining trial by trial objective performance, subjective awareness, and the confidence level of subjective awareness. They find that widely distributed slow cortical potentials in the < 4 Hz (delta) range - i.e. brain activity waves taking longer than a quarter of a second - correlate with subjective awareness, even after the effects of objective performance and confidence (contributed by more transient brain activity) were both removed. Here is their abstract:
Despite intense recent research, the neural correlates of conscious visual perception remain elusive. The most established paradigm for studying brain mechanisms underlying conscious perception is to keep the physical sensory inputs constant and identify brain activities that correlate with the changing content of conscious awareness. However, such a contrast based on conscious content alone would not only reveal brain activities directly contributing to conscious perception, but also include brain activities that precede or follow it. To address this issue, we devised a paradigm whereby we collected, trial-by-trial, measures of objective performance, subjective awareness, and the confidence level of subjective awareness. Using magnetoencephalography recordings in healthy human volunteers, we dissociated brain activities underlying these different cognitive phenomena. Our results provide strong evidence that widely distributed slow cortical potentials (SCPs) correlate with subjective awareness, even after the effects of objective performance and confidence were both removed. The SCP correlate of conscious perception manifests strongly in its waveform, phase, and power. In contrast, objective performance and confidence were both contributed by relatively transient brain activity. These results shed new light on the brain mechanisms of conscious, unconscious, and metacognitive processing.
Scientists Induce Lucid Dreaming With Electrical Stimulation -
by Stephen Luntz
Out of body, out of mind. -
by Deric Bownds
Bergouignan et al. do a neat experiment in which they test how well study participants remember a presentation when they experience being in their own bodies versus out of their bodies looking at the presentation from another perspective. They find that if an event is experienced from an ‘out-of-body’ perspective, it is remembered less well and its recall does not induce the usual pattern of hippocampal activation. This means that hippocampus-based episodic memory depends on the perception of the world from within our own bodies, and that a dissociative experience during encoding blocks the memory-forming mechanism. Here is their abstract, followed by a description of how they set up out of body experience.
Theoretical models have suggested an association between the ongoing experience of the world from the perspective of one’s own body and hippocampus-based episodic memory. This link has been supported by clinical reports of long-term episodic memory impairments in psychiatric conditions with dissociative symptoms, in which individuals feel detached from themselves as if having an out-of-body experience. Here, we introduce an experimental approach to examine the necessary role of perceiving the world from the perspective of one’s own body for the successful episodic encoding of real-life events. While participants were involved in a social interaction, an out-of-body illusion was elicited, in which the sense of bodily self was displaced from the real body to the other end of the testing room. This condition was compared with a well-matched in-body illusion condition, in which the sense of bodily self was colocalized with the real body. In separate recall sessions, performed ∼1 wk later, we assessed the participants’ episodic memory of these events. The results revealed an episodic recollection deficit for events encoded out-of-body compared with in-body. Functional magnetic resonance imaging indicated that this impairment was specifically associated with activity changes in the posterior hippocampus. Collectively, these findings show that efficient hippocampus-based episodic-memory encoding requires a first-person perspective of the natural spatial relationship between the body and the world. Our observations have important implications for theoretical models of episodic memory, neurocognitive models of self, embodied cognition, and clinical research into memory deficits in psychiatric disorders.
During the life events to be remembered (“encoding sessions”), the participants sat in a chair and wore a set of head-mounted displays (HMDs) and earphones, which were connected to two closed-circuit television (CCTV) cameras and to an advanced “dummy-head microphone,” respectively. This technology enabled the participants to see and hear the testing room in three dimensions from the perspective of the cameras mounted with the dummy head microphones. The cameras were either placed immediately above and behind the actual head of the participant, creating an experience of the room from the perspective of the real body (in-body condition), or the cameras were placed 2 m in front or to the side of the participant, thus making the participants experience the room and the individuals in it as an observer outside of their real body (out-of-body condition). To induce the strong illusion of being fully located in one of these two locations and sensing an illusory body in this place, we repetitively moved a rod toward a location below the cameras and synchronously touched the participant’s chest for a period of 70 s, which provided congruent multisensory stimulation to elicit illusory perceptions. The illusion was maintained for 5 min, during which the ecologically valid life events took place (see next section); throughout this period, the participant received spatially congruent visual and auditory information via the synchronized HMDs and dummy head microphones, which further facilitated the maintenance of the illusion.
The Power of Conscious Intention Proven? -
A neuroscience paper published before Christmas draw my eye with the expansive title: “How Thoughts Give Rise to Action“
Subtitled “Conscious Motor Intention Increases the Excitability of Target-Specific Motor Circuits”, the article’s abstract was no less bold, concluding that:
These results indicate that conscious intentions govern motor function… until today, it was unclear whether conscious motor intention exists prior to movement, or whether the brain constructs such an intention after movement initiation.
The authors, Zschorlich and Köhling of the University of Rostock, Germany, are weighing into a long-standing debate in philosophy, psychology, and neuroscience, concerning the role of consciousness in controlling our actions.
To simplify, one school of thought holds that (at least some of the time), our intentions or plans control our actions. Many people would say that this is what common sense teaches us as well.
But there’s an alternative view, in which our consciously-experienced intentions are not causes of our actions but are actually products of them, being generated after the action has already begun. This view is certainly counterintuitive, and many find it disturbing as it seems to undermine ‘free will’.
That’s the background. Zschorlich and Köhling say that they’ve demonstrated that conscious intentions do exist, prior to motor actions, and that these intentions are accompanied by particular changes in brain activity. They claim to have done this using transcranial magnetic stimulation (TMS), a way of causing a localized modulation of brain electrical activity.
TMS of the motor cortex can cause muscle twitches, because this part of the brain controls our muscles. In 14 healthy volunteers, Zschorlich and Köhling aimed TMS at the area responsible for controlling movements of the left arm. Importantly, they adjusted the strength of the pulse so that it was only just strong enough to cause a tiny twitch (as measured using electrodes overthe muscles of the left wrist themselves).
Remarkably, however, they found that if people were ‘consciously intending’ to flex their wrist, the same weak TMS pulse prompted a strong flexion response. Whereas if the volunteer was intending to extend their wrist, the very same pulse caused an extension movement.
Here’s an example from one representative subject, showing the differences in muscle activity in the flexing (FCR) and extending (ECR) muscles of the wrist following the TMS pulses:
The authors hypothesize that the brain’s ‘intention network’ prepares desired actions by increasing the excitability of the cells in the motor cortex that can produce the movement intended. On this view, a weak TMS pulse provides just enough extra activation to trigger those pre-excited cells into firing, while being too weak to activate cells that govern other movements.
It’s an interesting model and these are striking results, from a beautifully simple experiment. My only concern is that it might be too simple. There was no control condition for the TMS: every TMS pulse was real.
It would have been better to have used a control, either a ‘sham’ pulse, or a real TMS pulse over a different part of the brain. I say that because – unless I’m missing something here – we don’t actually know that the TMS pulse was triggering the wrist movements. The volunteers got to trigger the TMS themselves:
Volunteers were asked to develop an intention […] and to trigger the TMS with the right index finger if the urge to move was greatest before any overt motor output at the wrist.
As far as I can see, volunteers could simply have been pressing the TMS button and then moving their wrist of their own accord. Ironically, they might not have consciously intended to do this; they might have really believed that their movements were being externally triggered (by the TMS) even though they themselves were generating them. This can happen: it’s called the ideomotor phenomenon, and is probably the explanation for why people believe in ‘dowsing’ amongst other things.
All we know for sure, as I understand it, is that 1. their right hand pushed a button, 2. TMS happened, and 3. their left wrist moved. We don’t know that 2 caused 3. A control TMS condition would have allowed us to know whether the TMS was really involved – and, perhaps, whether conscious intention or unconscious ideomotor acts were governing those errant wrists.
Zschorlich VR, & Köhling R (2013). How thoughts give rise to action – conscious motor intention increases the excitability of target-specific motor circuits. PloS ONE, 8 (12) PMID: 24386291
Famed amnesia case, K.C. died last week. Having lost both hippocampuses after a motorcycle accident, he was somehow able to hold on to some memories, though “devoid of all context and emotion”… and his identity.
That’s actually a common theme in the neuroscience of accidents. It’s easy to see the victims of brain damage as reduced or diminished, and they are in some ways. But much of what they feel from moment to moment is exactly what you or I feel, and there’s almost nothing short of death that can make you forget who you are. Amid all the fascinating injuries in neuroscience history, you’ll come across a lot of tales of woe and heartbreak. But there’s an amazing amount of resiliency in the brain, too. [via]
Clash of 'grand theories' of consciousness?? -
by Deric Bownds
In what strikes me in the most unlikely venue, The Huffington Post, new age guru (also savvy businessman and marketer) Deepak Chopra offers what seems to an equivalent to the “teach the controversy” arguments of the creationists. The title “‘Collision Course’ in the Science of Consciousness: Grand Theories to Clash at Tucson Conference” suggests that there are two grand theories when in fact there are not. Massive evidence supports the idea that consciousness is accounted for by complex interactions between nerve cells, and Chopra does a nice summary of two central researchers taking this approach:
Christof Koch now teams with psychiatrist and neuroscientist Giulio Tononi in applying principles of integrated information, computation and complexity to the brain’s neuronal and network-level electrochemical activities. In their view, consciousness depends on a system’s ability to integrate complex information, to compute particular states from among possible states according to algorithms. Deriving a measure of complex integration from EEG signals termed ‘phi’, they correlate consciousness with critically complex levels of ‘phi’.
Regarding the ‘hard problem’, Koch, Tononi and their physicist colleague Max Tegmark have embraced a form of panpsychism in which consciousness is a property of matter. Simple particles are conscious in a simple way, whereas such particles, when integrated in complex computation, become fully conscious (the ‘combination problem’ in panpsychism philosophy). Tegmark has termed conscious matter ‘perceptronium’, and his alliance with Koch and Tononi is Crick’s legacy and a major force in the present-day science of consciousness. Their view of neurons as fundamental units whose complex synaptic interactions account for consciousness, also supports widely-publicized, and well-funded ‘connectome’ and ‘brain mapping’ projects hoping to capture brain function in neuronal network architecture.
I can see absolutely nothing but gibberish in the vague array alternatives to this sort of approach mentioned by Chopra, Penrose, Hameroff and others: non-computational, quantum superpositional, connected to spacetime geometry, involving coherent cellular microtubule states. Elegant hand waving perhaps, but where is the model? How is it to be tested?