Neurotic Thought

by Deric Bownds

I've done a number of posts on attentional or salience versus default mode long-range connectivity networks in our brains (for a reviewsee my lecture.) They correspond roughly to supporting outward task oriented processes versus inward processes such as daydreaming or imagining. Activity in these networks is thought to be a marker of consciousness, but this idea conflicts with observations that long-range functional connectivities persist even after loss of consciousness caused by anesthesia, or in vegetative state patients. This post is to point to recent work by Dehaene and collaboratorsshowing clear difference in the behavior of long-range networks in awake and anesthetized monkeys. Their abstract and statement of significance, followed by a movie showing whole brain connectivity patterns at different time points in the awake monkey.

Significance

What are the origins of resting-state functional connectivity patterns? One dominating view is that they index ongoing cognitive processes. However, this conclusion is in conflict with studies showing that long-range functional connectivity persists after loss of consciousness, possibly reflecting structural connectivity maps. In this work we respond to this question showing that in fact both sources have a clear and separable contribution to resting-state patterns. We show that under anesthesia, the dominating functional configurations have low information capacity and lack negative correlations. Importantly, they are rigid, tied to the anatomical map. Conversely, wakefulness is characterized by the dynamical exploration of a rich, flexible repertoire of functional configurations. These dynamical properties constitute a signature of consciousness.

Abstract

I haven't been able to post lately, but I'm hoping to be more consistent from now on! Here's a nice piece by Deric Bownds:

Vetter et al. have done the interesting experiment of blindfolding people and then scanning their brains while they listened to birds singing, traffic noise, or people talking. They were able to identify the category of sounds just by examining the pattern of activity in the primary visual cortex, thus making a nice demonstration of the interconnectedness of the brain's sensory systems. Highlights 

•Early visual cortex receives nonretinal input carrying abstract information 

•Both auditory perception and imagery generate consistent top-down input 

•Information feedback may be mediated by multisensory areas 

•Feedback is robust to attentional, but not visuospatial, manipulation

Summary

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)

Abstract:

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.

Paller and Suzuki do a compact review on efforts to define the source of consciousness, arguing against the mysterian position that consciousness is beyond the scope of human understanding. They suggest that this position is like many other flaws in our common intuitions about consciousness. One of these is that if you direct your attention to something you must be aware of it. Not so, as this motion-induced blindness example demonstrates [posted video, focus on the center dot].

If paying attention doesn't guarantee awareness (as is the case in blindsight - in which objects can be discriminated without awareness of seeing them), what is the crucial ingredient? Current work suggests that exchange of information between specific cortical areas seems to be essential.  A clip:

The awareness we each have of our own body and our place in the world seems to be distinctly natural and fundamental. Yet the conscious experience of having a body can be bizarrely disrupted in patients with right parietal damage, who sometimes deny ownership of an entire arm. The rubber-hand illusion is another striking phenomenon, whereby seeing someone rubbing a fake hand while feeling the simultaneous tactile sensation on your own hand momentarily makes you feel that the fake hand is yours. In an even more extreme way, altered neural activity can produce an out-of-body experience.

These unusual perceptual experiences are no less ‘real’ than the sensation of a self inside a body. This standard way we each think of our self is a manufactured sensation, learned on the basis of sensory relationships across modalities. Awareness of a self inhabiting a body is not as obligatory as it seems: it is likely to have evolved for a behavioral advantage.

Why does the brain construct the sensation of a self inside a body? One answer appeals to the idea that you fare better in a social environment when you can attend to your own needs and predict what will happen next, including what other people are going to do. To make this work, specific brain mechanisms evolved to construct models of the attention and intentions of others and to localize them in the corresponding people's heads. The social neuroscience theory of consciousness [see my post on Graziano's ideas] postulates that these same brain mechanisms were adapted to construct a model of one's own attention and intentions, localized in one's own head and perceived as consciousness. If so, a primary function of consciousness is to allow us to predict our own behavior.

Another fragment of text:

...the neural processes that generate the subjective timing of a conscious decision that is seemingly instantaneous may be separate from the more protracted, unconscious processes that generate the content of the decision. The feeling of freely deciding at the precise time of our choosing may be a widespread illusion, albeit a beneficial one that promotes moral behavior and helps us to flourish as social beings.

Finally,

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.

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:

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.

Awake but unconscious

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:

by Neuroskeptic

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.

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:

by Stephen Luntz

Dreams in which the sleeper knows they are dreaming and has some measure of control as to how the events pan out have been stimulated electrically, according to a new paper. 

  Lucid dreaming is the somewhat misleading name given to dreams where the dreamer is aware that they are in fact dreaming. They are not necessarily any clearer than other dreams, but the dreamer can often consciously control the course of the dream, making for a more intelligible experience.

  References to what may be lucid dreaming go back more than 3000 years but the name originated in the late 19th Century. For almost a century the topic was treated with great suspicion. However, in the early 1980s PhD student Stephen Laberge had people who claimed to be able to lucidly dream move their eyes in a pre-agreed fashion while undergoing REM sleep, proving the phenomenon was real.

  Since then there has been much enthusiasm from those who do not lucidly dream, or do so only occasionally, to find a way to experience it regularly. The success of Inception took this quest up a notch. However, many of the techniques proposed are unproven to say the least.

  By publishing in Nature Neuroscience Dr Ursula Voss of the Johann Wolfgang Goethe University has put her claims in a different class, credibility-wise.

  “Lucid dreaming is a very good tool to observe what happens in the brain and what is causally necessary for secondary consciousness,” says Voss. She has found that the brainwaves produced by people who subsequently report experiencing lucid dreams fall somewhere between those of REM-sleep and wakefulness. The frontal and temporal lobes of the brain, responsible for most of what we think of as higher thinking, show lower frequency gamma waves, 25-40Hz, thought to be associated with conscious attention.

  While this may be of interest to sleep researchers, Voss's work is reaching a wider audience since she and Professor J Allan Hobson of Harvard applied electrical stimulation to 27 participants hoping to replicate the same mixture of brainwaves. Voss and Hobson waited until their subjects were showing the signs of REM sleep to apply stimulation to the scalp at various frequencies double blinded from researchers and sleepers alike.

  Despite the participants never having reported lucid dreaming before, when given pulses between 25 and 40Hz brain activity at the same frequency was observed. Higher and lower frequencies had no such effect. When woken 5-10 seconds later some of the subjects given the 25-40Hz reported having been aware that they were dreaming. 

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.

The setup: 

by Neuroskeptic

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.