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?
Meditation as object of medical research
Mindfulness meditation produces personal experiences that are not readily interpretable by scientists who want to study its psychiatric benefits in the brain. At a conference near Boston April 5, 2014, Brown University researchers will describe how they’ve been able to integrate mindfulness experience with hard neuroscience data to advance more rigorous study.
Mindfulness is always personal and often spiritual, but the meditation experience does not have to be subjective. Advances in methodology are allowing researchers to integrate mindfulness experiences with brain imaging and neural signal data to form testable hypotheses about the science — and the reported mental health benefits — of the practice.
A team of Brown University researchers, led by junior Juan Santoyo, will present their research approach at 2:45 p.m on Saturday, April 5, 2014, at the 12th Annual International Scientific Conference of the Center for Mindfulness at the University of Massachusetts Medical School. Their methodology employs a structured coding of the reports meditators provide about their mental experiences. That can be rigorously correlated with quantitative neurophysiological measurements.
“In the neuroscience of mindfulness and meditation, one of the problems that we’ve had is not understanding the practices from the inside out,” said co-presenter Catherine Kerr, assistant professor (research) of family medicine and director of translational neuroscience in Brown’s Contemplative Studies Initiative. “What we’ve really needed are better mechanisms for generating testable hypotheses – clinically relevant and experience-relevant hypotheses.”
Now researchers are gaining the tools to trace experiences described by meditators to specific activity in the brain.
“We’re going to [discuss] how this is applicable as a general tool for the development of targeted mental health treatments,” Santoyo said. “We can explore how certain experiences line up with certain patterns of brain activity. We know certain patterns of brain activity are associated with certain psychiatric disorders.”
Structuring the spiritual
At the conference, the team will frame these broad implications with what might seem like a small distinction: whether meditators focus on their sensations of breathing in their nose or in their belly. The two meditation techniques hail from different East Asian traditions. Carefully coded experience data gathered by Santoyo, Kerr, and Harold Roth, professor of religious studies at Brown, show that the two techniques produced significantly different mental states in student meditators.
“We found that when students focused on the breath in the belly their descriptions of experience focused on attention to specific somatic areas and body sensations,” the researchers wrote in their conference abstract. “When students described practice experiences related to a focus on the nose during meditation, they tended to describe a quality of mind, specifically how their attention ‘felt’ when they sensed it.”
The ability to distill a rigorous distinction between the experiences came not only from randomly assigning meditating students to two groups – one focused on the nose and one focused on the belly – but also by employing two independent coders to perform standardized analyses of the journal entries the students made immediately after meditating.
This kind of structured coding of self-reported personal experience is called “grounded theory methodology.” Santoyo’s application of it to meditation allows for the formation of hypotheses.
For example, Kerr said, “Based on the predominantly somatic descriptions of mindfulness experience offered by the belly-focused group, we would expect there to be more ongoing, resting-state functional connectivity in this group across different parts of a large brain region called the insula that encodes visceral, somatic sensations and also provides a readout of the emotional aspects of so-called ‘gut feelings’.”
Unifying experience and the brain
The next step is to correlate the coded experiences data with data from the brain itself. A team of researchers led by Kathleen Garrison at Yale University, including Santoyo and Kerr, did just that in a paper in Frontiers in Human Neuroscience in August 2013. The team worked with deeply experienced meditators to correlate the mental states they described during mindfulness with simultaneous activity in the posterior cingulate cortex (PCC). They measured that with real-time functional magnetic resonance imaging.
They found that when meditators of several different traditions reported feelings of “effortless doing” and “undistracted awareness” during their meditation, their PCC showed little activity, but when they reported that they felt distracted and had to work at mindfulness, their PCC was significantly more active. Given the chance to observe real-time feedback on their PCC activity, some meditators were even able to control the levels of activity there.
“You can observe both of these phenomena together and discover how they are co-determining one another,” Santoyo said. “Within 10 one-minute sessions they were able to develop certain strategies to evoke a certain experience and use it to drive the signal.”
A theme of the conference, and a key motivator in Santoyo and Kerr’s research, is connecting such research to tangible medical benefits. Meditators have long espoused such benefits, but support from neuroscience and psychiatry has been considerably more recent.
In a February 2013 paper in Frontiers in Human Neuroscience, Kerr and colleagues proposed that much like the meditators could control activity in the PCC, mindfulness practitioners may gain enhanced control over sensory cortical alpha rhythms. Those brain waves help regulate how the brain processes and filters sensations, including pain, and memories such as depressive cognitions.
Santoyo, whose family emigrated from Colombia when he was a child, became inspired to investigate the potential of mindfulness to aid mental health beginning in high school. Growing up in Cambridge and Somerville, Mass., he observed the psychiatric difficulties of the area’s homeless population. He also encountered them while working in food service at Cambridge hospital.
“In low-income communities you always see a lot of untreated mental health disorders,” said Santoyo, who meditates regularly and helps to lead a mindfulness group at Brown. He is pursuing a degree in neuroscience and contemplative science. “The perspective of contemplative theory is that we learn about the mind by observing experience, not just to tickle our fancy but to learn how to heal the mind.”
It’s a long path, perhaps, but Santoyo and his collaborators are walking it with progress.
Evolved music specific brain reward systems. -
by Deric Bownds
Perhaps the most plausible suggestion for why music is universal in human societies is that it plays a central role in emotional social signaling that could have promoted group cohesion. Clark et al.comment on new work by Mas-Herrero et al. who have now documented a group of healthy people who, while responding to typical rewarding stimuli, appear to have a specific musical anhedonia, deriving no pleasure from music even though perceiving it normally. They cannot experience the intensely pleasurable shivers down the spine or ‘chills’ that are specific to and reliably triggered by particular musical features like the resolution of tonal ambiguity. These active a distributed brain network including phylogenetically ancient limbic, stratal and midbrain structures also engaged by cocaine and sex. Clips from Clark et al.:
The musical anhedonia found by Mas-Herreo et al. is specific for musical reward assignment, rather than attributable to any deficiency in perceiving or recognising music or musical emotions. It is rooted in reduced autonomic reactivity rather than simply cognitive mislabelling. Moreover, it is not attributable to more general hedonic blunting, because musically anhedonic individuals show typical responses to other sources of biological and non-biological (monetary) reward. The most parsimonious interpretation of the new findings is that there are music-specific brain reward systems to which individuals show different levels of access….specific brain substrates for music coding … implies that these evolved in response to some biological imperative. But what might that have been?
The answer may lie in the kinds of puzzles that music helped our hominid ancestors to solve. Arguably the most complex, ambiguous and puzzling patterns we are routinely required to analyse are the mental states and motivations of other people, with clear implications for individual success in the social milieu. Music can model emotional mental states and failure to deduce such musical mental states correlates with catastrophic inter-personal disintegration in the paradigmatic acquired disorder of the human social brain, frontotemporal dementia …Furthermore, this music cognition deficit implicates cortical areas engaged in processing both musical reward and ‘theory of mind’ (our ability to infer the mental states of other people). Our hominid ancestors may have coded surrogate mental states in the socially relevant form of vocal sound patterns. By allowing social routines to be abstracted, rehearsed and potentially modified without the substantial cost of enacting the corresponding scenarios, such coding may have provided an evolutionary mechanism by which specific brain linkages assigned biological reward value to precursors of music.
These new insights into musical anhedonia raise many intriguing further questions. What is its neuroanatomical basis? The strong prediction would lie with mesolimbic dopaminergic circuitry, but functional neuroimaging support is sorely needed.
Here is the summary from the Mas-Herrero paper:
Music has been present in all human cultures since prehistory, although it is not associated with any apparent biological advantages (such as food, sex, etc.) or utility value (such as money). Nevertheless, music is ranked among the highest sources of pleasure, and its important role in our society and culture has led to the assumption that the ability of music to induce pleasure is universal. However, this assumption has never been empirically tested. In the present report, we identified a group of healthy individuals without depression or generalized anhedonia who showed reduced behavioral pleasure ratings and no autonomic responses to pleasurable music, despite having normal musical perception capacities. These persons showed preserved behavioral and physiological responses to monetary reward, indicating that the low sensitivity to music was not due to a global hypofunction of the reward network. These results point to the existence of specific musical anhedonia and suggest that there may be individual differences in access to the reward system.
Out of body - out of memory -
by Janet Kwazniak
ScienceDaily (here) has an item on an interesting paper: Loretxu Bergouignan, Lars Nyberg, and H. Henrik Ehrsson. Out-of-body–induced hippocampal amnesia. Proceedings of the National Academy of Sciences, March 10, 2014.
Our feeling of our bodies is important to storing/retrieving episodic memories. The experimenters had subjects using virtual reality googles which either left them with their own bodies or forced an ‘out-of-body’ illusion. The subjects could remember the events that happened when their body image was not disturbed. When they tried to remember events that happened when they felt out of their bodies – they had difficulty. Henrik Ehrsson is quoted as saying,“The fMRI scans further revealed a crucial difference in activity in the portion of the temporal lobe — the hippocampus — that is known to be central for episodic memories. When they tried to remember what happened during the interrogations experienced out-of-body, activity in the hippocampus was eliminated, unlike when they remembered the other situations. However, we could see activity in the frontal lobe cortex, so they were really making an effort to remember.”
I am inclined to think that memory is a question of saving experiences that may be useful. We know that the hippocampus associates our location with events in memory and that it tracks the timing or ordering of events. There is also often a mood and emotional colouring to remembered events. And extremely important is the sense of how much is invested and how much ownership is taken in events. We remember effort. We remember errors. We remember hard decisions. We remember good places and people and we remember bad ones too. To put it simply, we remember what may be useful. What happened when our bodies were not involved is not very useful – it might as well be someone else’s event.
I remember things that happened to other people and I can picture them happening to me. But I know that it did not happen to me. My body was not there. Those memories started as words in a story being told to me and they carry that lack of first-hand involvement. What happens with an experience that has neither our own body’s involvement nor someone else’s body? Perhaps it is – no identifiable agent – no memory.