U. Voss, R. Holzmann, I. Tuin, J.A. Hobson
Article in Sleep

Abstract
Study Objectives: The goal of the study was to seek physiological correlates of lucid dreaming. Lucid dreaming is a dissociated state with aspects of waking and dreaming combined in a way so as to suggest a specific alteration in brain physiology for which we now present preliminary but intriguing evidence. We show that the unusual combination of hallucinatory dream activity and wake-like reflective awareness and agentive control experienced in lucid dreams is paralleled by significant changes in electrophysiology.

Design: 19-channel EEG was recorded on up to 5 nights for each participant. Lucid episodes occurred as a result of pre-sleep autosuggestion.

Setting: Sleep laboratory of the Neurological Clinic, Frankfurt University.

Participants: Six student volunteers who had been trained to become lucid and to signal lucidity through a pattern of horizontal eye movements.

Measurements and Results: Results show lucid dreaming to have REM-like power in frequency bands delta and theta, and higher-than-REM activity in the gamma band, the between-states-difference peaking around 40 Hz. Power in the 40 Hz band is strongest in the frontal and frontolateral region. Overall coherence levels are similar in waking and lucid dreaming and significantly higher than in REM sleep, throughout the entire frequency spectrum analyzed. Regarding specific frequency bands, waking is characterized by high coherence in alpha, and lucid dreaming by increased delta and theta band coherence. In lucid dreaming, coherence is largest in frontolateral and frontal areas.

Conclusions: Our data show that lucid dreaming constitutes a hybrid state of consciousness with definable and measurable differences from waking and from REM sleep, particularly in frontal areas.

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Petr Bob
Review article in Consciousness and Cognition

Abstract:
According to recent evidence, neurophysiological processes coupled to pain are closely related to the mechanisms of consciousness. This evidence is in accordance with findings that changes in states of consciousness during hypnosis or traumatic dissociation strongly affect conscious perception and experience of pain, and markedly influence brain functions. Past research indicates that painful experience may induce dissociated state and information about the experience may be stored or processed unconsciously. Reported findings suggest common neurophysiological mechanisms of pain and dissociation and point to a hypothesis of dissociation as a defense mechanism against psychological and physical pain that substantially influences functions of consciousness. The hypothesis is also supported by findings that information can be represented in the mind/brain without the subject’s awareness. The findings of unconsciously present information suggest possible binding between conscious contents and self-functions that constitute self-representational dimensions of consciousness. The self-representation means that certain inner states of own body are interpreted as mental and somatic identity, while other bodily signals, currently not accessible to the dominant interpreter’s access are dissociated and may be defined as subliminal self-representations. In conclusion, the neurophysiological aspects of consciousness and its integrative role in the therapy of painful traumatic memories are discussed.

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In a past study, Klimesch and colleagues examined whether the conscious experience of remembering and knowing are associated with neural synchronization in the theta bandwidth.  These investigators first presented participants with a series of words (through both auditory and visual means) and then tested participants’ memory for these words using a recognition test and the “Remember-Know” task. 

During the recognition test, participants were shown a series of words (the participants saw some of these words earlier during the experiment, whereas other words were not seen before) and were asked to judge whether these same words were presented to them earlier.  For those words that were judged as “old” (previously presented), participants also performed the Remember-Know task. 

The Remember-Know task is widely used in memory research to study one’s state of consciousness during a recognition decision.  ”Remember” judgments are made when an “old” decision on the recognition test is accompanied by awareness of details of the previous occurrence of the stimulus in question.  “Know” judgments are made when an “old” decision is not accompanied by such awareness.

Among other interesting results, Klimesch and colleagues found that theta power was larger for Know judgments early during the recognition period of a word (300 - 450 ms) and larger for Remember judgments during a later period (450 - 625 ms). The investigators concluded that these patterns of theta associated with Remember and Know judgments demonstrate that the temporal dynamics of the neural synchronization plays an important role in the experiential characteristics associated with memory retrieval.

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From MindHacks
An article in this week’s Science News discusses whether the brain stem may play a more central role in consciousness than it’s usually given credit for.

It focuses on children with hydranencephaly, a where the cortex fails to develop in children and instead, the space is filled with cerebral spinal fluid.

Typically, affected children survive only a few months after birth, but those that do survive seem to remarkably more conscious than you would guess based on theories that suggest the cortex is where all the action happens to support consciousness.

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The benefits of deep-brain stimulation for a minimally conscious patient have recently been reported in the journal Nature (click here for the article), as presented in a previous SCR post by Thomas Ramsoy. Here is another article on this same minimally conscious patient, whose identity remains undisclosed, written by Tom Valeo (image from the article).

Click here to watch a video on Sarah Scantlin, a patient who was stuck in a minimally conscious state for 20 years.

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Neuroscientists and engineers are developing ways to help patients overcome paralysis and stroke. But what about mental function itself? Can medical intervention restore consciousness?

Nature runs a story on thalamic stimulation after severe stroke. Could this method be applied to help patients in coma or vegetative state regain their mental life?

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Visual (and other non-visual) hallucinations sometimes occur during epileptic seizures. A relatively straightforward but little used method to describe these experiences is to ask the sufferer to draw the hallucinations — even as they occur.

According to G.D. Schott, in an article in the latest issue of Brain, such descriptions not only not only serve as tools to understand the sufferer and symptoms; they can also be used for differential diagnosis. 

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What is the nature of thought? And what is the resting state? Moshe Bar and colleagues argues in a new paper (PDF) in the journal Hippocampus that besides the long-held idea that associative processing provides the vehicle of thought, that “one primary outcome of associative processing is the generation of predictions, which approximate the immediately relevant future and thus facilitate perception, action, and the progression of thought”.

From the article:

Associations are proposed to provide the units of thought,b ut they should not be perceived as the actual content of thought; they merely provide the vehicle for linking related representations. In fact, our proposal is that the primary role of associations and associative activation is to generate predictions, which guide our actions, expectations, plans, and thoughts. To elaborate on this it will be useful to consider our broader theoretical framework: We propose that rather than passively ‘‘waiting’’ to be activated by sensations, the human brain is constantly busy generating predictions that approximate the immediate, directly relevant, future. Building on previous work, this proposal posits that rudimentary information is first extracted rapidly from a perceptual input, and then used to derive analogies linking the input with the most similar representations in memory. The linked stored representations in turn selectively activate the associations that are relevant in the specific context, which provides focused, testable predictions. These predictions facilitate perception and cognition by presensitizing representations all the way downstream to primary cortices. For example, we see a fork, the image of which will

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Nature has an interesting report from Marc Raichle’s laboratory that studies the resting states in monkeys. This study not only demonstrates that resting states occur in non-human primates, but that it is possible to find such activity during unconscious states.

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What is the relation between emotion and consciousness? In their recent paper in TRENDS in Cognitive Sciences, Tsuchiya and Adolphs review recent studies that address this question. 

Focusing on domains where emotion and consciousness overlap and interact, Tsuchiya and Adolphs suggest that each (emotion and consciousness) is necessary for aspects of the other.  They follow the common view that emotion and consciousness result from neuronal activity in the brain and they argue that both emotion and consciousness depend on neural representations of one’s own body.  Moreover, Tsuchiya and Adolphs argue that these representations arise from structures in the brainstem and medial telencephalon that receive interoceptive information.  The authors believe that future work requires not only more data but also further theoretical development of the relevant concepts that are currently under investigation.

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There is an interesting article in TIME, by Steven Pinker, about the study of consciousness. From the article:

As every student in Philosophy 101 learns, nothing can force me to believe that anyone except me is conscious. This power to deny that other people have feelings is not just an academic exercise but an all-too-common vice, as we see in the long history of human cruelty. Yet once we realize that our own consciousness is a product of our brains and that other people have brains like ours, a denial of other people’s sentience becomes ludicrous. “Hath not a Jew eyes?” asked Shylock. Today the question is more pointed: Hath not a Jew–or an Arab, or an African, or a baby, or a dog–a cerebral cortex and a thalamus? The undeniable fact that we are all made of the same neural flesh makes it impossible to deny our common capacity to suffer.

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TIME and CNN present an interesting video on Sarah Scantlin, a patient who suffers from severe brain damage. After being stuck in what was thought to be a vegetative state for 20 years, Sarah has recently regained her ability to speak. Scientists now think that Sarah was in a minimally conscious state, described as having a low level of awareness but conscious nonetheless, for the past two decades. It is noted that while some regions of Sarah’s brain are damaged, other regions are struggling to make new connections. (Image from the video.)

When asked whether she felt asleep or trapped for the last 20 years, Sarah reported having felt trapped. Amongst other challenges, Sarah seems to lack a concept of time, leaving her to believe that she is still 18 (the age at which she incurred her brain injury) when in fact she is now at the age of 40 years.

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