MedicalResearch.com Interview with:
Veljko Dubljević, Ph.D., D.Phil.
Assistant Professor of Philosophy,
Department of Philosophy and Religious Studies, and
Science Technology and Society Program,
North Carolina State University
Raleigh, NC 27607
MedicalResearch.com: What is the background for this study?
Response: There is considerable controversy about the interpretation of data of the neuroscientific studies done by Benjamin Libet. On the one hand, Libet claimed that his work disproves certain metaphysical conceptions of free will (Libertarianism), whereas it does not disprove others (e.g., Compatibilism). In a nutshell, the reason for these claims is that Libet found preparatory brain activity (Readiness Potentials or RPs) some 500ms before the conscious decision to act was felt by study participants. That seemed to exclude the possibility that mental causation was taking place. At the same time, the onset of movement left a time-window for a 'veto-decision'. This led Libet to conclude that there is no 'free will', but that there is a 'free won't'.
On the other hand, there were many criticisms of the study - methodological or substantive. Most notably, Patrick Haggard argued that it is not RPs that are correlates of a decision to act, but Lateralized Readiness Potentials (LRPs). Haggard agreed with many critics of Libet in that RPs could be connected to a range of other phenomena, and that preparatory brain activity that is most important for a decision to act already has to be 'lateralized'. Namely, the decision to move the left or right arm is critical in this regard, and will lead to RP being focused in one or the other hemisphere, thus making LRPs the point of interest for any conscious decision to act. All in all, Haggard claimed to have replicated Libet's major findings, with the caveat that timing of LRPs excludes the time-frame for a 'veto-decision'. This Haggard claimed makes the evidence more in line with the metaphysical doctrine of 'hard determinism', which excludes agency and responsibility.
Many other neuroscientists followed Libet's (and Haggard's) lead and these experiment became part of 'lore' in neuroscience education - many other labs performed similar experiments and claimed to basically replicate the findings.
Our study was the first to review all available evidence.
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Author Interviews, Circadian Rhythm, Neurological Disorders, Neurology / 21.04.2017
Considering Circadian Rhythms May Aide in Diagnosis of Consciousness Disorders
MedicalResearch.com Interview with:
Dr. Christine Blume PhD
Post-Doctoral Researcher
University of Salzburg
Centre for Cognitive Neuroscience (CCNS)
Laboratory for Sleep, Cognition & Consciousness Research
Salzburg
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: We are governed by rhythmic processes. Many of these processes follow a circadian pattern, that is, they have a period length of approximately 24 hours and are under tight control of a biological master clock located in the suprachiasmatic nucleus of the hypothalamus. Given the circadian variation in global states like alertness, it is not surprising that consciousness also varies rhythmically in healthy individuals, it follows the sleep-wake cycle.
From a clinical perspective, misalignment of circadian rhythms, which occurs when the sleep-wake schedule is at odds with the light-dark cycle as in the case of night shifts, can cause considerable stress, have detrimental effects on the immune system and impair cognitive abilities. Despite the knowledge that entrained circadian rhythms are important for healthy body and brain functioning, very little is known about circadian rhythms in patients diagnosed with a disorder of consciousness (DOC) following severe brain injuries. We argue that studying circadian rhythms in DOC patients may be especially interesting and important for two reasons.
First, the presence or absence of circadian rhythms as well as anomalies in them could be informative about the state of the patient as well as their potential for recovery.
Second, this could provide information about time points that best capture remaining cognitive functions thereby minimising the risk of misdiagnoses.
Beyond this, examining circadian processes may also provide targets for therapeutic interventions such as light stimulation, which has proven successful in individuals with e.g. circadian sleep disorders. Interestingly, analyses with Lomb-Scargle periodograms revealed significant circadian rhythmicity in all patients (range 23.5-26.3h).
We found that especially scores on the arousal subscale of the Coma Recovery Scale-Revised (CRS-R) were closely linked to the integrity of circadian variations in body temperature.
Finally, we piloted whether bright light stimulation could boost circadian rhythmicity and found positive evidence in two out of eight patients.
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MedicalResearch.com Interview with:
DR. Y. (YAÏR) PINTO
Faculty of Social and Behavioural Sciences
Programme group Brain and Cognition
UvA
MedicalResearch.com: What is the background for this study?
Response: I've done research into patients in whom the corpus callosum was entirely removed surgically, at an adult age, to relieve epileptic seizures. The removal of the corpus callosum all but eliminates communication between both cerebral hemispheres. Therefore these patients are referred to as split-brain patients.
The canonical view of these patients is that their consciousness is split as well. That is, the notion, which is found in many textbooks and reviews, is that in a split-brain patient each hemisphere is an conscious agent, independent of the other hemisphere.
This notion is mainly based on the following key observation. When an image is presented to the left visual field, the patient indicates verbally, and with his right hand, that he saw nothing. Yet, with his left hand he indicates that he did see the object! Conversely, if a stimulus appears in his right visual field, he will indicate awareness of this stimulus when he responds verbally or with his right, yet with his left hand he will report that he saw nothing. This exactly fits the notion that in a split-brain patient the two separated hemispheres each become an independent conscious agent. The left hemisphere perceives the right visual field, controls language and the right side of the body. The right hemisphere experiences the left visual field and controls the left hand. This, and other discoveries on split-brain patients, earned Roger Sperry the nobel-prize in Medicine in 1981.
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Author Interviews, Brigham & Women's - Harvard, Neurological Disorders / 17.11.2016
Brain Network Connected To Consciousness and Awareness Identified
MedicalResearch.com Interview with:
Michael D. Fox, MD, PhD
Assistant Professor in Neurology
Berenson-Allen Center for Noninvasive Brain Stimulation
Division of Cognitive Neurology, Department of Neurology
Beth Israel Deaconess Medical Center
Boston, MA
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Consciousness is thought to be composed of arousal plus awareness, but no one knows where these processes live in the human brain.
We took a unique approach to this question by studying human brain lesions that disrupt consciousness and cause coma.
We found one small spot in the brainstem that was specific for coma (i.e. lesions that hit this spot caused coma while lesions that didn’t hit the spot did not cause coma).
In other words, there was one spot in the human brainstem that, when lesioned, disrupted arousal and caused coma
We then looked at the connectivity of that brainstem spot, and found that it was connected to two cortical regions previously implicated in awareness. These cortical regions also contained a unique type of brain cell thought only to be present in higher order mammals that are self-aware.
To confirm our findings, we looked at the integrity of our network in patients with disorders of consciousness (e.g. persistent vegetative state) and found selective disruption of this network.
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MedicalResearch.com Interview with:
Ezequiel Morsella, Ph.D.
Associate Professor of Neuroscience
Department of Psychology San Francisco State University
Assistant Adjunct Professor Department of Neurology
University of California, San Francisco
Boardmember, Scientific Advisory Board
Institute of Cognitive Neurology (INECO), Buenos Aires
Medical Research: What is the background for this study? What are the main findings?
Dr. Morsella: The theoretical framework, Passive Frame Theory, builds on an action-based, theoretical project that first appeared in Psychological Review, in 2015.
The framework is a synthesis of hypotheses from disparate fields. It reveals that consciousness serves as a frame that constrains and directs skeletal muscle output, thereby yielding adaptive behavior. From this unique, action-based perspective, consciousness is in the service of the somatic nervous system. How consciousness achieves this is more counterintuitive, ‘low level,’ and passive than the kinds of functions that theorists have attributed to consciousness.
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