Tag Archives: neuroscience

Man in Vegetative State Shows Brain Activity to Movie: What Does It Mean?

In a recent study, Naci et al. investigated how the brain responds to an 8 minute Alfred Hitchcock movie. In healthy subjects they found that frontal and parietal areas indicative of executive functioning were active during the most suspenseful parts of the movie. Then they showed the same movie to two patients diagnosed as being in a vegetative state, one of which who had been in VS for 16 years. In one of the patients they found that “activity in a network of frontal and parietal regions that are known to support executive processing significantly synchronized to that of healthy participants”. In other words, the vegetative man’s brain “tracked” the suspense-points of the movie in the same way that healthy controls did. They reasoned that the patient was therefore consciously aware of the video, despite being behaviorally unresponsive:

The patient’s brain activity in frontal and parietal regions was tightly synchronized with the healthy participants’ over time, and, crucially, it reflected the executive demands of specific events in the movie, as measured both qualitatively and quantitatively in healthy individuals. This suggested that the patient had a conscious cognitive experience highly similar to that of each and every healthy participant, while watching the same movie.

But what’s the connection between executive functioning and conscious experience? The authors write:

The “executive” function of the brain refers to those processes that coordinate and schedule a host of other more basic cognitive operations, such as monitoring and analyzing information from the environment and integrating it with internally generated goals, as well as planning and adapting new behavioral schemas to take account of this information. As such, executive function is integral to our conscious experience of the world as prior knowledge is integrated into the current “state of play” to make predictions about likely future events.

Does this mean that executive functioning is always conscious? Is the unconscious brain incapable of “monitoring and analyzing information from the environment” and “integrating” that information with goals? Color me skeptical but I believe in the power of the unconscious mind to perform these functions without the input of conscious awareness.

Several examples come to mind. In the “long-distance truck driver” phenomenon people can drive automobiles for minutes if not hours without the input of conscious awareness. Surely driving requires “monitoring and analyzing information from the environment” in addition to integrating with goals and adapting new behaviors to deal with novel road conditions.

Another example is automatic writing, where people can write whole intelligent paragraphs without the input of conscious attention and the “voice” of the writing is distinct from that of the person’s normal personality, channeling the personalities of deceased persons or famous literary people. People would hold conversations with their automatic writing indicating that the unconscious writer was responding to the environment and surely “monitoring and analyzing information”. Im not aware of any brain imaging studies of automatic writing but I would not be surprised if frontal and parietal regions were active given the complexity of handwriting as a cognitive task. Same with long-distance truck driving.

My point is simply to raise the question: Can executive function happen unconsciously? Naci et al. say that executive function is “integral” to conscious experience. That might be true. But is conscious experience integral to executive functioning? Maybe not. There is a litany of complex behaviors that can be performed unconsciously, all of which likely recruit frontal and parietal networks of the brain. We can’t simply assume that just because information integration occurred that conscious awareness was involved. To make that inference would require us to think that the unconscious mind is “dumb” and incapable of integrating information. But there is plenty of reason to think that what Timothy Wilson calls the “adaptive unconscious” is highly intelligent and capable of many “higher-order” cognitive functions including monitoring, integrating, planning, reasoning, etc.

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Quote of the day – Depth of Processing in the Vegetative State

“In the [vegetative state] or [minimally conscious state] the EEG is by definition not flat and typically shows widespread slowing of brain rhythms. Does this mean that nothing is being processed? The answer is a definite ‘no’. A clear analogy is the emerging literature on the depth of processing of environmental input (i.e., the surgeon talking about something in the operating room) while the patient is under anesthesia with widespread EEG slowing akin to that observed in VS and MCS. By this logic it would be surprising if some sensory input were not being processed in all VS patients and certainly in all MCS patients. By extension, one might also propose that some internal thoughts are being generated in these devastating clinical states.

Indeed, the key issue from the neurologist’s perspective is whether the neurological insult, whether prolong hypoxia or severe traumatic brain injury, will leave any meaningful brain function. So, it is not clear if the key issue is ‘consciousness’ or the clinical experience with these patients per long-term recovery of ‘meaningful’ life. Of course, meaningful is as poorly defined as consciousness and herein lies the quandary.”

~ Robert Knight, (2008) “Consciousness Unchained: Ethical Issues and the Vegetative and Minimally Conscious State” The American Journal of Bioethics, 8(9): 1–2

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Neuronal Panpsychism

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Panpsychism is the view that everything has a mental life. Many people find this implausible because it seems weird to think that rocks and dust bunnies are cognizers in the same way that people or animals are cognizers. Panpsychism also seems to contradict the growing consensus among neuroscientists who claim that consciousness only “arises” when a certain level of cortical connectivity or information integration is present in the brain, especially in fronto-parietal circuits and other “global workspaces”.

But why think you need a sophisticated network of cortico-cortical activity in order to have a mind, to have a point of view on the world? Why not think a single neuron is a locus of mental experience? Perhaps there is a faint “something-it-is-like” from the point of view of individual neurons. I call this view neuronal panpsychism: it says that every neuron has a distinct mental life independent of its interaction with any other neuron. Of course a neurons experience is going to be significantly impacted by its causal and reciprocal interaction with neighboring neurons but the point is that the neurons themselves are loci of experience in virtue of their intrinsic nature.

But how do we account for the reams of data suggesting that a high-level of connectivity is necessary for what Stan Dehaene calls “conscious ignition”? After all, even coma patients have some preserved neuronal activity but no one thinks they are conscious: they show no external signs of consciousness at least.

The key to explaining this data in a way that’s consistent with neuronal panpsychism is the “nesting” solution. The idea is that the “macro” consciousness of normal human adults is actually composed of the “micro” experiences of all the individual neurons. The feeling of global unity is therefore an illusion according to neuronal panpsychism. The feeling of being one great unified stream of experience is actually an aggregate of billions of microexperiences in the same way that a river is composed of countless water atoms.

But what does it mean for experiences to “add up” in this way? Is there an equivalent of multiplication or taking the integral? These are tough, unresolved theoretical issues facing all brands of panpsychism. But is it any less mysterious than saying consciousness “arises” whenever informational connectivity reaches a certain threshold in frontal-parietal circuits or when there is 40z synchrony or whatever?

I actually think though neuronal panpsychism can make sense of why it feels different to have your frontal-parietal circuits activated or deactivated and why these circuits seem to make both a significant phenomenal and functional difference to the “macro” level experience of normal human adults. Neuronal panpsychism says that all neurons have mental states but that doesn’t mean they all have the same kind of mental states. For example, a motor neuron might have a different experience than a Von Economo neuron, or a cerebellar neuron might have a different experience than a neuron than lives in the prefrontal cortex.

In effect neuronal panpsychism is a kind of microfunctionalism where neurons with different functional profiles have different mental lives. These functional differences arise from both their phylo and ontogenetic history i.e. different types of neurons have different inherited genetic programming but they also have unique, individualized learning experiences.Thus. the differences in felt macro experiences when there are high levels of frontal-parietal activity are due to the unique experiences of those neurons being added to the choir of subcortical neurons. But they are not the origin of phenomenality, only the “loudest” phenomenality or “most famous” phenomenality, to borrow a metaphor from Dan Dennett’s “fame in the brain” theory (which is an intellectual precursor to neuronal panpsychism).

Thus, when a vegetative patient is transitioning to the minimally conscious state and onwards to normal consciousness there is never one unique threshold when consciousness gets “turned on”. Consciousness is not all or nothing. Consciousness is not a special property of only a unique set of cortical circuits in mammals with sufficiently activated global workspaces. According to neuronal panpsychism, ALL neurons contribute to what-it’s-like to be a unified mind or “I”.

But why stop at neurons? Why not think glial cells have mental lives too? Indeed, why not claims all cells have mental lives? This would be “cellular panpsychism”. But that’s another post.

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The Inner Life of Vegetative Patients and Why It Matters

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Here’s the latest draft of my paper on covert consciousness in the vegetative state, which is still very much a work-in-progress. If you compare it to the earlier draft I posted, you can see I am taking the paper in a more bioethical direction, which is a whole new ballgame for me. Comments welcome.

Abstract: Adrian Owen and colleagues (2006 et al.) report using functional neuroimaging to detect residual levels of conscious awareness in patients diagnosed with vegetative state syndrome. These studies have generated immense scientific and public interest largely due to the putative moral significance of consciousness. These findings raise vexing philosophical and ethical questions about the nature of consciousness and its moral significance. My goal in this paper is to critically examine these findings and evaluate their significance from a clinical-ethical perspective. The general lesson is that determining the moral significance of consciousness is complex and multifaceted.

Link to PDF: Williams 4-24-14-InnerLifeofVegetativePatients

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Draft of Latest Paper – Awake But Not Aware: Probing For Consciousness in Unresponsive Patients

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Ok everyone, here’s a paper I’m really excited about. The topic is so “me” — the first project I’ve wholeheartedly thrown myself into since since I came to Wash U. I can see myself wanting to write a dissertation or book on the topic so this paper will likely serve as the basis for a prospectus in the near future. The issue I’m dealing with in the paper is situated at the intersection of a variety of fields ranging from philosophy of mind, philosophy of science, cutting edge neuroscience, clinical neurology and biomedical ethics. I could conceivably “sell” the project to a variety of people. The project is obviously at an early stage of development and the paper is drafty but I have the rest of the semester to work on this so I’m open to any comments, criticisms, or questions. Thanks!

For PDF of paper, click here –> Williams-AwakeButNotAware-Draft-3-03-14

Here’s a tentative abstract:

The standard approach in clinical neurology is to diagnose disorders of consciousness (DOC) on the basis of operationally defined behaviors. Critics of the standard approach argue that it relies on a flawed behaviorist epistemology that methodologically rules out the possibility of covert consciousness existing independently of any observable behavior or overt report. Furthermore, critics point to developments in neuroimaging that use fMRI to “actively probe” for consciousness in unresponsive patients using mental imagery tasks (Owen et al. 2006). Critics argue these studies showcase the limitations of the standard approach. The goal of this paper is to defend the standard approach against these objections. My defense comes in two parts: negative and positive. Negatively, I argue that these new “active probe” techniques are inconclusive as demonstrations of consciousness. Positively, I reinterpret these active probes in behavioral terms by arguing they are instances of “brain behaviors”, and thus not counterexamples to the standard approach.

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Beginning to Work on Something Long

Now that I am almost done with coursework — nearly three years later — I am finally beginning to think about something long – a dissertation. To write a dissertation I need a topic, and I think might I have one: measuring consciousness in persistent vegetative state or minimally conscious patients. I got interested in this topic last Fall when I read Nachev and Hacker’s paper “Covert cognition in the persistent vegetative state” for Carl Craver’s class Current Controversies in Cognitive Science. The paper is excellent and raises many fascinating questions. Some questions that I would like to answer in the dissertation include:

  • What does it mean to be a PVS or minimally conscious patient? What’s their respective neurology?
  • What exactly are we trying to detect in these patients? How is “consciousness” defined?
  • What measurement methods are we using and why? How is “consciousness” operationalized? Can it even be measured?
  • How can we arbitrate between rival operational measures of consciousness? How can we verify we are detecting what we think we are detecting?
  • Is the thing we are trying to detect worth detecting? What should we be looking for?
  • How do we determine an acceptable false positive/false negative rate?

This topic is at the intersection of many of my interests: consciousness, philosophy of science, operationalism, behaviorism, and ethics. This semester I am doing directed research with Carl Craver to dive head-first into the topic. I have a long reading list that I will be working my way through and hopefully I’ll be able to share some of my findings as the semester progresses. Stay tuned!

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New paper – Measuring Mental Time Travel in Animals

For pdf click here: Williams – Measuring Mental Time Travel In Animals

Hasok Chang describes in Inventing Temperature how scientists dealt with the problem of measurement verification circularity when standardizing the first thermometers ever constructed. The problem can be illustrated by imagining you are the first scientist who wanted to measure the temperature of boiling water. What materials should you use to construct the measuring instrument? Once built, how do you verify your thermometer is measuring what you claim it is without circularly relying on your thermometer? Appealing to more experimentation is unhelpful because we must use a thermometer to carry out these experiments, and thermometers are what we are trying to determine the reliability of in the first place. Hasok Chang calls this the Problem of Nomic Measurement (PNM), which is defined as:

The problem of circularity in attempting to justify a measurement method that relies on an empirical law that connects the quantity to be measured with another quantity that is (more) directly observable.1 The verification of the law would require the knowledge of various values of the quantity to be measured, which one cannot reliably obtain without confidence in the method of measurement.

Stated more precisely, the PNM goes as follows:

1. We want to measure unknown quantity X.

2. Quantity X is not directly observable, so we infer it from another quantity Y, which is directly observable.

3. For this inference we need a law that expresses X as a function of Y, as follows:X = f(Y).

4. The form of this function f cannot be discovered or tested empirically because that would involve knowing the values of both Y and X, and X is the unknown variable that we are trying to measure.

My aim for this paper is to apply the PNM to an on-going debate in cross-comparative psychology about whether and to what extent non-human animals can “mentally time travel”. In 1997, Suddendorf and Corballis argued “the human ability to travel mentally in time constitutes a discontinuity between ourselves and other animals”.2 In 2002, Roberts argued non-human animals are “stuck-in-time”. Since then, a number of psychologists have defended similar claims. Endel Tulving states this hypothesis clearly:

There is no evidence that any nonhuman animals—including what we might call higher animals—ever think about what we could call subjective time…they do not seem to have the same kind of ability humans do to travel back in time in their own minds, probably because they do not need to. (Tulving, 2002, p. 2)

Call the claim that mental time travel is unique to humans Uniqueness. Naturally, Uniqueness has not gone unchallenged. One worry is that different theoretical assumptions about what counts as “mental time travel” are leading to disagreements over whether animals do or do not possess MTT. Furthermore, both sides of the debate more or less agree about the behavioral evidence, but disagree about how to interpret the evidence qua evidence for or against Uniqueness. This raises a problem of verification circularity similar to the PNM:

1. We want to measure MTT in animals

2. MTT is not directly observable, so we infer it from behavior Y, which is directly observable.

3. For this to work, we need to know how to infer MTT from behavior alone.

4. The form of this function cannot be discovered or tested empirically because that would involve knowing the unknown variable we are trying to measure (MTT).

Accordingly, my central thesis is that the question of whether animals can mentally time travel is not a purely empirical question. My argument hinges on premise (3): if psychologists have irreconcilable differences in opinion about which behaviors best express MTT, they will use the construct “mental time travel” to describe distinct phenomena and thus make different inferences from behavior to MTT. For example, if defenders of Uniqueness are using MTT as a label to describe a human autapomorphy3 but critics of Uniqueness are using MTT as a label for a core capacity shared with other animals, then they are clearly talking past each other and the debate is reduced to a semantic dispute about whether the term “MTT” is applied to “core” capacities or uniquely human traits.4 Therefore, I argue the empirical question of whether animals can in fact mentally time travel is intractable unless theorists can agree on both the connotative and denotative definitions of the term i.e. approximate agreement on the conceptual definition as well as agreement on its conditions of realization in the physical, measurable world.

1Chang does not analytically define the notion of “direct observation” but the paradigm case is observing the read-out of an instrument e.g. writing down the height of a column of mercury in a glass tube. Chang defends a hybrid version of foundationalism and coherentism whereby we begin scientific inquiry with some tentatively held beliefs justified by experience, especially the belief that we are capable of accurately observing the read-outs of our instruments.

2Citing neurological overlaps between “episodic-like” memory in non-human animals and human episodic memory, Corballis has recently dissented (2012). In his (2011) book, Corballis argues that what makes humans unique is our capacity for MTT and symbolic language super-charged by the capacity for recursivity i.e. Alice believes Bob desires that Chris thinks highly of Bob’s desire for Alice. Another recent convert is Roberts (2007), taking back his (2002) claims about MTT in animals.

3An autapomorphy is a derived trait that is unique to a terminal branch of a clade and not shared by other any members of the clade, including their closest relatives with whom they share a common ancestor.

4“We caution against grounding the concept of episodic-like memory in the phenomenology of the modern mind, rather than in terms of core cognitive capacities.” (Clayton et al 2003, p. 437)

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