These questions follow naturally from the fact that most of a neurologist’s time is spent diagnosing, treating, and discussing the plethora of conditions that cause and are caused by damage to the brain. Whether resulting from ischemic, infectious, inflammatory or degenerative processes, the resulting clinical syndromes are both fascinating and depressing. And whereas the distribution of etiologies will differ from country to country, our common anatomy ensures that a similar scope of phenomenology will emerge from different pathologies. Despite the obvious differences between a mother in sub-Sharan Africa whose son is rendered aphasic from tuberculous meningitis, and a father in North America whose daughter’s personality is eroded by a brain tumor, their questions, fears and difficulties can be remarkably similar.

With regards to the resulting philosophical questions, it would seem that we innately¹ assume a dualistic position of sorts, taking a viewpoint that’s temporally and spatially unbound to that of our bodies. Haggard² notes, with regards to our actions, that a “ dualistic view of endogenous causation is engrained in our normal language”. This dualistic language is common amongst patients affected by neurologic illness, as well as their family members. Consider the difference between a statement like ‘my knees aren’t as reliable as they used to be’, and the comparatively absurd ‘my brain isn’t working as well as it used to’. The latter, when considered with anything other than momentary attention, should strike us as bizarre. After all, it has been an endeavor of neuroscience (not to mention other fields like philosophy, cognitive psychology and artificial intelligence) to explain how matter, or the brain in this case, results in the internal environment and our representation of self. The mind, being entirely dependent on the physics constituting the brain, can hardly refer to its constituting parts as ‘not functioning’ without at the same time saying that it is not functioning as it should.

This ‘benign dualism’ does have its advantages. The suspension of the belief that a loved one is nothing but an appropriately arranged constellation of atoms immediately creates a certain sanctity. Problems with the sanctity of human life notwithstanding, it does contribute to a worldview that we all prefer. As Dennett has argued³, the act of treating someone not only as a body, but as a ‘self’ that has a body helps preserve a ‘belief environment’ around things like death and birth, and protects individuals close to those stages. Whilst we might admit that this ‘center of narrative gravity’ is a fiction of sorts, it is a useful construct that informs our day-to-day behavior. Furthermore, viewing people ‘as brains’, or subscribing to a ‘brainhood’ that views people as ‘cerebral subjects’⁴, opens several philosophical wormholes. Perhaps justifiably, people fear that this view will result in fatalism, where concepts like free will and responsibility will be defunct, resulting in an unavoidable and irrevocable slide towards anarchy.

The issue is most dramatically played out in the legal system⁵. Here claims of criminality being the result of ‘organic’ pathology bring the issues of free will and responsibility into focus. If sufficient evidence tying someone to a murder is provided, the court has little choice but to find someone guilty and duly sentence them. But what if it is shown that the defendant has a brain tumor disrupting the pathways involved in moral reasoning and inhibition? Suddenly, it’s as if this ‘physical’ reason for the behavior removes the responsibility from the defendant. But surely there are physical processes underlying all of our actions? As neuroimaging improves, deciding where to draw the line will become more complicated.

More commonly, our unwillingness to accept that we are our brains, or at least a subset of thereof, is the reason behind the remarkable interest in cognitive neuroscience, particularly when it involves functional neuroimaging. Rarely a week goes by without a journalist reporting on a specific human quality or ability that has been found to correlate with certain brain regions. We hear of empathy being localized to the anterior cingulate cortex⁶, of romantic attraction activating the limbic system⁷ and of deception involving the prefrontal cortex⁸. But were our position on these things at all altered by these findings? Surely a difference in, for instance, emotional disposition between people would always have been dependent on a difference in brain function? The fact that we now have tools sophisticated enough to show the difference is still impressive, and the research has many interesting implications, but we didn’t discover a new fact about the mind-body problem.

This double-think we all partake in, where we view others and ourselves as being more than matter and physics, yet at the same time acknowledging that we can explain all observed and experienced phenomena in physical terms, lies at the heart of what makes neurology such an interesting and difficult field. In stark contrast to a patient whose heart is failing, the patient suffering from a ‘failing’ brain is suddenly confronted by the abovementioned philosophical conundrums. They can’t help but acknowledge that the illness isn’t just affecting ‘their body’, but that it is affecting ‘them’. As Alcauskas⁹ notes, neurological illnesses “dehumanize in a way that heart disease and renal failure do not.”

Despite the facetious safety our dualistic positions provide, whereby ‘we’ exist in a dimension unrelated to the mere physics of everything we observe, the neurological patient draws attention to the fragility of our being. A relatively simple physical process, like a clot becoming lodged in a vessel, can remove much of your brain and hence much of you. Your wife can be rendered a stranger, your taste in music may change, you may lose the concept of a ‘left side’. For those unfortunate enough to see their husband slowly change from the loving and caring companion to a paranoid and violent stranger, as may happen with frontotemporal dementia, the innocence and functionality of a dualistic view is unavailable, and insofar as we can provide physiological answers, these are wholly inadequate¹⁰. For us as physicians, in the first world just like in the third, these patients provide a constant reminder of the fragile relationship between the deterministic physical processes happening behind our eyes and everything we value.

References

1. Carruthers P. Cartesian epistemology: is the theory of the self-transparent mind innate? Journal of Consciousness Studies. 2008;15:28–53.

2. Haggard P. Human volition: towards a neuroscience of will. Nat Rev Neurosci. 2008;9:934-946.

3. Dennett DC. Consciousness Explained, 1st ed. London: Penguin Books; 1993

4. Frazzetto G, Anker S. Neuroculture. Nat Rev Neurosci. 2009;10(11):815-821.

5. Mobbs D, Lau HC, Jones OD, Frith CD. Law, responsibility, and the brain. PLoS Biology. 2007;5:e103.

6. Amodio DM, Frith CD. Meeting of minds: the medial frontal cortex and social cognition. Nat Rev Neurosci. 2006;7:268-277.

7. Younger J, Aron A, Parke S, Chatterjee N, Mackey S. Viewing Pictures of a Romantic Partner Reduces Experimental Pain: Involvement of Neural Reward Systems. PLoS One. 2010;5:e13309.

8. Abe N, Fujii T, Hirayama K, et al. Do parkinsonian patients have trouble telling lies? The neurobiological basis of deceptive behaviour. Brain. 2009;132:1386-1395.

9. Alcauskas M, Charon R. Right brain: reading, writing, and reflecting: making a case for narrative medicine in neurology. Neurology. 2008;70:891-894.

10. Adamo A. Of Minds and Maps. Neurology. 2009;72:1364-1365.

Of course, I don’t want to create the impression that science is clueless about epilepsy![i] But the condition has been one of the most difficult to characterize, and certainly to manage. It has been defined, historically, by its most dramatic signs – ‘attacks’, ‘convulsions’, ‘fits’, ‘seizures’ and so on. Often, but not always, in scenarios where these terms apply, the diagnosis is obvious. But as soon as one admits to the spectrum – from a mere lapse in consciousness to a never ending shaking and writhing that could end in death, the alternative diagnoses become plentiful, and differentiating them almost impossible at times[ii]. To take but one example, periods of excessive emotion and the behavior it led to resulted in Gower coining the term ‘hysteroepilepsy’. The diagnostic net has, over time, been cast too narrow (with epileptics often being accused of ‘faking’, or of being insane) and to wide (Jackson’s idea that ‘‘a sneeze is a kind of healthy epilepsy.’’)

Unsurprisingly, as our predecessors did with most things that were ‘strange’ or ‘mysterious’ (except when it involved their religion – there is certainly nothing strange about a woman turning into a salt pillar or the rivers of a city turning to blood), epilepsy was seen as something ‘non-organic’[iii]: at best it was seen as a ‘mental disorder’, but often the explanations involved evil spirits ‘possessing’ the victim.

But whilst the disease might not have a ‘demonic’ origin, it may justly be viewed as ‘evil’: to lose control and consciousness, often without any warning or provocation, and subsequently urinating, or biting your tongue, or aspirating, and then to awake, after hours of sleepy confusion, with a headache and muscle pains – it is something worth fearing. Furthermore, beyond the immediate ‘physical’ problems, there’s the stigma, the fear others have when the ‘attack’ happens, the limitation of occupational opportunities, the loss of independence, the fear of swimming or taking a bath…

As an aside, not everyone has a negative view of having epilepsy. Dostoyevsky, for one, seemed to look forward to his attacks (or rather, the ‘auras’ that preceded them):

” For several instants I experience a happiness that is impossible in an ordinary state, and of which other people have no conception.  I feel full harmony in myself and in the whole world, and the feeling is so strong and sweet that for a few seconds of such bliss one could give up ten years of life, perhaps all of life.

I felt that heaven descended to earth and swallowed me.  I really attained god and was imbued with him.  All of you healthy people don’t even suspect  what happiness is , that happiness that we epileptics experience for a second before an attack.”

Problems with assigning retrospective neurological conditions to famous historical figures aside, Dostoyevksy’s epilepsy is interesting for many reasons, and Mocost has done a brilliant job (as always) exploring them.

Anyway, further complicating matters is the plethora of underlying conditions that could present with seizures and fall within the ‘epileptic spectrum’. These range from focal areas of pathology to widespread damage or abnormalities, from big genetic abnormalities to single gene mutations, from the occurrence of a few seizures seemingly without any cause to a malicious syndrome or increasing seizures and cognitive decline. To think and speak of ‘epilepsy’ as an entity, or a well defined ‘set’ is a bit like suggesting that ‘sport’ refers to an entity or a ‘set’ – a group with things like curling, mountain climbing, chess, formula one, sailing, Unbeatable Banzuki and football in it seems rather arbitrary unless well defined ‘subgroups exist, which does somewhat negate the usefulness of the ‘parent term’. And we certainly don’t have well defined subgroups for epilepsy as we do for sport…

The (fictional) pretty face of epilepsy

Things became easier, but not easy, with the advent of electroencephalography, and characterizing seizures by their electric ‘fingerprints’ began. But people with epilepsy can have normal EEGs between seizures, and people without epilepsy can have abnormalities. More recently, both structural and functional brain imaging have furthered our understanding, and coupled with surgical advances, provide (some) patients with the hope for a cure. Of course, curing it without having to have a part of your brain removed in the process is the ideal, and progress is being made that could result in a implantable, ‘pre-seizure’ abnormality detecting device that could subsequently prevent the predicted seizure.

So, it’s not all bad news.

References/Further Reading

Edward H Reynolds, Ernst Rodin. The clinical concept of epilepsy. Epilepsia (2009) 50 Suppl 3 p. 2-7

And, what the hell, Garden State

As tends to be the case with any new technology, there are many who have their doubts. This ranges from the extremes of the anti-psychiatry movement, which continues to favour a “dualistic approach”, arguing that mental illness is a property of the ineffable soul, rather than an illness of the brain. Of this we shall speak no further, as it falls outside what this blog will generally consider to be valuable enquiry. Of considerably more value are the legitimate concerns of those who, whilst acknowledging that all psychiatric diseases possess an organic basis, question our ability to accurately ascertain these origins using present technology and methodology. William Uttal, in his book “The New Phrenology: The Limits of Localizing Cognitive Processes in the Brain” argues that we need to more clearly examine the limitations of modern techniques, furthermore implying that the current obsession with localisation is a form of “neophrenology” – or, other wise put, an echo of a once popular pseudoscientific practise, were conclusions about the state of development of specific brain areas were made based on the size of the overlying cranial bone!

Whilst I think that this claim (which is perhaps something of a caricature of Uttal’s actual thesis) is somewhat harsh, it is true that fMRI does have several limitations, which have been well described in the literature. What I wish to focus on in this piece is not the technical difficulties, but rather what I consider to be an inherent methodological problem in using fMRI as a diagnostic tool, which is perhaps the endpoint that is most hoped for by psychiatrists in cognitive neuroscience.

The first problem (which, incidentally, did not escape Uttal’s attention either) relates to weakness within the psychiatric taxonomy. Anyone who has closely followed the development of the fifth diagnostic and statistical manual of mental disorders will be aware of how much classification has changed (and will probably continue to change) within psychiatry. Until now, such classifications have been almost entirely based on phenomenological data, which has allowed us to group syndromes according to commonly occurring symptom clusters. These syndromes initially began as simple descriptions of mentally ill patients, and patients that behaved in similar ways were classified as having the same condition.  This lead to several errors, owing to the fact that several conditions, when viewed for a brief time, look largely the same – even experienced psychiatrists struggle to differentiate between the mania of a patient with bipolar mood disorder and the psychosis of the schizophrenic. Subsequently, syndromes were refined based on further assessment of age of onset, manner of progression and other longitudinal factors. Modern classification systems, such as the DSM-IV (diagnostic and statistical manual of mental disorders, fourth edition), use essentially the same criteria, albeit by employing enormous databases, pooled from studies conducted all over the world. Despite this, significant controversy remains, and most psychiatrists agree that we are some way from achieving anything like a “definitive” classification.

It is worth remarking how different this process is from what has happened in other fields. Take lesions of the cardiac valves, for example. Initially, they were probably also only described according to symptoms, which would have been largely indistinguishable from those of several other causes of heart failure. However, with the advent of instruments as simple as the first, rudimentary “stethoscopes”, one could directly observe the presence of heart murmurs, which could help determine not only the presence of a heart lesion, but, with some skill, the precise valve that was affected, and even the degree to which it was affected!

It is difficult to resist the temptation to suggest that fMRI will do for psychiatry what the stethoscope did for cardiology, but clearly things are not that simple. Going back to classification – psychiatry has a unique problem in that the vast majority of its conditions have been defined based on symptoms, rather than objective pathology. Again, compare cardiology, which has some syndromes (like heart failure, for example), but several diseases, which have been defined based on their anatomical origin and pathophysiology. This is crucial to successful treatment – two different valve lesions may present in the same way, but treating them in the same way is seldom appropriate. Few patients will appreciate an aortic valve replacement when the their disease is clearly confined to the mitral…

Is this the case in psychiatry? I would argue that we don’t know, but that we should probably try and find out before we decide how much diagnostic faith we put into neuro-imaging.  Evidence suggests that patients who present with symptoms of depressed mood, most of the day, every day, along with a prescribed number of other classic symptoms, can be classified as having “major depressive disorder”. This, in turn, can be regarded as a condition that is in most cases responsive to treatment with antidepressants and psychotherapy, either separately or in combination.

In recent years we have successfully described a range of findings, both on neuroimaging and neuropathological study, that appear to be common in patients with depression. Would it not then be reasonable to test patients for these changes, in order to determine whether or not they really have “depression”, rather than some other condition masquerading in its guise? How then, would we respond to such a patient? Would it be appropriate to deny them treatment? Would we label them as being malingerers? These could all be true, but another potential answer needs to be addressed.

When we begin to search for the neurological underpinnings of a disease, we begin with a syndrome. Assume we have a hundred patients with clinical depression on whom we conduct fMRIs, and so determine which features appear to be most common. Lets further assume the unlikely case that all of these patients have at least one or more finding in common, which will then form our new “definition” of what it means to have depression.

All we will really have done in such a study is to define one possible cause of a syndrome. As the case of heart failure and valve lesions have taught us – there could be several others. Perhaps even several of the patients in this study have developed depression due to a different mechanism, and only incidentally display some of the same findings as the rest of the group. And what of our patient? Who is to say that she herself is not the victim of some hitherto undescribed condition, causing her to develop the symptoms of depression on the basis of a unique neuropathological mechanism?

Things in psychiatry are not as clear as in cardiology (or gastroenterology or pulmonology or any other field in medicine for that matter). The functions of the brain are not intuitively elucidated from its anatomy, and although we must recognise that it is the starting point for all mental illness, it is not necessary to assume that it should form the starting point for diagnosis. Some would argue that a syndromic classification has its own weaknesses, a claim to which we must acquiesce – but is it not ultimately the method that would best benefit our patients, at least given our current knowledge?

If a patient comes to a psychiatrist feeling depressed, anhedonic and suicidal, she needs help, whatever might really be going on. A psychiatrist cannot claim that he only has a role to play when a “true” psychiatric illness can be detected – after all, if we are to fully reject dualism, we must acknowledge that even the most minor aberration of psychological function finds its origin in the brain, and since this is the organ we claim to treat, we cannot ignore it. It may sound like I completely reject the role of fMRI, and perhaps even biological psychiatry as a whole. But anyone who has bothered to explore my blog would see this is unlikely – indeed, I have dedicated an entire section to this subject. And next week, I hope to address the issue of treatment response. Here, we will perhaps be exploring an area where fMRI may truly come into its own, with potentially revolutionary consequences.

Across the Synapse

Alogia

(www.xkcd.com)

The natural response to this is to highlight an essential component of the exclusion – religious ideas are only excluded from being called “delusions” when they are out of keeping with the normally accepted behavior of the subculture. This, however, is not a complete solution, owing to several inherent ambiguities. Firstly, it is not always clear when someone has exceeded the norms of his or her subculture, especially in less extreme cases. A patient I recently saw comes to mind – she was a 19 year old girl who, together with her mother, had been diagnosed with folie a deux – a shared delusion. They were brought to the psychiatry clinic by the girls’ grandmother, who reported what she regarded as “over-religious behaviour”. Specifically, the mother and daughter would spend several hours in prayer each day, and engage in intermittent fasts as a way of showing their devotion.

Of concern in this case was the fact that the relevant subculture in this instance – a relatively small local denomination – did not regard this behaviour as abnormal. In fact, both the girl and her mother had achieved a degree of status through their devotion, and were regarded as something to which others should aspire. By definition, then, their behaviour should not have been regarded as delusional, despite the fact that both patients were becoming increasingly socially isolated, and had ceased to function effectively in any other aspect of their lives. As it happened, the diagnosis was made despite the positive views of their religious peers, and the patients were admitted for further treatment. They later showed signs of severe psychosis, and responded well to treatment. What this case illustrates, however, is the difficulty in relying on the views of the subculture in deciding whether religious ideas are “delusional” or not. Sometimes the most deluded are in fact the ones held in the highest esteem.

The concept of a shared delusion brings us to the second point of concern – specifically, the problem of a “mass delusion”. Again, I shall make my point by referring to a case. I spoke to the daughter of a patient who was being treated as an outpatient for paranoid schizophrenia. When I asked how her mother was doing, the patient replied that although she was still very paranoid, she at least seemed happy, owing to her involvement in a new church that had started in the area. This church seemingly placed great emphasis on “spiritual experiences”, including visions and prophecies. That a schizophrenic patient should feel comfortable in such an environment seems unsurprising – but what do we say of the rest of the congregation? If one of them were to have their first contact with mental health services, would their behaviour be regarded as normal, owing to its concordance with the rest of the subculture? Again, this could be inappropriate, as it could be that the subculture itself has become floridly delusional.

Making these distinctions are difficult, and can often involve exploring very sensitive territory. Personally, I find myself again struck by the ability of religion to confound and complicate, and can offer little insight into how best to approach these issues. Perhaps one day we can drop such an exclusion without totally sacrificing specificity. Until then, let us hope that those undiagnosed are able to achieve a degree of comfort within their specific subcultures – a not unlikely prospect given the enormous degrees of faith of which the mentally ill are capable.

The natural response to this is to highlight an essential component of the exclusion – religious ideas are only excluded from being called “delusions” when they are out of keeping with the normally accepted behavior of the subculture. This, however, is not a complete solution, owing to several inherent ambiguities. Firstly, it is not always clear when someone has exceeded the norms of his or her subculture, especially in less extreme cases. A patient I recently saw comes to mind – she was a 19 year old girl who, together with her mother, had been diagnosed with folie a deux – a shared delusion. They were brought to the psychiatry clinic by the girls’ grandmother, who reported what she regarded as “over-religious behaviour”. Specifically, the mother and daughter would spend several hours in prayer each day, and engage in intermittent fasts as a way of showing their devotion.

Of concern in this case was the fact that the relevant subculture in this instance – a relatively small local denomination – did not regard this behaviour as abnormal. In fact, both the girl and her mother had achieved a degree of status through their devotion, and were regarded as something to which others should aspire. By definition, then, their behaviour should not have been regarded as delusional, despite the fact that both patients were becoming increasingly socially isolated, and had ceased to function effectively in any other aspect of their lives. As it happened, the diagnosis was made despite the positive views of their religious peers, and the patients were admitted for further treatment. They later showed signs of severe psychosis, and responded well to treatment. What this case illustrates, however, is the difficulty in relying on the views of the subculture in deciding whether religious ideas are “delusional” or not. Sometimes the most deluded are in fact the ones held in the highest esteem.

The concept of a shared delusion brings us to the second point of concern – specifically, the problem of a “mass delusion”. Again, I shall make my point by referring to a case. I spoke to the daughter of a patient who was being treated as an outpatient for paranoid schizophrenia. When I asked how her mother was doing, the patient replied that although she was still very paranoid, she at least seemed happy, owing to her involvement in a new church that had started in the area. This church seemingly placed great emphasis on “spiritual experiences”, including visions and prophecies. That a schizophrenic patient should feel comfortable in such an environment seems unsurprising – but what do we say of the rest of the congregation? If one of them were to have their first contact with mental health services, would their behaviour be regarded as normal, owing to its concordance with the rest of the subculture? Again, this could be inappropriate, as it could be that the subculture itself has become floridly delusional.

Making these distinctions are difficult, and can often involve exploring very sensitive territory. Personally, I find myself again struck by the ability of religion to confound and complicate, and can offer little insight into how best to approach these issues. Perhaps one day we can drop such an exclusion without totally sacrificing specificity. Until then, let us hope that those undiagnosed are able to achieve a degree of comfort within their specific subcultures – a not unlikely prospect given the enormous degrees of faith of which the mentally ill are capable.

Jerome Siegel is a Professor at the Brain Research Institute at UCLA, and he has contributed tremendously to our understanding of sleep and dreaming. He wrote a review, published in 2008, where he asked this exact question. Before we get into the really interesting bits, I’d like to point out how much I enjoyed reading Siegel’s article. It’s well written, and has a certain cheek to it. The main point (to avoid killing you with suspense) is that the assumption that all animals exhibit a state recognizable as ‘sleep’ might not be as sound as many of us believe.  The article is divided into sections, each dealing with a class (more or less) of animals. Siegel gives an overview of the studies that have looked at ‘sleep’ in that class, which might come to ten or so articles (if that). Siegel then ends with a statement like:

There are more than 30 000 species of fish.

I cracked up every time.

A problem of definition

As I mentioned before, defining sleep can get tricky. And the problem becomes more and more obvious the further we venture on the evolutionary tree – recognizing sleep in chimpanzees is a lot easier than deciding whether or not an octopus is truly asleep. Whilst most animals that have been studied exhibit circadian changes in their alertness, this should not be confused with sleep. In fact, lesion studies of rats where the circadian control mechanisms have been destroyed didn’t result in reduced sleep.

So, we should be aware of circadian changes. We’d still be looking for a ‘rapidly reversible state of immobility and greatly reduced sensory responsiveness’, as Siegel points out. But this state needs to be homeostatically regulated if it’s to be deemed comparable to sleep as we know it. This, if you recall, means that we’d expect a ‘sleep rebound’ if animals are deprived of sleep. It’s worth noting that a further assumption of many scientists, and laypeople, is that enough sleep deprivation should be lethal.

On we go to the animals, looking for a state we can confidently call ‘sleep’.

Sleep deprivation in animals

The most famous of sleep deprivation studies is Rechtschaffen (which the internet tells me means ‘honest and upright’) and colleagues’ work on rats. Rechtschaffen is about as famous in his field as a scientist can hope to become. That is, unless they propose a novel view of consciousness which flies in the face of years of research and requires a slightly warped view of the universe.

What Rechtschaffen and co did is called the ‘disk over water’ technique of sleep deprivation. The results might be familiar to most, as they are mentioned in most textbooks when sleep is mentioned. The (poor and abused) rats developed a syndrome, characterized by increased body temperature and food intake, yet they lost weight rapidly. Furthermore, fur discoloration, skin lesions and (mercifully) death followed.

However, despite the fame generated by this research, it had some flaws. Firstly, the method of deprivation has been criticized, as it places an unusual amount of stress on the animal. Secondly, despite the flawed technique, pigeons were sleep deprived by the same means but didn’t show any of the abovementioned features. Thirdly, no other animals studied – as well as other studies looking at rats – demonstrated the same syndrome when deprived of sleep. Fourthly, and important for our species, humans don’t show even the earliest features of this ‘syndrome’ after 11 days of sleep deprivation.

Simple organisms and insects

No-one has lost their mind and claimed that bacteria sleep, but they have been shown to have circadian rhythms of activity. In a similar vein, cockroaches, bees and scorpions have periods of elevated arousal thresholds, but don’t meet (nearly) all the criteria needed for sleep. Drosophila, the well studied ‘fruit flies’, have been found to exhibit states that do meet all the criteria, though it’s difficult to comment on how analogous this is to our sleep-states, given that their neurochemistry and neuroanatomy (and so on) differs so much from ours.

Fish, amphibians and reptiles

Of the 30 000 plus, less than ten species of fish have been examined for sleep in laboratory studies. Those that have haven’t given us much to go on! Zebrafish have a resting state, but no rebound. The perch have a rebound inactivity after continuous stimulation, but this inactivity isn’t characterized by increased response threshold – they might just by resting after being continuously stimulated! Some coral reef teleosts (mean looking ray-finned fish) have continuous daytime and night-time activity.

Regarding amphibians, a certain researcher investigated two different species of frog, concluding that the one survives ‘only because they rest without loss of vigilance’, whilst the other (apparently) does sleep, despite showing similar behavior.

Reptiles will feature more heavily in future posts, but some species have been independently ‘found’ to have REM sleep, and to lack it.

Birds

Birds[1] have been studied in comparatively more detail, and show electrographic features of NREM and REM sleep. What’s really fascinating, is that migratory birds (like sparrows) show a seasonal drop in sleep of up to 60% during the migration period, even if they are kept in cages for those months. Furthermore, they suffered no ill effects, performing tasks similarly well, and had no rebound in the following weeks.

Land mammals

Closer to home, the mammals have been responsible for our current ‘definition’ of sleep. Or at least, of the 4000 or so species of land mammals, domesticated species like cats, dogs, monkeys and rats were responsible. The major problem, according to Siegel, is that these domesticated species were studied either in laboratories, or in their domesticated environment (zoos, mostly.) These artificial situations are devoid of predators, offer a stable source of food and don’t allow for seasonal migration. But those are rather mundane facts about sleep – certainly not what one wants to read about on a blog.

So what can the land mammals offer us? In short, some random facts. Let me explain. When I was on my fourth year elective, we saw a patient that lacked posterior communicating arteries. These as the vessels that connect the circulatory system of the ‘front’ of the brain to that of the ‘back’. Our professor of neurology looked at the scan and remarked something along the lines of: ‘oh look, no PComms! I hear the Mongolian gerbil often lack those.’ Instant amazement.

So, what interesting, ward-round enlightening sleep-related facts did Siegel point out? For one, whilst humans are the ‘most awake’ during REM sleep, the REM sleep of rats is their ‘deepest’ sleep phase. Whilst we humans secrete a load of growth hormone during non-REM sleep, dogs secrete theirs during waking. With regards to dreaming, several mammalian species do not show the cortical features of REM sleep, but rather have features isolated to the brainstem. This means we can be reasonable certain that the platypus doesn’t dream. But the best fact by far concerns erections. Humans have penile and clitoral erections during REM sleep, and so do rats. Armadillos, however, restrict their episodic tumescence to non-REM sleep.

Marine mammals

The rest of this posts pales in comparison to the section on marine mammals. Take the fur seal for starters. On land, its sleep seems pretty standard – both eyes are closed, there’s a reduced responsiveness and the EEG shows cycles of what appears to be non-REM and REM sleep. But in the water a bizarre sort of sleep shows itself: one flipper is active while the other is static, with corresponding closure of the one eye whilst the other remains open and with EEG recordings showing slow waves in the contralateral hemisphere only. It would appear, then, that half of the animal is ‘asleep’ – but can we even use that word? If the animal is swimming about, looking around? As if this all wasn’t too much to compute already, they don’t show much REM sleep at all, and after weeks in the water, no rebound in REM is observed.

What about the ‘most intelligent species on earth’, the dolphin[2]? One might expect the trend set by land mammals and land-water hybrids like the seal to continue, resulting in a state of no REM sleep. Perhaps this ‘sleep’ still alows the animal to swim, and come up for air, without decreasing their sensory awareness too much – we don’t want them to swim into things. And that’s what we find. You should, by now, feel rather uncomfortable labling this as ‘sleep’. To stress the point – if the animal can swim around, come up for air, never shows any EEG features of REM and still manages to notice a pending cataclysmic event before us, they obviously don’t show, or need’ the thing we call sleep. They’ve been found to remain vigilant, continuously, for more than 5 days, with no loss of accuracy. And some species never show periods of reduced activity. Ever.

Before we leave the dolphins, and end the discussion, they offer one more oddity. They do show slow waves on EEG at times, and these are always unilateral, like the seal’s. But they show symmetrical motor activity. And, most interestingly, they circle in counterclockwise in the northern hemisphere (and clockwise in the southern), regardless of the hemisphere showing slow wave sleep. Their ‘sleep’, it seems, has more in common with a hurricane than with ours.

Conclusions

Do all animals sleep? It seems unlikely, but it all hinges on the vagueness of our definition. Of the 50 or so vertebrate species (out of 60 000) that have been assessed for all the features of sleep we mentioned before, quite a number fell well short of the mark. The best answer, I suppose, would be one that acknowledges our severe lack of knowledge in this area – we simply don’t know.

I’ll end with Siegel’s last few lines:

It might well be more accurate to view sleep as a behavior whose presence, quality, intensity and functions vary between species and across the lifespan. Different animals have used sleep to maximize energy savings by reducing body and brain energy consumption, increasing survival by seeking out a safe sleeping site, releasing hormones and conducting a variety of recuperative processes. Some species appear to be able to accomplish these processes during the waking state. This view contrasts with the idea that sleep is a universal state with the same underlying vital function in all species.

[1] Incidentally, birds (or crows rather) are amazing. Watch CBC’s The Nature of Things episode on crows, titled A Murder of Crows. Breathtaking.

[2] If you haven’t seen Oceans, watch it, and when you’re done crying, help us stop the alleged second smartest species wipe out the first.

Main reference:

Siegel, J. M. (2008). Do all animals sleep?. Trends in neurosciences, 31(4), 208-13.

I’m sure almost everyone is aware of the fact that crows are ‘intelligent’, not just for birds, but for ‘other’ animals in general. They seem to have a fairly advanced social structure, for instance, and have the ability (it would seem) to learn from one another with greater ease than most birds. This got me thinking – how did they end up ‘playing’ their gliding game? Did one of them stumble upon it, with the other following suite? Did they both learn it from another bird? What does it mean to speak of birds enjoying something, or pursuing something simply because it is fun? What are the internal lives of crows like, and is it the same for these two crows as it is for all crows?

My love for crows is, to some extent, a feature of my love for nature. I am all too aware of humanities effect on the planet, on other species, and so on. But I’m also aware of our place in a greater scheme of things, a tree of life, having journeyed as far as other species alive today. My consciousness has been raised in this regard, I am less inclined to take up a in-group out-group stance towards other animals. I felt moved by the crows, intrigued, and awed. It is as if I’m running an operating system with a biology ‘hotkey’, with easy access to the facts and data that would lead to a more ‘naturalistic’ and ‘don’t harm the animals’ outlook.

Consciousness as a collection of programs (in the metaphorical sense of course) leads to some interesting implications. To illustrate this, we can set up a (false) dichotomy – either consciousness is entirely innate, meaning that all Homo Sapiens (or Sapiens Sapiens), regardless of their childhood, will be conscious, or it is entirely learned, a function of the social interactions and such. What do these extremes illustrate? The innate ‘wing’ proposes a view not dissimilar from the traditional view of consciousness, in that it was thought to involve a ‘soul’. God gave everyone a soul, apparently, and consciousness or conscious behavior was the result. Whether this all-or-nothing view involves a soul or simply a specific neuroanatomical group of units doesn’t matter (today at least), what matters is the all-or-nothing nature of this view and, as a result, the fact that all humans are conscious and conscious ‘to the same extent’.

The learned ‘wing’ would be forced to acknowledge that there can be ‘levels’ of consciousness, not in the medical sense (at least not only in that sense) but in the phenomenological and philosophical sense. Someone who lives in a highly social, stimulating and intellectual environment, for instance, could be ‘more conscious’ than someone who was raised by chimpanzees.

As is often the case, the truth likely resides somewhere in between. Except for the bit about a soul – that’s exceedingly unlikely to play any part in anything. If consciousness is a feature of the protons, neutrons and electrons in our brain, it means that it must result from some ‘minimal’ subset of physical structures. By this I mean that, it is possible to have a ‘minimum’ of requirements before a person is declared conscious. This could involve both distinct anatomical structures, which would likely develop in all humans, as well as a specific set of neural connections or pathways which could be influenced by the environment during childhood, for instance. The specific neural connections and ‘software’ could be the result of a combination of nature and nurture, or genes and memes. This seems likely, given the ‘recent’ evolutionary appearance of consciousness. And this is the view that modern neuroscience generally holds. As one can see, it’s much closer to the ‘learned’ extreme, leaving the possibility of ‘levels’ of consciousness open.

I’m sure that the proposition of differential awareness doesn’t go down well with everyone. To suggest that a professor of physics at Oxford University is more ‘consciousness’ than a young hunter in a Khoi-San tribe is surely going too far, you might exclaim. But why wouldn’t this be the case? If consciousness develops during childhood (and, to an extent, in later life) like language or abstract thinking, why wouldn’t there be a difference? I realize my example is decidedly colonially biased, but it is simply an example.

As I mentioned before, a lot of the details depend on what is meant by ‘consciousness’.  But part of the definition usually includes an awareness of the outside and internal world, and an ability to have subjective experiences related to these worlds. It is something I’ll blog about in the near future, but seeing consciousness as something that develops, something which does not necessarily result purely from our being Homo Sapiens, has interesting implications, both ethically and intellectually. To admit that our internal lives, our propensity to be aware of the minds of other people, our insights into the workings of our minds, and so much more, is not present in equal measure in all humans is a fascinating concept.

And, in my opinion, it is an inevitable conclusion given what we know about the human mind. Your response to those crows might have been decidedly different from mine, but both of our phenomenological worlds might differ so much more from illiterate humans, for example,  that we might, if push would ever come to shove, have different ethical considerations towards them than towards one another.

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