Tag: brain

The neuroscience of fear

Continuing my interest in the neuroscience of emotion, I recently finished reading neuroscientist Joseph LeDoux’s book “The Emotional Brain”(*). This is a quick review and synopsis, in particular of those points relevant to psychotherapy.

LeDoux is one of the best known figures in the field, alongside Antonio Damasio, whose work I have also delved into, but found rather indigestible. Although I found Ledoux more readable than Damasio, I have two major gripes with the book. The main one is the title: there is not a lot in the book about emotions in general; Ledoux rapidly zeroes in on the single emotion of fear, which is his area of specialism. On this subject he is relatively enlightening, but it wasn’t what I expected or hoped for. In addition, some of the statements he does make about emotions in general, even if they may apply to fear are not obviously true of all emotions.

Additionally, the blurb suggests a book which is highly readable, but I did not find this to be really the case. It’s fairly readable, but has a tendency, especially in the later chapters, to get lost in detail. I would say it is not ideally pitched to the non-specialist reader (though likely at the same time to be oversimplified for a specialist), and does not belong to the best in science writing. Having been written in 1998, it is of course also somewhat dated by now, though I have not come across anything more recent.

LeDoux argues convincingly – but it is not very surprising – that there is no single “emotional system” in the brain, but we have to look at each emotion separately. As i said, he focuses on fear, which presumably is one of the easier emotions to study because it has a much longer evolutionary history than some of the “higher” emotions like love and joy which seem more particularly to relate to human experience. It is quite hard to read any conclusions across from fear to these other emotions.

LeDoux argues that we typically have little reliable insight into the factors which trigger our emotions, but a great tendency to make up stories about them and to believe in these stories. Indeed, we are unreliable in our reports of our emotional states as such. Emotions, unlike cognition, are intrinsically linked to the body and prompt bodily response; they evolved as “behavioral and physiological specializations” (p.40). The characteristic “feel” of emotions  reflect their different physiological signatures.

Emotions operate below the level of consciousness. This is illustrated by the phenomenon of “emotional priming” whereby the response to an explicit stimulus is influenced by a preceding stimulus the duration of which is too short for it to be captured in conscious memory (p.59). Mere exposure is sufficient; there is no need for any logical connection between the two stimuli.

The study of fear has, of course, a particular relevance to psychotherapy and some of LeDoux’s arguments bear consideration in this context, as he himself notes, though does little to develop. LeDoux argues that fear, and comparable emotions, are registered in the amygdala from where they govern programmed physiological reactions; at the same time there is a feedback loop to cognition which passes via the hippocampus. This latter circuit is obviously much more developed in humans than in lower mammals, but in all species it is notably asymmetric: the hippocampus, which is where new memories are created, has the equivalent of a broadband connection to the medial prefrontal cortex, but the available bandwidth is much less in the opposite direction. This, LeDoux argues, makes it difficult to reprogram the association made in the hippocampus between certain remembered events and the fear response. This sounds plausible, and may reflect experimental observations on the persistence of conditioned fear responses in rodents as well as the observed difficulties of therapy, but it is no more than suggestive of the conclusion which LeDoux draws.

Fear conditioning is the process which “turns meaningless stimuli into warning signs” (p.141). Some stimuli are preprogrammed: “laboratory-bred rats who have never seen a cat will freeze if they encounter one” (p.143). But most, of course, are learned. The simultaneous presence of two stimuli of which only one, the “unconditioned stimulus” (US) is intrinsically unpleasant is sufficient to form a link between them, on the basis of which the second or conditioned stimulus (CS) is subsequently sufficient to evoke the fear response, regardless of its intrinsic link to the US. This link is highly persistent and may indeed be impossible to forget completely even if, subsequently, no link between the stimuli is observed for a protracted period. The best that can be done is to extinguish it by presenting the CS repeatedly in the absence of the US, but there is always the risk of recurrence if relevant circumstances, such as re-exposure to the unconditioned stimulus, or simply a high level of ambient unrelated stress, arise. A CS may be almost anything: a place, a gesture, an expression, a tone of voice… Of course, the atomicity of these candidate stimuli is hard to determine : is being in exactly the same place necessary to evoke the conditioned response, or is it sufficient that a place bear some resemblance and, if so, in what respects?

In stressful situations, memory formation by the hippocampus is impaired. This would imply that traumatic events might not leave a memory trace, but still result in fear conditioning. In such cases, there may be no way to “reverse-engineer” the event out of the conditioned reaction. This has the clear implication that going after memories of traumatic events may be a fruitless strategy, and that resolution of trauma might happen without those underlying events ever being recalled, even if they occurred past the stage of childhood amnesia. However, the stress hormone cortisol has the opposite effect on the amygdala. Thus it is “completely possible that one might have poor conscious memory of a traumatic experience, but at the same time form very powerful implicit, unconscious emotional memories” (p.245). At the same time, recreating the emotional state conditioned does facilitate recall of explicit memories (p.212).

LeDoux’s analysis of conditioning and memory therefore sheds some light on problems encountered in therapy and on effective therapeutic strategies. I learnt something from  this book, but I suspect that a general book on recent contributions of neuroscience to psychotherapy might have gotten me more rapidly to my goal.

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(*) References are to the 1999 paperback edition published by Orion books.

John Sarno’s work on the etiology and treatment of psychosomatic disorders

I have been troubled all my adult life by disorders termed, which generally meant dismissed as, psychosomatic. These are disorders for which no physical etiology can be found, although they may have observable physical manifestations. From a psychological point of view, they have also recently been classified as somatoform disorders. As such, I was very interested to discover recently John Sarno‘s work on the subject.

Sarno’s basic premise is that just as emotional conflict can give rise to neuroses, so it also can give rise to pain and other physical conditions. This linkage may be direct, with Sarno positing that localized pain is a result of ischemia ordered by the central nervous system. Such emotional conflicts may also, via mechanisms which are presumably diverse, but which Sarno does not elucidate, result in afflictions to which non-psychological factors also contribute, whether in terms of their etiology or their clinical development. A key feature of Sarno’s posited diagnosis of tension myositis syndrome (TMS) is the variability in its lifetime expression. As such, it is an umbrella diagnosis or metadiagnosis for a variety of syndromes which have in common a non-progressive character. For a fuller discussion, read his 2006 book The Divided Mind.

I suffered in my early teens from clinical depression and situational urinary incontinence. By my mid-teens, this was replaced by muscular fasciculations, which I was convinced for a long time had to be a manifestation of a degenerative condition. Muscular function remained mechanically and electrically normal however, and much later this was officially classified as “benign fasciculation syndrome” (although it has receded, I am not fully free of it to this day). I went on at college to develop chronic fatigue syndrome, which at one point resulted in my being almost unable to walk. I also suffered at that time from migraines and back pain, and peri-orbital migraine was a regular occurrence for many years afterwards. During all this time, there have been no notable biochemical abnormalities observed.

Now I have not been monitoring bodily symptoms against my emotional state for many years and so I cannot provide a full account; it has changed immensely for the better, but I have still had my share of annoying things, in particular abdominal pains, and six or seven years ago Achilles tendinitis. Around May last year I developed plantar fasciitis on the left foot; it took a year to heel but then almost immediately the right foot developed the same symptoms. It has been quite debilitating as strenuous effort has tended to worsen it. All this led me to seek effective relief from the pain in various ways, a subject to which I will return.

Sarno’s notion, therefore, is very appealing. Indeed, given the importance of physical complaints, so called “hysterical conversion“, in the early development of psychoanalysis, it is not quite clear why attention has mostly been subsequently restricted to behavioral neuroses, especially outside of the Reichian tradition. Even if the mechanisms remain obscure, it is attractive to view psychosomatic disorders as somatic forms or expressions of neurosis.

However, I suspect the brain is less involved in mediating this relationship than we think. Sarno claims that the pain is directly generated by the brain as a diversion from unwanted emotions which threaten to break through into consciousness. I fancy this is otherwise: the brain is involved, certainly, in the repression of emotions, and by preventing their expression it prevents their discharge. The bodily symptoms, however, do not necessarily require neurological involvement and may arise on the basis of pure biochemistry. This is illustrated by research on the role of myofibroblasts in the mechanic regulation of connective tissue (see here). To me, the idea that the brain is busy, like some cranky old Wizard of Oz, devising ways to present consciousness with ever-new diversions seems crude, and it is not required to explain Sarno’s clinical outcomes. Variation in the site of pain may have simple biomechanical explanations.

So Sarno’s work is pathbreaking and liberating, definitively contributing to a shift in understanding of psychosomatic disorders, but it nonetheless needs to be taken with the necessary pinch of salt. Sarno offers, in The Divided Mind, no epidemiological data to back up his claim that the syndrome chosen by the brain is a matter of fashion (in a Kuhnian perspective, it is of course much more plausible that it is the diagnosis and corresponding collection of statistics which is driven by fashion, rather than the patient’s symptoms, especially since many of these diagnoses are evidently imprecise). He also offers no evidence to back up the conjecture that local ischemia explains the pain or that this is cerebrally induced (and if so, how). Indeed, the locus of pain is not discussed either, and some statements suggest Sarno does not have a deep understanding of myofascial biochemistry.

Sarno follows the usual path of airbrushing Reich out of the history of psychoanalysis, although it should be obvious that Reich was the first to look at the body and mind as a whole. However, his major error is to follow Freud’s mistrust of the id and misplaced trust in the superego. Freud, as we know, viewed repression as in many ways akin to a virtue upon which civilization depended. Sarno also paints a picture of the “childish, primitive” unconscious as the enemy within, even referring to it, with patent ideological bias, as the “dregs of evolution”, contrasting it to the “ethical and moral” conscious mind, a view hardly conducive to integration and well-being, and one which even Freud would have struggled to maintain (Nietzsche of course having demolished it comprehensively). His negative views of the moral quality of children are particularly depressing in their Calvinist overtones.

Several of Sarno’s statements in relation to brain neurology seem completely wrong: for example he attributes “rational, civilized” behavior to the neocortex, labeling it “that part of the human brain that has been added in the process of evolution”, even though the neocortex developed in the first mammals. The attempted equation between brain structures and Freud’s threefold division of the mind is presented as fact, whereas it is not a notion entertained by any mainstream psychoanalyst or neurologist. Indeed, Sarno oscillates gaily between the unconscious/preconscious/conscious model and the id/ego/superego model as if they were the same thing.

All this aside, this is a book which opened my mind to what now seems like an obvious fact but has long gone unnoticed, namely that the mind does not simply affect the body in vague, unspecified ways but perhaps in very specific ways where a direct link can be drawn between emotional circumstances and pain. It is pretty clear now to me what the circumstances were which led to both episodes of plantar fasciitis, and I am inclined to agree with Sarno that this knowledge is immensely emancipatory.