The Reptilian Stare: Psychopath’s pupil dilation when you are the target

A reader asked,

. . . Having been a surviving victim of manslaughter at the hands of a registered psychopath (who had been in and out of jail since 14 years old and had murdered a man only months before becoming obsessed with me) I would welcome anyone to investigate into why the psychopaths “crystal blue” eyes turned death jet black, (like a sharks eyes).
I began nursing at 16 year old and am now 50. This is not the first time I have come across this anomoly.. . .

Good question!

I’ve wondered this myself, having been on the receiving end of what I would call psych-med-induced homicidal tendencies among my dear friends, neighbors, family and co-workers many years ago (ah yes, there were numerous product liability lawsuits on some of these, and I think they’ve been pulled from the market or restricted, thereby taking the ‘fun’ out of dys – FUN-ctional). (I kid).(What else can you do?)

Pupils dilate for all sorts of reasons, like seeing something you like, or being on narcotics. But, if you look at an animal with vertical pupils, their pupils get large and round when they’re zeroing in on a target.  That seems to me to be pretty close to the psych-med murderous look.  And behold: A recent paper reports that pupil dilation in response to target detection may be localized from a brain region deep in the brain stem, the locus coeruleus.   Privitera, C.M., Renninger, L.W., Carney, T., Klein, S., Aguilar, M., “Pupil dilation during visual target detection,” Journal of Vision 10:3 (August 6, 2010) doi:10.1167/10.10.3

This gets into the bowels of the brain, the reptilian brain, so to speak, to the roiling, evolutionarily archaic areas that operate in that primeval brew of neurotransmitters, heavy metals and glyco-fiber, the brain stem.  The locus coeruleus is, for one thing, blue, apparently, from melanin that is located in the substantia nigra radiating out. (For more explanation, here is a terrific Youtube neuro class, about 18 minutes. ) But, more to the point, this evolutionarily archiac little bundle of neural controls is key in how we respond to danger, or what we perceive as danger. Where the brain detects a threat, the amygdala and limbic system are activated and transmit signal to projections leading to the locus coeruleus.  The locus coeruleus, as the YouTube prof describes, spritzes the brain with norepinephrine for high arousal and vigilance. There are multiple other feedback loops as this area of the brain contains receptors that have been targeted by psych meds — many of which work to open and close chloride channels.

The wiring from the locus coeruleus goes up through the midbrain to connect with the amygdala and other areas. The brain midline defects apparently found in psychopaths (here) seem to provide a wide open highway for the reptilian signals .  Here is a brain with no septum pellucidium (where the red arrow is, there should be a piece of tissue) – one of the anatomical defects, apparently, in the psychopath brain (as it was defined at the time).

Lots of research has been done fooling with the septum.

Tragically, in infants and neonates, where the brain is underdeveloped including lack of a septum, the debilitation can be extreme, if not lethal. But, in psychopaths, the debilitation seems to be minimized as to basic physiological functions, perhaps because the other brain areas are more or less developed.

Fenestrating the septum (and defenestration gives me an attack of synesthesia, with sudden involuntary visuals of throwing the monks out the window, although it is confusing that fenestration is making a window, because then defenestration should mean eliminating a window, rather than going out of a window, but whatever), . . . fenestrating the septum in animals results in sham rage and all sorts of neo-reptilian behaviors.  (But see here, some guy had a septal cyst, and so microsurgery to fenestrate his septum made him feel better). Plus, the lateral septum has vasopressin and oxytocin receptors, and research points to these receptors, or rather the neurodevelopment of these receptors, being important for monogamous mating in voles.

So, if it is the case that the reptilian part of the brain catches the threat signal from the amygdala and then sends the limbic machinery signals of fear and loathing — and, the septum is not there to dampen any of this down physically or through the counter-veiling forces of vasopressin and oxytocin, then no wonder —  the reptilian stare.

Perhaps there’s a way to give psychopaths brain microsurgery (like the guy with the cyst, above) to put in a little piece of scaffolding seeded with stem cells or something that can act like a septum.  Other than that, because this seems to be pure neural wiring, maybe the thing to do is to distract them with some other sensory information, like a smell or loud noise or bright light.