In today's last lecture, Al comments that

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Strangely, esthetic experience is given little attention by current students of the mind, yet this is one of the most central
aspects of the human experience [Santayana 1955]. Again such considerations suggest the importance of seeing the mind as an atom of cultural reality.
  ...
Strangely, amidst the current debates on the nature of consciousness, as neuroscientists and molecular biologists debate with transcendental psychologists and cultural anthropologists, one of the most significant aspects of human nature---the esthetic experience---is largely ignored.  Have we overlooked a key piece of the puzzle?
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The issues Santayana engaged are difficult for a scientist, but there is a related realm in which one would hope physiology could make a definitive contribution:  the understanding of pleasure and pain. Go to the medical library.  You will find far more written, complete with experiments, than you could digest in a long time.  But it is all on
pain.

What is its upshot, and how does it illumine our quest for some sort of understanding of consciousness? Hard to say. There are many curious observations, e.g., phantom limb pain, patented electrode implants that eliminate pain by periodic pulsing, existence of individuals who feel no physical pain (but still feel psychological pain), general anesthesia without chemicals (using AC current across the temples), the discovery of opium-analog neurohormones (but without understanding how that endorphin being in the right place corresponds to pleasure, than
ancient understanding that salt in the right place corresponds to pain). Not much that I can take away as "understanding" of pain, still less of pleasure, nor of the temporal asymmetry between them (there is chronic pain but not chronic pleasure).

What to do? A standard gimmick is to turn the problem on its head, to see if you can understand the opposite, and maybe that will delineate the original target, as though by visual contrast of an excluded volume. So we look for scientific works on "pleasure" (analogous to "beauty"), the opposite of pain.  Hmmm. Can't find much. "If you feed the subject 'stress' into a medical database, you get a printout 2-3 yards high.  if you put in 'pleasure' you get a couple of articles on
condoms and contraception." (attributed to Dr. D.A. Warburton, Head, Psychopharmacology, Reading University, 1995).

Let's be specific then, and look in the special places where one might expect expertise on some narrow topic under this category. The most acute conscious pleasure is orgasm. Is its neurobiology well understood, perhaps motivated by clinical needs (trauma affecting sacral nerves, side-effects of systemic medications, strokes, prosthetic repair of genital mutilation, circumcision, etc) ? There being at least 114 million human orgasms per day according to the Planned Parenthood Foundation, and probably several fold more, it is easy to find endless prose torrents in the non-technical literature (Cosmopolitan Magazine, Dr. Ruth, etc: about plumbing, technique, anecdote, etiquette, guilt, etc.) But what are the central nervous mechanisms, if any? (Some neurobiologists report finding nothing distinctly related in the CNS!)
What about illuminating aberrations of mechanism? The resources of the medical library provide some fragmentary scraps:

Erotic sensations are not induced by stimulating in the genital parts of the cortical somatosensory homunculus, but they are by electrically stimulating medial dorsal thalamus, medial forebrain bundle, or septal pre-optic area.

Chemical activation of the septum induces orgasm.

Some anti-depressants (fluotexine: Prozac) predispose some female users to unexpected spontaneous orgasm.

Some women can induce orgasm by stroking their eyebrows or pressing their teeth or waving fingers between eyes and Sun to make 5-10 Hz flicker;;

Some can do merely by thinking (which might provide an opportunity for fMRI scan during the experience, unpolluted by muscle artifacts).

Female quadraplegics sometimes experience phantom orgasm, akin to the phantom pain of missing limbs:  this would seem to suggest that some essential part the mechanism is not just peripheral.

Some also develop a patch of skin on the upper body innervated by transected nerves that formerly had sacral targets; stimulating this place on the torso induces orgasm.

Guanethidine can induce orgasm without the usual mechanical and ejaculatory concomitants in males; men with spinal column transected above Thoracic 11 are capable of all the ejaculatory mechanics but w/o experiencing subjective sensation.

Not only spinal nerves but also the vagus nerve and the hypogastric nerve seem indispensible for sensation.

Hypothalamic oxytocin seems importantly involved in both sexes, and in fact it is hard to find anything specifically male or female in this sensation, apart from the anatomical fixtures associated.

Orgasm records to the EEG as epilepsy-like activity in the septum and brain stem; it creates a fuss in the right parietal and right prefrontal (not the left??), and is said to require an intact corpus callosum; cingulate seizures can be experienced as orgasm.

Just as epileptic seizures can be induced by flickering lights in some individuals (15-20 Hz: remember the 700 Japanese kids who discovered that while watching a Pokemon video cartoon 17 Dec 1997), so can sexual pleasure be so induced in at least one individual: by waving the outstretched fingers in front of the sun. Is the efficacy of mechanical
vibration at some integer submultiple of 120 Hz (discovered by Victorian doctors for inducing "hysterical paroxysm" in women patients afflicted with "pelvic congestion" and "hysteria") more about central mechanisms or the mechanics of peripheral mechanoreceptors (Pacinian corpuscles?)?

One finds the most amazing experiments, eg in Pain 21, 357 (1985) that pain thresholds drop markedly while masturbating, and exceed all measured bounds during orgasm. Cerebral endorphin secretion? Is that chemical the actual source of orgasm, all that leads to it being basically a password?

I found only one explicit model (seldom cited) of a mechanism that might underlie some of these facts, and it is based entirely in the spinal column, and invokes "spreading depression" waves (which have no confirmed role in normal physiology).  Today a comparable interpretation might invoke nitric oxide or calcium-induced calcium-release
waves. Pertinent experiments have never been followed up so far as I know. Nor the connection, if any, the
CNS.

That's about it. John Morley says "Where it is a duty to worship the Sun it is pretty sure to be a crime to examine the laws of heat." It seems that for whatever reasons few enquire into the nature of the most familiar and dramatic conscious experience of pleasure and beauty, though it seems the ultimate purpose of so much human behavior and so
indirectly the source of so much corporate economic activity in advertising, movie production, etc to say nothing of talk shows.

Does anyone know a source for more coherent understanding?  Lots of questions await answers, any of which might lead to better understanding of consciousness, and "beauty" in particular, this being one of those rare topics which seem very close to the essence of consciousness, but almost completely unexplored:

Is its character much different in split-brain individuals? in particular, does the language hemisphere know of it only by report from the inarticulate right hemisphere?

Do any specific localized strokes remove the sensation? Or enhance it? Or alter it in other characteristic ways?

What brain centers (cortical? basal ganglia?  even cerebellar?) activate first in orgasm?  What is it about this electrical (or chemical?) activity that corresponds to "pleasure"?

What dynamic limits its duration, and what adjustable parameters affect that limit?  There is chronic pain, but no chronic pleasure: are they after all not opposite sides of one coin?

If orgasm (as opposed to mere ejaculation) can be induced by mood, arousal, etc with or without with specific tactile stimulation, exactly what are the necessary receptors? How is it that audio-frequency vibration serves much the same purpose as smooth stroking? What does the latter achieve at the level of dermal receptors? Is that the actual input to cerebral centers of awareness (if any such exist), or does the brain respond to something much transformed by pelvic sacral ganglia? Do bilaterally symmetric dermal receptors cross over to both sides of the brain? What is the needed stimulus when the cutaneous receptor has moved with reconnecting peripheral afferents to a non-genital site?

Is the subjective experience culturally determined, or much the same in all cultures? As far as the two sexes are concerned in our own culture, readers of verbal reports of orgasm cannot distinguish male from female
sources.  Is something of the kind common to all sexual species? certainly to all that masturbate (a surprising variety of farm and zoo mammals), but only mammals? only vertebrates?

Even if you are not laughing already, probably these will still prove to  be ludicrous questions when the first bits
of understanding come in. It is rare to find anything about which we know so little, even of the appropriate conceptual framework. But I doubt we will ever find any more powerfully non-verbal, non-computational inroad to the essence of "consciousness", unless it be pain. Pain being the more studied, I should think orgasm might provide a better fresh starting-place along the road of Beauty that Al remarks is so little traveled.
 

The few scholarly investigations I could find, dated after Santayana, none later than 1992:

"Olds,J.",1958,"Self-stimulation of the Brain", "Science 127, 315-324"

"Heath,R.G.",1963,"Electrical Self-stimulation of the Brain in Man",
"Amer.J.Psych. 120, 571-577"

"Heath,R.G.",1963,"Intracranial Self-stimulation in Man", "Sci. 140,
394-396"

"Heath,R.G.",1972,"Pleasure and Brain Activity in Man",
"J.Nerv.Ment.Dis. 154,3-17"

"Davidson,J.M.",1980,"The Psychobiology of Sexual Experience", "In: The
Psychobiology of Consciousness, ed. J.M.Davidson and R.J.Davidson,
Plenum Press, NY pp 271-333"

"Flor-Henry,P.",1980,"Cerebral Aspects of the Orgasmic Response: Normal
and Deviational","In: Medical Sexology ed. Forleo, R. Pasini, W.,
Elsevier/North-Holland Biomedical Press, New York, 256-262"

"Newman,H.F., Reiss,H., Northrup,J.D.",1982, "Physical Basis of
Emission, Ejaculation, and Orgasm in the Male", "Urology 19, 341-350"

"Faught,E., Falgout,J., Nidiffer,D., Dreifuss,F.E.",1986, "Self-induced
Photosensitive Absence Seizures with Ictal Pleasure", "Arch.Neurol. 43,
408-410"

"Tuckwell,H.C.",1989,"A Neurophysiological Theory of a Reproductive
Process","J.Neurosci. 44, 143-148"

"Bancroft,J.",1989, "Human Sexuality and its Problems", "Churchill
Livingstone, Edinburgh"

"Whipple,B., Ogden,G., Komisaruk,B.R.",1992, "Physiological Correlates
of Imagery-Induced Orgasm in Women", "Arch.Sex.Behav. 21, 121-133"

What more can you find, hopefully more on-target? Please tell me.

------------  new we follow the thread of repartee in this course:
Author:
Art Winfree
Date:
9:00AM, Tuesday, May 4 1999 (Week 15)
This replies to: Pleasure, Pain and Proxmire..., posted by Alwyn Scott on Tue May 4 00:24:32
( reminded of Senator Proxmire of Wisconsin: Golden Fleece Awards )
>>>My question: Do you think that this sort of constraint is still  limiting research along the lines that you have suggested?

Sure do! Certainly it inhibits _me_. For example, several years ago the notion  arose that the circadian clock (the 24-hour internal body clock that sharply regulates the ttiming of spontaneous wake-up, and more vaguely regulates onset of sleepiness in humans) gets reset by neurohumoral events, not only by external light and darkness. Conspicuous on  the list of such events is orgasm.... presumably .... but what is known of its actual CNS mechanism? This is what started me enquiring, and finding that nobody has any idea. But  back to sleep-wake timing: what's needed empirically is a "phase response curve" such as everyone measures in response to _light_ on every organism studied: the amount of phase  resetting as a function of the timing of the stimulus. If dead flat, this conjecture is dead. If nicely sinusoidal or with conspicuous features, it provides a first key to the mechanism of interaction. All we need is data from people recording what time they go to sleep and wake up,  and what time they experienced orgasm. There are many such people. Ask them. I planned this  survey with an MD in Montreal, using McGill medical student population. Then contemplating  newspaper coverage, Proxmire, the need to retain grants and credibility, etc I chickened out.  He rmained all for it (having cancer and expecting to die soon anyhow) but didnt go it alone, as I was the indispensible expert on human sleep timing. So whatever surprising discoveries this might have opened to human medicine (or at least the unsurprising result that there is no such interaction) at zero cost in lab equipment, federally funded salaries, subject
fees, etc ...  whatever, we don't have it. Basic reason: plain fear.