Pollack, Robert;
The Missing Moment: How the Unconscious Shapes Modern Science
Houghton Mifflin Harcourt, 1999, 240 pages
ISBN 0395709857, 9780395709856
topics: | brain | consciousness | clock | science
The control of time in the brain is posited as an important player in forming our awareness of the world, with a role in memory formation and other cognitive functions. The book completely subscribes to the so called 40hz theory, without revealing any arguments that may oppose it. The title is drawn from the missing half-second or so it takes for a sensation to register in consciousness - this half-second, the author posit, goes in forming a resonance of the sensation across the entire brain, the so called binding problem. The point is that just the sensation (say of a pinch), if transmitted to the brain just by itself, cannot produce awareness. Awareness involves binding this perceptual signal with a number of other associations - what a pinch at that point may have felt like earlier, is it painful, what actions should one take to respond to it, etc., These involve past memories and associations, and are controlled by neural circuitry quite different from the very specific tactile circuit that senses the pinch. So how are all these other circuits activated? The proposed answer lies in a wave that, originating in the thalamus, sweeps the brain from front to back, 40 times per second (40hz), drawing different neuronal circuits into synch with the precept, and thereby bringing the precept into the attentional foreground. If the thalamus is damaged even a little bit, this wave stops, conscious awarenesses do not form, and the patient slips into profound coma. This brings us to the subplot, revealed in the subtitle, of our unconscious. The half-second that elapses between the pinch on the arm to our awareness of it is used in marshalling this resonance, but the subject is completely unaware that there was any lapse. In the intervening period, neuroscientists may electrically excite the region of the sensory cortex corresponding to the arm, and the subject feels not the pinch, but an amorphous tingle. The brain is often unaware of many things going on (though these are pretty rare), and it is forever creating a consistent story of what the world is most likely to be. What will be attended to, and more importantly, what parts of the episodes and facts of life will be remembered, depend on many factors, particularly emotions, which are not determined by our conscious self. Thus many memories may be stored, but may be repressed, not available to the conscious self. These are providing a new impetus on Freud, and to psychoanalysis, many of whose ideas are coming into respectability again today. The book also spends some time dissecting the good from the bad in the psychoanalytical literature. In the end, Pollack tries to carry the unconscious analogy to our mental processes, particularly the way in which we do science. In the post-Kuhnsian, tradition, the scientist carries into his investigation all his emotions and prejudices... While the raw points are of interest, the writing is droll, and it takes too long to build up. The facts of interest - often significantly so - are scattered between too much else that is well-known and fails to interest. [blurb: ] All thought, even the most rational, is permeated with unconscious feelings, fears, and emotions. Scientists, like the rest of us, make choices for reasons they don't understand. The time has come for scientists and others to abandon the notion that there is any such thing as the disinterested pursuit of truth. Instead, they must strive for a therapeutic self-awareness of their unconscious agendas and work for larger goals than personal immortality.
Time's passage inside the head can be slowed, stopped, reversed, or sped up by the ticking of a number of internal clocks. Two very old clocks build the body from a single cell, a third drives the mechanisms of perception, another keeps us in synchrony w day and night, and still others cause a consc sense of the world and link it to unconsc memory. The inner times created by these clocks are multiple and complex, coming together only once at the moment death brings them all to stop.
The oldest and slowest of the clocks that build the senses is one we share w all other forms of life: the clock of natural selection, which continually builds new forms of life from old. Its beat is the birth of a species; millions of years may go by between ticks. One of its products is a second inner clock, a rhythm of signals that turn genes on and off in the cells of a developing embryo. The rhythm creates the senses as it builds a human body from genetically identical cells descended from a single egg. Present in all multicellular living things. A third clock is more restricted; it ticks only in nerve cells, welding the nervous system together with impulses arriving less than one thousandth of a second apart. These three clocks are deeply embedded in the past, and thus the senses are designed to meet the needs of species now long dead. Aristotle thought that a baby began when the semen mixed with urinal secretions and caused them to coagulate. In this way the man provided the baby's soul, life, and heart, and the woman its body. [Many scientists through at least the first half of the 19th c accepted this as fact. Source of cultural notions like families adopting father's name. ]
The new genome in a fertilized egg = archive of information.
Regulatory proteins (products of certain genes) attach to the opening
stretches of other genes in the genome, turning them on or shutting them off,
giving the cell a new protein or taking one away. When the new protein is
itself able to turn other genes on or off, it sets off a cascade of
gene-switching. The actions of these proteins, present only in the mother's
egg cell, make us "born of woman" in a second, deeper, way.
When developmental time begins for normal cells, the germ cells which are the
sole transmitters of the organism's genome, are left alone, undisturbed,
preserved for the next generation instead of being used up. In all other
cells of the body, the DEVELOPMENTAL CLOCK continues to open and close diff
genes in diff cells throughout a person's lifetime. For instance, sex
hormones are secreted by a small number of cells at puberty.1
Make two fists and bring them together to appreciate the rough volume and
shape of the human brain. Its unprepossessing appearance has led to many
deprecating descriptions; my favorite is the mathematician Roger
Penrose's: a bowl of porridge. In its two wrinkled, wet, warm hemispheres
lie chemical and electric circuits of the greatest known complexity and
density in the universe.
Only a third of the cortex is visible inside the skull, the rest is folded up
into the wrinkles. Nerve cells run in columns perpend to the sheet surface.
Within one cubic millimeter -- the size of a large grain of sand or a
rather small diamond -- the cerebral cortex contains about one hundred
thousand nerve cells. Each nerve cell makes tens of thousands of
connections to other nerve cells; the nerve cells in a sand grain of
cortex make about a billion connections with one another and with more
distant nerve cells as well. Connections from the cortex to distant parts
of the brain and spinal cord are wrapped in a fatty sheath called
myelin. Much of the inner part of the brain is called white matter because
myelin has a milky appearance rather than the gray of the cortex's nerve
cells
[gray matter = outer quarter-inch of cortex
white matter = inner part, mostly myelin from nerves interconnecting more
distant parts]
Behaviour of genes determined by environmental factors. E.g. amount of insulin hormone produced depends on how other cells respond to secreted insulin. Similarly, amount and extent of neural communication can affect the strength of connections between neurons. A network is estd when connections between a group become strong by gene activation. The almost simult arrival of impulses from many neurons activates genes in the recipient nerve cell, they direct the production of proteins that then hard-wire the cell into a network with the cells that sent the signals. This hard-wiring does not occur unless multiple input impulses arrive within a millisecond, as measured by one of the brain's internal clocks, the nerve cell's COINCIDENCE CLOCK.2 [about a bn cells, about 1K connections each ==> a quadrillion connections. If one was to solder these, could be many errors. Instead, the brain of a new-born is more richly connected - and these are then fine-tuned after birth. ] In the early embryo's brain there is a vast excess of weak connections among the nerve cells. As rough, even random clusters hook up to one another, the brain buzzes w cross-talk until impulses start to arrive simultaneously (within a millsec) - then these networks may harden the initial connection. Otherwise, the connection will dissolve. The size and complexity of a child's brain increases from birth till about the 10th year as the coinc clock continues to maintain an ever larger # of connections among nerve cells. Thereafter the connections tend to be winnowed, and the brain nerve cells begin to die for want of suff new connections. By late adolescence, the # connections is about the same as a 2-year olds; from then on they continue to decline slowly for the rest of life. A considerable portion of each brain's final circuitry is thus produced by experiences rather than genes. The eyes may see and the nose may sniff the air but the brain is in odorless darkness, its networks of nerve cells completely secluded inside the skull. Five centers deep in the brain unconsciously process sensory info so that it can become part of the consc recognition of the world. - thalamus (very base of brain, beneath the white matter and above spinal cord) - critical to consciousness since even the smallest damage to will cause profound coma - hippocampus - critical for memory storage - amygdala - emotional state - medulla - organizes subconsc movements like walking and breathing, which are optionally accessible to consciousness - cerebellum - a 2nd brain, like the navel of a "navel orange". Sits at top of spinal cord, behind and below cortex, takes signals from cortex and transmits directly down the spinal cord to the limbs to maintain steady, controlled movements. [muscle tone?] Is essential to movements involving conscious discrimination - is more active when picking up the correct change, than, say when grabbing a tossed ball.
Oldest, and reaches most directly into the brain. Early warning system. Fire. Bad food (can tell before nibbling). Tongue can taste only salt, bitter, sweet, and sour [blood, poison, calories, and unripeness]. All other tastes comes from smell. Sniffing or chewing : dissolves mixture of airborne chemicals and bring the solution to a space behind nose and above the palate - the retronasal passage. Olfactory epithelium - dime-sized carpet of about 10^7 nerve cells, each w its membrane covered by a specific odorant-sensitiive protein that can recog and bind to it. Proteins just inside the membrane respond to the binding by sending a elec signal along the nerve, which releases neurotransmitters that jump to other cells in the brain, which are themselves insensitive to odors but tells us that we have smelled something. There are many more perceived odours than the thousands of receptor [types] - various mixtures bind to subsets of diff receptors. Professional testers of perfume, coffee, etc. can distinguish among 10^5 diff odors, and any of us can tell 10^4. Mammals, each w no more than 60K genes in their chromosomes, give over at least 1K genes, almost 2% - to the coding of odor-recepptor proteins. The sense of smell was far more imp to the survival of our ancestral species than it is to us today. [Or is it? e.g. sexual selection?] Our germ line's inability to give up such a profligate commitment of genetic resources is an example of how natural selection differs from conscious design. During embryonic development each of the 10^7 odor receptor cells chooses from the thousands of odor receptive genes, and puts only that protein's receptor into its membrane. As the growing olfactory nerve then extends itself toward the brain, its choice of odor receptor protein determines who it binds to, eventually steering it to the same place in the brain. In this way, odor receptor cells are strewn about the olfactory epithelium not by patches each sensitive to a partic smell, but rather like a strewn meadow. The advantage of this developmental process is that the gene does not have to encode the connections (esp since it has already expended nearly 1K genes in the coding). The embryonic connections restructure themselves after the baby's first breath into meaningful odours... [AM: What of the chemical flavours in the amniotic fluid that is being gulped up?] Another small group of odor receptors have addl pre-embryonic function. Sitting in the membrane behind the sperm cell's DNA-packed head are a ring of odor receptor proteins. Recent work suggests that these are the helmsmen of the sperm, converting signals from the outside - molecules secreted by the egg, say, into a change in the direction of the sperm tail propeller... Rodent brains: second smell organ - the Vomero-nasal organ or VNO. Olfactory neurons of VNO run to a diff part of the brain which connects to muscular systems and is resp for diff activities. Odorants that cause an instinctive and stereotypical response are called pheronomes. It is clear than rodent pheronomes are acting through the VNO. The two major behavioural responses are a suckling response to milk and a mating response in the male when it comes from a receptive female. Humans have a rudimentary VNO behind the wall separating the two nostrils, but it is not clear whether it functions as a sensory organ or is just a remnant from some ancient common ancestor w the rodents. [Perfume makers are investigating chemicals that may affect this VNO, one of whose functions may be sexual stimulation. Even if a chemical w such extraordinary effects is found, it is unlikely to be consciously perceived as an odour since the VNO is not connected to the smell map in the brain.
Our developmental history ties our mental processes to operations in the dim
distant past. E.g. the way we perceive differences in colour is dependent on
the past as our sense of smell.
Newton's Opticks: w only prism and sunlight - seven colours as a celestial
octave [did this help him to see seven and not six or eight?]
Thomas Young [same man who deciphered the Rosetta Stone] - wave like
properties of light by passing them through two close narrow slits.
Concluded that colour vision is the result of nerves, each sensitive to a
diff part of the solar spectrum.
Retina: Three kinds of cones, but only one type of rod. The droplets of
light our rods and cones pick up can be very few and far between, sensitive
to very weak signals - 0.5 chance of perceiving a photon drizzle whose total
energy is < 10^-15 watt - about a candle seen from distance of ten miles.
10^8 rods - gray - in groups of ten - even if only one fires, brain gets
to know. .7 to 1.5 x 10^8 per eye
10^7 cones - colour - most are packed closely at center of retina, all but
missing in the periphery. 7 x 10^6 per eye
retina 150 mn receptors, but only 1mn fibers in the optic nerve
The range of frequences - about a factor of two from longest to shortest
wavelength - the very octave Newton intuited. By comparison, in hearing, at
least 7 octaves.
Hue, saturation colour: Most people can distinguish abt 200 hues, about 20
degrees of saturation for each hue. [Saturation = degree to which a colour
rises or sinks above the overall level of brightness of the surrounding
field). In all most of us see about 2x10^6 gradations of color.3
The retinal cells add and subtract the signals from the clusters of rods and
cones, and send the result of this computation odwn the optic nerve.
To prevent adaptation, the eye sweeps back and forth - driven by an unconsc
pendulum. Each rod and cone sends out a bkgd signal timed to the sweep of
the eyes. Though this sig reaches the brain, it may not reach consciousness.
The signal is also attenuated by the total strength of light - which is why
colours look the same in day or night.
This global renormalization is in place among our ancestors for the last 30
mn years. Without this conservation of colour we might go mad! [ Is the
colour really conserved in the hardware or in the smoothing function of
consciousness, or is there no difference?]
Three types of cones - short-wavelength receptor S sensitive to shorter half
of the octave (blue-end). med M and long L differ only by about 0.1
octave, covering green-red.
Substractive architecture. When long > med, recognize it as red.
M < L ==> green. Short is strong, and additive signal from other two is
absent ==> blue. S silent, L+M ==> yellow which is why we see yellow
when G and R is mixed, (and also as part of the direct spectrum). (L+M)
is active, and so is S ==> white. [we see white from blue + yellow]
The set of substractive / additive signalling was created many times. First
was millions of years ago. Colour film and TV also replicate it. 4
Colours are not smooth. e.g. can't see bluish yellow because it is seen as
white.
Mammalian colour vision: studied by Christine Ladd-Franklin. Most mammals
see colours, but even narrower range. Cone cells include S, but may lack a
third cone; only S and L. When a cat sees the sky, it will see a bluish
colour. But then if it sees a buttercup or grass or blood, it would see it
as a shades of something we can call non-blue. Old world monkeys and humans
have this 3d colour cell.
We don't know the details of all the genetic changes, but it is clear that a
gene encoding the L protein was accidentally copied twice, leaving one copy
next to the other in the X chromosome. In time the two identical copies of
the gene became different via mutation. The descendants of this primate
apparently benefited from some of the mutations, for within a short period -
a few mn years, new versions of these duplicated genes came about. Cone
cells expressing these two genes became the L and M cones.
The colors we see, and the ones we don't see - like the hundreds of colours
between B and G that we might have seen had the new third cone been more
shorter than M - are ancient choices made for us by selection. Because the
genes differed so recently, the L and M don't differ much. The wavelengths
absorbed by these two differ by only a few percent, and the proteins differ
by less than 1%.
The similarity of the two new genes also accounts for its instability. In
about 1% of female germ cells, one of the two copies is lost.
[wasn't this 8%?]
When that happens, a man is born w only two kinds of cone cells. Its usually
a man, because men inherit only a single copy of the X chromosome from their
mothers, while women inherit two. While this condition is called colour
blindness, it is really ATAVISM - a throwback to an earlier evolutionary
stage.5
[L: most sensitive to yellow-orange
M: most sensitive to greenish-yellow
red-to-yellow-to-green - > half the colours we see - is < half the
colour spectrum]
The RG distinction is so close, and yet we see plaids, Kandinskys, traffic
lights and so much else with it -
it is as if symphonies of music were being performed and perceiveed in
the range of tones fallinng betwen a B and its nearest B-flat. 35
shades of red-green may have helped our ancestor distinguish ripe fruit from
less ripe [or the fruit into ripening into diff colours, so their seeds could
disperse better!] Other animals, who saw only brown, were disadvantaged.
This is the heart of the book, where the "missing moment" is identified as a half-second or so when the brain integrates its stimulus with past memories and emotions to form a conscious awareness of its world and its internal processes. Libert's lab: patient lies with his brain exposed - but conscious. Arm is pinched. He says "ouch" - he thinks instantaneously, but actually about half a second has elapsed. The arm region of the brain is stimulated, if maintained for > half second, he feels a sensation, though it doesn't feel quite like a real pinch; more of a tingle. If pinched and then the electrical stimulation turned on within half-second, he wouldn't feel the pinch at all. When reversed, he reported the pinch first, and then a tingle. p.37-38 When is "now" for this patient, or for us? Role of the clock: the sensation of the pinch was in suspension for half-second; they felt instantaneous. When the electrical stimulation aborted this process, the time was still lost. Reflex arcs - some operate at ~ 0.1 sec - far faster than a second. Time used by brain to bring sensations together and merge them w memories and feelings is time forever lost to consciousness. It is also blending all the information received with stored memories and earlier emotional states. Only then does consciousness emerge, with its smoothly changing perceptions of both the outside world and the inner frame of mind. 41 conductor in charge of bringing the symphony of consciousness out of the brain's separate centers is a synchronizing wave of elec activity that sweeps regularly through the brain, from behind the forehead to behind the nape [back of neck], forty times per second. This 40hz wave links the centers of sensory info as well as other centers resp for unconsc and consc activities of the mind, particularly the amygdala, the hippocampus, and the frontal cortex, where broadly speaking, emotional states are generated, long-term memories stored, and the intentions to speak and act are generated. Our senses, words, behaviors, unconscious mental processes, and subjective conscious thoughts are a set of changes in neural networks. - p.42 Formation of the brain: first during embryonic development, by activating a set of genes whose products help assemble the embryonic brain, then by another set of brain-specific genes, activated by synchronization through the coincidence clock (1khz); then finally by the forty-cycle-per-second synchronizing wave. Behaviourists: study brain in terms of repeatable, measurable effects, i.e. behaviours. relegated choice, consciousness, imnagination as immaterial; Steven R. Harnad, psychologist: Only after the brain has determined what we will do does the illusion of conscious awareness arise, along with the mistaken belief we have made a choice or had control over our behavior. p.43 [Consciousness as an EPIPHENOMENON: position in philosophy that consciousness is a side-effect not connected to mental states (epi-= on, over, on the surface). Consequently, mental events (awareness), while they are real, are not the cause of anything, it is the brain state. ] Until 80s, hard to observe brain as a whole - hence many brain scientists agreed w Harnad. Coincidence clock - 1kHz - helps senses wire themselves to brain - but also to set up time-sensitive links between networks - allows each nerve cell in the brain enough time to particpate in many diff networks so long as each network synchronously fires its impulses at a diff instant. Circuits are linked through the coincidence of their signals. Requires a universal beat - 40hz "conductor" clock serves this purpose - visualizn of the brain's global patterns display a 40hz electical hum. A brain cell can belong to many diff networks, each working back and forth in a specific fraction of 1/40th second after the conductor pulse. Coupled w the capacity of nerve cells to tell time to the nearest 0.001 second, the 40hz hum unites the entire brain, sensory inputs, cortical centers of abstract processing, inner centers of emotion and memory, and signals to body muscles - all function together as a single organ capable of conscious thought. MOUSE WHISKERS: each whisker sends signal - how strongly it has been bent - to a vertical column of synchronously firing neurons in the cortex called a barrel. Normally the 5 rows of whiskers map neatly to 5 rows of barrels whose synchronous firing can be seen on the surface of the exposed brain. Touching one whisker generates electrical activity in the cells of precisely one barrel. WHen a mouse is deprived of all but one whisker, touching that whisker stimulates signals not just in its barrel, but in regions around it as well. One of the least attractive metaphors for the brain is that it is the hardware for the mind's computer. This comparison is usu made w the implication that as time goes by, computers will meet and overtake our brains, for they will expand in complexity and in their capacity to handle info while our brains remain stuck inside our skulls. It is a metaphor that severely underestimates the brain's plasticity. Though the nerve cells do not grow much after we are born, the connections are constantly re-formed. There is no brain "hardware" in the sense of permanent circuitry; the brain's "wiring" keeps changing in resp to the lives we lead. The brains of identical twins look even more sim than the brains of two unrelated people but the connections along the nerve cells in each twins cortex are far more diff than the ridges on their fingertips. When two people - even twins - think the same thought, diff sets of synapses are likely to mark that thought inside each skull. Because no two brains have te same setof experiences, it is unlikely that consciousness will ever be successfully modelled by hardware-driven technology, no matter how small, fast, or complicated. The 40hz hum was first detected by EEG, and then the magnetoencephalograph, (MEG) which can locate electrical changes spatially to the nearest cubic mm and can time these to milliseconds. The 40hz hum comes from two distinct clusters of nerve cells in the thalamus deep inside the brain. Each cluster is an autonomous oscillator, sending a 40hz wave along its extended fibers to all parts of the brain. Though the two thalamic clusters put out the same freq of background hum, each serves a diff function. The output from one allows the brain to bind together the ever-changing sensory inputs, the other sync's the brains internal workings. When the two thalamic oscillators work in synchrony, they bind the activities of the nerve cell networks tog in the centers of the brain resp for sensation with those resp for abstr thought, feeling, action, and memory, and consciousness emerges. Together the coincidence clock and the 40hz beats appear to moot the philosopher's mind-body problem, enabling the mind to emerge as an expression - a differentiated function - of the cells of the brain and the nervous system. The first thalamic cluster sweeps a 40hz wave from the front of the cortex, over our eyes, and its peak moves smoothly and swiftly beneath the top of our head, where the cortex is receiving info from skin and muscles, to the back and side regions where the cortex takes in signals from the eyes and ears. This first thalamic wave starts its sweep again every half-cycle, or at 80hz. Because the whole brain contributes to consc, intervals shorter than 1/80th sec cannot be consciously perceived. Because nerve cells in the brain communic in very short bursts that may (or may not) occur ever 1/40th sec, these bursts can be synch'ed by the thalamic wave, which is like the sweep of sunrise or sunset over earth - as the boundary of light and dark sweeps over the turning face of the planet, a longitudinal slice of people go to bed or wake up in phase w each other; same w nerve cells. Sensory data must be fused w the 40hz clock for signals to be meaningful. Diplopia: when the two eyes are not fused (e.g. muscles too weak to bring both eyes to bear on same object), brain sees two diff images. Experiments on kittens with prisms on eyes can prevent the two eyes from having any overlap. At first both retinas send info to the visual cortex in proper packages of 40hz pulses, resulting in a doubled image. But after some time, the cat brain dismisses one of the two images - for it to have any sort of useful vision, it permits only one channel to be synched w the cortex, and in the end the unused channel loses its connections to the cortex. Thereafter even if the glasses are removed the cat cannot see in one eye - it has lost stereo vision forever. In people as well, when one eye loses its sync early in life, the eye wanders in its socket, contributing nothing to visual awareness - AMBLYOPIA. I have had diplopia for decades - because each retina had been wired properly to my brain thru reinforced, coincidental signaling before my diplopia began, it can be corrected with prisms that cancel the offset and bring the two vis fields into register w one another - it is still odd when I take off my glasses and see two of everything - I never fail to wonder which is real. - 49,50 ATTENTION: When we hear a click, a very brief input from the ear nerves to the brain interrupts and resets the 40hz spontaneous sweep. For the next two and a half cycles, or about 1/15th of a sec, the entire brain's 40hz output is synch'ed to the input from the auditory nerves; in that period, we focus on what we hear, rather than what we are simultaneously seeing or smelling, because the auditory inputs synchronously interact with networks throughout the brain, binding the inputs of our ears to the rest of the brain, including the parts of the cortex that integrate, abstract, and name things. When two short clicks are presented less than 1/100th of a sec apart, we do not hear them as sep clicks because the 2nd click doesn't have the time to reset the 40hz wave again. Instead we hear a slightly diff tone, because both inputs are bundled into a single unit of perception, albeit one that is diff from that of a single click. Spoken lgs use differences in sound - phonemes - that last at least 1/100th of a sec - even the shortest diff e.g. that between the explosive beginnings of a p or a b - take at least that amt of time. When a language is learned well, this wave running through the brain integrates meaning without conscious effort. Until we have this facility with the lg, the reader is obliged to bring each sound or letter to full consciousness; this uses many more cycles of cortical clock, slowing down comprehension. The binding of the networks by two 40hz thalamic oscillators brings the more distant past of memory into every perception. The personal past also enters consciousness in the missing half-second described earlier - a small fraction of that is enough for the thalamic clock to synch to the sensation - and the addl time is used to establish a 2nd synchronization w the first thalamic sweep. Each perception we notice emerges only after this 2nd synch, which connects the sensory system to all of the brain - the cortex and the parts that carry past memories and feelings. Because the full processing of a sensation involves binding the sensory input to the cortical oscillations that represent memory, the brain never responds in precisely the same way to a stimulus, even when the stim is precisely the same. Expts on monkey's - signals from retinas alone cannot establish synch'ed connections between the vis cortex and other parts of the brain. Attending to a spot on the screen rather than the bkgd can reverse the output of a nerve cell in the visual cortex. "The cortex creates an edited representation of the visual world that is dynamically modified to suit the immediate goals of the observer." If either of the two thalamic clocks is damaged - by stroke, injury, or surgery -- a person loses consciousness and falls into a profound coma. When we are awake, the two thalamic clocks link the entire brain. At other times, when outside sensations are not being brought to consciousness - in a daydream, a dream, or fugue state - the 2nd thalamic clock's 40hz sweep continues to pulse through the brain, building and associating memories with one another, unperturbed by sensation. This is why dreams can seem almost real: both consciousness and dreaming use the same mechanisms. Consc integrates these networks with new sensory inputs, while dreaming uses sensory memories. A sleeping, dreaming person's brain is still processing, binding, and interpreting its own stored info, so the minimal time for the dreaming remains the same as when awake - about 1/100th of a second. But because the brain's work while dreaming cannot be updated by sensory events, dreams are free from the constraints of external time. The dreaming brain continues to link the cortical sweep with the phased outbursts of both the hippocampus and the amygdala, without responding to auditory clicks etc. In other, non-dream phases of sleep, MEG confirms that the 50hz waves do not sweep the brain any more. Awake, or asleep, the brain is "a closed system emulating reality as delineated by the senses," - Rodolfo Llinas of NYU Anesthesia: artificially induced state resembling sleep - mostly dreamless - disorganizing the 40hz sweep. other anesthesias block pain / paralyze muscles without interrupting the sensory or thalamic oscillators. In this case the patient may seem to be completely out of this world while she is actually fully conscious of what's going around, hearing and feeling the procedure. Sometimes anesth may result in a horrible state of paralysis while being fully conscious (and capable of feeling pain) - in such cases, a click may be administered and the 40hz wave checked to see if it resets. In Libet's patient, a pinch re-synched the oscillations, but the direct electrical stim didn't - so the latter failed to reset the brain by half a second - there was no missing moment. Perceived color or odors - or scientific data - are no different from the thoughts memories and dreams they bring about - all are inventions of the brain, aspects of its obligation to use the past in order to interact with the external world. Because consciousness is a full linkage of all the brain's parts through mediated by the two thalamic sweeps, its version of reality, filtered first through natural selection [brain architecture], and then through our own different, individual experiences, is the only reality any of us can know. The silent half-second the brain uses to mix new and stored inputs together with its own internal neural cross-talk also allows the brain to build the introspective models of past and future. The recent success of science in explaining how the brain binds multiple perceptions and memories into consciousness through the interaction of the 3 40hx timekeepers raises the q of how science itself works as an expression of brain function. Or, to what extent does scientific introspection depend on the unconscious memories of the scientist? - 55 Imagining - making models of the past and future with neither the benefit nor the burden of new sensory inputs - is just like dreaming. Stored past thoughts and experiences - memories - reappear in consc introspection, as they do in dreams. In each case, memory emerges as the brain reconfigures itself to meld neural rep's of past events with neural rep's of imagined events that may or may not reflect actual events at all. The second thalamic oscillator has no need for objective time. This is why the brain can compress a whole symphony or a brand new idea into what is a mere instant in conscious, objective time. This is also why time's passage has no fixed place in dreams. When the brain inner processes are linked by the second thalamic oscillator in the absence of changing sensory inputs, the passage of time cannot be registered. In his 1947 book, What is Life, Ernest Schroedinger famously predicted the structure of the DNA before its chemical composition was well understood by observing that the material carrying genetic info would have to have apparently contradictory properties - crystalline stability for the sake of stable inheritance, but also the capacity to change and exist stably in many slightly different forms for the sake of genetic variation. The genetic material would have to be an aperiodic crystal, and DNA is precisely that - with a stable scaffolding of two backbones made of alternating units of sugar and phosphate wrapped around a wholly informational, aperiodic sequence of base pairs. Synchronized networks of nerve cells in the brain would have pleased Schrodinger - they are aperiodic crystals of time. [draws this analogy over the next page] neural networks are aperiodic in time but stable in space; DNA is stable in time but aperiodic in space. Every scientist has a sense of her intrinsic capacity to be completely objective while creating models of nature based on sensory inputs - however greatly these senses may be enhanced by instruments. But that sense of objectivity is no more solidly based on the underlying reality her brain's workings than her sense of colour is based on the fair repr of visible wavelengths. In both cases, past [abstractions] pervade the present modeling of reality, attenuating objectivity.
Who controls the past, controls the future. Who controls the present,
controls the past. - George Orwell 1984
Without the selective recall of past events, the current moment is
incomprehensible. Memory precedes both language and self-consciousness, directly
aiding an organism's capacity to survive in a changing world. Folding the
past w perceptions of the present allows a creature to detect and focus its
attn on what is novel.
Memory for us is so bound in consciousness that we tend to overlook its
ancient origins and its ubiquitous presence in the animal world.
Among the centers of the brain that engage in unconsc mental activity are
those that maintain stable but untapped neural networks representing the
memories of all perceptions that hv neither faded away nor pushed themselves
onto our waking minds. By focusing our consc attn during a percepn event, we
sift our store of memories and bring some but not all to consc. it may be
recalled thus because it overlaps with the event, or because the feelings
evoked by a new event are similar to some past one.
Our emotional responses to an experience are as real a part of experience as
any direct perception, but they do not enter the brain through a sensory
organ. An emotional perception emerges into consciousness as a feeling; this
emotional content is called the "affect". Just as the brain can store a
perceptual memory, it can also store an emotional memory or affect. We
instantly and permanently bind the erotic, frightening, satiating,
fight-inducing and socializing affects of an event to our consc experience of
it - first immediately, and then in memory.
[AFFECT -- (the conscious subjective aspect of feeling or emotion)]
Memories w strong affects can be recalled by new but diff events that bring
on the same affect.
Embarrassing or awful contents of such memories makes consc recall difficult
to sustain. [didn't follow this line]
Novely gives an event an even higher chance of being retained in mem, but
when nov is assoc with intense affect, the retained mem stands a good chance
of then remaining repressed - maintained in the brain but kept from
consciousness - for an indef time, sometimes for a lifetime. One can argue,
since repressed
memories are not in the consc, that they don't exist. But the evidence of
both everyday life and clinical obsvn is that they do exist, because they can
and sometimes will come to consciousness unbidden in ways we do not enjoy.
[EXAMPLE would have been good!]
Selective memory and repression both reduce the informn load. Furthermoe,
repression is a necessary precursor to deception. The ability to lie to
oneselrf and dissimulate convincingly to others was no doubt an important
tool of pre-human relations ...
Earliest memories: infant brain includes repository of such unconsc memories
gathered while a newborn's consciousness is but a buzzing blur -
paradoxically, many of these emotions directed at parents are of fear and
anger - late breast or bottle, hug not forthcoming, harsh voice, etc.
In dealing with such situations, an infant's emotionally rich but
inarticulate mind can reach full consciousness only by passing through an
extended period of deeply felt but inarticulate emotional conflict,
simultaneously hating and loving the authority on which life depends.
Such ambivalence prefigures the awkward and painful way many of us deal with
similar concerns in adult life. We are reliving our earliest experiences
when we exercise these three survival mechanisms of the very young mind:
a) denial, deny that we have feelings of hatred towards someone in
authority or
b) when we convert the unacceptable love or hate we feel toward X into
the notion that X [also] feels this way about us, or
c) when we act as if we felt toward X the same way we wish X felt toward us.
we discover how to put away the pain of our real feelings, how to show a
cooler, calmer face to the world than we actually feel.
when all 3 defences fail may use fantasies. Unlike repressed memories, these
may emerge into consciousness as dreams or daydreams. When a daydream is not
suff to fend off repr memories or to contain an inexpressible wish, the wish
may also bring abt specific behaviours - obsessions - whose purpose is to
fulfill it. Obsessions may be trivial -- the need, e.g. to wear a certain
article of clothing at spl times - but they are vested w enormous emotional
weight. 64
Psychoanalysis - Abt a century back, Sigmund Freud came up w a series of
models that included - for the first time - an unconsc component to all
mental functions, including the rational ones that seemed least likely to
have any relation to the unremembered past. The strategies of psychoanalysis
subseq devised by Freud and followers have acquired a mystical patina.
Actually psychoanalysis is rather straightforward.
Clinical obsvn: Talking and listening carefully to a person's unguarded
ramblings can help him to safely and reproducibly bring painful and
embarrassing memories out of repression into consciousness; in the process
one also uncovers the hidden emotional connections between current and past
difficulties. The purpose is to help a person learn how to release the
past's control of present emotions, actions, and beliefs. Once the
underlying emotional connection of the past w the present is understood, the
emotional content of the current difficulty -- now understood in terms of
earlier events - can in many cases be brought under conscious control.
Recalled dreams are esp valuable in the analytic conversation. Without exptl
data to the contrary, one might reasonably discount dreams as a form of
useless and meaningless noise in the brain, perhaps the accidentally
remembered residue of a nightly cleaning out of the clogged-up memory
stores. This is not so in psychoanalysis: once the emotional affect of an
event is understood to be registered in memory, and once repression is
understood to be a directed action by the brain to keep certain affect-rich
memories from consciousness, dreams take on a new importance - meaningful
condensed outcropping of otherwise inaccessible, consc memories, and much of
analytical conversation centers on attempts to understand dreams in these
terms.
Psychoanalysis reconfigured the meaning of childhood memories forever. As an
infant grows into full consciousness, it learns to balance perceptual info
w remembered emotional affects - some memories reach consciousness easily,
others - partic of experiences and fantasies too painful, embarrassing, or
threatening, are either repressed or remain unconscious or they reach
consciousness in masked ways that lead to otherwise inexplicable behaviours.
The notion that a person's destructive, self-defeating behaviors and
disturbing dreams may be conscious manifestations of otherwise repressed and
unconscious impulses gave childhood itself an altogether new and somewhat
ominous aspect. Many turned away from psychoanalysis... but the
psychoanalytic narrative of the mind has withstood a century of scrutiny, and
remains a viable clinical tool to alleviate various self-destructive
behaviours.
clinical protocol that depended on the oddities of
analytic conversation - slips, pauses, free associations, and descriptions of
daydreams or nightmares.
Psychoanalysis spent its own childhood in fin de siecle Vienna.
Some of its earliest presumptions - e.g. a girl is
little diff from a boy without a penis, may be based on unexamined
repressions of late 19th c. Despite these self-referential flaws, the
model w a trinity of contesting, unconscious mental states:
id: reservoir of all motivation
superego: memory of idealized authority, setting the standards of allowable
thought and behaviour
ego: part of the Freudian psyche - unconsc result is a person's sense of
himself or herself.
Unconscious repressed memories are bridges between the sequential external
time and the inner brain's timelessness. 67
Freud in the essay "Creative writers and daydreaming" (1908): The relation
of fantasy to time is in general very important... Mental work is linked
to some current impression, some provoking occasion in the present which
has been able to arouse one of the subject's major wishes. From there
[mental work] harks back to a memory of an earlier experience (usually an
infantile one); in which this wish was fulfilled; and it now creates a
situation relating to the future which represents a fulfillment of the
wish. What it thus creates is a day-dream or fantasy, which carries about
it traces of its origin from the occasion which provoked it and from the
memory. Thus past, present and future are strung together, as it were, on
the thread of the wish that runs through them.
The ego, id, and superego do not map completely to curr maps of brain, but
unconsc matters of hunger, sexual desire, aggression, and fear occupy
portions of the inner brain, while outer, cortical regions behind the
forehead - deal with consc ego-like matters of subjective thought,
abstraction, lg, and planning. The unscons superego's world of values,
rules, standards, goals, rewards, and punishments is least ce1ntered.
work of Alexandr Luria on brain-damaged soldiers and civilians -
brain is functionally and anatomically divided into inner and outer parts.
boundary between these - limbic system - balancing acts of bringing together
the past and the present.
INNER BRAIN - unconsc processes, affects, memories
cerebellum, thalamus, hypothalamus (w the hormone-secreting pituitary
gland)
lies between the nose and the two bumps at the back of the skull that
mark the entrance of the spinal cord. receives chemical and
electrical signals; directs movements.
responsible for sensations of sleepiness, wakefulness, hunger,
satiety, thirst. general level of arousal, does not req conscious
intervention.
OUTER BRAIN - consc thought, perception, directed action, judgment
consc processing of signals from eye and nose, two wrinkled
hemispheres of gray cortex wrapped around a mass of white cables.
The white matter interconnects regions in the cortex and to the
LIMBIC SYSTEMS just beneath, and through them, to the inner brain
(incl the 40hz thalamic hum) [limbus = border]
Limbic systems store memories and generate erotic, fearful and
combative emotional states. Surgery that stimulates limbic regions
will generate a luminous recovery of old memories, rich hallucinatory
repertoire, and a constelln of vivid dreams.
Luria discovered that diff emotional affects radiate to the rest of the brain
from diff limbic centers. This clinical evidence was so redolent of the
phrenologist's discredited skull models that [this work was largely
ignored].
It was some time before Luria's observations were confirmed by scientists
working on drugs designed to alter a person's overall emotional response to
their experience. Many of these drugs bind tightly to cells of a single,
specific limbic region. The limbic pleasure center was rediscovered as the
major binding site for epoids, while another limbic center is the binding
site for the type of antipsychotic drugs that have the side effect of
reducing a person's interest in the world.
References : Ch.3
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Crick and C. Koch, Towards a neurobiological theory of
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(1992), pp. 153–159
Barinaga, 1992 Science 258:216, Brain remaps its own contours
Eichenbaum 1997 Science 277:330: How does the brain organize memories
Freud: 1907, Creative writers and daydreaming
1919, The "uncanny"
Greenwald+ Science 1996: Three cognitive markers of unconsc semantic
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Horgan 96: Sci Am v.172:106, Why Freud isn't dead
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Ian Gold
Does 40-Hz Oscillation Play a Role in Visual Consciousness?*1
Hubel, DH. Eye, brain, and vision, Scientific American Library, New York (1988).
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Eckhorn, R. Bauer, W. Jordan, M. Brosch, W. Kruse, M. Munk and
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