世界顶级英语杂志1

28 SCIENTIFIC AMERICAN MIND Apr i l/May 2006 G E T T Y I M A G E S The founder of psychoanalysis was born 150 years ago, and in 2006 his theories are en- joying a rebirth. New life in- deed, because not too long ago his ideas were considered dead. For the fi rst half of the 1900s, Sigmund Freud’s explanations dom- inated views of how the human mind works. His basic proposition was that our motivations remain largely hidden in our un- conscious minds. Moreover, they are actively withheld from consciousness by a repressive force. The executive apparatus of the mind (the ego) rejects any unconscious drives (the id) that might prompt behavior that would be incompatible with our civilized ( FREUD at 150 ) His Infl uence Today Freud Returns COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. www.sc iammind.com SCIENTIFIC AMERICAN MIND 29 conception of ourselves. This repression is neces- sary because the drives express themselves in unconstrained passions, childish fantasies, and sexual and aggressive urges. Mental illness, Freud said until his death in 1939, results when repression fails. Phobias, pan- ic attacks and obsessions are caused by intru- sions of the hidden drives into voluntary behav- ior. The aim of psychotherapy, then, was to trace neurotic symptoms back to their unconscious roots and expose these roots to mature, rational judgment, thereby depriving them of their com- pulsive power. As mind and brain research grew more sophis- ticated from the 1950s onward, however, it be- came apparent to specialists that the evidence Freud had provided for his theories was rather tenuous. His principal method of investigation was not controlled experimentation but simple observations of patients in clinical settings, inter- woven with theoretical inferences. Drug treat- ments gained ground, and biological approaches to mental illness gradually overshadowed psy- choanalysis. Had Freud been alive, he might even have welcomed this turn of events. A highly re- garded neuroscientist in his day, he frequently made remarks such as “the defi ciencies in our description would presumably vanish if we were already in a position to replace the psychological terms by physiological and chemical ones.” But Freud did not have the science or technology to know how the brain of a normal or neurotic per- sonality was organized. By the 1980s the notions of ego and id were considered hopelessly antiquated, even in some psychoanalytic circles. Freud was history. In the new psychology, the updated thinking went, de- pressed people do not feel so wretched because Neuroscientists are finding that their biological descriptions of the brain may fit together best when integrated by psychological theories that Freud sketched a century ago By Mark Solms COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. 30 SCIENTIFIC AMERICAN MIND Apr i l/May 2006 something has undermined their earliest attach- ments in infancy—rather their brain chemicals are unbalanced. Psycho pharmacology, however, did not deliver an alternative grand theory of per- sonality, emotion and motivation—a new concep- tion of “what makes us tick.” Without this mod- el, neuroscientists focused their work narrowly and left the big picture alone. Today that picture is coming back into focus, and the surprise is this: it is not unlike the one that Freud outlined a century ago. We are still far from a consensus, but an increasing number of diverse neuroscientists are reaching the same conclusion drawn by Eric R. Kandel of Columbia University, the 2000 Nobel laureate in physiology or medi- cine: that psychoanalysis is “still the most coherent and intellectually satisfying view of the mind.” Freud is back, and not just in theory. Interdis- ciplinary work groups uniting the previously di- vided and often antagonistic fi elds of neurosci- ence and psychoanalysis have been formed in almost every major city of the world. These net- works, in turn, have come together as the Inter- national Neuro-Psychoanalysis Society, which organizes an annual congress and publishes the successful journal Neuro-Psychoanalysis. Testa- ment to the renewed respect for Freud’s ideas is the journal’s editorial advisory board, populated by a who’s who of experts in contemporary be- havioral neuroscience, including Antonio R. Damasio, Kandel, Joseph E. Le Doux, Benjamin Libet, Jaak Panksepp, Vilayanur S. Ramachan- dran, Daniel L. Schacter and Wolf Singer. Together these researchers are forging what Kandel calls a “new intellectual framework for psychiatry.” Within this framework, it appears that Freud’s broad brushstroke organization of the mind is destined to play a role similar to the one Darwin’s theory of evolution served for molecular genetics—a template on which emerging details can be coherently arranged. At the same time, neu- roscientists are uncovering proof for some of Freud’s theories and are teasing out the mecha- nisms behind the mental processes he described. Unconscious Motivation When Freud introduced the central notion that most mental processes that determine our everyday thoughts, feelings and volitions occur unconsciously, his contemporaries rejected it as impossible. But today’s fi ndings are confi rming the existence and pivotal role of unconscious mental processing. For example, the behavior of patients who are unable to consciously remember events that occurred after damage to certain memory-encoding structures of their brains is clearly influenced by the “forgotten” events. Cognitive neuroscientists make sense of such cases by delineating different memory systems that process information “explicitly” (conscious- ly) and “implicitly” (unconsciously). Freud split memory along just these lines. Neuroscientists have also identifi ed uncon- scious memory systems that mediate emotional learning. In 1996 at New York University, LeDoux demonstrated the existence under the conscious cortex of a neuronal pathway that connects per- ceptual information with the primitive brain structures responsible for generating fear respons- es. Because this pathway bypasses the hippocam- pus—which generates conscious memories—cur- rent events routinely trigger unconscious remem- brances of emotionally important past events, causing conscious feelings that seem irrational, such as “Men with beards make me uneasy.” Neuroscience has shown that the major brain structures essential for forming conscious (explic- it) memories are not functional during the fi rst two years of life, providing an elegant explanation of what Freud called infantile amnesia. As Freud surmised, it is not that we forget our earliest mem- ories; we simply cannot recall them to conscious- ness. But this inability does not preclude them from affecting adult feelings and behavior. One would be hard-pressed to fi nd a developmental TO M S T E W A R T C o rb is Patients may no longer lie on a couch, but many of today’s psychological counseling prac- tices stem from Freud’s early techniques. COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. www.sc iammind.com SCIENTIFIC AMERICAN MIND 31 neurobiologist who does not agree that early ex- periences, especially between mother and infant, infl uence the pattern of brain connections in ways that fundamentally shape our future personality and mental health. Yet none of these experiences can be consciously remembered. It is becoming increasingly clear that a good deal of our mental activity is unconsciously motivated. Repression Vindicated Even if we are mostly driven by unconscious thoughts, this does not prove anything about Freud’s claim that we actively repress unpalatable information. But case studies supporting that no- tion are beginning to accumulate. The most fa- mous one comes from a 1994 study of “anosog- nosic” patients by Ramachandran, a behavioral neur ologist at the University of California, San Diego. Damage to the right parietal region of these people’s brains makes them unaware of gross physical defects, such as paralysis of a limb. After artifi cially activating the right hemisphere of one such patient, Ramachandran observed that she suddenly became aware that her left arm was paralyzed—and that it had been paralyzed con- tinuously since she had suffered a stroke eight days before. This showed that she was capable of recognizing her defi cits and that she had uncon- sciously registered these defi cits for the previous eight days, despite her conscious denials during that time that there was any problem. Signifi cantly, after the effects of the stimula- tion wore off, the woman not only reverted to the belief that her arm was normal, she also forgot the part of the interview in which she had ac- knowledged that the arm was paralyzed, even though she remembered every other detail about the interview. Ramachandran concluded: “The remarkable theoretical implication of these ob- servations is that memories can indeed be selec- tively repressed.... Seeing [this patient] convinced me, for the fi rst time, of the reality of the repres- sion phenomena that form the cornerstone of classical psychoanalytical theory.” Like “split-brain” patients, whose hemi- spheres become unlinked—a situation made fa- mous in studies by Nobel laureate Roger W. Sperry of the California Institute of Technology A . W . F R E U D E T A L ., B Y A R R A N G E M E N T W IT H P A T E R S O N M A R S H L T D ., L O N D O N ( le ft ); O L IV E R T U R N B U L L ( ri g h t; a ll c o lo ri n g ) Freud drew his fi nal model of the mind in 1933 (be-low left; color has been added). Dotted lines repre-sented the threshold between unconscious and conscious processing. The superego repressed instinc- tual drives (the id), preventing them from disrupting ra- tional thought. Most rational (ego) processes were auto- matic and unconscious, too, so only a small part of the ego (bulb at top) was left to manage conscious ex- perience, which was closely tied to perception. The su- perego mediated the ongoing struggle between the ego and id for dominance. Recent neurological mapping (right) generally correlates to Freud’s conception. The core brain stem and limbic system—responsible for in- stincts and drives—roughly correspond to Freud’s id. The ventral frontal region, which controls selective inhibition, the dorsal frontal region, which controls self-conscious thought, and the posterior cortex, which represents the outside world, amount to the ego and the superego. Mind and Matter Posterior cortex Ventral frontal cortex Dorsal frontal cortex Brain stem COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. 32 SCIENTIFIC AMERICAN MIND Apr i l/May 2006 in the 1960s and 1970s—anosognosic patients typically rationalize away unwelcome facts, giv- ing plausible but invented explanations of their unconsciously motivated actions. In this way, Ra- machandran says, the left hemisphere manifestly employs Freudian “mechanisms of defense.” Analogous phenomena have now been dem- onstrated in people with intact brains, too. As neuropsychologist Martin A. Conway of Dur- ham University in England pointed out in a 2001 commentary in Nature, if signifi cant repression effects can be generated in average people in an innocuous laboratory setting, then far greater ef- fects are likely in real-life traumatic situations. The Pleasure Principle Freud went even further, though. He said that not only is much of our mental life unconscious and withheld but that the repressed part of the unconscious mind operates according to a differ- ent principle than the “reality principle” that gov- erns the conscious ego. This type of unconscious thinking is “wish ful”—and it blithely disregards the rules of logic and the ar- row of time. If Freud was right, then damage to the inhibitory struc- tures of the brain (the seat of the “repressing” ego) should release wishful, irrational modes of mental functioning. This is precisely what has been observed in patients with dam- age to the frontal limbic region, which controls critical aspects of self-awareness. Subjects dis- play a striking syndrome known as Korsakoff’s psycho- sis: they are unaware that they are amnesic and therefore fi ll the gaps in their memory with fabricated stories known as confabulations. Durham neuropsycholo- gist Aikaterini Fotopoulou studied a patient of this type in my laboratory. The man failed to recall, in each 50-minute session held in my offi ce on 12 consecutive days, that he had ever met me before or that he had undergone an operation to remove a tumor in his frontal lobe that caused his amnesia. As far as he was con- cerned, there was nothing wrong with him. When asked about the scar on his head, he confabulated wholly implausible explanations: he had under- gone dental surgery or a coronary bypass opera- tion. In reality, he had indeed experienced these procedures—years before—and unlike his brain operation, they had successful outcomes. Similarly, when asked who I was and what he was doing in my lab, he variously said that I was a colleague, a drinking partner, a client consult- ing him about his area of professional expertise, a teammate in a sport that he had not partici- pated in since he was in college decades earlier, or a mechanic repairing one of his numerous sports cars (which he did not possess). His behavior was consistent with these false beliefs, too: he would look around the room for his beer or out the win- dow for his car. What strikes the casual observer is the wishful quality of these false notions, an impression that Fotopoulou confi rmed objectively through quan- titative analysis of a consecutive series of 155 of his confabulations. The patient’s false beliefs were not random noise—they were generated by the “pleasure principle” that Freud maintained was central to unconscious thought. The man simply recast reality as he wanted it to be. Similar observations have been reported by others, such as Conway and Oliver Turnbull of the University of Wales. These investigators are cognitive neu- roscientists, not psychoanalysts, yet they inter- pret their fi ndings in Freudian terms. They claim in essence that damage to the frontal limbic re- gion that produces confabulations impairs cogni- tive-control mechanisms that underpin normal reality monitoring and releases from inhibition the implicit wishful influences on perception, memory and judgment. Animal Within Freud argued that the pleasure principle gave expression to primitive, animal drives. To his Victorian contemporaries, the implication that human behavior was at bottom governed by urg- es that served no higher purpose than carnal self- fulfi llment was downright scandalous. The mor- al outrage waned during subsequent decades, CO U R T E S Y O F O L IV E R T U R N B U L L Brain scans show the damage that causes disorders of psychological function, which Freud could study only clinically. A recent MRI image of a pa- tient who confabulates grandiose sto- ries of his life reveals a lesion (arrow) in the cingulate gyrus—part of the medial frontal lobe that serves func- tions Freud posited would normally prevent unconscious wishes from al- tering a person’s rational self-image. Freud himself anticipated the day when neurological data would round out his psychological ideas. ( ) COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. www.sc iammind.com SCIENTIFIC AMERICAN MIND 33 but Freud’s concept of man-as-animal was pretty much sidelined by cognitive scientists. Now it has returned. Neuroscien- tists such as Donald W. Pfaff of the Rockefeller University and Panksepp of Bowling Green State University believe that the instinctual mechanisms that govern human motivation are even more primitive than Freud imagined. We share basic emotional-control sys- tems with our primate relatives and with all mammals. At the deep level of mental organization that Freud called the id, the functional anatomy and chemistry of our brains is not much dif- ferent from that of our favorite barn- yard animals and house hold pets. Modern neuroscientists do not ac- cept Freud’s classifi cation of human in- stinctual life as a simple dichotomy be- tween sexuality and aggression, how- ever. Instead, through studies of lesions and the effects of drugs and artifi cial stimulation on the brain, they have identifi ed at least four basic mammalian instinctual circuits, some of which over- lap. They are the “seeking” or “reward” system (which motivates the pursuit of pleasure); the “an- ger-rage” system (which governs angry aggression but not predatory aggression); the “fear-anxiety” system; and the “panic” system (which includes complex instincts such as those that govern social bonding). Whether other instinctual forces exist, such as a rough-and-tumble “play” system, is also being investigated. All these systems are modu- lated by specifi c neurotransmitters, chemicals that carry messages between neurons. The seeking system, regulated by dopa mine, bears a remarkable resemblance to the Freudian “libido.” According to Freud, the libidinal or sex- ual drive is a pleasure-seeking system that ener- gizes most of our goal-directed behavior. Modern research shows that its neural equivalent is heav- ily implicated in almost all forms of craving and addiction. It is interesting to note that Freud’s early experiments with cocaine—mainly on him- self—convinced him that the libido must have a specifi c neurochemical foundation. Unlike his successors, Freud saw no reason for antagonism between psychoanalysis and psychopharmacol- ogy. He enthusiastically anticipated the day when “id energies” would be controlled directly by “particular chemical substances.” Today treat- ments that integrate psychotherapy with psycho- active medications are widely recognized as the best approach for many disorders. And brain im- aging shows that some talk therapy affects the brain in similar ways to such drugs. Dreams Have Meaning Freud’s ideas are also reawakening in sleep and dream science. His dream theory—that nighttime visions are partial glimpses of unconscious wish- es—was discredited when rapid eye movement (REM) sleep and its strong correlation with dream- ing were discovered in the 1950s. Freud’s view ap- peared to lose all credibility when investigators in the 1970s showed that the dream cycle was regu- lated by the pervasive brain chemical acetylcho- line. REM sleep occurred automatically, every 90 minutes or so, and was driven by brain chemicals and structures that had nothing to do with emo- B E T T M A N N / C O R B IS ( p h o to g ra p h ); A . W . F R E U D E T A L ., B Y A R R A N G E M E N T W IT H P A T E R S O N M A R S H L T D ., L O N D O N ( d ra w in g ) Freud sketched a neuronal mechanism for repression (above) in 1895, as part of his hope that biological explanations of the mind would one day replace psychological ones. In his scheme, an unpleasant memory would nor- mally be activated by a stimulus (“Qn,” far left) heading from neuron “a” toward neuron “b” (bottom). But neuron “alpha” (to right of “a”) could divert the signal and thus prevent the activation if other neurons (top right) exerted a “repressing” infl uence. Note that Freud drew gaps between neurons that he predicted would act as “contact barriers.” Two years later English physiologist Charles Sherrington discovered such gaps and named them synapses. (The Author) MARK SOLMS holds the chair in neuropsychology at the University of Cape Town in South Africa and an honorary lectureship in neurosurgery at St. Bartholomew’s and the Roy