Reason Depends on Body and Brain

by Dorothy Tennov

From a review of Descartes' Error: Emotion, Reason, and the Human Brain by Antonio R. Damasio, (Avon Books New York, 1994) in the Newsletter of the European Sociobiology Society, March, 1998

Long ago, as an undergraduate participant in a psychology experiment, I was presented with a series of pictures at durations too brief to allow me to identify their contents. To the one that stands out most vividly in my recollection (or "reconstruction") I gave an emotional reaction of such intensity that I drew in my breath audibly and brought a hand to my mouth. Yet I did not know what I had seen. Later, when the same pictures were presented at longer durations and I could clearly see the one to which I had reacted so strongly, I was astounded by the appropriateness of a reaction mediated by processes entirely beyond my consciousness. Similarly, when I was presented with three sounds in a perception experiment and required to indicate whether the third was more like the first or more like the second when they all sounded the same to me, I could only make wild guesses. But my responses fell neatly along a curve; my guesses were under the control of stimuli undifferentiated to my awareness. Today, priming effects and other confirmations of control through unconscious processes are well-documented, but no written report can quite match the personal reactions I felt in those controlled situations. Nor have the implications been adequately incorporated into common conceptions. We think of ourselves as acting consciously and although , if pressed, we admit that we do not exactly control the genesis of our ideation, we still feel that consciousness, not unconsciousness, is where things happen. Antonio Damasio's Descartes' Error: Emotion, Reason, and the Human Brain presents a conception of mind that moves us closer to a conceptual reality that incorporates it all -- conscious processing, unconscious influences, the emotions, and, as Damasio adds with scientific flair, the body in all its varied parts.

Descartes' Error (1994), is a very successful book written by a very successful scientist. It has been translated into a dozen languages, featured in major popular magazines, and its author has appeared on national radio and television shows. Furthermore, and of greater significance, it has received high praise from colleagues in the scientific community. As it contains a major scientific, social, and personal-philosophical message banishing forever the dualism of former times and setting conceptions of human mentality on a new course in the popular as well as the scientific imagination, it clearly deserves all the accolades.

Descartes could not conceive of thought as physical. His intuitions decreed that the mind must be some magical, mysterious, non-body mental force that is inherently different from mundane physiological functions. Nor could previous scientists who lacked accurate conceptions of the time scale on which evolutionary processes operate conceive of the complex and intricate processes arising by natural, physical laws. It is not that Damasio is the first or only theorist to put forth a neurolgically-based conception of the mind. Luria, Sacks, Penfield, Hebb, Edelman and many others also reject the traditional Cartesian notion that mind is an ineffable, mysterious, supernatural extra-body entity and view the problems of consciousness and of self as within the reach of concrete scientific investigation.

For most of the 20th century, scientific psychologists, mired in the concept of objectivity as the requisite for materialism, virtually outlawed discussion of mind. They focussed, as much for ideological as for scientific reasons, on the experimentally manipulable and directly observable. Now, neuroscientists use the powerful tools of magnetic resonance imaging (fMRI) and positron-emission tomography (PET) that permit direct observation of neurological processes. These, supplemented by computer-assisted analyses, e.g. Brainvox, enable the relating of specific functions and dysfunctions to specific sites of damage. It had seemed at first that the brain functioned as a memory storage vessel, a view bolstered by Penfield's finding that stimulation of parts of the brain elicited reports of what appeared to be vivid recollections. This conception has now given way to one of multiple modules and recurrent loops in a ceaselessly active nervous system. Construction and reconstruction, not storage and retrieval, better describe the process. The current image is one of multiple and complex interrelations among various cortices and pathways of simultaneous feedforward and feedback transmissions including numerous interconnections across the cortex.

For purposes of analysis, Damasio divides the organism into two parts: body proper and brain. Brain refers to all parts of the nervous system, even including the neurologically stimulated passage of chemicals through the blood stream. The rest is body. The key conception, the one at the heart of Damasio's dynamic conception of mental (brain-body) functions, the one that guides experience and behavior, is the largely unnoticed or nonconscious operation of the interplay between the cognitive processes involved in planning and decision-making and the "feelings" induced by bodily changes. Experimental neuroanatomical findings and human neuropsychological data suggest that the decision-making network includes bilateral ventromedial prefrontal cortices, right somato-sensory cortices, and autonomic-endocrine nuclei such as the amygdala, hypothalamus, and brain stem. Some processes and reactions, especially those necessary for the regulation and maintenance of the health of our physiology, are innate, but the vast majority are developed during the life span through interactions with the pains and pleasures experienced as the result of environmentally mediated events.

Damasio begins with the amazing and unexpected relationship between frontal lobe damage and the specific (yet seemingly general) change such damage produces in the personality. Why did Phineas Gage, Damasio's patient Elliott, and other victims of ventromedial lesions, fail to plan and to carry out personal life decisions even while they functioned normally on virtually every psychological measuring instrument with which they were confronted? Localization of language, vision, and other functions had been determined in that certain brain area damage was associated with specific dysfunction, but the deficit produced by frontal lobe injury was not picked up by standard intelligence, perception, or personality tests. Yet these patients cannot manage their lives. They neither make the decisions and nor carry out the plans on which survival depends; they fail at every enterprise. The implication seemed to be that there was a specific and localized mental module involved in these major life-governing functions. A better answer developed when it was noted that Elliott displayed little emotional response, especially of what Damasio called "secondary," the kind that develops through association with innate emotional reactions. Elliott himself remarked that before the brain tumor he had felt sensations and emotions that he no longer experienced.

This spark set Damasio's theory-building apparatus into motion. The prefrontal cortex receives input from sensory areas, somatic areas, association areas, and parts of the limbic system, an area associated with basic drives and emotions. What then was damaged by frontal lobe lesions? Feelings. Emotional responses. From this, Damasio constructs a plausible conception of reasoning and its dependent relationship to emotion and experience in the normal organism.

Brains evolved, Damasio reminds us, to enable bodies to survive. They monitor constantly. Emotions result from threat, from the prospect that bad things will occur to body. As William James noted a century earlier, emotions are notably body. Throats tighten, muscles tense, heartbeat patterns change, perspiration flows, capillaries dilate or constrict. These and many other body functions are intimately tied in with the ever-active conscious and (largely) unconscious mind. When favorable or unfavorable events occur, the body and nonconscious mind remember. When a similar event is later anticipated, "a disposition" occurs in response to a feeling that may be consciously experienced or may only exist as a neuronal pattern or image. That "somatic marker," which may have been given innately or acquired through similar past experience, gives rise to a process that says go ahead in one direction or turn to another. The decision process is affected in that at each choice point, when innumerable possibilities lie before us, our learned or innate, present or symbolic, body sensations push unpromising possibilities out of consideration, leaving only a few for consciousness to evaluate in working memory, that tiny tip of the iceberg in which reside our senses of self and of control. When patients suffering frontal lobe damage that caused this mechanism to have been disconnected are asked to make a simple decision regarding, for example, the time of their next appointment, they might, as Elliott did, spend an agonizing period considering all sorts of reasons for and against various possibilities. They lack a mechanism that enables them to choose.

Damasio's conclusion is that emotions are essential to rational thinking. Far from interfering with rationality, the absence of emotion and feeling breaks down rationality and makes wise decision making impossible. The widely held view that there exist separate neural systems for reason and emotion is no longer tenable. As Damasio says, "Flawed reason and impaired feelings stood out together as the consequences of a specific brain lesion, and this correlation suggested to me that feeling was an integral component of the machinery of reason." And reason depends on several brain systems, working in concert across many levels of neuronal organization, rather than on a single brain center. Both high-level and low-level brain centers, from the prefrontal cortices to the hypothalamus and brain stem, cooperate in the making of reason.

Quoting Damasio directly: "The lower levels maintain direct and mutual relationships with virtually every bodily organ, thus placing the body directly within the chain of operations that generate the highest reaches of reasoning, decision making, and, by extension, social behavior. . . . A feeling may not be an elusive mental quality attached to an object, but rather the direct perception of a specific landscape: that of the body. The critical networks on which feelings rely include not only the traditionally acknowledged collection of brain structures known as the limbic system but also some of the brain's prefrontal cortices, and, most importantly, the brain sectors that map and integrate signals from the body."

For Damasio, feelings and the emotions from which they develop are cognitive guides within the indissociable mind/body integrated by means of mutually interactive biochemical and neural regulatory circuits that include endocrine, immune, and autonomic neural components and are comprehensible only in the context of an organism's interacting in an environment.

Daniel Dennett points out that Damasio's conceptions echo those of Aristotle and Nietzsche, and most recently those of Nicholas Humphrey, and are "retrospectively obvious." But for Descartes, rational thought occurred apart from affairs of the body. For Damasio, all imagery is determined through interaction with body proper and, ultimately, with its regulatory needs. Reasoning is "never a matter of rule-governed manipulation of 'pure' propositions (the logic-class model of reasoning), but rather is always imagistic -- even in those rare cases of sophisticated deduction in which the images are of logical formulae being manipulated." For Damasio, the environment is represented by the "modifications it causes in the body proper."

That the missing element that produces dysfunction in frontal lobe patients is an emotional linkage to imagery is demonstrated in experiments in which they emit appropriate galvanic skin responses when confronted with the stimuli that elicit the primary emotions of immediate fear or startle, but fail to do so when the stimuli are symbolic, e.g., photographs, and this despite the fact that they are able to indicate and accurately describe the emotional reactions appropriate to them. That which is missing is neither the machinery for producing emotion nor cognitive awareness of what emotions would normally be aroused by the stimulus. In an experimental test of the theory that a failure in the emotional response produces personality changes, frontal lobe patients were matched with uninjured persons and with patients with other brain injuries. As participants in a "gambling game," they were required to choose between an initially rewarded, but highly risky, option and a safe option. Only the frontal lobe patients persisted in making the wrong choice. It was especially interesting that some control subjects who occasionally chose the riskier alternative emitted a galvanic skin response before doing so. This implies that the somatic marker is learned unconsciously -- outside awareness -- a finding that is consistent with the fact that intuitions are sometimes accurate. We often know what we want to do without knowing quite or at all how we came to want to do it.

In this truly ground-breaking book, Damasio leads the way to important new conceptions of mind. But as compelling as his theoretical conjectures are, he insists that they be seen only as "provisional approximations, to be enjoyed for a while and discarded as soon as better accounts become available."