The Executive Brain: Frontal Lobes and the Civilized Mind

The frontal lobes, once a terra incognita, began to seem a promised land for me when I attended a landmark symposium about them at Brown University in 1992 chaired by Salloway, Malloy, and Duffy, who edited an authoritative multiauthor text based on that symposium (1). Not the least of the frontal contributions to behavior I gleaned from that symposium was everything related to compliance with treatments. Frontal lobe buffs will now welcome Elkhonen Goldberg’s new book, which continues and advances frontal exploration in the science of mind.

Goldberg is a natural storyteller, so it is fitting that this readable monograph on the frontal lobe has a preface by Oliver Sacks, who places the book with works by Edelman and Damasio in addressing “how nature and culture interact, and how brain and mind produce each other” (p. xiv). Sacks points out that

Dr. Goldberg, with whom I have viewed anatomy and discussed neural networks, opens with a personal tale of intrigue. While a student of Alexandr Luria, the premier figure of neuropsychology, Goldberg had completed his doctoral thesis work but sabotaged his thesis defense because he wanted to emigrate from the Soviet Union. Had he defended successfully he would have been deemed essential and not allowed to emigrate, and emigrating as a successful student would have discredited his beloved mentor. Playing this intricate and contradictory game, he later explains, is the most intricate example of the chess game he has had to play in his life, employing the crucial frontal lobe insight into other minds (theory of mind) that is necessary in executive processes.

Both language and executive functions emerged late in evolution. The prefrontal cortex is 29% of the human brain, 7% of the dog’s, and 3.5% of the cat’s. Don’t expect much empathy from your household Felidae.

One story is that understanding the prefrontal cortex as the command post of the brain emerged late in the history of neuropsychiatry. Unique among brain structures, it contains a map of the whole cortex. Another story is the ways in which the hemispheres differ, beginning with the Yakovlevian torque of their clockwise rotatory overlap. Goldberg explains that they differ saliently in regard to handling novelty (right) versus routine (left), much as Grossberg has found in artificially constructed neural nets (p. 45) and Gold has shown by hemispheric positron emission tomography scanning of learning tasks (p. 71).

Another story is the front-to-back organization of the frontal lobes, which know coarsely (like the boss who says don’t bother me with the details), and the posterior areas of the brain, which are repositories of specific expert knowledge, awaiting activation of their engrams by the frontal lobes for use. The frontal lobes are therefore also a bottleneck. Early dementia especially affects working knowledge, and “inane” (p. 76) actions result. It is adaptive versus veridical decision making, and Goldberg’s own cognitive bias task teases this out, unlike the perceptual matching tests typical of traditional neuropsychology and of our entire educational system, which Goldberg sees as overemphasizing veridical decision making. Almost as if they had heeded Goldberg, the Japanese, given excessively to this educational overemphasis, are in the process of trying to implement more adaptive decision making, and the Columbia Psychoanalytic Center has begun courses in critical thinking for future psychoanalysts. As a corollary, it seems there is a politically risky finding of gender differences in the cognitive bias task: males are (surprise! although Goldberg has no reaction) more dependent than females, who are more inflexible, and lesions affect the sexes differently on this dimension. The cognitive bias task also shows more novelty seeking in the left hemisphere (Goldberg is left-handedly “innovative” [p. 102], albeit converted by an “atavistic” Eastern European educational system), although previous attempts to find cognitive correlates of handedness have failed.

Goldberg is also critical of the idea of general intelligence (G factor), but he thinks an S factor (S for smart) does exist and can be seen by freewheeling lay judges, much as physical beauty can be agreed upon. The S factor, or true smarts, is executive talent, and it is the forte of the frontal lobes, as the book’s title suggests. It comes down to the theory of mind, and here Goldberg mentions kindly another master scientific storyteller, Julian Jaynes (2), who posited the bicameral mind’s emergence in 2000 BC, before which we lived in a time of spirits as unrecognized self-projections.

Goldberg elaborately describes the dorsolateral frontal damage syndrome that leaves patients like Newtonian objects: prisoners of inertia, they cannot initiate or terminate. This is typical of his memorable metaphors. He states that the tangentiality and loose associations of schizophrenia are “more than a coincidence. Schizophrenia today is regarded as a form of frontal lobe disease” (p. 129). Yes, well, in part, but the emotional midline structures and thalamus contribute. The anterior cingulate, a medial frontal structure, provides the kind of instantaneous good or bad decisions that patients with schizophrenia desperately lack in their inability to establish hierarchy (3). Dorsolateral damage leads to a loss of mental flexibility, and more right hemisphere damage involves lack of insight or general anosognosia, because only language-mediated cognition is available for introspection, a language-based process.

The orbitofrontal (stigmatized as “pseudosociopathic”) syndrome of euphoria and loss of control of impulses shows that the capacity for volitional behavior and observation of moral codes is in the frontal lobes. Examining Alexander the Great, who was 20 when he invaded Persia, Goldberg notes that frontal lobe maturity occurs at 18 and wonders if the environment can pressure people to assume adult roles early. Goldberg’s contribution of the reticulofrontal disconnection, based on the Geschwind concept of disconnection syndromes, shows how brainstem damage can cause frontal lobe dysfunction. This diagnosis was established in a successful executive who developed a ventral tegmental area lesion from a fall from a horse. Goldberg’s argument that “whereas moral and criminal codes are extracranial, moral and criminal cognition and behaviors are not” (p. 150) has forensic legs. In contrast with these “fateful disconnections” (p. 157), schizophrenia is conceptualized as “a connection that was never made” (p. 163), reversing the expected hyperfrontality of normal subjects to a hypofrontality attributable to a mesolimbic-mesocortical maldevelopment.

Higher-order cognitive impairments may be a “public blind-spot” (p. 155), traumatic brain injury a “silent epidemic” (p. 167), but attention deficit hyperactivity disorder, characterized by “a fragile connection” (p. 168), is “the disease of the decade” (p. 168). Goldberg offers a flashlight metaphor for the frontal lobes and suggests that hyperactivity may be more orbitofrontal than dorsolateral. Goldberg is critical of the American idea that everything can be fixed by a pill and describes an Australian friend who “conquered” ADHD in a support group.

Goldberg breaks down the frontal lobe syndromes into the dorsolateral syndrome of affectless pseudodepression and the orbitofrontal syndrome of impulsiveness and unconcern. The frontal poles, most appropriately, are still mysteriously elusive, even as we gain understanding of frontal and prefrontal functions. Frontal lobe patients are unable to initiate and then unable to stop (perseverative). We meet Vladimir, who endlessly elaborates a short narrative he is asked to repeat. Goldberg explains the failed Stroop Test and other afrontal behavior by contrasting a dog’s out-of-sight, out-of-mind behavior with the gibbon’s success at turning back to an object of curiosity after distraction, like the healthy human frontal ability to stay on track. In schizophrenia this abilitiy is lacking, Goldberg avers, because there are problams with the frontal lobe. Not exclusively; there are also problems with attachment of affects and valuations to cognitions, probably involving thalamic function and the hippocampus (4). Goldstein has a firm grip on the trunk of the elephant.

Following Sacks (5), Goldberg breaks down cases of Tourette’s syndrome into “stereotypic” and “phantasmagoric” subtypes, the latter requiring exploration of every incidental object. Valuable subjective descriptions from affected individuals describe a “tactile curiosity” (p. 185) and wanting to “wear the environment like clothes” (p. 188). A brief section mentions possible frontal lobe cognotropic drugs, but Goldberg believes in “jogging the brain” (p. 197) by mental exercise and, despite problems in generalizing cognitive retraining, says he is developing a program in “cognitive fitness” for everyone.

Evolution of the brain is considered throughout, but Goldberg’s solution to why the problem of the heavily interconnected cortical net of simple interactive elements is necessary for greater computational freedom borrows from neural network theory, which he discovered in a Moscow library when he was 19. The frontal lobes were needed, Goldberg argues, to provide constraint at any given time on the free process. Similarly, Davidson (6), reviewing recent studies, has suggested that the prefrontal cortex, in reciprocal connection with the amygdala, modulates the time course of emotional responding.

In the biggest conceptual leap of the book, Goldberg proposes that

Instead of applying metaphors (hydraulic, computational) to the brain, Goldberg suggests that a brain science now coming of age “may be ready to offer its own heuristic metaphors to shed light on other complex systems, including society” (p. 228). Now that is biopsychosocial!

Although the book tackles sophisticated and speculative topics, it is so accessibly written it would interest students, lawyers, and readers of the current Scientific American.