Eliezer J. Sternberg is a neurologist at Massachusetts General Hospital and the author of “NeuroLogic: The Brain’s Hidden Rationale Behind Our Irrational Behavior.”

Nobel Prize-winning neurologist Eric R. Kandel aims to translate scientific advances in neurological and psychiatric disease into insights about why we think and act as we do. (Photo by: BSIP/UIG via Getty Images)

I called it “fascinating,” and to this day I regret the word. I was a young medical student assigned to present the case of a woman in her 60s with sudden onset of psychotic behavior. The tests showed a variety of abnormalities: an MRI of her brain with abnormal signal in the deep temporal lobe and inflammatory cells in a sample of spinal fluid. But the lynchpin in the diagnosis was surprising: a mass in the left lung. She had a lung tumor that secreted an antibody that attacked her brain, causing psychosis. Fascinating. Or so I thought until I met her, along with her husband and children, and saw a glimpse of how a family confronts a devastating diagnosis, realizing that the real story of medicine lies beyond the research and revelations, beyond the scans and the science, in the human experience.

(Farrar, Straus and Giroux)

Moving from the hospital to the laboratory, neuroscientists are similarly challenged to bridge the gap: Synaptic transmission and enzymatic cascades aren’t easily translated into insights about why we think or act the way we do. But Eric R. Kandel, winner of the Nobel Prize for his memory research, is uniquely qualified. By studying how the neurons of the sea slug Aplysia californica generate a gill-withdrawal response, he mapped out the biochemical pathway that turns environmental stimuli into learned behavior — a finding that directly linked biological mouthfuls like “cyclic adenosine monophosphate response element binding protein” to more relatable and profound concepts: how we learn and remember.

In his new book, “The Disordered Mind: What Unusual Brains Tell Us About Ourselves,” Kandel says that “advances in the biology of mind offer the possibility of a new humanism, one that merges the sciences, which are concerned with the natural world, and the humanities, which are concerned with the meaning of human experience.” With that goal in mind, Kandel expertly surveys the great scientific advances in neurological and psychiatric disease, from the role of neurotransmitters in depression and bipolar disorder, to the neuronal anomalies in schizophrenia, to the genetics underlying Alzheimer’s and Parkinson’s. The book is encyclopedic in covering not only the molecular biology, diagnostic techniques and treatment of each disease, but also in tracing the relevant scientific advances through history.

Yet what’s notably missing amid all that information, much of which can be found in neurology or psychiatry textbooks, is the tangible human connection or, as the title promises, what all these “unusual brains tell us about ourselves.” For instance, the chapter on depression opens not with broad questions about the nature of emotion but rather with the simple assertion that “we all experience emotional states.” The pages that follow describe the symptoms of depression, detail how Hippocrates first recognized the condition some 25 centuries ago, account for the brain regions involved, and discuss various treatments like medication and psychotherapy, but there’s faintly a mention of the repercussions for our understanding of emotion.

Even in a section titled “Emotion in Decision-Making,” Kandel misses an opportunity to make the connection. He talks about a famous case: a patient named Elliot who sustained damage to his frontal lobe and developed problems with both decision-making and emotional expression, suddenly having no reaction to emotionally charged stimuli such as a picture of a severed foot. The case raises provocative questions. Why did this pattern of brain damage cause simultaneous deficits in emotion and decision-making? What does this mean about the relationship between them? Does this case illuminate why emotion is so integrated in our decision-making, often overriding our better judgement? Kandel does not ask or address these questions, which is unfortunate because there is a rich literature on this very case that could have brought Kandel’s work to life.

In his book “Descartes’ Error: Emotion, Reason, and the Human Brain,” neuroscientist Antonio Damasio postulates that the area damaged in Elliot’s brain creates something called “somatic markers,” physical representations of emotional states that are stored in memory and affect future decisions. So, for example, suppose you are visiting universities that you’d like to attend and, during a tour of one of them, the tour guide screams at you for walking on the grass, making you cry. That emotion is stored, Damasio says, as a somatic marker and becomes permanently associated with your memories of that university. Months from now, as you make your decision about which school to attend, that emotion reemerges to influence your choice. You may not know why, but a feeling in your gut tells you that’s not the school for you. This is Damasio’s theory of how emotion and decision-making are intertwined: Our intuition or “gut feelings” are derived from emotions we’ve experienced and accumulated through life, and they are crucial in guiding how we choose to act.

Had Kandel spent more time merging the sciences with the humanities, a bar he set for his book, he could have transcended the raw research to address deeper questions. Like the section on emotion, the other disorders in the book receive equally pedantic treatments. When discussing memory and its pathological counterpart, dementia, Kandel delves into amyloid plaque pathology in Alzheimer’s, abnormal proteins in the pathophysiology of Alzheimer’s, and the dementia genetics research on presenilin 1 and C90RF72, but offers no examples to illustrate how any of this affects the way a layperson might think about the nature of memory in everyday life. In a chapter on autism and social behavior, Kandel presents a master class on the history of the field, encapsulating in clear paragraphs the contributions of Leo Kanner, Hans Asberger and Bruno Bettelheim, yet he doesn’t pause to contemplate the ramifications for the nature of social interaction.

The treatment of the subject matter, while coherent and systematic, seems emotionally distant from the human-level questions it concerns. Kandel unintentionally mirrors the tone of his work by quoting the psychologist Uta Frith as she describes her early interest in children with autism: “I wanted to find out what makes them behave so strangely with other people, and what made them so totally untouched by the kind of everyday communication we take for granted. . . . They were completely fascinating.” Scientific research can be so engrossing that even the greatest scholars can occasionally lose sight of the fact that behind all of that useful and fascinating data, there are human beings.

As an introduction to the biological underpinnings of neurological and psychiatric disease, “The Disordered Mind” is a lucidly written, accessible and fascinating read. Kandel approaches each topic with the same rigor and discipline that he must have exhibited when studying the basis of the gill-withdrawal response in primitive sea slugs. It is that meticulousness that has made him the greatest neuroscientist of our time. But if the goal is to bridge the sciences and the humanities, perhaps the scientific method in isolation falls short. To really understand the intimate connection between the mind and the myriad facets of human consciousness to which it gives rise, we must not only investigate the coding of the genome, the mapping of nerves and the architecture of the brain, but also the experience of the heart.

The Disordered Mind
What Unusual Brains Tell Us About Ourselves

By Eric R. Kandel

Farrar, Straus and Giroux. 285 pp. $30