The Profound Abyss of Consciousness

In “The Abyss”, published in a recent issue of the New Yorker, Oliver Sacks elegantly reports on the clinical case of Clive Wearing, a professional musician who became amnesic after suffering herpes-simplex viral encephalitis. It is natural to ask whether Sacks’ anecdotal account of “the most devastating case of amnesia ever recorded” is scientifically reliable. By reviewing published scientific accounts of Wearing’s condition, and cases of a similar nature, I will evaluate Sacks interpretation of Clive’s case.  As modern science attempts to decipher all the effects of brain damage on memory —and thus explain the complete neuropsychology of memory— Sacks reminds us that there is still much to be understood. Could science have predicted the detailed effects of brain damage and the unaffected cognitive areas? How is it possible that Clive retained his incredible musical memories and is able to perform his favorite pieces of classical music with fervor and continuity? How can Clive retain strong emotional memories about his wife but nothing else?  Oliver Sacks challenges the field of cognitive neuroscience, and particularly, the investigation of memory and consciousness, by asserting that to truly understand memory one must dig deeply into the story behind the amnesia.  Clive’s case opens the possibility that today’s cognitive neuroscience would potentially be complemented by a more person-oriented approach.

As a neurologist, one of Oliver Sacks’ talents is his ability to convert a monotonic medical report —where the main goal is to arrive at a diagnosis— into a rich clinical recounting that retains its scientific validity while showing the “heroes” behind the case (Silberman, 2002). For Sacks, this revival of the background medical story is crucial in an area where each case of amnesia is physiologically unique, with its own history and challenges. A well narrated case of amnesia can reveal the abyss in our current understanding of consciousness and memory. It is the narration that lets us share with the amnesiacs their attempts to maintain the fluidity of their personality and their consciousness by pushing the limits of their human capacities. However, does Sacks’ talent in clinical case narration lead us  melodramatic accounts of brain damage that are far from the true reality of amnesia?

     Sacks depicts Clive as being deprived from accessing any memories: not only does he have severe retrograde amnesia (he is unable to remember events before the infection), but he also is incapable of retaining new memories, both semantic and episodic. However, it is clear from his writing style that Sacks is explicitly departing from a purely diagnostic view of Clive. He hints about his ‘suspicion’ of frontal lobe damage based on Clive’s jokiness and lack of social inhibitions, and briefly discusses the importance of the temporal lobe in memory. Instead of emphasizing the neurological damages suffered by Mr. Wearing, his diagnosis simply speaks of damage to “areas known to affect memory.” As an alternative, Sacks carefully constructed the narration centered on Clive’s state of consciousness: a constant agony of being “completely incapable of thinking” and feeling “deprived of consciousness and life itself” as Clive asserts and denies his existence. His mind seems to be in a state of chaos as he moves rapidly from thought to thought, a speed that is reflected in his verbose speech. And yet, his ability to perform music is untouched, and even shows flexibility as he “improvise[s], joke[s], and play[s] with any piece of music.” Clive becomes our hero, the hero who survived a traumatic amnesia that was unable to take from him what he valued the most: his love for music and his wife Deborah.

Is Sacks’ Clive the same Mr. Wearing (or simply ‘C’) known to cognitive neuroscientists? Despite different audiences and writing styles, the account is in fact mostly reliable. As described in the scientific literature, even though Clive is not the first case of amnesia in a professional musician or the first case of amnesia caused by encephalitis, his case truly stands out. Clive does have a severe case of amnesia in comparison to other patients, with the deficits being evident in both semantic and episodic memories. Furthermore, he is attributed a “delusion” possibly caused by the amnesia: he shows an unusual preoccupation about his state of consciousness (Wilson, Baddeley, & Kapur, 1995). Early CT scans of Clive’s brain immediately after the damage showed low density tissue mainly in the left temporal lobe, but extending into the inferior and posterior frontal lobe, and even into the right temporal lobe (Wilson & Wearing, 1995). The abundant statistics collected from psychological tests from Clive show that his short term memory appears to be normal (with an average score in the digit-span test), but his episodic memory is highly impaired (he score 4/43 on an episodic memory test). He also shows marked impaired recall, and shows no visual-spatial memory (Kaplan & Bain, 1999).

Even thought the scientific literature converted Sacks’ description of the “most devastating case of amnesia” into more formal words and numbers, Sacks’ description does appear to be accurate.  In comparison to Clive, consider the case of “JL”, a professional physiotherapist with bilateral damage to the frontal and temporal lobes caused by the same virus  (Geffen, Rosemary, M, & Geffen, 2007). The damage in Clive seems to encompass all the difficulties encountered by “JL” but with even deeper challenges. “JL” spares are immediate memory, perceptual priming, and cognitive problem-solving abilities. However, she applies her procedural skills with lack of flexibility, in what neuroscientists have described as “lack of coordination” among various types of memory, preventing her from performing the complex professional procedures expected from her.

Coming from a commercial magazine, Sacks’ account does have important gaps that need to be filled to satisfy the inquisitive minds of the neuroscientists. For instance, a discussion of how motor task learning can occur would be highly relevant; particularly since Clive’s musical skills remain intact and he shows motor learning abilities which would otherwise seem ‘miraculous’ from Sacks’s account. In addition, Sacks’ discussion about emotional memory is superficial and highly centered on the anecdotal account of Clive’s love. In particular, Sacks claims emotional memory is “the least understood,” without truly elaborating his argument or why this might be the case. A review of the literature strongly suggests that particular brain structures such as the amygdala, the hippocampus, and the prefrontal cortex play important role in the retrieval of emotional memories (Buchanan, 2007). Furthermore, it is well known that patients with damage to both the amygdala and the hippocampus retrieved fewer unpleasant autobiographical memories, which would suggest that the positive emotions in Clive such as love would be less likely to be lost, especially if reinforced on a regular basis. Recently, researchers have suggested a possible mechanism for how such memories are formed, involving molecular changes. In particular, it has been found that the neurotransmitter norepinephrine helps form new memories through a receptor on the surface of nerve cells (GluR1), with memories being coded based on the strength of the signals (Barry, 2007). Thus, Sacks statement needs to be more elaborate, and critically review recent findings in neuropsychology of memory.

The main weakness of Oliver Sacks’ account arises from a purely Swiss Army view of the brain that is particularly compatible with the type of narration in which he is engaging. For instance, he arguably attributes “consciousness and sensibility” as dependent on the cerebral cortex, whereas procedural memories are depicted as dependent on “subcortical structures such as the basal ganglia.” However, to understand the neuropsychology of learning and memory, a more distributed view of memories (especially memory pathways based on computational tradeoffs rather than by human made categories) should be favored (Atallah, Frank, & O'Reilly, 2004).Terms repeatedly used by Sacks such as declarative and procedural reveal only the surface of memory and fail to address the subtleties of memories. Even though “emotional memory found in structure X” is a more appealing headline, the complexity of memory is likely to be beyond those terms.

Nevertheless, the account in The New Yorker is widely accessible to a variety of audiences and shows the challenges within the “neurologist’s notebook”, challenges which remain to be completely understood: from the mysteries behind a symphony, to the endurance of love in amnesia.  First, Sacks reminds us that we must favor theories that follow Occam’s razor (they are the simples theories that explain all observations) and narrating them to those without a background in neuroscience is the best test for that assertion. Second, Sacks reminds us of details that may be relevant in understanding amnesia but overlooked behind statistics, imaging studies, or psychological tests. Just as Clive believed that the key of a successful performance was beyond the music on page (he believed he needed to know even the details of the last meal taken by the audience) (Wilson & Wearing, 1995), so the key for learning and memory lie on the particularities of each of case.  A more anecdotal approach could prove to be highly complementary in a field where each case of amnesia is completely different and where new perspectives may arise based on subjective understandings of consciousness and the experience of ever-present time in amnesia. Sacks invites us to pay attention to amnesia with a human approach, where scientific findings are based on vivid observations from deep curiosity and shared struggles faced each day by amnesiacs as they merge the abyss of consciousness.