The Tell-Tale Brain: the quest for what makes us human

In his incredibly insightful, entertaining, and thought-provoking new book, The Tell-Tale Brain: A Neuroscientist’s Quest For What Makes Us Human, Ramachandran begins by challenging readers to consider Disreali’s rhetorical question, “Is man an ape or angel?”

Although Victorian scientists including Huxley and Owen argued for decades over this misleading question, and although modern scientists, according to Ramachandran, sometimes describe humans as ‘mere apes’, Ramachandran draws upon evolutionary, brain, and behavioral science to elucidate both the neurological and behavioral continuity that exists across apes and humans, and the quintessentially human attributes that are unique to humans.

Notably, quintessentially human attributes are revealed through a scientific understanding of the problems and possibilities unique to humans. As noted by Ramachandran, many of the neurological disorders and neuropsychiatric problems that are unique to humans arise as a result of some level of dysfunction or disequilibrium in recently evolved brain structures and functions. For example, Ramachandran argues that is it hard to imagine an ape suffering from Cotard syndrome, a rare disorder in which people hold the delusional belief that they are dead; or Capgras syndrome, another rare disorder in which people hold the delusional belief that those around them have been replaced by imposters. These disorders are unique to humans and can be regarded as disturbances of consciousness and self-awareness. At the same time, self-awareness and language, two quintessentially human attributes, help to explain why humor is exclusively human but laughter is not. Furthermore, although Orangutans can imitate simple skills such as opening a lock, the imitation of more demanding skills such as spearing an antelope is seen only in humans. Similarly, Disreali’s metaphorical angel, which implies high level moral thinking, feeling, and action, can only arise in a brain that evolved the capacity to envision actions and consequences and choose among them.

Ramachandran proposes that, in our recent evolution, perhaps not more than 150,000 years ago, human brains changed in important ways, allowing us to learn to perform new tasks. For example, one possible reason why Orangutans and humans differ in their ability to imitate the actions of others is that humans have a more complex mirror neuron system than their primate cousins. Mirror neurons are activated both when we perform an action or when we observe someone else performing the same action, and these neurons appear to help animals and humans imitate the behaviors they observe. Notably, Ramachandran argues that humans have a more complex and sophisticated mirror neuron system that evolved to facilitate increased awareness of others but which was also instrumental in bringing about self-awareness in humans. Ramachandran suggests that Cotard syndrome may result from damage to mirror neuron circuits, causing a person to lose self-awareness. Similarly, ideational apraxia, a neurological syndrome in which damage to the left supremarginal gyrus leads to difficulty in both performing and miming skilled actions and recognizing the same action performed by someone else, may be a dysfunction of the mirror neuron system, as mirror neurons have been show to exist in the left supremarginal gyrus. Although some have argued that invoking mirror neurons as a mechanism to explain complex human behaviors such as imitation is both overly simplistic and reductionist, Ramachandran counters that similarly simplistic and reductionist approaches to scientific explanation have proved useful in the past (e.g., the discovery by John Pettigrew and colleagues of disparity-detecting neurons in the visual cortex which help to explain stereoscopic vision). Ramachandran goes on to argue that mirror neuron deficits may be critical for understanding the problems associated with autism.

Ramachandran draws out some very interesting connections between synesthesia, which involves cross-modal interactions between sensory faculties, such as smell, hearing, and touch, and creativity, which often involves cross-modal associations that aid in problem solving activity. He describes how space-mapping areas of the parietal lobe might have been co-opted during evolution to facilitate the development of numeracy and systems of number representation. Similarly, he argues that the inferior parietal lobe, which originally evolved for cross-modal abstraction, evolved further in humans and was critical to the emergence of language functions.

Ramachandran also provides a fascinating evolutionary and neuroscientific account of aesthetics, elaborating in particular his nine laws of aesthetics. Specifically, Ramachandran considers the importance the principles of grouping, peak shift, contrast, isolation, perceptual problem solving, abhorrence of coincidences, orderliness, symmetry, and metaphor in driving aesthetic responses to art. For example, Ramachandran argues that perceptual grouping evolved to facilitate the recognition of objects that are partially occluded or fragmented under camouflage. When previously fragmented features are grouped perceptually, this corresponds to a shift from a more disorderly brain state to a more orderly state, where spike trains become synchronized. This synchrony tells higher brain areas that fragmented parts are part of one object, and this synchronous brain state may also help to explain the aesthetic to grouping and the appeal of grouping as a strategy that artists and advertisers use to make their work more appealing to viewers. The peak shift principle of aesthetics resonates with findings from animal research which demonstrate that when you teach an animal to discriminate between two stimuli (e.g., reward them for selecting a standard rectangle over a square), the animal will come to prefer or select a longer, skinnier triangle over the standard rectangle if presented with the choice. In a similar fashion, a caricature of Nixon, which exaggerates the features of Nixon’s face that deviate from the average face is more striking and more appealing and invokes more of an emotional response from viewers than would a simple photograph of Nixon’s face. Artists have long understood this principle of peak shift and Ramachandran points to the dancing nymph of Rajasthan as an example of a piece of art that conveys an incredibly beautiful sense of movement, even though she is anatomically impossible in terms of her chest to waist and hip to waist ratios.

Ramachandran also tackles the somewhat intangible construct of the self and describes seven key features of experience that uphold our sense of self – features of experience that science needs to explain. Included in Ramachandran’s list are: Unity — although we are a collection of multiple sensory experiences and multiple goals, memories, emotions, beliefs, and action, we nevertheless generally feel like one person; Continuity – despite the vast number of distinct events punctuating our life, we feel a sense of continuity and identity through time; Embodiment – although flexible and fragile at times, our sense of self generally involves a feeling of being anchored and at home in our body; Privacy – we each have a private mental life, and although we can empathize with others, we cannot literally feel what they feel, and this privacy is core to our sense of self; Social embedding – notwithstanding its privacy, the self is relational and part of a social environment; Free will – we have a sense of being able to consciously choose between alternative courses of action; Self-awareness – the self is aware of itself. Ramachandran accepts that we do not yet know how free will comes about, but he suggests that at least two brain regions are crucially involved: the supramarginal gyrus on the left side of the brain, which is involved in the ability to conjure up and envisage different potential courses of action; and the anterior cingulate, which is involved in the motivation to select one action over another.

For anyone looking to catalyze their creative sensibilities over the summer months, I highly recommend this book as a good sunshine holiday read. Although my wife sometimes chides me for reading ‘academic’ books on the beach, I can think of nothing better to do before rediscovering myself while swimming in the ocean.

Originally posted May 31, 2012 in ‘In One Lifespan’ @PsychologyToday.com

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References

Ramachandran, V.S. (2011). The Tell-Tale Brain: A Neuroscientist’s Quest For What Makes Us Human. New York, Norton & Company

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