THE TELL-TALE BRAIN

Ramachandran (Psychology and Neurosciences/Univ. of California, San Diego; A Brief Tour of Human Consciousness, 2005, etc.) sets his sights on explaining the neuroscience that underlies characteristics he considers unique to humans beings.

The author suggests that some 150,000 years ago, hominid brains underwent a “phase transition” (like water becoming ice), so that some brain centers expanded and developed new functions, leading to language, aesthetics, consciousness and self-awareness. Like Oliver Sacks, Ramachandran finds illumination in the analysis of patients with anomalous syndromes. Thus he begins with studies of phantom limbs and synesthesia, most commonly manifest as the condition in which individuals see specific colors associated with numbers or musical notes. The roster of syndromes grows to include language and memory disorders, cases in which a stroke patient denies the existence of a paralyzed limb, a patient recognizes his mother’s face but says she is an impostor, or a patient who believes himself dead. Ramachandran’s argues that the lesions in such patients disrupt specific sites in multi-branching pathways that create mismatches between sensory and motor areas, or between emotional and perceptual areas. In turn, the brain adapts, often making matters worse. Early on, the author introduces mirror neurons, which are abundant in human brains. These are cells that mimic the actions of another person as you watch, but are inhibited from executing the action. They are considered the source of empathy or “theory of mind” by which humans can read other’s intentions. Ramachandran invokes mirror neurons as essential for social learning, language and cultural transmission. For the most part, the author argues convincingly, except where he defines aesthetic principles, which seem no more than a rehash of old Gestalt ideas. Nor is it certain that all the traits he discusses are unique to humans.

Despite some minor flaws, Ramachandran produces an exhilarating and at times funny text that invites discussion and experimentation.