“Testing the Proustian Hypothesis” — that our senses of smell and taste are uniquely sentimental. This is because smell and taste are the only senses that connect directly to the hippocampus, the center of the brain’s long-term memory. Their mark is indelible. All our other senses (sight, touch, and hearing) are first processed by the thalamus, the source of language and the front door to consciousness. As a result, these senses are much less efficient at summoning up our past.