This year marks the fortieth anniversary of the publication of Philip Roth's novel Portnoy's Complaint. In 1969, the book also became fodder for one of the oddest ideas in neuroscience: the grandmother cell. What if a neuron in your head only responded to the sight of your grandmother? For a long time, many neuroscientists have dismissed it out of hand. And yet the idea will not quite die. Earlier this year a psychologist published an intriguing review of the grandmother cell, arguing that we should not be so hasty to run its obituary. Other scientists I've spoken to don't think grandmother cells actually exist, but their own ideas about how we recognize individuals are equally fascinating. I've put together what I've learned about Philip Roth's unexpected contribution to neuroscience in my latest Brain column for Discover. You can read it here.