The neural underpinnings of aphantasia: a case study of identical twins.

Aphantasia is a condition characterized by reduced voluntary mental imagery. As this lack of mental imagery disrupts visual memory, understanding the nature of this condition can provide important insight into memory, perception, and imagery. Here, we leveraged the power of case studies to better characterize this condition by running a pair of identical twins, one with aphantasia and one without, through mental imagery tasks in a functional magnetic resonance imaging scanner. We identified objective, neural measures of aphantasia, finding less visual information in their memories, which may be due to lower connectivity between frontoparietal and occipitotemporal lobes of the brain. However, despite this difference, we surprisingly found more visual information in the aphantasic twin's memory than anticipated, suggesting that aphantasia is a spectrum rather than a discrete condition.