When people watch a film or listen to a recording, strange things happen to their physiology. Scientists have noted that such social activities –or even having a conversation with another person – can induce synchronization between participants’ brain activity and heart rate. Now, a new study suggests that we can experience synchronization together, even when we observe something alone.

The locus coeruleus (LC) is a minuscule region of the brain that plays an outsized role in how our central nervous system functions. A new study suggests changes in the LC might provide a novel way of indicating the early spread of Alzheimer’s disease through the brain.