Discordance between two brain regions could lead to attention deficit disorders, including schizophrenia, bipolar disorder and major depression, a study has found. People with attention deficits have difficulty focusing and often display compulsive behaviour. Researchers from Case Western Reserve University in the US suggest these symptoms could be due to dysfunction in a gene ErbB4 that helps different brain regions communicate.
The gene is a known risk factor for psychiatric disorders, and is required to maintain healthy neurotransmitter levels in the brain. In a study published in the journal Neuron, researchers showed mice lacking ErbB4 activity in specific brain regions performed poorly on timed attention tasks. The mice struggled to pay attention and remember visual cues associated with food. Neuroscientists describe the kind of thought-driven attention required for the tasks as “top-down attention.”
Top-down attention is goal-oriented, and related to focus. People who lack efficient top-down attention are at a higher risk for attention deficit hyperactivity disorder (ADHD). The study is the first to connect ErbB4 to top-down attention. “The results reveal a mechanism for top-down attention, which could go wrong in attention disorders,” said Lin Mei, professor at Case Western Reserve University. “And since ErbB4 is a risk factor for schizophrenia, bipolar disorder, and major depression, the results provide insights into mechanisms of these disorders,” said Mei.
When the researchers attached probes to the mice to measure brain activity, they found mice without ErbB4 had brain regions that were acting independently, rather than together in synchrony. In particular, the researchers studied the prefrontal cortex – normally associated with decision-making – and the hippocampus – a region that supports memory. These two regions coordinate for a variety of brain tasks, including memory and attention.