Gene That Helps Brain Regions Communicate May Be Linked to ADHD, Study Finds
Dysfunctions in ErbB4, a gene that facilitates communication between the brain’s prefrontal cortex and the hippocampus, may be responsible for attention and memory deficits.
April 10, 2018
New research1 identifies a critical gene, known as ErbB4, as a major factor influencing the attention-related symptoms of attention deficit disorder (ADHD or ADD), schizophrenia, bipolar disorder, and major depressive disorder.
The study, published last month in the journal Neuron, was conducted by a research team at Case Western Reserve University that manipulated gene levels in genetically modified mice’s brains to test the impact of the ErbB4 gene on attention and memory. Mice who lacked the ErbB4 gene (previously identified as a risk factor for psychiatric disorders) struggled on timed tests of attention, memory, and visual processing — symptoms collectively known as impaired “top-down attention.”
When functioning correctly, top-down attention is a complex process that requires several brain regions to work together. Two of the most critical are the hippocampus — which supports memory — and the prefrontal cortex, which processes complex decision-making. Mice who lacked the ErbB4 gene had activity in both of these brain regions; however, signals passed between the regions were asynchronous when compared to brains with normal ErbB4 activity. The researchers concluded that ErbB4 must help facilitate communication between the two brain regions — possibly using a neurotransmitter called GABA, which was low in the mice without ErbB4. Dysfunctions in this communication are a likely cause of the attention challenges seen in a wide variety of psychiatric disorders, they said.
“We found that top-down attention, previously thought to be controlled by the prefrontal cortex, also involves the hippocampus in a manner where the two regions are highly synchronized when attention is high,” said Lin Mei, Ph.D., the lead author of the study. “Our findings give importance to synchrony between the prefrontal cortex and hippocampus in top-down attention and open up the possibility that attention deficit disorders, like ADHD, might involve impairments in the synchrony between these two regions.”
Further research, using the same mutant mice, will dig further into how specifically ErbB4 works in the brain and how exactly it causes attention-related symptoms, Mei said.
For more on top-down signaling, and the impact of neural networks connecting regions of the ADHD brain, read “Is ADHD a Spectrum Disorder?”
1 Tan, Zhibing, et al. “Dynamic ErbB4 Activity in Hippocampal-Prefrontal Synchrony and Top-Down Attention in Rodents.” Neuron, Mar. 2018, doi:10.1016/j.neuron.2018.03.018.
