A team of neuroscience researchers at Ruhr-Universität Bochum (RUB) in Germany examined what happens in the brain when hearing gradually deteriorates over time. What they discovered was that key areas of the brain are reorganized, and this has a negative effect on memory.
The results of the study were published last month in journal Cerebral Cortex.
Hearing Loss and the Brain
The researchers studied the brain of mice that exhibit hereditary hearing loss, similar to age related hearing loss in humans. The scientists analysed the density of neurotransmitter receptors in the brain that are crucial for memory formation. They also researched the extent to which information storage in the brain’s most important memory organ, the hippocampus, was affected.
Memory is enabled by a process called synaptic plasticity. In the hippocampus, synaptic plasticity was chronically impaired by progressive hearing loss. The distribution and density of neurotransmitter receptors in sensory and memory regions of the brain also changed constantly.
The greater the degree of hearing loss, the poorer were both synaptic plasticity and memory ability.
“Our results provide new insights into the putative cause of the relationship between cognitive decline and age-related hearing loss in humans. We believe that the constant changes in neurotransmitter receptor expression caused by progressive hearing loss create shifting sands at the level of sensory information processing that prevent the hippocampus from working effectively”
–Denise Manahan-Vaughan, PhD
The study was funded by the Collaborative Research Center (SFB) 874 of the German Research Foundation. SFB 874 “Integration and Representation of Sensory Processes” has existed at RUB since 2010. The researchers investigate how sensory signals generate neuronal maps, resulting in complex behaviour and memory formation. Daniela Beckmann and Mikro Feldmann have also completed the medical students’ program of the SFB 874 and the International Graduate School of Neuroscience.
Daniela Beckmann, Mirko Feldmann, Olena Shchyglo, Denise Manahan-Vaughan: Hippocampal synaptic plasticity, spatial memory, and neurotransmitter receptor expression are profoundly altered by gradual loss of hearing ability, in: Cerebral Cortex, 2020, DOI: 10.1093/cercor/bhaa061