Dopamine-dependent long term depression of mediated transmission profoundly disrupts normal synaptic transmission between hippocampus and PFC. These results show how dopaminergic activation induces long-term hypofunction of NMDARs, which can contribute to disordered functional connectivity, a characteristic that is a hallmark of psychiatric disorders such as schizophrenia. Credit: https://neurowiki2012.wikispaces.com/file/view/Reward_circuit.jpg/315908202/Reward_circuit.jpg
New research reveals mechanisms that trigger disruption in the brain’s communication channels linked to symptoms in psychiatric disorders. This research could have important implications for treating symptoms of brain disorders.
Many of our everyday cognitive functions such as learning and memory rely on normal communication between the 2 regions of the brain – the hippocampus and prefrontal cortex. While previous studies have identified disruption to communication channels in these 2 areas of the brain contribute to symptoms in psychiatric disorders, the mechanisms that lead to these disturbances have been largely unknown, until now.
In this study, led by Professor Zafar Bashir from Bristol’s School of Physiology and Pharmacology, the researchers studied glutamate and dopamine, which work together in controlling normal transmission between these brain regions by communicating chemical information throughout our brain and are disrupted in schizophrenics. Subtle changes in the interplay of these transmitters completely altered the flow of information from the hippocampus to prefrontal cortex. Over-activation of the D2 class of dopamine receptors led to suppression of the function of NMDA receptors, which are activated by the neurotransmitter glutamate, at the synaptic connection between hippocampus and prefrontal cortex. This in turn leads to a marked disruption of communication between these brain regions.
Dr Paul Banks, one of the researchers, said: “Our findings demonstrate a mechanism for how dopamine neurotransmission can influence NMDA receptor function at a connection in the brain needed for complex mental tasks which are disrupted in schizophrenic patients. It has been known for some time that dopamine and NMDA receptor function are altered in schizophrenic patients – our data mirror the direction of these changes and therefore might give insight into how these changes come about mechanistically.”
http://www.bristol.ac.uk/news/2015/august/brain-channels.html
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