Researchers from the Institute of Neurosciences, Spain, have identified the reason why people with Down syndrome have spatial memory or orientation problems.
They said it is a particular gene called GRIK1 is responsible for causing spatial memory problems in people with Down syndrome. The gene causes an imbalance between excitation and inhibition of neurotransmitters in the central nervous system.
The Institute of Neurosciences is a joint UMH and CSIC research center, which is devoted to the research of the physiological and pathological conditions of the nervous system.
The researchers explained that the GRIK1 gene is situated on chromosome 21, which is reproduced threefold in people who have Down syndrome, which is why they have a higher amount of those genes.
The gene plays a pivotal role in connecting the neurons and regulating the secretion of a neurotransmitter called gamma-aminobutyric acid (GABA) in the brain.
It is important for the neurons to communicate properly in order to maintain good brain function, which is possible through proper release or secretion of neurotransmitters.
The release or secretion brain chemicals usually takes place at a point of contact called synapses, which is between neurons. The proper secretion or release of neurotransmitters helps the neural circuits to function optimally.
Improper secretion or release of neurotransmitters could breakdown the balance, causing neurological issues such as memory impairment, anxiety, depression, among others.
Prof. Juan Lerma from the Institute of Neurosciences said, “We have seen in mouse models of Down syndrome that there is a problem of imbalance between excitation and inhibition of certain neuronal circuits of the hippocampus, a brain structure related to memory and orientation in space.”
“This imbalance depends on the dose of GRIK1. Through genetic manipulation techniques, we have normalized the dose of GRIK1 in our Down syndrome model, reverting this imbalance between excitation and inhibition,” added Prof. Lerma.
First study author Sergio Valbuena said, “When the dose of this gene is normalized in this transgenic mouse, spatial memory problems disappear.”
Also called Trisomy 21, Down syndrome is one of the genetic disorders caused by the existence of extra genetic material of chromosome 21. It is characterized by distinct facial appearance, along with intellectual disability and developmental delay. Down syndrome is named after John Langdon Down who described the condition for the first time in 1866.
