Dutch researchers have increased the neuronal functioning of mice with a common form of inherited mental retardation by placing them in a stimulating environment. The work, which was carried out by scientists at the University of Amsterdam, is published in the latest edition of the journal Neuron. Fragile X Syndrome is the most common form of inherited mental retardation, occurring in 1 in 3,600 males and 1 in 4-6,000 females. It is caused by a mutation on the Fmr1 (Fragile X Mental Retardation) gene, which is located on the X chromosome. In addition to low IQs and learning difficulties, patients often have behavioural disorders such as hyperactivity and attention-deficit. There is no cure, but the symptoms can be alleviated with special education, speech therapy and behavioural therapy. Medications can also be used to address issues such as anxiety or aggression. In this latest piece of research, the scientists studied mice with the syndrome, focusing in particular on the prefrontal cortex, the part of the brain responsible for learning and memory. They found that the neurons in the mice's brains had lower levels of a process called 'long-term potentiation', which is involved in learning and memory. This problem was caused by abnormalities in the channels which regulate the flow of calcium into the neurons. Stimulating the neurons enhanced calcium signalling, and restored normal long-term potentiation and neuronal plasticity. Furthermore, placing the mice in an interesting environment with toys, running wheels and different objects also had the effect of restoring normal neuronal plasticity. This ties in well with the observation that human Fragile X patients are able to learn and memorise information, but need more repetitions and stimulation to achieve this. 'Increased sensory, cognitive and motor stimulation by environmental enrichment facilitates the development of synaptic plasticity in cortical areas involved in higher cognitive function,' the researchers conclude.