This animal model is achieved by making changes to chromosome 16 in mice, which affects 150 genes. These genetically modified mice have similar symptoms to those seen in persons with Down Syndrome:

• Smaller in size
• Craniofacial abnormalities
• Impairments in hippocampal-dependent long-term memory tasks
• Decreased number of neurons
• Decreased complexity in dendritic branching

There are also similar neuroanatomical differences to those seen in humans, like:

• Decreased excitatory input
• Altered placement of GABAergic inhibitory synapses, which innervate the base of the dendritic spine and therefore have a much larger effect on the hippocampus
• Increased long-term depression (LTD)