Imaging of striatal injury in a songbird brain

Neurological insults affect both, brain structure and behavior. The injury-induced brain plasticity and associated changes in behavior are difficult to study using classical histological methods. The magnetic resonance imaging (MRI), however, enables repeated inspection of the brain in the same individual. Here we took advantage of the songbird model with discrete brain circuitry controlling song learning and production and assessed if a conventional MRI is suitable to detect even relatively small brain changes. Our aim was to monitor injury and the following regeneration in the striatal vocal nucleus Area X that controls vocal learning in juveniles and affects song in adult songbird zebra finch (Taeniopygia guttata). The regeneration process was detected using T2-weighted images and validated by immunohistochemical (IHC) staining up to 6 months after the injury. Despite the small volume of the zebra finch brain, a satisfactory signal-to-noise ratio was achieved with reasonably short measurement times. No significant difference was found between the measurements of the lesion size obtained by MRI and IHC staining. Our data show that the non-invasive MRI technique can reliably measure and quantify the regeneration process even in a relatively small part of the brain and that the avian striatum progressively regenerates after its neurotoxic injury.