Epigenetics

Neuronal activity-induced Gadd45b promotes epigenetic DNA demethylation and adult neurogenesis Ma, D. K. et al. Science 1 Jan 2009 (doi:10.1126/science.1166859)

The regulation of neurogenesis in the adult hippocampus is poorly understood. Song and colleagues have identified Gadd45b as an immediate early gene in mature hippocampal neurons, the expression of which is induced by neuronal activity and is required for the demethylation of genes that are crucial for neurogenesis. The impaired activity-induced neurogenesis in Gadd45b-knockout mice confirms the involvement of epigenetic mechanisms in the modulation of adult neurogenesis.

Learning

Sleep and sensorimotor integration during early vocal learning in a songbird Shank, S. S. & Margoliash, D. Nature 14 Dec 2008 (doi:10.1038/nature07615)

The authors sought to determine the role of sleep in zebra finch song learning, a well-established paradigm for studying skill learning. They examined the properties of arcopallium neurons, which are known to carry information about daytime singing, during sleep before and after exposure to a 'tutor song'. Profound tutor song-specific changes in bursting activity were found the night after exposure and preceded changes in singing the next day. These findings suggest that the replay of sensory experience during sleep can modulate premotor networks as part of vocal learning.

Neurogenesis

Neurogenesis and widespread forebrain migration of distinct GABAergic neurons from the postnatal subventricular zone Inta, D. et al. Proc. Natl Acad. Sci. USA 105, 20994–20999 (2008)

The postnatal brain can generate GABAergic interneurons in the subventricular zone (SVZ) that migrate along the rostral migratory stream to populate the olfactory bulb. This study identifies robust migration of 5-HT3-positive GABAergic interneurons born in the postnatal SVZ along different pathways to cortical and subcortical brain regions during the first three postnatal weeks. Future studies in which the generation or migration of these cells is inhibited should shed light on their function.

Neurological disorders

15q13.3 microdeletions increase risk of idiopathic generalized epilepsy Helbig, I. et al. Nature Genet. 11 Jan 2009 (doi:10.1038/ng.292)

Idiopathic generalized epilepsies (IGEs) are seizure disorders, for which the underlying genetic factors remain unknown. Previous reports have pinpointed microdeletions in a 1.5-Mb region on chromosome 15 that are associated with risk of neuropsychiatric disorders. In this paper the authors sought to test whether these deletions also increase the risk for IGE and screened 1,200 unrelated patients with IGE symptoms and 3,300 controls. Approximately 1% of the IGE cases carried microdeletions at this locus, suggesting that microdeletions on chromosome 15 are the most prevalent risk factor for IGE known to date.