A variability-generating circuit goes awry in a songbird model of the FOXP2 speech disorder

Abstract

FOXP2 mutations cause a monogenic speech disorder in humans. In this issue of Neuron, Murugan et al. (2013) show that knockdown of FoxP2 in the songbird basal ganglia causes abnormal vocal variability and excess bursting in a frontal cortical nucleus.

Figure 1. FoxP2 knockdown in the songbird BG blocks leads to dysregulation of vocal variability

(A) Schematic of the avian song system. Area X is a striatopallidal nucleus in the basal ganglia and LMAN is a thalamorecipient portion of the BG-thalamocortical loop. LMAN drives song variability through its projection to RA, a motor cortex-like nucleus. (B) Song variability is reduced when birds sing to a female (directed song), compared to when singing alone (undirected song). Knockdown of FoxP2 in Area X blocks this context-dependent reduction in variability. (C) In control birds, LMAN neurons exhibit randomly timed bursts during undirected song, but switch to tonic precise firing during directed song. (D) FoxP2 knockdown prevents this switch in LMAN firing. Rasters are schematic representations of findings from Murugan et al. (2013)