Figure 2
From: Learning-related brain hemispheric dominance in sleeping songbirds
Neuronal activation in HVC is lateralised during sleep.
Mean number of Zenk-immunopositive neurons per square millimetre is shown for the different brain regions. Grey bars represent the left hemisphere and white bars represent the right hemisphere. Error bars represent ± s.e.m. (a) In the hippocampus, a control brain region that is not implicated in song learning, Zenk expression levels are low and not lateralised. (b) In the NCM during sleep, there were high levels of Zenk expression but no differences between groups or hemispheres. (c) We found high activation levels in the right HVC in all conditions, while Zenk expression levels were low in the left HVC. (d) In a separate group of juvenile males in which IEG expression was measured immediately after they had been singing, there were high levels of Zenk expression in both left and right HVC. (n = 4) (e) Photomicrographs of juvenile zebra finch brains showing Zenk-immunostaining. Representative images at the level of the lateral NCM, HVC and hippocampus (HP) are shown for the silence, novel and tutor stimulus groups, in the left and right hemispheres. Arrows in the upper left image indicate examples of zenk-positive cells (black immunolabelling). Scale bar represents 0.2 mm.
