Figure 3
From: Learning-related brain hemispheric dominance in sleeping songbirds
Neuronal activation in the lateral NCM is lateralised during sleep: poor learners show right-dominant activation in the NCM, while good learners have a left-dominant expression pattern.
(a) Lateralisation ratios (L − R)/(L + R) were calculated for each subject from the number of Zenk-immunopositive cells per square millimetre in the NCM. Song similarity percentages on the x-axis indicate to which degree the juveniles had imitated their fathers' songs. Black triangles represent birds that were exposed to tutor song during the day; open circles, novel song; grey squares, silence. The regression line shown is for the three stimulus groups together and the correlation is significant (Pearson's r = 0.630, p = 0.007). (b) Mean number of Zenk-immunopositive neurons per square millimetre in the NCM for all experimental groups grouped together (silence, novel, tutor), but individuals are divided into two groups based on learning proficiency. ‘Poor’: song similarity <55% ( = mid-range); ‘good’: song similarity >55%. Grey bars represent the left hemisphere and white bars represent the right hemisphere. Poor, n = 9, good, n = 8. Error bars represent ± s.e.m. (c) Spectrograms of juveniles that produced a poor or good imitation of their tutor's song. Left: Juvenile had a song similarity of 28% with its tutor. Right: Juvenile had a song similarity of 81% with its tutor.
