Elevated expression of brain-derived neurotrophic factor facilitates visual imprinting in chicks

Area of Science:

• Neuroscience
• Developmental Biology
• Animal Behavior

Background:

• Visual imprinting in birds is a crucial early learning process.
• The telencephalic circuit, particularly the hyperpallium densocellulare (HDCo), regulates imprinting.
• The role of neurotrophic factors in imprinting remains to be fully elucidated.

Purpose of the Study:

• To investigate the role of brain-derived neurotrophic factor (BDNF) in the neural mechanisms of visual imprinting in birds.
• To determine the critical period and signaling pathways involved in BDNF-mediated imprinting.

Main Methods:

• Quantification of BDNF mRNA-positive cells in the HDCo during the critical period.
• Analysis of tyrosine phosphorylation of TrkB after imprinting training.
• Experimental manipulation of BDNF levels in the HDCo via infusion and Trk inhibition (K252a).

Main Results:

• BDNF mRNA expression in the HDCo increased at the onset of the critical period (P0) and after imprinting training (P1).
• BDNF infusion into the HDCo at P1 induced imprinting, even with weak training.
• Trk inhibition blocked imprinting, and BDNF administration after the critical period (P7) was ineffective.

Conclusions:

• BDNF plays a critical role in promoting the induction of visual imprinting in birds.
• BDNF acts through TrkB signaling specifically during the critical period of imprinting.
• These findings elucidate the neurobiological basis of early learning and critical periods in development.