Changes in Heart Rate Variability during a tonic immobility test in quail

Area of Science:

• Animal behavior
• Autonomic nervous system physiology
• Fear response mechanisms

Background:

• Tonic immobility (TI) is an innate fear response involving significant autonomic nervous system (ANS) activity.
• Understanding the interplay between sympathetic and parasympathetic nervous systems during TI is crucial for elucidating fear responses.

Purpose of the Study:

• To investigate the distinct roles of sympathetic and parasympathetic nervous systems during TI using Heart Rate Variability (HRV).
• To compare autonomic responses in quail lines genetically selected for differing TI durations (LTI, STI) and a control line (CTI).

Main Methods:

• Surgical implantation of telemetric devices for electrocardiogram (ECG) recording in quail.
• Analysis of Heart Rate Variability (HRV) to assess sympathovagal balance before, during, and after TI tests.
• Comparison of autonomic responses across LTI, STI, and CTI quail lines.

Main Results:

• No significant differences in resting heart rate were observed between quail lines.
• TI induction, regardless of effectiveness, increased heart rate and sympathetic dominance.
• Effective TI in CTI quail showed lower parasympathetic activity compared to non-effective inductions.
• Sympathetic dominance initially increased then declined during TI, with sustained low parasympathetic activity in CTI and STI lines.
• All lines exhibited increased autonomic activity at TI's end, with enhanced parasympathetic influence in CTI and STI quail.

Conclusions:

• Autonomic reflex changes alone do not fully explain susceptibility to TI.
• Fear perception and associated behavioral differences likely play a significant role in TI duration and autonomic responses.
• HRV analysis provides insights into the complex interplay of the autonomic nervous system during fear responses in quail.