Handedness is associated with immune functioning and behavioural reactivity in rhesus macaques

Area of Science:

• Neuroscience
• Immunology
• Primate Behavior

Background:

• Behavioral lateralization, or handedness, is observed across species.
• Immune functioning and behavioral reactivity are complex traits.
• Previous research in rodents suggested links between these domains.

Purpose of the Study:

• To investigate the relationship between handedness, immune functioning, and behavioral reactivity in rhesus macaques.
• To determine if specific immune measures correlate with hand preference and behavioral responses to threat.

Main Methods:

• Assessed immune functioning using absolute counts of CD4+ (T-helper) and CD8+ (T-suppressor) cells.
• Profiled hand preference via a quadrupedal food-reaching task.
• Derived behavioral reactivity profiles from responses to an invasive threat stimulus.

Main Results:

• A positive correlation was observed between the frequency of right-hand reaches and absolute CD4+ cell counts.
• Increased right-hand reach frequency also correlated with higher levels of human-directed aggression.
• No association was found between immune measures and the strength of hand preference.

Conclusions:

• Behavioral lateralization in rhesus macaques is associated with both immune functioning (CD4+ cell counts) and behavioral reactivity (aggression).
• These findings extend previous research from rodents to nonhuman primates, supporting a broader link between lateralization, immunity, and behavior.