Delta-9-THC and nonverbal communication in monkeys

Area of Science:

• Neuroscience
• Behavioral Science
• Pharmacology

Background:

• Nonverbal communication is crucial for social interactions.
• Facial expressions play a significant role in conveying social cues.
• Understanding the effects of psychoactive substances on social communication is important.

Purpose of the Study:

• To investigate the effects of delta-9-tetrahydrocannabinol (THC) on nonverbal social communication in rhesus monkeys.
• To determine if THC affects the expressiveness of a 'stimulus' monkey or the sensitivity of a 'responder' monkey to social cues.
• To examine the impact of THC on physiological responses, such as heart rate, during social interaction.

Main Methods:

• Rhesus monkeys were trained in a cooperative conditioning paradigm to assess nonverbal communication via facial expressions.
• A 'stimulus' monkey received conditioned stimuli, and a 'responder' monkey processed its facial cues.
• Oral administration of delta-9-tetrahydrocannabinol (THC) was given to stimulus animals, responder animals, both, or neither in various combinations.

Main Results:

• THC (1.0 mg/kg) impaired the display of facial expressions in 'stimulus' monkeys.
• THC enhanced the ability of 'responder' monkeys to discriminate their partners' facial expressions.
• THC administration lowered the cardiac rates of 'responder' monkeys during the cooperative conditioning task.

Conclusions:

• Delta-9-tetrahydrocannabinol (THC) has differential effects on social communication, impairing expressiveness while enhancing sensitivity to cues.
• THC may modulate social information processing and physiological arousal in primates.
• These findings contribute to understanding the complex role of cannabinoids in social behavior and cognition.