Macaque monkeys and humans sample temporal regularities in the acoustic environment.

Area of Science:

• Neuroscience
• Comparative Cognition
• Bioacoustics

Background:

• Rhythm processing and synchronization are crucial for complex sensorimotor behaviors in humans.
• While vocal learners exhibit advanced rhythmic abilities, primates' capacities remain less understood.
• A potential link exists between rhythm processing and sophisticated human behaviors, prompting investigation into our closest relatives.

Purpose of the Study:

• To investigate whether macaque monkeys exhibit endogenous rhythm processing capabilities similar to humans.
• To explore the neural mechanisms underlying passive auditory rhythm perception in non-human primates.
• To understand the evolutionary origins of rhythm cognition by comparing neural responses in macaques and humans.

Main Methods:

• Electroencephalography (EEG) was recorded from macaque monkeys and humans.
• Participants passively listened to isochronous auditory sequences without specific tasks or training.
• Neural oscillations in delta, mu, and beta bands were analyzed to assess rhythm encoding and tracking.

Main Results:

• Both macaque monkeys and humans demonstrated delta-band neural oscillations that encoded and tracked auditory event timing.
• Mu- and beta-band oscillations in both species revealed the processing of accentuation patterns within the rhythmic sequences.
• These findings indicate convergent neural mechanisms for processing temporal regularities in the acoustic environment.

Conclusions:

• Macaque monkeys and humans show similar neural encoding and dynamic attending to auditory temporal regularities.
• This convergence suggests a shared phylogenesis of rhythm cognition, extending beyond vocal learning species.
• The study bridges a gap in understanding the evolutionary trajectory of rhythm processing abilities.