Ultra-high Field fMRI Reveals Effect of Ketamine on Vocal Processing in Common Marmosets.

Summary

Ketamine's impact on brain activity reveals striking parallels between primate vocal processing and schizophrenia symptoms. Using advanced fMRI technology, researchers observed how ketamine affects marmoset monkeys' brain responses to various sounds. The drug significantly reduced activity in auditory processing regions, particularly when hearing vocal calls, with notable changes in brain areas linked to schizophrenia symptoms.

Abstract

Auditory deficits are a well-known symptom in neuropsychiatric disorders such as schizophrenia. The noncompetitive N-methyl-d-aspartate receptor antagonist ketamine has been used to model sensory and cognitive deficits in nonhuman primates, but its whole-brain effects remain largely unknown. Here we employed ultra-high field functional magnetic resonance imaging at 9.4 T in awake male and female marmoset monkeys (Callithrix jacchus) to compare brain activations to conspecific vocalizations, scrambled vocalizations, and nonvocal sounds following the administration of a subanesthetic dose of ketamine. Our findings reveal a broad suppression of activations across auditory regions following ketamine compared with saline. Additionally, we observed differential effects depending on the type of sound, with notable changes in the mediodorsal thalamus and anterior cingulate cortex, particularly during the processing of vocalizations. These findings suggest a potential overlap between the effects of ketamine and neural disruptions observed in schizophrenia, particularly affecting vocalization processing.

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