N-Methyl d-aspartate receptor hypofunction reduces steady-state visual-evoked potentials

Area of Science:

• Neuroscience
• Psychiatry
• Computational Neuroscience

Background:

• Dynamic neural coordination is crucial for cognitive function and is often impaired in neuropsychiatric disorders.
• Schizophrenia (Sz) is associated with reduced steady-state visual-evoked potentials (SSVEPs), a measure of large-scale neural rhythmic responses.
• Hypofunction of the N-methyl-D-aspartate receptor (NMDAR) is a leading hypothesis for the pathophysiology of schizophrenia.

Purpose of the Study:

• To investigate whether NMDAR hypofunction can explain the observed deficits in SSVEPs in schizophrenia.
• To experimentally test the hypothesis that impaired NMDAR function leads to reduced neural coordination.

Main Methods:

• Steady-state visual-evoked potentials (SSVEPs) were recorded from the primary visual cortex of nonhuman primates using multielectrode arrays.
• NMDAR hypofunction was induced by administering a subanesthetic dose of ketamine, an NMDAR antagonist.
• Control sessions involved saline injections.

Main Results:

• Ketamine-induced NMDAR hypofunction significantly reduced SSVEPs in nonhuman primates.
• This reduction in neural coordination occurred across a broad frequency range (5–40 Hz), consistent with findings in individuals with schizophrenia.
• The results demonstrate a direct link between NMDAR hypofunction and impaired rhythmic neural activity.

Conclusions:

• NMDAR hypofunction plays a critical role in generating the altered coordinated neural activity observed in schizophrenia.
• These findings provide experimental support for the NMDAR hypofunction hypothesis of schizophrenia.
• This study highlights the utility of experimental models in understanding neural deficits and developing treatments for neuropsychiatric diseases.