NOS1 ex1f-VNTR polymorphism influences prefrontal brain oxygenation during a working memory task

Area of Science:

• Neuroscience
• Genetics
• Cognitive Psychology

Background:

• Nitric oxide (NO) synthase, encoded by the NOS1 gene, plays a crucial role in neuronal signaling.
• A variable number of tandem repeats (VNTR) polymorphism in the NOS1 gene's exon 1f promoter region influences behavior and cognitive function.
• Specific NOS1 variants are linked to impulsivity, reduced verbal working memory, and schizophrenia risk.

Purpose of the Study:

• To investigate the impact of the NOS1 ex 1f-VNTR polymorphism on working memory.
• To examine how this genetic variation affects prefrontal cortex oxygenation during a working memory task.
• To test the hypothesis that homozygous short allele carriers exhibit distinct brain oxygenation patterns.

Main Methods:

• Studied 56 healthy subjects stratified into homozygous short and long allele groups for the NOS1 ex 1f-VNTR.
• Administered a letter n-back task (1-back, 2-back, 3-back) to assess working memory.
• Measured prefrontal cortex oxygenation changes (O(2)Hb) using functional near-infrared spectroscopy (fNIRS).

Main Results:

• Working memory load increased oxygenated hemoglobin (O(2)Hb) in the prefrontal and parietal cortices.
• Significant genotype-dependent differences in oxygenation were observed in the dorsolateral prefrontal cortex and parietal cortex.
• Short allele carriers demonstrated a greater increase in O(2)Hb during the n-back tasks compared to long allele carriers.

Conclusions:

• The NOS1 ex 1f-VNTR polymorphism influences working memory-related brain activity.
• Short allele carriers may exhibit a compensatory neural mechanism involving increased prefrontal and parietal cortex activation.
• These findings link NOS1 genetic variation to cognitive function and brain oxygenation patterns.