Functional development of the dorsolateral prefrontal cortex: an analysis utlizing reversible cryogenic depression.

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Primate Behavior

Background:

• The dorsolateral prefrontal cortex (dlPFC) is crucial for executive functions.
• Understanding the developmental trajectory of dlPFC function is vital for cognitive neuroscience.

Purpose of the Study:

• To investigate the functional maturation of the dlPFC in rhesus monkeys during postnatal development.
• To determine the developmental timelines for spatial delayed-response and delayed-alternation tasks.

Main Methods:

• Local hypothermia was used to temporarily inactivate the dlPFC in rhesus monkeys of varying ages (9-36 months).
• Monkeys performed spatial delayed-response and spatial delayed-alternation tasks under hypothermic and normothermic conditions.
• Thermal gradients were mapped to ensure accurate and consistent cooling across age groups.

Main Results:

• Delayed-response performance showed age-dependent deficits, with younger monkeys (9-16 months) exhibiting no loss, while older monkeys (34-36 months) showed significant decrements (21-25%).
• Delayed-alternation performance was impaired as early as 8.5 months, but maximal deficits were observed in older monkeys (≥33 months).
• Behavioral differences were not due to technical variations in cooling, as thermal gradients were similar across ages.

Conclusions:

• Functional maturation of the dlPFC is a protracted process in rhesus monkeys, extending over several years postnatally.
• Spatial delayed-response and delayed-alternation are dissociable dlPFC functions with distinct maturation rates.
• Neurobehavioral analysis using reversible inactivation is a valid approach for studying regional brain maturation.