Prefrontal cortex activity induced by periodontal afferent inputs downregulates occlusal force

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Motor Control

Background:

• The prefrontal cortex (PFC) is crucial for cognitive functions including planning and decision-making.
• Periodontal sensory input influences PFC activity during motor tasks like maintaining biting force.
• Detailed understanding of the interplay between periodontal sensation, PFC activity, and motor task performance is lacking.

Purpose of the Study:

• To investigate the relationship between periodontal sensory input, prefrontal cortex (PFC) activity, and occlusal force generation during different biting tasks.
• To determine how changes in interocclusal distance affect PFC activity and biting force, particularly differentiating between incisor and molar occlusion.

Main Methods:

• Functional near-infrared spectroscopy (fNIRS) was employed to monitor changes in cerebral blood flow (CBF) in the PFC.
• PFC activity was measured during four distinct biting tasks involving central incisors and first molars at 5 mm and 10 mm interocclusal distances.
• Occlusal force was quantified during each task.

Main Results:

• Molar occlusion at a reduced interocclusal distance (BM-5 mm) showed increased PFC regional CBF compared to a larger distance (BM-10 mm).
• No significant difference in PFC CBF was observed between the two interocclusal distances for incisor occlusion (BI-5 mm vs. BI-10 mm).
• Mean occlusal force was significantly lower during molar occlusion with a reduced interocclusal distance (BM-5 mm) compared to a larger distance (BM-10 mm).

Conclusions:

• The PFC appears to decrease efferent signaling to motor units to reduce occlusal force when periodontal sensation is heightened due to reduced interocclusal distance.
• This suggests the PFC plays a role in regulating motor output based on somatosensory feedback, especially when relying on periodontal sensation alone.