Resting brain activity varies with dream recall frequency between subjects

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Sleep Research

Background:

• The neural basis of dreaming remains largely unknown.
• Lesions in the temporoparietal junction (TPJ) and medial prefrontal cortex (MPFC) correlate with a complete cessation of dream reports.
• These brain regions are part of the default mode network, implicated in the 'forebrain dream-on' hypothesis.

Purpose of the Study:

• To investigate the cerebral underpinnings of dream recall frequency (DRF).
• To test the 'forebrain dream-on' hypothesis by examining brain activity in individuals with high versus low DRFs.
• To explore the role of TPJ and MPFC in both dreaming during sleep and dream recall during wakefulness.

Main Methods:

• Regional cerebral blood flow (rCBF) was measured using [(15)O]H2O positron emission tomography.
• Participants included healthy subjects with high and low dream recall frequencies.
• Brain activity was assessed during wakefulness (rest) and different sleep stages (REM, N2, N3).

Main Results:

• High recallers exhibited significantly higher rCBF in the TPJ during REM sleep, N3, and wakefulness compared to low recallers.
• High recallers also showed higher rCBF in the MPFC during REM sleep and wakefulness.
• These findings indicate distinct resting-state brain activity patterns between high and low dream recallers during both sleep and wakefulness.

Conclusions:

• The results support the 'forebrain dream-on' hypothesis, suggesting TPJ and MPFC are crucial for dreaming.
• These regions appear to be involved in dream production and/or memory encoding during sleep.
• Increased TPJ and MPFC activity may enhance dream imagery, memory encoding, and intrasleep wakefulness for better dream recall.