In the Journal of Neuroscience, members of the Griffith Lab found that memory impairments can result from disruptions in the release of the peptide Pigment-dispersing factor (PDF). PDF aligns the brain’s time-keeping mechanism to the correct time of day.
Upsetting the brain’s timekeeping can cause cognitive impairments, like when jetlag makes you feel foggy and forgetful. These impairments may stem from disrupting a protein that aligns the brain’s time-keeping mechanism to the correct time of day, according to new research in fruit flies published in JNeurosci.
The brain contains ‘clock’ neurons that collectively mold circadian behaviors and link them to cues from the environment, like light and seasonal changes. In fruit flies, the peptide Pigment-dispersing factor (PDF) is released from the clock to both synchronize the activity of the clock neurons and to drive time-based behaviors like mating and sleep. PDF may also underlie memory formation, explaining the cognitive dysfunction that occurs when the clock is desynchronized from the environment.
Flyer-Adams et al. tested how well fruit flies with a functioning core clock, but lacking the PDF output signal, could learn. They found that without PDF signaling, flies had severely impaired memory. Interestingly, memory regulation by PDF likely occurs without direct signaling to the main memory structure of flies. Their results suggest that PDF from the clock may promote normal memory throughout the day by acting as a timestamp to learning. The VIP pathway in humans may play a similar role.
Publication:
Regulation of olfactory associative memory by the circadian clock output signal Pigment-dispersing factor (PDF).
