In a recent study on mice, it was discovered that neurons in the suprachiasmatic nucleus (SCN), the brain's 24-hour timekeeper buried inside the hypothalamus, cooperated with one another to adjust to varying amounts of daylight. Both individual cells and the network as a whole changed as a result. According to the amount of light each day, important neurotransmitters' expression and mixture change.
We already know that changes in the SCN can impact how the paraventricular nucleus (PVN), a brain area located inside the hypothalamus that aids in controlling stress, metabolism, the immune system, biological growth, and other processes, and functions.
Researchers have now discovered a biological connection between daylight and human behavior." We revealed novel molecular adaptations of the SCN-PVN network in response to day length in adjusting hypothalamic function and daily behavior," neuroscientist Alessandra Porcu from the University of California San Diego, said.
The SCN, which controls the circadian rhythms that have a 24-hour cycle, is a component of the brain's timekeeping processes in both mice and humans. The retina's unique photosensitive cells regulate the SCN and transmit data about the amount of light present and the length of the day.
What is unclear, and this work provides significant insight into, is how the SCN's relatively small subset of 20,000 or so neurons respond to information about day duration. The treatment of health issues like SAD as well as other disorders where light is employed as a therapeutic option may benefit from learning more about this.
The neurotransmitters neuromedin S (NMS) and vasoactive intestinal polypeptide (VIP) were found to change in the mice, and these changes could be controlled to modulate network activity in the PVN.
In other words, we're coming closer to being able to control how much or little light we react to.
Though there are many parallels between the mouse and human brains, making mice appropriate test subjects, this research is still in its early stages. It is still unknown whether human neurons behave exactly the same way.
But by expanding on earlier research, the results might suggest fresh approaches to the use of light therapy in the treatment of neurological illnesses. The research team hypothesizes that the mechanism they've found could also affect our "remember" of how much daylight to anticipate as the seasons change.
The study is an illustration of how researchers can use earlier discoveries to delve farther, into the level of molecular mechanisms. Examining if the same mechanisms operate in the human brain will be one of the following steps.