Human brain shifts gears based on season

The human brain doesn’t work at the same level all through the year, and tends to peak and dip in terms of sustained attention and working memory, a new study on Seasonality in human cognitive brain responses suggests.

For the study, a team of 16 researchers led by Pierre Maquet and Gilles Vandewalle at the University of Liege, Belgium, did research on 28 healthy volunteers (14 males and 14 females), all around the age of 21 years. The cognitive functions of 28 volunteers were recorded at different points in a calendar year, and researchers observed very varied brain activity dictated by seasonal patterns. The research focused on changes in areas of sustained attention, which were at their highest during the summer, while working memory recorded peak performance around the autumn months. (Read more here)

“Daily variations in the environment have shaped life on Earth, with circadian cycles identified in most living organisms. Likewise, seasons correspond to annual environmental fluctuations to which organisms have adapted. However, little is known about seasonal variations in human brain physiology," say the authors.

To rule out any impact of a person’s individual daily routines and the surroundings they live in, the volunteers stayed in the lab for 4.5 days at each step of the study, which included a 42-hour sleep deprivation cycle in a dimly lit sound-proof room with no time clues. After their daily senses were theoretically wiped clean and they had a full night’s sleep for their system to recover, they were asked to complete a sustained attention task and a function task. At this point, the researchers monitored individual brain activity using functional magnetic resonance imaging (fMRI), which showed the parts of the brain that were active based on changes in blood flow, indicating fired-up nerve cell activity.

It was at this point when researchers noticed differing patterns of active brain areas, according to the time of the year when the tests were done. During working memory tests, the frontopolar areas were most active in the fall season and were closest to idle in the spring season. For sustained attention tests, the thalamus part’s activity peaked during the summer months, and dipped in the winter months.

Researchers say that while the differences in brain activity did not hinder the participants’ overall performances, the brain activity mapping does suggest that different areas of the brain kicked into gear to complete the tasks, based on the season. This research is still in its early stages, but could at least provide some credibility to the previously mooted point of how seasons impact human brain activity—something that had earlier been brushed aside.

The next step for the researchers is to understand how biochemical changes and specific seasonal cues, such as temperature, humidity, and the length of the day also have an impact on brain activity.