Have you ever been hit on the head? How long it’s been since you did? Blows to the head are not uncommon, they can happen in sports, accidental falls, fights, and in plenty of other ways. Heck, they can happen sometimes just because you crouch down looking for something and then miscalculate your distance when you stand back up, can’t it?
Thankfully, most of the time nothing more than an ouch! moment happens. But on some occasions, they can lead to a concussion or mild traumatic brain injury (mTBI). As they are “mild” (it’s even in the title) any cognitive effects are considered fleeting and no medical treatment is administered.
But is it possible that there are long-lasting effects on cognition after mTBI? This is the question that Arciniega, Kilgore-Gomez, Harris, Peterson, McBride, Fox, and Berryhill asked in their paper published in the Psychonomic Society journal Attention, Perception & Psychophysics. To explore this topic, the researchers compared the performance of college students with and without a history of mTBI using working memory (WM) tasks across four experiments.
For illustrative purposes, imagine yourself as a participant. You’re an undergraduate and volunteer to take part in the study. Your first task is to report whether you had had a history of mTBI. Let’s say that you’re among the 30-35% of the students who reported at least one such episode. You perform normally in your life as a busy and happy undergrad and rarely give your mTBI much thought. After all, it’s likely that you didn’t undergo any medical treatment for it, and it’s also likely that you don’t feel like anything is amiss.
Here comes the challenge! [music intensifies]. Can you remember the color and positions of the squares? Try it in the video below. The trial starts with a cue, so look for the white arrowhead because this will tell you which half of the screen to attend to. Then, remember the colored squares that appear on that half. When the test probe comes, you would (if this were the real task) hit the “o” key for “old” (same colors) and “n” for “new” (different colors).
[videopress 7iT46C9C]
Image doing that for hundreds of more trials, and then you’ll be in the same company as the participants who took part in the research conducted by Arciniega and colleagues. The figure below shows the task schematic of what’s referred to as a “change detection visual working memory task” that was used in the first three experiments.
How would your performance compare to other participants?
Arciniega and colleagues found, at the group level, students with a history of mTBI perform worse than those without when the set size is 3, as shown in the figure below. In the figure, the k value is the set size multiplied by the difference of the hit and false alarm rates. This suggests mild deficits in working memory.
In follow-up experiments, the researchers explored whether such deficits could be due to differences in, for example, motivation by adding feedback to some of the trials. The results revealed a stable pattern: the deficits in performance can be detected when 3 squares are presented, and no evidence for the effects being due to motivation between the groups was found.
To explore whether the difficulty to retrieve information from memory accounted for the performance differences, in another experiment, the researchers manipulated retrieval demands by asking participants to keep in mind the location and orientation of lines, and after a delay, to either recognize whether a probe matched the observed stimuli, or to rotate it until it matched it. The schematic of the task in Experiment 4 is shown in the figure below. After a fixation cross, four lines with different orientations appeared, and, after a delay, the participants had to recognize whether the presented probe matched the stimulus (recognition) or to rotate it until it matched it (recall).
As shown in the figure below, the performance was lower for participants with a history of mTBI was still detected in both the recognition (top panel) and recall (bottom panel). The results, however, did not suggest that the performance differences could be due to the difficulty of the retrieval task.
What can we take home from this study? There are at least two key points to highlight:
1. It may be important to screen participants for a history of mTBI, as their cognitive performance may be characterized by subtle differences from an otherwise “neurotypical” population.
2. Long-term consequences of mTBI could persist over time, and that it is important to pay attention to it and maybe to strive to, according to the authors,
…develop restorative protocols across the mTBI survivor population, regardless of how highly functioning they are or how long since their injury.
The message that I’ll take from this study is to avoid getting knocked on the noggin.
Psychonomic Society’s article focused on in this post:
Arciniega, H., Kilgore-Gomez, A., Harris, A., Peterson, D. J., McBride, J., Fox, E., & Berryhill, M. E. (2019). Visual working memory deficits in undergraduates with a history of mild traumatic brain injury. Attention, Perception, & Psychophysics. https://doi.org/10.3758/s13414-019-01774-9
