Cross Country Collaboration

Yes, those wires are electrified...

This past Saturday, I completed the 11 mile/22 obstacle course of the Chicago Tough Mudder.

We  survived!

The very next day, I left the country for Lübeck, Germany.

Situated along the Baltic Sea, Lübeck was once a powerhouse of the Hanseatic League. 

My head is still spinning from the quick turn around! It's surreal to be sitting at a new desk at the Universität zu Lübeck, and yet be working on a project that I've had on my to-do list for months. Sometime earlier this year, my advisor broached the topic of collaborating with Dr. Heldmann & Dr. Münte on a sleep fMRI project. Of course, I immediately volunteered myself and started working on the study design, along with another graduate student from my lab. However, I'm the first of the two of us to make it to Lübeck. My lab mate wont join me in Germany for another 2 weeks, by which time I hope to have finished piloting and be ready to move into data collection.

Most of my time so far has been dedicated to finding the appropriate stimuli for German participants. We piloted the behavioral aspects of the study in Chicago but it seems famous locations to us aren't nearly as well known here. That being said, most of the preparation I did at Northwestern has ended up being very helpful.

My new ride for the next month, she's old but strong!

Our next step will be to set up everything in the fMRI scanner and make sure we have our timing down. While piloting a few different sequences, I'll finally get to be the participant in the scanner! After all these years (5 years!) of being involved with imaging research, I'll finally get to take a peek at my brain! I can't tell you how exciting that is to me! And after we sort out how we will be collecting the brain images, we'll get right to the piloting phase!

But that's looking pretty far ahead. I haven't even been in Lübeck for a full week yet. So far, I've managed to figure out the grocery store and purchased an old bicycle so I can bike to work rather than taking the bus. So for my immediate future, my current plan is to finally explore the city this weekend and enjoy the fact that I'm living abroad!

What should happen to memory for events that occur within an emotional context?

Before addressing what happens to memories within an emotional context, I would first like to argue that there is no such thing as not having an emotional context during encoding or retrieval of memories. We may not always have a strong valence for everything that happens in our lives, but we are constantly experiencing emotion of some sort. Whether that experience is low-level like boredom or fatigue, or high level such as in deep sorrow or great joy, I cannot imagine a time where I have not experienced some mood. But for the sake of argument, I will focus on memories that occur during a strong emotional context.

            According to current memory literature, both positive and negative memories are better encoded than less emotionally salient experiences. Based on fMRI studies, (among other mechanisms) this deeper encoding is most likely due to amygdala activation- both for positive and negative memories. In a 2006 study by Kensinger and Schacter, they found activation of the amygdala during encoding for positive and negative items. This activity later predicted recall for these emotionally salient items. However, this effect did not extend beyond highly emotional items. In keeping with my earlier statement, I would argue that the amygdala actually was engaged even during the more neutral items, but that the activation was so weak that it could not be picked up in the fMRI BOLD signal. In any case, this research demonstrates that the limbic system, and the amygdala in particular, are more active during emotionally charged situations and allow for deeper encoding.

It makes evolutionary sense that emotionally engaging experiences (especially negative ones) should be better encoded. It’s beneficial for an organism to remember to avoid negative experiences that hurt its chance of survival, and positive experiences should be better remembered in order to seek out similar beneficial situations. Thus, it is unsurprising that highly emotional memories engage neural systems beyond the medial temporal lobe.

However, extreme mood at memory retrieval can occasionally be detrimental. In a 2005 research study, researchers found that inducing a positive mood during recall led to more false memories in the Deese-Roediger-McDermott paradigm. However, inducing negative mood during recall did not show this effect. This research demonstrates that while heightened emotion during encoding can be overall beneficial, that same state during retrieval ends up causing people to falsely identify lure items as old. Thus, extreme emotion can be a double-edged sword when it comes to memory.

Works Cited:

Guastella, A. J., Mitchell, P. B., & Mathews, F. (2008). Oxytocin enhances the encoding of positive social memories in humans. Biological psychiatry, 64(3), 256-258.

Kensinger, E. A., & Schacter, D. L. (2006). Amygdala activity is associated with the successful encoding of item, but not source, information for positive and negative stimuli. The Journal of Neuroscience, 26(9), 2564-2570.

Storbeck, J., & Clore, G. L. (2005). With sadness comes accuracy; with happiness, false memory mood and the false memory effect. Psychological Science, 16(10), 785-791.

Why does memory change as we age? What changes?

As the baby boomer generation begins to enter seniority, concerns over mental performance for that age group are drastically increasing. Supposed brain training games like luminosity are attempting to cash in on this generational concern, but how is memory actually changing as the brain ages? Research seems to indicate that while episodic and source memories are affected by normal aging, semantic and procedural memory stay rather intact. Scientists believe this is due to how different regions of the brain atrophy during aging.

For example, Nyberg and colleagues found that episodic recall varied according to age but that semantic memory did not show this negative relationship. Thus older adults might struggle with remembering if they took their vitamin supplements that morning, but seemed to have no problem identifying the current president. In addition, memories for how to carry out actions seem completely spared. In studies using animal models, researchers found that aged animals performed equally well on an obstacle course compared to the younger animals (as long as gross motor control was normalized across groups). This explains why my 62-year-old mother is one of the best nurse anesthetists at her workplace, even when she might feel that some of her memory is eroding.

So why aren’t all memories made equal with respect to aging? Shouldn’t all types of memory decline equally as we age? Region-specific atrophy seems to be one of the key components in this dissociation longevity between the types of memories. In an imaging study conducted by Yonelinas and colleagues, healthy older adults showed reductions in hippocampal volume when recollection was diminished. Meanwhile recognition performance was dependent on entorhinal volume. These regions of the brain, found in the medial temporal lobe, tend to decrease in volume to a greater extent during aging than other regions. Whether these volume changes are due to the dying-off of neurons or reduction in synaptic connections, this seems to be a major cause of memory complaints in older adults.

So it is rather unfair to say that memory declines as we age, when not all memory is created equal. It is noticeable in daily life to recognize that you can’t call to mind where you met someone or how to use a computer function that your children just taught you. It is not immediately obvious that your memory of how to drive a car or ride a bike is still almost completely intact. I believe this is due to our limited connotation of the word ‘memory.’ When taking all forms of memory into account, healthy aging does not cause nearly the impairment that might be felt by an older adult. Because we rely so heavily on episodic and source memory in our social lives, we might not realize the multitudes of semantic and procedural memories that have been spared. Maybe brain-training games are effective, but it is important to also remember that an aging mind isn’t deficient in all memory types and that much expertise is actually spared.

Churchill, J. D., Stanis, J. J., Press, C., Kushelev, M., & Greenough, W. T. (2003). Is procedural memory relatively spared from age effects?.Neurobiology of Aging, 24(6), 883-892.

Nyberg, L., Bäckman, L., Erngrund, K., Olofsson, U., & Nilsson, L. G. (1996). Age differences in episodic memory, semantic memory, and priming: Relationships to demographic, intellectual, and biological factors. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 51(4), P234-P240.

Yonelinas, A. P., Widaman, K., Mungas, D., Reed, B., Weiner, M. W., & Chui, H. C. (2007). Hippocampus, 17(11), 1134-1140.

Memory in the aging brain: doubly dissociating the contribution of the hippocampus and entorhinal cortex.