Research Projects and Questions

Research in the Memory & Brain Lab at the University of Nevada investigates how we remember information over a short amount of time. This ability is called 'Working Memory' and we use it as a mental workspace. Our lab is interested in understanding how the brain creates working memory. To answer our questions we use all available experimental approaches: psychophysics, neuropsychology, neuroimaging (EEG, fMRI), and neurostimulation (TMS, tDCS/tACS). We welcome collaboration and we are always looking for participants. Below, several active projects are described in more detail.

 

Here is a link to our peer-reviewed papers on PubMed. 

 

Please contact mberryhill@unr.edu if you would like a reprint. Please contact us if you are interested in participating or learning more about our work: mblab@unr.edu, (775)682-8667.

 

1) What are the lasting cognitive consequences of concussion?

Many of us have hit our heads before, and millions of us have had concussions (mild traumatic brain injury: mTBI). Most people feel better quickly and return to normal activities. However, it is an open question whether people are fully rehabilitated or whether they have lasting impairment as a result of a history of concussion. In our studies of working memory, we see that undergraduates with a history of mTBI perform worse than their colleagues with no such background. These otherwise healthy, successful students are significantly impaired at holding on to 3-items for .5 sec (Arciniega et al., 2019; 2020; 2021). Thus far, in 7 studies, we see the same behavioral deficit in ~200 undergrads with a history of concussion. Surprisingly, these students are ~4 years post-injury. In other words: There are lingering cognitive deficits in the chronic mTBI undergraduate population. 

Current Activities: We have a lot of questions! We want to understand the sources of heterogeneity in outcomes: some people appear fine whereas others are impaired. The data we collected were retrospective. We are now probing longitudinal data collected prospectively to better understand what predicts long-term outcomes. We are looking for neural signatures of mTBI using EEG connectivity to identify common abnormalities of neural communication. Our long-term goal would be to develop interventions that restore behavioral performance.

We collaborate with Dr. Nicholas Murray, PhD, a colleague in Community Health Sciences at UNR. We also work with Drs. Stephen Lane and Windy McNerney, scientific advisors to the Tahoe Institute for Rural Health Research. 

 

2. Can working memory be improved? 

Working memory can only hold a few items. Often, people report working memory lapses: finding themselves staring blankly at the fridge, wandering around looking for the sunglasses on their heads, returning to the starting point to bring to mind the destination... 

There are many commercial products providing training programs to improve working memory, but with modest successes. We are combining working memory with neurostimulation (tDCS). We found that older adults hold onto their training benefits longer if they also got tDCS (link to paper 1, 2, 3). In younger adults, we are beginning to understand how tDCS enhances frontal-posterior connectivity (link). We recently reported, however, that sometimes training does not even improve performance on a practiced task (Shires et al., 2020), leading us to think about the role of motivation.

 

3. What is the nature of ‘internal’ attention? How does previous exposure change our visual experience?

We are always shifting our attention among the items in front of us. For example, when you look around, you may see your phone, books, trees, your phone, people, your phone, pictures, etc. Importantly, we can also shift attention between items we’ve already looked at. Some of these items enter working memory. Based on your current goals, you may need to shift among these items to accomplish the task. For example, imagine you are looking for your keys - you may mentally retrace your steps by shifting your attention through the places you recently traversed. We are interested in characterizing similarities and differences between perceptual attention (attending to items in your presence) and internal attention (attending to items no longer in your presence).

Current Activities:  Objects in our environment are not of equal merit over time. For example, keys and wallet are supremely valuable until they are in your pocket, then perhaps you look for your coffee mug before leaving home. We are also interested in how we retain patterned associations over time.