Photos by: Chino (August 2017)
Research in the Brain Plasticity and Neuroimaging Laboratory focuses on cognitive neuroscience of human memory and brain plasticity mechanisms.
Exercise, fitness and memory
Funded by the National Institute on Aging, the Brain Plasticity and Neuroimaging Laboratory is currently investigating the effects of aerobic exercise and cardio-respiratory fitness on brain function and structure.
Recently, we have shown that “Brain-Derived Neurotrophic Factor” (BDNF), a putative marker of synaptic plasticity, and cardio-respiratory fitness interactively predict recognition memory performance in young adults. Participants underwent a fitness test on the treadmill (see photo, above). During the treadmill test we measured the content of oxygen and carbon dioxide in our participants’ breath to determine maximum oxygen uptake (VO2 max) during exercise as a measure of their cardio-respiratory fitness. On a separate day, we took a blood sample to measure protein levels of BDNF in blood serum. During that day, participants also underwent several memory tasks. We found a negative correlation between serum BDNF and recognition memory accuracy. Cardio-respiratory fitness moderated the relationship between serum BDNF and recognition memory accuracy: for lower fit people, lower serum levels of BDNF were associated with better memory (negative correlation), while for fit people, higher serum levels of BDNF were associated with better memory (positive correlation). This complex relationship between BDNF, fitness, and recognition memory accuracy is illustrated in the figure below.
The medial temporal lobes and working memory
Another main research theme in the lab revolves around the role of the hippocampus and medial temporal cortex in working memory maintenance paradigms. In particular, we are examining under what conditions do medial temporal lobe regions show sustained activity during the delay period when stimulus input is absent. Most recently we started examining the specific contributions of hippocampal subfields to these working memory maintenance paradigms using high-resolution fMRI (Nauer et al., 2015; Schon et al., 2015).
Previous neuroimaging work from our lab and others support a role for the medial temporal lobe memory system in maintaining novel stimuli over brief working memory delays and suggest delay period activity predicts subsequent memory (e.g. Schon et al., 2004). Using high-resolution fMRI we have recently shown that delay period activity in the parahippocampal cortex, perirhinal cortex, and hippocampus (subiculum, extending into dentate gyrus/ CA3 and CA1) showed increased activity with increasing memory strength (Nauer et al., 2015), and that delay period activity in parahippocampal, entorhinal, and perirhinal cortex but not hippocampus showed increased activity during the working memory delay with greater working memory load (Schon et al., 2015). Together, this work supports computational models on the role of persistent spiking for both working memory maintenance and episodic memory encoding.