Tag: Oral Session 4 CQ

Odor Concentration Change Sensing in Mice

Presenter(s): Antonio Munoz

Faculty Mentor(s): Avinash Singh & Matt Smear

Oral Session 4 CQ

Our brains are constantly tracking dynamic sensory information from our environment. Exactly how the brain computes sensory input over time is not fully understood. The mouse olfactory system provides a great model to study stimuli changes over time because mice utilize odor concentration changes for olfactory navigation. It is not understood how mice optimize sensory information for spatial navigation.

One of the mechanisms guiding odor localization involves changes in odor concentration (ΔC). The ability to track odor concentration gradients is critical for vertebrates like the mouse for survival.
Previous work in the Smear lab has revealed a population of neurons in the olfactory bulb that respond to dynamic stimuli changes. The neural activity in this population of neurons was sensitive to concentration changes in odor.

The brain somehow maintains a neural representation of odor across sniffs, and this is the behavior I want to observe. A behavioral representation of these ΔC neurons had previously not been studied before. By investigating ΔC tracking behaviors in mice, my goal is to relate the neural activity we see in this neuronal population with a behavioral representation in mice and increase our understanding of sensory optimization.

Effect of inter-stimulus interval duration and predictability on sensorimotor beta

Presenter(s): Ryan Leriche

Faculty Mentor(s): Nicole Swann

Oral Session 4 CQ

It is well established that the oscillatory beta band (13-30Hz)—a range of frequencies detected from electrical brain waves—modulate in a consistent manner during motor-response tasks over the sensorimotor cortex contralateral to movement. Studies have shown a myriad of parameters (e.g. movement certainty, grip type, response speed, etc.) that cause movement related beta band spectral power decreases. Purely visual stimulus processing studies have also shown analogous beta band suppression 300-500ms post-stimulus. Delayed-go tasks (a type of motor response task) start with an initial stimulus, the “fixation cue”, that indicates an upcoming movement. A subsequent cue, the “GO cue”, tells the participant to execute the experimental movement. The inter-stimulus interval (ISI) between these two stimuli is often jittered to prevent excessive movement related beta band suppression. If jittered, the beta oscillatory changes from visual stimulus may irregularly confound the beta power surrounding movement over these sub- second ISIs. To examine this, electroencephalography (electrodes that record electrical signals from the scalp), was recorded from 11 participants in a delayed-go task with modulations to the predictability and duration of the inter-stimulus interval. Across all participants, the averaged beta power had a strong negative correlation with the length of the varied ISI condition which ranged from 300-700ms. There was also a significant difference in the per subject average of beta power based on the predictability of go-cue presentation. These data suggest that future studies need to investigate the often ignored and possibly confounding interaction of stimulus timing and movement execution on electrophysiological measures.

Hemodynamics of Post-Exercise and Post-Passive Heat Stress Recovery Periods

Presenter(s): Cameron Colbert

Faculty Mentor(s): Christopher Minson & Michael Francisco

Oral Session 4 CQ

Recent research suggests that individuals exposed to heat stress chronically (e.g. sauna users) enjoy similar benefits as chronic exercisers. Many of exercise’s benefits are facilitated during the recovery phase, or the period of time following the cessation of exercise. By studying the cardiovascular responses during the recovery period following both heat stress and exercise, we can further explore clinically-relevant applications of heat therapy. This study seeks to compare the acute physiology of the recovery periods following exercise and hot water immersion (HWI). METHODS: 9 subjects (4 F, 5 M, age 22.4 ± 2.4 years) in random order exercised for 60 minutes at 60% VO2 peak and were immersed in 40.5oC water for 60 minutes on separate days. Measurements were made at baseline, during the interventions, and for 60 minute recovery period following both interventions. Heart rate, blood pressure, core temperature, and subjective measures were recorded every five minutes. Cardiac output, femoral and brachial artery hemodynamics were assessed using Doppler ultrasonography every 20 minutes. Skin blood flow was measured continuously during recovery. RESULTS: Brachial artery antegrade shear rate increased during HWI to a greater extent than exercise (p0.06). Skin blood flow following hot water immersion was significantly greater than that of post-exercise for the first 35 minutes of recovery (p<0.028). DISCUSSION: Many of the changes seen during the post-exercise recovery period that lead to beneficial cardiovascular adaptation are also seen during the post- immersion recovery period, suggesting hot water immersion may improve cardiovascular health.