Tag: Stimuli and Response

Optical Based Sensing of Shear Strain using Reflective Color Patterns

Presenter: Maryam Shuaib – Human Physiology

Faculty Mentor(s): Mike McGeehan, Keat Ghee Ong

Session: (In-Person) Oral Panel—Stimuli and Response, Poster Presentation

There is an increasing need to measure shear force in biomedical applications. Many shear force sensors exist, but are often impractical as they can be bulky, require large amounts of power, and are sensitive to electromagnetic interference. The goal of this project is to apply new optoelectronic sensing principles to measure shear strain. Optoelectronic sensors have various advantages including a smaller design that is able to measure multi-axial shear strain. This particular sensor functions through optical coupling of an LED that emits red, green, and blue (RGB) light, which is then reflected off of an adjacent surface displaying a color pattern consisting of randomized color pixels (Figure 1A). Shearing between these surfaces is measured using a photodiode, which senses changes in the RGB light intensities due to the shifts in the color pattern’s position. The purpose of this study was to compare the efficacy of various color patterns and classification algorithms to determine multi-axial shear strain. The optimal sensor configuration was found to be Pattern 3 (Figure 1B) with a Weighted K-Nearest-Neighbor algorithm with an accuracy of 98%, and a misclassification cost of 0.07 millimeters. The accuracy and robustness of the sensor-derived measurements, along with the practical and scalable design, support the use of this sensor in a multitude of biomedical applications.

Investigation of Training Methods Used for Mice to Perform Auditory Discrimination Tasks

Presenter: Sean Kyne – Biology

Faculty Mentor(s): Santiago Jaramillo

Session: (In-Person) Oral Panel—Stimuli and Response

The auditory system has a tremendous capacity to interpret all the surrounding sounds in the environment and help make sense of the world around us. To understand how our brains interpret and process complex sounds, we need a new method for studying auditory cognition. Researchers have created head-fixed rigs where mice run on a wheel while their head remains stationary and perform auditory discrimination tasks. This setting will allow us to study how the auditory system discriminates complex sounds using electrophysiological techniques that would be more challenging to apply in a freely-moving setting. Previous work in the lab suggests that it is more challenging to train mice in a head-fixed setting than in the more well-known freely moving setting. To improve our understanding of how to train head-fixed mice, they were trained to discriminate sounds of varying complexity. In each project, a new training protocol was implemented to increase our understanding of the best methods for training mice. The training protocols had varying success in teaching the task which provided helpful insights into teaching head-fixed mice auditory discrimination tasks.

Taking what was learned will allow us to teach mice more efficiently on future tasks using more complex sounds. Studying the methodology of how to train mice will allow for future experiments to use electrophysiological techniques to increase our understanding of the neural circuits used in auditory cognition.

The effects of ovariectomy and soy diet on vascular function in female C57BL6 mice

Presenter: Aleena Khurana − Human Physiology

Faculty Mentor(s): Ashley Walker, Mackenzie Kehmeier

Session: (In-Person) Oral Panel—Stimuli and Response

As people begin to live longer, studying age-related disease becomes more important. Age is a major risk factor for Alzheimer’s disease (AD), a prominent neurodegenerative disease, and other cardiovascular diseases; Females develop AD at much higher rates and all signs point to sex hormones. Estrogen drastically decreases post menopause, and it has been suggested that estrogen deficiency is a contributing factor to the sex differences seen in AD and other age-related diseases. The vascular system plays an important role in aging. A characteristic of aging in the vascular system is stiffening of larger arteries. Large artery stiffening is detrimental due to the increase in pulse pressure and stress associated with stiffening. Decreased estrogen activity results in increased production of reactive oxygen species (ROS), causing tissue damage and dysfunction. Elevated ROS and oxidative stress increase inflammation in the brain, further explaining the potential effects estrogen loss has in relation to such diseases. Soy also has been seen to be a protective factor against symptoms of age-related disease due to its role as a phytoestrogen, thus showing the potential importance of soy. This study aimed to explore the effects of estrogen depletion post menopause and the effects of a soy diet in relation with estrogen loss. We utilized a mouse model including ovariectomies to mimic estrogen loss post menopause and studied cognitive function, motor coordination, and vascular function.

Femoral Fracture Fixation Device to Wirelessly Monitor Real Time, in Vivo Strain

Presenter: Noah Greenblatt – Human Physiology

Co-Presenter(s): Walker Rosenthal

Faculty Mentor(s): Keat Ghee Ong, Salil Karipott

Session: (In-Person) Oral Panel—Stimuli and Response, Poster Presentation

Strain, a primary measure of the dynamic mechanical environment, is important with regard to patient aimed orthopedic treatment especially in minimizing complications that arise after certain bone fracture injuries. Currently, methods aimed at assessing the mechanical environment include external stimulating devices that fail to measure strain during normal gait patterns, and estimated parameters computed from different computational models which lack real-time data. With these limitations in determining real time load condition in bone fracture healing, we aimed to fabricate a bone fixation device that provided adequate mechanical stability to a healing bone fracture and measured strain present on the device in a rodent femur. This device transmits measurements wirelessly to a nearby computer for quantification of strain. Our results showed the ability to successfully measure local axial strain during functional loading on a rodent with a femur fracture. This device facilitates the study of mechanical strain and its role in bone healing in preclinical rodent fracture models. Most importantly, this device allows for future rehabilitation protocols that are evidenced-based and patient specific.

Pupillary Dilation Response to Changes in Sound Stimuli

Presenter: Temerity Bauer − Biology

Faculty Mentor(s): Santiago Jaramillo

(In-Person) Oral Panel—Stimuli and Response, Poster Presentation

To understand the world around us, the auditory system of our brains discriminates between different sounds to interpret our surroundings. Normally, simple sounds (like pure tones) are used to study the neural mechanisms for processing sounds by training animals. Training animals to discriminate between sounds is an arduous endeavor. Further, using simple sounds limits our understanding of how the brain interprets sounds of the complexity that is experienced every day. To address these problems, we developed a methodology to study sound discrimination in naive mice without training the animals by using pupillometry.

Changes in pupil size is one of the many responses to stimuli an animal can have. A study performed by Montes-Lourido et al. found pupil diameter changes correlate with an increase in motivation, effort and arousal in the brain in subjects (Montes-Lourido et al., 2021). Previous studies found changes in pupil sizes to sounds like pure tones and animal calls (Montes-Lourido et al., 2021). We hypothesized pupil responses would occur when the animal is presented with complex sounds that are found in nature. To study natural complex sounds, we first had to establish if pupillary dilation responses occurred to changes in simpler sounds like chords. We found that the pupils exhibited a pupillary dilation response to changes in frequency. Through this project, we determined pupillary dilation responses can be used as a method to study frequency discrimination in mice.