Ir-rat-ability and Anxiety in the Amygdala Team Four: Megha - PowerPoint PPT Presentation

Ir-rat-ability and Anxiety in the Amygdala Team Four: Megha Andrews, Madlyn Kates, Christine Lu, Katherine Miao, Archana Raghunath, Angeli Sharma, Grace Shen, Michael Tai, Mary Tresvalles, Elena Wei, Destiny West, Audrey Zhou

Anxiety/Anxiety Disorders ● Anxiety-like behaviors vs. anxiety disorders ● One of the most prevalent classes of mental illness ● Fear, uneasiness, dread, irritability ● GAD, Social Anxiety, Phobias, PTSD

Purpose INVESTIGATE THE ROLE OF THE AMYGDALA/AMYGDALOID COMPLEX IN ANXIETY LIKE BEHAVIORS Predator odor used as model for anxiety disorders

Why are we interested in the amygdala? ● Motivation, making decisions, and processing emotions . ● Area of interest: corticomedial amygdala (CMA).

Phasic VS Sustained Fear: Phasic Fear Sustained Fear Fades quickly Pervasive Visible Threat Potential Unseen Danger

The amygdala receives input from multiple olfactory systems:

Experiments Open Maze Acoustic Startle Test Electrophysiology

Experiment 1: Maze ● Analyze aversion ● Predator pheromone odors, Preferential Pheromone, & Control Odor

Experiment 1: Maze Procedure

Experiment 1: Maze Data * * The rats * surprisingly spent more time in the zones containing the predator pheromones.

Experiment 1: Maze Data * * * * In the general the rats moved in greater speeds in the presence of the odors.

Experiment 1: Maze Data * On average the rats * stayed closer to the * * points containing the predator odors. Overall it seems that the rats displayed the most aversion to the pheromones from the cat urine and fox urine.

Experiment 1: Maze Results ● Rats exhibited greater time in zone, faster speed, and lesser distance from point for cat urine and fox urine ● No significant difference in zones with propyl butyrate ● Does not show aversion to rat and cat urine but rather suggest that rats investigated the odorants

Experiment 2: Startle Test ● Monitor the rats’ acoustic startle responses ● Compare the standard, “baseline” response to when the pheromones/ odorants are released (presence of anxiety).

Experiment 2: Startle Procedure 3 Handling Sessions Baseline Test 1 Baseline Test 2 Baseline Test 3 Olfactory Startle Test 1 Olfactory Startle Test 2 Baseline Test 4 Olfactory Startle Test 3 Olfactory Startle Test 4

Experiment 2: Baseline Startle Test Procedures 3 Handling Sessions ▪ Purpose) To test equipment as well as record initial startle responses of Baseline Test 1 each subject without odor present Baseline Test 2 ▪ Acclimation period of 2 minutes ▪ 40 sound pulses of varying intensities Baseline Test 3 played in a pseudo-random order Olfactory Startle Test 1 ▫ Played in 15 second intervals ▫ Order kept constant for all Olfactory Startle Test 2 subjects Baseline Test 4 Olfactory Startle Test 3 Olfactory Startle Test 4

Experiment 2: Baseline Startle Data shows that startle amplitude is influenced by pulse intensity. Habituation is evident by the decreasing amplitude. * *

Experiment 2: Baseline Startle Results The decrease in response across sessions shows evidence of habituation

Experiment 2: Olfactory Startle Test Procedures ▪ Odorants) fox urine, cat urine, female rat 3 Handling Sessions urine, propyl butyrate ▪ Acclimation period of 5 minutes Baseline Test 1 ▪ 70 sound pulses of 95 dBA played in 15 second intervals Baseline Test 2 ▫ On 31st sound pulse, odorant is first Baseline Test 3 introduced ▪ Every 4th sound pulse after 31, odorant is Olfactory Startle Test 1 reintroduced into chamber (35th pulse, Olfactory Startle Test 2 39th pulse, etc.) ▪ Order of odorants counterbalanced to Baseline Test 4 avoid repeated testing Olfactory Startle Test 3 Olfactory Startle Test 4

Trial Structure 5 minute acclimation 30 baseline trials 40 odorant trials

Olfactory sessions represented as a percentage of the baseline. Cat and female rat urine showed similar results as the control.

Fox urine was the only odorant that produced a noticeable effect.

Experiment 2: Olfactory Startle Conclusion ● Cat urine and female rat urine cause no significant anxiety induced response. ● Propyl butyrate (the control odorant) causes a significant increased response which indicates that there was another factor involved. ● Fox urine data is evident of a phasic fear response.

Experiment 3: Electrophysiology ▪ Objective: ▫ Record electrical activity of neurons in the corticomedial amygdala ▫ Determine its connection to pheromone processing

Experiment 3: Electrophysiology Procedure Amplifier Electrode E Thermocouple Oscilloscope Olfactometer Computer ● Cat urine ● Fox urine

Experiment 3: Electrophysiology Procedure

Experiment 3:Electrophysiology Procedure Amplifier Electrode E Thermocouple Oscilloscope Olfactometer Computer ● Cat urine ● Fox urine Data Analysis

Analysis of electrophysiology data yields two distinct waveforms. Unit A Unit B Crest of action potential Trough of action potential

Results from a previous experiment that would corroborate our hypothesis that the detected cells process specific odors.

Our results did not match. Neither control nor experimental odors elicited an obvious response from the detected cells.

Experiment 3: Electrophysiology Conclusion ❖ Sample Cell ➢ showed both odor responsivity and specificity ❖ Our 3 Tested Cells ➢ Neither odor specificity or responsivity ❖ Sample size did not permit an accurate estimation of the population of corticomedial amygdala cells.

Conclusion ❖ Most of the results did not align with our hypothesis, that predator pheromones would have an effect on the neurons of the corticomedial amygdala in processing olfactory information. ❖ Main Findings ➢ Open Maze ➢ Acoustic Startle ➢ Electrophysiology ksdksd ❖ Possible Sources of Error ❖ Future Implications

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Acknowledgements ● Dr. Graham Cousens ● Runi Patel ● Dr. Cassano and Dr. Surace ● Our Sprague-Dawley rats: ○ (MAZE) Elliot the Scrub Rat, Simon, Michael, George, Russell, Mercutio, Remy ○ (STARTLE) Ace, Felix, Tucker, Mrs. Frisby, Stitch, Jerry, Finnegan, Julius ○ (ELECTROPHYSIOLOGY) Ratsby, Sirius RIP ● Funders & Supporter of NJGSS: ○ AT&T, Bayer Healthcare, Independent College Fund of New Jersey, Johnson & Johnson, The Overdeck Family Foundation, NJGSS Alumnae and Parents, Corporate Matching Funds, The State of New Jersey, Board of Overseers, New Jersey Governor’s School