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

Ir-rat-ability and Anxiety in the

Amygdala

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

● Analyze aversion

● Predator pheromone odors, Preferential

Pheromone, & Control Odor

Experiment 1: Maze

Experiment 1: Maze Procedure

The rats

surprisingly spent

more time in the

zones containing

the predator

pheromones.

Experiment 1: Maze Data

* * *

Experiment 1: Maze Data

In the general the

rats moved in

greater speeds in

the presence of the

odors.

* * * *

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 Data

* * * *

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

▪ Purpose) To test equipment as well

as record initial startle responses of

each subject without odor present

▪ Acclimation period of 2 minutes

▪ 40 sound pulses of varying intensities

played in a pseudo-random order

▫ Played in 15 second intervals

▫ Order kept constant for all

subjects

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 Data shows that startle amplitude is influenced by pulse intensity.

Habituation is evident by the decreasing amplitude.

* *

The decrease in response across sessions shows

evidence of habituation

Experiment 2: Baseline Startle Results

Experiment 2: Olfactory Startle Test Procedures

▪ Odorants) fox urine, cat urine, female rat

urine, propyl butyrate

▪ Acclimation period of 5 minutes

▪ 70 sound pulses of 95 dBA played in 15

second intervals

▫ On 31st sound pulse, odorant is first

introduced

▪ Every 4th sound pulse after 31, odorant is

reintroduced into chamber (35th pulse,

39th pulse, etc.)

▪ Order of odorants counterbalanced to

avoid repeated testing

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

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

Olfactometer ● Cat urine

● Fox urine

Thermocouple

Electrode

E

Oscilloscope

Amplifier

Computer

Experiment 3: Electrophysiology Procedure

Experiment 3:Electrophysiology Procedure

Olfactometer ● Cat urine

● Fox urine

Thermocouple

Electrode

E

Oscilloscope

Amplifier

Computer

Data Analysis

Analysis of electrophysiology data yields two distinct waveforms.

Trough

of action

potential

Crest of

action

potential

Unit A Unit B

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.

ksdksd

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

❖Possible Sources of Error

❖Future Implications

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of the American Association for Laboratory Animal Science. 2013: 124–129. Available from:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3624779/

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Jul 29] Available from: http://www.adaa.org/understanding-anxiety

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