sniffy

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Dec 6, 2023

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Running head: OPERANT CONDITIONING AND SNIFFY 1 Operant Conditioning and Sniffy Hunter College, City University of New York

OPERANT CONDITIONING AND SNIFFY 2 Abstract The Sniffy Pro is a program that provides a simulated rat (Sniffy) in a computer- generated operant chamber to study learning and conditioning. This virtual rat simulated performance of brain stimulation rewarding through operant conditioning. Sniffy was trained to lever press for reinforcement. Data was used from live rates achievement of brain stimulation reward threshold. Researchers questioned the threshold value for baseline and food deprivation rates. Results showed threshold values for baseline was significantly higher than values for food deprivation. 24-hour food deprivation lowers brain stimulation reward thresholds. Keywords : Sniffy, operant conditioning, brain stimulation, reward system Operant Conditioning Operant conditioning is a method of learning established by B.F. Skinner. This learning process occurs through rewards and punishments. Shaping is used to evoke a response as

OPERANT CONDITIONING AND SNIFFY 3 subjects make associations between behavior and consequence. B.F. Skinner conducted numerous experiments on animals to support his theory on operant conditioning. Since then many psychologists have performed the same experiments using rats and a Skinner box to validate and advance B.F. Skinner’s theory of operant conditioning. The lateral hypothalamus is essential for regulating metabolism and food intake. Ghrelin receptors are stomach produced hormones that stimulate ingestion behavior and increases motivated behavior to obtain palatable foods ( López-Ferreras et al., 2017). This area is crucial to food intake as associated lesions advance into aphagia and anorexia. Contrary to this the ventromedial hypothalamus is the nucleus of the hypothalamus involved in terminating hunger, this area is in due to the feeling of fullness. Research has shown that lesions in the ventromedial hypothalamus lead to overconsumptions and obesity. Rats used in experiments became overconsumed by freely available food and were less responsive to control when food was obtained by lever pressing ( Hawkins, Inoue, Mori, & Torii, 1994). These studies lead to the strong notion that the brain utilizes mechanisms that deal with behaviors. Such behaviors, like food intake, are turned on and off depending on whether a need is present or reduced. The study of the mechanisms of hunger closely relates to that of positive emotions. It was discovered that rats would lever press at exceptionally high response rates for the reward of brief electrical pulses (Olds & Milner, 1954). Later it was found that the lateral hypothalamus would functions as rewards sites just as it would evoke feeding behavior (Margules & Olds, 1962). This was then further supported as it was showed satiety reduced brain stimulation reward responding and deprivation enhanced brain stimulation reward responding through rats bearing electrode cannulas for electrical brain stimulation (Hoebel & Teitelbaum, 1961).

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OPERANT CONDITIONING AND SNIFFY 4 The research on reward mechanisms, food intake and hunger has led to many advancements in research and treatment in addiction and mental illness. This current experiment was conducted to further support the findings of how reward is mediated and the close relationship between the sites that control motivation. The researchers hypothesized that the virtual rat, sniffy, will learn to lever press for reinforcement through operant conditioning. The second hypothesis was 24-hour food deprivation lowers brain stimulation reward thresholds. Methods Subjects

OPERANT CONDITIONING AND SNIFFY 5 The experiment was performed using Operant Conditioning Training Demonstration : Sniffy the virtual rat. This was based on data from live Sprague-Dawley albino rats maintained on ad libitum food and water except for the food deprivation condition when only water was available. The animals were maintained under a 12:12 light dark schedule. The rats used in the brain stimulation reward experiments were surgically implanted with a single bipolar electrode aimed at the LH under IACUC approved surgical, anesthetic and post-operative procedures. Materials and Apparatus The virtual rat was held in an operant conditioning chamber, also known as a skinner box, that was just comfortably large enough to accommodate the rat being held inside of it. This chamber was sound proof and light proof to avoid distracting stimuli. On one wall there was a speaker to the right, a spherical object protruding from the wall to the left, and in the middle was a lever in which food was released from when pulled. Electrical brain stimulation equipment included pc computer, electrical constant current stimulator, oscilloscope, operant chamber from Coulbourn Instruments, and a printer. Threshold was determined using the Lewis and Phelps rate-independent brain stimulation computer program. Procedures The first experiment intended to train Sniffy to lever press through demonstration of operant conditioning. Each group of students in the class used the Sniffy Pro virtual rat program downloaded into the PC computers set up in the lab room. This program was used to experience standard operant training, Sniffy was magazine trained to the magazine mechanism that dispenses food reinforcement. This was done by clicking every time Sniffy got close to the mechanism in order to dispense food for her. Then she was trained to lever press for continuous

OPERANT CONDITIONING AND SNIFFY 6 reinforcement which was done by clicking to dispense food every time Sniffy mounted the wall by the food mechanism. Cumulative record and other performance for the session was recorded. For brain stimulation reward training and performance with food deprivation, each student was given data from rats trained to lever press for electrical brain stimulation. BSR training occurred in an operant chamber during three to five sessions. A swivel connector attached the rat to stimulation equipment. The rats were operant tested during the first two to four hours of the dark portion of their light-dark cycle (baseline testing, ad libitum food and water), and after 24 hours of food deprivation (water remained ad lib.) Reward threshold was calculated using psychophysical Method of Limits. The change in performance (the last Y changing to a N with descending current intensities or N to Y with ascending currents) was calculated with the respective to the preceding trial. So, a column that is descending from above threshold remained a Y value until N was found. For column in which were opposite subliminal levels (Ns until Y is found), the threshold is determined by the midpoint value between the last N and that of the Y value. These values are the midpoint of the values above and below the threshold. The values for each column were then averaged for each experimental condition (Baseline (control) and Food Deprivation). Thus, these values are the midpoint of the values above and below the threshold. Each value for the columns were then averaged across the descending and ascending values for each experimental condition (Baseline (control) and Food Deprivation). Results

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OPERANT CONDITIONING AND SNIFFY 7 As the researchers hypothesized, Sniffy learned how to lever press for reinforcement shown in figure 1.The mean threshold for baseline descending ( M = 54.58, SD = 5.19), ascending ( M = 45.00, SD = 5.64), and overall ( M = 46.70, SD = 5.03) was greater than food deprivation descending ( M = 38.33, SD = 10.70), ascending ( M = 36.67, SD = 8.36), and overall ( M = 37.51, SD = 9.26) A paired sample t-test was performed to compare the threshold data from baseline reward and food deprivation. There was a significant difference in the threshold scores for baseline ( M =53.96, SD = 5.03) and food deprivation ( M = 37.51, SD = 9.25) conditions; t (7) = 7.678, p = 0.00.

OPERANT CONDITIONING AND SNIFFY 8 Discussion The results of this study support the researchers’ initial hypotheses, through continuous schedule reinforcement sniffy learned to lever press on her own. The shaping process was tedious and required special attention in order to work as sniffy needed constant reassurance for her actions. Along with this threshold values decreased if the mouse was deprived of food for 24 hours. Deprivation threshold values amongst the eight mice were significantly less than baseline threshold values. Ghrelin controls a wide array of feeding behavior by acting directly on the LHA( López- Ferreras et al., 2017). Our study further supports this with the results of threshold values. Intra- LHA ghrelin increases actual dopamine neurotransmission which is shown to increase motivated response. As the mice are food deprived ghrelin hormone, also known as the hunger hormone, may help in the decrease of threshold and the increase of motivated response in subject. Opposite to this the ventromedial hypothalamus is the nucleus of the hypothalamus which regulates hunger and the feeling of fullness (Hawkins, Inoue, Mori, & Torii, 1994). A healthy ventromedial hypothalamus may explain why the results obtained by researchers included an increased baseline value. The mice that did not possess the feeling of hunger derived a decrease in motivation. The results agreed with discovery found describing brain sites that reinforce operant responding (Olds & Milner, 1954). 24-hour food deprivation produced increased threshold values aggregable to the acknowledged understanding that BSR responding reduces with engorgement and enhances with deprivation (Hoebel & Teitelbaum, 1961). Beyond limitation these results were significant because they were performed with the correct qualitative factors and contributions. Evidence contributed to the understanding that

OPERANT CONDITIONING AND SNIFFY 9 operant conditioning is affective in shaping an individual or subject. Food deprivation works alongside with hunger motivation further crediting the results researchers obtained. Limitations of this study includes the use of an online program for data. A virtual rat does lead to a healthy and complication free subject although it is based on a generated code which can lead to the data collected to be relatively similar to the next researcher who may use the same sniffy program. Another limitation in due to the second part of this experiment is the use of data that the researchers themselves did not conduct but rather was given to them by the course instructor. There is no way in knowing accurately if the mice used was completely healthy and if the method of data collection was precise. Future researchers should conduct experiments with live healthy mice if they have the means to do so. It would benefit to build off this study with live mice evaluating how they recall learned behavior and at what point they begin to forget said behavior, if they do. Also future researchers should conduct every aspect of the study themselves, collecting their own data and running their own experiments with their preferred methods rather than using data that was previously obtained by a different researcher.

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OPERANT CONDITIONING AND SNIFFY 10 Citation Hawkins, R. L., Inoue, M., Mori, M., & Torii, K. (1994). Lysine deficient diet and lysine replacement affect food directed operant behavior. Physiology & Behavior , 56 (5), 1061– 1068. https://doi-org.proxy.wexler.hunter.cuny.edu/10.1016/0031-9384(94)90344-1) Hoebel, B. G., & Teitelbaum, P. (1961). Regulation of feeding and self-stimulation by hypothalamic centers in the rat. PsycEXTRA Dataset . doi:10.1037/e666432011-068 Lewis, M., (2019). Important details in your paper for experiment 3 , week 10 Lecture. López-Ferreras, L., Richard, J. E., Anderberg, R. H., Nilsson, F. H., Olandersson, K., Kanoski, S. E., & Skibicka, K. P. (2017). Ghrelin’s control of food reward and body weight in the lateral hypothalamic area is sexually dimorphic. Physiology &Behavior , 176 ,40– 49. https://doiorg.proxy.wexler.hunter.cuny.edu/10.1016/j.physbeh.2017.02.011 Margules, D. L., & Olds, J. (1962). Identical "feeding" and "rewarding" systems in the lateral hypothalmus of rats. Science, 135, 374-375. http://dx.doi.org/10.1126/science.135.3501.374 Olds, J., & Milner, P. (1954). Positive reinforcement produced by electrical stimulation of septal area and other regions of rat brain. Journal of Comparative and Physiological Psychology, 47 (6), 419-427. http://dx.doi.org/10.1037/h0058775

OPERANT CONDITIONING AND SNIFFY 11 Figure 1. Sniffy CRF operant responding. Presented is an example of lever press operant behavior of sniffy for reward under a CRF schedule of reinforcement.

OPERANT CONDITIONING AND SNIFFY 12 Figure 2 . main results Baseline vs Food Deprivation.

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OPERANT CONDITIONING AND SNIFFY 13 Figure 3. Paired samples statistics & correlations (baseline vs. food deprivation)

OPERANT CONDITIONING AND SNIFFY 14 Figure 4. Independent samples t-test for baseline threshold values and 24-hour food deprivation threshold values.

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