Experiment "Social Transmission"

?Rats are neophobic (i.e. afraid of new experiences) and show a reluctance to eat new things. Often, rats will only sample a small amount of a novel food, and return later if the first sampling did not make them sick. This is believed to be an adaptive behavior in the wild where new foods may be poisonous.

However, rats may eat a novel food they encounter if they have other reasons to expect that it is not dangerous to ingest. For example, in the social transmission of food preference paradigm (STFP) an "observer rat" can learn about the palatability of a food by exposure to a "demonstrator rat" that has previously eaten the food.

It has been shown that the smell of the food on the demonstrator (particularly its breath) signals to the observer rat that the food is safe to eat. In the following experiment we will investigate this effect by testing whether the observer rat prefers the demonstrated food.

Procedure

There are three phases of this experiment: a demonstration phase, an interaction phase and a test phase. Each one is described below. Demonstrator rats will be at 85% of their free feeding weight. Observer rats will be provided food and water ad libitum.

Phase 1: DEMONSTRATION PHASE

Demonstrator rats are exposed to assigned flavor for 10 minutes. Demonstrator rats will be placed in the open field apparatus with a small, plastic dish of 25 flavored pellets placed in the open field (dish in the same location as in the observer phase).

After 10 minutes, or after all of the pellets are eaten, record how many pellets the demonstrator rat has eaten. Remove the demonstrator and dish of pellets from the open field. If less than 5 pellets were eaten, the flavored powder from the pellets should be wiped around the demonstrator's snout prior to the interaction phase. Wipe down the apparatus.

Demonstrator??Flavor of Food Pellet

Rat #25? ?CINNAMON??

?Rat #26?? ? COCOA??? ?

?Rat #27?? ?CINNAMON

?Rat #28?? ?COCOA?? ?

Phase 2: INTERACTION PHASE

Both demonstrator and observer rats are placed in the open field apparatus together for 30 minutes. Begin by placing the rats in opposite corners, with each one facing the walls.

Record the following 3 types of interactions:

1. Number of anterior- anterior (head to head) interactions performed by the observer to the demonstrator.

2. Number of anterior-posterior (head to body or hindlimb section) interactions performed by the observer to the demonstrator.

3. Amount of time (in minutes) the observer spends in the same quadrant of the open field as the demonstrator.

After 30 minutes, return both the demonstrator (mark on tail) and observer to their home cages. Wipe down the open field. Enter data into Excel spreadsheet.

Data Collection Sheet

Demonstrator Rat ________

Demonstrator Flavor ___________

Observer Rat ________

Demonstrator Phase:

?Number of pellets eaten ________

?Interaction Phase: (record observer performed actions only)

?Number of anterior-anterior (head to head) interactions _________

?Number of anterior-posterior (head to body) interactions _________

Amount of time spent in same quadrant _________

Phase 3: OBSERVER PHASE

Observer rat is exposed to two flavors, cinnamon and cocoa, to determine its food preference. A small dish of 40 cinnamon pellets is placed in the center of one quadrant of the open field, and a small dish of 40 cocoa pellets is placed in the center of the opposite quadrant (see Figure 1).

This phase will include four 5-minute trials, with 3-minute intertrial intervals (ITI). Begin each trial by placing rat in the center of the testing apparatus. Record the amount of time the observer rat spends in the demonstrator's flavor quadrant. Also, record the amount of time the observer rat spends in the other flavor's quadrant.

During each 3-min ITI, record the number of pellets eaten during the trial, refill the dishes to 40 pellets, and then return the dishes to the same location in the apparatus. Food preference will be determined by the number of pellets consumed and the amount of time spent in each flavor's quadrant. After the 4 trials are complete, return the observer to its home cage.

Wipe down the open field. Enter the data into the Excel spreadsheet.

Room lights should be dim (only one of the switches on). Make sure to remain as quiet as possible, as any noise or distracting movement will disturb your experiment. IMPORTANT: Avoid cross-contamination of the cinnamon and cocoa pellets by having a person handle only one flavor.

Some questions to keep in mind:

Do observer rats show an increased preference for whichever food was demonstrated to them?

If so, do the types of interaction and amount of contact time between demonstrator and observer rats during the demonstration phase correlate to the social transmission of food preference?

What is the evidence that the observer rat learned something? What would you expect if they didn't learn anything?

If rats normally have a preference for one flavor before the demonstration, how could this affect the results?

If the observer rat were to become ill after ingesting its preferred food during the test phase, what do you think would happen to its food preference if you tested again the next day?

Resources :

Article 1 : Social Interaction with an Intoxicated Sibling Can Result in Increased Intake of Ethanol by Periadolescent Rats BY Pamela S. Hunt,Jennifer L. Holloway and Elka M. Scordalakes.

Article 2 : A Failure to Find Socially Mediated Taste Aversion Learning in Norway Rats (R. norvegicus) By Bennett G. Galef, Jr., Stephen W. Wigmore, and Deborah J. Kennett.

Article 3 : TRANSFER OF INFORMATION CONCERNING DISTANT FOODS: A LABORATORY INVESTIGATION OF THE 'INFORMATION-CENTRE' HYPOTHESIS By BY BENNEIT G. GALEF, JR & STEPHEN W. WIGMORE

Attachment:- Results.rar