This progressive ratio method can be used to examine the motivating properties associated with alcohol self-administration and capture the sources of variability of this behavior in humans. To assess risky patterns of alcohol consumption and relate them to risk factors for alcohol use disorder, this method can also test medications being developed to reduce drinking. To begin, connect the ethernet cable from the computer to the pump, and switch on the pump by pressing the gray power on button on the upper right side.
Then press the volume infused"button on the left side while ensuring that the numbers read zero. If the numbers do not read zero, press the clear button. Next, press the options edit"button, and then press the number four to select the computer control option.
Use the arrow buttons on the top row of the pump to select yes and press enter. Then look at the top of the pump screen to ensure that there is a computer control flashing on the screen. Connect the drink button that the participant uses to click for drinks into the USB portal closest to the participant, ensuring that the drink button is connected prior to opening the software or the software will not detect the button.
Insert the dongle, and select the drive to enter the password. Once the password has been accepted, open the drive titled Secu drive"to access the software. Double click the software icon, then click on file and select the option new session"Create a file name using desired participant number, then save the data to the desktop, not the dongle, as the software may overload the dongle and crash.
Select the PR experiment from the dropdown menu labeled select experiment"When the setup screen appears requesting further information on the participant, fill in the fields requesting participant identification number, select standard"as study type, then enter sex and age in the appropriately labeled fields. Enter height in centimeters and weight in kilogram in the required fields using the data collected earlier in the visit, then click on the submit"button. Move the window over the participant's monitor by clicking and dragging across the screen and enlarging to full screen so the participant can see it.
On the laptop, click on the start run"button at the top of the screen. Instruct the participant to press the drink"button as soon as the monitor prompts them to for their four individually standardized priming doses. After collecting the breath alcohol concentration at the 10 minutes mark, enter the breath alcohol concentration into the software by pressing control B and typing in the value to adjust the algorithm if needed.
Allow the participant to rest for 10 minutes. At the 25 minutes mark, inform the participant that the bar is open and include any further instructions required for the experiment. Click the data"tab on the software and select export.
The self-administration variables of peak breath alcohol concentration, total rewards earned, the total number of button presses, and the average rate of button pressing was compared for session one and two. Pearsons are ranged from 0.81 to 0.96 which shows a high test-retest reliability for all self-administration measures. The recent drinking history was closely associated with drinking behaviors in the lab including peak breath alcohol concentration, total ethanol, and system specific measures such as average rate and false button presses fraction.
Subjective responses were analyzed for low and high responders on measures of alcohol expectancies. Low responders reported overall negative expectancies of alcohol at baseline including expectations of cognitive and physical impairment. Subjective response measures during the priming phase revealed that high responders were willing to pay more for their next drink, whereas low responders felt more intoxicated.
During the open bar phase, the high responders reported higher peak scores for liking and wanting alcohol along with a higher peak urge for alcohol. They were willing to pay more for their next drink at the end of the open bar phase. The breath alcohol concentration trajectories revealed that at the 10 minute mark most participants achieved 30 milligrams per deciliter breath alcohol concentration.
Researchers have used this method to examine the effective mediator, such as ghrelin, on alcohol consumption, and examine the relationship between alcohol reward, craving, and seeking behavior.
