Hotel
Description of Dr. Smith's 8 cage hotel
Rats were housed in standard polycarbonate wire-top cages measuring ?? X ?? X ?? modified with holes cut in the front and in the rear of the cage to accommodate one feeding compartment and two drinking ports. A stainless steel nest box was placed inside the cage. At the front of the cage a stainless steel food compartment held a 4 oz glass food jar. When a rat entered the feeding compartment, its head broke an infrared beam located above the food jar so that every second during the 23-h period the rat had its head inside the compartment was recorded. Thus, time in the food compartment during a feeding episode, not amount of food intake, was measured. However, under baseline conditions, it has been shown that there is a high correlation between direct measures of food consumption (using load beams or videography) and the duration of a feeding bout [JODI and MEGAN PAPER].
Need to find dimensions and papers to cite -- TAH 2-4-09
A two-bottle stainless steel holder was located opposite the food compartment. In the present experiment, only one bottle was used; it was placed on the left side for the duration of the experiment. The sipper tube on the bottle was recessed behind a slot, allowing contact circuits to record each lick that the rat made during a 23-h period.
A computer recorded time spent in the food compartment and number of licks with 6-s resolution, meaning that after every 6-s bin, the number of seconds that the rat was in the food compartment and the number of licks on the sipper tube were recorded. This resulted in 13,800 6-s bins for every 23-h testing period during which the data were recorded. The computer was always started by 1000 h. A photo detector allowed the computer to record the time when the room lights went off and on during the 23-h period.
Variables collected by Dr. Smith's hotel
Any differences found in food and water intake during the experiment could be due to a change in a variety of factors: (1) the number of ingestive episodes (bouts), (2) the duration of these bouts, (3) the efficiency of feeding or drinking within the bouts, or (4) intake occurring outside of a bout (sampling). Feeding and drinking bouts were defined as follows:
For feeding, a bout started when a rat entered the food compartment for 3 sec. The bout had to include at least 30 s with the rat within the food compartment (i.e. breaking the infrared beam) in order to be included as a valid bout. The bout ended when the rat left and did not re-enter the food compartment again for 50 6-s bins (5 min).
For drinking, a bout started when a rat made 3 licks. A drinking bout had to contain at least 30 licks to be included as a valid bout. The bout ended when the rat did not lick for 50 6-s bins (5 min).
Using the daily food and fluid intake and the above bout criteria, the following dependent variables were measured or calculated for each day:
- body weight, measured in grams
- intake, measured in grams
- number of daytime bouts
- number of nighttime bouts
- total number of bouts
- total licks per bout
- total number of licks included in all bouts
- total number of licks NOT included in bouts (sampling licks)
- total bout length, measured in number of 6-sec bins (multiple * 6 to get seconds)
- volume per lick, measured in microliters
- efficiency, in grams / minute (intake / ((total number of bouts)X(total bout duration))
LTAW Variables
| LIX | licks |
| BLIX | licks within bouts |
| BT | bout number |
| BTL | bout length (# of 6-sec bins) |
| LBT | Licks per bout |
| IBI | interbout interval |
LTAW Bout Criteria
Minimum Size of a Valid Bin
units: counts per 6-second bin (licks/6seconds) or (number of seconds in food-cup)
if a bin has fewer than this number of licks or beam-break-seconds, then the data in this bin is ignored and not included in analysis
Example: if minimum size is set to 3, then the sequence of bins
0,0,1,0,0,2,0, 0,5,0,0,3,0,0,1,0,0,6
is filtered for purposes of analyses to become the sequence:
0,0,0,0,0,0,0, 0,5,0,0,3,0,0,0,0,0,6
Minimum number of invalid bins between bouts
Units: number of 6-second bins
The minimum interbout interval; typically is 5 minutes = 50 x 6-sec bins
Example:
0,0,0,5,6,6,5,6,5,4,3,6,0,0,0,0, …[40 empty bins] ….0,6,5,6,5,4,5,0, …. [60 empty bins]….0,6,5,6,
^ ^ ^ ^
start same end start
of bout bout of bout of next bout
Minimum size of a valid bout:
Units: number of counts within the bout (licks or seconds in food-cup)
So if set to 30, then
a sequence of bins totalling 30 licks (or 30 seconds in the food cup) is a potential bout with on
Derived measures
Bout length in seconds = TOTBTL * 6
(sometimes "bout length" is referred to as "bout duration" or as "bout size" -- the use of size is ambiguous as to time or quantity e.g. of licks, so I prefer not to use size.
Bout Rate in licks/ second = (total licks per bout) / (total bout length in bins * 6)