Hotel
Description of Dr. Smith's 8 cage hotel
Citation: Smith, JC. Microstructure of the rat's intake of food, sucrose and saccharin in 24-hour tests. Neuroscience and Biobehavioral Reviews 24 (2000)199-212. PMID 10714383
Old stainless steel wire-bottom cages (dimensions: ?? X ?? X ?? cm) vs. Newer polycarbonate solid-bottom cages
Rats were housed in standard polycarbonate wire-top cages measuring 27 x 48 x 20 cm (more exactly 10.5" x 19" x 8") 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 (?? x ?? x ?? cm) 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].
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))
Hotel File Formats
Raw File Format
6 byte header with 3 numbers. Each number is 16 bit integer, in lo-hi byte order
file_buffer [0],[1] -- # of pts in the file -- maximum of 13800 (0x35E8) file_buffer [2],[3] -- pt of lights OFF file_buffer [4],[5] -- pt of lights ON
data pts represent 6-second bins. Each data pt is 1 byte. There are 3 channels of data pts.
For the food cup channel, the data pt a byte ranging from 0 to 63 (x3F), should be scaled to number of seconds the infrared beam was broken per bin (range: 0-6): byte value / 63 * 6 = number of seconds.
For the 2 bottle channels, the data pt contains the number of beam breaks (licks) per bin (range: 0 - ~40); the byte value does not require scaling (i.e. byte value = number of licks/bin).
The arrays of data pts for each data channel appear consecutively in the data file
file_buffer[6] to file_buffer[num_of_pts+5] = food cup data pts file_buffer[6 + num_of_pts] to file_buffer[(2*num_of_pts)+5] = left bottle data pts file_buffer[6 + (2*num_of_pts)] to file_buffer[(3*num_of_pts)+5] = right bottle data pts
CSV Files produced by LTAW
header line, followed by one line for each bout (note commas at end of line...)
name of bout file: "B<channel0-1>YYMMDD.CSV" <filename>,<nothing?>,<channel0-2>,<lightsoff_pt>,<totalcounts>,<lightson_pt>,<pts_per_bin?>,<startpt>,<endpt>,<validpt>,<minbin>,<IBIpts>, <zeroindexed bout num>,<startpt>,<endpt>,<counts>,
example:
CA15SET.C01,,0,7037,4181,11384,1,0,13797,3,50,30, 0,2222,2242,109, 1,3194,3269,392, 2,4201,4325,526, 3,4441,4686,977, 4,5628,5719,479, 5,6114,6251,678, 6,7139,7245,585, 7,7400,7492,459, 8,8204,8330,543, 9,9440,9685,1102, 10,10159,10275,607, 11,10782,10886,541
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)