All experiments were conducted in accordance with the National Institutes of Health guidelines and were approved by the Temple University Institutional Animal Use and Care Committee. This protocol was developed with adult (~60 days of age when starting the study) male and female Sprague-Dawley rats (Charles River).
1. Materials for Touchscreen SAT
2. Schedule Design for Touchscreen SAT
NOTE: The below protocol details how to set the parameters for the shaping and testing schedules for touchscreen SAT. All these schedules are also available upon request. Table 1 depicts the schedule parameters.
Training Stage | Max. Trials | Signal Duration (ms) | Special Conditions | Criteria | Median Days per Stage |
Nose Poke Shape | 120 | No events | Houselight on | 120 trials in 40 minutes | Males: 2, Females: 2 |
Training Schedule 1 | 162 | 500 | Houselight on; Correction trials; Response window lit at 50% during signal trials | > 70% Hits, > 70% CR, < 20% Omissions for 3 consecutive days | Males: 19, Females: 25 |
Training Schedule 2 | 162 | 500 | Houselight on | > 70% Hits, > 70% CR, < 20% Omissions for 3 consecutive days | Males: 13, Females: 21 |
SAT | 162 | 500, 50, 25 | Houselight on | > 70% Hits at 500 ms, > 70% CR, < 20% Omissions for 3 consecutive days | Males: 18, Females: 12 |
Table 1: Training Schedules and Average Acquisition Time for Each Schedule.
3. Procedure for Running Rats in Touchscreen SAT
4. Troubleshooting the Behavior
NOTE: It is normal for performance to drop when rats are transitioned to the next shaping phase (i.e., Nose Poke Shape to Training Schedule 1, Training Schedule 1 to Training Schedule 2, Training Schedule 2 to SAT). However, if performance does not improve over time or if a rat was performing well and then suddenly stops performing well, most often the issue is with food restriction.
For most attention studies, rats are trained to criteria on SAT and then manipulations to disrupt or improve attention are performed. Acquisition data is not typically presented, but we do so here to illustrate rates of acquisition in male and female Sprague-Dawley rats. To this end, we quantified the median number of days to reach criteria on SAT (starting on the Nose Poke Phase). Note that a few rats never made it to criteria (n = 5 males, and n = 1 female). The median days that it took male (n = 24) and female (n = 16) rats to reach criteria (including those who did not reach criteria in the allotted time) was 54.5 days and 62 days, respectively (Figure 1). There was no significant difference in acquisition time between the sexes [U = 165.5, Z = -0.75, p = .469]. It is notable that the variability in acquisition time appears greater in males [interquartile range (IQR) = 60.25] than females [IQR = 29.50].
Once rats acquired baseline, we evaluated the four typical performance measures in males (n = 19) and females (n = 15): percent hits, percent CRs, VI, and percent omissions. Based on the percentages of hits and correct rejections, males and females were similarly accurate on signaled [t(32) = .929, p = .360] and non-signaled trials [t(32) = .071, p = .394] (Figure 2a,b). As is typical with SAT, accuracy on non-signaled trials was better than accuracy on signaled trials [F(1, 32) = 129.99, p < .001], but this was not different between the sexes (i.e., no main effect of sex or interaction, [F's <1]). As noted, VI is calculated as an overall measure of attentional performance, and males and females had similar VIs [t(32) = .419, p = .678] (Figure 2c). Omissions were low, as expected with an optimal food restriction procedure, and comparable between the sexes [t(32) = 1.61, p = .118] (Figure 2d). To test performance across the session, we assessed changes across the three trial blocks and found no differences in hits [F(2, 64) = 2.75, p = .071] and correct rejections [F(2, 64) = 1.871, p = .162]. When comparing performance across trial blocks, there were no sex differences for hits and correct rejections [F's <1] or interactions between sex and trial block for hits [F(2, 64) = 1.427, p =.247] and correct rejections [F <1] (data not shown).
During SAT, the signals vary between 500 ms, 50 ms, and 25 ms and performance typically declines with the shorter signal durations10,17,18. We replicate that finding here, as accuracy declined with signal duration [F(2, 64) = 90.21, p < .001] (Figure 3a). Bonferroni post-hoc tests revealed a significant decline in percent hits from 500 ms to 50 ms (p < .001) and again from 50 ms to 25 ms (p = .017). Performance was comparable between males and females: there was no main effect of sex [F(1, 32) = 1.74, p = .267] or sex by signal duration interaction [F(2, 64) = 1.66, p = .198].
One way to increase attentional demands is by flashing the houselight during the second block of trials. We tested a subset of rats with this distractor (male n = 14, female n = 13). As expected, there was a main effect of session [F(2, 50) = 37.73, p < .001], such that performance declined during the second block of trials (post-hoc, block 1 vs. 2, p < .001), but recovered once the distractor ceased in block 3 (post-hoc, block 1 vs. 3, p = .862) (Figure 3b). There was a main effect of sex [F(1, 25) = 11.29, p = .003], such that females performed worse than males throughout the distractor session. Although there was no interaction between sex and performance for the trial blocks [F(2, 50) = .582, p < .563], planned comparisons between males and females at each trial block revealed that although males and females performed similarly in Block 1 (p = .144), females performed worse in Block 2 (p = .046) and Block 3 (p = .003), suggesting that the distractor is more disruptive in females and their recovery is worse.
Figure 1: Days to Criteria. The median number of days to reach criteria on the sustained attention task (SAT) was similar between males and females. However, male acquisition times are more variable, as they have a larger interquartile range (IQR) than females. Please click here to view a larger version of this figure.
Figure 2: SAT Performance Measures. (A, B) Male and female rats have similar accuracy on signal trials, as indicated with percent hits, and non-signal trials, as indicated with percent correct rejections (CRs). (C) The vigilance index (VI), an overall measure of attention, was also similar in both sexes. (D) Omissions were low and comparable between males and females. Data are presented as means ± standard error of the mean (SEM). Please click here to view a larger version of this figure.
Figure 3: SAT Performance Across Signal Durations and in the Presence of a Visual Distractor. (A) Signals during SAT vary in duration. As expected, percent hits (i.e., accuracy on signal trials) declines as signal durations get shorter and this effect was similar in both sexes. Asterisk indicates a significant difference from the 500 ms signal duration. (B) Performance on the Distractor SAT session is typically measured with the VI. As expected, the introduction of a distractor (i.e., flashing houselight) in Block 2 (illustrated with a black bar) decreased the VI in both males and females. Females had a lower VI throughout the session than males. Asterisk indicates a significant difference from Block 1 and Block 3 (p <0.05). Data are presented as means ± SEM. Please click here to view a larger version of this figure.
Bussey-Saksida Rat Touch Screen Chambers Easy-Install System | Lafayette Instrument | 80604-20 | Includes: Touch Screen, Chamber base with perforated floors, Large Feeder Reward Area (44.5mm wide x 92.5mm high), Speaker, Houselight, Tone Generator, SAC; Trapezoidal animal working area is 126mm wide at the Feeder, 240mm wide and 332 mm deep at the Screen, and 300 mm in height |
Sound Attenuation Cubicles (SAC) | Lafayette Instrument | 80604-20 | Attenuation to approximately 35dB; 38kg in weight; External dimensions: 600mm wide x 670mm tall x 352mm deep; Internal dimensions: 540mm wide x 610mm tall x 532mm deep |
Abet II Software for Touch Screens | Lafayette Instrument | 89505 | Version 2.19 |
Whisker Multimedia | Lafayette Instrument | 80698-1 | Required for Abet II Touch Operation |
Pellet Dispenser | Lafayette Instrument | 80209-45 | 45mg Interchangeable Pellet Size Wheel |
Camera | Lafayette Instrument | 80600-CAM | Filtered and focused for IR light |
Microsoft Windows | Microsoft | Windows 7-64 bit recommended | |
Controller PC-Touch Screen Chambers | Lafayette Instrument | 88530 | Dual Core Pentinum Processor; 2.5 GHz or greater; keyboard, mouse, and monitor; Installed PCI card, cable and expansion; Four RS232 ports; Four VGA ports |
Dustless Precision Pellets | BioServe | F0165 | 45 mg |
Black Acrylic Mask | Everything Plastic | Custom Product | Black polycarbonate with one matte finish side, 3.18 mm thick; Central circular opening, 28.58 mm diameter, 107.95 mm from the bottom, centered between the left and right side; Two square response areas, 28.57 mm x 28.57mm each positioned below and off center, one 85.725 mm from the left and one 85.725 mm from right side, and both 34.925 mm from the bottom. |
Utility Cart | Fisher Scientific | 11-954-754 | 30.75 in. x 18.38 in x 33 in |
Black towel | Large enough to cover cages for animal transport | ||
Headlights with red lights | Energizer | HDL33A2E | LED white and red light |
Sustained attention is the ability to monitor intermittent and unpredictable events over a prolonged period of time. This attentional process subserves other aspects of cognition and is disrupted in certain neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Thus, it is clinically important to identify mechanisms that impair and improve sustained attention. Such mechanisms are often first discovered using rodent models. Therefore, several behavior procedures for testing aspects of sustained attention have been developed for rodents. One, first described by McGaughy and Sarter (1995), called the sustained attention task (SAT), trains rats to distinguish between signal (i.e., brief light presentation) and non-signal trials. The signals are short and thus require careful attention to be perceived. Attentional demands can be increased further by introducing a distractor (e.g., flashing houselight). We have modified this task for touchscreen operant chambers, which are configured with a touchscreen on one wall that can present stimuli and record responses. Here we detail our protocol for SAT in touchscreen chambers. Additionally, we present standard measures of performance in male and female Sprague-Dawley rats. Comparable performance on this task in both sexes highlights its use for attention studies, especially as more researchers are including female rodents in their experimental design. Moreover, the easy implementation of SAT for the increasingly popular touchscreen chambers increases its utility.
Sustained attention is the ability to monitor intermittent and unpredictable events over a prolonged period of time. This attentional process subserves other aspects of cognition and is disrupted in certain neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Thus, it is clinically important to identify mechanisms that impair and improve sustained attention. Such mechanisms are often first discovered using rodent models. Therefore, several behavior procedures for testing aspects of sustained attention have been developed for rodents. One, first described by McGaughy and Sarter (1995), called the sustained attention task (SAT), trains rats to distinguish between signal (i.e., brief light presentation) and non-signal trials. The signals are short and thus require careful attention to be perceived. Attentional demands can be increased further by introducing a distractor (e.g., flashing houselight). We have modified this task for touchscreen operant chambers, which are configured with a touchscreen on one wall that can present stimuli and record responses. Here we detail our protocol for SAT in touchscreen chambers. Additionally, we present standard measures of performance in male and female Sprague-Dawley rats. Comparable performance on this task in both sexes highlights its use for attention studies, especially as more researchers are including female rodents in their experimental design. Moreover, the easy implementation of SAT for the increasingly popular touchscreen chambers increases its utility.
Sustained attention is the ability to monitor intermittent and unpredictable events over a prolonged period of time. This attentional process subserves other aspects of cognition and is disrupted in certain neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Thus, it is clinically important to identify mechanisms that impair and improve sustained attention. Such mechanisms are often first discovered using rodent models. Therefore, several behavior procedures for testing aspects of sustained attention have been developed for rodents. One, first described by McGaughy and Sarter (1995), called the sustained attention task (SAT), trains rats to distinguish between signal (i.e., brief light presentation) and non-signal trials. The signals are short and thus require careful attention to be perceived. Attentional demands can be increased further by introducing a distractor (e.g., flashing houselight). We have modified this task for touchscreen operant chambers, which are configured with a touchscreen on one wall that can present stimuli and record responses. Here we detail our protocol for SAT in touchscreen chambers. Additionally, we present standard measures of performance in male and female Sprague-Dawley rats. Comparable performance on this task in both sexes highlights its use for attention studies, especially as more researchers are including female rodents in their experimental design. Moreover, the easy implementation of SAT for the increasingly popular touchscreen chambers increases its utility.