Table 1.

Preclinical tasks assessing memory and attention.

Cognitive function	Task	Description	Reference
Memory	Radial arm maze	The radial arm maze consisted of an octagonal central chamber with eight attached arms. Each of the arms was baited with food, and the animal was expected to retrieve the reward (food) from each arm without revisiting a previously visited arm. Spatial working memory was measured by the number of baited arms entered prior to entering a previously visited arm. Chronic nicotine administration using subcutaneously implanted glass and silastic pellets (12 mg/kg salt) improved working memory 1 week after pellet implantation compared with saline controls. Subjects were female Sprague Dawley rats.	Levin et al., 1990
	Morris water maze task	In this task, animals were placed in the Morris water maze at different starting locations during multiple trials. The animals were expected to escape from drowning by locating a platform submerged under the water. The average distance traveled by the animal to locate the submerged platform from various start locations over multiple trials was used as a measure of working memory. The α7 agonist ABBF (1 mg/kg, per oral [p.o.]) improved working memory in aged rats in the Morris water maze task.	Boess et al., 2007
	Novel object recognition task	This task was performed over two trials separated by 24 h. In the first trial, the subject was allowed to explore two objects. The second trial, conducted 24 h after the first trial, consisted of presentation of an object from the previous trial and a novel object. The discrimination index, defined as the difference in time spent exploring the novel object minus the time spent exploring the familiar object divided by the total time spent exploring the two objects, was used to assess novel object recognition memory. The α7 agonist ABBF (0.3–1 mg/kg, p.o.) improved object recognition memory in mice.	Boess et al., 2007
	Social memory task	This task was performed over two trials separated by 24 h. On day 1, the adult rat being assessed was presented with a juvenile rat for a period of 2 min. Social investigation in the form of sniffing, grooming of body parts, anogenital sniffing, and close following was scored over the period of 2 min to build a composite social investigation score. On the following day (i.e., after 24 h), the adult rat was again presented with the same juvenile rat. A decreased social investigation score was indicative of social memory. The α7 agonist ABBF (0.3–1 mg/kg, p.o.) improved social recognition memory in rats.	Boess et al., 2007
	Delayed matching-to- sample task	This computerized task was designed to assess memory in nonhuman primates. The task involved presentation of a stimulus of a specific color on the computer screen. The subject was allowed to respond after a delay of up to120 s by pressing one of two illuminated keys. One of the two illuminated keys was of the same color as the stimulus presented on the screen. Selection of the key matching the color of the stimulus presented was considered a correct response. The percentage of correct responses was used as a measure of attention. The percentage of correct responses after the longest delay was significantly greater after nicotine (7.5 μg/kg, intramuscular injection) administration in aged monkeys compared with saline controls.	Buccafusco and Jackson, 1991
Attention	5-Choice serial reaction time task	The experimental subject was expected to monitor a light stimulus that was presented in one of the five equidistant located apertures. The animal signaled the detection of the light stimulus by nosepoking in the aperture where the light stimulus appeared. Correct responses were rewarded, and incorrect responses were punished with a timeout period. Accuracy, a measure of attention, was defined as the total number of correct responses divided by the total number of correct and incorrect responses. Chronic nicotine administration (9 mg/kg/day, salt) via minipumps improved accuracy 4–6 days after minipump implantation compared with saline controls in Wistar rats.	Semenova et al., 2007
	Sustained attention task	In this task, experimental animals were required to detect a light “signal” that varied in intensity. In a given trial, the signal may or may not have been presented prior to presentation of two levers in the chamber. The animal was expected to respond by responding on one of the two levers, and the correct lever was determined based on where the light signal was presented prior to the introduction of the levers in the chamber. Attention was assessed by determining the correct number of hits (i.e., responding on the correct lever when the signal was presented, defined as the total number of correct detections/total number of signal trials) or false alarms (i.e., animal incorrectly pressed the signal lever when no signal had been presented; number of false alarms/number of blank trials). Low doses of nicotine (0.0125, 0.025, and 0.05 mg/kg, salt; administered subcutaneously) dose-dependently increased the percent correct rejection in adult female Sprague Dawley rats. The same nicotine doses did not affect correct detections of the signal (i.e., percent hits).	Rezvani et al., 2002