Spatial memory for food hidden by rats (Rattus norvegicus) on the radial maze: Studies of memory for where, what, and when.

Rats (Rattus norvegicus) were allowed to hide food items on an 8-arm radial maze by carrying the items from the center to boxes at the end of each arm. Retrieval tests given after rats had hidden 4 items showed that they selectively returned to the maze arms where food had been hidden (Experiments 1 and 2). When rats were allowed to hide pieces of cheese (preferred food) and pretzels (less preferred food) on different arms, they both hid and retrieved cheese before pretzels (Experiments 2-5). In Experiment 6, rats chose between arms where cheese and pretzels were hidden, with cheese degraded at one delay interval but not the other. Together, these experiments indicate memory for what and where but not when. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial memory in pigeons on the radial maze.

A series of 7 experiments with 10 pigeons showed, contrary to recent suggestions that pigeons show little or no spatial memory on the radial maze, highly accurate performance by Ss on an 8-arm radial maze. In Exp I, Ss were trained on successive phases that raised the number of alleys to be remembered from 1 to 4. In Exp II, Ss were allowed to search the maze for food with all 8 arms open. Measures of spatial memory showed that Ss performed at a level equivalent to that found with rats in previous research by A. B. Bond et al (see record 1982-25052-001). In Exp III, testing with massed trials revealed proactive interference. Ss were able to form reference memory for subsets of baited and unbaited alleys in Exp VI. In Exp VII, Ss learned about quantities of food associated with 4 different alleys and ordered their alley choices from the largest to the smallest reward. Contrary to the previous findings with rats, Ss in Exp IV showed forgetting over retention intervals of 0–360 sec between forced and free choices. It is concluded that spatial memory in pigeons generally shows the same properties as that in rats. (49 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Estrogen and estrogen-progesterone treatments counteract the effect of scopolamine on reinforced T-maze alternation in female rats.

Determined if steroid hormone treatments would attenuate the effect of the muscarinic receptor blocker scopolamine on a memory task. Ovariectomized rats were trained first to alternate for food reward between the arms of a T maze. Following training, Ss treated with scopolamine hydrobromide (0.2 mg/kg, ip) did not alternate correctly between the arms of the T maze and responded at chance levels. However, when estradiol benzoate (25 μg) was administered 72, 48, and 24 hrs before testing alone or in combination with progesterone (500 μg) administered 48 hrs before testing, Ss alternated successfully between the arms of the T maze following scopolamine administration. Results indicate that gonadal steroids can completely counteract the impairment of T maze performance induced by scopolamine in female rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of selective immunotoxic lesions of medial septal cholinergic cells on spatial working and reference memory.

The effect of injection into the medial septum of a toxin selective for cholinergic neurons, 192 IgG-saporin, was examined in rats trained to perform 2 versions of the radial 8-arm maze task. Rats were first trained to perform a task with varying delays (0, 1, 2 min) imposed between the 4th correct arm choice and access to all 8 arms. Lesioned rats made significantly more errors in the first 4 choices compared with controls and significantly more errors after delays; however, this effect was not delay dependent. Rats were then trained on a different version of this 8-arm maze task in which they learned to avoid 2 arms that were never baited. There was no treatment effect on acquisition of this task. These data are consistent with the hypothesis that the cholinergic projection to the hippocampus facilitates the acquisition of information into the system responsible for short-term memory for locations visited (spatial working memory) but is not involved in retention of this information. It also appears to play no role in either the acquisition or retention of place-nonreward associations (spatial reference memory). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short- and long-term components of working memory in the rat.

In Experiment 1 of this report, we examined the neuropharmacological nature of short-term working memory of rats trained to retrieve food from all arms of a 12-arm radial maze. Delay intervals of varying length were placed between Choices 6 and 7. Lanthanum (LaCl?) and glutamate (GLU) injected bilaterally into the hippocampus effectively impaired retention over short delay intervals, which suggests a possible role for calcium and/or potassium and for glutamate in working memory. However, another equally likely explanation for the amnesic effects of LaCl? and GLU is that these drugs impaired reference memory. To test more directly the hypothesis that LaCl?, GLU, or ANI might differentially affect working and reference memory, we tested the effects of these drugs on performance of rats trained to retrieve food from only 8 arms of the 12-arm maze in Experiment 2. The remaining 4 arms were never baited, in order to test reference memory function. We predicted that rats would make errors only in baited arms (i.e., errors of working memory). Instead, results of Experiment 2 showed that LaCl?, GLU, or ANI injection produced errors in unbaited arms even before a 120-min delay. If rats were injected with LaCl? or GLU, baited-arm errors were observed only after the delay period. No impairment of performance on baited arms were observed after injection of ANI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial guidance of choice behavior in the radial-arm maze.

In 6 experiments, the performance of male rats in a 12-arm radial maze was examined. The focus of study was the extent to which the spatial location of individual baited maze arms was determined before the rat was exposed to the extramaze visual cues corresponding to the arm, and thereby guided the rat toward the location of baited arms. Such spatial guidance of choice behavior implies a spatially organized cognitive representation of maze arms (i.e., a cognitive map). A higher level of spatial guidance was found when visual access to extramaze cues was restricted than when it was unrestricted. There was no evidence of a difference between the level of spatial guidance in the context of working memory performance and reference memory performance. Some evidence that intramaze cues contributed to microchoice guidance was found. However, spatial guidance, under at least some conditions, is best explained in terms of cognitive mapping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scopolamine affects response-to-change test involving 20-min retention interval after locomotor exploration in rats

The tendency to select the T-maze arm that has been changed in brightness between two successive trials (response-to-change) was investigated. Our previous findings indicated that scopolamine injections (1.0 mg/kg) impaired responding to change of brightness in a choice trial (trial II) following a 1-min retention interval, when in the first acquisition trial rats could only inspect the white-black T-maze arms through transparent partitions (the passive test). The drug was ineffective when rats were allowed locomotor exploration of the maze (the active test). The aim of the present experiment was to investigate the effect of the same dose of scopolamine on the active test involving a longer 20-min retention interval between the acquisition trial and the choice trial. The effect of cue salience also was examined by using grey-black arms. Rats injected with scopolamine (Scopo) 20 min before the acquisition trial performed in the white-black maze on the chance level, whereas saline-injected rats (Sal) showed significant preference for the changed arm. Decreasing the cue salience impaired response-to-change in Sal rats (50% of changed arm choices) but had no further effect on performance of Scopo rats, presumably because of a floor effect. The postacquisition injection had a somewhat stronger effect than the injections preceding acquisition, which most probably reflects the state dependency phenomenon. The deficient performance due to scopolamine treatment that appeared in the present study at a longer retention interval could be interpreted in terms of increased forgetting.     

Spatial memory in dogs (Canis familiaris) on a radial maze.

Working spatial memory in dogs (Canis familiaris) was tested in Experiments 1 and 2 on an 8-arm radial maze. When dogs chose freely among all 8 arms containing food in Experiment 1, they learned to enter all 8 arms with progressively fewer arm visits over trials. In Experiment 2, 2 groups of dogs were forced to visit 4 randomly chosen arms on the maze and then tested for memory of these arm visits using a win-shift rule for 1 group and a win-stay rule for the other group. Dogs performed better with the win-shift rule than with the win-stay rule. In Experiment 3, reference memory was investigated by using a 4-arm maze on which 0, 1, 3, and 6 pieces of food were consistently placed on different arms. Dogs learned to visit the arms with the larger amounts before the arms with the smaller amounts. Dogs’ memory capacity in these studies was found to be surprisingly low. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential involvement of the dorsal anterior cingulate and prelimbic–infralimbic areas of the rodent prefrontal cortex in spatial working memory.

[Correction Notice: An erratum for this article was reported in Vol 112(4) of Behavioral Neuroscience (see record 2008-09590-001). Figure 1 (page 295) and Figure 4 (page 299) were printed incorrectly. The corrected figure pages and corresponding captions are provided in the erratum.] The present study examined the effects of quinolinic acid lesions of the dorsal anterior cingulate and prelimbic–infralimbic cortices on spatial working memory and spatial discrimination using go/no-go procedures. All testing occurred in a 12-arm radial maze. In a working memory task, rats were allowed to enter 12 arms for a cereal reward. Three or 4 arms were presented for a 2nd time in a session, which did not result in a reward. In a spatial discrimination task, rats had successive access to 2 different arms. One arm always contained a reward, and the other never contained a reward. Prelimbic–infralimbic lesions impaired spatial working memory but only produced a transient spatial discrimination deficit. Dorsal anterior cingulate lesions did not induce a deficit in either task. These findings suggest that the prelimbic–infralimbic cortices, but not the anterior cingulate cortex, are important in spatial working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

List item memory in rats: Effects of delay and delay task.

The Serial Position Effect (SPE) was studied in rats using 2 manipulations analogous to those that have been shown to decrease the recency effect but leave the primary effect intact in human Ss. In Part 1, delays (5 sec to 60 sec) were imposed between exposure to a sequence of arms presented in 12-arm radial maze and a subsequent test phase. In Part 2, the effect of free access to food in a short (10-sec) delay was examined. The results from Parts 1 and 2 showed the primacy and recency effects were differentially sensitive to the delay and events within it. In particular the recency effect was found to be more sensitive to disruption from these sources. The present demonstration of a reduction in recency with procedures analgous to those used with humans extends the evidence, suggesting that the SPE obtained in rats and humans is a similar phenomenon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial memory deficits in a virtual radial arm maze in amnesic participants with hippocampal damage.

Extensive research with laboratory animals indicates that the hippocampus is crucial for the formation and use of spatial memory. Hippocampal lesions in rodents impair spatial memory on radial arm maze tasks. It is unknown whether amnesic patients with hippocampal damage would exhibit similar impairments on a virtual version of a radial arm maze. To evaluate the importance of the hippocampus in spatial learning and memory, we tested amnesic participants with hippocampal damage in a virtual radial arm maze environment. The virtual radial arm maze required participants to learn and remember 4 rewarded arms of 8 total arms. Spatial learning and memory were assessed using the participants' ability to use salient distal cues in the virtual room to remember the 4 rewarded arms. Amnesic participants' latencies were longer and distance traveled was greater to the rewarded arms compared with nonamnesic participants. Amnesic participants made more errors than nonamnesic participants by either entering nonrewarded arms or by revisiting previously entered arms. These data are analogous to previous animal research. Overall, the human hippocampus is necessary for spatial memory and navigation in a virtual radial arm maze task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial memory in pigeons on a four-arm radial maze.

Examined spatial memory in 6, 8-arm maze experienced pigeons, using a 4-arm radial maze. The maze arms were spaced at 90° intervals, extending radially from a central choice area. Ss were forced into 3 arms, then permitted 2 choices to enter the remaining arm. Five Ss chose accurately (90% correct) with delays of 5 min or less, their choices depended on extramaze cues, and the food in the target arm provided no essential cues. After an incorrect 1st choice, Ss' 2nd choices were more accurate than chance. Data suggest that, while spatial memory has many similar characteristics in rats and pigeons, pigeon spatial memory appears less durable. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential ontogeny of working memory and reference memory in the rat.

Examined the ability of 15-, 21-, and 27-day-old rats to perform 2 spatial working memory problems (delayed alternation and discrete-trials delayed alternation) and a reference memory problem (position habit) in a T-maze. In the delayed alternation problem, each S was presented with a series of free-choice trials and was rewarded for regularly alternating responses to the left and right arms of the T-maze. In the discrete-trials delayed alternation problem, each S was forced to one maze arm and rewarded (forced run) and was then placed back into the start box and given a choice of arms (choice run). The direction of forced runs followed an irregular, counterbalanced series, and Ss were rewarded for choosing the alternate maze arm on choice runs. In the position habit problem, Ss were rewarded for consistently choosing 1 of the 2 arms of the T-maze. At all ages, rat pups learned to perform the delayed alternation and position habit problems. Only 21- and 27-day-old rats were able to learn the discrete-trials delayed alternation problem. Results of these experiments show that reference memory capacity is present by at least 15 days of age in the rat and does not develop further at later ages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible memory processing by rats: Use of prospective and retrospective information in the radial maze.

Investigated the content of the memory used by rats in mediating retention intervals interpolated during performance in a 12-arm radial maze, using 10 Sprague-Dawley rats in Exps I and II and 21 Long-Evans rats in Exps III and IV. The delay occurred following either the 2nd, 4th, 6th, 8th, or 10th choice. A 15-min delay had the greatest disruptive effect when interpolated in the middle of the choice sequence and less of an effect when it occurred either earlier or later. This pattern was obtained when either a free- or forced-choice procedure was used prior to the delay and regardless of whether postdelay testing consisted of completion of the maze or 2-alternative forced-choice tests. Assuming that the disruptive effect of a delay is a function of memory load, this implies that Ss used information about previously visited arms (retrospective memory) following an earlier interpolated delay but information about anticipated choices (prospective memory) following a delay interpolated late in the choice sequence. There appeared to be a recency effect only in the early and middle delay conditions. Data provide converging evidence for the dual-code hypothesis. No evidence for prospective memory was obtained following a 60-min delay. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Differential involvement of the dorsal anterior cingulate and prelimbic-infralimbic areas of the rodent prefrontal cortex in spatial working memory": Correction to Ragozzino et al. (1998).

Reports an error in "Differential involvement of the dorsal anterior cingulate and prelimbic-infralimbic areas of the rodent prefrontal cortex in spatial working memory" by Michael E. Ragozzino, Spencer Adams and Raymond P. Kesner (Behavioral Neuroscience, 1998[Apr], Vol 112[2], 293-303). Figure 1 (page 295) and Figure 4 (page 299) were printed incorrectly. The corrected figure pages and corresponding captions are provided in the erratum. (The following abstract of the original article appeared in record 1998-01023-003.) The present study examined the effects of quinolinic acid lesions of the dorsal anterior cingulate and prelimbic-infralimbic cortices on spatial working memory and spatial discrimination using go/no-go procedures. All testing occurred in a 12-arm radial maze. In a working memory task, rats were allowed to enter 12 arms for a cereal reward. Three or 4 arms were presented for a 2nd time in a session, which did not result in a reward. In a spatial discrimination task, rats had successive access to 2 different arms. One arm always contained a reward, and the other never contained a reward. Prelimbic-infralimbic lesions impaired spatial working memory but only produced a transient spatial discrimination deficit. Dorsal anterior cingulate lesions did not induce a deficit in either task. These findings suggest that the prelimbic-infralimbic cortices, but not the anterior cingulate cortex, are important in spatial working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesions of basolateral and central amygdala differentiate conditioned cue preference learning with and without unreinforced preexposure.

In the separated arms conditioned cue preference (CCP) task rats are trained by confining them in one arm of an eight-arm radial maze with food and in another arm on the opposite side of the maze with no food on alternate days. After two such trials, rats prefer the food-paired arm when allowed to move freely between the two arms, neither of which contains food. However, if the rats are preexposed to the maze by exploring it without food before training, no preference is observed and at least 4 training trials are required to produce a CCP, suggesting that unreinforced preexposure to the maze latently inhibits acquisition. If this interpretation is correct, preexposure should reduce the size of the preference acquired with both 2 and 4 training trials. In Experiment 1, this prediction was replicated for 2 training trials; however, with 4 training trials, eliminating preexposure also eliminated the CCP. A previous finding that basolateral amygdala lesions impair the CCP with preexposure and 4 training trials was replicated in Experiment 2, but similar lesions had no effect on the CCP in nonpreexposed rats given 2 training trials. In contrast, lesions of the central nucleus impaired the 2 training trial CCP but had no effect on the 4 training trial CCP. This double dissociation suggests that the BLA-mediated 4 training trial CCP may be due to learning about the reward features of the maze space, while the central-nucleus-mediated 2 training trial CCP may be due to a conditioned approach response. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Deficits of spatial learning and working memory in spontaneously hypertensive rats

It is possible that behavioral dysfunction, including cognitive, perceptual and psychomotor impairments in hypertensive subjects, can be the result of the high blood pressure. The aim of this study was to evaluate the performance of the spontaneously hypertensive rats (SHR) in the acquisition and execution of tasks in an 8-arm radial maze. Male Wistar normotensive rats (CON, n = 11) and SHR (n = 12), 3 months old, were first submitted to a series of training sessions to enter each of the 8 arms once in a given session (task acquisition), and errors (revisiting an arm in the same session) were computed. Errors before and after two delay intervals (5 s and 1 h, introduced between the fourth and fifth arm choice) were measured. These delayed tests allowed us to evaluate the working memory in different terms. It was observed that the SHR group made slightly more errors during the acquisition sessions and in the execution of the post-delay of 5-s interval tests, and significantly in the execution of the post-delay of 1-h interval tests compared to the CON. These results show that the SHR has a deficiency in the performance of the radial maze, suggestive of impairment of learning and working memory, mainly for a long-term memory, corroborating the hypothesis about the possible behavioral consequences of hypertension.     

Parasympathetic neurons in the cranial medial ventricular fat pad on the dog heart selectively decrease ventricular contractility

The present study examined the performance of rats with neurotoxic lesions centred in the thalamic nucleus medialis dorsalis on standard and modified versions of the eight arm radial maze test. In Experiment 1, the thalamic lesions produced a borderline deficit in acquisition of the standard task, but subsequently had no effect when a delay was interposed after the first four arms had been entered. The same lesions had no effect on T-maze alternation, but they did impair radial-arm maze performance when intramaze and extramaze cues were set against each other. In Experiment 2, lesions of the dorsomedial thalamus impaired acquisition of the standard radial-arm maze task, but combining the results from Experiments 1 and 2 showed that this acquisition deficit was confined to those animals in which bilateral damage extended into the adjacent anterior thalamic nuclei. In addition, lesions of the dorsomedial thalamus disrupted radial-arm maze performance when the task was modified to compare working memory and reference memory and increased activity and exploration. These changes were not associated with anterior thalamic damage. Finally, the thalamic lesions did not affect performance on a test of spontaneous object recognition. It is concluded that lesions of medialis dorsalis do not disrupt spatial memory but do affect other processes that can interact with task performance. These include a failure of extramaze cues to overshadow intramaze cues, a change in activity and exploration levels and deficits in with-holding spatial responses.     

Rats acquire spatial learning sets.

Examined the development of a spatial learning set in 6 male Sprague-Dawley rats and some of the variables influencing the retention of individual problems. The apparatus was a plus maze. At the beginning of each test, the S was put on 2 arms, each in a different place. Food was present in one of the arms, but not in the other. The S was then given a choice between these 2 places; the correct response was to return to the place that previously contained food (win–stay, lose–shift, response–reinforcement contingency). 50 different 2-choice spatial discriminations were given, each with the maze in a different location. Results indicate that at the end of testing, the mean percentage of correct responding for the 1st choice between the 2 places was 83%. Control procedures showed that the discriminative stimuli were distal, extramaze spatial stimuli. Variations of the procedure examined the influence of proactive interference and temporal delay on the memory for each discrimination. It is suggested that rats can develop a spatial learning set and provide new information about the characteristics of the memory underlying learning sets. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial learning by rats across visually disconnected environments

Two spatial tasks were designed to test specific properties of spatial representation in rats. In the first task, rats were trained to locate an escape hole at a fixed position in a visually homogeneous arena. This arena was connected with a periphery where a full view of the room environment existed. Therefore, rats were dependent on their memory trace of the previous position in the periphery to discriminate a position within the central region. Under these experimental conditions, the test animals showed a significant discrimination of the training position without a specific local view. In the second task, rats were trained in a radial maze consisting of tunnels that were transparent at their distal ends only. Because the central part of the maze was non-transparent, rats had to plan and execute appropriate trajectories without specific visual feedback from the environment. This situation was intended to encourage the reliance on prospective memory of the non-visited arms in selecting the following move. Our results show that acquisition performance was only slightly decreased compared to that shown in a completely transparent maze and considerably higher than in a translucent maze or in darkness. These two series of experiments indicate (1) that rats can learn about the relative position of different places with no common visual panorama, and (2) that they are able to plan and execute a sequence of visits to several places without direct visual feed-back about their relative position.