Entire Maze Research Articles

Assessing rapid spatial working memory in community-living older adults in a virtual adaptation of the rodent water maze paradigm

Aging often leads to a decline in various cognitive domains, potentially contributing to spatial navigation challenges among older individuals. While the Morris water maze is a common tool in rodents research for evaluating allocentric spatial memory function, its translation to studying aging in humans, particularly its association with hippocampal dysfunction, has predominantly focused on spatial reference memory assessments. This study expanded the adaptation of the Morris water maze for older adults to assess flexible, rapid, one-trial working memory. This adaptation involved a spatial search task guided by allocentric cues within a 3-D virtual reality (VR) environment. The sensitivity of this approach to aging was examined in 146 community-living adults from three Chinese cities, categorized into three age groups. Significant performance deficits were observed in participants over 60 years old compared to younger adults aged between 18 and 43. However, interpreting these findings was complicated by factors such as psychomotor slowness and potential variations in task engagement, except during the probe tests. Notably, the transition from the 60 s to the 70 s was not associated with a substantial deterioration of performance. A distinction only emerged when the pattern of spatial search over the entire maze was examined in the probe tests when the target location was never revealed. The VR task's sensitivity to overall cognitive function in older adults was reinforced by the correlation between Montreal Cognitive Assessment (MoCA) scores and probe test performance, demonstrating up to 17 % shared variance beyond that predicted by chronological age alone. In conclusion, while implementing a VR-based adaptation of rodent water maze paradigms in older adults was feasible, our experience highlighted specific interpretative challenges that must be addressed before such a test can effectively supplement traditional cognitive assessment tools in evaluating age-related cognitive decline.

Egocentrically-stable discriminative stimulus-based spatial navigation in mice: implementation and comparison with allocentric cues

Animals are capable of using visual cues to find the correct route during navigation. These visual cues, which contain spatial information on the direction towards the goal point, are perceived either allocentrically or egocentrically. In this study, we examined how navigating with these two types of visual cues affects the learning processes of rodents. To present egocentrically-stable spatial cues, we devised a head-mounted device that provided discriminative orientation cues that indicated the correct choice at a fork within a double Y-maze. For allocentrically-stable spatial cues, LEDs serving as external route-mark cues were attached to the walls of the double Y-maze and illuminated to indicate the correct pathway. To rule out the possibility of the mice using extra-maze cues, we rotated the entire maze and used different start and goal sites for every trial. Our results revealed that mice using egocentric cues and external route-mark cues both showed a sigmoidal learning process for spatial navigation and that external route mark-based learning, surprisingly, learned faster than egocentric stimulus-based learning in egocentric space.

Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes.

This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scatteredphotons at the maze entrance. The dose of the backscatteredphotons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscatteredphotons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.

A computational model for exploratory activity of rats with different anxiety levels in elevated plus-maze.

The elevated plus-maze is an apparatus widely used to study the level of anxiety in rodents. The maze is plus-shaped, with two enclosed arms and two open arms, and elevated 50cm from the floor. During a test, which usually lasts for 5min, the animal is initially put at the center and is free to move and explore the entire maze. The level of anxiety is measured by variables such as the percentage of time spent and the number of entries in the enclosed arms. High percentage of time spent at and number of entries in the enclosed arms indicate anxiety. Here we propose a computational model of rat behavior in the elevated plus-maze based on an artificial neural network trained by a genetic algorithm. The fitness function of the genetic algorithm is composed of reward (positive) and punishment (negative) terms, which are incremented as the computational agent (virtual rat) moves in the maze. The punishment term is modulated by a parameter that simulates the effects of different drugs. Unlike other computational models, the virtual rat is built independently of prior known experimental data. The exploratory behaviors generated by the model for different simulated pharmacological conditions are in good agreement with data from real rats.

Spatial learning in a T-maze by the crayfish Orconectes rusticus.

The T-maze has commonly been used to investigate the mechanisms underlying spatial learning in vertebrates and has yielded much information about how animals use response and place cues to orient toward a goal. We designed a T-maze to study the spatial learning abilities of crayfish (Orconectes rusticus), using tactile stimuli as a place cue and escape from warm water for reinforcement. An initial experiment found that most animals did not display a side-turning bias when first placed in the maze, and hence animals were randomly assigned to escape from the left or the right arm, one of which contained a smooth floor and the other a rough floor. We found that, over repeated trials, the latency to escape and the number of turns made prior to escaping significantly decreased indicating that crayfish learned to escape from the maze more rapidly and efficiently. Learning occurred over the course of six trials on a single day, and over 5 days of testing, providing evidence for spatial memory lasting 24 hr. In probe trials, in which experienced animals started the maze in an arm opposite to that used during training trials, crayfish did not display a preference for either response-based learning or place-based learning. Instead they engaged in renewed exploration of the entire maze. These findings suggest that, in addition to remembering the location of the exit, crayfish also remembered the overall configuration of the maze.

Induction of habits in rats by a forced-choice procedure in T-maze and the effect of pre-test free exploration

A forced-choice procedure in T-maze designed for the induction of habits was used to induce strong habits in rats. The response choices of rats in 20 free-choice trials were compared after the rats had been subjected to 1 or 200 forced-choice trials to one side of the T-maze. After 200 forced-choice trials the rats showed a significant (p<.001) propensity for the habitual arm of the maze in the subsequent free-choice trials. The habit was at least as pronounced when analysed over the last 10 free-choice trials as when it was analysed over the first 10 free-choice trials. When the rats were given the opportunity to explore the entire maze immediately before the free-choice challenge after 200 forced-choice trials, this resulted in a large variation in the choice pattern of the individual rats, and a subgroup of rats choose the newly opened maze arm in 95-100% of the 20 free-choice trials.

The role of hippocampal glutamate receptor-A-dependent synaptic plasticity in conditional learning: the importance of spatiotemporal discontiguity.

Gene-targeted mice lacking the AMPA receptor subunit glutamate receptor-A (GluR-A or GluR1) and mice with cytotoxic hippocampal lesions were compared with wild-type and sham-operated controls, respectively, on a conditional learning task using an elevated T-maze. Floor inserts (white perspex vs wire mesh) provided a conditional cue indicating in which goal arm a food reward was to be found. The relationship between the floor insert and the rewarded goal arm was constant throughout the experiment. Both lesioned and knock-out mice were able to acquire the task if the floor inserts extended throughout the entire maze, including the start arm and both goal arms. In contrast, both lesioned and knock-out mice were unable to acquire the task if the floor inserts were only present in the start arm of the maze. The absence of the conditional cue (the floor insert) at the time when the place-reward association was experienced thus critically determined whether or not the mice were impaired. We suggest that hippocampal GluR-A-dependent synaptic plasticity contributes to a memory system in rodents for encoding both the spatial and temporal contexts (the where and the when) associated with a particular event.

Validation of a left atrial lesion pattern for intraoperative ablation of atrial fibrillation

Background. Evidence that atrial fibrillation may begin in early stages from triggers or reentry circuits primarily in the left atrium suggests that the entire Maze 3 lesion pattern may be unnecessary. In the present study we describe a new left atrial lesion pattern for intraoperative linear ablation of chronic atrial fibrillation.Methods. Endocardial radiofrequency ablation was performed on 12 dogs with chronic atrial fibrillation. Lesions to isolate pulmonary veins in pairs, the left atrial appendage, and connecting lesions between these structures were administered in a randomized approach.Results. Twelve dogs were in chronic atrial fibrillation for 31 ± 21 days before ablation. Atrial fibrillation was successfully ablated and rendered noninducible in all 12 dogs. All treatment failures observed with less than the full lesion pattern became a success when the remaining lesions were given.Conclusions. Atrial fibrillation ablation using this left atrial lesion pattern is highly successful in this model. This approach may have significant utility as a concomitant procedure for patients with atrial fibrillation undergoing mitral valve procedures.

Postdrug retention of diazepam’s effects on habituation to a novel environment in an animal model of anxiety

In two experiments it was demonstrated that diazepam can have habituation-facilitating effects that will be retained beyond the termination of drug action. Rats given multiple exposures to a novel plus maze 30 min after an injection of diazepam (2.0 mg/kg) on each occasion explored the “open” (exposed) arms of the maze more than animals injected with saline or yohimbine hydrochloride did. All groups exhibited equivalent rates of increase in this activity over repeated trials in the maze—behavior that was interpreted to reflect habituation to the environment and, in particular, habituation to the somewhat aversive open arms. When shifted to saline injections in later trials, the animals with diazepam experience retained their relatively higher level of open-arm exploration for as long as 56 days after their last diazepam injection. In a third experiment, animals were confined to the open arms of the maze on five occasions following either a diazepam or a saline injection and were then tested drug-free in the complete maze on subsequent trials. Here the diazepam-experienced animals did not differ from the saline controls. The forced exposure to the open arms, although unequally stressful to the diazepam- and saline-injected animals as indicated by their different fecal bolus counts, yielded comparable, high levels of open-arm exploration in both groups of subjects once they were permitted access to the entire maze.

A design overview of a Micromouse: University of the Pacific electronics team designs a jewel of a mouse

The second annual IEEE Micromouse Competition, which took place at California State University at Sacramento in April 1985, included an entry built by the University of the Pacific (UOP) Micromouse Team, of which I was a member. IEEE rules specify a “Micromouse” to be a self-contained robot with a maximum superstructure length and width of ten inches. Each mouse is given three runs through the maze, which has outside dimensions of eight feet by eight feet (although the entire maze has not been used in a Region Six competition) with six-and-a-half inches of spacing between walls (Fig. 1). The winner is the mouse which completes any one of its three runs in the shortest time.

Effects of sex and strain on exploratory locomotion and development of nonreinforced maze patrolling

Continuous recording of locomotion in an enclosed maze with no reinforcement other than that intrinsic to ambulation through the maze provided evidence for a dissociation between the efficiency of patrolling the entire maze and locomotor activity. Patrolling efficiency improved with repeated exposure to a single maze or to two similar maze configurations but not with daily presentation of dissimilar mazes. There were only small strain and sex differences in the development of efficient patrolling, whereas locomotor activity was considerably higher in female Roman high-avoidance (RHA) rats than in female Roman low-avoidance rats and higher in RHA female rats than in RHA male rats.

Prolonged Gamma Irradiation as Related to Learning and Motivation in the Rat

Three groups of rats, matched on the basis of their performance on the first eight choice points of a seventeenunit elevated T-maze, were exposed to prolonged gamma in irradiation for 4, 9, and 13 weeks, respectively. Subgroups in each irradiation-duration group received one of the following experimental conditions: no irradiation (control); exposure to 3 r/week; exposure to 30 r/ week; or exposure to 300 r/week. Posttreatment testing on the entire maze revealed a significantly faster mean running speed for animals exposed to 3 r/ week for 13 weeks. Error measures were not related to radiation treatment at any time. It was concluded that changes in motivation were responsible for the observed behavioral differences. (auth)

Effect of Chlorpromazine on Discrimination and Reversal Learning in the White Rat

The literature concerning the effects of chlorpromazine on basic psychological processes has been concerned primarily with problems involving the acquisition or retention of conditioned emotional behavior (5, 6) . The present report deals with a study of the effects of two dose levels of chlorpromazine on speed of learning a black-white discrimination, a learning problem which may be considered to be non-emotional as compared, for example, with gridshock motivated responses. METHOD Sabjects.-30 male albino rats of the Wistar strain between 90 and 100 days of age were divided into three groups and handled for 15 to 20 min. daily for 10 days prior to drug administration. Throughout the study Ss were fed 10 mg. per day of powdered Purina Dog Chow mixed 1:2 with water by weight at 10:OO p.m. For three days prior to the learning trials animals were in the apparatus for one-half hour where food was available in the goal compartments. Apparatu.r.-A Y-maze with a start box of 8 in., approach of 23 in., and choice alleys of 22 in. was used. It was 5 in. wide and 8 in. deep throughout. The entire maze was painted grey and was covered with hardware cloth which was hinged over the start and goal boxes. One door was white, the other black, with their positions varied during each day's trials following Hilgard ( 7 ) . The correct door could swing free and the incorrect door was blocked. The reward ( . l mg. of wet mash) was placed at the rear of the appropriate goal box. Light was provided by a 40-w bulb 10 in. above the choice point.