T-maze Behavior Research Articles

Cortical and hippocampal dynamics under logical fragmentation of environmental space

Navigation is often constrained to pathways, and a recurring problem concerns whether to turn left or right when approaching an intersection. We examined this problem during T-maze performance in which the maze location in the recording environment varied over five-trial blocks and analyzed the associated positional firing patterns of hippocampal CA1 and posterior parietal cortex neurons. An arbitrary partitioning of the environmental space determined the left versus right turning rule for T-maze behavior. Under these conditions, rats learned the logical fragmentation of allocentric space into left turn and right turn sub-regions. Paradoxically, under these conditions, the spatial tuning of both posterior parietal cortex and hippocampal CA1 neurons followed the frame of reference given by the T-maze, as opposed to the location in the environment. Moreover, first trials within each block were associated with distinct firing rate changes for both posterior parietal cortex and hippocampal CA1 neurons. These data support a model where spatial tuning by hippocampus and cortex can interact to guide choice behavior in complex, path-based environments where a correct turn choice varies across environmental locations, and as a function of recent experience.

Embelin Protects Against Acute Pentylenetetrazole-Induced Seizures and Positively Modulates Cognitive Function in Adult Zebrafish.

Purpose of the research: Epilepsy is a continuous process of neurodegeneration categorized by an enduring tendency to generate uncontrolled electrical firing known as seizures causing involuntary movement all over the body. Cognitive impairment and behavioral disturbances are among the more alarming co-morbidities of epilepsy. Anti-epileptic drugs (AEDs) were found to be successful in controlling epilepsy but are reported to worsen cognitive status in patients. Embelin (EMB) is a benzoquinone derived from the plant Embelia ribes and is reported to have central nervous system (CNS) activity. This study aims to evaluate the effectiveness of EMB against pentylenetetrazole (PTZ) induced acute seizures and its associated cognitive dysfunction. This was done via docking studies as well as evaluating neurotransmitter and gene expression in the zebrafish brain. The principal results: Behavioral observations showed that EMB reduced epileptic seizures and the T-maze study revealed that EMB improved the cognitive function of the fish. The docking study of EMB showed a higher affinity toward gamma-aminobutyric acid (GABAA) receptor as compared to the standard diazepam, raising the possibility of EMB working via the alpha subunit of the GABA receptor. EMB was found to modulate several genes, neurotransmitters, and also neuronal growth, all of which play an important role in improving cognitive status after epileptic seizures. Healthy zebrafish treated with EMB alone were found to have no behavioral and biochemical interference or side effects. The immunohistochemistry data suggested that EMB also promotes neuronal protection and neuronal migration in zebrafish brains. Major Conclusions: It was perceived that EMB suppresses seizure-like behavior via GABAA receptor pathway and has a positive impact on cognitive functions. The observed effect was supported by docking study, T-maze behavior, neurotransmitter and gene expression levels, and immunohistology study. The apparatus such as the T-maze and seizure scoring behavior tank were found to be a straightforward technique to score seizure and test learning ability after acute epileptic seizures. These research findings suggest that EMB could be a promising molecule for epilepsy induced learning and memory dysfunction.

Effects of hypoxic preconditioning on memory evaluated using the T-maze behavior test

ABSTRACTPerioperative brain ischemia and stroke are leading causes of morbidity and mortality. Brief hypoxic preconditioning is known to have protective effects against hypoxic-ischemic insult in the brain. Current studies on the neuroprotective effects of ischemic preconditioning are based on histologic findings and biomarker changes. However, studies regarding effects on memory are rare. To precondition zebrafish to hypoxia, they were exposed to a dissolved oxygen (DO) concentration of 1.0 ± 0.5 mg/L in water for 30 s. The hypoxic zebrafish were then exposed to 1.0 ± 0.5 mg/L DO until the third stage of hypoxia, for 10 min ± 30 s. Zebrafish were assessed for memory retention after the hypoxic event. Learning and memory were tested using the T-maze, which evaluates memory based on whether or not zebrafish moves to the correct target compartment. In the hypoxic preconditioning group, infarct size was reduced compared with the hypoxic-only treated zebrafish group; memory was maintained to a degree similar to that in the hypoxia-untreated group. The hypoxic-only group showed significant memory impairments. In this study, we used a hypoxic zebrafish model and assessed the effects of ischemic preconditioning not only on histological damages but also on brain function, especially memory. This study demonstrated that a brief hypoxic event has protective effects in hypoxic brain damage and helped maintain memory in zebrafish. In addition, our findings suggest that the zebrafish model is useful in rapidly assessing the effects of ischemic preconditioning on memory.

Adding preferred color to a conventional reward method improves the memory of zebrafish in the T-maze behavior model

ABSTRACTZebrafish have become a useful model for studying behavior and cognitive functions. Recent studies have shown that zebrafish have natural color preference and the ability to form associative memories with visual perception. It is well known that visual perception enhances memory recall in humans, and we suggest that a similar phenomenon occurs in zebrafish. This study proposes that adding a visual perception component to a conventional reward method would enhance memory recall in zebrafish. We found that zebrafish showed greater preference for red cellophane over yellow in the training session but could not remember the preferred place in the memory test. However, the test memory recall was greater when the zebrafish were exposed to the red cellophane with a food reward during the training session, when compared with the use of food reward only. Furthermore, the red cellophane with food reward group showed more predictable memory recall than the food reward only group. These results propose that visual perception can increase memory recall by enhancing the consolidation processes. We suggest that color-cued learning with food reward is a more discriminative method than food reward alone for examining the cognitive changes in the zebrafish.Abbreviations: WM: working memory; LTM: long-term memory

Selective effect of allopregnanolone on corticoliberin-induced anxiety.

We studied the effect of allopregnanolone on stress-induced anxiety caused by intranasal administration of corticoliberin to male Wistar rats. Active and passive rats were selected by their T-maze behavior and then were tested in elevated plus maze for initial anxiety level. Basing on test results, the animals were divided into following groups: active high-anxiety rats, active low-anxiety rats, and passive animals. Rats of the experimental subgroups received subcutaneous injection of allopregnanolone (0.2 mg/kg body weight), control animals received saline. In 30 min, all animals intranasally received corticoliberin (0.5 μg into each nostril) and then were tested in elevated plus maze. Passive animals demonstrated increased anxiety after corticoliberin administration against the background of allopregnanolone. Under the same conditions, low-anxiety rats demonstrated reduced anxiety, while in active high-anxiety animals, only an increase of motor activity was observed. Hence, the effect of allopregnanolone on anxiety level under stress conditions depends on individual typologic features of animal behavior.

CHEMOSIGNALING IN CBA AND C57BL/6 MOUSE STRAINS IS MODIFIED BY STRESS

Chemosignaling is widespread among animals as tool for regulation of synecological interactions. Evolutional conservatism of such signaling allows us to suggest that same chemosignals play an important role in different animal species including human beings. Aversion/attraction of mouse pheromone 2,5- dimethylpyrazine (2,5-DMP) and 2,3-dimethylpyrazine (2,3-DMP) for CBA and C57BL/6 mice was studied in T-maze. It is shown that intact males and females of both strains under choice condition prefer 2,3-DMP to water and 2,5-DMP. They also prefer water to 2,5-DMP Stress after swimming modifies behavior in T-maze: all preferences disappear in C57BL/6 males and remain without changes in CBA males. Importance of behavioral changes obtained here under stress condition is discussed. Detailed studies of the preference modulation with recently shown other effects of 2,5-DMP could connect specific sensitivity to chemosignals with the pheromone, stress and genotype.

Early T-maze behavior and broiler growth

In the laboratory and at a commercial farm in Argentina, chicks that showed a short latency to exit a T-maze (LEX) (HP, high performance) gained more weight than those with a longer LEX (LP, low performance). The present study re-examined this relationship and evaluated additional T-maze measures using broilers reared in quasi-intensive, environmentally controlled conditions. In the T-maze, a mirror strategically placed at the end of a corridor stimulates the test chick to leave the isolation chamber (start box) and to move toward its reflection. Having done so, it can then see other birds and thereby be further stimulated to completely exit the maze. However, when a test bird hesitates or stops at the mirror, its performance categorization may be confounded. Herein, the T-maze performance of 3-d-old broiler chicks was assessed using three different measurements: 1) the latency to exit the start box (LEB), 2) the latency to reach the mirror section of the maze (LRM), and 3) LEX. The fastest (top 25%) and slowest (bottom 25%) of the birds within a sex and within each of the three T-maze criteria were classified as HP and LP chicks, respectively. The relationships between these measures and body weight were examined in 4-, 42-, and 56-d-old males and females. Irrespective of the T-maze classification criteria used, HP and LP chicks had similar body weights at 4 d of age. However, chicks classified as HP according to LEB or LRM measures were heavier at 42 and 56 d of age than LP ones (P < 0.02 for all comparisons). These differences were apparent in both sexes. On the other hand, there were no detectable differences in body weight at the latter ages between chicks categorized as HP or LP according to their LEX scores. The present results indicate that 1) broiler chicks that exit the T-maze start box and reach the mirror quickly subsequently grow faster than their slower LP counterparts and 2) LEB and LRM are better predictors of growth than the LEX value used in previous studies.

T-maze behavior and early egg production in Japanese quail selected for contrasting adrenocortical responsiveness

Broiler chicks that traverse a T-maze quickly to reinstate contact with their companions (HP, high performance) are known to grow faster, be more social, and exhibit a reduced plasma corticosterone (B) response to acute stress than slower (LP, low performance) chicks. Genetic lines of Japanese quail selected for reduced (LS, low stress) or exaggerated (HS, high stress) plasma B response to brief restraint also differ in sociality and performance. In the present study, we asked if divergence in early T-maze behavior was associated with differential attainment of puberty and early egg production in these lines. At 3 d of age, LS and HS quail were categorized as HP or LP birds based on running times in a T-maze. Thus, there were four treatment combinations: HP-LS, HP-HS, LP-LS, and LP-HS birds. Daily egg records were kept for 8 wk. The average ages at first egg lay (FIRST), at 25% egg production (A25% EP), and weekly and cumulative hen-day egg production (HDEP) where calculated. Daily egg weight (EWT) data were also collected, and BW measures were made at the end of the trial. Mean FIRST and A25% EP responses were lower (P < 0.02) and cumulative HDEP was greater (P < 0.04) in HP than in LP quail. Despite considerable numerical reductions in FIRST and A25% EP, as well as 5% elevation in cumulative HDEP in LS quail, line differences in these variables were not significant. On the other hand, FIRST and A25% EP were reduced (P < 0.05) in HP-LS quail when compared to LP-HS ones, whereas HP-HS and LP-LS quail showed intermediate and similar responses that did not differ from the other two treatment groups. Mean cumulative HDEP findings for the interactive effect of performance category with line mimicked these puberty findings. EWT and BW measures were not affected by any of the treatments or their interactions. Our results suggest that rapid negotiation of the T-maze by quail chicks is associated with accelerated puberty and increased HDEP in quail of two genetically diverse lines. This effect is particularly evident in quail selected for reduced adrenocortical responsiveness, suggesting possible additive effects.

T-maze behaviour in broiler chicks is not sensitive to right–left preferences, test order or time-of-day

There is substantial individual variation in the time taken by broiler chicks to traverse a T-maze and thereby reinstate visual contact with their companions. Chicks completing this task quickly (high performance, HP) subsequently grew faster in the laboratory and on farm, exhibited greater sociality, and showed less pronounced adrenocortical responses to a partial water immersion stressor than did their slower (low performance, LP) counterparts [Marin, R.H., Jones, R.B., 1999. Latency to traverse a T-maze at 2 days of age and later adrenocortical responses to an acute stressor in domestic chicks. Physiol. Behav. 66, 809–813.; Marin, R.H., Arce, A., Martijena, I.D., 1997. T-maze performance and body weight relationship in broiler chicks. Appl. Anim. Behav. Sci. 54, 197–205.; Jones, R.B., Marı́n, R.H., Garcı́a, D.A., Arce, A., 1999. T-maze behaviour in domestic chicks: a search for underlying variables. Anim. Behav. 58, 211–217.]. Given its simplicity, rapidity and non-invasiveness, the T-maze test might represent a commercially attractive selection criterion for future breeding programmes if this behavioural trait exhibits sufficient genetic variability. However, it is first necessary to ensure that performance in the T-maze is not sensitive to potentially confounding variables, such as existing preferences to turn right or left at the junction of the maze, the order of testing, or the time of day. In the present study, 240 newly hatched, mixed-sex broiler chicks (Cobb) were randomly allocated to 12 groups of 20 upon receipt. When they were 2 days of age a group of 20 chicks was placed in the brood area of each of two T-mazes at 0830 h; the brood areas were positioned on either the right or the left sides of the mazes. After acclimatisation, one chick from each group was placed in the isolation chamber of the T-maze and we recorded the time it took to traverse the maze. This procedure was repeated until all 20 chicks and all 12 groups had been tested. The locations of the brood areas were rotated after each block of 20 tests. Testing was completed in the same day and two groups were tested at each of the following times: 0900, 1030, 1200, 1330. 1500, and 1630 h. Analyses of variance (ANOVA) revealed no detectable effects of: positioning the brood area on the right or the left side of the T-maze ( F 1,200=0.06, P<0.80), test order ( F 19,200=0.48; P<0.96), or time-of-day ( F 5,234=0.44; P<0.81). These findings strongly suggest that the future classification and possible selection of broiler chicks according to their T-maze responses are unlikely to be confounded by right–left preferences, test order, or the time of day.

Early T-maze behaviour and subsequent growth in commercial broiler flocks

1. Two batches of 2000 mixed-sex broiler chicks were obtained, one in summer and one in winter. Each flock was housed on the floor at a commercial farm. At 2 or 3 d of age, the latencies to escape from a T-maze were measured in 1044 and 1180 chicks in the summer and winter flocks, respectively . Chicks were assigned to high (HP), moderate (MP) or low (LP) performance categories if their escape latencies were below 40 s, between 40 to 90 s, or above 90 s, respectively. 2. Ninety male and 90 female chicks from each of the 3 categories were weighed when they were 3 d old. The birds then remained undisturbed, apart from routine maintenance, until similar numbers were weighed at 49 d of age. Some birds may have been weighed at both ages. 3. Body weights were higher in males than females and higher in the winter than summer flock at 3 d of age. 4. Significant main effects of chick category as well as gender and season were found at 49 d of age. There were no significant interactions. As expected, 49-d body weights were higher in males than females and in the flock reared in winter than in summer. 5. HP chicks (those that showed rapid escape from the T-maze at 3 d) were also significantly heavier at 49 d than their LP counterparts, with MP chicks occupying an intermediate position. This suggests that early performance in a T-maze test is positively associated with subsequent growth. Furthermore, this relationship was apparent in each of the 2 flocks. 6. Given this positive association, we suggest that this simple, rapid and non-invasive behavioural test could be a useful selection criterion for future breeding programmes.

T-maze behaviour in domestic chicks: a search for underlying variables

We investigated whether contrasting T-maze behaviour shown by domestic chicks, Gallus gallus domesticus , of a broiler strain reflected underlying differences in their general activity levels, fearfulness or sociality. The time taken by 2-day-old chicks to traverse a T maze and thereby regain visual contact with their companions was measured. Chicks were categorized according to whether they completed this task quickly (HP, high performance, <25s) or slowly (LP, low performance, >75s) and then housed in same-category groups, each of eight chicks. In experiment 1, we compared the numbers of HP and LP chicks showing certain home cage behaviours (ambulation, standing, resting, maintenance, pecking, preening). No significant differences were found. In experiment 2, we compared the behaviour of HP and LP chicks in two tests of sociality (home cage proximity, runway) and in two tests of fear (emergence, tonic immobility). The HP chicks stayed closer together in the home cage than did their LP counterparts and they spent significantly longer near a goal box containing conspecifics in the runway than did LP ones. Conversely, there were no significant differences between HP and LP chicks in their latency to emerge from a sheltered area into an exposed and, hence, potentially frightening one or in their tonic immobility fear reactions. These findings suggest that contrasting T-maze performance was unlikely to have reflected differences in underlying activity levels or in fearfulness. Conversely, individual variation in underlying sociality was probably an influential variable.

The effects of early stress and undernutrition on the behavior of young adult rats and the correlations between behavioral and brain parameters

Control and chronic undernourished newborn rat pups were exposed to cold stress for 3 min daily or left undisturbed on Days 2–11. On Days 25–29 (preweaning) and at 90 days of age, stressed and non-stressed pups in each group were tested in a cross-maze and a T-maze, and their preference for novel and social stimulation and activity levels were measured. At 90 days only, another group of such pups was trained to learn an active avoidance response to electric shock. The results on maze performance show that prior to weaning, stressed controls (SC) and nonstressed undernourished (NSU) pups exhibited shorter response latencies, and a greater preference for social stimulation than the non-stressed controls (NSC). At 90 days, SC and NSU again exhibited shorter latencies, and higher activity levels, and also a greater preference for novel stimulation than the NSC animals. In these parameters, there were no significant differences between stressed undernourished (SU) and NSU animals. In original avoidance learning, undernourished animals exhibited a slower rate of acquisition learning than controls. However, in reversal learning, NSU animals made significantly more errors than the SU animals. There were no significant differences between the two control groups and the SU group. These results show that early cold stress alone can have the same behavioral effects as early undernutrition alone and that early stress can have a significant reversing effect on the learning performance of previously undernourished adult animals. Statistical correlations between behavioral parameters (X- and T-maze behavior and active avoidance learning) and crude brain parameters (weight, cell number (DNA), cell density and protein) were investigated in the above animals. It was found that, in general, behavioral parameters whose high values appear to be of advantage for the animal (e.g. number of entries or social time in mazes and percent correct moves in the original and reversal learning) had significant positive correlations with weight, cell number (DNA), and protein content, at least in cerebral cortex and cerebellum, and negative correlations with cortical cell density. Conversely, parameters whose high values are of disadvantage (latency in mazes, or total trials to criterion and total errors in learning) generally had significant negative correlations with brain weight, cell number, and protein content, and positive with cortical cell density. Age, stress or undernutrition had no effect on these results. It is concluded that, statistically, even these crude brain parameters may be significantly correlated with behavior. That is, animals tend to perform better if their cortical cells are further apart and if their brain weight, cell number (DNA), and protein content are higher.

Behavioural studies on the effects of d-amphetamine and estradiol benzoate alone and in combination

The effects of d-amphetamine sulphate on grooming, rearing, and ambulatory behaviour in the T-maze was studied in rats. Low doses (0.25-2.0 mg/kg) produced a dose-dependent change in behaviour; ambulatory behaviour was increased while grooming and rearing behaviour was decreased. The results suggest that the behavioural changes are a direct effect of amphetamine rather than a secondary consequence of a competition between different types of behaviour. The effects of d-amphetamine sulphate and/or estradiol benzoate on grooming, rearing, and ambulatory bheaviours in the T-maze and open field were also studied. Rats chronically treated with estradiol or oil were injected with amphetamine or saline just prior to evaluation in the maze or open field. Amphetamine treatment, irrespective of environment or hormone treatment, stimulated ambulatory behaviour while inhibiting grooming behaviour. Estradiol specificially antagonized the amphetamine induced reduction of grooming in the maze only. The results suggest that amphetamine has an independent action on T-maze behaviour whereas estradiol has an effect that depends on the environment for its manifestation.

Effect of desglycinamide-lysine vasopressin (DG-LVP) on sexually motivated T-maze behavior of the male rat

Desglycinamide lysine vasopressin (DG-LVP), a vasopressin analog which has been found to facilitate the maintenance of active and passive avoidance behavior, influences the retention of a sexually motivated choice behavior of male rats in a T maze. A higher percentage of rats receiving DG-LVP after each acquisition session shows a correct choice during free-choice retention trials. The total number of correct choices is also higher than in the controls. Copulation reward after a correct choice is an essential requisite for acquiring the choice response and retention effect of DG-LVP. Male rats which were prevented from copulating with the receptive female goal rat or which were presented with another male in the goal box did not acquire the response, and their behavior was not influenced by DG-LVP. Response latencies were never affected by the peptide. It is concluded that the long-term effect of vasopressin on learned behavior is of a rather general nature and is most probably due to facilitated memory consolidation processes.

Effects of runway training on behavior in the T-maze

Two experimental groups (E1 and E2) were first trained in a runway before being transferred to a T-maze in which they received the same number of acquisition trials as a control group (C), which had no prior runway training. Group E2 differed from Group E1 in that it received extinction trials in the runway before being transferred to the T-maze. None of the three groups received any pretraining in either apparatus. It was found that Group E2 made significantly more correct choices in the T-maze than either Group El or Group C. Similarly, Group E1 was superior to Group C. These results, in conjunction with other similar findings, point to the importance of investigating runway training as a potent independent variable having marked effects upon T-maze behavior.