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At least 109 records · Page 6Linked to original sources

PubMed2006

Spatial navigation in complex and radial mazes in APP23 animals and neurotrophin signaling as a biological marker of early impairment.

Impairment of hippocampal function precedes frontal and parietal cortex impairment in human Alzheimer's disease (AD). Neurotrophins are critical for behavioral performance and neuronal survival in AD. We used complex and radial mazes to assess spatial orientation and learning in wild-type and B6-Tg(ThylAPP)23Sdz (APP23) animals, a transgenic mouse model of AD. We also assessed brain content of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3). Performance was alike in wild-type and APP23 animals in the radial maze. In contrast, performance in the complex maze was better in wild-type than APP23 animals. Contrary to the wild-type, hippocampal BDNF levels decreased on training in APP23 animals. Hippocampal and frontal cortex NGF levels in APP23 animals correlated with the time to solve the complex maze, but correlated inversely with escape time in wild-type animals. NT-3 levels were alike in wild-type and APP23 animals and were unchanged even after training. Both types of mazes depend on hippocampal integrity to some extent. However, according to the cognitive mapping theory of spatial learning, the complex maze because of the increased complexity of the environment most likely depends more strongly on preserved hippocampal function than the radial maze in the working memory configuration applied here. Greater impairment in complex maze performance than in radial maze performance thus resembles the predominant affliction of the loss of hippocampal function in human AD. NGF and BDNF levels on maze learning are different in wild-type and transgenic animals, indicating that biological markers of AD may be altered on challenge even though equilibrium levels are alike.

Amyloid beta-Protein Precursor↗

PubMed2006

Brain activation during mental maze solving.

BACKGROUND: So-called Porteus mazes are used to investigate prefrontal cortex (PFC) functioning in normal subjects and patients with different neuropsychiatric disorders. Here we present data confirming the involvement of the PFC for the first time by means of functional magnetic resonance imaging (fMRI). To minimize motor-related activation, mental mazes were used. METHODS: Mazes as well as pseudo-mazes without any bifurcations were presented to 49 healthy participants during fMRI scans. RESULTS: Both, mazes as well as pseudo-mazes, activated a large network from visual to parietal regions, reflecting the dorsal stream of visual information processing. Mazes but not pseudo-mazes also activated bilateral areas of the PFC indicating their special role in decision processes. In addition, although no motor response was required during maze performance, both tasks activated subcortical and cortical motor areas. CONCLUSIONS: These tasks are suitable for investigating and specifying PFC functioning and its impairment in psychiatric disorders such as schizophrenia. In addition, mental mazes might be a suitable task for the investigation of patients with motor disturbances.

Adolescent↗

PubMed1976

Genetic and environmental correlations between brain weight and maze learning in inbred strains of mice and their F1 hybrids.

The relationships among body weight, cerebellum weight, cerebrum weight, maze-learning ability in a double T-maze, and discrimination learning in a Y-maze were studied in six inbred strains of mice and some of their F1 hybrids. The subjects were 131 male albino mice from 14 genotypic groups: five inbred groups and nine groups of crossbred offspring. Intra- and intergroup correlations were computed between all possible pairs of the anatomical and behavioral traits. A significant difference between the intragroup and intergroup correlations for any pair of variables was taken to indicate the presence of a genetic correlation between the two variables. On this basis, positive genetic correlations were indicated between T-maze learning ability and Y-maze learning ability, between body weight and T-maze learning ability, and possibility between body weight and both cerebellum and cerebrum weight and between cerebrum weight and T-maze learning ability. Negative genetic correlations were indicated between cerebellum weight and running time in both mazes and between total number of successes in the Y-maze and Y-maze running time.

Animals↗

PubMed2006

Role of the simultaneous sequential strategy for failed acute sinus restoration after modified left maze procedure for persistent atrial fibrillation with concomitant mitral surgery.

BACKGROUND: We assessed whether the simultaneous sequential strategy could (1) achieve additional sinus restoration for those patients who were not in sinus rhythm while coming off bypass after modified left maze procedure and (2) attain the same long-term success rates as the bi-atrial maze procedure in patients with persistent atrial fibrillation (AF) and mitral valve disease. MATERIALS AND METHODS: Twenty-seven consecutive patients - ten men and 17 women with a mean age of 52 +/- 13 years, all with persistent AF and mitral valve disease - underwent the modified maze procedure with the simultaneous sequential strategy. In the first phase, the modified left atrial maze operation was carried out with concomitant valvular surgery; the right side maze operation was subsequently carried out as a second phase of the sequential strategy only if AF re-appeared following the spontaneous restoration of heart beats during the operation. RESULTS: Twenty patients (74.1%) underwent the left atrial maze procedure only, and seven patients (25.9%) required the subsequent right atrial maze procedure as part of the sequential strategy. At a mean follow-up of 15.1 +/- 7.7 months, six of the 27 patients (22.2%) who underwent additional right atrial maze procedure had restored sinus rhythm. At a mean follow-up of 17.8 +/- 7.3 months, 24 of the 27 patients (88.9%) had restored sinus rhythm and 22 patients (81.5%) had restored bi-atrial transport function (right atrial filling fraction: 40.8 +/- 11.7%; left atrial filling fraction: 22.9 +/- 8.1%) after application of the sequential strategy. CONCLUSIONS: Compared with modified left atrial maze procedure, the application of the simultaneous sequential strategy successfully restored sinus rhythm in an additional 22.2% of patients with persistent AF. The overall sinus conversion rate of 88.9% was comparable with that of the standard bi-atrial maze procedure.

Adult↗

PubMed1993

Effects of psychoactive drugs or stress on learning, memory, and performance as assessed using a novel water maze task.

A novel water maze was used to assess the potential performance-disrupting effects of psychoactive drugs and stressors (4 mg/kg amphetamine sulfate; 1, 2, or 4 mg/kg diazepam; 30 mg/kg caffeine; 5 or 30 mg/kg atropine sulfate; 15 min of either intermittent foot-shock, forced running, or immobilization). The task utilized a traditional type of maze with walls and doorways set inside a pool. The apparatus could easily be reconfigured to present different mazes of approximately equal difficulty by opening or closing multiple doorways. Performance was measured by number of errors and time required to swim from the "start" to "finish" (a raised platform not in the rat's line of sight). After initial maze training, rats were divided into two groups. One group ran three daily trails through the same maze each day; this group was used to assess memory. The second group was challenged to swim three consecutive trials in a new maze configuration each day as a measure of learning. On any given day, rats from both groups received the same treatment. Drug or stress treatments were interspersed with vehicle or no-treatment trials days. The new maze task was more sensitive than the well-learned maze to the performance disrupting effects of amphetamine, caffeine, and diazepam, while atropine had no significant effect on performance on either maze. Foot-shock stress impaired performance on both mazes, while the other stressors had no significant effect.

Acute Disease↗

PubMed2004

A prospective, single-center clinical trial of a modified Cox maze procedure with bipolar radiofrequency ablation.

OBJECTIVE: The Cox maze III procedure has excellent long-term efficacy in curing atrial fibrillation. It has not been widely practiced because it is technically challenging and requires prolonged cardiopulmonary bypass. The aim of this study was to examine a simplified Cox maze III procedure that uses bipolar radiofrequency energy as an ablative source. METHODS: Beginning January 2002, a total of 40 consecutive patients underwent a modified Cox maze III procedure with bipolar radiofrequency energy. Nineteen had a lone maze procedure and 21 had a maze procedure plus a concomitant operation. One month after the operation, the first 8 patients were investigated with high-resolution magnetic resonance imaging. Patients were followed up monthly with clinical examination and electrocardiography. RESULTS: There was no operative deaths. The crossclamp times were 47 +/- 26 minutes for the modified lone Cox maze III procedure and 92 +/- 37 minutes for the Cox maze III procedure plus concomitant procedures. These were significantly shorter than our previous times for the traditional Cox maze III procedure (93 +/- 34 minutes and 122 +/- 37 minutes, respectively, P <.05). Follow-up magnetic resonance imaging showed no evidence of pulmonary vein stenosis, and atrial contractility was preserved in all patients. There were no late strokes. At 6-month follow-up, 91% of patients (21/23) were in sinus rhythm. CONCLUSIONS: Bipolar radiofrequency ablation can be used to replace the surgical incisions of the Cox maze procedure. This energy source did not result in pulmonary vein stenosis. The modification of the Cox maze III procedure to use bipolar radiofrequency ablation simplified and shortened this procedure without sacrificing short-term efficacy.

Atrial Fibrillation↗

PubMed1996

Rationale of the Cox maze procedure for atrial fibrillation during redo mitral valve operations.

OBJECTIVE: The frequency of reoperation for mitral valve diseases with chronic atrial fibrillation has increased steadily. This study examined the rationale for using the Cox maze operation for atrial fibrillation during redo mitral valve operations. METHODS: Between June 1992 and July 1995, we performed the maze procedure in 42 patients as a concomitant operation with redo mitral valve surgery (maze group). Associated procedures were tricuspid valve surgery in 27 patients and aortic valve surgery in 15 patients. The mean age at operation was 57.3 +/- 9.7 years, and the mean interval from the previous operation was 14.3 +/- 10.5 years. The mean follow-up period after the maze procedure was 25.5 +/- 10.8 months. Atrial fibrillation was present at the time of the previous operation in 29 patients (69%). RESULTS: Neither hospital death nor late death occurred. Sinus rhythm was regained in 28 patients (67%), and an atrial A-wave was detected in 21 patients (50%) by pulsed Doppler study. Patients in whom sinus rhythm was restored had a shorter history of atrial fibrillation (9.0 +/- 6.0 years vs 15.9 +/- 4.6 years, p = 0.0009), a larger f-wave on lead V1 of the electrocardiogram (0.18 +/- 0.10 mV vs 0.10 +/- 0.08 mV, p = 0.017), and a smaller cardiothoracic ratio (63% +/- 8% vs 67% +/- 5%, p = 0.049) than patients with persistent atrial fibrillation. During the same period, 54 patients underwent mitral valve reoperation without the maze procedure (control group). The aortic crossclamp and cardiopulmonary bypass times were slightly longer (p = 0.048 and p = 0.012) in the maze group (133 +/- 28 minutes and 221 +/- 43 minutes) than in the control group (126 +/- 65 minutes and 197 +/- 78 minutes). There was no significant difference in the amount of chest tube drainage or transfusion between the two groups (890 +/- 510 ml and 2120 +/- 1600 ml, respectively, in the maze group and 840 +/- 480 ml and 2140 +/- 1760 ml, respectively, in the control group). It was not necessary to reopen the chest for bleeding significantly more often in one group than in the other (14% in the maze group and 7% in the control group), and it was possible to operate without transfusion with the same frequency in the two groups (17% in the maze group and 20% in the control group). CONCLUSION: These results suggest that the maze procedure should be considered in selected patients who have a high possibility of regaining sinus rhythm during redo mitral valve operations.

Adult↗

PubMedDate not supplied

Left and right atrial transport function after the Maze procedure for atrial fibrillation: an echocardiographic Doppler follow-up study.

OBJECTIVES: We evaluated atrial transport function after the Maze procedure in long-term follow-up and compared left and right atrial function in Maze patients with that of healthy age-matched controls using echo Doppler techniques. BACKGROUND: The Maze procedure is designed to eliminate atrial fibrillation, restore normal sinus rhythm, and preserve atrial contraction. Initial data indicate that atrial transport function is restored in most patients undergoing the Maze procedure. The long-term echo Doppler evaluation of patients after the Maze procedure has not been well described. METHODS: We performed pulsed-wave Doppler and two-dimensional echocardiographic studies on 31 patients (24 men, mean age 53.8 years) who underwent the Maze procedure and who had a follow-up study greater than 3 months (mean 16.5 months) after the procedure. Measurements included peak left ventricular and right ventricular inflow A-wave velocity, maximum and minimum left atrial and right atrial areas, and fractional area change of the left and right atria. Results were compared with those obtained from 15 age-matched control subjects (11 men, mean age 53.8 years). RESULTS: Twenty-two patients (71%) had left atrial function shown by the presence of left ventricular inflow A-wave, and 25 patients (81%) had right atrial function shown by the presence of right ventricular inflow A-wave on Doppler echocardiography. The left ventricular inflow A-wave velocity was significantly lower than that of age-matched controls (37.5 +/- 15.5 versus 61.0 +/- 13.9 cm/sec; p < 0.001), whereas the right ventricular inflow A-wave velocity did not significantly differ between patients and control subjects (35.4 +/- 9.9 versus 35.3 +/- 4.9 cm/sec; p = Not significant). Although left and right atrial areas decreased significantly after the procedure, there was no significant change in the fractional area change which was smaller in Maze patients than control individuals. CONCLUSIONS: (1) In long-term follow-up of 16.5 months after the Maze procedure, left atrial systolic function was preserved in 71% of our patients and right atrial systolic function was preserved in 81%; (2) the left ventricular inflow peak A-wave velocity after Maze is considerably less than that in age-matched controls; and (3) left and right atrial sizes decreased after the procedure with no change in the fractional area change. These findings suggest that the Maze procedure is effective in restoring atrial function in the majority of patients; however, restored function is less than in control individuals.

Adult↗

PubMed2000

The Cox-Maze procedure: the Cleveland Clinic experience.

The Cox-Maze procedure was designed to address the consequences of atrial fibrillation, tachycardia, hemodynamic impairment, and thromboembolism. From 1991 until June 1999, 100 patients underwent the Maze operation at the Cleveland Clinic Foundation. The group included 72 men with a mean age of 58 +/- 11 years (range, 23 to 78 years). Initially, the Maze-I procedure was performed primarily for patients with lone atrial fibrillation. However, since 1995, the Maze-III procedure has been performed exclusively, and it is typically combined with mitral valve repair. Twenty-three patients had only a Maze procedure, 60 patients had the Maze procedure/mitral valve repair, 10 patients had Maze procedure/coronary artery bypass, 6 had Maze procedure/mitral valve replacement, and 1 had Maze procedure/atrial septal defect repair. Chronic atrial fibrillation was present in 78% of patients for a mean of 8 +/- 9 years. There was a 1% perioperative mortality and 5% late mortality rate. Median hospital stay was 9 +/- 5 days. Six patients required new early permanent pacemaker insertion. With a mean follow-up of 3 years, 90.4% of patients are in sinus rhythm (or atrial pacing). Preoperative symptoms were reduced: 24% had preoperative syncope; none had syncope in follow-up; 14% of patients preoperatively had cerebral or systemic emboli; and there were no perioperative or late embolic events. The Maze procedure effectively addressed the major complications of atrial fibrillation and was associated with low perioperative and late morbidity rates.

Adult↗

PubMed2002

Impact of Cox maze procedure on outcome in patients with atrial fibrillation and mitral valve disease.

OBJECTIVE: We sought to determine whether the Cox maze procedure provides additional benefit to patients with atrial fibrillation undergoing mitral valve operations. METHODS: Between May 1992 and August 2000, we performed 258 Cox maze procedures with mitral valve replacement (n = 147) or mitral valve repair (n = 111). We compared the outcomes of these patients with those of 61 control patients with preoperative atrial fibrillation who underwent mitral valve replacement alone during the same interval. The three cohorts were similar in age, sex, and proportion of patients in preoperative New York Heart Association functional class 3 or 4. RESULTS: Although 5-year survivals were similar among the groups (94% for mitral valve replacement alone, 95% for mitral valve replacement plus maze, and 97% for mitral valve repair plus maze), freedoms from atrial fibrillation at 5 years were significantly higher in the mitral valve replacement plus maze group (78%) and the mitral valve repair plus maze group (81%) than in the mitral valve replacement group (6%, P <.0001). Freedoms from stroke at 5 years were 97% for the mitral valve replacement plus maze group, 97% for the mitral valve repair plus maze group, and only 79% for mitral valve replacement group (P <.0001). Multivariable analysis with Cox hazard model revealed that the most significant risk factor for late stroke was the omission of the Cox maze procedure (P =.003). CONCLUSIONS: The addition of the Cox maze procedure to mitral valve repair and replacement was safe and effective for selected patients. Elimination of atrial fibrillation significantly decreased the incidence of late stroke.

Aged↗

PubMed2003

Recognition of the intrinsically flexible addiction antidote MazE by a dromedary single domain antibody fragment. Structure, thermodynamics of binding, stability, and influence on interactions with DNA.

The Escherichia coli mazEF operon defines a chromosomal addiction module that programs cell death under various stress conditions. It encodes the toxic and long-lived MazF and the labile antidote MazE. The denaturation of MazE is a two-state reversible dimer-monomer transition. At lower concentrations the denatured state is significantly populated. This leads to a new aspect of the regulation of MazE concentration, which may decide about the life and death of the cell. Interactions of MazE with a dromedary antibody domain, cAbMaz1 (previously used as a crystallization aid), as well as with promoter DNA were studied using microcalorimetric and spectroscopic techniques. Unique features of cAbMaz1 enable a specific enthalpy-driven recognition of MazE and, thus, a significant stabilization of its dimeric native conformation. The MazE dimer and the MazE dimer-cAbMaz1 complex show very similar binding characteristics with promoter DNA, i.e. three binding sites with apparent affinities in micromolar range and highly exothermic binding accompanied by large negative entropy contributions. A working model for the MazE-DNA assembly is proposed on the basis of the structural and binding data. Both binding and stability studies lead to a picture of MazE solution structure that is significantly more unfolded than the structure observed in a crystal of the MazE-cAbMaz1 complex.

Amino Acid Sequence↗

PubMedDate not supplied

The Maze procedure for the treatment of atrial fibrillation: a minimally invasive approach.

OBJECTIVES: The standard Maze procedure has proven to be extremely effective in curing atrial fibrillation in thousands of patients worldwide. Until now it has required a median sternotomy and cardiopulmonary bypass. In order to simplify the standard approach, a minimally invasive technique was developed. We have recently applied this minimally invasive Maze procedure in 72 patients. METHODS: The technique is dependent on the use of cryosurgery and the total number of atriotomies has been decreased from twelve to four. In addition to performing the Maze procedure, 32% of patients have had concomitant surgery via the minimally invasive approach including mitral valve repair/replacement and tricuspid valve repair. RESULTS: Perioperative morbidity is improved following the minimally invasive approach in comparison to the standard approach with the incidence of temporary perioperative arrhythmias being decreased by 50%. The long-term recurrence of atrial fibrillation is 2.4% following the minimally invasive Maze procedure and 2.2% following the standard Maze procedure. The incidence of pacemaker requirements following the standard Maze procedure is 20% but only 6% following the minimally invasive Maze procedure. Both right atrial and left atrial transport function have been documented in 100% of patients following the minimally invasive Maze procedure. CONCLUSIONS: We believe that the minimally invasive Maze procedure is a substantial improvement over the standard approach in terms of patient morbidity while preserving the effectiveness of the Maze procedure in curing atrial fibrillation.

Adult↗

PubMed2002

Ethanol impairs behavioral strategy use in naive rats but does not prevent spatial learning in the water maze in pretrained rats.

RATIONALE: Ethanol impairs performance in the water maze in rats. A detailed behavioral analysis is required to fully evaluate the nature of the impairment. OBJECTIVES: A detailed behavioral analysis was carried out to evaluate the effect of ethanol on performance in the water maze task in male hooded rats given 2.0 or 6.0 g/kg ethanol by gavage. Multiple measures of water maze strategies learning and spatial learning were studied. METHODS: Water maze trials were recorded on videotape and digitized for offline analysis. Some rats were naive at the start of spatial training, whereas other rats received water maze strategies pretraining prior to spatial training to familiarize them with the general behavioral strategies required in the task. RESULTS: Naive ethanol-treated rats exhibited both spatial learning and water maze behavioral strategies impairments. There was no evidence of a spatial learning impairment that was independent of an associated behavioral strategies impairment. Further, ethanol impaired the ability of naive rats to swim to a stable visible platform. Pretrained ethanol-treated rats performed significantly better than naive ethanol-treated rats on almost all measures, and were indistinguishable from controls on most measures. CONCLUSIONS: These results suggest that ethanol may impair water maze performance in naive rats by interfering with their ability to acquire and use required water maze behavioral strategies and generate adaptive swim paths. Ethanol does not prevent robust spatial learning in rats that are familiar with required water maze behavioral strategies.

Animals↗

PubMed2002

Remapping of place cell firing patterns after maze rotations.

When place cells are recorded from rats running on an elevated T-maze inside a curtained enclosure that contains distinct, experimenter selected stimuli, rotations of the maze plus stimuli cause equal rotations of firing fields. Here, we examined the effects of conflicting rotations of a T-maze relative to a laboratory frame that contained a large number of fixed stimuli in the environment and asked whether positional firing patterns stayed in register with the maze or the room cues or were modified in some more complex way. After maze rotations of 90 degrees, 180 degrees or 270 degrees, firing fields were stable in the laboratory frame and thus shifted to a different maze arm. In contrast, rotations of 45 degrees or -45 degrees resulted in dramatic changes of positional firing patterns regardless of their initial position on the maze. Crucially, even cells whose fields were initially on the central platform underwent major firing pattern alterations although the view of the environment from the platform was unchanged by such rotations. Finally, we found that altering the visual appearance by removing without rotation one or two maze arms did not alter firing fields on the remaining part of the maze. Thus, the "remappings" caused by 45 degrees rotations could result from the disturbed relationship between all arms and the room cues or from the changes in the possible paths the animal can take in the environment. Taken together, our results provide an example of combinatorial coding by the hippocampus, in which the place cell representation of the environment was seen to be modified as a unit and not piecewise according to locally available stimuli.

Animals↗

PubMed1996

Effects of the serotonin receptor agonists 8-OH-DPAT and TFMPP on learning as assessed using a novel water maze.

We evaluated the effects of two drugs active at serotonin receptors, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, a 5-HT1A agonist) and N-3-trifluoromethylphenyl)piperazine hydrochloride (TFMPP, a 5-HT2C agonist) on learning using a novel water maze previously characterized in our laboratory. The water maze utilized is a traditional type of maze with alleyways and doors through which the rats learn to swim to reach a platform, unlike the open pool Morris water maze task. Performance is assessed by swim time required to reach the platform and errors committed. Following initial training on maze configuration A, rats were assigned to saline, TFMPP and 8-OH-DPAT treatment groups and tested for performance once per dose, 30 min after administration of drug (0.25, 0.5, and 1.0 mg/kg IP). Swim times were significantly increased as compared to saline for all doses for both drugs. The error rate was increased for 8-OH-DPAT at all doses, while TFMPP had no effect on error rate at any dose. Next, rats were challenged to learn new mazes following daily administration of 0.25 or 0.5 mg/kg of each drug 30 min prior to each daily swim trial. Rats given 0.25 mg/kg of 8-OH-DPAT learned new maze C more slowly than saline-treated rats, while TFMPP had no effect at this dose. At the higher dose of 0.5 mg/kg, tested on new maze B, TFMPP administration significantly increased swim times but not errors, while this dose of 8-OH-DPAT markedly increased both swim time and errors. Finally, rats from all groups were tested on maze E after drug administration was discontinued, and there were no performance differences among groups. These data suggest that serotonin1A receptors may inhibit learning.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2000

Non-spatial water radial-arm maze learning in mice.

Recently, we published a method for examining working and reference memory in mice using a spatial version of the water radial-arm maze. Here we describe a non-spatial version of the same maze. BXSB mice were able to learn the maze as shown by the decrease in the number of working and reference memory errors over sessions. This maze was used to examine learning differences between males and females and between mice with misplaced clusters of neurons in layer I of cortex (ectopias) and those without. In a prior study using the spatial version of the water radial-arm maze, male BXSB mice had poorer working memory than females during the acquisition phase. Similarly, in this study male BXSB mice demonstrated impaired working memory during the asymptotic phase of non-spatial radial-arm maze learning. Two prior studies showed that mice with neocortical ectopias demonstrated working memory impairments compared to non-ectopic littermates in the spatial version of the water radial-arm maze. Contrary to this, in the non-spatial radial-arm maze used here, ectopic mice were not impaired in working memory and showed better memory when the working memory 'load' was the highest. Overall, both versions of the maze can be useful tools to assess spatial and non-spatial working and reference memory in mice.

Animals↗

PubMed2003

A robust animal model of state anxiety: fear-potentiated behaviour in the elevated plus-maze.

Fear (i.e., decreased percentage time spent on open-arm exploration) in the elevated plus-maze can be potentiated by prior inescapable stressor exposure, but not by escapable stress. The use of fear-potentiated plus-maze behaviour has several advantages as compared to more traditional animal models of anxiety. (a) In contrast to the traditional (spontaneous) elevated plus-maze, which measures innate fear of open spaces, fear-potentiated plus-maze behaviour reflects an enhanced anxiety state (allostatic state). This "state anxiety" can be defined as an unpleasant emotional arousal in face of threatening demands or dangers. A cognitive appraisal of threat is a prerequisite for the experience of this type of emotion. (b) Depending on the stressor used (e.g., fear of shock, predator odour, swim stress, restraint, social defeat, predator stress (cat)), this enhanced anxiety state can last from 90 min to 3 weeks. Stress effects are more severe when rats are isolated in comparison to group housing. (c) Drugs can be administered in the absence of the original stressor and after stressor exposure. As a consequence, retrieval mechanisms are not affected by drug treatment. (d) Fear-potentiated plus-maze behaviour is sensitive to proven/putative anxiolytics and anxiogenics which act via mechanisms related to the benzodiazepine-gamma-aminobutyric acid receptor, but it is also sensitive to corticotropin-releasing receptor antagonists and glucocorticoid receptor antagonists and serotonin receptor agonists/antagonists complex (high predictive validity). (e) Fear-potentiated plus-maze behaviour is very robust, and experiments can easily be replicated in other labs. (f) Fear-potentiated plus-maze behaviour can be measured both in males and females. (g) Neural mechanisms involved in contextual fear conditioning, fear potentiation and state anxiety can be studied.Thus, fear-potentiated plus-maze behaviour may be a valuable measure in the understanding of neural mechanisms involved in the development of anxiety disorders and in the search for novel anxiolytics. Finally, the involvement of corticotropin-releasing factor and corticosteroid-corticotropin-releasing factor interactions in the production of fear-potentiated plus-maze behaviour are discussed.

Animals↗

PubMed1997

PET imaging of maze processing.

Covered maze traversal models nonverbal planning, involving sequential execution of moves using learned spatial maps. To determine the neural substrate involved in maze processing, eleven adults underwent [H(2)15O]-PET while performing motor control, following the computer; visual control, choosing the wall with more dead-ends; uncovered maze, traversing fully visible mazes; covered maze, traversing mazes only locally visible. Maze processing lateralizes to the right hemisphere: uncovered maze versus controls revealed area 23 and 29 activation; covered maze versus controls activated areas 8, 10 and 19. The extrastriate region may store path information, evoked by prefrontal areas for spatial planning and navigation.

Adolescent↗