Healthy adults' performance on the Austin Maze

Association between nocturnal activity of the sympathetic nervous system and cognitive dysfunction in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is associated with repetitive breathing obstructions during sleep. These episodes of hypoxia and associated arousals from sleep induce physiological stress and nocturnal over-activation of the sympathetic nervous system (SNS). One consequence of OSA is impairment in a range of cognitive domains. Previous research into cognitive impairment in OSA have focussed on intermittent hypoxia and disrupted sleep, but not nocturnal over-activation of the SNS. Therefore, we investigated whether nocturnal over-activity of the SNS was associated with cognitive impairments in OSA. The extent of nocturnal SNS activation was estimated from heart rate variability (HRV), pulse wave amplitude (PWA) and stress response biomarkers (cortisol and glucose levels). OSA severity was significantly associated with PWA indices and the HRV low frequency/ high frequency ratio (p < 0.05). Morning blood glucose levels were significantly associated with the duration of a blood oxygen saturation (SaO₂) < 90% (p < 0.01). PWA and HRV were significantly associated with the time taken to perform a task involving visuospatial functioning (p < 0.05), but not with impairments in sustained attention, reaction time or autobiographical memory. These results suggest that the visuospatial dysfunction observed in people with OSA is associated with increased nocturnal activity of the SNS.

Differential associations of hypoxia, sleep fragmentation, and depressive symptoms with cognitive dysfunction in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete cessation of breathing during sleep and increased effort to breathe. This study examined patients who underwent overnight polysomnographic studies in a major sleep laboratory in Saudi Arabia. The study aimed to determine the extent to which intermittent hypoxia, sleep disruption, and depressive symptoms are independently associated with cognitive impairments in OSA. In the sample of 90 participants, 14 had no OSA, 30 mild OSA, 23 moderate OSA, and 23 severe OSA. The findings revealed that hypoxia and sleep fragmentation are independently associated with impairments of sustained attention and reaction time (RT). Sleep fragmentation, but not hypoxia, was independently associated with impairments in visuospatial deficits. Depressive symptoms were independently associated with impairments in the domains of sustained attention, RT, visuospatial ability, and semantic and episodic autobiographical memories. Since the depressive symptoms are independent of hypoxia and sleep fragmentation, effective reversal of cognitive impairment in OSA may require treatment interventions that target each of these factors.

Spatial sequence memory and spatial error monitoring in the Groton Maze Learning Task (GMLT): A validation study of GMLT sub-measures in healthy children

The stepping-stone variant of the hidden pathway maze learning (HPML) task paradigm has been extensively used to investigate cognitive functions in neuropsychology and neuropharmacology. Previous studies have used total error across trials, as well as rule-break errors and learning errors, to define spatial memory and/or executive function in healthy and impaired adults and children. However, the construct validity of performance measures on HPML tasks has not been established in healthy children. To assess the construct validity of measures of exploratory and rule-break errors on the Groton Maze Learning Task (GMLT) measures of spatial sequence memory (Corsi Blocks Task) and spatial error monitoring (Continuous Paired Associate Learning; CPAL) were used. The results indicate that Corsi span predicted GMLT spatial sequence memory and CPAL accuracy predicted GMLT spatial error monitoring. The construct validity of the GMLT as a measure of spatial memory and executive function are discussed with regard to prior research using HPML tasks in neuropsychological contexts.

Visuospatial Learning in Traumatic Brain Injury: An Examination of Impairments using the Computerised Austin Maze Task

An important aspect of cognitive functioning that is often impaired following traumatic brain injury (TBI) is visuospatial learning and memory. The Austin Maze task is a measure of visuospatial learning that has a long history in both clinical neuropsychological practice and research, particularly in individuals with TBI. The aim of this study was to evaluate visuospatial learning deficits following TBI using a new computerised version of the Austin Maze task. Twenty-eight individuals with moderate-to-severe TBI were compared to 28 healthy controls on this task, together with alternative neuropsychological measures, including the WAIS-III Digit Symbol and Digit Span subtests, the Trail Making Test, WMS-III Logical Memory, and Rey Osterrieth Complex Figure Test. The results demonstrated that TBI individuals performed significantly more poorly on the Austin Maze task than control participants. The Austin Maze task also demonstrated good convergent and divergent validity with the alternative neuropsychological measures. Thus, the computerised version of the Austin Maze appears to be a sensitive measure that can detect visuospatial learning impairments in individuals with moderate-to-severe TBI. The new computerised version of the task offers much promise in that it is more accessible and easier to administer than the conventional form of the test.

Disentangling the cognitive components supporting Austin Maze performance in left versus right temporal lobe epilepsy

Neuropsychological tests requiring patients to find a path through a maze can be used to assess visuospatial memory performance in temporal lobe pathology, particularly in the hippocampus. Alternatively, they have been used as a task sensitive to executive function in patients with frontal lobe damage. We measured performance on the Austin Maze in patients with unilateral left and right temporal lobe epilepsy (TLE), with and without hippocampal sclerosis, compared to healthy controls. Performance was correlated with a number of other neuropsychological tests to identify the cognitive components that may be associated with poor Austin Maze performance. Patients with right TLE were significantly impaired on the Austin Maze task relative to patients with left TLE and controls, and error scores correlated with their performance on the Block Design task. The performance of patients with left TLE was also impaired relative to controls; however, errors correlated with performance on tests of executive function and delayed recall. The presence of hippocampal sclerosis did not have an impact on maze performance. A discriminant function analysis indicated that the Austin Maze alone correctly classified 73.5% of patients as having right TLE. In summary, impaired performance on the Austin Maze task is more suggestive of right than left TLE; however, impaired performance on this visuospatial task does not necessarily involve the hippocampus. The relationship of the Austin Maze task with other neuropsychological tests suggests that differential cognitive components may underlie performance decrements in right versus left TLE.

Exploring What the Austin Maze Measures: A Comparison Across Conventional and Computer Versions

The Austin Maze is a neuropsychological assessment tool used to measure cognitive function. A computerised version of the tool has recently been developed and shown to be equivalent to the conventional version in terms of performance. However, controversy remains regarding which specific cognitive constructs the conventional and computer versions of the Austin Maze purport to measure. The aim of this study was to investigate which cognitive constructs are associated with Austin Maze performance and whether these constructs remain equivalent across conventional and computer versions. Sixty-three healthy people completed both conventional and computerised versions of the Austin Maze in addition to a number of established measures of planning, error utilisation, working memory, visuospatial ability and visuospatial memory. Results from a series of regression analyses demonstrated that both versions of the Austin Maze were predominantly associated with visuospatial ability and visuospatial memory. No executive measures, including those of planning, error utilisation or working memory, significantly contributed to any Austin Maze performances. This study complements previous research and supports equivalency of the conventional and computer versions of the Austin Maze.

Comparing Performance of Young Adults on a Computer-based Version of the Austin Maze and the Conventional Form of the Test

The Austin Maze has declined in use in both clinical and research contexts due to difficulties in accessing the conventional button-box form of the test. Computer-based versions of the Austin Maze offer a potential means of making the test more accessible, but as yet there is limited evidence regarding the equivalence of computer and conventional versions of the Austin Maze. The present study compared performance on a computer version of the Austin Maze by Bray and McDonald with performance on the traditional button maze in 63 participants aged 18–27 years. The results showed no differences between the computer and conventional versions in terms of mean scores and distributions, and performances on the two versions were significantly correlated. Examination of correlates found no relationship between Austin Maze performance and years of education or age for either version of the Austin Maze performance. Intellectual function was modestly associated with performance on the conventional version but not the computer version. Overall, these findings suggest that scores on the Bray and McDonald computer version of the Austin Maze produces comparable scores to the conventional form of the test and can be interpreted using existing normative data.

Is there more than one neuropsychological disorder commonly associated with alcohol dependence?

There are two popular neuropsychological entities commonly attributed to the effects of alcohol dependence: the well-known Wernicke-Korsakoff syndrome, and the putative alcoholic encephalopathy. Wernicke-Korsakoff syndrome is a highly variable neurological and neuropsychological disorder, which is frequently missed or misdiagnosed on clinical examination. The available prevalence figures suggest that Wernicke-Korsakoff neuropathology probably occurs with a high incidence in hospitalized alcohol-dependent people. Thus, Wernicke-Korsakoff syndrome confounds clinical descriptions of the alcoholic encephalopathy and may account for most cases presumed to suffer from the latter disorder. Even if it is assumed that there is a specific alcoholic neurotoxicity, the clinical descriptions of this condition encompass features which are all attributable to Wernicke-Korsakoff syndrome. In other words, the proponents of the alcoholic encephalopathy have failed to provide a distinctive description, thus precluding positive identification.

Cognitive impairments in the locked-in syndrome: A case report

No neuropsychologic studies have been reported that assess cognitive functioning in survivors of locked-in syndrome (LIS) due to purely pontine lesions and then document the process of recovery by serial testing over a lengthy period. A previously well man in his early thirties was admitted to the hospital with progressive stroke symptoms and signs. Investigations showed occlusion of the basilar artery and acute infarction of the pons, including basis and tegmentum. Despite thrombolysis, he had persisting clinical features of the LIS. He had minimal change during the first month but then slowly improved. Recovery continued gradually, and he was discharged home 7 months after stroke; at this time he was ambulating with a cane, was mildly dysarthric, was able to swallow foods of modified consistency, and was independent in all self-care activities. Neuropsychologic testing, done 6 months after stroke, showed noteable cognitive impairments. These included mild difficulties with attention and concentration, significant reduction in speed of processing, moderate impairment of perceptual organization skills, mild inefficiencies in new learning of verbal information, and a moderate reduction in executive skills. Pathologic laughing and crying were also noted. There was progressive improvement in most areas of physical and cognitive functioning until at least 2 years after stroke. Neuropsychologic testing in this patient suggests that the LIS may be associated with impairments of higher-level cognitive functioning.

An investigation of organic factors in the neuropsychological functioning of patients with borderline personality disorder

The hypothesis to be tested in this study was that the cognitive deficits that have been documented in patients with Borderline Personality Disorder (BPD) are largely the consequence of organic insult, either developmental or acquired. Using a cross-sectional design, 80 subjects (males and females) who met the criteria for BPD participated in the study. They completed a battery of neuropsychological tests and a comprehensive interview assessing organic status as well as measures of the potentially confounding factors of current levels of depression and anxiety. It was expected that BPD-patients with a probable history of organic insult would perform significantly worse than would BPD patients without such a history. Analyses of the results provided partial support for the hypothesis. Subjects with both BPD and a history of organic insult were significantly more impaired on several measures including measures of attention than were BPD only subjects. The results suggested that the impaired cognitive performance of persons diagnosed with BPD may, in part, be attributed to organic factors.

Neuropsychological correlates of hippocampal and rhinal cortex volumes in patients with mesial temporal sclerosis

Considerable progress has been made toward understanding the function of the primate rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices. However, translating animal models to human memory has been limited by the technological problems associated with characterizing neural structures in vivo. Functional correlates of hippocampal and rhinal cortex volume changes were examined in a sample of 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS; 33 left, 28 right). Patients were administered the Wechsler Adult Intelligence Scale (revised or third edition), the Wechsler Memory Scale (revised or third edition), and a spatial maze task. Neuropsychological data, together with rhinal cortex and hippocampal volumes, collected in our earlier study (O'Brien CE, Bowden SC, Whelan G, Cook MJ, unpublished observations), were analyzed using multiple regression. The only significant predictor of verbal memory function was the difference score between the volume of left hippocampus and the left PrC. Spatial maze scores were predicted by the bilateral sum of ErC volume. The difference score between the left hippocampus and left PrC volumes was the most powerful predictor of verbal episodic memory. Right hippocampal volume was not a significant predictor of nonverbal episodic memory. Verbal and nonverbal semantic memory were not significantly predicted by any combination of rhinal cortex structures. This quantitative study suggests a lateralized or material-specific memory function for the left hippocampus and left PrC, in contrast to the bilateral role of the ErC. The left hippocampus and left PrC appear to act on verbal memory function through an opposing relationship. Finally, differentiation between hippocampal and subhippocampal components in terms of episodic and semantic memory, respectively, could not be supported by the current data.

An Exploratory Study of the Use of the Austin Maze in South Africa

A software version of the Austin Maze together with the Halstead-Reitan Category Test and Raven's Standard Progressive Matrices were administered to 30 students at the University of Venda, South Africa. For the entire sample, the average number of trials taken to reach criterion (that is, three consecutive error-free trials) on the Austin Maze was 19. The performance of male subjects was generally better than that of females. No significant correlations were found between performance on the Austin Maze and scores on the other psychometric tests. This is seen as implying that, for this group of subjects, the Austin Maze measures a different construct, as documented in the literature. The complexity of a contextual interpretation of the subjects poorer performance on the measures is discussed.

Interpreting ambiguous advertisements: the effect of frontal lobe damage

Despite intact primary language processes patients with frontal lobe deficits often have impaired communication skills including impaired capacity to understand conversational inference. This study examined the ability of three patients with demonstrated frontal lobe pathology to interpret lexically ambiguous advertisements. When compared to a nonbrain-damaged control group it was found that the frontal lobe patients were poorer at comprehending the abstract or inferred meanings inherent in the advertisements. The pattern of performance across the patients did, nevertheless, differ despite a similar end result. These findings are discussed in relation to theories concerning the contribution of the frontal lobes to language function.