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  • Practical application of fundamental concepts in exercise physiology.

    24 October 2018

    The collection of primary data in laboratory classes enhances undergraduate practical and critical thinking skills. The present article describes the use of a lecture program, running in parallel with a series of linked practical classes, that emphasizes classical or standard concepts in exercise physiology. The academic and practical program ran under the title of a particular year II module named Sports Performance: Physiology and Assessment, and results are presented over a 3-yr period (2004-2006), based on an undergraduate population of 31 men and 34 women. The module compared laboratory-based indexes of endurance (e.g., ventilatory threshold and exercise economy) and high-intensity exercise (e.g., anaerobic power), respectively, with measures of human performance (based on 20-m shuttle run tests). The specific experimental protocols reinforced the lecture content to improve student understanding of the physiological and metabolic responses (and later adaptations) to exercise. In the present study, the strongest relationship with endurance performance was the treadmill velocity at maximal aerobic power (r = +0.88, P < 0.01, n = 51); in contrast, the strongest relationship with high-intensity exercise performance was the mean power output (in W/kg) measured during a 30-s all-out cycle ergometer sprint (r = +0.80, P < 0.01, n = 48). In class student data analysis improved undergraduate indepth or critical thinking during seminars and enhanced computer and data presentation skills. The endurance-based laboratories are particularly useful for examining the underlying scientific principles that determine aerobic performance but could equally well be adapted to investigate other topics, e.g., differences in the exercise response between men and women.

  • Cognitive motor interference while walking: a systematic review and meta-analysis.

    24 October 2018

    Dual-task methodology has been increasingly used to assess cognitive motor interference while walking. However, whether the observed dual-task-related gait changes are systematically related to methodological variations remains unclear and researchers still lack knowledge of what cognitive task to use in different groups for clinical purposes or for research. We systematically reviewed experimental studies that measured gait performance with and without performing concurrent cognitive task. Our results suggest that cognitive tasks that involve internal interfering factors seem to disturb gait performance more than those involving external interfering factors. Meta-analysis results show that the overall effect of different cognitive tasks was prominent in gait speed. In healthy participants, meta-regression analysis suggests strong associations between age and speed reduction under dual-task conditions and between the level of cognitive state and speed reduction under dual-task conditions. Standardizing research methodologies, as well as improving their ecological validity, enables better understanding of dual-task-related gait changes in different populations and improves, in turn, our understanding of neural mechanisms and gait control in general in content.

  • The Mini-Addenbrooke's Cognitive Examination: a new assessment tool for dementia.

    24 October 2018

    BACKGROUND/AIMS: We developed and validated the Mini-Addenbrooke's Cognitive Examination (M-ACE) in dementia patients. Comparisons were also made with the Mini Mental State Examination (MMSE). METHOD: The M-ACE was developed using Mokken scaling analysis in 117 dementia patients [behavioural variant frontotemporal dementia (bvFTD), n = 25; primary progressive aphasia (PPA), n = 49; Alzheimer's disease (AD), n = 34; corticobasal syndrome (CBS), n = 9] and validated in an independent sample of 164 dementia patients (bvFTD, n = 23; PPA, n = 82; AD, n = 38; CBS, n = 21) and 78 controls, who also completed the MMSE. RESULTS: The M-ACE consists of 5 items with a maximum score of 30. Two cut-offs were identified: (1) ≤25/30 has both high sensitivity and specificity, and (2) ≤21/30 is almost certainly a score to have come from a dementia patient regardless of the clinical setting. The M-ACE is more sensitive than the MMSE and is less likely to have ceiling effects. CONCLUSION: The M-ACE is a brief and sensitive cognitive screening tool for dementia. Two cut-offs (25 or 21) are recommended.

  • Transient epileptic amnesia: the contribution of the british neurological surveillance unit.

    24 October 2018

    Transient Epileptic Amnesia (TEA) is a subtype of temporal lobe epilepsy characterised by recurrent episodes of transient amnesia, usually in middle aged people, often occurring on waking, which prove to be due to epilepsy. Attacks are sometimes accompanied by other more familiar manifestations of epilepsy, especially olfactory hallucinations. The epilepsy typically responds very well to anticonvulsant treatment but interictal memory disturbance often persists despite abolition of the seizures, in particular an extensive autobiographical amnesia (AA), and a tendency for memories to fade more rapidly than usual over days to weeks (accelerated long-term forgetting, ALF). The TIME project (The Impairment of Memory in Epilepsy: see http://www.exeter.ac.uk/time/) was established in 2003 to study TEA and its associated interictal memory disturbance. It has since generated around 20 publications describing the clinical, neuropsychological and radiological features of TEA, AA and ALF.(1-4) The British Neurological Surveillance Unit (BNSU) contributed to patient recruitment in 2003-2005 and again recently (2011-present). In 2003-5, 32 patients were referred via the BNSU. 16 were included in the patient cohort described in our 2007 report,(1) nine were excluded as they did not satisfy our diagnostic criteria, seven were potentially suitable but study resources did not allow us to assess them fully. 22 cases have been referred recently. Details are awaited for 13, one refused consent, four have been assessed, three await assessment, one was excluded after assessment. The BNSU has made a major contribution to the success of the TIME project. The recruitment process would work more smoothly if participating neurologists i) asked patients for consent to pass on demographical and clinical details at the time of the clinic visit on which they are identified, ii) communicated these immediately to the researcher or iii) kept a note of patient details if i) and ii) are not feasible. The current system works well, and helps greatly in the recruitment of series of cases of moderately rare disorders, but its efficiency could be improved.

  • Sleep-dependent memory consolidation and accelerated forgetting.

    24 October 2018

    Accelerated long-term forgetting (ALF) is a form of memory impairment in which learning and initial retention of information appear normal but subsequent forgetting is excessively rapid. ALF is most commonly associated with epilepsy and, in particular, a form of late-onset epilepsy called transient epileptic amnesia (TEA). ALF provides a novel opportunity to investigate post-encoding memory processes, such as consolidation. Sleep is implicated in the consolidation of memory in healthy people and a deficit in sleep-dependent memory consolidation has been proposed as an explanation for ALF. If this proposal were correct, then sleep would not benefit memory retention in people with ALF as much as in healthy people, and ALF might only be apparent when the retention interval contains sleep. To test this theory, we compared performance on a sleep-sensitive memory task over a night of sleep and a day of wakefulness. We found, contrary to the hypothesis, that sleep benefits memory retention in TEA patients with ALF and that this benefit is no smaller in magnitude than that seen in healthy controls. Indeed, the patients performed significantly more poorly than the controls only in the wake condition and not the sleep condition. Patients were matched to controls on learning rate, initial retention, and the effect of time of day on cognitive performance. These results indicate that ALF is not caused by a disruption of sleep-dependent memory consolidation. Instead, ALF may be due to an encoding abnormality that goes undetected on behavioural assessments of learning, or by a deficit in memory consolidation processes that are not sleep-dependent.

  • Memory consolidation in aging and MCI after 1 week.

    24 October 2018

    OBJECTIVE: To assess consolidation in amnestic mild cognitive impairment (aMCI), controlling for differences in initial learning and using a protracted delay period for recall. METHOD: 15 individuals with aMCI were compared with 15 healthy older adult controls on a story learning task. Subjects were trained to criteria to equalize initial learning across subjects. Recall was tested at both the 30-min typically used delay and a 1-week delay used to target consolidation. RESULTS: Using repeated measures ANOVAs adjusted for age, we found group × time point interactions across the entire task between the final trial and 30-min delay, and again between the 30-min and 1-week delay periods, with aMCI having greater declines in recall as compared with controls. Significant group main effects were also found, with aMCI recalling less than controls. CONCLUSION: Consolidation was impaired in aMCI as compared with controls. Our findings indicate that aMCI-related performance typically measured at 30 min underestimates aMCI-associated memory deficits. This is the first study to isolate consolidation by controlling for initial learning differences and using a protracted delay period to target consolidation in an aMCI sample.

  • Accelerated long-term forgetting can become apparent within 3-8 hours of wakefulness in patients with transient epileptic amnesia.

    24 October 2018

    OBJECTIVE: Accelerated long-term forgetting (ALF) is typically defined as a memory disorder in which information that is learned and retained normally over standard intervals (∼30 min) is forgotten at an abnormally rapid rate thereafter. ALF has been reported, in particular, among patients with transient epileptic amnesia (TEA). Previous work in TEA has revealed ALF 24 hr - 1 week after initial memory acquisition. It is unclear, however, if ALF observed 24 hr after acquisition reflects (a) an impairment of sleep consolidation processes taking place during the first night's sleep, or (b) an impairment of daytime consolidation processes taking place during the day of acquisition. Here we focus on the daytime-forgetting hypothesis of ALF in TEA by tracking in detail the time course of ALF over the day of acquisition, as well as over 24 hr and 1 week. METHOD: Eleven TEA patients who showed ALF at 1 week and 16 matched controls learned 4 categorical word lists on the morning of the day of acquisition. We subsequently probed word-list retention 30 min, 3 hr, and 8 hr postacquisition (i.e., over the day of acquisition), as well as 24-hr and 1-week post acquisition. RESULTS: ALF became apparent in the TEA group over the course of the day of acquisition 3-8 hr after learning. No further forgetting was observed over the first night in either group. CONCLUSIONS: The results of this study show that ALF in TEA can result from a deficit in memory consolidation occurring within hours of learning without a requirement for intervening sleep.

  • Impaired picture recognition in transient epileptic amnesia.

    24 October 2018

    Transient epileptic amnesia (TEA) is an epileptic syndrome characterized by recurrent, brief episodes of amnesia. Transient epileptic amnesia is often associated with the rapid decline in recall of new information over hours to days (accelerated long-term forgetting - 'ALF'). It remains unknown how recognition memory is affected in TEA over time. Here, we report a systematic study of picture recognition in patients with TEA over the course of one week. Sixteen patients with TEA and 16 matched controls were presented with 300 photos of everyday life scenes. Yes/no picture recognition was tested 5min, 2.5h, 7.5h, 24h, and 1week after picture presentation using a subset of target pictures as well as similar and different foils. Picture recognition was impaired in the patient group at all test times, including the 5-minute test, but it declined normally over the course of 1week. This impairment was associated predominantly with an increased false alarm rate, especially for similar foils. High performance on a control test indicates that this impairment was not associated with perceptual or discrimination deficits. Our findings suggest that, at least in some TEA patients with ALF in verbal recall, picture recognition does not decline more rapidly than in controls over 1week. However, our findings of an early picture recognition deficit suggest that new visual memories are impoverished after minutes in TEA. This could be the result of deficient encoding or impaired early consolidation. The early picture recognition deficit observed could reflect either the early stages of the process that leads to ALF or a separable deficit of anterograde memory in TEA. Lastly, our study suggests that at least some patients with TEA are prone to falsely recognizing new everyday visual information that they have not in fact seen previously. This deficit, alongside their ALF in free recall, likely affects everyday memory performance.