Confabulation: damage to a specific inferior medial prefrontal system

Confabulation, the pathological production of false memories, occurs following a variety of aetiologies involving the frontal lobes, and is frequently held to be underpinned by combined memory and executive deficits. However, the critical frontal regions and specific cognitive deficits involved are unclear. Studies in amnesic patients have associated confabulation with damage to the orbital and ventromedial prefrontal cortex. However neuroimaging studies have associated memory control processes which are assumed to underlie confabulation with the right lateral prefrontal cortex. We used a confabulation battery to investigate the occurrence and localisation of confabulation in an unselected series of 38 patients with focal frontal lesions. 12 patients with posterior lesions and 50 healthy controls were included for comparison. Significantly higher levels of confabulation were found in the Frontal group, confirming previous reports. More detailed grouping according to lesion location within the frontal lobe revealed that patients with orbital, medial and left lateral damage confabulated in response to questions probing personal episodic memory. Patients with orbital, medial and right lateral damage confabulated in response to questions probing orientation to time. Performance-led analysis revealed that all patients who produced a total number of confabulations outside the normal range had a lesion affecting either the orbital region or inferior portion of the anterior cingulate. These data provide striking evidence that the critical deficit for confabulation has its anatomical location in the inferior medial frontal lobe. Performance on tests of memory and executive functioning showed considerable variability. Although a degree of memory impairment does seem necessary, performance on traditional executive tests is less helpful in explaining confabulation

The Prefrontal Cortex and Neurological Impairments of Active Thought

This article reviews the effects of lesions to the frontal cortex on the ability to carry out active thought, namely, to reason, think flexibly, produce strategies, and formulate and realize plans. We discuss how and why relevant neuropsychological studies should be carried out. The relationships between active thought and both intelligence and language are considered. The following basic processes necessary for effective active thought are reviewed: concentration, set switching, inhibiting potentiated responses, and monitoring and checking. Different forms of active thought are then addressed: abstraction, deduction, reasoning in well-structured and ill-structured problem spaces, novel strategy generation, and planning. We conclude that neuropsychological findings are valuable for providing information on systems rather than networks, especially information concerning prefrontal lateralization of function. We present a synthesis of the respective roles of the left and right lateral prefrontal cortex in active thought

Is the Brixton Spatial Anticipation Test sensitive to frontal dysfunction? Evidence from patients with frontal and posterior lesions

INTRODUCTION: The Brixton Spatial Anticipation Test is a widely used neuropsychological test, thought to assess executive functions and to be sensitive to frontal lobe lesions. Our aim was to investigate Brixton performance in patients with focal frontal or posterior lesions and healthy controls. METHOD: We compared performance on the Brixton in a sample of 24 frontal patients, 18 posterior patients and 22 healthy controls. Both overall performance (total number of errors) and error types were analyzed. RESULTS: We found no significant differences between frontal and posterior patients and healthy controls in overall Brixton performance. Moreover, our error analysis showed no difference between frontal patients, posterior patients and healthy controls. The only exception was that posterior patients had a greater tendency to guess and make more errors when following specific rules than healthy controls but this was no longer significant once fluid intelligence was controlled for. We also found no significant difference between the performance of patients with left lateral (n = 11), right lateral (n = 10) or superior medial (n = 18) frontal lesions and healthy controls. CONCLUSIONS: The Brixton test is not sensitive to frontal lobe dysfunction. It is likely that the test draws on a range of cognitive abilities not specific to frontal lobe lesions. Hence, caution should be taken when drawing conclusions about its neural substrates

Factors contributing to the distress, concerns, and needs of UK Neuroscience health care workers during the COVID-19 pandemic

COVID‐19 research from China suggests health care workers are at risk of distress, have specific concerns, and need support. It remains unknown whether findings are applicable to UK health care staff and whether psychological support based on generic approaches is effective. We administered an online survey at a leading neuroscience hospital in the UK to examine how individual staff characteristics contribute to distress, concerns, and interventions most valued during the COVID‐19 pandemic. We found a high incidence of distress, particularly in females and staff with previous mental health history. Concerns fell into three factors: ‘risk of infection’, ‘work challenges’, and ‘social change’, and were affected by professional role and contact with COVID‐19 patients. These three factors predicted distress. Psychological support and clear updates were deemed most useful, with specific needs affected by age, professional role, and contact with COVID‐19 patients. This is the first documentation of a high incidence of psychological distress predicted by three types of concerns in health care workers of a neuroscience hospital. Distress, concerns, and interventions most valued were all affected by individual staff characteristics. These findings highlight the importance of providing stratified, one to one support interventions, tailored to professional group, and background, rather than more generic approaches

Dyscalculia

The term dyscalculia refers to an acquired disorder of number processing and calculation skills following brain damage. Henschen was the first to identify this syndrome in 1919.1 However, for a long time dyscalculia was treated as one of the subcomponents of the Gerstmann syndrome or as an impairment due to more generalised cognitive deficits such as visuospatial and language disorders. It is now well established that impairments in number processing and calculation are independent from deficits in general intelligence, language, reading, writing, semantic memory and short-term memory.2 Acquired deficits in number processing and calculation are rather frequent after brain lesions and may result from both acute and neurodegenerative conditions. The incidence of dyscalculia in patients with either left hemisphere lesions or at the early stage of Alzheimer’s disease is high

Is the Weigl Colour-Form Sorting Test Specific to Frontal Lobe Damage?

OBJECTIVE: The Weigl Colour-Form Sorting Test is a brief, widely used test of executive function. So far, it is unknown whether this test is specific to frontal lobe damage. Our aim was to investigate Weigl performance in patients with focal, unilateral, left or right, frontal, or non-frontal lesions. METHOD: We retrospectively analysed data from patients with focal, unilateral, left or right, frontal (n = 37), or non-frontal (n = 46) lesions who had completed the Weigl. Pass/failure (two correct solutions/less than two correct solutions) and errors were analysed. RESULTS: A greater proportion of frontal patients failed the Weigl than non-frontal patients, which was highly significant (p < 0.001). In patients who failed the test, a significantly greater proportion of frontal patients provided the same solution twice. No significant differences in Weigl performance were found between patients with left versus right hemisphere lesions or left versus right frontal lesions. There was no significant correlation between performance on the Weigl and tests tapping fluid intelligence. CONCLUSIONS: The Weigl is specific to frontal lobe lesions and not underpinned by fluid intelligence. Both pass/failure on this test and error types are informative. Hence, the Weigl is suitable for assessing frontal lobe dysfunction

The neuropsychology needs of a hyper-acute stroke unit

BACKGROUND AND AIM: Guidelines recommend routine assessment and management of mood and cognition after stroke, but little is known about the value or feasibility of providing neuropsychology input during the hyper-acute period. We aimed to identify and describe the extent and nature of neuropsychological needs and to investigate the feasibility of providing direct neuropsychology input within a hyper-acute setting. METHODS: Over a 7-month period, Multidisciplinary Team (MDT) members of a central London Hyper-Acute Stroke Unit (HASU) identified stroke patients who they believed would benefit from neuropsychology input, and categorised the nature of neuropsychology intervention required. We examined the demographic and clinical characteristics of the patients identified and the type of intervention required. RESULTS: 23% of patients (101/448) were identified as requiring neuropsychology input. Patients deemed to require input were younger, more likely to be male and more functionally disabled than those not requiring input. Cognitive assessment was the main identified need (93%) followed by mood (29%) and family support (9%). 30% of patients required two types of intervention. During a pilot of neuropsychology provision, 17 patients were seen; 15 completed a full cognitive assessment. All patients assessed presented with cognitive impairment despite three being deemed cognitively intact (> standardised cut-off) using a cognitive screening tool. CONCLUSION: We showed that direct neuropsychology input on a HASU is necessary for complex and varied interventions involving cognition, mood and family support. Furthermore, input is feasible and useful in detecting cognitive impairment not revealed by screening instruments

Additional Queen Square (QS) screening items improve the test accuracy of the Montreal Cognitive Assessment (MoCA) after acute stroke

BACKGROUND The Montreal Cognitive Assessment (MoCA) is a popular cognitive screening tool used in stroke, but lacks sensitivity for detecting impairment in stroke-relevant domains of processing speed, non-verbal memory and executive functions. Our aim was to assess whether the test accuracy of the MoCA can be improved with additional tailored screening items targeting these three domains. METHODS We included 196 patients admitted to an acute stroke unit at the National Hospital for Neurology and Neurosurgery, Queen Square (QS), London. Participants completed the MoCA as well as a series of additional QS-screening items designed to assess speed of processing, non-verbal memory and executive functions. Performance on the MoCA and QS screening items was compared with performance on “gold standard” neuropsychological assessment. RESULTS In our sample, 22% of patients were classified as “cognitively intact” on the traditional MoCA alone (≥ 25). However, when tested on the QS-screening items, 40% of these patients failed on speed of processing, 56% failed on non-verbal memory and 26% failed on executive functions. Compared with neuropsychological assessment, the QS-screening items had good sensitivity (QS-Speed: 0.85; QS-Vis: 0.71; QS-EF: 0.73) and modest specificity (QS-Speed: 0.59; QS-Vis: 0.39; QS-EF: 0.54), regardless of stroke lateralisation. CONCLUSION Additional screening items detected impairments in speed of processing, non-verbal memory and executive functions over and above those captured using the standard MoCA. The use of these QS-screening items improves the detection of post-stroke cognitive deficits in domains not adequately covered by the standard MoCA