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Mustile M, Kourtis D, Edwards MG, Ladouce S, Volpe D, Pilleri M, Pelosin E, Learmonth G, Donaldson DI, Ietswaart M. Characterizing neurocognitive impairments in Parkinson's disease with mobile EEG when walking and stepping over obstacles. Brain Commun 2023; 5:fcad326. [PMID: 38107501 PMCID: PMC10724048 DOI: 10.1093/braincomms/fcad326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 10/03/2023] [Accepted: 11/27/2023] [Indexed: 12/19/2023] Open
Abstract
The neural correlates that help us understand the challenges that Parkinson's patients face when negotiating their environment remain under-researched. This deficit in knowledge reflects the methodological constraints of traditional neuroimaging techniques, which include the need to remain still. As a result, much of our understanding of motor disorders is still based on animal models. Daily life challenges such as tripping and falling over obstacles represent one of the main causes of hospitalization for individuals with Parkinson's disease. Here, we report the neural correlates of naturalistic ambulatory obstacle avoidance in Parkinson's disease patients using mobile EEG. We examined 14 medicated patients with Parkinson's disease and 17 neurotypical control participants. Brain activity was recorded while participants walked freely, and while they walked and adjusted their gait to step over expected obstacles (preset adjustment) or unexpected obstacles (online adjustment) displayed on the floor. EEG analysis revealed attenuated cortical activity in Parkinson's patients compared to neurotypical participants in theta (4-7 Hz) and beta (13-35 Hz) frequency bands. The theta power increase when planning an online adjustment to step over unexpected obstacles was reduced in Parkinson's patients compared to neurotypical participants, indicating impaired proactive cognitive control of walking that updates the online action plan when unexpected changes occur in the environment. Impaired action planning processes were further evident in Parkinson's disease patients' diminished beta power suppression when preparing motor adaptation to step over obstacles, regardless of the expectation manipulation, compared to when walking freely. In addition, deficits in reactive control mechanisms in Parkinson's disease compared to neurotypical participants were evident from an attenuated beta rebound signal after crossing an obstacle. Reduced modulation in the theta frequency band in the resetting phase across conditions also suggests a deficit in the evaluation of action outcomes in Parkinson's disease. Taken together, the neural markers of cognitive control of walking observed in Parkinson's disease reveal a pervasive deficit of motor-cognitive control, involving impairments in the proactive and reactive strategies used to avoid obstacles while walking. As such, this study identified neural markers of the motor deficits in Parkinson's disease and revealed patients' difficulties in adapting movements both before and after avoiding obstacles in their path.
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Affiliation(s)
- Magda Mustile
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
- The Psychological Sciences Research Institute, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
| | - Dimitrios Kourtis
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Martin G Edwards
- The Psychological Sciences Research Institute, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
| | - Simon Ladouce
- Department of Brain and Cognition, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Daniele Volpe
- Fresco Parkinson Center, Villa Margherita, S. Stefano Riabilitazione, 36100 Vicenza, Italy
| | - Manuela Pilleri
- Fresco Parkinson Center, Villa Margherita, S. Stefano Riabilitazione, 36100 Vicenza, Italy
| | - Elisa Pelosin
- Ospedale Policlinico San Martino, IRCCS, 16132 Genova, Italy
| | - Gemma Learmonth
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, G12 8QQ, UK
| | - David I Donaldson
- School of Psychology and Neuroscience, University of St Andrews, St. Andrews, KY16 9AJ, UK
| | - Magdalena Ietswaart
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
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2
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Turner C, Baylan S, Bracco M, Cruz G, Hanzal S, Keime M, Kuye I, McNeill D, Ng Z, van der Plas M, Ruzzoli M, Thut G, Trajkovic J, Veniero D, Wale SP, Whear S, Learmonth G. Developmental changes in individual alpha frequency: Recording EEG data during public engagement events. Imaging Neurosci (Camb) 2023; 1:1-14. [PMID: 37719836 PMCID: PMC10503479 DOI: 10.1162/imag_a_00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/05/2023] [Accepted: 06/05/2023] [Indexed: 09/19/2023]
Abstract
Statistical power in cognitive neuroimaging experiments is often very low. Low sample size can reduce the likelihood of detecting real effects (false negatives) and increase the risk of detecting non-existing effects by chance (false positives). Here, we document our experience of leveraging a relatively unexplored method of collecting a large sample size for simple electroencephalography (EEG) studies: by recording EEG in the community during public engagement and outreach events. We collected data from 346 participants (189 females, age range 6-76 years) over 6 days, totalling 29 hours, at local science festivals. Alpha activity (6-15 Hz) was filtered from 30 seconds of signal, recorded from a single electrode placed between the occipital midline (Oz) and inion (Iz) while the participants rested with their eyes closed. A total of 289 good-quality datasets were obtained. Using this community-based approach, we were able to replicate controlled, lab-based findings: individual alpha frequency (IAF) increased during childhood, reaching a peak frequency of 10.28 Hz at 28.1 years old, and slowed again in middle and older age. Total alpha power decreased linearly, but the aperiodic-adjusted alpha power did not change over the lifespan. Aperiodic slopes and intercepts were highest in the youngest participants. There were no associations between these EEG indexes and self-reported fatigue, measured by the Multidimensional Fatigue Inventory. Finally, we present a set of important considerations for researchers who wish to collect EEG data within public engagement and outreach environments.
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Affiliation(s)
- Christopher Turner
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Satu Baylan
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Martina Bracco
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Gabriela Cruz
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Simon Hanzal
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Marine Keime
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Isaac Kuye
- School of Molecular Biosciences, University of Glasgow, Glasgow, Scotland
| | - Deborah McNeill
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, Scotland
| | - Zika Ng
- School of Molecular Biosciences, University of Glasgow, Glasgow, Scotland
| | - Mircea van der Plas
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Manuela Ruzzoli
- Basque Center on Cognition Brain and Language (BCBL), Donostia/San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Gregor Thut
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Jelena Trajkovic
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Domenica Veniero
- School of Psychology, University of Nottingham, Nottingham, United Kingdom
| | - Sarah P. Wale
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Sarah Whear
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Gemma Learmonth
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
- Division of Psychology, University of Stirling, Stirling, Scotland
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3
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Kaul D, Papadatou-Pastou M, Learmonth G. A meta-analysis of the line bisection task in children. Laterality 2023; 28:48-71. [PMID: 36416485 DOI: 10.1080/1357650x.2022.2147941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Meta-analyses have shown subtle, group-level asymmetries of spatial attention in adults favouring the left hemispace (pseudoneglect). However, no meta-analysis has synthesized data on children. We performed a random-effects meta-analysis of spatial biases in children aged ≤16 years. Databases (PsycINFO, Web of Science & Scopus) and pre-print servers (bioRxiv, medRxiv & PsyArXiv) were searched for studies involving typically developing children with a mean age of ≤16, who were tested using line bisection. Thirty-three datasets, from 31 studies, involving 2101 children, were included. No bias was identified overall, but there was a small leftward bias in a subgroup where all children were aged ≤16. Moderator analysis found symmetrical neglect, with right-handed actions resulting in right-biased bisections, and left-handed actions in left-biased bisections. Bisections were more leftward in studies with a higher percentage of boys relative to girls. Mean age, hand preference, and control group status did not moderate biases, and there was no difference between children aged ≤7 and ≥7 years, although the number of studies in each moderator analysis was small. There was no evidence of small study bias. We conclude that pseudoneglect may be present in children but is dependent on individual characteristics (sex) and/or task demands (hand used).Registration: Open Science Framework (https://osf.io/n68fz/).
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Affiliation(s)
- Danishta Kaul
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
| | - Marietta Papadatou-Pastou
- School of Education, National and Kapodistrian University of Athens, Athens, Greece.,Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Gemma Learmonth
- School of Psychology & Neuroscience, University of Glasgow, Glasgow, Scotland
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4
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Learmonth G, Papadatou-Pastou M. A Meta-Analysis of Line Bisection and Landmark Task Performance in Older Adults. Neuropsychol Rev 2021; 32:438-457. [PMID: 33890188 PMCID: PMC9090707 DOI: 10.1007/s11065-021-09505-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 04/05/2021] [Indexed: 11/28/2022]
Abstract
Young adults exhibit a small asymmetry of visuospatial attention that favours the left side of space relative to the right (pseudoneglect). However, it remains unclear whether this leftward bias is maintained, eliminated or shifted rightward in older age. Here we present two meta-analyses that aimed to identify whether adults aged ≥50 years old display a group-level spatial attention bias, as indexed by the line bisection and the landmark tasks. A total of 69 datasets from 65 studies, involving 1654 participants, were analysed. In the meta-analysis of the line bisection task (n = 63), no bias was identified for studies where the mean age was ≥50, but there was a clear leftward bias in a subset where all individual participants were aged ≥50. There was no moderating effect of the participant’s age or sex, line length, line position, nor the presence of left or right cues. There was a small publication bias in favour of reporting rightward biases. Of note, biases were slightly more leftward in studies where participants had been recruited as part of a stand-alone older group, compared to studies where participants were recruited as controls for a clinical study. Similarly, no spatial bias was observed in the meta-analysis of the landmark task, although the number of studies included was small (n = 6). Overall, these results indicate that over 50s maintain a group-level leftward bias on the line bisection task, but more studies are needed to determine whether this bias can be modulated by stimulus- or state-dependent factors.
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Affiliation(s)
- Gemma Learmonth
- Institute of Neuroscience & Psychology, University of Glasgow, Glasgow, Scotland.
| | - Marietta Papadatou-Pastou
- School of Education, National and Kapodistrian University of Athens, Athens, Greece.,Biomedical Research Foundation, Academy of Athens, Athens, Greece
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5
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Abstract
It is clear already that in current and future years more people will suffer from stroke, whether related to COVID-19 or not, and given its prevalence, many more people's lives will be affected by neglect. Here we hope to have contributed to its possible amelioration with highlights of the latest thinking on neglect diagnosis, prevalence and treatment.
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Affiliation(s)
- Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, UK
| | - Gemma Learmonth
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | | | - Peii Chen
- Kessler Foundation, West Orange, NJ, USA.,Department of Physical Medicine and Rehabilitation, Rutgers University, New Brunswick, NJ, USA
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6
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Mustile M, Kourtis D, Ladouce S, Learmonth G, Edwards MG, Donaldson DI, Ietswaart M. Mobile EEG reveals functionally dissociable dynamic processes supporting real-world ambulatory obstacle avoidance: Evidence for early proactive control. Eur J Neurosci 2021; 54:8106-8119. [PMID: 33465827 DOI: 10.1111/ejn.15120] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 12/07/2020] [Accepted: 12/28/2020] [Indexed: 11/29/2022]
Abstract
The ability to safely negotiate the world on foot takes humans years to develop, reflecting the extensive cognitive demands associated with real-time planning and control of walking. Despite the importance of walking, methodological limitations mean that surprisingly little is known about the neural and cognitive processes that support ambulatory motor control. Here, we report mobile EEG data recorded from 32 healthy young adults during real-world ambulatory obstacle avoidance. Participants walked along a path while stepping over expected and unexpected obstacles projected on the floor, allowing us to capture the dynamic oscillatory response to changes in environmental demands. Compared to obstacle-free walking, time-frequency analysis of the EEG data revealed clear neural markers of proactive and reactive forms of movement control (occurring before and after crossing an obstacle), visible as increases in frontal theta and centro-parietal beta power respectively. Critically, the temporal profile of changes in frontal theta allowed us to arbitrate between early selection and late adaptation mechanisms of proactive control. Our data show that motor plans are updated as soon as an upcoming obstacle appears, rather than when the obstacle is reached. In addition, regardless of whether motor plans required updating, a clear beta rebound was present after obstacles were crossed, reflecting the resetting of the motor system. Overall, mobile EEG recorded during real-world walking provides novel insight into the cognitive and neural basis of dynamic motor control in humans, suggesting new routes to the monitoring and rehabilitation of motor disorders such as dyspraxia and Parkinson's disease.
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Affiliation(s)
- Magda Mustile
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Dimitrios Kourtis
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Simon Ladouce
- Institut Supérieur de l'Aéronautique et de l'Espace (ISAE), Toulouse, France
| | - Gemma Learmonth
- Institute of Neuroscience & Psychology, University of Glasgow, Glasgow, UK
| | - Martin G Edwards
- Institute of Research in the Psychological Sciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - David I Donaldson
- School of Psychology and Neuroscience, University of St Andrews, St. Andrews, UK
| | - Magdalena Ietswaart
- Psychology, Faculty of Natural Sciences, University of Stirling, Stirling, UK
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7
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Turner C, Jackson C, Learmonth G. Is the "end-of-study guess" a valid measure of sham blinding during transcranial direct current stimulation? Eur J Neurosci 2020; 53:1592-1604. [PMID: 33098709 PMCID: PMC8048983 DOI: 10.1111/ejn.15018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/30/2020] [Accepted: 10/16/2020] [Indexed: 11/28/2022]
Abstract
Studies using transcranial direct current stimulation (tDCS) typically incorporate a fade‐in, short‐stimulation, fade‐out sham (placebo) protocol, which is assumed to be indistinct from a 10–30 min active protocol on the scalp. However, many studies report that participants can dissociate active stimulation from sham, even during low‐intensity 1 mA currents. We recently identified differences in the perception of an active (10 min of 1 mA) and a sham (20 s of 1 mA) protocol that lasted for 5 min after the cessation of sham. In the present study we assessed whether delivery of a higher‐intensity 2 mA current would exacerbate these differences. Two protocols were delivered to 32 adults in a double‐blinded, within‐subjects design (active: 10 min of 2 mA, and sham: 20 s of 2 mA), with the anode over the left primary motor cortex and the cathode on the right forehead. Participants were asked “Is the stimulation on?” and “How sure are you?” at 30 s intervals during and after stimulation. The differences between active and sham were more consistent and sustained during 2 mA than during 1 mA. We then quantified how well participants were able to track the presence and absence of stimulation (i.e. their sensitivity) during the experiment using cross‐correlations. Current strength was a good classifier of sensitivity during active tDCS, but exhibited only moderate specificity during sham. The accuracy of the end‐of‐study guess was no better than chance at predicting sensitivity. Our results indicate that the traditional end‐of‐study guess poorly reflects the sensitivity of participants to stimulation, and may not be a valid method of assessing sham blinding.
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Affiliation(s)
| | | | - Gemma Learmonth
- School of Psychology, University of Glasgow, Glasgow, UK.,Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
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8
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Learmonth G, Benwell CSY, Märker G, Dascalu D, Checketts M, Santosh C, Barber M, Walters M, Muir KW, Harvey M. Non-invasive brain stimulation in Stroke patients (NIBS): A prospective randomized open blinded end-point (PROBE) feasibility trial using transcranial direct current stimulation (tDCS) in post-stroke hemispatial neglect. Neuropsychol Rehabil 2020; 31:1163-1189. [PMID: 32498606 PMCID: PMC8372288 DOI: 10.1080/09602011.2020.1767161] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Up to 80% of people who experience a right-hemisphere stroke suffer from hemispatial neglect. This syndrome is debilitating and impedes rehabilitation. We carried out a clinical feasibility trial of transcranial direct current stimulation (tDCS) and a behavioural rehabilitation programme, alone or in combination, in patients with neglect. Patients >4 weeks post right hemisphere stroke were randomized to 10 sessions of tDCS, 10 sessions of a behavioural intervention, combined intervention, or a control task. Primary outcomes were recruitment and retention rates, with secondary outcomes effect sizes on measures of neglect and quality of life, assessed directly after the interventions, and at 6 months follow up. Of 288 confirmed stroke cases referred (representing 7% of confirmed strokes), we randomized 8% (0.6% of stroke cases overall). The largest number of exclusions (91/288 (34%)) were due to medical comorbidities that prevented patients from undergoing 10 intervention sessions. We recruited 24 patients over 29 months, with 87% completing immediate post-intervention and 67% 6 month evaluations. We established poor feasibility of a clinical trial requiring repeated hospital-based tDCS within a UK hospital healthcare setting, either with or without behavioural training, over a sustained time period. Future trials should consider intensity, duration and location of tDCS neglect interventions.Trial registration: ClinicalTrials.gov identifier: NCT02401724.
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Affiliation(s)
- Gemma Learmonth
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.,School of Psychology, University of Glasgow, Glasgow, UK
| | - Christopher S Y Benwell
- School of Psychology, University of Glasgow, Glasgow, UK.,Division of Psychology, School of Social Sciences, University of Dundee, Dundee, UK
| | - Gesine Märker
- School of Psychology, University of Glasgow, Glasgow, UK
| | - Diana Dascalu
- School of Psychology, University of Glasgow, Glasgow, UK
| | - Matthew Checketts
- School of Psychology, University of Glasgow, Glasgow, UK.,Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK
| | | | - Mark Barber
- University Hospital Monklands, Lanarkshire, UK
| | - Matthew Walters
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Keith W Muir
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, UK
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9
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Greinacher R, Buhôt L, Möller L, Learmonth G. The time course of ineffective sham-blinding during low-intensity (1 mA) transcranial direct current stimulation. Eur J Neurosci 2019; 50:3380-3388. [PMID: 31228880 PMCID: PMC6899874 DOI: 10.1111/ejn.14497] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 06/10/2019] [Accepted: 06/17/2019] [Indexed: 11/27/2022]
Abstract
Studies using transcranial direct current stimulation (tDCS) typically compare an active protocol relative to a shorter sham (placebo) protocol. Both protocols are presumed to be perceptually identical on the scalp, and thus represent an effective method of delivering double-blinded experimental designs. However, participants often show above-chance accuracy when asked which condition involved active/sham retrospectively. We assessed the time course of sham-blinding during active and sham tDCS. We predicted that participants would be aware that the current is switched on for longer in the active versus sham protocol. Thirty-two adults were tested in a preregistered, double-blinded, within-subjects design. A forced-choice reaction time task was undertaken before, during and after active (10 min 1 mA) and sham (20 s 1 mA) tDCS. The anode was placed over the left primary motor cortex (C3) to target the right hand, and the cathode on the right forehead. Two probe questions were asked every 30 s: "Is the stimulation on?" and "How sure are you?". Distinct periods of non-overlapping confidence intervals were identified between conditions, totalling 5 min (57.1% of the total difference in stimulation time). These began immediately after sham ramp-down and lasted until the active protocol had ended. We therefore show a failure of placebo control during 1 mA tDCS. These results highlight the need to develop more effective methods of sham-blinding during transcranial electrical stimulation protocols, even when delivered at low-intensity current strengths.
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Affiliation(s)
- Robert Greinacher
- School of PsychologyUniversity of GlasgowGlasgowUK
- Quality and Usability LabTechnische Universität BerlinBerlinGermany
| | | | - Lisa Möller
- School of PsychologyUniversity of GlasgowGlasgowUK
- Department of NeurologyUniversity of LübeckLübeckGermany
| | - Gemma Learmonth
- School of PsychologyUniversity of GlasgowGlasgowUK
- Centre for Cognitive NeuroimagingInstitute of Neuroscience and PsychologyUniversity of GlasgowGlasgowUK
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10
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Learmonth G, Buhôt L, Möller L, Greinacher R. Ineffective single-blinding during 1mA transcranial direct current stimulation. J Vis 2019. [DOI: 10.1167/19.10.277c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Gemma Learmonth
- School of Psychology, University of Glasgow, Glasgow, Scotland
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, Scotland
| | - Larissa Buhôt
- School of Psychology, University of Glasgow, Glasgow, Scotland
| | - Lisa Möller
- School of Psychology, University of Glasgow, Glasgow, Scotland
- Department of Neurology, University of Lübeck, Lübeck, Germany
| | - Robert Greinacher
- School of Psychology, University of Glasgow, Glasgow, Scotland
- Quality and Usability Lab, Technische Universität Berlin, Berlin, Germany
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11
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Learmonth G, Felisatti F, Siriwardena N, Checketts M, Benwell CSY, Märker G, Thut G, Harvey M. No Interaction between tDCS Current Strength and Baseline Performance: A Conceptual Replication. Front Neurosci 2017; 11:664. [PMID: 29249932 PMCID: PMC5717015 DOI: 10.3389/fnins.2017.00664] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/15/2017] [Indexed: 01/05/2023] Open
Abstract
Several recent studies have reported non-linear effects of transcranial direct current stimulation (tDCS), which has been attributed to an interaction between the stimulation parameters (e.g., current strength, duration) and the neural state of the cortex being stimulated (e.g., indexed by baseline performance ability, age) (see Fertonani and Miniussi, 2016). We have recently described one such non-linear interaction between current strength and baseline performance on a visuospatial attention (landmark) task (Benwell et al., 2015). In this previous study, we induced a small overall rightward shift of spatial attention across 38 participants using bi-hemispheric tDCS applied for 20 min (concurrent left posterior parietal (P5) anode and right posterior parietal (P6) cathode) relative to a sham protocol. Importantly, this shift in bias was driven by a state-dependent interaction between current intensity and the discrimination sensitivity of the participant at baseline (pre-stimulation) for the landmark task. Individuals with high discrimination sensitivity (HDS) shifted rightward in response to low- (1 mA) but not high-intensity (2 mA) tDCS, whereas individuals with low discrimination sensitivity (LDS) shifted rightward with high- but not low-intensity stimulation. However, in Benwell et al. (2015) current strength was applied as a between-groups factor, where half of the participants received 1 mA and half received 2 mA tDCS, thus we were unable to compare high and low-intensity tDCS directly within each individual. Here we aimed to replicate these findings using a within-group design. Thirty young adults received 15 min of 1 and 2 mA tDCS, and a sham protocol, each on different days, to test the concept of an interaction between baseline performance and current strength. We found no overall rightward shift of spatial attention with either current strength, and no interaction between performance and current strength. These results provide further evidence of low replicability of non-invasive brain stimulation protocols, and the need for further attempts to replicate the key experimental findings within this field.
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Affiliation(s)
- Gemma Learmonth
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Matthew Checketts
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Gesine Märker
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.,School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
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12
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Learmonth G, Benwell CS, Thut G, Harvey M. Age-related reduction of hemispheric lateralisation for spatial attention: An EEG study. Neuroimage 2017; 153:139-151. [DOI: 10.1016/j.neuroimage.2017.03.050] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 03/16/2017] [Accepted: 03/19/2017] [Indexed: 11/25/2022] Open
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13
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Rossit S, Benwell CSY, Szymanek L, Learmonth G, McKernan-Ward L, Corrigan E, Muir K, Reeves I, Duncan G, Birschel P, Roberts M, Livingstone K, Jackson H, Castle P, Harvey M. Efficacy of home-based visuomotor feedback training in stroke patients with chronic hemispatial neglect. Neuropsychol Rehabil 2017; 29:251-272. [DOI: 10.1080/09602011.2016.1273119] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | | | | | | | - Laura McKernan-Ward
- School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | | | - Keith Muir
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Ian Reeves
- Department of Medicine for the Elderly, Southern General Hospital, Glasgow, UK
| | - George Duncan
- Department of Medicine for the Elderly, Southern General Hospital, Glasgow, UK
| | - Philip Birschel
- Department of Medicine for the Elderly, Southern General Hospital, Glasgow, UK
| | - Margaret Roberts
- Department of Medicine for the Elderly, Southern General Hospital, Glasgow, UK
| | - Katrina Livingstone
- Stroke Discharge and Rehabilitation Team, Southern General Hospital, Glasgow, UK
| | - Hazel Jackson
- Stroke Discharge and Rehabilitation Team, Southern General Hospital, Glasgow, UK
| | | | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, UK
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14
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Learmonth G, Harvey M. Age-related changes in the hemispheric lateralisation of pre-stimulus alpha. J Vis 2016. [DOI: 10.1167/16.12.1270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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15
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Learmonth G, Gallagher A, Gibson J, Thut G, Harvey M. Intra- and Inter-Task Reliability of Spatial Attention Measures in Pseudoneglect. PLoS One 2015; 10:e0138379. [PMID: 26378925 PMCID: PMC4574708 DOI: 10.1371/journal.pone.0138379] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/28/2015] [Indexed: 11/18/2022] Open
Abstract
Healthy young adults display a leftward asymmetry of spatial attention ("pseudoneglect") that has been measured with a wide range of different tasks. Yet at present there is a lack of systematic evidence that the tasks commonly used in research today are i) stable measures over time and ii) provide similar measures of spatial bias. Fifty right-handed young adults were tested on five tasks (manual line bisection, landmark, greyscales, gratingscales and lateralised visual detection) on two different days. All five tasks were found to be stable measures of bias over the two testing sessions, indicating that each is a reliable measure in itself. Surprisingly, no strongly significant inter-task correlations were found. However, principal component analysis revealed left-right asymmetries to be subdivided in 4 main components, namely asymmetries in size judgements (manual line bisection and landmark), luminance judgements (greyscales), stimulus detection (lateralised visual detection) and judgements of global/local features (manual line bisection and grating scales). The results align with recent research on hemispatial neglect which conceptualises the condition as multi-component rather than a single pathological deficit of spatial attention. We conclude that spatial biases in judgment of visual stimulus features in healthy adults (e.g., pseudoneglect) is also a multi-component phenomenon that may be captured by variations in task demands which engage task-dependent patterns of activation within the attention network.
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Affiliation(s)
- Gemma Learmonth
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
| | - Aodhan Gallagher
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Jamie Gibson
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, United Kingdom
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16
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Benwell CSY, Learmonth G, Miniussi C, Harvey M, Thut G. Non-linear effects of transcranial direct current stimulation as a function of individual baseline performance: Evidence from biparietal tDCS influence on lateralized attention bias. Cortex 2015; 69:152-65. [PMID: 26073146 DOI: 10.1016/j.cortex.2015.05.007] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 03/12/2015] [Accepted: 05/08/2015] [Indexed: 12/13/2022]
Abstract
Transcranial direct current stimulation (tDCS) is a well-established technique for non-invasive brain stimulation (NIBS). However, the technique suffers from a high variability in outcome, some of which is likely explained by the state of the brain at tDCS-delivery but for which explanatory, mechanistic models are lacking. Here, we tested the effects of bi-parietal tDCS on perceptual line bisection as a function of tDCS current strength (1 mA vs 2 mA) and individual baseline discrimination sensitivity (a measure associated with intrinsic uncertainty/signal-to-noise balance). Our main findings were threefold. We replicated a previous finding (Giglia et al., 2011) of a rightward shift in subjective midpoint after Left anode/Right cathode tDCS over parietal cortex (sham-controlled). We found this effect to be weak over our entire sample (n = 38), but to be substantial in a subset of participants when they were split according to tDCS-intensity and baseline performance. This was due to a complex, nonlinear interaction between these two factors. Our data lend further support to the notion of state-dependency in NIBS which suggests outcome to depend on the endogenous balance between task-informative 'signal' and task-uninformative 'noise' at baseline. The results highlight the strong influence of individual differences and variations in experimental parameters on tDCS outcome, and the importance of fostering knowledge on the factors influencing tDCS outcome across cognitive domains.
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Affiliation(s)
- Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK; School of Psychology, University of Glasgow, Glasgow, UK.
| | - Gemma Learmonth
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK; School of Psychology, University of Glasgow, Glasgow, UK
| | - Carlo Miniussi
- Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, UK
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
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17
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Learmonth G, Thut G, Benwell CSY, Harvey M. The implications of state-dependent tDCS effects in aging: Behavioural response is determined by baseline performance. Neuropsychologia 2015; 74:108-19. [PMID: 25637226 DOI: 10.1016/j.neuropsychologia.2015.01.037] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/19/2015] [Accepted: 01/26/2015] [Indexed: 01/17/2023]
Abstract
Young adults typically display a processing advantage towards the left side of space ("pseudoneglect"), possibly as a result of right parietal dominance for spatial attention. This bias is ameliorated with age, with older adults displaying either no strongly lateralised bias, or a slight bias towards the right. This may represent an age-related reduction of right hemispheric dominance and/or increased left hemispheric involvement. Here, we applied anodal transcranial direct current stimulation (atDCS) to the right posterior parietal cortex (PPC; R-atDCS), the left PPC (L-atDCS) and a Sham protocol in young and older adults during a titrated lateralised visual detection task. We aimed to facilitate visual detection sensitivity in the contralateral visual field with both R-atDCS and L-atDCS relative to Sham. We found no differences in the effects of stimulation between young and older adults. Instead the effects of atDCS were state-dependent (i.e. related to task performance at baseline). Relative to Sham, poor task performers were impaired in both visual fields by anodal stimulation of the left posterior parietal cortex (PPC). Conversely, good performers maintained sensitivity in both visual fields in response to R-atDCS, although this effect was small. We highlight the importance of considering baseline task ability when designing tDCS experiments, particularly in older adults.
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Affiliation(s)
- Gemma Learmonth
- Centre for Cognitive Neuroimaging, School of Psychology, University of Glasgow, Glasgow G12 8QB, UK; School of Psychology, University of Glasgow, Glasgow G12 8QB, UK.
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, School of Psychology, University of Glasgow, Glasgow G12 8QB, UK
| | - Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, School of Psychology, University of Glasgow, Glasgow G12 8QB, UK; School of Psychology, University of Glasgow, Glasgow G12 8QB, UK
| | - Monika Harvey
- School of Psychology, University of Glasgow, Glasgow G12 8QB, UK
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18
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Benwell C, Learmonth G, Harvey M, Thut G. P267: The effects of bilateral transcranial direct current stimulation over posterior parietal cortices on visuospatial attention bias. Clin Neurophysiol 2014. [DOI: 10.1016/s1388-2457(14)50388-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Benwell CSY, Thut G, Learmonth G, Harvey M. Spatial attention: differential shifts in pseudoneglect direction with time-on-task and initial bias support the idea of observer subtypes. Neuropsychologia 2013; 51:2747-56. [PMID: 24076376 DOI: 10.1016/j.neuropsychologia.2013.09.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/18/2013] [Indexed: 11/17/2022]
Abstract
Asymmetry in human spatial attention has long been documented. In the general population the majority of individuals tend to misbisect horizontal lines to the left of veridical centre. Nonetheless in virtually all previously reported studies on healthy participants, there have been subsets of people displaying rightward biases. In this study, we report differential time-on task effects depending on participants' initial pseudoneglect bias: participants with an initial left bias in a landmark task (in which they had to judge whether a transection mark appeared closer to the right or left end of a line) showed a significant rightward shift over the course of the experimental session, whereas participants with an initial right bias shifted leftwards. We argue that these differences in initial biases as well as the differential shifts with time-on task reflect genuine observer subtypes displaying diverging behavioural patterns. These observer subtypes could be driven by differences in brain organisation and/or lateralisation such as varying anatomical pathway asymmetries (Thiebaut de Schotten et al., 2011).
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Affiliation(s)
- Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow 58 Hillhead Street, G12 8QB, United Kingdom; School of Psychology, University of Glasgow, Glasgow G12 8QB, United Kingdom
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20
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Harvey M, Muir K, Reeves I, Duncan G, Birschel P, Roberts M, Livingstone K, Jackson H, Hogg C, Castle P, Learmonth G, Rossit S. Long term improvements in activities of daily living in patients with hemispatial neglect. Behav Neurol 2011; 23:237-9. [PMID: 21422564 PMCID: PMC5434380 DOI: 10.3233/ben-2010-0304] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Monika Harvey
- School of Psychology, University of Glasgow, Glasgow, Scotland, UK.
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21
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Rossit S, Malhotra P, Muir K, Reeves I, Duncan G, Livingstone K, Jackson H, Hogg C, Castle P, Learmonth G, Harvey M. No Neglect-Specific Deficits in Reaching Tasks. Cereb Cortex 2009; 19:2616-24. [DOI: 10.1093/cercor/bhp016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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22
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Venter FS, Learmonth G. Esophageal squamous metaplasia: nudging the esophageal carcinoma morphogenetic paradigm. Med Hypotheses 2002; 58:270-5. [PMID: 12027518 DOI: 10.1054/mehy.2001.1521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The concept regarding esophageal squamous metaplasia, its existence, origin and the role it plays in the etiology of esophageal carcinoma, needs some urgent attention. Explanations regarding the presence of metaplastic squamous epithelial cells on esophageal smears, from asymptomatic high-risk patients undergoing screening for esophageal carcinoma, are difficult to find. The presence of squamous metaplastic cells on smears from the esophagus collected by us since 1983, from rural Transkei populations, is a regular finding and warrants some discussion. Cellular material from the esophageal lumen is collected with a gelatine encapsulated sponge brush for cytological evaluation. Each full-length, 'blind' sampling procedure produces a mixture of single cells, sheets, small groups as well as microbiopsies. Some very well preserved and excellent examples of esophageal epithelium undergoing or in a state of squamous metaplasia are a regular find.
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Affiliation(s)
- F S Venter
- PROMEC Unit, Medical Research Council, Tygerberg, South Africa.
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23
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Veropoulos K, Learmonth G, Campbell C, Knight B, Simpson J. Automated identification of tubercle bacilli in sputum. A preliminary investigation. Anal Quant Cytol Histol 1999; 21:277-82. [PMID: 10560504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
OBJECTIVE To use an automated method to detect tubercle bacilli in sputum specimens. STUDY DESIGN Using fluorescence microscopy, tubercle bacilli were identified on auramine-stained sputum specimens. Images were then captured with a digital camera and enhanced through imaging processing techniques. The bacilli were recognized using neural network classifiers. RESULTS This preliminary investigation demonstrated a sensitivity of 94.1% for the identification of individual bacilli. As there are usually fairly numerous tubercle bacilli in the sputum of patients with active pulmonary tuberculosis, the overall diagnostic accuracy of sputum smear-positive patients can be expected to be very high. CONCLUSION Potential benefits of automated screening for TB bacilli are: rapid, accurate, inexpensive diagnosis; the ability to screen larger numbers of people; increased resources to monitor patients; and reduction in health risks to staff.
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Affiliation(s)
- K Veropoulos
- Advanced Computing Research Center, University of Bristol, United Kingdom.
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van Wyk WF, Dent DM, Hacking EA, Learmonth G, Kottler RE, Gudgeon CA, Tiltman A. Combined assessment (aspiration cytology and mammography) of clinically suspicious breast masses. S Afr Med J 1995; 85:81-4. [PMID: 7597539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We examined the safety and utility of the combined assessment of aspiration cytology and mammography in 705 women who had clinically suspicious or malignant palpable breast masses. Histological assessment confirmed 176 benign and 529 malignant lesions. There were no incorrect (false positive) diagnoses made in the 176 benign masses when combined assessment was used (specificity 1.0; predictive value 0.86); in isolation, however, there was a false positive cytological diagnosis ('papillary carcinoma') and 3 false positive mammographic diagnoses. Benign disease (false negative) was incorrectly diagnosed by combined assessment in 4 of the 529 malignant masses (sensitivity 0.99; predictive value 0.98): cytological diagnoses were of fat necrosis (2) and benign cells on cytospin (1) and aspiration biopsy (1); mammographic diagnoses were of benign disease (2) and normality (2). Indeterminate ('atypical', 'suspicious') diagnoses were problematic and frequent (overall 223 (31.6%), malignant masses 137 (25.9%), benign masses 86 (48.9%); cytology 117 (16.6%), mammography 141 (20%). Thus, with the combined assessment of mammography and cytology in clinically suspicious breast masses, a decisive diagnosis was made in about two-thirds of cases allowing the safe commencement of therapy; the balance of patients required core or excision biopsy.
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Affiliation(s)
- W F van Wyk
- Department of Surgery, Groote Schuur Hospital
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25
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Bailie R, Barron P, Learmonth G. Towards a rational cervical cytology screening strategy. Case study of a peri-urban settlement. S Afr Med J 1995; 85:30-3. [PMID: 7784914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVES To assess cervical cytology screening activity in a peri-urban settlement near Cape Town, with a view to informing rational policy development. METHOD Total and age-specific prevalence rates of women who had been screened, relative prevalence by age group of women who had not been screened, and yield of screening were estimated from cytopathology laboratory records and available demographic data. Age-specific prevalence rates among women who had been screened were compared with age at presentation with cervical cancer at the referral hospital. Attendance for colposcopy follow-up was assessed from colposcopy clinic records. RESULTS The number of smears taken and the prevalence of women who had been screened peaked in the 20 - 24-year age group, and declined to low levels in those over the age of 40 years. The relative prevalence of those who had not had a smear exceeded 9 in all age groups over 39 years, compared with women of 20 - 24 years. Smears which showed signs of CIN III, malignancy or possible malignancy comprised 0.13%. Thirty-six per cent of women booked for colposcopy did not attend. CONCLUSIONS Efficiency of screening could be improved by emphasising coverage of higher-risk age groups, e.g. women over the age of 30 years, and better follow-up.
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Affiliation(s)
- R Bailie
- Department of Community Health, University of Cape Town
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Learmonth G, Marks RK, Hunt J, Narramore C. The cytological recognition of African siderosis on bone smears. Cytopathology 1991; 2:205-13. [PMID: 1954322 DOI: 10.1111/j.1365-2303.1991.tb00406.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Eight cases of African siderosis primarily recognized on cytological smears are presented and discussed. All the smears were obtained from Jamshidi needle biopsies of vertebral bodies. Six cases showed siderosis only, while a seventh showed two pathological processes on one slide, namely metastatic keratinizing squamous carcinoma and siderosis. The remaining case showed cytological evidence of tuberculosis and siderosis. All cases were histologically confirmed, an additional feature in two cases being osseous tuberculosis which was not evident on the cytological smears. A search of the literature failed to reveal any report on the cytological recognition of this disease, or its association with tuberculosis.
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Affiliation(s)
- G Learmonth
- Cytopathology Laboratory, Groote Schuur Hospital, University of Cape Town, South Africa
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27
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Soeters R, Tiltman A, Learmonth G, Bloch B, Dehaeck K, Levin W. Peutz-Jeghers syndrome in association with adenoma malignum (minimal deviation adenocarcinoma) of the cervix. Case report. Br J Obstet Gynaecol 1989; 96:1101-4. [PMID: 2804013 DOI: 10.1111/j.1471-0528.1989.tb03390.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R Soeters
- Gynaecological Oncology Unit, Groote Schuur Hospital and University of Cape Town, Republic of South Africa
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28
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Goldberg G, Learmonth G, Bloch B, Levin W. Role of cul-de-sac aspiration cytology in the management and follow-up of patients with ovarian carcinoma. A preliminary report. J Reprod Med 1985; 30:867-70. [PMID: 4078821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In a pilot study involving 44 patients on combined chemotherapy for epithelial ovarian carcinoma, cul-de-sac aspiration cytology was compared with second-look surgery in the evaluation of disease status. There was a 92% correlation. Our preliminary conclusion was that an aspirate from the cul-de-sac or peritoneal cavity can be obtained with ease and that if this finding is confirmed in a larger series now in progress, the procedure may in part replace second-look operations in the management of these patients.
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29
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Learmonth G. Sporotrichosis in Canada. Can Med Assoc J 1955; 72:864. [PMID: 20325064 PMCID: PMC1825890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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