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Stuart S, Lawson RA, Yarnall AJ, Nell J, Alcock L, Duncan GW, Khoo TK, Barker RA, Rochester L, Burn DJ. Pro-Saccades Predict Cognitive Decline in Parkinson's Disease: ICICLE-PD. Mov Disord 2019; 34:1690-1698. [PMID: 31442355 DOI: 10.1002/mds.27813] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 07/10/2019] [Accepted: 07/12/2019] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Cumulative dementia incidence in Parkinson's disease (PD) is significant, with major personal and socioeconomic impacts on individuals with PD and their carers. Early identification of dementia risk is vital to ensuring optimal intervention. Saccadic deficits often distinguish neurodegenerative disorders and cognitive impairment, but their ability to predict cognitive decline in PD has yet to be determined. The aims of this study were to (1) evaluate baseline (6.4 ± 6.1 months since PD diagnosis) differences in pro-saccadic metrics between those with early PD and healthy age-matched adults; and (2) assess the ability of baseline pro-saccades to predict subsequent cognitive decline over 4.5 years. METHODS One hundred and forty-one PD and 90 age-matched participants recruited at diagnosis underwent saccadometric assessment of pro-saccades at baseline and had cognition assessed at baseline, 18, 36, and 54 months. Pro-saccadic characteristics included latency, duration, amplitude, peak, and average velocity. Cognitive assessment included executive function, attention, fluctuating attention, and memory. Linear mixed-effects models examined pro-saccadic metrics as predictors of cognitive decline over 54 months. RESULTS Pro-saccades were significantly impaired at baseline in PD compared with controls. Pro-saccadic characteristics of latency, duration, peak, and average velocity predicted decline in global cognition, executive function, attention, and memory over 54 months in PD. In addition, only reduction in global cognition and attention were predicted by pro-saccadic metrics in age-matched adults, indicating that PD findings were not purely age related. CONCLUSIONS Saccadic characteristics are impaired in early PD and are predictive of cognitive decline in several domains. Assessment of saccades may provide a useful non-invasive biomarker for long-term PD cognitive decline in early disease. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Samuel Stuart
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK.,Department of Neurology, Balance Disorders Laboratory, Oregon Health & Science University, Portland, Oregon, USA
| | - Rachael A Lawson
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK
| | - Alison J Yarnall
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK
| | - Jeremy Nell
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK.,Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - Lisa Alcock
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK
| | - Gordon W Duncan
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Tien K Khoo
- School of Medicine & Menzies Health Institute Queensland, Griffith University, Australia.,School of Medicine, University of Wollongong, Wallongong, New South Wales, Australia
| | - Roger A Barker
- Cambridge University, John van Geest Centre for Brain Repair and Department of Neurology, E.D. Adrian Building, Cambridge, UK
| | - Lynn Rochester
- Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne, UK.,Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK
| | - David J Burn
- Faculty of Medical Science, Newcastle University, Newcastle Upon Tyne, UK
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Dalmaso M, Castelli L, Galfano G. Microsaccadic rate and pupil size dynamics in pro-/anti-saccade preparation: the impact of intermixed vs. blocked trial administration. PSYCHOLOGICAL RESEARCH 2019; 84:1320-1332. [PMID: 30603866 DOI: 10.1007/s00426-018-01141-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/21/2018] [Indexed: 01/02/2023]
Abstract
Prolonged fixation can lead to the generation of tiny and fast eye movements called microsaccades, whose dynamics can be associated with higher cognitive mechanisms. Saccade preparation is also reflected in microsaccadic activity, but the few studies on this topic provided mixed results. For instance, fewer microsaccades have been observed when participants were asked to prepare for an anti-saccade (i.e., a saccade in the opposite direction to the target) as compared to a pro-saccade (i.e., a saccade executed towards a target), but null results have also been reported. In the attempt to shed new light on this topic, two experiments were carried out in which the context of presentation of pro- and anti-saccade trials was manipulated. Pupil size was also recorded, as a further index of cognitive load. In Experiment 1, participants were asked to prepare and perform pro- and anti-saccades in response to a peripheral target, according to a central instruction cue provided at the beginning of each trial (intermixed condition). In Experiment 2, the same task was employed, but pro- and anti-saccade trials were delivered in two distinct blocks (blocked condition). In both experiments, greater saccadic latencies and lower accuracy emerged for anti- than for pro-saccades. However, in the intermixed condition, a lower microsaccadic rate and a greater pupil size emerged when participants prepared for anti- rather than pro-saccades, whereas these differences disappeared in the blocked condition. These results suggest that contextual factors may play a key role in shaping oculomotor dynamics linked to saccade preparation.
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Affiliation(s)
- Mario Dalmaso
- Department of Developmental and Social Psychology, University of Padova, Via Venezia 8, 35131, Padua, Italy.
| | - Luigi Castelli
- Department of Developmental and Social Psychology, University of Padova, Via Venezia 8, 35131, Padua, Italy
| | - Giovanni Galfano
- Department of Developmental and Social Psychology, University of Padova, Via Venezia 8, 35131, Padua, Italy
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Pierce JE, McDowell JE. Modulation of cognitive control levels via manipulation of saccade trial-type probability assessed with event-related BOLD fMRI. J Neurophysiol 2015; 115:763-72. [PMID: 26609113 DOI: 10.1152/jn.00776.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/19/2015] [Indexed: 11/22/2022] Open
Abstract
Cognitive control supports flexible behavior adapted to meet current goals and can be modeled through investigation of saccade tasks with varying cognitive demands. Basic prosaccades (rapid glances toward a newly appearing stimulus) are supported by neural circuitry, including occipital and posterior parietal cortex, frontal and supplementary eye fields, and basal ganglia. These trials can be contrasted with complex antisaccades (glances toward the mirror image location of a stimulus), which are characterized by greater functional magnetic resonance imaging (MRI) blood oxygenation level-dependent (BOLD) signal in the aforementioned regions and recruitment of additional regions such as dorsolateral prefrontal cortex. The current study manipulated the cognitive demands of these saccade tasks by presenting three rapid event-related runs of mixed saccades with a varying probability of antisaccade vs. prosaccade trials (25, 50, or 75%). Behavioral results showed an effect of trial-type probability on reaction time, with slower responses in runs with a high antisaccade probability. Imaging results exhibited an effect of probability in bilateral pre- and postcentral gyrus, bilateral superior temporal gyrus, and medial frontal gyrus. Additionally, the interaction between saccade trial type and probability revealed a strong probability effect for prosaccade trials, showing a linear increase in activation parallel to antisaccade probability in bilateral temporal/occipital, posterior parietal, medial frontal, and lateral prefrontal cortex. In contrast, antisaccade trials showed elevated activation across all runs. Overall, this study demonstrated that improbable performance of a typically simple prosaccade task led to augmented BOLD signal to support changing cognitive control demands, resulting in activation levels similar to the more complex antisaccade task.
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Affiliation(s)
- Jordan E Pierce
- Department of Psychology, University of Georgia, Athens, Georgia
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