The individual alpha peak frequency (IAPF) of the human electroencephalography (EEG) typically experiences slowing with increasing age. Despite this hallmark change, studies that investigate modulations of conventional EEG alpha power and connectivity by aging and age-related neuropathology neglect to account for intergroup differences in IAPF. To investigate the relationship of age-related IAPF slowing with EEG power and connectivity, we recorded eyes-closed resting-state EEG in 37 young adults and 32 older adults. We replicated the finding of a slowed IAPF in older adults. IAPF values were significantly correlated with the frequency of maximum global connectivity and the means of their distributions did not differ, suggesting that connectivity was highest at the IAPF. Older adults expressed reduced global EEG power and connectivity at the conventional upper alpha band (10-12 Hz) compared with young adults. By contrast, groups had equivalent power and connectivity at the IAPF. The results suggest that conventional spectral boundaries may be biased against older adults or any group with a slowed IAPF. We conclude that investigations of alpha activity in aging and age-related neuropathology should be adapted to the IAPF of the individual and that previous findings should be interpreted with caution. EEG in the dominant alpha range may be unsuitable for examining cortico-cortical connectivity due to its subcortical origins.

Recent electrophysiological and behavioral studies have found similarities in the neurology of pursuit and saccadic eye movements. In a previous study on eye movements using closely matched paradigms for pursuit and saccades, we revealed that both exhibit bimodal distributions of latency to predictable (PRD) and randomized (RND) stimuli; however, the latency to each type of stimulus was different, and there was more segregation of latencies in saccades than pursuit (Burke MR, Barnes GR. 2006. Quantitative differences in smooth pursuit and saccadic eye movements in humans. Exp Brain Res. 175(4):596-608). To investigate the brain areas involved in these tasks, and to search for correlates of behavior, we used functional magnetic resonance imaging during equivalent PRD and RND target presentations. In the contrast pursuit > saccades, which reflects velocity-dependent versus position-dependent activities, respectively, we found higher activation in the dorsolateral prefrontal cortex (DLPFC) for pursuit and in the frontopolar region for saccades. In the contrast RND > PRD, which principally reflects activation related to visually driven versus memory-driven responses, respectively, we found a higher sustained level of activation in the frontal eye fields during visually guided eye movements. The reverse contrast revealed higher activity for the memory-guided responses in the supplementary eye fields and the superior parietal lobe. In addition, we found learning-related activation during the PRD condition in visual area V5, the DLPFC, and the cerebellum.

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Several brief cognitive tests have shown promising diagnostic test accuracy results for identifying aMCI. However, concerns over the quality of the constituent studies and lack of evidence on the predictive validity of these tests mean that new validation studies are warranted. Copyright © 2016 John Wiley & Sons, Ltd.

Recently it has been suggested that smooth pursuit (SP) and saccadic (SAC) eye movements share many common brain substrates in the planning and control of eye movements (Krauzlis in J Neurophysiol 91:591-603, 2004). Evidence is mounting that these two types of eye movements may also share similar mechanisms used to drive both reactive and predictive eye movement responses (Missal and Keller in J Neurophysiol 88:1880-1892, 2002, Keller and Missal in Ann NY Acad Sci 1004:29-39, 2003). The objective of this study was to quantify these similarities by establishing whether the behavioural response properties of human eye movements to predictive (PRD) and randomized (RND) conditions are quantitatively similar for both SP and SAC in directly comparable paradigms. Two previous studies have attempted to evaluate the coordination and motor preparation time of SP and saccadic eye movements (Erkelens in Vis Res 46:163-170, 2006; Joiner and Shelhamer in Exp Brain Res, Epub ahead of print, 2006). However, no previous study has quantitatively evaluated PRD and RND conditions to discretely presented SP and SAC tasks. We used simple SAC and SP paradigms in blocks of PRD and RND presentations, with eye movements monitored throughout using an IR-limbus eye-tracking system (Skalar). Twelve normal subjects (aged between 20 and 39 years) participated in the study which took place over two recording sessions, on two separate days. Data were analysed for two main comparable descriptive statistics: latency and eye velocity/displacement gain. The results presented here support the notion that SP and SAC share common brain substrates/mechanisms in the generation of responses to PRD and RND visual targets but differ in the movement preparation time.

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Learning to write requires the repeated manual production of spatial patterns. It remains unclear whether tracing or copying provides better training: tracing provides accurate and immediate performance feedback, whereas copying may require greater use of memory and recall during training. We asked sixteen adults to copy or trace novel patterns then reproduce these from memory using a stylus and tablet PC. A week later, a retention test was performed. Sophisticated analyses indexed the extent to which participants had learned the dimensions and shape of patterns. We found that participants: (a) showed better shape and dimensional accuracy when tracing; (b) had better shape and dimensional retention immediately after tracing; (c) showed no differences between copying and tracing in their ability to redraw the pattern (shape or dimensions) 1 week later. Our methods provide a useful starting point for examining training and feedback on the generation and recall of spatial patterns.

Published paperKeyword: cognition, eye movements, tracking, motor control AbstractWe used passive and active following of a predictable smooth pursuit stimulus in order to establish if predictive eye movement responses are equivalent under both passive and active conditions. The smooth pursuit stimulus was presented in pairs that were either 'predictable' in which both presentations were matched in timing and velocity, or 'randomized' in which each presentation in the pair was varied in both timing and velocity. A visual cue signaled the type of response required from the subject; a green cue indicated the subject should follow both the target presentations (Go-Go), a pink cue indicated that the subject should passively observe the 1 st target and follow the 2 nd target (NoGo-Go), and finally a green cue with a black cross revealed a randomized (Rnd) trial in which the subject should follow both presentations. The results revealed better prediction in the Go-Go trials than in the NoGo-Go trials, as indicated by higher anticipatory velocity and earlier eye movement onset (latency). We conclude that velocity and timing information stored from passive observation of a moving target is diminished when compared to active following of the target. This study has significant consequences for understanding how visuomotor memory is generated, stored and subsequently released from shortterm memory. 1) IntroductionHumans are able to produce predictive smooth eye movements to a moving visual stimulus that has been presented previously (Barnes and Donelan, 1999). However, they are unable to initiate and maintain smooth pursuit in the absence of either the target or expectation about the target reappearance (Kowler and Steinman, 1979;Kowler et al., 1984;Kao and Morrow, 1994). More recently it has been discovered that humans are even able to produce anticipatory eye movements to a smooth pursuit stimulus after initially viewing, but not actually following, the target, even though the target moves progressively into the peripheral field during the initial presentation (Barnes et al, 1997). Barnes et al (1997) showed that stimulus information can be stored when the same smooth pursuit stimulus is repeated several times during passive viewing. A subsequent experiment revealed that subjects can even extract visual motion information from two stimuli when they are presented simultaneously but move with different velocity in the same direction in the horizontal plane (Poliakoff et al, 2005). The authors found that there was a slight detriment in scaling eye velocity 100ms after target onset (V100) to the target velocity if the subjects were not cued about which target to follow. Cognitive cues have been used previously to elicit predictive smooth pursuit eye movements (Kowler, 1989;Jarrett and Barnes, 2002). These previous studies used a symbolic or verbal cue to indicate the direction and/or velocity of motion in the upcoming target. The experiment presented here does not provide any information about the direction/velocity of the t...