Maruta Jun, Spielman Lisa A, Rajashekar Umesh, Ghajar Jamshid
Brain Trauma Foundation, New York, NY, United States.
Department of Neurosurgery, Stanford University, Stanford, CA, United States.
Front Neurol. 2017 Nov 30;8:640. doi: 10.3389/fneur.2017.00640. eCollection 2017.
A moving target is visually tracked with a combination of smooth pursuit and saccades. Human visual tracking eye movement develops through early childhood and adolescence, and declines in senescence. However, the knowledge regarding performance changes over the life course is based on data from distinct age groups in isolation using different procedures, and thus is fragmented. We sought to describe the age-dependence of visual tracking performance across a wide age range and compare it to that of simple visuo-manual reaction time. We studied a cross-sectional sample of 143 subjects aged 7-82 years old (37% male). Eye movements were recorded using video-oculography, while subjects viewed a computer screen and tracked a small target moving along a circular trajectory at a constant speed. For simple reaction time (SRT) measures, series of key presses that subjects made in reaction to cue presentation on a computer monitor were recorded using a standard software. The positional precision and smooth pursuit velocity gain of visual tracking followed a U-shaped trend over age, with best performances achieved between the ages of 20 and 50 years old. A U-shaped trend was also found for mean reaction time in agreement with the existing literature. Inter-individual variability was evident at any age in both visual tracking and reaction time metrics. Despite the similarity in the overall developmental and aging trend, correlations were not found between visual tracking and reaction time performances after subtracting the effects of age. Furthermore, while a statistically significant difference between the sexes was found for mean SRT in the sample, a similar difference was not found for any of the visual tracking metrics. Therefore, the cognitive constructs and their neural substrates supporting visual tracking and reaction time performances appear largely independent. In summary, age is an important covariate for visual tracking performance, especially for a pediatric population. Since visual tracking performance metrics may provide signatures of abnormal neurological or cognitive states independent of reaction time-based metrics, further understanding of age-dependent variations in normal visual tracking behavior is necessary.
移动目标通过平滑追踪和扫视的组合进行视觉跟踪。人类视觉跟踪眼动在幼儿期和青春期发育，并在衰老过程中下降。然而，关于生命过程中表现变化的知识是基于来自不同年龄组的数据，这些数据是通过不同程序单独收集的，因此是零散的。我们试图描述广泛年龄范围内视觉跟踪性能的年龄依赖性，并将其与简单视觉手动反应时间进行比较。我们研究了143名年龄在7至82岁之间的受试者（37%为男性）的横断面样本。使用视频眼动描记法记录眼动，受试者观看电脑屏幕并跟踪一个以恒定速度沿圆形轨迹移动的小目标。对于简单反应时间（SRT）测量，使用标准软件记录受试者对电脑显示器上提示呈现做出反应时进行的一系列按键操作。视觉跟踪的位置精度和平滑追踪速度增益随年龄呈U形趋势，在20至50岁之间表现最佳。平均反应时间也发现了U形趋势，与现有文献一致。在视觉跟踪和反应时间指标的任何年龄，个体间差异都很明显。尽管总体发育和衰老趋势相似，但在减去年龄影响后，视觉跟踪和反应时间表现之间未发现相关性。此外，虽然在样本中发现男女平均SRT存在统计学显著差异，但在任何视觉跟踪指标中均未发现类似差异。因此，支持视觉跟踪和反应时间表现的认知结构及其神经底物在很大程度上似乎是独立的。总之，年龄是视觉跟踪性能的一个重要协变量，尤其是对于儿科人群。由于视觉跟踪性能指标可能提供独立于基于反应时间的指标的异常神经或认知状态的特征，因此有必要进一步了解正常视觉跟踪行为中与年龄相关的变化。
