Fielding Joanne, Georgiou-Karistianis Nellie, Millist Lynette, White Owen
Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry and Psychological Medicine, Clayton Campus, Monash University, Vic. 3800, Australia.
Neurosci Res. 2006 Jan;54(1):57-65. doi: 10.1016/j.neures.2005.10.007. Epub 2005 Nov 14.
A predictive central-cueing paradigm was used to compare visuospatial deficits in patients with Parkinson's (PD) and Huntington's diseases (HD), employing directionally valid and invalid visual cues over a range of stimulus onset asynchronies (SOA) to elicit a saccadic response. Compared to age-matched control groups, both PD and HD patients responded erroneously to cue stimuli more frequently, increasing significantly over longer SOAs. Both valid and invalid cues resulted in elevated latencies compared to un-cued visually guided saccades, the associated 'cost' of invalid cueing significantly greater than that for valid cueing, over all SOAs. Unlike control subjects, PD and HD patients demonstrated temporal variation with cue presentation. For PD patients, latencies following directionally invalid cues were significantly longer for intermediate SOAs, suggesting difficulty overcoming a build-up of inhibitory activity over time. No validity effect was found at 1000 ms. For HD patients, latencies for validly cued saccades with 150 ms SOAs were shorter than latencies for no-cue trials, representing a 'benefit' of valid cueing. For 500 ms SOAs latencies were comparably elevated following directionally valid and invalid cues, and for 1000 ms SOAs neither cue condition resulted in increased latencies. These findings reflect the consequence of disruption to the balance of activity over the basal ganglia facilitatory and inhibitory pathways. Imbalance in PD resulted in difficulty sustaining goal-directed behaviour, and in HD, difficulty gating inappropriate behaviour.
采用一种预测性中央线索范式，通过在一系列刺激起始异步时间（SOA）上使用方向有效和无效的视觉线索来引发扫视反应，比较帕金森病（PD）和亨廷顿舞蹈病（HD）患者的视觉空间缺陷。与年龄匹配的对照组相比，PD和HD患者对线索刺激的错误反应更频繁，且在较长的SOA时显著增加。与无线索的视觉引导扫视相比，有效和无效线索均导致潜伏期延长，在所有SOA中，无效线索相关的“代价”显著大于有效线索。与对照组不同，PD和HD患者在线索呈现时表现出时间变化。对于PD患者，在中间SOA时，方向无效线索后的潜伏期显著更长，表明随着时间推移难以克服抑制活动的积累。在1000毫秒时未发现有效性效应。对于HD患者，150毫秒SOA的有效线索提示的扫视潜伏期比无线索试验的潜伏期短，这代表了有效线索提示的“益处”。对于500毫秒SOA，方向有效和无效线索后的潜伏期相对升高，对于1000毫秒SOA，两种线索条件均未导致潜伏期增加。这些发现反映了基底神经节促进和抑制通路活动平衡被破坏的后果。PD中的失衡导致难以维持目标导向行为，而HD中的失衡导致难以控制不适当行为。
