Dowlati Ehsan, Adams Sarah E, Stiles Alexandra B, Moran Rosalyn J
Virginia Tech Carilion School of Medicine Roanoke, VA, USA.
Virginia Tech Carilion Research Institute Roanoke, VA, USA.
Front Hum Neurosci. 2016 Mar 31;10:141. doi: 10.3389/fnhum.2016.00141. eCollection 2016.
Aging is accompanied by stereotyped changes in functional brain activations, for example a cortical shift in activity patterns from posterior to anterior regions is one hallmark revealed by functional magnetic resonance imaging (fMRI) of aging cognition. Whether these neuronal effects of aging could potentially contribute to an amelioration of or resistance to the cognitive symptoms associated with psychopathology remains to be explored. We used a visual illusion paradigm to address whether aging affects the cortical control of perceptual beliefs and biases. Our aim was to understand the effective connectivity associated with volitional control of ambiguous visual stimuli and to test whether greater top-down control of early visual networks emerged with advancing age. Using a bias training paradigm for ambiguous images we found that older participants (n = 16) resisted experimenter-induced visual bias compared to a younger cohort (n = 14) and that this resistance was associated with greater activity in prefrontal and temporal cortices. By applying Dynamic Causal Models for fMRI we uncovered a selective recruitment of top-down connections from the middle temporal to Lingual gyrus (LIN) by the older cohort during the perceptual switch decision following bias training. In contrast, our younger cohort did not exhibit any consistent connectivity effects but instead showed a loss of driving inputs to orbitofrontal sources following training. These findings suggest that perceptual beliefs are more readily controlled by top-down strategies in older adults and introduce age-dependent neural mechanisms that may be important for understanding aberrant belief states associated with psychopathology.
衰老伴随着大脑功能激活的刻板变化，例如，功能磁共振成像（fMRI）对衰老认知的研究揭示，活动模式从大脑后部到前部区域的皮质转移是衰老的一个标志。衰老的这些神经元效应是否可能有助于改善或抵抗与精神病理学相关的认知症状，仍有待探索。我们使用视觉错觉范式来研究衰老是否会影响对感知信念和偏差的皮质控制。我们的目的是了解与模糊视觉刺激的意志控制相关的有效连接，并测试随着年龄增长，早期视觉网络的自上而下控制是否增强。通过对模糊图像使用偏差训练范式，我们发现与年轻组（n = 14）相比，老年参与者（n = 16）能够抵抗实验者诱导的视觉偏差，并且这种抵抗与前额叶和颞叶皮质的更大活动有关。通过应用功能磁共振成像的动态因果模型，我们发现老年组在偏差训练后的感知转换决策过程中，从中颞叶到舌回（LIN）的自上而下连接有选择性地被激活。相比之下，我们的年轻组没有表现出任何一致的连接效应，而是在训练后显示出眶额源驱动输入的丧失。这些发现表明，老年人的感知信念更容易通过自上而下的策略来控制，并引入了与年龄相关的神经机制，这可能对理解与精神病理学相关的异常信念状态很重要。
