Birkbeck, University of London, UK.
Cogn Neuropsychol. 2005;22(8):959-1004. doi: 10.1080/02643290442000419.
Action selection in everyday goal-directed tasks of moderate complexity is known to be subject to breakdown following extensive frontal brain injury. A model of action selection in such tasks is presented and used to explore three hypotheses concerning the origins of action disorganisation: that it is a consequence of reduced top-down excitation within a hierarchical action schema network coupled with increased bottom-up triggering of schemas from environmental sources, that it is a more general disturbance of schema activation modelled by excessive noise in the schema network, and that it results from a general disturbance of the triggering of schemas by object representations. Results suggest that the action disorganisation syndrome is best accounted for by a general disturbance to schema activation, while altering the balance between top-down and bottom-up activation provides an account of a related disorder-utilisation behaviour. It is further suggested that ideational apraxia (which may result from lesions to left temporoparietal areas and which has similar behavioural consequences to action disorganisation syndrome on tasks of moderate complexity) is a consequence of a generalised disturbance of the triggering of schemas by object representations. Several predictions regarding differences between action disorganisation syndrome and ideational apraxia that follow from this interpretation are detailed.
在日常具有中等复杂度的目标导向任务中，行动选择已知会在广泛的额叶脑损伤后出现故障。本文提出了一种此类任务中的行动选择模型，并用于探索有关行动失调起源的三个假设：它是层次行动图式网络中自上而下的兴奋减少，以及环境来源的图式自下而上触发增加的结果；它是图式网络中过度噪声建模的更一般的图式激活干扰；它是由对象表示触发图式的一般干扰引起的。结果表明，行动失调综合征最好通过图式激活的一般干扰来解释，而改变自上而下和自下而上激活之间的平衡则可以解释相关的障碍-利用行为。进一步表明，意念性失用症（可能由左颞顶区域的病变引起，并且在中等复杂度的任务上与行动失调综合征具有相似的行为后果）是由对象表示触发图式的一般性干扰引起的。根据这一解释，详细说明了关于行动失调综合征和意念性失用症之间差异的几个预测。
