Wester K, Irvine D R, Hugdahl K
Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
J Neurol. 2001 Aug;248(8):676-83. doi: 10.1007/s004150170113.
Thalamic lesions have been shown to produce severe cognitive deficits involving language and memory. A majority of the studies have reported cognitive deficits after lesions in the anterior and dorsomedial thalamic nuclei. We report five case studies of effects on language processing after postero-dorsal thalamic haemorrhages. Four of the patients had lesions on the right side, and one patient had a lesion on the left side. Effects on language processing were investigated with the dichotic listening test with consonant-vowel syllables. This test, in which conflicting auditory stimuli are presented simultaneously to the two ears, has been used to probe differences in language processing in the left and right hemispheres. The four patients with right-sided lesions reported almost none of the syllables presented to the left ear, and were unable to modify this massive right ear advantage by directing attention to the left or right ear. The patient with a left-sided lesion showed a weaker left ear advantage, and was able to modify his responses by shifting attention, to an extent similar to that of healthy reference individuals. When tested with monaural stimulus presentation, the scores of all patients rose to almost 100% correct for each ear. The pattern of effects with dichotic stimuli under different instructional conditions cannot be accounted for in purely structural terms, and indicates that lesions in the posterior part of the thalamus, including the pulvinar nucleus and medial geniculate body, produce deficits not only in processing of complex auditory stimuli but also in the allocation of attention to input from one ear or the other.
丘脑病变已被证明会导致严重的认知缺陷，涉及语言和记忆。大多数研究报告称，丘脑前核和背内侧核受损后会出现认知缺陷。我们报告了5例丘脑后背部出血对语言加工影响的病例研究。其中4例患者右侧有病变，1例患者左侧有病变。通过使用辅音-元音音节的双耳分听测试来研究对语言加工的影响。该测试同时向两只耳朵呈现相互冲突的听觉刺激，已被用于探究左右半球语言加工的差异。4例右侧病变患者几乎没有报告左耳呈现的音节，并且无法通过将注意力转向左耳或右耳来改变这种明显的右耳优势。左侧病变的患者左耳优势较弱，并且能够通过转移注意力来改变他的反应，其程度与健康对照个体相似。当用单耳刺激呈现进行测试时，所有患者每只耳朵的得分几乎都达到了100%正确。在不同指导条件下双耳刺激的效应模式不能单纯用结构术语来解释，这表明丘脑后部的病变，包括枕核和内侧膝状体，不仅会导致复杂听觉刺激加工的缺陷，还会导致对来自一只耳朵或另一只耳朵输入的注意力分配的缺陷。
