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Mind & Brain, the Journal of Psychiatry Word list memory Word list recall Word list recognition Word list rejection Verbal fluency Naming


lobes are associated with episodic memory impairment in AD. Left frontal cortex activation may also indicate the involvement of the central executive in the task.32 Alterna- tively, Desgranges et al.27 relate their finding of a significant correlation between verbal episodic memory scores and right posterior association cortex activation to an extended HERA model that refers to predominantly right-sided temporal and parietal activation during episodic memory performance.33 They hypothesized that AD patients might rely on right posterior association cortices since these were less severely affected than left-sided areas. In this context, a disease- specific compensatory mechanism of neural function has to be discussed.34 Moreover, word list recognition performance was significantly correlated with anterior cingulate activation, a finding that was frequently observed in studies using episodic memory tasks.35,36 The anterior cingulum has also been found to be correlated with story-recall scores in AD.27,37 Correct rejection of words scores were significantly correlated with frontal but also with left parahippocampal and uncus glucose metabolism. This finding is in accordance with studies hypothesizing an important role of left-side limbic structures in conscious recollection of information.27 In addition, our results indicate an involvement of the left middle temporal gyrus in the task.


Apart from these expected correlations, significant correla- Constructional praxis Constructional praxis recall


Figure 2. Significant correlations between CERAD neuropsychological test performance and regional cerebral glucose metabolism as obtained from SPM analysis (n75).


praxis recall test scores significantly correlated with right medial and superior frontal cortices (Figure 2; Table 2).


DISCUSSION The present study yielded two major findings: (1) a


demonstration that CERAD subscores differentially refer to changes in distinct cerebral sites and (2) evidence that these patterns apply in patients with AD and MCI as the putative preclinical state.


Concerning immediate word list performance, the signifi-


cant correlations with regional cerebral glucose metabolism are in accordance with earlier studies that investigated episodic memory function in patients with AD.27 Activation of the right frontal cortex has been reported both in healthy persons28 and in AD,29 and fits the HERA model.11 The significant correlation of left-sided frontal activation and word list recall scores concurs with the findings of McGeer et al.30 and Waldemar et al.31 who suggested that both frontal


M&B 2011; 2:(1). July 2011 4


tions between word recognition scores and left insula cortex arose. Insula cortex activation has been described in neuroi- maging studies of pain and distress,38 but recently it was associated with negative emotions during decision making.39 Interestingly, the insular cortex of the language-dominant hemisphere has been described to be associated with temporal sequencing of the articulatory programming.40 We also found a significant correlation between word recognition scores and the nucleus lentiformis, which had already been described to correlate significantly with scores of successful classification learning.41 The finding of a significant correla- tion with the right caudate concurs with a study by Thomas et al.42 who found a significant correlation between implicit learning performance and right caudate activation using functional MRI.


As hypothesized, significant correlations between verbal


fluency and left temporo-parietal and frontal cortices oc- curred. This finding could be predicted on the basis of activation studies43 but also agrees with recent studies in AD patients.27 Furthermore, verbal semantic memory impairment was related to focal lesions of the respective structures.44 In accordance with Bracco et al.15 we found a significant correlation with the right middle frontal cortex, indicating that verbal fluency may also rely on larger neural networks. As to be expected, naming scores were significantly correlated with left temporo-parietal and parahippocampal cortices27 while a significant correlation with the right temporal cortices referred to potential compensatory mechanisms.


The significant correlation found between constructional praxis scores and temporo-frontal cortices activation refers to a neural network specifically involved in praxis performance. Since mildly impaired patients were also included in the


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