Altered connectivity among emotion-related brain regions during short-term memory in Alzheimer’s disease. Neurobiol

Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada.
Neurobiology of aging (Impact Factor: 5.01). 05/2010; 31(5):780-6. DOI: 10.1016/j.neurobiolaging.2008.06.002
Source: PubMed


A PET study of patients with Alzheimer's disease (AD) engaged in a delayed match-to-sample face recognition task revealed that performance declines as a function of increasing delay, a pattern accompanied by reduced functional connectivity of prefrontal cortex but increased connectivity of the left amygdala. Here, we characterize the changes in interactions within this amygdalar circuit across the memory delays using structural equation modeling. The magnitude of effective connections was found to be much greater in the patients than in the controls, notably from the left amygdala to left inferior prefrontal cortex, which, in turn, influenced its right homologue. The influence from the amygdala to the left hippocampus, in contrast, was not strong in either group. We interpret this pattern of interactions as possibly reflecting the compensatory recruitment of a dynamic neural network, perhaps involved in implicit emotional processing, in the context of a faulty executive maintenance and retrieval system.

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Available from: R. Shayna Rosenbaum
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    • "In detail, with regards to WM functions, Perrin et al. [35] found that AD patients' picture recall did not benefit from positive emotional context (a positive sound associated to the picture) and again explained this data in terms of WM limitations due to amygdala atrophy and early frontotemporal dysfunctions. More interesting is the PET study by Rosenbaum et al. [36] which found preserved influence from the left amygdala and left hippocampus on left and then right inferior PFC, in the absence of a direct amygdala-hippocampus influence using a match-to-sample face recognition task. This data seems to indicate that DAT patients may still use some emotional brain circuits and show an emotional enhancement effect in WM despite their well-known amygdala and hippocampus deficits. "
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    ABSTRACT: A number of recent studies have reported that working memory does not seem to show typical age-related deficits in healthy older adults when emotional information is involved. Differently, studies about the short-term ability to encode and actively manipulate emotional information in dementia of Alzheimer's type are few and have yielded mixed results. Here, we review behavioural and neuroimaging evidence that points to a complex interaction between emotion modulation and working memory in Alzheimer's. In fact, depending on the function involved, patients may or may not show an emotional benefit in their working memory performance. In addition, this benefit is not always clearly biased (e.g., towards negative or positive information). We interpret this complex pattern of results as a consequence of the interaction between multiple factors including the severity of Alzheimer's disease, the nature of affective stimuli, and type of working memory task.
    Full-text · Article · Feb 2014 · International Journal of Alzheimer's Disease
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    • "Alzheimer's disease Georgopoulos et al. (2007), Güntekin et al. (2008), Locatelli et al. (1998), Rosenbaum et al. (2008), Stam et al. (2006, 2007a, b 2009), Zhou et al. (2008) Epileptic seizures Ponten et al. (2007) Intra-arterial amobarbital injection Douw et al. (2010) Autism spectrum disorder Belmonte et al. (2004), Just et al. (2004), Kana et al. (2007), Murias et al. (2007), Rippon et al. (2006), Vidal et al. (2006) Brain tumors Bartolomei et al. (2006), Bosma et al. (2008) Multiple sclerosis Georgopoulos et al. (2007), Lenne et al. (2012) Preterm birth Mullen et al. (2011) PTSD Lanius et al. (2004), Shaw 2002 Schizophrenia Breakspear et al. (2003), Georgopoulos et al. (2007), Lawrie et al. (2002), Lynall et al. (2010), Michelyannis et al. (2006), Symond et al. (2005) Stroke Grefkes and Fink (2012) Traumatic brain injury Cao and Slobounov 2010), Castellanos et al. (2010, 2011a, b), Ham and Sharp 2012), Kasahara et al. (2010), Kumar et al. (2009), Nakamura et al. (2009), Sponheim et al. (2011), Tsirka et al. (2011) "
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    ABSTRACT: Correlations between ten-channel EEGs obtained from thirteen healthy adult participants were investigated. Signals were obtained in two behavioral states: eyes open no task and eyes closed no task. Four time domain measures were compared: Pearson product moment correlation, Spearman rank order correlation, Kendall rank order correlation and mutual information. The psychophysiological utility of each measure was assessed by determining its ability to discriminate between conditions. The sensitivity to epoch length was assessed by repeating calculations with 1, 2, 3, …, 8 s epochs. The robustness to noise was assessed by performing calculations with noise corrupted versions of the original signals (SNRs of 0, 5 and 10 dB). Three results were obtained in these calculations. First, mutual information effectively discriminated between states with less data. Pearson, Spearman and Kendall failed to discriminate between states with a 1 s epoch, while a statistically significant separation was obtained with mutual information. Second, at all epoch durations tested, the measure of between-state discrimination was greater for mutual information. Third, discrimination based on mutual information was more robust to noise. The limitations of this study are discussed. Further comparisons should be made with frequency domain measures, with measures constructed with embedded data and with the maximal information coefficient.
    Full-text · Article · Feb 2014 · Cognitive Neurodynamics
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    • "Emotion is thought to support the formation of stable and durable representations of past experiences in long term memory [22]. Dere et al. [22] suggested that a deafferentiation of the hippocampus from emotional input, which might be required for episodic memory formation, could explain the development of memory and learning impairments throughout the course of AD [15]. The episodic memory impairment observed in MCI and early AD using explicit memory tasks frequently overlaps [23,24] albeit not all MCI patients will progress to AD. "
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    ABSTRACT: Relative to intentional memory encoding, which quickly declines in Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD), incidental memory for emotional stimuli appears to deteriorate more slowly. We hypothesised that tests of incidental emotional memory may inform on different aspects of cognitive decline in MCI and AD. Patients with MCI, AD and Healthy Controls (HC) were asked to attend to emotional pictures (i.e., positive and neutral) sequentially presented during an fMRI session. Attention was monitored behaviourally. A surprise post-scan recognition test was then administered. The groups remained attentive within the scanner. The post-scan recognition pattern was in the form of (HC = MCI) > AD, with only the former group showing a clear benefit from emotional pictures. fMRI analysis of incidental encoding demonstrated clusters of activation in para-hippocampal regions and in the hippocampus in HC and MCI patients but not in AD patients. The pattern of activation observed in MCI patients tended to be greater than that found in HC. The results suggest that incidental emotional memory might offer a suitable platform to investigate, using behavioural and fMRI measures, subtle changes in the process of developing AD. These changes seem to differ from those found using standard episodic memory tests. The underpinnings of such differences and the potential clinical use of this methodology are discussed in depth.
    Full-text · Article · Mar 2013 · BMC Psychiatry
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