Table 4.
Regional graph topological differences and its relationship with the pathogenesis of ET
| Regional graph topological differences | Function | Possible meaning in ET |
|---|---|---|
| Precuneus/posterior cingulate cortex | Disruption of this network may play an important role in developing Alzheimer's disease (Yokoi et al., 2018) | Older‐onset ET is associated not only with higher odds of prevalent Alzheimer's disease (Benito‐León et al., 2006a), but also with an increased risk of Alzheimer's disease (Bermejo‐Pareja et al., 2007) |
| Frontal operculum | This is a key node in a network for exerting control over cognitive processes (Higo, Mars, Boorman, Buch, & Rushworth, 2011) | Cognitive deficits have been described in ET (Benito‐León et al., 2006b). |
| Right hippocampus and the parahippocampal gyri | Involved in episodic memory (Ekstrom & Bookheimer, 2007) | Memory deficits have been described in ET (Benito‐León et al., 2006b) |
| Left inferior frontal gyrus (pars opercularis) | The posterior part of the inferior frontal gyrus, traditionally referred to as Broca's area, is thought to play a critical role in processing both the phonological aspects and meanings of words, and hence is crucial for language production and comprehension (Gabrieli, Poldrack, & Desmond, 1998) | In population‐based studies and clinical series (Benito‐León et al., 2006b; Puertas‐Martin et al., 2016), verbal fluency has been found to be impaired in ET patients |
| Nucleus accumbens bilaterally | The nucleus accumbens is related with the impulsivity associated with drug addictions (Dalley et al., 2007) and with depression (Francis & Lobo, 2017) | Personality characteristics have been observed in ET; patients are more prone to a personality characterized by greater higher harm avoidance (Thenganatt & Louis, 2012). ET patients also have an increased odds and risk of depression (Louis et al., 2007) |
| Left amygdala | This is a key brain structure regulating different aspects of emotional processing, including recognition of emotional expression in faces, as well as in mediating emotional interference during tasks requiring cognitive resources (Adolphs & Spezio, 2006) | An inverse relation has been described between facial emotion recognition and tremor severity in ET patients (Auzou, Foubert‐Samier, Dupouy, & Meissner, 2014). In addition, ET patients did not perform as well in joy and fear recognition, and they had subtle abnormalities in risk detection (Auzou et al., 2014) |
| Left amygdala and several cerebellar regions | Startle hyporeactivity might be mediated by aberrant cerebellar input to the amygdala, which is involved in priming the startle response in emotional contexts (Lafo et al., 2017) | ET patients respond abnormally in terms of startle reactivity to emotional pictures (Lafo et al., 2017) |
| Parahippocampal gyrus, posterior cingulate, and lingual gyrus bilaterally | These brain regions are involved in visual tasks (Yang, Deng, Xing, Xia, & Li, 2015) | Impaired visual‐motor integration in ET has been described (Bares, Lungu, Husarova, & Gescheidt, 2010). Changes in the connectivity of the lingual gyrus, which may be related to internally directed attention (Benedek et al., 2016), correlated negatively with attention domain |
| Right inferior lateral occipital cortex | The extrastriate body, which is well known to respond to visual processing of static and moving human bodies (Astafiev, Stanley, Shulman, & Corbetta, 2004; Lingnau & Downing, 2015), is located in the lateral occipital cortex. Further, the extrastriate body responds during the perception of other people's body parts or during goal‐directed movements of the observer's body parts (Astafiev et al., 2004; Lingnau & Downing, 2015). Finally, the lateral occipitotemporal cortex represents varied aspects of action, ranging from perception of tools and bodies and the way they typically move (Lingnau & Downing, 2015) | Given the involvement of the lateral occipital cortex in the control of movement, its deterioration could plausibly be involved in the genesis of tremor (Serrano et al., 2017) |
Abbreviation: ET, essential tremor.