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Static, Low-Frequency, and Pulsed Magnetic Fields in Biological Systems
Published in James C. Lin, Electromagnetic Fields in Biological Systems, 2016
Hamidi, Tononi, and Postle (2008) conducted a functional neuroimaging study for investigating which specific regions of the frontal and the posterior parietal cortices contribute to the retention of information in spatial working memory using rTMS (10 Hz, produced motor-evoked potential [MEP] ≥50 μν). They assessed the necessity for short-term retention of spatial information of brain areas identified by previous functional imaging studies: dorsolateral prefrontal cortex (DLPFC), FEFs, superior parietal lobule (SPL), and intraparietal sulcus (IPS). The administration of rTMS spanned the 3-second delay period of a spatial delayed-recognition task. The postcentral gyrus (PCG) was included to control any regionally nonspecific effects of rTMS. The only regionally specific effect was a significant decrease in reaction time when rTMS was applied to SPL. Additionally, rTMS lowered accuracy to a greater extent when applied to the left hemisphere than to the right and was more disruptive when applied contralaterally versus ipsilaterally to the visual field in which the memory probe was presented. Although it seems paradoxical, the finding of rTMS-induced improvement in task performance has a precedent and is consistent with the idea that regions associated with spatial sensory-motor processing make necessary contributions to the short-term retention of this information.
The cognitive and neural correlates of written language: a selective review of bilingualism
Published in Journal of the Royal Society of New Zealand, 2021
Karen E. Waldie, Gjurgjica Badzakova-Trajkov, Haeme R. P. Park, Yuxuan Zheng, Denise Neumann, Nasrin Zamani Foroushani
We also observed significant activations in the left and right superior parietal lobule and the left inferior parietal lobule of bilinguals. The parietal cortex is usually not involved in linguistic processes; however, its activation might be explained by its general role in a variety of cognitive functions. Due to more effortful word-form processing, activation of additional cortical regions might be required (Culham and Kanwisher 2001; Wartenburger et al. 2003).
Computation and management of weighted activation vectors in support to fMRI analysis of clinical subjects
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2019
Elisabetta Binaghi, Alberto A. Vergani, Andrea Montalbetti, Renzo Minotto, Valentina Pedoia, Sabina Strocchi, Sergio Balbi
WAVs reported in the left part of Figures 16 and 18 are computed from SPM (Figure 17) generated from pre-operative fMRI data and related to object denomination and verbs generation tasks, respectively. There were activations in the primary motor cortex (ROI 47–50), the premotor cortex (ROI 90, 91) and within the primary and secondary somato-sensitive cortex (ROI 51–60). Regarding the verb generation task, there were activations within the limbic system: amygdala (ROI 8, 9, 11, 12), hippocampus (ROI 17, 18), anterior paracingulate cortex (ROI 144, 145, 147), the left temporal pole (ROI 156) and the left thalamus (ROI 158). There is a predominance of the right hemisphere corresponding to the visual regions: eg the primary visual cortex and extrastriate cortexes V3 and V4; instead, the V5 area is more active in the left brain and V2 has no activation differences. Broca’s areas (ROI 13–16) are equally active. Singular activations, specially associated with the verb generation task, are within the superior longitudinal fascicle (ie arcuate fascicle; ROI 110, 111) and superior fronto-occipital fascicle (ROI 112, 113). Salient contributions are in regions corresponding to the anterior intra-parietal sulcus (ROI 1, 6), the superior parietal lobule (ROI 68, 69 and 73–80), the temporo-occipital portion of the inferior temporal gyrus (ROI 138, 139) and the fusiform cortex (ROI 160, 161); these areas, far from the lesion, have no activation differences. Post-neurosurgical monitoring was performed 3 months later; the corresponding WAVs are shown in the right part of Figures 16 and 18. They are generated from SPMs (Figure 19) of fMRI exams where patient performed verbal tasks. Focusing on verb generation, the activation within the motor and somato-sensitive areas remains well evident. In addition, the amygdala and the paracingulate cortex, right and left, are again significantly active. It is worth noting that there are modifications within visual regions: on the left, V1 and V2 areas are less active than the contralateral regions during the object denomination task, V3 and V4 are not active during both tasks and V5 becomes more active into the right part. There is a light left predominance in the deep inferior parietal lobe. Also along the superior parietal lobe, the activations have deeply changed: in postoperative WAVs, many left regions are not active differently from the pre-surgical fMRI scan (ROI 69, 75, 77) or less active with respect to the right ones (ROI 71, 73, 79).