Hypnosis, hypnotic suggestibility, and meditation : an integrative review of the associated brain regions and networks

The number of neuroimaging studies on hypnosis and meditation has multiplied rapidly in recent years. The methods and analytic techniques that are being applied are becoming increasingly sophisticated and approaches focusing on connectomics have offered novel ways to investigate the practices, enabling brain function to be investigated like never before. This chapter provides a review of the literature on the effects of hypnosis and meditation on brain network functional connectivity. Numerous cross-sectional as well as longitudinal studies have also reported enduring transformations in brain structure and function in practitioners of meditation, while evidence is mounting which demonstrates a relationship between hypnotic suggestibility and variations in neuroanatomy/functional connectivity that may facilitate hypnosis. The similarities (and differences) between the brain regions and networks associated with each type of practice are highlighted, while links are tentatively made between these and the reported phenomenology

Prolonged cholinergic enrichment influences regional cortical activation in early Alzheimer's disease

Neuroimaging studies of cholinesterase inhibitor (ChEI) treatment in Alzheimer's disease (AD) indicate that the short and long term actions of ChEIs are dissimilar. fMRI studies of the ChEI rivastigmine have focused on its short term action. In this exploratory study the effect of prolonged (20 weeks) rivastigmine treatment on regional brain activity was measured with fMRI in patients with mild AD. Eleven patients with probable AD and nine age-matched controls were assessed with a Pyramids and Palm Trees semantic association and an n-back working memory fMRI paradigm. In the patient group only, the assessment was repeated after 20 weeks of treatment. There was an increase in task-related brain activity after treatment with activations more like those of normal healthy elderly. Behaviorally, however, there were no significant differences between baseline and retest scores, with a range of performance probably reflecting variation in drug efficacy across patients. Variable patient response and drug dynamic/kinetic factors in small patient groups will inevitably bias (either way) the effect size of any relevant drug related changes in activation. Future studies should take drug response into account to provide more insight into the benefits of ChEI drugs at the individual level

Witchcraft, Wealth and Disability: Reinterpretation of a folk belief in contemporary urban Africa

Many groups in sub-Saharan Africa have historically linked persons with disabilities with witchcraft as a component of a wider link between accusations of witchcraft and socially marginalized populations. It is commonly assumed that traditional prejudices towards persons with disabilities are receding in light of urbanization, education, mass media and efforts to confront such prejudice and stigma by governments, disability advocates and civil society. Ratification of the UN Convention on the Rights of Persons with Disabilities (CRPD) by many African countries is considered an additional impetus for change. While beliefs differ throughout the region, there is an unsettling trend in many urban areas where traditional beliefs linking disability with witchcraft are being reinterpreted. Fuelled by quest for rapid social and economic advancement, urban ‘witch doctors’ promote beliefs that individuals and families can prosper if they perform rituals or sacrifice involving abuse, mutilation or killing of children and adults with disabilities. These beliefs are reinforced in popular media and some Pentecostal churches where disability is linked to evil spirits or the devil, while ‘cure’ of disability is linked to virtue and prosperity. Based on literature review and fieldwork in Tanzania and Uganda we argue here that with rapid urbanization, links between witchcraft and disability in contemporary African popular urban culture is an issue of concern that must be acknowledged and addressed

Revealing the differences between normal and pathological ageing using functional magnetic resonance imaging (fMRI)

The aim of the present study was to use fMRI to examine the brain activation patterns found in normal and pathological ageing on specific cognitive tasks. The cognitive paradigms that were chosen, consisted of an n-back working memory task and a semantic memory and processing task. Manipulation of the n-back task enabled vigilance and working memory load to be investigated. Patients with Alzheimer's Disease (AD) and individuals with amnestic Mild Cognitive Impairment (MCI) were compared to normal elderly and young controls. The experiments showed that the patterns of brain activation found in normal and pathological ageing do not appear to fall along the same continuum. When comparing the elderly group to the young group, areas of under-activation could be seen, in addition to other regions of activation which were thought to be due to compensation. The comparison of the normal to the pathological groups revealed distinct differences in the levels and locations of the significant activations. On the vigilance and working memory tasks, the behavioural scores and reaction times of the pathological groups were not significantly different from the normal elderly, yet substantial differences could be identified in the brain activation patterns. The semantic memory task, contrary to expectation, revealed a significant difference in behavioural performance between the young group and the elderly group. Both the reaction times and the performance scores of the AD group were significantly different compared to the elderly, however. Significant differences also occurred in the brain activation patterns of both pathological groups (AD and MCI) compared to the elderly. The differences that were present between the normal and pathological groups on each of the tasks, suggest that sensitive cognitive fMRI paradigms might be very useful in resolving diagnostic ambiguity in people at increased risk of developing AD

Eigenvector alignment : assessing functional network changes in amnestic mild cognitive impairment and Alzheimer's disease

Eigenvector alignment, introduced herein to investigate human brain functional networks, is adapted from methods developed to detect influential nodes and communities in networked systems. It is used to identify differences in the brain networks of subjects with Alzheimer’s disease (AD), amnestic Mild Cognitive Impairment (aMCI) and healthy controls (HC). Well-established methods exist for analysing connectivity networks composed of brain regions, including the widespread use of centrality metrics such as eigenvector centrality. However, these metrics provide only limited information on the relationship between regions, with this understanding often sought by comparing the strength of pairwise functional connectivity. Our holistic approach, eigenvector alignment, considers the impact of all functional connectivity changes before assessing the strength of the functional relationship, i.e. alignment, between any two regions. This is achieved by comparing the placement of regions in a Euclidean space defined by the network's dominant eigenvectors. Eigenvector alignment recognises the strength of bilateral connectivity in cortical areas of healthy control subjects, but also reveals degradation of this commissural system in those with AD. Surprisingly little structural change is detected for key regions in the Default Mode Network, despite significant declines in the functional connectivity of these regions. In contrast, regions in the auditory cortex display significant alignment changes that begin in aMCI and are the most prominent structural changes for those with AD. Alignment differences between aMCI and AD subjects are detected, including notable changes to the hippocampal regions. These findings suggest eigenvector alignment can play a complementary role, alongside established network analytic approaches, to capture how the brain's functional networks develop and adapt when challenged by disease processes such as AD

Neuroanatomical and neuropsychological correlates of resting-state EEG diagnostic features in patients with Alzheimer's disease

Background: In the search for accurate, low cost biomarkers for Alzheimer’s disease (AD) and other dementias, quantitative electroencephalography (EEG) may offer a solution. In a recent multisite study by Cognision, patients with AD were assessed using the Alzheimer Disease Neuroimaging Initiative protocol, plus EEG assessment. The primary objective of the current analysis, was to examine the relationships between a resting-state (rs)EEG feature set (that best discriminated AD patients from controls) and neuroanatomical measures. The second objective was to identify the rsEEG measures that reflected disease staging. Method: Eighty-nine patients with mild AD (MMSE 21-26) were evaluated using a comprehensive neuropsychological assessment battery, 5 minute eyes-open rsEEG, and structural MRI. Correlations (Spearman’s) were assessed between the 35 rsEEG features (that most accurately discriminated the AD patients), neuroanatomical measures (derived using Freesurfer), and neuropsychological test results. Result: Cortical Thickness (CT) measures within the left posterior cingulate and right precuneus were related to alpha features. Beta features were associated with regions including the right entorhinal cortex, middle temporal, supramarginal, lingual, and paracentral cortex, in addition to the anterior cingulate cortex (ACC) and precuneus, bilaterally. Gamma features correlated with regions that included the right ACC and fronto-parietal cortex. Delta features were linked to the left fronto-parietal and right entorhinal cortex. Theta features were associated with the left ACC and visual cortex. In relation to disease staging – Clinical Dementia Rating scores were correlated with gamma features at frontal electrode sites, and with power over frequency bands, delta to beta, at Fz. Alpha features were associated with hippocampal volume (bilaterally), whereas some delta and theta features were linked to left hippocampal volume. Conclusion: These preliminary correlation analyses highlight multiple brain regions that appear to underpin the rsEEG abnormalities that occur due to AD. Given the rich data offered by both rsEEG and by structural MRI, future studies could investigate the combined potential for these techniques to classify the dementias