2008年9月一期的愛思唯爾期刊《大腦皮層》（Cortex）最近刊登了倫敦精神病學(xué)研究所的一項(xiàng)最新研究，研究對于人們出現(xiàn)的幻覺進(jìn)行了研究，結(jié)合腦功能成像方法來捕捉產(chǎn)生幻覺瞬間大腦區(qū)域發(fā)生的變化，繼而揭開產(chǎn)生的幻覺的原因。
幻覺是一種虛幻的表象,，本來并不存在的某種事物，人們有時(shí)卻感知它的存在。正常人偶爾會(huì)可出現(xiàn)幻覺,，這往往與心理有密切關(guān)系，此外在受到突然強(qiáng)烈的刺激下亦可出現(xiàn)幻覺,。但是另外一種持續(xù)時(shí)間較長,，與心情無密切關(guān)系的幻覺，往往見于精神分裂癥患者,。對于幻覺的研究目前知之甚少,，因?yàn)榛糜X的產(chǎn)生具有不可預(yù)測性，同時(shí)往往瞬間發(fā)生,。所以很難知道大腦出現(xiàn)幻覺時(shí)候的變化,。為了研究產(chǎn)生幻覺時(shí)候腦部區(qū)域的變化,，研究人員采用了特別的方法，比如使用閃爍的燈光,，生動(dòng)的顏色等,，刺激人產(chǎn)生幻覺，同時(shí)結(jié)合使用的腦功能成像方法來捕捉產(chǎn)生幻覺瞬間大腦區(qū)域發(fā)生的變化,，繼而揭開產(chǎn)生的幻覺的原因,。
研究發(fā)現(xiàn)，幻覺出現(xiàn)時(shí)候,，腦內(nèi)視覺系統(tǒng)有著明顯地變化,。研究人員認(rèn)為視覺系統(tǒng)在傳遞信號中，由于外界干擾等因素,，這部分信號在向大腦視覺系統(tǒng)傳輸中出現(xiàn)了短暫的“中斷”,，這使得人類的大腦對于處理信息發(fā)生了紊亂，繼而導(dǎo)致了幻覺的產(chǎn)生,。（生物谷Bioon.com）
生物谷推薦原始出處：
Cortex,，doi:10.1016/j.cortex.2008.04.005，Dominic H. ffytche
The hodology of hallucinations
Dominic H. ffytche,
Centre for Neuroimaging Sciences, Institute of Psychiatry, De Crespigny Park, London, UK
Abstract
The hodotopic framework is a recent revision of Geschwind's disconnection paradigm incorporating advances in functional and white matter imaging. Its intention is to help clinico-pathological correlations across a range of neurological and psychiatric conditions and generate novel research questions. Here I consider hallucinations within this framework. The paper is divided into three parts. The first reviews the auditory and visual hallucination literature from the dual perspectives of dysfunction localised to specific brain regions (topological) and dysfunction related to connections between brain regions (hodological), combining evidence from tractography, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) studies. Patients prone to hallucinations have complex, task-specific hodological abnormalities that persist between hallucination episodes. During hallucinations, topological increases in activity are found whose location defines hallucination content and modality. Whether these activity increases are accompanied by transient hodological change is unclear. The second part of the paper addresses this issue in EEG and fMRI studies of a 200-year-old paradigm. Photic stimulation within a specific frequency and luminance range induces hallucinations of geometrical patterns, colours and motion in normal subjects. By comparing hallucination-inducing with control stimulation, topological activity increases were identified in visual areas whose specialisations matched the induced hallucination contents. During hallucinations, fMRI connectivity between LGN and cortex changed from a positive to negative relationship while EEG connectivity between occipital and other brain regions increased. The complex and dynamic topological and hodological changes during induced hallucinations are consistent with a shift in thalamocortical circuitry from tonic to burst mode and may have direct relevance to the Charles Bonnet Syndrome. The third part of the paper considers the relevance of the finding to other disorders, examines the strengths and limitations of our current imaging approaches to connectivity and looks to future developments in the field.
