FMRI Reveal Large-scale Visual Network In Minimally Conscious State Patients

ObjectiveMinimally conscious state(MCS) is characterized by inconsistent but clearly discernible behavioral evidence of consciousness and can be distinguished from coma and VS by documenting the presence of specific behavioral features not found in either of these conditions. To test the hypothesis the MCS patients retain large-scale visual network, and further to explore whether passive visual picture presenting will elicit visual network or not, especially for familiar family pictures with strong emotion valenc, which MCS patients were very familiar with before severely brain injury.MethodsVisual pictures were divided into three groups. The first was family picture group, these pictures were patient's intimiate family members and his own pictures which the patient was very familiar with before injury. The other two groups were high-stimulating picture and medium-stimulating picture which were selected from International Affective Picture System provided by NIMH Center for the Study of Emotion and Attention in the University of Florida. In high-stimulating picture group, Average affective valenc was 7.22 score, average arousal 6.25 score. In medium-stimulating picture group, average affective valenc was 4.65 score, average arousal 2. 45 score.The first part:Thirty heathy volunteers were involved. Thirty pictures were selected form IAPS, divided into high-stimulating and medium-stimulating group according to affective valence and arousal. These pictures were rescored in volunteers according the methods which were introduced in NIMH. For these standard pictures, we compared the standard affective, arousal and dominance score with volunteers'. What's more, wecompared the affective and arousal scores in volunteers.The second part:Ten heathy volunteers were recruited .With fMRI , we explored the feasibility and reliability to research the visual network with the high-stimulating and medium-stimulating pictures presenting.The third part:Nine MCS patients and ten healthy volunteers were recruited, all man without history of neurologic disorders, psychological or other chronic disease. MCS patients were mainly just recover from long coma for severly brain trauma or spontaneous brain bleeding.During fMRI scan, Block Design was selected, pictures were edited by Eprime software and presented by SAMRTEC visual system. Each scan was three minutes, three groupe pictures were presented randomly. All data were analyzed by AFNI software, then activation map and BOLD signal change were got.ResultsThe first part:Scores were no distinct different in affective valence, arousal and dominance between volunteers and standard group. Within volunteers, affective valence and dominance were different distinctly between high-stimulating pictures with medium-stimulating's.The second part:During high-stimulating and medium-stimulating pictures presenting in volunteers, activation were elicited in primary visual occipital cortex, second visual cortex and associative regions including temporal cortex, fulsiform gyrus, parietal cortex, amygdala, orbitofrontal and prefrontal cortex. The activation was relatively higher during high-stimulating picture presenting.Compared with above two group pictures, family-pictures also elicited similar activation in brain. No distint activation differencebetween family-picture and medium-stimulating picture group.The third part:Three group pictures presenting in control volunteers, activation were elicited in primary visual occipital cortex, second visual cortex and associative regions including temporal cortex, fulsiform gyrus, parietal cortex, amygdala , orbitofrontal and prefrontal cortex.The activation was relatively higher during high-stimulating picture presenting than family-picture and medium-stimulating pictures passive stimulating. No distint activation difference between family-picture and medium-stimulating picture group.For MCS patients, occipital activation were found in 5 cases during high-stimulating picture presenting, 7 cases for family-picture and medium-stimulating picture presenting respectively, which means patients had seen the presented pictures. Including occipital cortex, temporal cortex, fulsiform gyrus, parietal cortex, amygdala, orbitofrontal and prefrontal cortex, Visual network were totally activated in two cases during high-stimulating picture presenting, three cases in medium-stimulatin picture group, and six cases in family-picture group. Stimulus-independent activity were found in MCS patients who had no activation in occipial cortex during passive picture presenting.For the MCS patients who had occipital activation during passive picture stimulation, mean activation volume in temporal, prefrontal and total brain were much lower than in normal control volunteers group, especially during high-stimulatig picture and medium-stimulating piture presentation. Unlike in normal control volunteers group, mean activation volume in temporal, prefrontal and total brain were much higher in family-stimulating picture group than in high-stimulating picture and medium-stimulating picture group for MCS patients. Like in normal control volunteers group, BOLD signal change in amygdala was relative higher in high-stimulating picture group than in family-stimulating and medium-stimulating picture group, although decreased a little compared wih normal volunteers.Activation talairach coordinate in the same brain region wasdifferent greatly for different MCS patients. At the same time, activation region and volume were different greatly during three different picture stimulation for the same MCS patient.ConclusionThirty pictures form IAPS were adapted to Chinese as emotional visual stimulating pictures.It was reliabe and viable to investigate the visual network with family pictures and IAPS pictures in Chinese man.From fMRI activation map, visual attention and visual conscious state were inconsistent and intermittent in MCS patients.MCS patients can still keep intact visual network, including occipital cortex, temporalcortex, fulsiform gyrus, parietalcortex, amygdala, prefrontal and orbitofrontal cortex, which can be activated totally by passive picture presenting.Passive picture stimulation , especially the family strong emotional pictures which patients were very familiar with before coma, can elicit conscious brain activity, which may beneficial for the recovery of brain function...