Outline
- Abstract
- Keywords
- Introduction
- Materials and Methods
- Vibrotactile Stimulation Tasks
- Image Acquisition, Preprocessing, and Atlas Registration
- Statistical Analyses
- Results
- Task Performance During Imaging
- Group and Task T-Maps
- Effect of Task Difficulty
- Task Contrasts
- Prefrontal Cortex
- Intraparietal Sulcal Cortex
- Occipital Cortex
- Group Contrasts
- Occipital Cortex
- Intraparietal Sulcal Cortex
- Prefrontal Cortex
- Parietal Cortex
- Premotor Cortex
- Discussion
- Activity in Occipital Cortex
- Dorsolateral Frontal Cortex and Wm
- Attention Effects
- Conclusions
- References
رئوس مطالب
- چکیده
- کلیدواژه ها
- مقدمه
- مواد و روش ها
- وظایف تحریک ویبرو تاکتیل
- اکتساب تصویر ، پیش پردازش، و ثبت اطلس
- تجزیه و تحلیل آماری
- نتایج
- عملکرد وظیفه در طول تصویربرداری
- نگاشت های t گروه و وظیفه
- اثر سختی کار
- اختلافات وظیفه
- قشر جلو مغزی
- قشر sulcal Intraparietal
- قشر پس سری
- تضاد گروه
- قشر پس سری
- قشر sulcal Intraparietal
- قشر جلو مغزی
- قشر آهیانه ای
- قشر پیش حرکتی
- بحث
- فعالیت در قشر پس سری
- قشر قدامی خلفی جانبی و WM
- اثرات توجه
- نتیجه گیری
Abstract
In blind, occipital cortex showed robust activation to non visual stimuli in many prior functional neuroimaging studies. The cognitive processes represented by these activations are not fully determined, although a verbal recognition memory role has been demonstrated. In congenitally blind and sighted (10 per group), we contrasted responses to a vibrotactile one‐back frequency retention task with 5‐s delays and a vibrotactile amplitude‐change task; both tasks involved the same vibration parameters. The one‐back paradigm required continuous updating for working memory (WM). Findings in both groups confirmed roles in WM for right hemisphere dorsolateral prefrontal (DLPFC) and dorsal/ventral attention components of posterior parietal cortex. Negative findings in bilateral ventrolateral prefrontal cortex suggested task performance without subvocalization. In bilateral occipital cortex, blind showed comparable positive responses to both tasks, whereas WM evoked large negative responses in sighted. Greater utilization of attention resources in blind were suggested as causing larger responses in dorsal and ventral attention systems, right DLPFC, and persistent responses across delays between trials in somatosensory and premotor cortex. In sighted, responses in somatosensory and premotor areas showed iterated peaks matched to stimulation trial intervals. The findings in occipital cortex of blind suggest that tactile activations do not represent cognitive operations for non verbal WM task. However, these data suggest a role in sensory processing for tactile information in blind that parallels a similar contribution for visual stimuli in occipital cortex of sighted.
Keywords: human occipital cortex - magnetic resonance imaging - torelyuchConclusions
The current results showed no disproportionate utilization of any part of occipital cortex in EB for vibrotactile WM. The vibrotactile stimuli lacked verbal, spatial, dimensional, and motion parameters and yet overwhelmingly activated several multisensory, supramodal occipital regions previously studied using more diverse tactile parameters. Most parsimoniously, occipital cortex in EB has a significant role in tactile sensory processing irrespective of its cognitive context. Consequently, temporary [Cohen et al., 1997, 1999] or permanent [Hamilton et al., 2000] lesions of occipital cortex in EB might disrupt tactile sensory processing and in so doing cause Braille agnosia. In NS, similar occipital cortex lesions would interrupt visual processing and thereby disrupt reading text. Because the tactile tasks lacked a verbal component, the present study does not discount prior evidence of blindness induced adaptations for word recognition memory in left striate cortex. Similarly, because the vibrotactile stimuli did not involve spatial or multidimensional object parameters, this study does not argue against a supramodal role for multisensory extrastriate regions in spatial or object cognition. However, deserving further scrutiny is persistent evidence of larger right occipital responses to tactile stimulation; particularly puzzling was activity ipsilateral to the stimulated hand. Additionally, other studies have shown that EB have learned skills for superior attentional performance. The larger responses in frontal and parietal regions particularly involved in ‘‘attention to memory’’ possibly resulted from these attention skills in EB. Better attention to tactile inputs might also underlie the sustained delayinterval activity between stimulation trials in somatosensory and premotor cortex in EB participants.