Learning and plasticity in the human brain

人脑的学习和可塑性

• 批准号: 8556969
• 负责人: Christopher Baker
• 金额: $ 35.15万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8556969
• 关键词: Adult; Amputation; Amputees; Blindness; Brain; Brain Part; Brain region; Characteristics; Conflict (Psychology); Decision Making; Development; Disease; Elderly; Esthesia; Feeling; Functional Magnetic Resonance Imaging; Functional disorder; Goals; Human; Impairment; Injury; Judgment; Lead; Learning; Limb structure; Macular degeneration; Measures; Modeling; Monitor; Motion; Motor Cortex; Nature; Nervous System Trauma; Nervous system structure; Pain; Participant; Patients; Perceptual distortions; Performance; Phantom Limb Pain; Population; Prevalence; Process; Recruitment Activity; Rehabilitation therapy; Reporting; Research; Retina; Retinal; Somatosensory Cortex; Syndrome; Tactile; Thick; Time; Trauma; Traumatic Brain Injury; Veterans; Vision; Visual Cortex; Visual Cortex Disorder; Visual Fields; Visual Hallucination; Visual Motion; War; Work; autism spectrum disorder; experience; insight; interest; relating to nervous system; response; retinal damage; sample fixation; somatosensory; theories; visual process; visual processing; visual stimulus

The primary goals of this research are i) to establish the changes in brain processing arising from nervous system damage or dysfunction, ii) to understand how brain plasticity contributes to these changes, and iii) to determine how learning may ameliorate the negative consequences of such changes. Over the past year we have continued to focus primarily on plasticity following the loss of input to particular regions of the brain, including visual and somatosensory cortex. i) Loss of visual input. People with macular degeneration lose central vision due to retinal damage. But what happens to the parts of the brain that are specifically involved in processing central visual stimuli? Using fMRI, we have previously shown that the parts of the brain deprived of input start to respond to visual stimuli in other regions of the visual field, as if they are taking on new function. We have referred to this as reorganization of visual processing. We have further demonstrated that such reorganization is dependent on complete loss of central vision, is not specific to the part of the retina used for fixation in people with macular degeneration (often referred to as the Preferred Retinal Locus, or PRL), and may lead to perceptual distortions. We are currently investigating the impact of vision loss in macular degeneration on cortical thickness. In some developmental visual disorders, the cortex has been reported to be thinner than in healthy control participants, but it is unknown whether such structural changes also occur when the vision loss happens in adulthood. ii) Loss of somatosensory input. Following limb amputation, over 90% of people report phantom sensations in their missing limb, often painful sensations (Phantom Limb Pain, or PLP). One current theory suggests that PLP is a direct result of cortical reorganization, an example of maladaptive plasticity. Mirror therapy has been used as a treatment for PLP. During this therapy, patients move their intact limb while looking in a mirror, making it seem as if their missing limb is moving. We are currently investigating the neural consequences of amputation and the impact of mirror therapy on brain activity over time. We are continuing to recruit unilateral limb amputees and monitoring brain activity with fMRI over a period of four weeks while the amputees undergo mirror therapy. We are trying to establish whether the presence of PLP correlates with cortical reorganization in the somatosensory and motor cortex (similar to that observed in our participants with macular degeneration) and whether the mirror therapy works by reducing the extent of cortical reorganization. In addition, we have been investigating motion processing and decision-making in Autism Spectrum Disorders (ASD), processes that are supported by a well-characteristic brain network. Previous studies have reported conflicting results with some studies finding impaired motion processing in ASD and other finding no impairment. By varying the time allowed to make judgments, we find that motion processing in ASD is impaired, but only at short durations. Further, this deficit in performance is reflected in the activity of brain regions involved in visual motion processing, with reduced responses in autistic compared with control participants. Establishing the nature, degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies following injury or dysfunction in the nervous system.

本研究的主要目标是：(1)确定神经系统损伤或功能障碍引起的大脑处理变化；(2)了解大脑可塑性如何促成这些变化；(3)确定学习如何改善这些变化的负面影响。在过去的一年里，我们继续主要关注大脑特定区域（包括视觉和体感皮层）输入丢失后的可塑性。