Re-Entraining the Brain: Exploring and Exploiting Oscillatory Models of Speech Perception in Wernicke's Aphasia

为了理解口语，我们需要在耳朵里听到它，然后分析声音，从大脑中提取单词。这个过程被称为语音感知。只有在准确的言语感知之后，我们才能分析这些词的语法和意义。中风损害了支持言语知觉的区域，导致理解口语的严重障碍。这阻止了人们与朋友和家人的联系，切断了人们与工作和休闲活动的联系。我们的长期目标是改善对这些人的治疗，让他们过上更完整和更有成就感的生活。一种著名的言语感知理论认为，当我们听到声音时，我们的脑细胞开始与声音的节奏同步地启动，这有助于我们弄清楚我们听到的是什么。这与跟着你正在听的歌曲的节奏敲击没有什么不同。大脑活动与语音中的音节模式同步，帮助我们识别我们正在听到的单词。我们假设，中风患者的言语感知障碍可能是由于这种同步化的失败造成的。为了测试这一点，我们将测量中风后有言语感知问题的人的大脑与语言的同步性，这种情况被称为韦尼克失语症。我们将比较没有中风的人和大脑不同部位中风的人的能力，看看问题是否与韦尼克失语症有关。我们还会将大脑的同步化程度与语言测试和日常生活中的理解障碍程度进行比较，以了解对人们的影响。令人惊讶的是，在韦尼克失语症中，言语感知有时是准确的，尽管一些言语感知大脑结构丢失了。我们将调查大脑的哪些部分做出反应，以及当言语感知更准确和不准确时，大脑不同部分是如何协同工作的。这一点很重要，因为我们想更频繁地帮助大脑以最有效的方式工作。我们可以利用这些信息来尝试并通过电刺激来改善言语感知。对没有中风的人的研究表明，听简单的有节奏的声音可以改变大脑与随后的声音同步的方式。当大脑被施加到头皮上的非常小的电流刺激时，也会发生这种情况，这已经被证明可以帮助人们更好地听到声音和理解语言。我们假设，我们可以使用这些方法来改善韦尼克失语症患者的言语感知和语言理解。我们的试点数据表明这是真的--当我们在讲话前播放有节奏的声音时，韦尼克失语症患者更能听到语音之间的差异。这是有希望的，因为这种能力对理解语音至关重要。我们还将探索为什么有节奏的声音通过测量大脑活动来改善言语感知，看看当我们试图增强同步性时，大脑是否会做出更典型的反应。该联谊会的最后一项研究将使用电流刺激来帮助大脑活动与语言同步。我们将利用我们之前的结果来计算出大脑的哪些部分对语音做出最有效的反应，并刺激这些区域，然后衡量人们是否能够更好地理解电刺激所说的句子。如果我们在这项研究中找到支持这些假设的证据，我们将通过加强大脑同步化，找到治疗中风后言语感知和语言理解障碍的新方法。我们还将通过观察对同步大脑活动的影响，找到衡量我们的疗法如何奏效的新方法。

To understand spoken language we need to hear it at the ear and then analyse the sounds and extract the words in the brain. This process is known as speech perception. It is only after accurate speech perception that we can analyse the grammar and meaning of those words. Strokes which damage regions supporting speech perception cause a severely disabling impairment in understanding spoken language. This stops people from connecting with their friends and family and cuts people off from work and leisure activities. Our long-term goal is to improve treatments for these individuals, allowing them to lead a more complete and fulfilling life. One prominent theory of speech perception argues that when we hear sounds our brain cells start to fire in time (synchronise) with the rhythm of the sound, and this helps us to work out what we are hearing. This is not unlike tapping along to the rhythm of a song you are listening to. Brain activity synchronises with the pattern of syllables in speech and helps us to identify the words we are hearing. We hypothesise that speech perception impairments in people with strokes may arise from a failure of this synchronisation. To test this, we will measure brain synchronisation to speech in people with speech perception problems after stroke, a condition known as Wernicke's aphasia. We will compare the abilities of people without strokes and of people with strokes in different parts of their brain to see if problems are specific to Wernicke's aphasia. We will also compare the degree of brain synchronisation to the degree of comprehension impairment on language tests and in daily life to understand the impact on people. Surprisingly, speech perception is sometimes accurate in Wernicke's aphasia, even though some speech perception brain structures are lost. We will investigate which parts of the brain are responding and how different parts of the brain work together when speech perception is more accurate and when it is inaccurate. This is important because we want to help the brain to work in the most effective way more often. We can use this information to try and improve speech perception using electrical stimulation. Research in people without strokes shows that listening to simple rhythmic sounds can change the way the brain synchronises with the sounds that follow. This also happens when the brain is stimulated with a very small electrical current applied to the scalp, and this has been shown to help people hear sounds and understand speech better. We hypothesise that we can use these methods to improve speech perception and language comprehension in people with Wernicke's aphasia. Our pilot data suggests that this is true - when we played rhythmic sounds before speech, people with Wernicke's aphasia were better able to hear the difference between the speech sounds. This is promising because this ability is crucial for understanding speech. We will also explore why rhythmic sounds improve speech perception by measuring brain activity to see whether the brain responds more "typically" when we try to enhance synchronisation. The last study in the fellowship will use electrical current stimulation to help to synchronise brain activity to speech. We will use our previous results to work out which parts of the brain respond most effectively to speech and stimulate those areas, then measure whether people are better able to understand spoken sentences with electrical stimulation. If we find evidence for the hypotheses in this fellowship, we will have identified new ways to treat speech perception and language comprehension impairments after stroke, by enhancing brain synchronisation. We will also have found new ways of measuring how our therapies are working, by looking at the effects on synchronised brain activity.