Peelle J.E.,MRC Cognition and Brain science Unit |
Peelle J.E.,University of Pennsylvania |
Gross J.,University of Glasgow |
Davis M.H.,MRC Cognition and Brain science Unit
Cerebral Cortex | Year: 2013
A growing body of evidence shows that ongoing oscillations in auditory cortex modulate their phase to match the rhythm of temporally regular acoustic stimuli, increasing sensitivity to relevant environmental cues and improving detection accuracy. In the current study, we test the hypothesis that nonsensory information provided by linguistic content enhances phase-locked responses to intelligible speech in the human brain. Sixteen adults listened to meaningful sentences while we recorded neural activity using magnetoencephalography. Stimuli were processed using a noise-vocoding technique to vary intelligibility while keeping the temporal acoustic envelope consistent. We show that the acoustic envelopes of sentences contain most power between 4 and 7 Hz and that it is in this frequency band that phase locking between neural activity and envelopes is strongest. Bilateral oscillatory neural activity phase-locked to unintelligible speech, but this cerebro-acoustic phase locking was enhanced when speech was intelligible. This enhanced phase locking was left lateralized and localized to left temporal cortex. Together, our results demonstrate that entrainment to connected speech does not only depend on acoustic characteristics, but is also affected by listeners' ability to extract linguistic information. This suggests a biological framework for speech comprehension in which acoustic and linguistic cues reciprocally aid in stimulus prediction. © 2012 The Authors.
Gagnepain P.,MRC Cognition and Brain science Unit |
Henson R.N.,MRC Cognition and Brain science Unit |
Davis M.H.,MRC Cognition and Brain science Unit
Current Biology | Year: 2012
Humans can recognize spoken words with unmatched speed and accuracy. Hearing the initial portion of a word such as "formu..." is sufficient for the brain to identify "formula" from the thousands of other words that partially match [1-6]. Two alternative computational accounts propose that partially matching words (1) inhibit each other until a single word is selected ("formula" inhibits "formal" by lexical competition [7-9]) or (2) are used to predict upcoming speech sounds more accurately (segment prediction error is minimal after sequences like "formu..." [10-12]). To distinguish these theories we taught participants novel words (e.g., "formubo") that sound like existing words ("formula") on two successive days [13-16]. Computational simulations show that knowing "formubo" increases lexical competition when hearing "formu...", but reduces segment prediction error. Conversely, when the sounds in "formula" and "formubo" diverge, the reverse is observed. The time course of magnetoencephalographic brain responses in the superior temporal gyrus (STG) is uniquely consistent with a segment prediction account. We propose a predictive coding model of spoken word recognition in which STG neurons represent the difference between predicted and heard speech sounds. This prediction error signal explains the efficiency of human word recognition and simulates neural responses in auditory regions. © 2012 Elsevier Ltd.
Dunn B.D.,MRC Cognition and Brain science Unit
Clinical Psychology and Psychotherapy | Year: 2012
A deficit in the ability to experience pleasure (anhedonia) is one of the core symptoms of depression. However, therapy to date has predominantly focused on understanding elevations in negative emotion experience in depression and relatively neglected ways to reconnect individuals to positive experience. This article reviews current insights into blunted positivity in depression, evaluating evidence that depression leads to disturbances in anticipation (positive emotion experience when approaching a goal or a rewarding stimulus) and consummation (positive emotion experience when attaining a goal or rewarding stimulus), as well as impaired positive emotion recognition. The case is made that existing treatments are only partially effective and that therapy outcomes are likely to be improved by focusing on augmenting positivity, capitalizing on emerging insights from positive affective neuroscience. Existing and emerging therapeutic techniques that may aid the promotion of positivity are critiqued, and some suggestions for future research and clinical practice are outlined. © 2012 John Wiley & Sons, Ltd.
Lawson R.P.,MRC Cognition and Brain science Unit
Journal of vision | Year: 2011
Head direction is a salient cue to the focus of other people's attention. Electrophysiology in macaques has shown head-selective cells in the superior temporal sulcus that are mostly tuned to different directions (up, down, left, right, front, back, etc.). However, there has been no systematic investigation into the visual representation of head direction in both the horizontal (left-right) and vertical (up-down) planes in humans. We addressed whether the coding of head direction is best accounted for by a multichannel system, with distinct pools of cells (or channels) tuned to different head views (i.e., left, right, direct, up, and down), or an opponent-coding system with two broadly tuned pools of cells responding to two extremes (i.e., left-right and up-down) and "direct" represented as the equilibrium state in the system. In a series of four experiments, we carried out two adaptation procedures for which multichannel and opponent coding predict distinct outcomes. The results support multichannel coding of head direction in both the vertical and horizontal axes.
Moore B.C.J.,University of Cambridge |
Gockel H.E.,MRC Cognition and Brain science Unit
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2012
A sequence of sounds may be heard as coming from a single source (called fusion or coherence) or from two or more sources (called fission or stream segregation). Each perceived source is called a'stream'. When the differences between successive sounds are very large, fission nearly always occurs, whereas when the differences are very small, fusion nearly always occurs. When the differencesare intermediate in size, the percept often 'flips' between one stream and multiple streams, a property called 'bistability'. The flips do not generally occur regularly in time. The tendency to hear two streams builds up over time, but can be partially or completely reset by a sudden change in the properties of the sequence or by switches in attention. Stream formation depends partly on the extent to which successive sounds excite different 'channels' in the peripheral auditory system. However, other factors can play a strong role; multiple streams may be heard when successive sounds are presented to the same ear and have essentially identical excitation patterns in the cochlea. Differences between successive sounds in temporal envelope, fundamental frequency, phase spectrum and lateralization can all induce a percept of multiple streams. Regularities in the temporal pattern of elements within a stream can help in stabilizing that stream. © 2012 The Royal Society.
Holmes J.,MRC Cognition and Brain science Unit
Current Biology | Year: 2011
A recent study shows that a relatively short period of cognitive training can improve infants' ability to sustain and flexibly deploy attention. Thus, it appears important aspects of cognition can be modified using 'brain-training' techniques at an early age. © 2011 Elsevier Ltd. All rights reserved.
Agency: GTR | Branch: MRC | Program: | Phase: Intramural | Award Amount: 1.16M | Year: 2012
Even the best treatments in mental health need improvement and many areas lack effective interventions. Cognitive science offers methods to develop new and more effective treatments via increasing our understanding of basic psychological processes. One relatively neglected area concerns mental imagery (e.g. seeing in the mind’s eye, hearing in the mind’s ear) as psychological therapies tend to focus on verbal language. However, mental imagery is implicated in many psychological disorders and has a more powerful impact on emotion than its verbal counterpart (thinking in words). Mental imagery therefore presents exciting opportunities for mental health treatment innovation. The broad aims of our research are: To use cognitive science to investigate the mechanisms underlying psychological disorders, with a particular focus on mental imagery. To use findings from this basic research to develop more focussed and effective psychological therapies. To develop innovative methods to target key cognitive processes when these become problematic in psychological disorders whether via face-to-face therapy (e.g. cognitive behaviour therapy), computers (e.g. cognitive bias modification), or simple cognitive tasks (e.g. working memory interference). Our research takes an interdisciplinary approach including psychology (basic and clinical) and psychiatry, cognitive science and neuroscience. We investigate psychological processes along the continuum of experience from wellbeing to distress. There is a clinical focus on three clinical areas: PTS (Post-traumatic Stress), Depression, and Bipolar Disorder (commonly called manic-depression).
Agency: GTR | Branch: MRC | Program: | Phase: Intramural | Award Amount: 1.76M | Year: 2011
We are investigating important cognitive abilities that have a significant practical aspect of our everyday lives, and can be impaired both in childhood and in later life as a consequence of changes in the brain. This programme focuses in particular on working memory, the system that temporary the necessary temporary storage of information necessary to guide us through our ongoing cognitive and physical activities. We explore the specific cognitive processes and their associated brain structures in children with poor working memory skills; these include children with dyslexia, language impairments, and ADHD. We are investigating whether intensive training can be effective in overcoming memory and related impairments. This research is likely to have practical value in the development of new methods for identifying working memory impairments, and also of therapeutic techniques for overcoming cognitive deficits that are relevant to both clinical and educational practice.
Agency: GTR | Branch: MRC | Program: | Phase: Intramural | Award Amount: 696.41K | Year: 2012
Over 80% of children with poor working memory capacity (those falling into the bottom 10% for their age) have significantly poor reading or mathematics, and usually both. Many of these children suffer from symptoms of inattention, and in many respects have a cognitive profile similar to that of children with a formal diagnosis of ADHD. This research programme attempts to understand the core mechanism/s implicated in this class of disorder, and whether these mechanisms can be boosted through targeted intervention. The programme uses non-invasive neuroimaging techniques that can measure neural activity in real time, to explore the connections through which different parts of the brain work together. We know already from research in adults and animals that these functional connections are very important in both attention and working memory. In addition to testing the strength of these connections (in particular between areas in frontal, parietal and sensory brain areas) we aim to test whether we can boost these connections with targeted cognitive training. The ultimate goal of this programme is to understand the mechanisms that underpin the cognitive and behavioural problems of these children, and to modify these mechanisms with the hope of reducing these difficulties.
Agency: GTR | Branch: MRC | Program: | Phase: Intramural | Award Amount: 41.37K | Year: 2015
Understanding the bill at a restaurant, solving a crossword puzzle or planning your shopping trip are examples of how we use high-level cognitive abilities known as ‘executive functions’. These abilities are some of the last cognitive abilities to develop in adolescence and the first to decline as we age. They are important for many outcomes in life, including success at school, how well you do at work, and whether you are able to live independently into old age. They even have an impact on how long we live and the state of our mental health. Because more people in the developed world are living into old age, there is a need for people to function healthily for longer. Yet, despite the vital role that these aspects of human cognition play in our daily life, we do not fully understand how changes in brain structure and function support executive functions across the lifespan. In this research programme I use innovative statistical techniques in large, longitudinal cohort studies to better understand how changing brains underlie changing minds.