MRC Cognition and Brain science Unit
MRC Cognition and Brain science Unit
Evans S.,MRC Cognition and Brain science Unit |
Evans S.,University College London |
Davis M.H.,MRC Cognition and Brain science Unit
Cerebral Cortex | Year: 2015
How humans extract the identity of speech sounds from highly variable acoustic signals remains unclear. Here, we use searchlight representational similarity analysis (RSA) to localize and characterize neural representations of syllables at different levels of the hierarchically organized temporo-frontal pathways for speech perception.We asked participants to listen to spoken syllables that differed considerably in their surface acoustic form by changing speaker and degrading surface acoustics using noise-vocoding and sine wave synthesis while we recorded neural responses with functional magnetic resonance imaging.We found evidence for a graded hierarchy of abstraction across the brain. At the peak of the hierarchy, neural representations in somatomotor cortex encoded syllable identity but not surface acoustic form, at the base of the hierarchy, primary auditory cortex showed the reverse. In contrast, bilateral temporal cortex exhibited an intermediate response, encoding both syllable identity and the surface acoustic form of speech. Regions of somatomotor cortex associated with encoding syllable identity in perception were also engaged when producing the same syllables in a separate session. These findings are consistent with a hierarchical account of how variable acoustic signals are transformed into abstract representations of the identity of speech sounds. © 2015 The Author.
Grahn J.A.,University of Western Ontario |
Rowe J.B.,MRC Cognition and Brain science Unit |
Rowe J.B.,University of Cambridge
Cerebral Cortex | Year: 2013
Perception of temporal patterns is critical for speech, movement, and music. In the auditory domain, perception of a regular pulse, or beat, within a sequence of temporal intervals is associated with basal ganglia activity. Two alternative accounts of this striatal activity are possible: "searching" for temporal regularity in early stimulus processing stages or "prediction' of the timing of future tones after the beat is found (relying on continuation of an internally generated beat). To resolve between these accounts, we used functional magnetic resonance imaging (fMRI) to investigate different stages of beat perception. Participants heard a series of beat and nonbeat (irregular) monotone sequences. For each sequence, the preceding sequence provided a temporal beat context for the following sequence. Beat sequences were preceded by nonbeat sequences, requiring the beat to be found anew ("beat finding" condition), or by beat sequences with the same beat rate ("beat continuation"), or a different rate ("beat adjustment"). Detection of regularity is highest during beat finding, whereas generation and prediction are highest during beat continuation. We found the greatest striatal activity for beat continuation, less for beat adjustment, and the least for beat finding. Thus, the basal ganglia's response profile suggests a role in beat prediction, not in beat finding. © 2012 The Authors 2012. Published by Oxford University Press.
Levy B.J.,University of San Francisco |
Anderson M.C.,MRC Cognition and Brain science Unit
Journal of Neuroscience | Year: 2012
Understanding the neural basis of conscious experience and its regulation are fundamental goals of science. While recent research has made substantial progress in identifying the neural correlates of conscious experiences, it remains unclear how individuals exert control over the contents of awareness. In particular, can a memory that has entered the aware state be purged from consciousness if it is not currently desired? Here we tracked the correlates of consciousness in humans using functional magnetic resonance imaging and demonstrated the involvement of a downregulation mechanism that purges contents from conscious awareness. When individuals tried to prevent the retrieval of a memory in response to reminders, hippocampal activity was reduced, as previously established. Crucially, using trial-by-trial reports of phenomenal awareness, we found that this reduction of hippocampal activation was specifically associated with moments when a memory involuntarily intruded into conscious awareness and needed to be purged. This downregulation of activity during memory intrusions appears to disrupt momentary awareness of unwanted contents and, importantly, predicts impaired recall of the memory on later tests. These results tie the voluntary control of phenomenal awareness to observable changes in neural activity linked to awareness, and so provide a neurobiological model for guiding inquiry into the physical foundations of control over consciousness. © 2012 the authors.
Ralph M.A.L.,University of Manchester |
Jefferies E.,University of York |
Patterson K.,MRC Cognition and Brain science Unit |
Patterson K.,University of Cambridge |
Rogers T.T.,University of Wisconsin - Madison
Nature Reviews Neuroscience | Year: 2016
Semantic cognition refers to our ability to use, manipulate and generalize knowledge that is acquired over the lifespan to support innumerable verbal and non-verbal behaviours. This Review summarizes key findings and issues arising from a decade of research into the neurocognitive and neurocomputational underpinnings of this ability, leading to a new framework that we term controlled semantic cognition (CSC). CSC offers solutions to long-standing queries in philosophy and cognitive science, and yields a convergent framework for understanding the neural and computational bases of healthy semantic cognition and its dysfunction in brain disorders. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Duncan J.,MRC Cognition and Brain science Unit |
Duncan J.,University of Oxford
Neuron | Year: 2013
Cognition is organized in a structured series of attentional episodes, allowing complex problems to be addressed through solution of simpler subproblems. A "multiple-demand" (MD) system of frontal and parietal cortex is active in many different kinds of tasks, and using data from neuroimaging, electrophysiology, neuropsychology, and cognitive studies of intelligence, I propose a core role for MD regions in assembly of the attentional episode. Monkey and human data show dynamic neural coding of attended information across multiple MD regions, with rapid communication within and between regions. Neuropsychological and imaging data link MD function to fluid intelligence, explaining some but not all "executive" deficits after frontal lobe lesions. Cognitive studies link fluid intelligence to goal neglect, and the problem of dividing complex task requirements into focused parts. Like the innate releasing mechanism of ethology, I suggest that construction of the attentional episode provides a core organizational principle for complex, adaptive cognition.
Benoit R.G.,MRC Cognition and Brain science Unit |
Anderson M.C.,MRC Cognition and Brain science Unit
Neuron | Year: 2012
Reminders of the past can trigger the recollection of events that one would rather forget. Here, using fMRI, we demonstrate two distinct neural mechanisms that foster the intentional forgetting of such unwanted memories. Both mechanisms impair long-term retention by limiting momentary awareness of the memories, yet they operate in opposite ways. One mechanism, direct suppression, disengages episodic retrieval through the systemic inhibition of hippocampal processing that originates from right dorsolateral prefrontal cortex (PFC). The opposite mechanism, thought substitution, instead engages retrieval processes to occupy the limited focus of awareness with a substitute memory. It is mediated by interactions between left caudal and midventrolateral PFC that support the selective retrieval of substitutes in the context of prepotent, unwanted memories. These findings suggest that we are not at the mercy of passive forgetting; rather, our memories can be shaped by two opposite mechanisms of mnemonic control.
Pulvermuller F.,MRC Cognition and Brain science Unit
Journal of Neurolinguistics | Year: 2012
Which types of nerve cell circuits enable humans to use and understand meaningful signs and words? Philosophers were the first to point out that the arbitrary links between signs and their meanings differ fundamentally between semantic word types. Neuroscience provided evidence that semantic kinds do indeed matter: Brain diseases affect specific semantic categories and leave others relatively intact. Patterns of precisely timed brain activation in specific areas of cortex reflect the comprehension of words with specific semantic features. The classic referential link between words and the objects they are used to speak about can be understood as a result of associative learning driven by correlated neuronal activity in perisylvian language areas and sensory, especially higher visual but also olfactory, somatosensory and auditory, areas. However, the meaning of words used to speak about actions calls for a different account. For learning their meaning, specific action and interaction contexts are critical, and neuronal links between language and action systems of the human brain likely store such action-semantic information. In fact, after learning, the action system is sparked when such words and utterances are being used or understood, and, correspondingly, functional changes in the brain's motor system influence the recognition of action-related expressions. These results show that language is "woven into action" at the level of the brain. Word-object, word-action and word-word contexts are discussed in view of further facets of semantics and their brain basis, including emotional-affective, abstract and combinatorial aspects of meaning. All of these aspects and corresponding neuronal circuit types interact in the processing of the meaning of words and sentences in the human mind and brain. © 2011 Elsevier Ltd.
Duncan J.,MRC Cognition and Brain science Unit
Trends in Cognitive Sciences | Year: 2010
A common or multiple-demand (MD) pattern of frontal and parietal activity is associated with diverse cognitive demands, and with standard tests of fluid intelligence. In intelligent behaviour, goals are achieved by assembling a series of sub-tasks, creating structured mental programs. Single cell and functional magnetic resonance imaging (fMRI) data indicate a key role for MD cortex in defining and controlling the parts of such programs, with focus on the specific content of a current cognitive operation, rapid reorganization as mental focus is changed, and robust separation of successive task steps. Resembling the structured problem-solving of symbolic artificial intelligence, the mental programs of MD cortex appear central to intelligent thought and action. © 2010 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: 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.