The Journal of neuroscience : the official journal of the Society for Neuroscience, 2011
These can result in a failure to maintain consistent goal-directed behavior. A predominantly righ... more These can result in a failure to maintain consistent goal-directed behavior. A predominantly right-lateralized frontoparietal network is often engaged during attentionally demanding tasks. However, lapses of attention have also been associated with increases in activation within the default mode network (DMN). Here, we study TBI patients with sustained attention impairment, defined on the basis of the consistency of their behavioral performance over time. We show that sustained attention impairments in patients are associated with an increase in DMN activation, particularly within the precuneus and posterior cingulate cortex. Furthermore, the interaction of the precuneus with the rest of the DMN at the start of the task, i.e., its functional connectivity, predicts which patients go on to show impairments of attention. Importantly, this predictive information is present before any behavioral evidence of sustained attention impairment, and the relationship is also found in a subgroup of patients without focal brain damage. TBI often results in diffuse axonal injury, which produces cognitive impairment by disconnecting nodes in distributed brain networks. Using diffusion tensor imaging, we demonstrate that structural disconnection within the DMN also correlates with the level of sustained attention. These results show that abnormalities in DMN function are a sensitive marker of impairments of attention and suggest that changes in connectivity within the DMN are central to the development of attentional impairment after TBI.
Abstract This review considers speaking in a second language from the perspective of motor–sensor... more Abstract This review considers speaking in a second language from the perspective of motor–sensory control. Previous studies relating brain function to the prior acquisition of two or more languages (neurobilingualism) have investigated the differential demands made on linguistic representations and processes, and the role of domain-general cognitive control systems when speakers switch between languages.
Using functional MRI, we investigated whether auditory processing of both speech and meaningful n... more Using functional MRI, we investigated whether auditory processing of both speech and meaningful non-linguistic environmental sounds in superior and middle temporal cortex relies on a complex and spatially distributed neural system. We found that evidence for spatially distributed processing of speech and environmental sounds in a substantial extent of temporal cortices. Most importantly, regions previously reported as selective for speech over environmental sounds also contained distributed information.
Abstract One functional anatomical model of reading, drawing on human neuropsychological and neur... more Abstract One functional anatomical model of reading, drawing on human neuropsychological and neuroimaging data, proposes that a region in left ventral occipitotemporal cortex (vOT) becomes, through experience, specialized for written word perception. We tested this hypothesis by presenting numbers in orthographical and digital form with two task demands, phonological and numerical.
Abstract Regions of the human temporal lobe show greater activation for speech than for other sou... more Abstract Regions of the human temporal lobe show greater activation for speech than for other sounds. These differences may reflect intrinsically specialized domain-specific adaptations for processing speech, or they may be driven by the significant expertise we have in listening to the speech signal. To test the expertise hypothesis, we used a video-game-based paradigm that tacitly trained listeners to categorize acoustically complex, artificial nonlinguistic sounds.
Abstract We investigate the method of power indices to study voting power of members of a legisla... more Abstract We investigate the method of power indices to study voting power of members of a legislature that has voting blocs. Our analysis is theoretical, intended to contribute to a theory of positive political science in which social actors are motivated by the pursuit of power as measured by objective power indices. Our starting points are the papers by Riker (Behavioural Science, 1959,“A test of the adequacy of the power index”) and Coleman (American Sociological Review, 1973,“Loss of Power”).
Abstract: The constitutions of the Bretton Woods Institutions require decisions to be taken by we... more Abstract: The constitutions of the Bretton Woods Institutions require decisions to be taken by weighted voting: each member country possesses a number of votes, depending on its quota allocation, all of which must always be cast as a bloc. This leads to a problem of democratic legitimacy since a member's influence or voting power within such decision-making systems does not necessarily correspond to its voting weight.
Abstract The posterior cingulate cortex (PCC) is a central part of the default mode network (DMN)... more Abstract The posterior cingulate cortex (PCC) is a central part of the default mode network (DMN) and part of the structural core of the brain. Although the PCC often shows consistent deactivation when attention is focused on external events, anatomical studies show that the region is not homogeneous, and electrophysiological recordings in nonhuman primates suggest that it is directly involved in some forms of attention.
Abstract: The development of analogical reasoning has traditionally been understood in terms of t... more Abstract: The development of analogical reasoning has traditionally been understood in terms of theories of adult competence. This approach emphasizes structured representations and structure mapping. In contrast, we argue that by taking a developmental perspective, analogical reasoning can be viewed as the product of a substantially different cognitive ability–relational priming.
Abstract There is considerable uncertainty about the function of the posterior cingulate cortex (... more Abstract There is considerable uncertainty about the function of the posterior cingulate cortex (PCC). The PCC is a major node within the default mode network (DMN) and has high metabolic activity and dense structural connectivity to widespread brain regions, which suggests it has a role as a cortical hub. The region appears to be involved in internally directed thought, for example, memory recollection.
Abstract Traumatic brain injury (TBI) frequently produces impairments of attention in humans. The... more Abstract Traumatic brain injury (TBI) frequently produces impairments of attention in humans. These can result in a failure to maintain consistent goal-directed behavior. A predominantly right-lateralized frontoparietal network is often engaged during attentionally demanding tasks. However, lapses of attention have also been associated with increases in activation within the default mode network (DMN).
Summary White matter disruption is an important determinant of cognitive impairment after brain i... more Summary White matter disruption is an important determinant of cognitive impairment after brain injury, but conventional neuroimaging underestimates its extent. In contrast, diffusion tensor imaging provides a validated and sensitive way of identifying the impact of axonal injury. The relationship between cognitive impairment after traumatic brain injury and white matter damage is likely to be complex.
Abstract Psychedelic drugs have a long history of use in healing ceremonies, but despite renewed ... more Abstract Psychedelic drugs have a long history of use in healing ceremonies, but despite renewed interest in their therapeutic potential, we continue to know very little about how they work in the brain. Here we used psilocybin, a classic psychedelic found in magic mushrooms, and a task-free functional MRI (fMRI) protocol designed to capture the transition from normal waking consciousness to the psychedelic state.
Abstract This study compared the comprehension of syntactically simple with more complex sentence... more Abstract This study compared the comprehension of syntactically simple with more complex sentences in Italian/English adult bilinguals and monolingual controls in the presence or absence of sentence-level interference. The task was to identify the agent of the sentence and we primarily examined the accuracy of response.
Summary Traumatic brain injury often results in cognitive impairments that limit recovery. The un... more Summary Traumatic brain injury often results in cognitive impairments that limit recovery. The underlying pathophysiology of these impairments is uncertain, which restricts clinical assessment and management.
Resumen Las constituciones de las Instituciones de Bretton Woods exigen la toma de decisiones por... more Resumen Las constituciones de las Instituciones de Bretton Woods exigen la toma de decisiones por votación ponderada: cada país miembro posee un número de votos, dependiendo de su asignación de cuota, los cuales deben siempre emitirse en bloque. Esto deriva en un problema de legitimidad democrática dado que la influencia o poder de voto de un miembro dentro de dichos sistemas de toma de decisión no se corresponde necesariamente con la ponderación de votos.
Abstract Auditory and written language in humans' comprehension necessitates attention to the mes... more Abstract Auditory and written language in humans' comprehension necessitates attention to the message of interest and suppression of interference from distracting sources. Investigating the brain areas associated with the control of interference is challenging because it is inevitable that activation of the brain regions that control interference co-occurs with activation related to interference per se.
We present two experiments assessing whether the size of a transformation instantiating a relatio... more We present two experiments assessing whether the size of a transformation instantiating a relation between two states of the world (eg, shrinks) is a performance factor affecting analogical reasoning. The first experiment finds evidence of transformation size as a significant factor in adolescent analogical problem solving while the second experiment finds a similar effect on adult analogical reasoning using a markedly different analogical completion paradigm.
Mirror neurons are single cells found in macaque premotor and parietal cortices that are active d... more Mirror neurons are single cells found in macaque premotor and parietal cortices that are active during action execution and observation. In non-human primates, mirror neurons have only been found in relation to object-directed movements or communicative gestures, as non-object directed actions of the upper limb are not well characterized in non-human primates.
Congenital developmental disorders can result in a wide range of language outcomes. At one extrem... more Congenital developmental disorders can result in a wide range of language outcomes. At one extreme, children with some disorders never master complex language use. At the other extreme, after an initial period of delay, some children may achieve a language outcome indistinguishable from that of typically developing peers.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2011
These can result in a failure to maintain consistent goal-directed behavior. A predominantly righ... more These can result in a failure to maintain consistent goal-directed behavior. A predominantly right-lateralized frontoparietal network is often engaged during attentionally demanding tasks. However, lapses of attention have also been associated with increases in activation within the default mode network (DMN). Here, we study TBI patients with sustained attention impairment, defined on the basis of the consistency of their behavioral performance over time. We show that sustained attention impairments in patients are associated with an increase in DMN activation, particularly within the precuneus and posterior cingulate cortex. Furthermore, the interaction of the precuneus with the rest of the DMN at the start of the task, i.e., its functional connectivity, predicts which patients go on to show impairments of attention. Importantly, this predictive information is present before any behavioral evidence of sustained attention impairment, and the relationship is also found in a subgroup of patients without focal brain damage. TBI often results in diffuse axonal injury, which produces cognitive impairment by disconnecting nodes in distributed brain networks. Using diffusion tensor imaging, we demonstrate that structural disconnection within the DMN also correlates with the level of sustained attention. These results show that abnormalities in DMN function are a sensitive marker of impairments of attention and suggest that changes in connectivity within the DMN are central to the development of attentional impairment after TBI.
Abstract This review considers speaking in a second language from the perspective of motor–sensor... more Abstract This review considers speaking in a second language from the perspective of motor–sensory control. Previous studies relating brain function to the prior acquisition of two or more languages (neurobilingualism) have investigated the differential demands made on linguistic representations and processes, and the role of domain-general cognitive control systems when speakers switch between languages.
Using functional MRI, we investigated whether auditory processing of both speech and meaningful n... more Using functional MRI, we investigated whether auditory processing of both speech and meaningful non-linguistic environmental sounds in superior and middle temporal cortex relies on a complex and spatially distributed neural system. We found that evidence for spatially distributed processing of speech and environmental sounds in a substantial extent of temporal cortices. Most importantly, regions previously reported as selective for speech over environmental sounds also contained distributed information.
Abstract One functional anatomical model of reading, drawing on human neuropsychological and neur... more Abstract One functional anatomical model of reading, drawing on human neuropsychological and neuroimaging data, proposes that a region in left ventral occipitotemporal cortex (vOT) becomes, through experience, specialized for written word perception. We tested this hypothesis by presenting numbers in orthographical and digital form with two task demands, phonological and numerical.
Abstract Regions of the human temporal lobe show greater activation for speech than for other sou... more Abstract Regions of the human temporal lobe show greater activation for speech than for other sounds. These differences may reflect intrinsically specialized domain-specific adaptations for processing speech, or they may be driven by the significant expertise we have in listening to the speech signal. To test the expertise hypothesis, we used a video-game-based paradigm that tacitly trained listeners to categorize acoustically complex, artificial nonlinguistic sounds.
Abstract We investigate the method of power indices to study voting power of members of a legisla... more Abstract We investigate the method of power indices to study voting power of members of a legislature that has voting blocs. Our analysis is theoretical, intended to contribute to a theory of positive political science in which social actors are motivated by the pursuit of power as measured by objective power indices. Our starting points are the papers by Riker (Behavioural Science, 1959,“A test of the adequacy of the power index”) and Coleman (American Sociological Review, 1973,“Loss of Power”).
Abstract: The constitutions of the Bretton Woods Institutions require decisions to be taken by we... more Abstract: The constitutions of the Bretton Woods Institutions require decisions to be taken by weighted voting: each member country possesses a number of votes, depending on its quota allocation, all of which must always be cast as a bloc. This leads to a problem of democratic legitimacy since a member's influence or voting power within such decision-making systems does not necessarily correspond to its voting weight.
Abstract The posterior cingulate cortex (PCC) is a central part of the default mode network (DMN)... more Abstract The posterior cingulate cortex (PCC) is a central part of the default mode network (DMN) and part of the structural core of the brain. Although the PCC often shows consistent deactivation when attention is focused on external events, anatomical studies show that the region is not homogeneous, and electrophysiological recordings in nonhuman primates suggest that it is directly involved in some forms of attention.
Abstract: The development of analogical reasoning has traditionally been understood in terms of t... more Abstract: The development of analogical reasoning has traditionally been understood in terms of theories of adult competence. This approach emphasizes structured representations and structure mapping. In contrast, we argue that by taking a developmental perspective, analogical reasoning can be viewed as the product of a substantially different cognitive ability–relational priming.
Abstract There is considerable uncertainty about the function of the posterior cingulate cortex (... more Abstract There is considerable uncertainty about the function of the posterior cingulate cortex (PCC). The PCC is a major node within the default mode network (DMN) and has high metabolic activity and dense structural connectivity to widespread brain regions, which suggests it has a role as a cortical hub. The region appears to be involved in internally directed thought, for example, memory recollection.
Abstract Traumatic brain injury (TBI) frequently produces impairments of attention in humans. The... more Abstract Traumatic brain injury (TBI) frequently produces impairments of attention in humans. These can result in a failure to maintain consistent goal-directed behavior. A predominantly right-lateralized frontoparietal network is often engaged during attentionally demanding tasks. However, lapses of attention have also been associated with increases in activation within the default mode network (DMN).
Summary White matter disruption is an important determinant of cognitive impairment after brain i... more Summary White matter disruption is an important determinant of cognitive impairment after brain injury, but conventional neuroimaging underestimates its extent. In contrast, diffusion tensor imaging provides a validated and sensitive way of identifying the impact of axonal injury. The relationship between cognitive impairment after traumatic brain injury and white matter damage is likely to be complex.
Abstract Psychedelic drugs have a long history of use in healing ceremonies, but despite renewed ... more Abstract Psychedelic drugs have a long history of use in healing ceremonies, but despite renewed interest in their therapeutic potential, we continue to know very little about how they work in the brain. Here we used psilocybin, a classic psychedelic found in magic mushrooms, and a task-free functional MRI (fMRI) protocol designed to capture the transition from normal waking consciousness to the psychedelic state.
Abstract This study compared the comprehension of syntactically simple with more complex sentence... more Abstract This study compared the comprehension of syntactically simple with more complex sentences in Italian/English adult bilinguals and monolingual controls in the presence or absence of sentence-level interference. The task was to identify the agent of the sentence and we primarily examined the accuracy of response.
Summary Traumatic brain injury often results in cognitive impairments that limit recovery. The un... more Summary Traumatic brain injury often results in cognitive impairments that limit recovery. The underlying pathophysiology of these impairments is uncertain, which restricts clinical assessment and management.
Resumen Las constituciones de las Instituciones de Bretton Woods exigen la toma de decisiones por... more Resumen Las constituciones de las Instituciones de Bretton Woods exigen la toma de decisiones por votación ponderada: cada país miembro posee un número de votos, dependiendo de su asignación de cuota, los cuales deben siempre emitirse en bloque. Esto deriva en un problema de legitimidad democrática dado que la influencia o poder de voto de un miembro dentro de dichos sistemas de toma de decisión no se corresponde necesariamente con la ponderación de votos.
Abstract Auditory and written language in humans' comprehension necessitates attention to the mes... more Abstract Auditory and written language in humans' comprehension necessitates attention to the message of interest and suppression of interference from distracting sources. Investigating the brain areas associated with the control of interference is challenging because it is inevitable that activation of the brain regions that control interference co-occurs with activation related to interference per se.
We present two experiments assessing whether the size of a transformation instantiating a relatio... more We present two experiments assessing whether the size of a transformation instantiating a relation between two states of the world (eg, shrinks) is a performance factor affecting analogical reasoning. The first experiment finds evidence of transformation size as a significant factor in adolescent analogical problem solving while the second experiment finds a similar effect on adult analogical reasoning using a markedly different analogical completion paradigm.
Mirror neurons are single cells found in macaque premotor and parietal cortices that are active d... more Mirror neurons are single cells found in macaque premotor and parietal cortices that are active during action execution and observation. In non-human primates, mirror neurons have only been found in relation to object-directed movements or communicative gestures, as non-object directed actions of the upper limb are not well characterized in non-human primates.
Congenital developmental disorders can result in a wide range of language outcomes. At one extrem... more Congenital developmental disorders can result in a wide range of language outcomes. At one extreme, children with some disorders never master complex language use. At the other extreme, after an initial period of delay, some children may achieve a language outcome indistinguishable from that of typically developing peers.
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Papers by Robert Leech