Douglas Burman - Academia.edu (original) (raw)

Papers by Douglas Burman

Research paper thumbnail of Topography of Hippocampal Connectivity with Sensorimotor Cortex Revealed by Optimizing Smoothing Kernel and Voxel Size

Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation... more Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation studies, typically using a multivoxel seed with specified radius for connectivity analysis. This study identified optimal processing parameters for evaluating hippocampal connectivity with sensorimotor cortex (SMC), comparing effectiveness by varying parameters during both activation and connectivity analysis. Using both 3mm and 4mm isovoxels, smoothing kernels of 6-10mm were evaluated on the amplitude and extent of motor activation and hippocampal connectivity with SMC. Psychophysiological interactions identified hippocampal connectivity with SMC during volitional movements, and connectivity effects from multivoxel seeds were compared with alternate methods; a structural seed represented the mean connectivity map from all voxels within a region, whereas a functional seed represented the regional voxel with maximal SMC connectivity. With few exceptions, the same parameters were optimal for activation and connectivity. Larger isovoxels showed larger activation volumes in both SMC and the hippocampus; connectivity volumes from structural seeds were also larger, except from the posterior hippocampus. Regardless of voxel size, the 10mm smoothing kernel generated larger activation and connectivity volumes from structural seeds, as well as larger beta estimates at connectivity maxima; structural seeds also produced larger connectivity volumes than multivoxel seeds. Functional seeds showed lesser effects from voxel size and smoothing kernels. Optimal parameters revealed topography in structural seed connectivity along both the longitudinal axis and mediolateral axis of the hippocampus. These results indicate larger voxels and smoothing kernels improve sensitivity for detecting both cortical activation and hippocampal connectivity. .

Research paper thumbnail of Normal Alert Consciousness - A Central Executive Model of Hippocampal Function

IntechOpen eBooks, Jul 19, 2023

The relationship between brain and consciousness has been debated since Descartes in the 1500s, n... more The relationship between brain and consciousness has been debated since Descartes in the 1500s, new theories arising in the twentieth century with the development of modern neuroscience. All are controversial due to the lack of consensus on the definition of consciousness, what cognitive properties must be explained, and how to evaluate sentience. Most theoretical explanations bear little relationship to our inner conscious experiences. In the current monograph, the normal alert state of consciousness is defined, and components to be explained are delineated. Debunking misconceptions from previous theories and presenting new evidence, a model is proposed whereby the hippocampus plays a central role in executing and coordinating cognitive functions associated with normal alert consciousness. Key elements of the model reflect recent findings that the combined effect from the left and right hippocampus influences other regions involved in performing many or all cognitive tasks while filtering out irrelevant information. Methods are described for testing the model. Finally, implications are discussed for a variety of neurological disorders and philosophophical issues, including free will and the possibility of sentience in artificial intelligence.

Research paper thumbnail of Introductory Chapter: A Brief Survey of the Functional Roles of the Hippocampus

IntechOpen eBooks, Jul 19, 2023

Research paper thumbnail of Opponent-color responses in macaque extrageniculate visual pathways: the lateral pulvinar

Brain Research, Dec 1, 1983

Single unit recordings made from the lateral pulvinar of macaque monkeys revealed the presence of... more Single unit recordings made from the lateral pulvinar of macaque monkeys revealed the presence of some neurons with color-opponent properties. These findings represent the first report of color-opponent neurons in a subcortical component of the extrageniculate visual pathway.

Research paper thumbnail of Primate frontal eye field activity during natural scanning eye movements

Journal of Neurophysiology, Mar 1, 1994

Research paper thumbnail of Hippocampal connectivity with sensorimotor cortex during volitional finger movements: Laterality and relationship to motor learning

PLOS ONE, Sep 19, 2019

Hippocampal interactions with the motor system are often assumed to reflect the role of memory in... more Hippocampal interactions with the motor system are often assumed to reflect the role of memory in motor learning. Here, we examine hippocampal connectivity with sensorimotor cortex during two tasks requiring paced movements, one with a mnemonic component (sequence learning) and one without (repetitive tapping). Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects; connectivity was identified from sensorimotor cortex correlations with psychophysiological interactions in hippocampal activity between motor and passive visual tasks. Finger movements in both motor tasks anticipated the timing of the metronome, reflecting cognitive control, yet evidence of motor learning was limited to the sequence learning task; nonetheless, hippocampal connectivity was observed during both tasks. Connectivity from corresponding regions in the left and right hippocampus overlapped extensively, with improved sensitivity resulting from their conjunctive (global) analysis. Positive and negative connectivity were both evident, with positive connectivity in sensorimotor cortex ipsilateral to the moving hand during unilateral movements, whereas negative connectivity was prominent in whichever hemisphere was most active during movements. Results implicate the hippocampus in volitional finger movements even in the absence of motor learning or recall.

Research paper thumbnail of Hippocampal connectivity with sensorimotor cortex during volitional finger movements I. Laterality and relationship to motor learning

bioRxiv (Cold Spring Harbor Laboratory), Nov 26, 2018

Hippocampal interactions with the motor system are often assumed to reflect the role of memory in... more Hippocampal interactions with the motor system are often assumed to reflect the role of memory in motor learning. Here, we examine hippocampal connectivity with sensorimotor cortex during two tasks requiring paced movements, one with a mnemonic component (sequence learning) and one without (repetitive tapping). Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects; connectivity was identified from sensorimotor cortex (SMC) correlations with psychophysiological interactions in hippocampal activity between motor and passive visual tasks. Finger movements in both motor tasks anticipated the timing of the metronome, reflecting cognitive control, yet evidence of motor learning was limited to the sequence learning task; nonetheless, hippocampal connectivity was observed during both tasks. Connectivity from corresponding regions in the left and right hippocampus overlapped extensively, with improved sensitivity resulting from their conjunctive (global) analysis. The cortical laterality of SMC connectivity depended both on the hippocampal source and the task. Functionally-defined seeds produced bilateral connectivity within the hand representation, regardless of whether finger movements were uni-or bimanual; these seeds were located midlateral within the hippocampus, whereas structural seeds were located in the posterior hippocampus and produced unilateral connectivity. Results implicate the hippocampus in volitional finger movements even in the absence of motor learning or recall.

Research paper thumbnail of Temporal and spatial selectivity of hippocampal connectivity with sensorimotor cortex during individual finger movements

bioRxiv (Cold Spring Harbor Laboratory), Nov 26, 2018

Cognitive control refers to brain processes involved in regulating behavior according to internal... more Cognitive control refers to brain processes involved in regulating behavior according to internal goals or plans. This study examines whether hippocampal connectivity with sensorimotor cortex during paced movements shows a pattern of spatial and temporal selectivity required for cognitive control. Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects during a paced, non-mnemonic (repetitive tapping) motor task. Connectivity was examined from psychophysiological interactions in hippocampal activity during two analyses: the first identified motor interactions relative to rest, whereas the second identified differential motor activity between adjacent fingers. Connectivity was observed in both pre-and postcentral gyrus, but only postcentral connectivity was topographical, coincident with finger representations identified in a previous study. Differences in the magnitude of connectivity were observed between finger representations, representing spatial selectivity for the target of movements; the postcentral representation of the moving finger invariably showed greater connectivity than adjacent fingers. Furthermore, the magnitude of connectivity within a pre-or postcentral finger representation was largest when its finger moved, representing temporal selectivity for movement. While the hippocampus is known to be sensitive to spatial and temporal features of the environment, consistent with its role in learning and memory, the pattern of spatial and temporal selectivity of hippocampal connectivity observed in this study occurred during volitional movements in the absence of motor learning or recall. Spatial and temporal selectivity of connectivity during volitional movements meets the criteria for cognitive control adapted from oculomotor studies, suggesting a role for the hippocampus in motor control. .

Research paper thumbnail of Topography of hippocampal connectivity with sensorimotor cortex revealed by optimizing smoothing kernel and voxel size

PLOS ONE, Dec 7, 2021

Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation... more Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation studies, typically using a multivoxel seed with specified radius for connectivity analysis. This study identified optimal processing parameters for evaluating hippocampal connectivity with sensorimotor cortex (SMC), comparing effectiveness by varying parameters during both activation and connectivity analysis. Using both 3mm and 4mm isovoxels, smoothing kernels of 0-10mm were evaluated on the amplitude and extent of motor activation and hippocampal connectivity with SMC. Psychophysiological interactions (PPI) identified hippocampal connectivity with SMC during volitional movements, and connectivity effects from multivoxel seeds were compared with alternate methods; a structural seed represented the mean connectivity map from all voxels within a region, whereas a functional seed represented the regional voxel with maximal SMC connectivity. With few exceptions, the same parameters were optimal for activation and connectivity. Larger isovoxels showed larger activation volumes in both SMC and the hippocampus; connectivity volumes from structural seeds were also larger, except from the posterior hippocampus. Regardless of voxel size, the 10mm smoothing kernel generated larger activation and connectivity volumes from structural seeds, as well as larger beta estimates at connectivity maxima; structural seeds also produced larger connectivity volumes than multivoxel seeds. Functional seeds showed lesser effects from voxel size and smoothing kernels. Optimal parameters revealed topography in structural seed connectivity along both the longitudinal axis and mediolateral axis of the hippocampus. These results indicate larger voxels and smoothing kernels can improve sensitivity for detecting both cortical activation and hippocampal connectivity.

Research paper thumbnail of Altered Finger Representations in Sensorimotor Cortex of Musicians with Focal Dystonia: Precentral Cortex

Brain Imaging and Behavior, Oct 8, 2008

Using functional magnetic resonance imaging (fMRI), finger representations were characterized in... more Using functional magnetic resonance imaging
(fMRI), finger representations were characterized in the
precentral cortex of 11 normal musicians and 14 musicians
with focal task-specific dystonia. Finger representations
were identified from differential activation during repetitive
movements of each finger relative to others. Despite group
similarities in topography, abnormalities in representations
of affected fingers were identified. For the finger showing
chronic flexion (primary dystonic finger or PDF), the
cortical “disparity” from its normal location and the
distance to the adjacent finger were increased. By contrast,
representational characteristics of the finger showing
chronic extension (primary compensatory finger or PCF)
did not differ significantly from the control group, but did
differ from those of the PDF. Regardless of whether either
finger's representation differed substantively from normal,
the PCF consistently showed greater volume of activation
than the PDF or other fingers. These findings reflect
dysfunctional interactions between at least two fingers and
their cortical representations.

Research paper thumbnail of Neural correlates of mapping from phonology to orthography in children performing an auditory spelling task

Developmental Science, Jul 1, 2007

Age-related differences (9-to 15-year-olds) in the neural correlates of mapping from phonology to... more Age-related differences (9-to 15-year-olds) in the neural correlates of mapping from phonology to orthography were examined with functional magnetic resonance imaging (fMRI). Participants were asked to determine if two spoken words had the same spelling for the rime (corresponding letters after the first consonant or consonant cluster). Some of the word pairs had conflicting orthography and phonology (e.g. jazz-has, pint-mint) whereas other pairs had non-conflicting information (e.g. press-list, gate-hate) (see Table 1). There were age-related increases in activation for lexical processing (across conflicting and non-conflicting conditions) in left inferior parietal lobule, suggesting that older children have a more elaborated system for mapping between phonology and orthography that includes connections at different grain sizes (e.g. phonemes, onset-rimes, syllables). In addition, we found that the conflicting conditions had lower accuracy, slower reaction time and greater activation in left inferior frontal gyrus as compared to non-conflicting conditions. Higher accuracy was also correlated with greater activation in left inferior frontal gyrus for the most difficult conflicting condition (e.g. jazz-has). The finding of both a conflict effect and a correlation with accuracy in left inferior frontal gyrus suggests that this region may be involved in resolving the conflict between orthographic and phonological representations.

Research paper thumbnail of A neuroimaging dataset on response inhibition and selective attention in adults and children with and without ADHD

Data in Brief, Aug 1, 2021

In this article we describe the dataset titled “Response inhibition and selective attention in ad... more In this article we describe the dataset titled “Response inhibition and selective attention in adults and children with and without ADHD” which is publicly available on OpenNeuro.org. This dataset is comprised of neuroimaging and standardized cognitive assessment scores from 11 adults, 12 children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) and 15 age matched children without ADHD. Functional Magnetic Resonance Imaging (fMRI) data were collected while participants completed selective attention and response inhibition tasks designed and balanced for within or cross-task comparisons. Previous research utilizing this dataset has yet to explore associations between brain function and cognitive assessment scores or differences in neural processes across stimuli features making this dataset valuable for its future contributions to the field as well as replication of prior findings.

Research paper thumbnail of Developmental differences in brain systems for reading

Functional magnetic resonance imaging (fMRl) was used to examine the distribution of brain activa... more Functional magnetic resonance imaging (fMRl) was used to examine the distribution of brain activation during four visual word-processing tasks performed by children (9-12 years) and adults (21-31 years). The four tasks were designed to separately emphasize orthographic, phonological, semantic, and syntactic processes. As expected, the adults performed these tasks more efficiently than the children, who were significantly less accurate in their performance. The patterns of brain activation in the two groups suggest that efficient processing of visual word forms in adults results in part from three trends. (1) A shift in activation from multimodal areas (namely, Wernicke's area in children) to activation of unimodal association areas (fusiform cortex in adults). (2) More restricted interactions between cortical areas in adults as the areas involved in linguistic processes become more specialized and efficient. (3) Overlap of areas associated with high accuracy and quick reaction times in adults as word representations become more directly accessible to areas involved in preparing a behavioral response. These trends reflect plasticity in neural processing during maturation, a process that effectively frees resources for processing unfamiliar stimuli as the ability to respond quickly and accurately to familiar stimuli improves.

Research paper thumbnail of Development of Lexical and Sentence Level Context Effects for Dominant and Subordinate Word Meanings of Homonyms

Journal of Psycholinguistic Research, Oct 12, 2006

Nine-ten-and twelve-year-old children (N = 75) read aloud dominant, subordinate or ambiguous bias... more Nine-ten-and twelve-year-old children (N = 75) read aloud dominant, subordinate or ambiguous bias sentences (N = 120) that ended in a homonym (BALL). After the sentence (1,000 ms), children read aloud targets that were related to the dominant (BAT) or subordinate (DANCE) meaning of the homonym or control targets. Participants were also divided into three reading skill groups based on an independent measure of single word oral reading accuracy. There were three main developmental and reading skill findings. First, 9-year-olds and low skill readers showed lexical level facilitation in accuracy. Second, 9-and 10-year-olds or low and moderate skill readers showed lexical level facilitation in reaction time. Third, 12-year-olds or high skill readers showed sentence level facilitation in reaction time with high skill readers additionally showing sentence level inhibition in reaction time. These results show that lexical level context effects decreased and that sentence level context effects increased with development and skill. These results are discussed in terms of connectionist models of visual word recognition that incorporate distributed attractor principles.

Research paper thumbnail of Developmental increases in effective connectivity to brain regions involved in phonological processing during tasks with orthographic demands

Brain Research, 2008

Developmental differences (9-to 15-year-olds) in effective connectivity in left hemisphere region... more Developmental differences (9-to 15-year-olds) in effective connectivity in left hemisphere regions were examined using dynamic causal modeling (DCM) of functional magnetic resonance imaging (fMRI) data. Children completed spelling tasks in the visual and auditory modalities in which they were asked to determine if two words were spelled the same from the first vowel onwards. Intrinsic (anatomical) connections were strongest from primary cortical regions to unimodal association areas-from Heschl's gyrus to superior temporal gyrus for the auditory spelling task and from calcarine to fusiform gyrus for the visual spelling task. The modulatory (experimental) effect for the visual spelling task from calcarine to superior temporal gyrus was stronger than all other effects from calcarine and this effect showed a developmental increase, suggesting automatic activation of phonology that increased with age. The modulatory effect from Heschl's gyrus to dorsal inferior frontal gyrus also showed a developmental increase, suggesting age-related increases in phonological segmentation in verbal working memory. All together, these results suggest that there are developmental increases in automatic access into brain regions involved in phonological processing in tasks that require orthographic processing.

Research paper thumbnail of Developmental Increase in Top–Down and Bottom–Up Processing in a Phonological Task: An Effective Connectivity, fMRI Study

Journal of Cognitive Neuroscience, Jun 1, 2009

We examined age-related changes in the interactions among brain regions in children performing rh... more We examined age-related changes in the interactions among brain regions in children performing rhyming judgments on visually presented words. The difficulty of the task was manipulated by including a conflict between task-relevant (phonological) information and task-irrelevant (orthographic) information. The conflicting conditions included pairs of words that rhyme despite having different spelling patterns (jazz-has), or words that do not rhyme despite having similar spelling patterns (pint-mint). These were contrasted with nonconflicting pairs that have similar orthography and phonology (dime-lime) or different orthography and phonology (press-list). Using fMRI, we examined effective connectivity among five left hemisphere regions of interest: fusiform gyrus (FG), inferior frontal gyrus (IFG), intraparietal sulcus (IPS), lateral temporal cortex (LTC), and medial frontal gyrus (MeFG). Age-related increases were observed in the influence of the IFG and FG on the LTC, but only in conflicting conditions. These results reflect a developmental increase in the convergence of bottom-up and top-down information on the LTC. In older children, top-down control process may selectively enhance the sensitivity of the LTC to bottom-up information from the FG. This may be evident especially in situations that require selective enhancement of taskrelevant versus task-irrelevant information. Altogether these results provide a direct evidence for a developmental increase in top-down control processes in language processing. The developmental increase in bottom-up processing may be secondary to the enhancement of top-down processes.

Research paper thumbnail of Development and Disorders of Neurocognitive Systems for Oral Language and Reading

Learning Disability Quarterly, Aug 1, 2001

There are four goals of this article. First, a tentative neurocognitive model of oral language an... more There are four goals of this article. First, a tentative neurocognitive model of oral language and reading is outlined. Second, our recent functional magnetic resonance imaging studies (fMRI) on the development of oral language and reading are briefly reviewed with reference to this neurocognitive model. Third, brain-imaging research on dyslexia is discussed in light of the neurocognitive model. Fourth, research on the plasticity of neural systems and the implication of this plasticity for studying normative development and disorders is presented.

Research paper thumbnail of Differential prefrontal–temporal neural correlates of semantic processing in children

Brain and Language, Dec 1, 2006

This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlatio... more This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlations in a group of 16 children (9-to 12-year-olds). Activation was measured during a semantic judgment task presented in either the visual or auditory modality that required the individual to determine whether a final word was related in meaning to one of two previous words (e.g., foundtank-lost). The main finding was that higher performers (i.e., accuracy) were associated with more activation in posterior representational systems including the inferior and middle temporal gyri, whereas lower performers were associated with more activation in anterior regions including the inferior and middle frontal gyri. This pattern of results was interpreted as reflecting an elaborated semantic representational system in temporal areas for the high accuracy performers that allowed them to efficiently and accurately make meaning based judgments. The low accuracy performers may have an inaccurate or weakly interconnected semantic system that results in greater use of frontal areas in a feature selection process.

Research paper thumbnail of The Development of Automatic Brain Systems in Reading and Oral Language

Research paper thumbnail of Children with reading disorder show modality independent brain abnormalities during semantic tasks

Neuropsychologia, 2007

Neuroimaging studies have suggested that left inferior frontal gyrus, left inferior parietal lobu... more Neuroimaging studies have suggested that left inferior frontal gyrus, left inferior parietal lobule and left middle temporal gyrus are critical for semantic processing in normal children. The goal of the present functional magnetic resonance imaging (fMRI) study was to determine whether these regions are systematically related to semantic processing in children (9-to 15-year-old) diagnosed with reading disorders (RD). Semantic judgments required participants to indicate whether two words were related in meaning. The strength of semantic association varied continuously from higher association pairs (e.g., king-queen) to lower association pairs (e.g. net-ship). We found that the correlation between association strength and activation was significantly weaker for RD children compared to controls in left middle temporal gyrus and left inferior parietal lobule for both the auditory and the visual modalities and in left inferior frontal gyrus for the visual modality. These results suggest that the RD children have abnormalities in semantic search/retrieval in the inferior frontal gyrus, integration of semantic information in the inferior parietal lobule and semantic lexical representations in the middle temporal gyrus. These deficits appear to be general to the semantic system and independent of modality.

Research paper thumbnail of Topography of Hippocampal Connectivity with Sensorimotor Cortex Revealed by Optimizing Smoothing Kernel and Voxel Size

Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation... more Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation studies, typically using a multivoxel seed with specified radius for connectivity analysis. This study identified optimal processing parameters for evaluating hippocampal connectivity with sensorimotor cortex (SMC), comparing effectiveness by varying parameters during both activation and connectivity analysis. Using both 3mm and 4mm isovoxels, smoothing kernels of 6-10mm were evaluated on the amplitude and extent of motor activation and hippocampal connectivity with SMC. Psychophysiological interactions identified hippocampal connectivity with SMC during volitional movements, and connectivity effects from multivoxel seeds were compared with alternate methods; a structural seed represented the mean connectivity map from all voxels within a region, whereas a functional seed represented the regional voxel with maximal SMC connectivity. With few exceptions, the same parameters were optimal for activation and connectivity. Larger isovoxels showed larger activation volumes in both SMC and the hippocampus; connectivity volumes from structural seeds were also larger, except from the posterior hippocampus. Regardless of voxel size, the 10mm smoothing kernel generated larger activation and connectivity volumes from structural seeds, as well as larger beta estimates at connectivity maxima; structural seeds also produced larger connectivity volumes than multivoxel seeds. Functional seeds showed lesser effects from voxel size and smoothing kernels. Optimal parameters revealed topography in structural seed connectivity along both the longitudinal axis and mediolateral axis of the hippocampus. These results indicate larger voxels and smoothing kernels improve sensitivity for detecting both cortical activation and hippocampal connectivity. .

Research paper thumbnail of Normal Alert Consciousness - A Central Executive Model of Hippocampal Function

IntechOpen eBooks, Jul 19, 2023

The relationship between brain and consciousness has been debated since Descartes in the 1500s, n... more The relationship between brain and consciousness has been debated since Descartes in the 1500s, new theories arising in the twentieth century with the development of modern neuroscience. All are controversial due to the lack of consensus on the definition of consciousness, what cognitive properties must be explained, and how to evaluate sentience. Most theoretical explanations bear little relationship to our inner conscious experiences. In the current monograph, the normal alert state of consciousness is defined, and components to be explained are delineated. Debunking misconceptions from previous theories and presenting new evidence, a model is proposed whereby the hippocampus plays a central role in executing and coordinating cognitive functions associated with normal alert consciousness. Key elements of the model reflect recent findings that the combined effect from the left and right hippocampus influences other regions involved in performing many or all cognitive tasks while filtering out irrelevant information. Methods are described for testing the model. Finally, implications are discussed for a variety of neurological disorders and philosophophical issues, including free will and the possibility of sentience in artificial intelligence.

Research paper thumbnail of Introductory Chapter: A Brief Survey of the Functional Roles of the Hippocampus

IntechOpen eBooks, Jul 19, 2023

Research paper thumbnail of Opponent-color responses in macaque extrageniculate visual pathways: the lateral pulvinar

Brain Research, Dec 1, 1983

Single unit recordings made from the lateral pulvinar of macaque monkeys revealed the presence of... more Single unit recordings made from the lateral pulvinar of macaque monkeys revealed the presence of some neurons with color-opponent properties. These findings represent the first report of color-opponent neurons in a subcortical component of the extrageniculate visual pathway.

Research paper thumbnail of Primate frontal eye field activity during natural scanning eye movements

Journal of Neurophysiology, Mar 1, 1994

Research paper thumbnail of Hippocampal connectivity with sensorimotor cortex during volitional finger movements: Laterality and relationship to motor learning

PLOS ONE, Sep 19, 2019

Hippocampal interactions with the motor system are often assumed to reflect the role of memory in... more Hippocampal interactions with the motor system are often assumed to reflect the role of memory in motor learning. Here, we examine hippocampal connectivity with sensorimotor cortex during two tasks requiring paced movements, one with a mnemonic component (sequence learning) and one without (repetitive tapping). Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects; connectivity was identified from sensorimotor cortex correlations with psychophysiological interactions in hippocampal activity between motor and passive visual tasks. Finger movements in both motor tasks anticipated the timing of the metronome, reflecting cognitive control, yet evidence of motor learning was limited to the sequence learning task; nonetheless, hippocampal connectivity was observed during both tasks. Connectivity from corresponding regions in the left and right hippocampus overlapped extensively, with improved sensitivity resulting from their conjunctive (global) analysis. Positive and negative connectivity were both evident, with positive connectivity in sensorimotor cortex ipsilateral to the moving hand during unilateral movements, whereas negative connectivity was prominent in whichever hemisphere was most active during movements. Results implicate the hippocampus in volitional finger movements even in the absence of motor learning or recall.

Research paper thumbnail of Hippocampal connectivity with sensorimotor cortex during volitional finger movements I. Laterality and relationship to motor learning

bioRxiv (Cold Spring Harbor Laboratory), Nov 26, 2018

Hippocampal interactions with the motor system are often assumed to reflect the role of memory in... more Hippocampal interactions with the motor system are often assumed to reflect the role of memory in motor learning. Here, we examine hippocampal connectivity with sensorimotor cortex during two tasks requiring paced movements, one with a mnemonic component (sequence learning) and one without (repetitive tapping). Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects; connectivity was identified from sensorimotor cortex (SMC) correlations with psychophysiological interactions in hippocampal activity between motor and passive visual tasks. Finger movements in both motor tasks anticipated the timing of the metronome, reflecting cognitive control, yet evidence of motor learning was limited to the sequence learning task; nonetheless, hippocampal connectivity was observed during both tasks. Connectivity from corresponding regions in the left and right hippocampus overlapped extensively, with improved sensitivity resulting from their conjunctive (global) analysis. The cortical laterality of SMC connectivity depended both on the hippocampal source and the task. Functionally-defined seeds produced bilateral connectivity within the hand representation, regardless of whether finger movements were uni-or bimanual; these seeds were located midlateral within the hippocampus, whereas structural seeds were located in the posterior hippocampus and produced unilateral connectivity. Results implicate the hippocampus in volitional finger movements even in the absence of motor learning or recall.

Research paper thumbnail of Temporal and spatial selectivity of hippocampal connectivity with sensorimotor cortex during individual finger movements

bioRxiv (Cold Spring Harbor Laboratory), Nov 26, 2018

Cognitive control refers to brain processes involved in regulating behavior according to internal... more Cognitive control refers to brain processes involved in regulating behavior according to internal goals or plans. This study examines whether hippocampal connectivity with sensorimotor cortex during paced movements shows a pattern of spatial and temporal selectivity required for cognitive control. Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects during a paced, non-mnemonic (repetitive tapping) motor task. Connectivity was examined from psychophysiological interactions in hippocampal activity during two analyses: the first identified motor interactions relative to rest, whereas the second identified differential motor activity between adjacent fingers. Connectivity was observed in both pre-and postcentral gyrus, but only postcentral connectivity was topographical, coincident with finger representations identified in a previous study. Differences in the magnitude of connectivity were observed between finger representations, representing spatial selectivity for the target of movements; the postcentral representation of the moving finger invariably showed greater connectivity than adjacent fingers. Furthermore, the magnitude of connectivity within a pre-or postcentral finger representation was largest when its finger moved, representing temporal selectivity for movement. While the hippocampus is known to be sensitive to spatial and temporal features of the environment, consistent with its role in learning and memory, the pattern of spatial and temporal selectivity of hippocampal connectivity observed in this study occurred during volitional movements in the absence of motor learning or recall. Spatial and temporal selectivity of connectivity during volitional movements meets the criteria for cognitive control adapted from oculomotor studies, suggesting a role for the hippocampus in motor control. .

Research paper thumbnail of Topography of hippocampal connectivity with sensorimotor cortex revealed by optimizing smoothing kernel and voxel size

PLOS ONE, Dec 7, 2021

Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation... more Studies of the hippocampus use smaller voxel sizes and smoothing kernels than cortical activation studies, typically using a multivoxel seed with specified radius for connectivity analysis. This study identified optimal processing parameters for evaluating hippocampal connectivity with sensorimotor cortex (SMC), comparing effectiveness by varying parameters during both activation and connectivity analysis. Using both 3mm and 4mm isovoxels, smoothing kernels of 0-10mm were evaluated on the amplitude and extent of motor activation and hippocampal connectivity with SMC. Psychophysiological interactions (PPI) identified hippocampal connectivity with SMC during volitional movements, and connectivity effects from multivoxel seeds were compared with alternate methods; a structural seed represented the mean connectivity map from all voxels within a region, whereas a functional seed represented the regional voxel with maximal SMC connectivity. With few exceptions, the same parameters were optimal for activation and connectivity. Larger isovoxels showed larger activation volumes in both SMC and the hippocampus; connectivity volumes from structural seeds were also larger, except from the posterior hippocampus. Regardless of voxel size, the 10mm smoothing kernel generated larger activation and connectivity volumes from structural seeds, as well as larger beta estimates at connectivity maxima; structural seeds also produced larger connectivity volumes than multivoxel seeds. Functional seeds showed lesser effects from voxel size and smoothing kernels. Optimal parameters revealed topography in structural seed connectivity along both the longitudinal axis and mediolateral axis of the hippocampus. These results indicate larger voxels and smoothing kernels can improve sensitivity for detecting both cortical activation and hippocampal connectivity.

Research paper thumbnail of Altered Finger Representations in Sensorimotor Cortex of Musicians with Focal Dystonia: Precentral Cortex

Brain Imaging and Behavior, Oct 8, 2008

Using functional magnetic resonance imaging (fMRI), finger representations were characterized in... more Using functional magnetic resonance imaging
(fMRI), finger representations were characterized in the
precentral cortex of 11 normal musicians and 14 musicians
with focal task-specific dystonia. Finger representations
were identified from differential activation during repetitive
movements of each finger relative to others. Despite group
similarities in topography, abnormalities in representations
of affected fingers were identified. For the finger showing
chronic flexion (primary dystonic finger or PDF), the
cortical “disparity” from its normal location and the
distance to the adjacent finger were increased. By contrast,
representational characteristics of the finger showing
chronic extension (primary compensatory finger or PCF)
did not differ significantly from the control group, but did
differ from those of the PDF. Regardless of whether either
finger's representation differed substantively from normal,
the PCF consistently showed greater volume of activation
than the PDF or other fingers. These findings reflect
dysfunctional interactions between at least two fingers and
their cortical representations.

Research paper thumbnail of Neural correlates of mapping from phonology to orthography in children performing an auditory spelling task

Developmental Science, Jul 1, 2007

Age-related differences (9-to 15-year-olds) in the neural correlates of mapping from phonology to... more Age-related differences (9-to 15-year-olds) in the neural correlates of mapping from phonology to orthography were examined with functional magnetic resonance imaging (fMRI). Participants were asked to determine if two spoken words had the same spelling for the rime (corresponding letters after the first consonant or consonant cluster). Some of the word pairs had conflicting orthography and phonology (e.g. jazz-has, pint-mint) whereas other pairs had non-conflicting information (e.g. press-list, gate-hate) (see Table 1). There were age-related increases in activation for lexical processing (across conflicting and non-conflicting conditions) in left inferior parietal lobule, suggesting that older children have a more elaborated system for mapping between phonology and orthography that includes connections at different grain sizes (e.g. phonemes, onset-rimes, syllables). In addition, we found that the conflicting conditions had lower accuracy, slower reaction time and greater activation in left inferior frontal gyrus as compared to non-conflicting conditions. Higher accuracy was also correlated with greater activation in left inferior frontal gyrus for the most difficult conflicting condition (e.g. jazz-has). The finding of both a conflict effect and a correlation with accuracy in left inferior frontal gyrus suggests that this region may be involved in resolving the conflict between orthographic and phonological representations.

Research paper thumbnail of A neuroimaging dataset on response inhibition and selective attention in adults and children with and without ADHD

Data in Brief, Aug 1, 2021

In this article we describe the dataset titled “Response inhibition and selective attention in ad... more In this article we describe the dataset titled “Response inhibition and selective attention in adults and children with and without ADHD” which is publicly available on OpenNeuro.org. This dataset is comprised of neuroimaging and standardized cognitive assessment scores from 11 adults, 12 children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) and 15 age matched children without ADHD. Functional Magnetic Resonance Imaging (fMRI) data were collected while participants completed selective attention and response inhibition tasks designed and balanced for within or cross-task comparisons. Previous research utilizing this dataset has yet to explore associations between brain function and cognitive assessment scores or differences in neural processes across stimuli features making this dataset valuable for its future contributions to the field as well as replication of prior findings.

Research paper thumbnail of Developmental differences in brain systems for reading

Functional magnetic resonance imaging (fMRl) was used to examine the distribution of brain activa... more Functional magnetic resonance imaging (fMRl) was used to examine the distribution of brain activation during four visual word-processing tasks performed by children (9-12 years) and adults (21-31 years). The four tasks were designed to separately emphasize orthographic, phonological, semantic, and syntactic processes. As expected, the adults performed these tasks more efficiently than the children, who were significantly less accurate in their performance. The patterns of brain activation in the two groups suggest that efficient processing of visual word forms in adults results in part from three trends. (1) A shift in activation from multimodal areas (namely, Wernicke's area in children) to activation of unimodal association areas (fusiform cortex in adults). (2) More restricted interactions between cortical areas in adults as the areas involved in linguistic processes become more specialized and efficient. (3) Overlap of areas associated with high accuracy and quick reaction times in adults as word representations become more directly accessible to areas involved in preparing a behavioral response. These trends reflect plasticity in neural processing during maturation, a process that effectively frees resources for processing unfamiliar stimuli as the ability to respond quickly and accurately to familiar stimuli improves.

Research paper thumbnail of Development of Lexical and Sentence Level Context Effects for Dominant and Subordinate Word Meanings of Homonyms

Journal of Psycholinguistic Research, Oct 12, 2006

Nine-ten-and twelve-year-old children (N = 75) read aloud dominant, subordinate or ambiguous bias... more Nine-ten-and twelve-year-old children (N = 75) read aloud dominant, subordinate or ambiguous bias sentences (N = 120) that ended in a homonym (BALL). After the sentence (1,000 ms), children read aloud targets that were related to the dominant (BAT) or subordinate (DANCE) meaning of the homonym or control targets. Participants were also divided into three reading skill groups based on an independent measure of single word oral reading accuracy. There were three main developmental and reading skill findings. First, 9-year-olds and low skill readers showed lexical level facilitation in accuracy. Second, 9-and 10-year-olds or low and moderate skill readers showed lexical level facilitation in reaction time. Third, 12-year-olds or high skill readers showed sentence level facilitation in reaction time with high skill readers additionally showing sentence level inhibition in reaction time. These results show that lexical level context effects decreased and that sentence level context effects increased with development and skill. These results are discussed in terms of connectionist models of visual word recognition that incorporate distributed attractor principles.

Research paper thumbnail of Developmental increases in effective connectivity to brain regions involved in phonological processing during tasks with orthographic demands

Brain Research, 2008

Developmental differences (9-to 15-year-olds) in effective connectivity in left hemisphere region... more Developmental differences (9-to 15-year-olds) in effective connectivity in left hemisphere regions were examined using dynamic causal modeling (DCM) of functional magnetic resonance imaging (fMRI) data. Children completed spelling tasks in the visual and auditory modalities in which they were asked to determine if two words were spelled the same from the first vowel onwards. Intrinsic (anatomical) connections were strongest from primary cortical regions to unimodal association areas-from Heschl's gyrus to superior temporal gyrus for the auditory spelling task and from calcarine to fusiform gyrus for the visual spelling task. The modulatory (experimental) effect for the visual spelling task from calcarine to superior temporal gyrus was stronger than all other effects from calcarine and this effect showed a developmental increase, suggesting automatic activation of phonology that increased with age. The modulatory effect from Heschl's gyrus to dorsal inferior frontal gyrus also showed a developmental increase, suggesting age-related increases in phonological segmentation in verbal working memory. All together, these results suggest that there are developmental increases in automatic access into brain regions involved in phonological processing in tasks that require orthographic processing.

Research paper thumbnail of Developmental Increase in Top–Down and Bottom–Up Processing in a Phonological Task: An Effective Connectivity, fMRI Study

Journal of Cognitive Neuroscience, Jun 1, 2009

We examined age-related changes in the interactions among brain regions in children performing rh... more We examined age-related changes in the interactions among brain regions in children performing rhyming judgments on visually presented words. The difficulty of the task was manipulated by including a conflict between task-relevant (phonological) information and task-irrelevant (orthographic) information. The conflicting conditions included pairs of words that rhyme despite having different spelling patterns (jazz-has), or words that do not rhyme despite having similar spelling patterns (pint-mint). These were contrasted with nonconflicting pairs that have similar orthography and phonology (dime-lime) or different orthography and phonology (press-list). Using fMRI, we examined effective connectivity among five left hemisphere regions of interest: fusiform gyrus (FG), inferior frontal gyrus (IFG), intraparietal sulcus (IPS), lateral temporal cortex (LTC), and medial frontal gyrus (MeFG). Age-related increases were observed in the influence of the IFG and FG on the LTC, but only in conflicting conditions. These results reflect a developmental increase in the convergence of bottom-up and top-down information on the LTC. In older children, top-down control process may selectively enhance the sensitivity of the LTC to bottom-up information from the FG. This may be evident especially in situations that require selective enhancement of taskrelevant versus task-irrelevant information. Altogether these results provide a direct evidence for a developmental increase in top-down control processes in language processing. The developmental increase in bottom-up processing may be secondary to the enhancement of top-down processes.

Research paper thumbnail of Development and Disorders of Neurocognitive Systems for Oral Language and Reading

Learning Disability Quarterly, Aug 1, 2001

There are four goals of this article. First, a tentative neurocognitive model of oral language an... more There are four goals of this article. First, a tentative neurocognitive model of oral language and reading is outlined. Second, our recent functional magnetic resonance imaging studies (fMRI) on the development of oral language and reading are briefly reviewed with reference to this neurocognitive model. Third, brain-imaging research on dyslexia is discussed in light of the neurocognitive model. Fourth, research on the plasticity of neural systems and the implication of this plasticity for studying normative development and disorders is presented.

Research paper thumbnail of Differential prefrontal–temporal neural correlates of semantic processing in children

Brain and Language, Dec 1, 2006

This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlatio... more This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlations in a group of 16 children (9-to 12-year-olds). Activation was measured during a semantic judgment task presented in either the visual or auditory modality that required the individual to determine whether a final word was related in meaning to one of two previous words (e.g., foundtank-lost). The main finding was that higher performers (i.e., accuracy) were associated with more activation in posterior representational systems including the inferior and middle temporal gyri, whereas lower performers were associated with more activation in anterior regions including the inferior and middle frontal gyri. This pattern of results was interpreted as reflecting an elaborated semantic representational system in temporal areas for the high accuracy performers that allowed them to efficiently and accurately make meaning based judgments. The low accuracy performers may have an inaccurate or weakly interconnected semantic system that results in greater use of frontal areas in a feature selection process.

Research paper thumbnail of The Development of Automatic Brain Systems in Reading and Oral Language

Research paper thumbnail of Children with reading disorder show modality independent brain abnormalities during semantic tasks

Neuropsychologia, 2007

Neuroimaging studies have suggested that left inferior frontal gyrus, left inferior parietal lobu... more Neuroimaging studies have suggested that left inferior frontal gyrus, left inferior parietal lobule and left middle temporal gyrus are critical for semantic processing in normal children. The goal of the present functional magnetic resonance imaging (fMRI) study was to determine whether these regions are systematically related to semantic processing in children (9-to 15-year-old) diagnosed with reading disorders (RD). Semantic judgments required participants to indicate whether two words were related in meaning. The strength of semantic association varied continuously from higher association pairs (e.g., king-queen) to lower association pairs (e.g. net-ship). We found that the correlation between association strength and activation was significantly weaker for RD children compared to controls in left middle temporal gyrus and left inferior parietal lobule for both the auditory and the visual modalities and in left inferior frontal gyrus for the visual modality. These results suggest that the RD children have abnormalities in semantic search/retrieval in the inferior frontal gyrus, integration of semantic information in the inferior parietal lobule and semantic lexical representations in the middle temporal gyrus. These deficits appear to be general to the semantic system and independent of modality.