Biomedical subjects

J R Binder

Publications and source records attributed to J R Binder.

17 recordsLinked to original sources

PubMed1997

Distributed neural systems underlying the timing of movements.

Timing is essential to the execution of skilled movements, yet our knowledge of the neural systems underlying timekeeping operations is limited. Using whole-brain functional magnetic resonance imaging, subjects were imaged while tapping with their right index finger in synchrony with tones that were separated by constant intervals [Synchronization (S)], followed by tapping without the benefit of an auditory cue [Continuation (C)]. Two control conditions followed in which subjects listened to tones and then made pitch discriminations (D). Both the S and the C conditions produced equivalent activation within the left sensorimotor cortex, the right cerebellum (dorsal dentate nucleus), and the right superior temporal gyrus (STG). Only the C condition produced activation of a medial premotor system, including the caudal supplementary motor area (SMA), the left putamen, and the left ventrolateral thalamus. The C condition also activated a region within the right inferior frontal gyrus (IFG), which is functionally interconnected with auditory cortex. Both control conditions produced bilateral activation of the STG, and the D condition also activated the rostral SMA. These results suggest that the internal generation of precisely timed movements is dependent on three interrelated neural systems, one that is involved in explicit timing (putamen, ventrolateral thalamus, SMA), one that mediates auditory sensory memory (IFG, STG), and another that is involved in sensorimotor processing (dorsal dentate nucleus, sensorimotor cortex).

Adolescent↗

PubMed1997

Functional MRI evidence for subcortical participation in conceptual reasoning skills.

Lesions involving the dorsolateral prefrontal lobes may produce deficits on conceptual reasoning (CR) tasks in humans. Such deficits can also occur with subcortical lesions involving the basal ganglia, thalamus, or cerebellum, suggesting a common, yet widespread, neural network supporting this executive function. Here we report the results of a whole brain functional magnetic resonance imaging (fMRI) experiment in healthy volunteers while performing a CR task. Compared to a sensorimotor control condition, the CR task resulted in discrete subcortical activation sites primarily involving the right basal ganglia, right thalamus and left lateral cerebellum. Cortical activation was present in multiple systems, including the dorsolateral prefrontal and inferior frontal/insular areas; posterior parietal, superior extrastriate, and premotor areas; inferior extrastriate and middle temporal regions; and midline pre-supplementary motor and anterior cingulate regions. Our findings provide strong evidence that CR is mediated by interacting neural systems involving the cerebral cortex, basal ganglia, thalamus, and cerebellum.

Adult↗

PubMed1997

Human brain language areas identified by functional magnetic resonance imaging.

Functional magnetic resonance imaging (FMRI) was used to identify candidate language processing areas in the intact human brain. Language was defined broadly to include both phonological and lexical-semantic functions and to exclude sensory, motor, and general executive functions. The language activation task required phonetic and semantic analysis of aurally presented words and was compared with a control task involving perceptual analysis of nonlinguistic sounds. Functional maps of the entire brain were obtained from 30 right-handed subjects. These maps were averaged in standard stereotaxic space to produce a robust "average activation map" that proved reliable in a split-half analysis. As predicted from classical models of language organization based on lesion data, cortical activation associated with language processing was strongly lateralized to the left cerebral hemisphere and involved a network of regions in the frontal, temporal, and parietal lobes. Less consistent with classical models were (1) the existence of left hemisphere temporoparietal language areas outside the traditional "Wernicke area," namely, in the middle temporal, inferior temporal, fusiform, and angular gyri; (2) extensive left prefrontal language areas outside the classical "Broca area"; and (3) clear participation of these left frontal areas in a task emphasizing "receptive" language functions. Although partly in conflict with the classical model of language localization, these findings are generally compatible with reported lesion data and provide additional support for ongoing efforts to refine and extend the classical model.

Adolescent↗

PubMed1997

Neuroanatomy of language processing studied with functional MRI.

This article discusses recent data from functional magnetic resonance imaging (FMRI) studies of language. Although preliminary, these data suggest activation of the left prefrontal cortex across a variety of tasks, with less activation of posterior cortical areas known to play a role in language. Potential sources of error in functional imaging studies related to task subtraction techniques are briefly discussed. The semantic decision task used by the author and colleagues, which produces left lateralized activation of both prefrontal and temporoparietal areas, is presented in detail, and the activation pattern observed in these studies is discussed in the context of converging neuropsychological and positron emission tomography data. It is argued that superior temporal responses evoked by listening to speech represent sensory rather than language processes. The data bring into question the classical disconnection model of transcortical aphasia and confirm the participation of left prefrontal areas in comprehension. FMRI shows promise as an alternative to the intracarotid amobarbital test for language dominance.

Brain↗

PubMed1996

Function of the left planum temporale in auditory and linguistic processing.

Previous research suggests that the human left planum temporale (PT) plays an important role in language. To test this hypothesis, functional MRI (fMRI) data were collected from 12 normal right-handed subjects during passive and active listening to words and tone sequences. Several left hemisphere areas, including the superior temporal sulcus, middle temporal gyrus, angular gyrus and lateral frontal lobe showed stronger activation during the word conditions. This was not true of the PT, which responded equally to tones and words during passive listening and more strongly to tones during active listening. The PT is likely to be involved in early auditory processing, while specifically linguistic functions are mediated by multimodal association areas distributed elsewhere in the left hemisphere.

Adult↗

PubMed1996

Relationship between finger movement rate and functional magnetic resonance signal change in human primary motor cortex.

Functional magnetic resonance imaging (FMRI) is a noninvasive technique for mapping regional brain changes in response to sensory, motor, or cognitive activation tasks. Interpretation of these activation experiments may be confounded by more elementary task parameters, such as stimulus presentation or movement rates. We examined the effect of movement rate on the FMRI response recorded from the contralateral primary motor cortex. Four right-handed healthy subjects performed flexion-extension movements of digits 2-5 of the right hand at rates of 1, 2, 3, 4, or 5 Hz. Results of this study indicated a positive linear relationship between movement rate and FMRI signal change. Additionally, the number of voxels demonstrating functional activity increased significantly with faster movement rates. The magnitude of the signal change at each movement rate remained constant over the course of three 8-min scanning series. These findings are similar to those of previous rate studies of the visual and auditory system performed with positron emission tomography (PET) and FMRI.

Adult↗

PubMed1996

Determination of language dominance using functional MRI: a comparison with the Wada test.

We performed functional MRI (FMRI) in 22 consecutive epilepsy patients undergoing intracarotid amobarbital (Wada) testing and compared language lateralization measures obtained with the two procedures. FMRI used a single-word semantic decision task previously shown to activate lateralized language areas in normal adults. Correlation between the two tests was highly significant (r = 0.96; 95% CIs 0.90 to 0.98; p < 0.0001). These results validate the FMRI technique and suggest that "active" areas observed with this semantic processing task correspond to those underlying hemispheric dominance for language. This strong correlation observed supports the view that language lateralization is a continuous rather than a dichotomous variable. In addition to lateralization information, FMRI consistently demonstrated focal regions of activity in lateral frontal and temporo-parieto-occipital cortex. These functional maps may be helpful in defining the boundaries of surgical excisions.

Adolescent↗

PubMed1995

Lateralized human brain language systems demonstrated by task subtraction functional magnetic resonance imaging.

OBJECTIVE: To develop a procedure for noninvasive measurement of language lateralization with functional magnetic resonance imaging (MRI). DESIGN: Functional neuroimaging using time-series echo-planar MRI. SETTING: University medical center research facility. SUBJECTS: Five healthy, right-handed, young adults. MAIN OUTCOME MEASURES: Number of MRI voxels in left and right hemispheres showing task-related signal increases during two contrasting auditory processing tasks. The nonlinguistic task involved processing of pure tones, while the linguistic task involved processing of single words based on semantic content. RESULTS: The pure-tone processing task activated temporal lobe auditory areas and dorsolateral frontal regions bilaterally. Using this task as a control condition, the semantic processing task resulted in lateralized activity in distributed regions of the left hemisphere. A significant effect of task on intrahemispheric activity pattern was demonstrated in every subject. Results were reproduced in preliminary studies of test-retest reliability. CONCLUSIONS: The results demonstrate the lateralized anatomy of semantic linguistic systems in contrast to non-linguistic auditory sensory processors and introduce a task subtraction technique adapted for functional MRI as a noninvasive measure of language lateralization.

Adult↗

PubMed1995

Somatotopic mapping of the human primary motor cortex with functional magnetic resonance imaging.

We applied functional magnetic resonance imaging (FMRI) to map the somatotopic organization of the primary motor cortex using voluntary movements of the hand, arm, and foot. Eight right-handed healthy subjects performed self-paced, repetitive, flexion/extension movements of the limbs while undergoing echo-planar imaging. Four subjects performed movements of the right fingers and toes, while the remaining subjects performed movements of the right fingers and elbow joint. There was statistically significant functional activity in the left primary motor cortex in all subjects. The pattern of functional activity followed a topographic representation: finger movements resulted in signal intensity changes over the convexity of the left motor cortex, whereas toe movements produced changes either at the interhemispheric fissure or on the dorsolateral surface adjacent to the interhemispheric fissure. Elbow movements overlapped the more medial signal intensity changes observed with finger movements. Functionally active regions were confined to the cortical ribbon and followed the gyral anatomy closely. These findings indicate that FMRI is capable of generating somatotopic maps of the primary motor cortex in individual subjects.

Adult↗

PubMed1994

Functional magnetic resonance imaging of human auditory cortex.

Magnetic resonance imaging methods recently demonstrated regional cerebral signal changes in response to limb movement and visual stimulation, attributed to blood flow enhancement. We studied 5 normal subjects scanned while listening to auditory stimuli including nonspeech noise, meaningless speech sounds, single words, and narrative text. Imaged regions included the lateral aspects of both hemispheres. Signal changes in the superior temporal gyrus and superior temporal sulcus were observed bilaterally in all subjects. Speech stimuli were associated with significantly more widespread signal changes than was the noise stimulus, while no consistent differences were observed between responses to different speech stimuli. Considerable intersubject variability in the topography of signal changes was observed. These observations confirm the utility of magnetic resonance imaging in the study of human brain structure-function relationships and emphasize the role of the superior temporal gyrus in perception of acoustic-phonetic features of speech, rather than processing of semantic features.

Acoustic Stimulation↗

PubMed1994

Intrahemispheric localization of drawing dysfunction.

We evaluated drawing disability in 37 patients with right hemispheric stroke and in eight controls with no brain disease. Blinded evaluations included measures of overall recognizability and hemineglect. By mapping the CT lesions of patients, we found that damage to parieto-occipital cortex in poor drawers correlated with poor performance on a line bisection task whereas frontal, subcortical damage in poor drawers did not. We propose that drawing disability may be produced by visual-spatial dysfunction in patients with posterior lesions and by a disturbance of integrated motor function in those with frontal, subcortical damage.

Adult↗

PubMed1994

Effects of stimulus rate on signal response during functional magnetic resonance imaging of auditory cortex.

Functional magnetic resonance imaging (FMRI) detects focal MRI signal changes in brain tissue that are believed to result from changes in neuronal activity. We describe the dependence of this response in auditory cortex on the rate of presentation of simple speech stimuli. Speech syllables were presented to five normal subjects at rates ranging from 0.17 to 2.5 Hz, while the subjects performed a phoneme discrimination task. Regions studied with FMRI during this task included the lateral aspect of both temporal lobes. All subjects showed bilateral superior temporal lobe MRI signal increases that were coincident with stimulus presentation and performance of the task. The magnitude of this response increased in a monotonic, non-linear manner with increasing stimulus rate. This rate-response relationship was nearly identical in right and left hemispheres. The relationship may reflect metabolic activity integrated over time and subject to non-linear characteristics of neuronal recovery or blood flow regulation. The dependence of response magnitude on stimulation rate supports the hypothesis that the FMRI phenomenon indirectly reflects neuronal metabolic activity. The measures provided here should assist in the design of optimal activation strategies for the human auditory cortex.

Adult↗

PubMed1994

Functional magnetic resonance imaging of somatosensory stimulation.

Functional magnetic resonance imaging (FMRI) has detected changes in regional cerebral blood flow and volume in response to motor movements, visual stimuli, and auditory stimuli in each of their respective primary cortices. This experiment was conducted to determine whether signal changes in the somatosensory cortex secondary to tactile stimulation could be demonstrated. The palm of the right hand was periodically stimulated while the subject was undergoing echo-planar imaging with a 1.5-T magnetic resonance scanner equipped with local gradient and radio frequency coils. Sagittal and coronal images of 10- to 15-mm slice thickness were selected to include the postcentral gyrus and surrounding regions. Temporally correlated signal changes of 1% to 5% occurred in the peri-rolandic region in each of six subjects. The time course of signal changes was comparable to that found in other primary sensory and motor cortices. The results provide preliminary evidence of the sensitivity of FMRI to activation of the somatosensory cortex with tactile stimulation and support FMRI as a promising noninvasive technique for study of the functional organization and integrity of the cerebrum.

Adult↗

PubMed1993

Functional magnetic resonance imaging of complex human movements.

Functional magnetic resonance imaging (FMRI) is a new, noninvasive imaging tool thought to measure changes related to regional cerebral blood flow (rCBF). Previous FMRI studies have demonstrated functional changes within the primary cerebral cortex in response to simple activation tasks, but it is unknown whether FMRI can also detect changes within the nonprimary cortex in response to complex mental activities. We therefore scanned six right-handed healthy subjects while they performed self-paced simple and complex finger movements with the right and left hands. Some subjects also performed the tasks at a fixed rate (2 Hz) or imagined performing the complex task. Functional changes occurred (1) in the contralateral primary motor cortex during simple, self-paced movements; (2) in the contralateral (and occasionally ipsilateral) primary motor cortex, the supplementary motor area (SMA), the premotor cortex of both hemispheres, and the contralateral somatosensory cortex during complex, self-paced movements; (3) with less intensity during paced movements, presumably due to the slower movement rates associated with the paced (relative to self-paced) condition; and (4) in the SMA and, to a lesser degree, the premotor cortex during imagined complex movements. These preliminary results are consistent with hierarchical models of voluntary motor control.

Adult↗

PubMed1992

The topography of callosal reading pathways. A case-control analysis.

Lesion topography and reading ability were analysed in 17 patients with dominant posterior cerebral artery territory infarction. Patients with dominant posterior cerebral artery infarction in whom reading was unaffected served as an anatomical control group. Normal readers had lesions in the medial and ventral occipital lobe, sparing dorsal white matter pathways and the ventral temporal lobe. Global and permanent alexia occurred only with additional injury to the splenium, forceps major or white matter above the occipital horn of the lateral ventricle. These data suggest that callosal pathways mediating reading lie above the occipital horn and have little connection with the ventromedial occipital region. Patients with 'spelling dyslexia' had large lesions of the ventral temporal lobe involving cortical regions believed to participate in later stages of visual processing. These findings provide a framework for the prediction of dyslexia type and severity based on lesion topography.

Adult↗

PubMed1992

Left hemiparalexia.

Three patients with left splenial lesions made paralexic errors restricted to the left end of words. Errors appeared more frequently when a correct response was highly dependent on the initial letter of the stimulus. One patient had full visual fields with hemialexia affecting the left visual field. The other two patients had complete right hemianopia. We attribute left-sided reading errors in the hemianopic patients to a retinotopically restricted disconnection pattern that selectively disrupts transfer of information originating from the peripheral left visual field. Functional resistance of the more numerous transcallosal projections representing visual field adjacent to the vertical meridian may account for such a pattern. The emergence of positional reading errors from retinotopically restricted left hemifield disconnection suggests that callosal information transfer during normal reading may primarily involve elemental sensory rather than lexical/semantic information.

Adult↗

PubMed1990

Visual hemineglect and hemihallucinations in a patient with a subcortical infarction.

An alcoholic patient with a mainly right subcortical infarction developed contralateral left-sided neglect and then, in the context of alcohol withdrawal, unilateral hallucinations in the non-neglected right hemispace. It is hypothesized that an interruption of the striatocortical pathways could prevent the right hemisphere from representing appropriately internally produced stimuli.

Adult↗