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PubMed2005

Functional motor compensation in amyotrophic lateral sclerosis.

The present study investigated the fMRI correlates of functional compensation/neural reorganization of the motor system in patients with amyotrophic lateral sclerosis (ALS). The hypothesis was that ALS patients would recruit additional brain regions compared with controls in a motor task and that activity in these regions would vary as a function of task difficulty. Patients and controls executed a motor task with two sequences (a simple and a more difficult one) of consecutive button presses. Patients and controls both activated brain regions known to be involved in motor execution and control. Activity in ipsilateral motor areas as well as difficulty-related activity in the left cerebellum could only be observed in patients. The behavioral data indicated that the motor task was much more difficult for patients than for controls. At nearly equal difficulty the observed patterns of hemodynamic activity in controls were very similar to those observed in ALS. The findings suggest that functional compensation in ALS relies on existing resources and mechanisms that are not primarily developed as a consequence of the lesion.

Adult↗
PubMed1999

Sagittal computerized tomography reconstruction of the lateral nasal wall for functional endoscopic sinus surgery.

Coronal computerized tomography (CT) scanning is imperative in the preoperative work-up for functional endoscopic sinus surgery (FESS). This study describes additional information provided by lateral CT reconstruction with special attention to the (naso-) frontal recess. Thin axial scans were taken from 10 patients suffering from chronic rhinosinusitis. This procedure avoided artefacts from dental fillings on the computerized reconstructions. The common landmarks of the lateral nasal wall as described in the surgical anatomy of FESS were easily identified on sagittal views. The average angulation of the sagittal plane from the midline required to obtain optimal images of the frontal recess was antero-posteriorly 8.7 degrees (SD, 2.4), cranio-caudally 7.7 degrees (SD, 2.6). Size and condition of the frontal recess could be demonstrated. Variations of the angle between frontal sinus and ethmoid infundibulum appeared to depend on the anterior projection of the frontal sinus and may give an indication as to the optimal endoscopic angle for visualization of the frontal ostium. Sagittal reconstructions provide information for better spatial orientation particularly in the plane of the surgical approach and may help to diagnose underlying functional changes of chronic frontal sinusitis.

Chronic Disease↗
PubMed1995

Corticotropin-releasing factor injected into the lateral septum improves memory function in rats.

The present study investigated the role of corticotropin-releasing factor (CRF) in the lateral septum in modulating the memory process and in regulation of the rearing response in rats. Rats were bilaterally cannulated in the lateral septum and CRF was injected right after training of an inhibitory avoidance task. Retention performance and rearing measure were conducted 24 hr later. In another experiment, CRF was also injected into the lateral septum and rearing response measured immediately afterwards. Results indicated that CRF, at moderate doses, markedly enhanced memory retention and decreased rearing response in rats. The latter effect was no longer observed 24 hr after CRF injection. These findings support the notion that the lateral septum is involved in the memory process and emotional expression. These results, together with earlier reports, also suggest that CRF probably produces a consistent facilitatory effect upon memory consolidation and inhibitory effect upon exploration within the limbic system in rats.

Animals↗
PubMedDate not supplied

'Hidden lamination' in the dorsal lateral geniculate nucleus: the functional organization of this thalamic region in the rat.

The cyto-and myeloarchitecture of the rat's dorsal lateral geniculate nucleus (dLGN) display none of the laminar features characteristic of this thalamic region in carnivores and primates. Despite this, the rodent's nucleus contains a segregation of functionally and ocularly distinct afferents--organizational properties manifested in the prominent lamination of these other mammalian forms. The rat's dLGN can be divided into two main regions: an inner core and an outer shell. The inner core contains two ocular laminae receiving direct retinotopic projections from the contralateral nasal and ipsilateral temporal retinae, mapping the contralateral visual hemifield. The outer shell receives a retinotopic projection from the complete contralateral retina only, the representation of the ipsilateral hemifield being extremely compressed at the medial edge of this lamina. The retinotopic maps in these three ocular laminae (contra, ipsi, contra) are in conjugate register, so that lines of projection course rostro-ventro-medially from the optic tract at the thalamic surface through these laminae. Three morphologically distinct retinal ganglion cell types project to the dLGN, and the axons of these ganglion cells are partially segregated within the optic tract in anticipation of their segregation within the nucleus, where they terminate at distinct locations along the lines of projection. Type I and III cells terminate in the inner core of the nucleus, while type II and III cells terminate in the outer shell. The outer shell also receives a direct projection from the superior colliculus. These characteristics of the afferent termination within the rat's dLGN support the view of a general mammalian plan for the organization of this thalamic region, and provide a basis for further experimentation to test speculations about potentially homologous subdivisions of this nucleus. Conclusions regarding functionally analogous pathways are proposed with less confidence, due to the paucity of definitive evidence for physiologically distinct cell classes. The type I cells in the rat's retina are the likely homologues of the cat's alpha-cell. Geniculocortical relay cells driven by them have properties similar to the cat's Y-cell. The inner core of the nucleus then may transmit information of a Y-like nature onto striate cortex. The outer shell of the rat's nucleus, a portion of which receives collicular as well as retinal innervation, may convey W-like information onto striate cortex. The rat's retinogeniculate projection appears to be lacking a beta-cell-like pathway that may subserve X-cell function altogether.

Animals↗
PubMedDate not supplied

Early maternal and child influences on children's later independent cognitive and social functioning.

The present study examined whether parenting and child characteristics of 2- and 3 1/2-year-old children had common paths of influence on their 4 1/2-year independent cognitive and social functioning. Structural equation modeling was guided by hypotheses that assumed children's later independence is facilitated by specialized parental support in early social interactions. To address the importance of variability in early development for understanding children's later independence, we included 104 term and 185 preterm children, as they are known to differ in early skills. As predicted, mothers' maintaining of children's interests indirectly supported 4 1/2-year cognitive and social independence through a direct, positive influence on 2- and 3 1/2-year skills. Directiveness positively supported children's early cognitive and responsiveness skills but by 3 1/2 years, high levels of this behavior had a direct, negative influence on their cognitive and social independence at 4 1/2 years. Whereas high levels of maintaining interests across these ages support later independence, directiveness needs to decrease in relation to children's increasing competencies. Results support a theoretical framework that emphasizes the importance of the social context for understanding the origins of children's later independent functioning.

Age Factors↗
PubMed1978

Duration of task: an indicator of differentiation between motoneuron pools.

Sustaining an isometric contraction at a percentage of maximum contraction value prior to fatigue is significantly longer for the dominant arm than the non-dominant arm as reanalysis of data shows. This peripheral motor parameter which differentiates handedness as reflected in motoneuron pools may clarify the relationship between contralateral motor function and functional cerebral lateralizations.

Arm↗
PubMed2000

Variations in subject pool as a function of earlier or later participation.

Data were obtained from 113 participants in a university subject pool during a 16-wk. semester. Without knowing the purpose of the study, participants self-selected to participate earlier (Weeks 3 and 4: n = 63) or later (Weeks 15 or 16) n = 50). Variations in scores on the NEO Personality Inventory--Revised, the Crowne-Marlowe Social Desirability Scale, the General Expectancy of Success Scale, the Shipley Institute of Living Scale, self-reported SATs and GPAs, and a measure of academic self-efficacy as a function of earlier or later participation were examined. Multivariate analysis of variance indicated that early participants differed significantly from later participants but not in predicted ways. Earlier participants scored higher on NEO PI-R Neuroticism; specifically men (n = 15) and women (n = 48) scored higher on Hostility, and women scored higher on Depression and Self-consciousness. An additional significant difference occurred for self-reported SAT Verbal scores for men, which were significantly higher for later participants. These temporal variations may represent confounds in research using university subject pools.

Adolescent↗
PubMed2003

Functional imaging of the human lateral geniculate nucleus and pulvinar.

In the human brain, little is known about the functional anatomy and response properties of subcortical nuclei containing visual maps such as the lateral geniculate nucleus (LGN) and the pulvinar. Using functional magnetic resonance imaging (fMRI) at 3 tesla (T), collective responses of neural populations in the LGN were measured as a function of stimulus contrast and flicker reversal rate and compared with those obtained in visual cortex. Flickering checkerboard stimuli presented in alternation to the right and left hemifields reliably activated the LGN. The peak of the LGN activation was found to be on average within +/-2 mm of the anatomical location of the LGN, as identified on high-resolution structural images. In all visual areas except the middle temporal (MT), fMRI responses increased monotonically with stimulus contrast. In the LGN, the dynamic response range of the contrast function was larger and contrast gain was lower than in the cortex. Contrast sensitivity was lowest in the LGN and V1 and increased gradually in extrastriate cortex. In area MT, responses were saturated at 4% contrast. Response modulation by changes in flicker rate was similar in the LGN and V1 and occurred mainly in the frequency range between 0.5 and 7.5 Hz; in contrast, in extrastriate areas V4, V3A, and MT, responses were modulated mainly in the frequency range between 7.5 and 20 Hz. In the human pulvinar, no activations were obtained with the experimental designs used to probe response properties of the LGN. However, regions in the mediodorsal right and left pulvinar were found to be consistently activated by bilaterally presented flickering checkerboard stimuli, when subjects attended to the stimuli. Taken together, our results demonstrate that fMRI at 3 T can be used effectively to study thalamocortical circuits in the human brain.

Adult↗
PubMed2005

Modality-specific cognitive function of medial and lateral human Brodmann area 6.

Despite the fact that human Brodmann area 6 (BA6), a traditional "motor" area, is active during higher motor control involving various cognitive operations, the functional specialization within BA6 in the cognitive domain is essentially unknown. Furthermore, its functional relevance in cognition has been questioned because brain activity in BA6 during cognitive tasks has often been explained away as a concomitant, latent motor process. Therefore, we examined the structural-functional relationship of human BA6 in nonmotor cognitive functions and its functional relevance using both functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS). Subjects performed mental-operation (MO) tasks in which they serially updated verbal and spatial mental representations (MO-v and MO-s). In the fMRI experiments, activity in the medial BA6 was more increased in MO-v, whereas the activity in the lateral BA6 in both hemispheres was more in MO-s. Low-frequency rTMS to the medial BA6 disrupted only the performance of MO-v, whereas rTMS to the lateral BA6 in both hemispheres disrupted only MO-s. Hence the converging results demonstrate a functional double dissociation in which medial BA6 has a critical role in updating verbal information and lateral BA6 has a role in updating spatial information. The present study provides direct physiological evidence of modality-specific cognitive function within human BA6.

Adult↗
PubMed1995

Neurotensin in the lateral hypothalamic area: origin and function.

The origin of neurotensin in the lateral hypothalamus was investigated by means of fluorescent retrograde tract tracing and neurotensin-like immunoreactivity. Following fluorescent retrograde tract tracing with FluoroGold combined with neurotensin immunohistochemistry in the rat brain, numerous neurotensin-immunoreactive neurons with projections to the posterior lateral hypothalamic area were identified in the central nucleus of the amygdala, perifornical area and the parabrachial nucleus. Fewer numbers of neurotensin-positive neurons with projections to the lateral hypothalamic area were observed in the bed nucleus of the stria terminalis, lateral septal nucleus, medial preoptic area, peri- and paraventricular nuclei of the hypothalamus, anterior lateral hypothalamic area and dorsal raphe nucleus. In addition, the role of neurotensin in the modulation of autonomic regulatory input from the insula was investigated. The lateral hypothalamic area was surveyed for single units responding to electrical stimulation (500-900 microA, 0.5 Hz) of sites in the insular cortex from which cardiovascular pressor or depressor responses could be elicited. These units were tested for the influence of neurotensin on responses to stimulation of the insular cortex. Of 60 spontaneously firing neurons, 27 units responded to electrical stimulation of cardiovascular sites in the insula. Of the units responding to stimulation of cardiovascular sites in the insula, 14 units showed excitation only, 10 units showed excitation followed by inhibition and three units showed inhibition. Iontophoresis of 0.1-1.0 mM neurotensin (25-100 nA, pH 5.0-6.0) potentiated six of the excitatory responses and showed no effect on the inhibitory responses. In addition, nine neurons showed an increase in spontaneous activity with iontophoresis of neurotensin. Of these neurons, three were excited by insular stimulation and six did not respond. These findings indicate the likely origin of neurotensin in the lateral hypothalamic area and demonstrate that neurotensin has a role in the modulation of some of the cardiovascular regulatory input from the insular cortex.

Amygdala↗
PubMed2006

Hemispheric asymmetry of sulcus-function correspondence: quantization and developmental implications.

Spatial covariances between the geometric centers of human occipital sulci and visual functional areas were calculated to reduce the spatial variance of functional-area locations between subjects. Seven visual areas in each occipital hemisphere were retinotopically mapped, using horizontal- and vertical-meridian stimuli and (15)O PET in 11 subjects. Sulcal locations were determined using anatomic brain models derived from high-resolution MRI images. Location variability for sulci and functional areas was similar in magnitude, with average standard deviations of (2.7x, 5.3y, 5.7z) mm and (4.3x, 5.4y, 5.3z) mm, respectively. Sulcal locations were predictive of functional-area locations (i.e., significant spatial covariance) in the minority of structure-function pairings tested (25 of 168). Location variability was reduced by an average of 27% for functional areas showing significant covariation with sulcal features. Early-developing sulci were stronger predictors of functional-area location than late-developing sulci. Sulcus-function covariance was stronger in the left occipital lobe than in the right occipital lobe. Notably, the left calcarine fissure demonstrated powerful covariances with functional areas in both hemispheres, suggesting that it serves as a developmental "anchor" for functional areas in the occipital cortex. These findings support the hypothesis that hemispheric lateralization of function is reflected in the strength of correspondence between cortical surface anatomy and function.

Adolescent↗
PubMed1983

Asymmetry of perception in free viewing of chimeric faces.

We have devised a new free-vision task to index functional cerebral asymmetry for processing facial characteristics. Confirming its sensitivity to properties of lateralized hemispheric functions, left- and right-handers were clearly differentiated on this task with respect to several aspects of performance that conform with known differences between handedness groups in hemispheric asymmetry. Additionally, there were highly reliable and stable individual differences in perceptual asymmetries within handedness. Analyses of items in the task revealed that most of the differences between items in the asymmetries they elicited were random.

Brain↗
PubMed2003

Comparison of relative renal function by renal scintigraphy and lateralized creatinine clearance in children with bilateral vesicoureteral reflux.

OBJECTIVES: To evaluate the relative renal function on preoperative and postoperative renal scintigraphy with lateralized creatinine clearance. Multiple factors affect renal blood flow and glomerular filtration that alter the relative renal function calculated by renal scintigraphy. The relative renal function according to renal scintigraphy in children with bilateral vesicoureteral reflux has not been compared with lateralized creatinine clearance. METHODS: We retrospectively reviewed the charts of 45 children treated surgically for bilateral vesicoureteral reflux. The average age at time of reimplantation was 5.3 years. Bilateral ureteral catheters were placed intraoperatively. Lateralized creatinine clearance was measured with 24-hour urine collections postoperatively from each catheter. Bladder catheterization was not performed during the renal scans. RESULTS: Thirty-six of 45 children had preoperative 1 to 3-minute relative renal function assessed by scintigraphy, 28 had a postoperative assessment, and 24 had both. Preoperative relative renal function ranged between 51% and 94% (mean 61.3%) in the higher functioning kidney. Postoperative renal function ranged from 47% to 90% (mean 60.5%) in the higher functioning kidney. A strong correlation existed between preoperative relative renal function and lateralized creatinine clearance (P <0.0001). Similarly, a significant correlation existed between the postoperative assessment and lateralized creatinine clearance (P <0.0003). No significant difference occurred between the preoperative and postoperative 1 to 3-minute relative renal function (P = 0.3552). CONCLUSIONS: The 1 to 3-minute relative renal function determined by renal scintigraphy accurately reflects the relative renal function determined by lateralized creatinine clearance. Bladder catheterization does not appear necessary for accurate determination of relative renal function by renal scan even in the presence of bilateral reflux.

Adolescent↗
PubMed1977

Bilateral renal artery stenosis and renovascular hypertension.

Experience with the diagnostic evaluation and operative management of 38 hypertensive patients having bilateral renal revascularization is presented. Twenty-four patients had atherosclerotic occlusions and 14 had fibromuscular dysplasia. Renal vein renin assays (RVRA) and/or split renal function studies (SRFS) were performed in 37 of the 38 patients before operation. Although RVRA was negative in 29 percent and SRFS negative in 31 percent, 24 of 26 patients (92 percent) having both tests done had at least one positive study. Twenty-one patients had simultaneous bilateral repairs and 12 had staged bilateral reconstructions. The incidence of technical failures in these two groups was 21 and 9 percent, respectively. Excluding three uncorrected technical failures and two patients with recurrent branch renal artery lesions, 90 percent of patients with atherosclerosis and all patients with fibromuscular dysplasia had a favorable blood pressure response to operation. This study supports the use of both RVRA and SRFS in the diagnostic evaluation of hypertensive patients with renal artery stenosis. If these functional tests lateralize to one side, repair of that side only is recommended. If the functional studies do not lateralize, operation is suggested only when hypertension is severe and is not controlled readily with medications. In this circumstance reconstruction of the side that appears to be diseased most severely is recommended. Contralateral repair is undertaken only when hypertension persists and when repeat functional studies lateralize to the unoperated side.

Adult↗