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At least 919 records · Page 51Linked to original sources
PubMed2005

Modification of the functional reach test: analysis of lateral and anterior functional reach in community-dwelling older people.

The purpose of this study was to evaluate the validity and reproducibility of the modified lateral functional reach (FR), and to examine the associations between a variety of functional variables and the FR in community-dwelling older people (>65 years of age). A total of 383 aged Japanese participated in this study at the rural district Kahoku, Kochi, Japan, in 2002. The average age of the subjects was 78.6 years. The activity of daily living (ADL) and mental status were measured as outcomes. FR (anterior and lateral) and timed up and go (TUG) were measured as predictors. The test-retest reliability of lateral FR between the first and second measurement was very consistent. Subjects with greater lateral FR had higher basic and instrumental ADL (IADL) scores than did those with shorter lateral FR. However, there was no significant relationship between anterior FR and ADLs. The lateral FR of participants with depression was shorter than in those without depression, while the anterior FR did not correlate with the participants' scores on the geriatric depression scale (GDS). Lateral FR should be considered as a new, alternative means of assessing geriatric social activity and mental status in the elderly.

Activities of Daily Living↗
PubMed2005

Dynamic evaluation of contact pressure and the effects of graft harvest with subsequent lateral release at osteochondral donor sites in the knee.

PURPOSE: To dynamically evaluate contact pressure about the periphery of the lateral femoral condyle in intact knees, to qualify the effects of osteochondral donor graft harvest on this contact pressure, and to quantify the effects of lateral release on contact pressure after graft harvest. TYPE OF STUDY: Cadaveric analysis. METHODS: Digital electronic pressure-sensing cells were used to measure contact pressure over the periphery of the lateral femoral condyle in 10 fresh-frozen knee specimens. Nonweightbearing resistive extension was simulated as the knees were placed through a functional range of motion. Dynamic pressure readings were evaluated over intact cartilage, around the rims of four 5-mm osteochondral defects, and after lateral release. RESULTS: The pressure cells were all subjected to contact pressures as the knees were placed through a functional range of motion. Average maximal contact pressure progressed distally as the knees were flexed. The creation of 5-mm osteochondral defects did not lead to a significant increase in rim stress concentration over the surrounding cartilage. Lateral release resulted in small decreases in contact pressure over the osteochondral defects. CONCLUSIONS: The creation of 5-mm donor defects about the lateral aspect of the lateral femoral condyle does not lead to significant alterations in local contact pressure. CLINICAL RELEVANCE: Our biomechanical findings may have important implications relating to cartilage restoration using osteochondral autografting procedures. Donor-site morbidity may be minimized if donor-site defects are limited to 5 mm and smaller.

Amputation, Surgical↗
PubMed2006

Zinc release in the lateral nucleus of the amygdala by stimulation of the entorhinal cortex.

Zinc release in the lateral nucleus of the amygdala was examined using rat brain slices. The lateral and basolateral nuclei in the amygdala were evidently stained by Timm's sulfide-silver staining method. When the amygdala including both the nuclei was stimulated with 100 mM KCl by means of in vivo microdialysis, extracellular zinc concentration was increased significantly. Zinc release in the lateral nucleus of the amygdala innervated by the entorhinal cortex was next examined in brain slices double-stained with zinc and calcium indicators. Extracellular zinc signal (ZnAF-2) in the lateral nucleus was increased with intracellular calcium signal (calcium orange) during delivery of tetanic stimuli to the entorhinal cortex. Both the increases were completely inhibited by addition of 1 micro M tetrodotoxin, a sodium channel blocker. Furthermore, calcium signal in the lateral nucleus during delivery of tetanic stimuli to the entorhinal cortex was increased in the presence of 10 micro M CNQX, an AMPA/KA receptor antagonist, and this increase was facilitated by addition of 1 mM CaEDTA, a membrane-impermeable zinc chelator. The present study suggested that zinc is released in the lateral nucleus of the amygdala by depolarization of the entorhinal neurons. In the lateral nucleus, zinc released may suppress the increase in presynaptic calcium signal.

Amygdala↗
PubMed2004

Key differences between lateral and apical branching in hyphae of Neurospora crassa.

We examined in fine detail growth kinetics and intracellular events during lateral and apical branching in hyphae of Neurospora crassa. By high-resolution video-enhanced light microscopy, we found remarkable differences in the events preceding lateral vs apical branching. While apical branching involved a significant disturbance in the apical growth of the parental hypha, lateral branching occurred without any detectable alterations in the growth of the parental hypha. Prior to the emergence of a lateral branch, an incipient Spitzenkörper was formed about 12-29 microm behind the apex. Lateral branch formation did not interfere with the elongation rate of the primary hypha, the shape of its apex or the behavior of its Spitzenkörper. In sharp contrast, apical branching was preceded by marked changes in physiology and morphology of the parental hypha and by a sharp drop in elongation rate. The sequence involved a cytoplasmic contraction, followed by a retraction, dislocation, and disappearance of the Spitzenkörper; hyphal elongation decreased sharply and a transient phase of isotropic growth caused the hyphal apex to round up. Growth resumed with the formation of two or more apical branches, each one with a Spitzenkörper formed by gradual condensation of phase-dark material (vesicles) around an invisible nucleation site. The observed dissimilarities between lateral and apical branching suggest that these morphogenetic pathways are triggered differently. Whereas apical branching may be traced to a sudden discrete disruption in cytoplasmic organization (cytoplasmic contraction), the trigger of lateral branching probably stems from the subapical accumulation of wall precursors (presumably vesicles) reaching a critical concentration.

Cell Wall↗
PubMed2006

Effect of blood pressure instrument and cuff side on blood pressure reading in pregnant women in the lateral recumbent position.

BACKGROUND: Hydrostatic forces affect non-invasive blood pressure measurement in the lateral position. This study assessed the extent of this effect with the mercury column sphygmomanometer and Dinamap oscillometric instrument as well as different recommendations for comparing supine and lateral blood pressure measurements. METHOD: Thirty-two term pregnant women were studied in the antenatal clinic. Blood pressure was recorded from both arms in the right lateral and supine recumbent positions, using the sphygmomanometer and Dinamap. RESULTS: Blood pressure in the uppermost arm while lateral was lower than supine by a mean 10 mmHg or more. Systolic, mean and diastolic pressures in the dependent arm while lateral were higher than supine by a mean (SD) 3.1 (6.8)mmHg, 5.6 (6.8)mmHg, and 6.9 (8.7)mmHg using the sphygmomanometer and 3.8 (8.1)mmHg, 3.2 (7.1)mmHg, and 1.9 (5.3)mmHg using the Dinamap. Systolic, mean and diastolic pressure values calculated as the average taken from both arms in the lateral position were lower than supine by a mean (SD) 3.5 (7.5)mmHg, 3.9 (4.7) mmHg, and 4.1 (5.8)mmHg using the sphygmomanometer and 4.6 (6.0)mmHg, 4.9 (4.4)mmHg, and 4.8 (4.4)mmHg using the Dinamap. Corresponding blood pressure readings were always higher using the Dinamap than the sphygmomanometer. CONCLUSIONS: In normotensive non-labouring term pregnant women, the use of the dependent arm or an average blood pressure from both arms while in the lateral position will give a closer reading to supine blood pressure than the use of the uppermost arm. However, use of the dependent arm is simpler.

Adult↗
PubMed2006

Lateral graft type 1 tympanoplasty using AlloDerm for tympanic membrane reconstruction in children.

OBJECTIVES: To describe the lateral graft type 1 tympanoplasty technique using AlloDerm for tympanic membrane reconstruction in children and to compare its surgical and audiometric outcomes with the traditional underlay type 1 tympanoplasty. METHODS: The records of 34 consecutive children undergoing type 1 tympanoplasty between 2004 and 2005 were reviewed; 18 received lateral graft tympanoplasty with AlloDerm and 16 received underlay tympanoplasty (8 AlloDerm and 8 temporalis fascia). Pre- and post-surgical audiograms, speech reception threshold, closure rate and complication rate were evaluated using one-way and repeated measures ANOVAs. RESULTS: Children who underwent lateral graft type 1 tympanoplasty pre-operatively had larger tympanic membrane perforations, worse pure tone averages, air bone gaps and speech reception thresholds as compared with children undergoing underlay type 1 tympanoplasty (P<0.001). Pure tone averages and air bone gaps improved significantly with surgery in both lateral and underlay type 1 tympanoplasty groups (P<0.05), with both groups achieving comparable postoperative audiometric outcomes (P>0.01). The lateral graft group demonstrated a higher perforation closure rate (94%) as compared with both underlay groups (88%). Complication rates were virtually non-existent. CONCLUSIONS: Despite larger perforations and worse pre-operative audiometric scores, children who underwent lateral graft type 1 tympanoplasty achieved comparable postoperative audiometric results and perforation closure rates as compared with children who underwent underlay type 1 tympanoplasty. Results suggest that lateral graft type 1 tympanoplasty using AlloDerm is effective for tympanic membrane reconstruction in children and should be used when temporalis fascia is not available or the extent of the perforation limits its use.

Adolescent↗
PubMed2005

Finite element analysis of the temporomandibular joint during lateral excursions of the mandible.

One of the most significant characteristics of the temporomandibular joint (TMJ) is that it is in fact composed of two joints. Several finite element simulations of the TMJ have been developed but none of them analysed the different responses of its two sides during nonsymmetrical movement. In this paper, a lateral excursion of the mandible was introduced and the biomechanical behaviour of both sides was studied. A three-dimensional finite element model of the joint comprising the bone components, both articular discs, and the temporomandibular ligaments was used. A fibre-reinforced porohyperelastic model was introduced to simulate the behaviour of the articular discs, taking into account the orientation of the fibres in each zone of these cartilage components. The mandible movement during its lateral excursion was introduced as the loading condition in the analysis. As a consequence of the movement asymmetry, the discs were subjected to different load distributions. It was observed that the maximal shear stresses were located in the lateral zone of both discs and that the lateral attachment of the ipsilateral condyle-disc complex suffered a large distortion, due to the compression of this disc against the inferior surface of the temporal bone. These results may be related with possible consequences of a common disorder called bruxism. Although it would be necessary to perform an exhaustive analysis of this disorder, including the contact forces between the teeth during grinding, it could be suggested that a continuous lateral movement of the jaw may lead to perforations of both discs in their lateral part and may damage the lateral attachments of the disc to the condyle.

Bruxism↗
PubMedDate not supplied

Anatomy of the posterior antebrachial cutaneous nerve: practical information for the surgeon operating on the lateral aspect of the elbow.

PURPOSE: To investigate the anatomic relationships of the posterior antebrachial cutaneous nerve (PABCN) to anatomic landmarks on the lateral side of the elbow. METHODS: The PABCN was explored in 30 cadaveric upper extremities. Distances were noted from easily identifiable structures including the lateral epicondyle, the lateral intermuscular septum, and the radial nerve. RESULTS: The path of the PABCN follows the spiral groove initially, diverging as the radial nerve pierces the lateral intermuscular septum. The PABCN emerges from the posterior compartment through a hiatus in the deep fascia at a mean of 6.6 cm proximal to the lateral epicondyle and passes a mean of 2.1 cm anterior to the lateral epicondyle. CONCLUSIONS: The anatomic relationships determined in this study should enable the surgeon to avoid injuring the PABCN when performing surgery in the lateral elbow region.

Aged↗
PubMed2005

Validity of the lateral gliding test as tool for the diagnosis of intervertebral joint dysfunction in the lower cervical spine.

OBJECTIVE: To determine if the lateral gliding test for the cervical spine is a valid clinical test compared with radiological assessment as a tool for the diagnosis of intervertebral joint dysfunctions in the lower cervical spine in patients presenting with mechanical neck pain. METHODS: Twenty-five patients with mechanical neck pain presenting with an asymmetry of at least 5 degrees between left and right cervical lateral flexion and diagnosed with an intervertebral joint dysfunction in the lower cervical spine based on the lateral gliding test were studied. Two anterior-posterior x-rays were performed on each patient at maximum end-range of right and left cervical lateral flexion. The intervertebral motion was compared between the hypomobile side and the contralateral side at the level diagnosed as hypomobile by the lateral gliding test. RESULTS: The asymmetry between left and right cervical lateral flexion motion was 7.64 degrees +/- 2.25 degrees (P = .001). Fourteen patients were diagnosed with intervertebral dysfunctions on the right side, whereas 11 patients showed cervical hypomobility on the left. Joint dysfunction at the C3 vertebra was the most prevalent (n = 16), followed by the dysfunction at the C4 vertebra (n = 9). The intervertebral radiological motion at the hypomobile side (mean 19.1, SD 2.1 mm) was 3.44 +/- 1.9 mm less than the intervertebral radiological motion at the contralateral side (mean 22.6, SD 2.5 mm) with P = .002. CONCLUSIONS: The lateral gliding test for the cervical spine was as good as a radiological assessment for the diagnosis of intervertebral dysfunctions in the lower cervical spine.

Adult↗
PubMed2006

A convex lateral tibial plateau for knee replacement.

Unicompartmental knee replacements have not performed as well in the lateral compartment as in the medial. This may be because the tibial components have flat or slightly concave surfaces which match the medial plateau but not the convex lateral plateau. The aim of this study was to find the optimal radius for a convex lateral tibial component. Twelve normal lateral tibial plateau were retrieved at knee replacement, and their surface contour in their mid sagittal plane was determined. The optimal circle was fitted and its radius measured. A series of different shaped tibial components were superimposed. From published information about the position of the femoral condyle relative to the tibia in different degrees of flexion, the flexion gap at these angles was determined. The average radius of the lateral tibial plateau was 40 mm. However, as the surface was polyradial it was not clear if this average radius would be optimal. In full flexion, a flat tibial plateau distracted the knee by 8 mm (p<0.001). A 75 mm radius spherical tibial plateau did not alter the knee kinematics significantly and gave rise to a change in joint distraction of 1.5 mm. Spherical tibial plateau of 50 mm and 25 mm radii significantly altered knee kinematics (p<0.001) and resulted in changes in distraction of 3 mm and 4 mm respectively. The optimal shape for a unicompartmental lateral tibial plateau is likely to be a spherical dome with radius of about 75 mm. The incorporation of this shape in the lateral side of a total knee replacement might improve its flexion.

Femur↗
PubMed2005

Stimulation of the lateral hypothalamus produces antinociception mediated by 5-HT1A, 5-HT1B and 5-HT3 receptors in the rat spinal cord dorsal horn.

The lateral hypothalamus is part of an efferent system that modifies pain at the spinal cord dorsal horn, but the mechanisms by which lateral hypothalamus-induced antinociception occur are not fully understood. Previous work has shown that antinociception produced from electrical stimulation of the lateral hypothalamus is mediated in part by spinally projecting 5-hydroxytryptamine (5-HT) neurons in the ventromedial medulla. To further examine the role of the lateral hypothalamus in antinociception, the cholinergic agonist carbamylcholine chloride (125 nmol) was microinjected into the lateral hypothalamus of female Sprague-Dawley rats and nociceptive responses measured on the tail-flick and foot-withdrawal tests. Intrathecal injections of the selective 5-HT1A, 5-HT1B, 5-HT3 receptor antagonists, WAY 100135, SB-224289, and tropisetron, respectively, and the non-specific antagonist methysergide, were given. Lateral hypothalamus stimulation with carbamylcholine chloride produced significant antinociception that was blocked by WAY 100135, tropisetron, and SB-224289 on both the tail-flick and foot-withdrawal tests. Methysergide was not different from controls on the tail flick test, but increased foot-withdrawal latencies compared with controls. These results suggest that the lateral hypothalamus modifies nociception in part by activating spinally projecting serotonin neurons that act at 5-HT1A, 5-HT1B, and 5-HT3 receptors in the dorsal horn.

Animals↗
PubMed2005

Differential response dynamics of corticothalamic glutamatergic synapses in the lateral geniculate nucleus and thalamic reticular nucleus.

The corticothalamic feedback pathway provides excitatory synaptic input to both the thalamic reticular nucleus and the lateral geniculate nucleus. We studied excitatory postsynaptic currents elicited from corticothalamic stimulation in the visual sector of the thalamic reticular nucleus and the lateral geniculate nucleus to compare the response of these neurons to stimulation of their common input pathway. Using whole cell patch clamp recordings in ferret thalamic slices, we compared single excitatory postsynaptic current decay kinetics, presynaptic glutamate release dynamics through paired pulse facilitation and responses to corticothalamic train stimulation. We found that single thalamic reticular nucleus excitatory postsynaptic currents were significantly sharper than lateral geniculate nucleus responses. The mean thalamic reticular nucleus excitatory postsynaptic current decay constant (tau) was 4.9+/-0.5 ms, while the mean lateral geniculate nucleus excitatory postsynaptic current tau value was 11.8+/-0.8 ms. Presynaptic release dynamics as measured by responses to paired stimuli were conserved between the thalamic reticular nucleus and lateral geniculate nucleus. However, facilitating responses to train stimulation were markedly different between nuclei. Lateral geniculate nucleus responses showed proportionately larger facilitation (reaching 842.9 +/- 76.4% of excitatory postsynaptic current 1 amplitude) than thalamic reticular nucleus responses (reaching 223.1 +/- 44.0% of excitatory postsynaptic current 1 amplitude). These data indicate that while the corticothalamic pathway produces excitatory postsynaptic currents in both the thalamic reticular nucleus and lateral geniculate nucleus, other factors uniquely affect the functional integration of the inputs in each nucleus.

Action Potentials↗
PubMed2006

Differences in the effects of medial and lateral preoptic lesions on thermoregulation and sleep in rats.

The effects of the destruction of the medial preoptic area and the lateral preoptic area with N-methyl-d-aspartic acid on sleep-wakefulness, brain temperature and thermoregulation were studied in two groups of male Wistar rats. Electroencephalogram, electrooculogram and electromyogram, along with brain temperature, were recorded for 3 days, prior to the destruction of the medial preoptic area and the lateral preoptic area, and on the 7th and 21st days after the destruction of these areas. The thermoregulatory capacity of the rats was assessed by recording their brain temperature when they were exposed to severe cold (5+/-1 degrees C) and heat (37+/-1 degrees C) before and after the lesion. Though sleep was decreased after the destruction of both the medial preoptic area and the lateral preoptic area, paradoxical sleep was reduced only by the destruction of the medial preoptic area. Decrease in sleep after the medial preoptic area lesion was brought about by a decrease in the duration of the slow wave sleep episodes and the frequency of paradoxical sleep episodes. Decrease in sleep after the lateral preoptic area lesion was brought about by a decrease in the frequency of slow wave sleep episodes. There was a significant increase in brain temperature after the medial preoptic area lesion but not after the lateral preoptic area lesion. The rats with lesion in the medial preoptic area showed deficits in thermoregulation on exposure to cold, while those with the lateral preoptic area lesion showed deficits in heat defense ability. The present findings suggest that the medial preoptic area and the lateral preoptic area regulate sleep by different modalities and that there is an anatomical segregation of heat and cold defense functions within the basal forebrain.

Animals↗
PubMed2004

The effects of an edgeline on speed and lateral position: a meta-analysis.

This paper presents a meta-analysis of studies that have evaluated the effects of an edgeline on speed and lateral position of motorised road users. Together with many other study characteristics, 41 estimates of the effects of an edgeline on speed and 65 on lateral position were extracted from the studies. The results of the evaluation studies show a great variety in effects. Both negative and positive effects on speed and lateral position were found; amongst others, increases in speed up to 10.6 km/h, as well as decreases in speed up to 5.0 km/h, and shifts of the lateral position towards the centre of the road up to 30 cm, as well as shifts towards the edge of the road up to 35 cm. Further analyses resulted in the determination of study characteristics that influence the effects of an edgeline on speed and lateral position. It is concluded that the effects of an edgeline on speed are related to the presence of a centreline. Applying an edgeline to a road without a centreline increases the speed of road users, and replacing a centreline by an edgeline decreases the speed. Results with respect to adding an edgeline to a road with a centreline were unclear. Another conclusion is that shoulder width and road environment contribute to the effects of an edgeline on lateral position. In combination with wide shoulders or buildings and/or trees next to the road, edgelines lead to shifts of the lateral position towards the edge of the road, and in combination with narrow shoulders or open fields, edgelines lead to shifts towards the centre of the road.

Accidents, Traffic↗
PubMed2003

Accessory lateral rectus muscle in a patient with congenital third-nerve palsy.

PURPOSE: To report a case of accessory lateral rectus muscle in a patient with congenital third-nerve palsy. DESIGN: Observational case report. METHODS: An 18-year-old boy with left exodeviation, ptosis, pupil dilation, and limited adduction, supraduction, and infraduction of his left eye. Left lateral rectus muscle recession and medial rectus muscle resection were done. An orbital computed tomographic (CT) scan was obtained. RESULT: Intraoperatively, an accessory muscle was found under the lateral rectus muscle. Postoperatively, the orbital CT scan showed accessory lateral rectus muscle located in the medial side of the lateral rectus muscle. CONCLUSION: Accessory lateral rectus muscle was demonstrated in a patient with congenital third-nerve palsy using lateral rectus muscle surgery and an orbital CT scan.

Adolescent↗
PubMed1999

Electromyographic activity of the human lateral pterygoid muscle during contralateral and protrusive jaw movements.

Understanding of the normal function of the lateral pterygoid muscle is limited. The principal aim here was to determine whether there is a progressive increase in lateral pterygoid activity as the mandibular condyle moves downwards and forwards as would be expected if the muscle is concerned with the precise horizontal positioning of the mandible. In eight humans, recordings were made of the activity of the superior (SHLP) and inferior (IHLP) heads of the lateral pterygoid and the masseter, anterior temporal, posterior temporal and digastric muscles, together with the movement of the palpated lateral condylar pole (JAWS-3D tracking system) during trials of a contralateral and a protrusive jaw movement. Recording sites in SHLP and, in one participant, IHLP were verified by computed tomography. In each participant there was a progressive increase in the rectified and smoothed SHLP and IHLP activity in association with condylar movement during the contralateral and protrusive jaw movement. Further, irregularities in condylar movement, which reflected variations in the rate at which the jaw was moved, were correlated in time with prominent bursts of SHLP and IHLP activity. In all participants there was a consistently high correlation coefficient between the rectified and smoothed SHLP and IHLP activity and condylar displacement during the contralateral or protrusive jaw movements. For example, the mean (+/-SD) correlation between anterior condylar translation during contralateral excursion and SHLP activity was 0.91+/-0.09, and for IHLP 0.96+/-0.02. For the masseter, anterior temporal, posterior temporal and digastric muscles, mean r-values were, respectively, 0.10+/-0.77; -0.14+/-0.72; 0.24+/-0.78; 0.54+/-0.47. When treated as a group the correlation coefficients for SHLP and IHLP were statistically significantly different from the correlation coefficients for the other muscles treated as a group (ANOVA; p < 0.002 for correlation with anterior translation). These observations support the notion that the lateral pterygoid provides the principal driving force for moving the jaw forwards or laterally in protrusive or lateral excursive condylar movements. Further, the data suggest that the muscle plays a part in the fine control of jaw movements.

Adult↗
PubMed1986

Lateral diffusion of ganglioside GM1 in phospholipid bilayer membranes.

The lateral diffusion coefficient of ganglioside GM1 incorporated into preformed dimyristoylphosphatidylcholine (DMPC) vesicles has been investigated under a variety of conditions using the technique of fluorescence photobleaching recovery. For these studies the fluorescent probe 5-(((2-Carbohydrazino)methyl)thio)acetyl) amino eosin was covalently attached to the periodate-oxidized sialic acid residue of ganglioside GM1. This labeled ganglioside exhibited a behavior similar to that of the intact ganglioside, and was able to bind cholera toxin. The lateral diffusion coefficient of the ganglioside was dependent upon the gel-liquid crystalline transition of DMPC. Above Tm the lateral diffusion coefficient of the ganglioside was 4.7 X 10(-9) cm2 s-1 (with greater than 80% fluorescence recovery). This diffusion coefficient is significantly slower than the one previously observed for phospholipids in DMPC bilayers. The addition of increasing amounts of ganglioside, up to a maximum of 10 mol %, did not have a significant effect on the lateral diffusion coefficient or in the percent recovery. At 30 degrees C, the lateral mobility of ganglioside GM1 was not affected by the presence of 5 mM Ca2+, suggesting that, at least above Tm, Ca2+ does not induce a major perturbation in the lateral organization of the ganglioside molecules. The addition of stoichiometric amounts of cholera toxin to samples containing either 1 or 10 mol % ganglioside GM1 produced only a small decrease in the measured diffusion coefficient. The fluorescence recovery after photobleaching experiments were complemented with excimer formation experiments using pyrene-phosphatidylcholine. Above the transition temperature the presence of 10 mol % ganglioside GMI induced a large decrease in the rate of excimer formation. These results also indicated that the addition of ganglioside GMI to phospholipid bilayer vesicles induces a significant restriction in the lateral mobility parameters of the lipid bilayer and that the presence of Ca2' does not have a further effect in the mobility of the probe molecules.

Animals↗
PubMed1998

Membrane and circuit properties of lateral septum neurons: relationships with hippocampal rhythms.

The lateral septum receives the most important afferents from the hippocampus, has been proposed to contribute to theta (theta) rhythm generation. Our aim was to study the membrane and circuital properties of lateral septum neurons and their relationship with hippocampal rhythms. Extra- and intracellular recordings (n=81) were obtained in urethane-anesthetized rats. Two neuronal populations were found, one of them with hippocampal theta; rhythm dependence (theta-D, 68%), and the other group independent of hippocampal theta; rhythm (theta-I, 32%). Other differences were spontaneous firing rate (theta-D=13.20+/-2.09, theta-I=6.99+/-1.18; p<0.005) with a bursting pattern in the theta-D group and single discharges in the theta-I group. Intracellular recordings showed higher synaptic activity in theta-D than in theta-I neurons. Both groups showed fast spikes while only theta-D neurons had high-threshold and low-threshold slow spikes. theta-D neurons had theta-oscillations in their membrane potential. Stimulation of the contralateral lateral septum resets the hippocampal theta rhythm and the theta rhythm recorded intracellularly in the lateral septum neurons. Some neurons (10.6%) showed rhythmic oscillations lasting a few seconds, at a higher frequency than those of the simultaneously recorded hippocampal EEG. This high frequency appeared spontaneously or could be evoked by stimulations of the fornix and reticularis pontis oralis nucleus (RPO). Homologous high frequency oscillations appeared in the simultaneously recorded hippocampal EEG, synchronized with the neuronal activity, during fornix stimulation. RPO stimulation evoked increments (57%) or decrements (43%) in the firing rate of lateral septum neurons. Thus, they could participate in different septal networks to modulate the theta rhythm. The marked functional relationship between lateral septum neurons and hippocampal theta rhythm supports the proposal that lateral septum represents a feedback system for the improvement of medial septum theta rhythm. The hypothalamic projections could be a way to introduce theta and higher rhythms into this structure that control many biological rhythms.

Afferent Pathways↗