Influence of the superior colliculus on visual responses of cells in the rabbit's lateral posterior nucleus

Summary The lateral posterior-pulvinar (LP-P) complex of mammals receives a major input from the superior colliculus (SC). We have studied the response properties of LP cells and investigated the effects of reversible inactivation of the colliculus on the visual responses of LP units in anesthetized and paralyzed rabbits. Cells in LP had large receptive fields responsive to either stationary or moving stimuli. One third of the motion-sensitive cells were direction selective. The size of the receptive fields increased with eccentricity and there was a retinotopic organization along the dorso-ventral axis. Comparison of the LP and superior colliculus properties revealed substantial differences in visual response characteristics of these two structures such as the size of the receptive fields and the number of direction-selective cells. Electrical stimulation of the LP evoked antidromic action potentials in tectal cells that were motion sensitive. We found a dorsoventral gradient in the projections of collicular cells. Units located more dorsally in the colliculus sent their axons to LP while cells lying more ventrally sent axons toward the region lying posterior to LP. A micropipette filled with lidocaine hydrochloride was lowered into the superficial layers of the superior colliculus in order to reversibly inactivate a small population of collicular cells. Rendering the superior colliculus inactive produced a sharp attenuation of visual responses in the majority of LP cells. Some neurons ceased all stimulus-driven activity after collicular blockade while a few cells exhibited increased excitability following collicular inactivation. These experiments also indicate that the tecto-LP path is topographically organized. An injection in the colliculus failed to influence the thalamic response when it was not in retinotopic register with the LP cells being recorded. Our results demonstrate that the superior colliculus input to LP is mainly excitatory in nature.     

Phasic stimulation of the locus coeruleus: Effects on activity in the lateral geniculate nucleus

Neurons in the locus coeruleus (LC) encode information related to behavioral state in a tonic pattern of firing and information related to the occurrence of a sensory stimulus in a phasic pattern of firing. The effects of phasic stimulation of the LC (6 pulses at 30 Hz), designed to approximate its physiological activation by sensory stimuli, were studied in the lateral geniculate nucleus (LGN) of anesthetized rats. Phasic stimulation of the LC significantly increased neuronal firing in the LGN with a mean latency 320 ms from onset of stimulation. Receiver operating characteristic analyses on a trial-by-trial basis showed that phasic LC stimulation can result in a highly discriminable signal in the LGN. This increased neuronal firing rate in the LGN was specific for the site of stimulation and was reduced by the norepinephrine synthesis inhibitor αmethyl-p-tyrosine and by intravenous WB-4101 (α₁-receptor antagonist). Neurons in the LGN have a singlespike firing mode when sensory information is faithfully relayed from retina to cortex and a burst-firing mode when the transfer of this information is degraded. Phasic LC stimulation reduced burst firing (2–5 ms interspike intervals, ISIs) at low frequencies ( ≤4 Hz) in the LGN, and for some neurons there was an absolute decrease in burst-like ISIs after LC stimulation, despite an increase in mean firing rate.     

Principal cells of the rat medial nucleus of the trapezoid body: an intracellular in vivo study of their physiology and morphology

The medial nucleus of the trapezoid body (MNTB) is one of several principal nuclei in the superior olivary complex (SOC) of mammals. It is classically thought to function as a relay station between the contralateral ventral cochlear nucleus and the lateral superior olive (LSO), playing a role among those brainstem nuclei that are involved in binaural hearing. In order to characterise the physiology and morphology at the cellular level of the major neuronal component of the MNTB, the principal cells, we have analysed these neurons in rats in vivo using intracellular recordings and horseradish peroxidase-labelling. Our data demonstrate that MNTB principal cells, when being stimulated acoustically via the contralateral ear, show a phasic-tonic response with an onset latency of 3.5 ms and a suppression of their spontaneous activity following stimulus offset. These neurons have an axonal morphology whose complexity has not yet been described. All cells (n=10) projected exclusively ipsilaterally and had terminal axonal arbors in a variety of auditory brainstem nuclei. At least two and maximally seven auditory targets were innervated by an individual cell. Each cell projected into the LSO and the superior paraolivary nucleus (SPN). Additional projections that were intrinsic to the SOC were often observed in the lateral nucleus of the trapezoid body and in periolivary regions, with only one cell projecting into the medial superior olive. Most, if not all, MNTB principal cells also had projections that were extrinsic to the SOC, as their axons ascended into the lateral lemniscus. In two neurons the ascending axon formed terminal arbors in the ventral nucleus of the lateral lemniscus, and the dorsal nucleus of the lateral lemniscus could be identified as a target of one neuron. The location of the cell bodies of the MNTB principal cells correlated with the neurons' best frequencies, thereby demonstrating a tonotopic organisation of the MNTB, with high frequencies being represented medially and low frequencies laterally. The axonal projections into the LSO and the SPN were also tonotopically organised and the alignment of the tonotopic axes was similar to that in the MNTB. Our results confirm previous data from other species and suggest that MNTB principal cells have a great amount of physiological and morphological similarities across mammalian species. Furthermore, the complexity of the axonal projections indicates that these neurons play a role in auditory information processing which goes far beyond their previously described classical role.     

Lateral actions at the inner plexiform layer of the carp retina: effects of turning windmill pattern stimulus

Lateral action from amacrine to ganglion cells was studied in the isolated carp retina by using a truncated windmill pattern (TWP). About 25% of ganglion cells of both "on" and "off" center types were suppressed or enhanced in firing activity in response to TWP turning. The suppressed cells were more sensitive to slow turning velocities of TWP than the enhanced cells. In the "on-off" type amacrine cells, a steady depolarizing or hyperpolarizing component (less than several mV) was maintained by stationary TWP, while the cells were exclusively depolarized by turning TWP at a wide range of velocities. These results suggest that individual responses of ganglion cells induced by both stationary and turning TWP are depending on a balance between two factors: the polarizing direction of steady components of the "on-off" amacrine cells and the polarizing direction of ganglion cells synaptically produced by the amacrine cells.     

CCK and other peptides modulate hypothalamic norepinephrine release in the rat: Dependence on hunger or satiety

The purpose of this investigation was to determine the functional relationship between putative satiety peptides and endogenous norepinephrine (NE) activity in the hypothalamus. Permanent guide cannulae for push-pull perfusion were implanted stereotaxically in Sprague-Dawley rats so as to rest above the medial or lateral hypothalamus (LH). Post-operatively, the animals were either satiated with food and water, both available ad lib, or fasted for 18-22 hr prior to an experiment. To perfuse a site in the LH, paraventricular (PVN) or ventromedial nucleus (VMN), a concentric 29-23 ga push-pull cannula system was lowered to a pre-determined site, in most cases after catecholamine stores had been pre-labeled with [3H]-NE. During control tests, an artificial CSF was perfused at a rate of 20-25 microliter/min for 5-8 min with a 5 min interval between each sample. The addition of cholecystokinin (CCK) in a concentration of 2.0-6.0 ng/microliter to the CSF perfused in PVN or VMN of the satiated rat enhanced the efflux of NE; however, in the fasted animal CCK often suppressed the catecholamine's release. Perfused in the LH, CCK exerted opposite effects, typically augmenting NE output when the rat was fasted but not affecting the amine's activity during the sated condition. Proglumide (1.2 micrograms/microliter) attenuated CCK's effect in releasing NE when the antagonist was perfused in the PVN of the satiated rat. Similar experiments in which neurotensin (NT) was perfused in the LH, PVN and VMN revealed virtually the same inverse effects on NE release in the fasted and satiated rat, which again were anatomically specific. Finally, insulin and 2-deoxy-D-glucose (2-DG) exerted similar state-dependent effects on the release of NE within LH and PVN. Overall, the results suggest that CCK or other neuroactive peptide could serve as a "neuromodulator" of the pre-synaptic release of NE within classical hypothalamic structures which are thought to underlie both hunger and satiety. The state-dependent nature of the peptides' activity on the noradrenergic feeding mechanism implies that these substances constitute a pivotal portion of the profile of factors which impinge functionally upon the hypothalamic neurons responsible for the feeding response and its cessation.     

Long-term effects of lateral hypothalamic lesions on brown adipose tissue in rats

A classic feature of animals with lateral hypothalamic (LH) lesions is their regulation of body weight at sub-normal levels. The present studies were done to determine whether this is associated with enhanced thermogenic activity of their brown adipose tissue (BAT). Three groups of young chow-fed male Holtzman rats were formed: (1) animals receiving bilateral radiofrequency heat lesions of the dorsal LH and then permitted free access to chow (LH rats); (2) non-lesioned animals that were pair-fed (PF) to the lesioned rats during a 2 week post-operative recovery period (Phase 1); (3) non-lesioned, ad lib fed (NORM) controls. After Phase 1, each group was divided and permitted free access to chow alone or an additional selection of palatable, novel food items (a "cafeteria" diet) for 2-3 weeks (Phase 2) to stimulate diet-induced thermogenesis in BAT. Finally, half of each sub-group was exposed to 4 degrees C for 15 hr to stimulate nonshivering thermogenesis in BAT. During Phase 1 LHs and PFs ate 50% less than NORMs. This resulted in a weight deficit of 16% for LHs and 12% for PFs. After the additional period of feeding palatable foods (Phase 2) LHs collectively weighed 14% less than NORMs whereas previously PFs had a weight deficit of only 4%. They gained less weight than NORMs or PFs despite a similar energy intake. LHs had small deposits of gonadal white adipose tissue [both total amount and expressed per metabolic body mass (kg 0.75)]. The weight of interscapular BAT was less in the LHs but its concentration of protein (mg/g) was higher.(ABSTRACT TRUNCATED AT 250 WORDS)     

旋髂深动脉及其临近结构的观测

目的：研究旋髂深动脉与临近结构的位置关系,为临床应用提供解剖学依据。方法：应用成年尸体20具（40侧,男尸12具,女尸8具）,观察旋髂深动脉,髂腹下神经,髂腹股沟神经,股外侧皮神经及它们之间的位置关系,结果：旋髂深动脉与神经之间有密切的毗邻关系,结论：临床上在作髂骨瓣移植分离切断旋髂深动脉及其分支时,应注意保护有关的神经。     

The Patient-Rated Tennis Elbow Evaluation Questionnaire was successfully translated to Persian

IntroductionThe Patient-Rated Tennis Elbow Evaluation (PRTEE) is designed to evaluate pain and disability in subjects with lateral elbow tendinopathy. This questionnaire is available in Swedish, Italian, and some other languages. A Persian language version of the questionnaire is needed for both research and clinical purposes.Purpose of the StudyThe purpose of this study was to translate and cross-culturally adapt the PRTEE questionnaire into the Persian language and to determine its validity and reliability.MethodsThe PRTEE was translated and culturally adapted from English into Persian (PRTEE-P) according to the established guidelines. The PRTEE-P was completed by 68 Iranian subjects (44 women, 24 men) diagnosed with chronic lateral elbow tendinopathy. To assess test-retest reliability, all subjects filled out the PRTEE-P on a second admission within one week. The intraclass correlation coefficient (ICC) and Cronbach's alpha were measured to report reliability. The validity was determined by correlating the PRTEE-P questionnaire with the Persian version of the Disabilities of the Arm, Shoulder, and Hand questionnaire.ResultsThe Persian version of the PRTEE showed a high internal consistency with a Cronbach's alpha of 0.99, demonstrating good test-retest reliability (ICC = 0.99). It was well correlated with Disabilities of the Arm, Shoulder, and Hand (r = 0.80).ConclusionThe PRTEE-P is a reliable and valid tool designed for measuring pain and disability in subjects with lateral elbow tendinopathy.     

Role of strengthening during nonoperative treatment of lateral epicondyle tendinopathy

IntroductionLateral epicondyle tendinopathy (LET) is the most common cause of lateral elbow pain. The literature on rehabilitation of the condition encompasses a plethora of interventions with most current evidence indicating that stretches and some form of strengthening are vital components. However, patient outcomes are infrequently reported further than 12 weeks from the start of therapy and it is unclear which components of a home exercise program are necessary to alleviate symptoms up to one year from the initiation of a therapy program.Purpose of the StudyThe purpose of the study is to determine if a therapy program with 4 to 6 visits spaced out over 12 weeks focusing on self-management and strengthening is more effective in reducing pain and improving function long term than the same program without strengthening, for individuals with LET.Study DesignThis is a randomized controlled trial.MethodsNinety-four patients were randomly allocated into two groups: both groups received the interventions of education in pertinent pathoanatomy, stretching, pain management through rest and icing, and activity modification. Group 1 (n = 38) was also provided with a strengthening component to the home exercise program, whereas group 2 did not (n = 21). Our primary outcome measure was pain at rest and pain with activity; our secondary measure was the level of functional impairment as measured by the quick disabilities of arm shoulder and hand. Outcome measurements were assessed at baseline, 6, 12, 24, and 52 weeks after initiation of therapy.ResultsBoth groups demonstrated statistically significant improvement with a moderate to large effect size in pain and function scores when compared with previous time point at 6, 12, and 24 weeks. Pain continued to decrease for both groups from 24 weeks to 52 weeks, but interestingly, there was a significant increase with moderate effect size in the quick disabilities of arm shoulder and hand score at 52 weeks when compared with week 24. No statistically significant difference was found between the two groups at any time point up to 52 weeks from the start of therapy.ConclusionsThis study demonstrates that a therapy program consisting of a low number of visits spaced out over 12 weeks based on education, stretches, activity modification, and pain management techniques is effective at reducing pain and increasing function in patients with LET. The addition of strengthening to this program did not improve outcomes. The therapy approach used in this study is consistent with the International Classification of Function guidelines and focuses on engaging patients in self-management of the condition through patient education and self-empowerment.