Dependence of the anterior olfactory area self-stimulation upon the lateral hypothalamic area

The functional relation between the anterior olfactory area (AO) and the lateral hypothalamic area (LH) was examined in a self-stimulation situation. Bar-pressing responses for AO sitmulation were suppressed by unilateral injection of procaine, and enhanced by glutamate, into LH. Neither procaine nor glutamate injected into AO had any influence upon LH self-stimulation. It is unlikely that the procaine effect was due to motor disturbance because similar injection of procaine into LH did not disturb the performance of a one-way avoidance task. It appears that the rewarding effect of AO stimulation is dependent upon the excitation of the more caudal structures including LH.     

Reflex pathways from group II muscle afferents

Summary A hypothesis is forwarded regarding the role of secondary spindle afferents and the FRA (flexor reflex afferents) in motor control. The hypothesis is based on evidence (cf. Lundberg et al. 1987a, b) summarized in 9 introductory paragraphs. Group II excitation. It is postulated that subsets of excitatory group II interneurones (transmitting disynaptic group II excitation to motoneurones) may be used by the brain to mediate motor commands. It is assumed that the brain selects subsets of interneurones with convergence of secondary afferents from muscles whose activity is required for the movement. During movements depending on coactivation of static -motoneurones impulses in secondary afferents may servo-control transmission to -motoneurones at an interneuronal level. The large group II unitary EPSPs in interneurones are taken to indicate that, given an adequate interneuronal excitability, impulses in single secondary afferents may fire the interneurone and produce EPSPs in motoneurones; interneuronal transmission would then be equivalent to that in a monosynaptic pathway but with impulses from different muscles combining into one line. It is postulated that impulses in the FRA are evoked by the active movements and that the role of the multisensory convergence from the FRA onto the group II interneurones is to provide the high background excitability which allows the secondary spindle afferents to operate as outlined above. The working hypothesis is put forward that a movement governed by the excitatory group II interneurones is initiated by descending activation of these interneurones, but is maintained in a later phase by the combined effect of FRA activity evoked by the movement and by spindle secondaries activated by descending activation of static -motoneurones. As in the original follow up length servo hypothesis (Rossi 1927; Merton 1953), we assume that a movement at least in a certain phase can be governed from the brain solely or mainly via static -motoneurones. However, our hypothesis implies that the excitatory group II reflex connexions have a strength which does not allow transmission to motoneurones at rest and that the increase in the gain of transmission during an active movement is supplied by the movement itself. Group II inhibition. It is suggested that the inhibitory reflex pathways like the excitatory ones have subsets of interneurones with limited group II convergence. When higher centres utilize a subset of excitatory group II interneurones to evoke a given movement, they may mobilize inhibitory subsets to inhibit muscles not required in the movement. Inhibition may be reciprocal of extensors during flexor activation (the spinal pattern), of flexors during extensor activation or of flexors and extensors in more complex movements involving cocontraction of other flexors and extensors. It is postulated that group II inhibition depends on conjoint activation from spindle afferents and other sources (descending and/or the FRA) so that inhibition may be coupled to group II excitation of other motoneurones. Such a coupling would correspond to the --linkage in reciprocal Ia inhibition (Lundberg 1970) and is denoted --linkage in lateral group II inhibition. FRA and other reflex pathways. Results are summarized showing that the FRA evoke convergent excitation in interneurones not only in group II reflex pathways but also in other reflex pathways like the reciprocal Ia inhibitory, the nonreciprocal group I inhibitory and probably also in specialized reflex pathways from cutaneous afferents. It is inferred that facilitation of reflex transmission by impulses in the FRA evoked by the active movement may be a general principle. In this way reflex transmission to -motoneurones may be weak at rest and not disturb passive movements but have a high gain when the reflexes are required to regulate active movement.This work was supported by the Swedish Medical Research Council (project no. 94)     

Development of brain stimulation reward in the medial prefrontal cortex: Facilitation by prior electrical stimulation of the sulcal prefrontal cortex

Electrical stimulation of the medial prefrontal cortex (MC) in rats delivered daily for seven days causes a marked improvement in the rate of acquisition of a self-stimulation response. In the present experiment, we looked at whether we could get the same facilitatory effect on self-stimulation of the MC by delivering pre-training stimulation to other points in the brain anatomically related to the MC. Electrical stimulation of the lateral hypothalamus was without effect. However, electrical stimulation of the sulcal prefrontal cortex (SC) either contralateral or ipsilateral to the MC electrode did facilitate acquisition of self-stimulation of the MC. Thus the SC and MC would appear to be part of the same substrate controlling the development of positive reinforcement in the MC.     

枢椎侧弓螺钉安全钉道的判定与测量

目的:利用Unigraphics(UG)三维重建技术寻找枢椎侧弓螺钉安全钉道的经过,并进行相关参数的测量.方法:对4例干燥和8例新鲜枢椎行CT扫描, UG软件重建虚拟实体,利用3.5 mm虚拟螺钉模拟进钉,寻找安全钉道经过的特征标记点.以此为基础,测定57例干燥枢椎安全钉道的内倾角与上倾角(AutoCAD环境)及进针点距峡部及下关节突外缘的距离(手工测量).结果:模拟发现横断面安全钉道经过前弓中宽后界的内中1/3交界与中宽前界的外中1/3交界,矢状面经过前弓中宽后界中部及前界中宽与上关节突下界交界处.对另57例干燥标本进行测量发现安全钉道的内倾角为左/右＝(10.94±6.53)°/(11.95±2.82)°,上倾角为(13.31±5.44)°/(14.45±3.80)°,在大多数标本椎板后下方有一突起的骨嵴 (左/右＝84.2%/84.98%) ,进针点多位于这一骨嵴线上(左/右＝87.5%/84.9%).进针点距离下关节外侧缘左/右＝(6.71±1.33)mm/(6.28±1.48)mm,距离后弓左/右＝(9.93±1.38)mm/(8.47±1.70)mm.个体间差异较大.结论:侧方椎弓螺钉固定的安全钉道在横断面经过横突孔区域(侧弓前份)中宽后界的内中1/3交界与中宽前界的外中1/3交界,矢状面经过后方中宽中部及前方中宽与关节突下界交界处,不同侧别间及不同个体间有明显差别.     

Effects of 9 -tetrahydrocannabinol and ethyl alcohol on adjunctive behavior and the lateral hypothalamus

The fact that electrical stimulation of the lateral hypothalamus (LH) can be substituted for the delivery of a food pellet in typical schedule induced polydipsia was established and demonstrated the role of this part of the brain in the mediation of adjunctive behavior. The assumption that Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and ethyl alcohol affect behavior because of a differential effect on the same LH mechanism was supported by the following evidence. Relatively small doses of Δ⁹-THC, 0.25, 0.375, and 0.50 mg/kg, enhanced adjunctive drinking; whereas, larger quantities of 0.625 and 0.75 mg/kg had no appreciable effects. The effect is somewhat specific, as it did not occur with strychnine sulfate, and rate dependent within limits as it was most pronounced in animals with low rates of responding or in animals when responding at a low rate. The effect of rate dependency was also apparent with fixed interval schedules of 2 and 4 min and a multiple schedule of a fixed interval and a signalled timed out period of nonreinforcement. Low rates of responding were enhanced by all doses of Δ⁹-THC, 1.0, 1.5, 2.0, 2,5, and 3.0 mg/kg, and there was an obvious dose related decrease in high rates. A similar effect was observed with low and high rates of electrical self-stimulation through implanted LH electrodes. The hypothesis that some drugs such as Δ⁹-THC and ethyl alcohol can enhance the positive feedback in an LH mediated motor control system by the facilitation of the same mechanism which initially generated the behavior was confirmed. Oral self administration of ethyl alcohol in a saccharin sweetened fluid enhanced recovered adjunctive drinking of the solution in quantities which should be sufficient to produce physical dependence if continued for relatively long periods. Recovered adjunctive drinking occurs in animals without food or water deprivation and it is an intense and persistent phenomenon.     

成人股骨骨髓腔影像解剖学及临床意义

目的 :为研制新型股骨髓内固定器提供解剖学依据。方法 :将 60支成人股骨干燥标本 ,拍摄标准的X线正侧位片 ,观察髓腔的形态 ,测量皮质骨的厚度 ,髓腔的横状径 ,矢状径 ,髓腔的轴线在不同节段与皮质骨内侧缘的切线形成的夹角等。结果 :正位片示髓腔呈“哑铃状” ,自上而下 ,横状径由大 (2 0 .0±0 .3 )mm变小 (11.1± 2 .4)mm ,再由小 (11.1± 2 .4)mm变最大 (3 2 .6± 5 .2 )mm。狭窄段横状径的直方图呈正态分布 ,均数为 (10 .7± 2 .0 )mm。侧位片示髓腔中上段的轴线与中下段的轴线所形成夹角为 (172 .2±2 .2 )° ,其夹角顶端距小转子下缘的实际长度为 (12 .8± 3 .0 )cm。结论 :①髓内钉不适合股骨中下段骨折的髓内固定。②组合式分叉防旋转的髓内钉适合股骨中下段的解剖学特点和力学要求。③顺行击钉 10～ 15cm处时 ,忌用暴力 ,减慢进入速度。     

Dopamine and serotonin: influences on male sexual behavior

Steroid hormones regulate sexual behavior primarily by slow, genomically mediated effects. These effects are realized, in part, by enhancing the processing of relevant sensory stimuli, altering the synthesis, release, and/or receptors for neurotransmitters in integrative areas, and increasing the responsiveness of appropriate motor outputs. Dopamine has facilitative effects on sexual motivation, copulatory proficiency, and genital reflexes. Dopamine in the nigrostriatal tract influences motor activity; in the mesolimbic tract it activates numerous motivated behaviors, including copulation; in the medial preoptic area (MPOA) it controls genital reflexes, copulatory patterns, and specifically sexual motivation. Testosterone increases nitric oxide synthase in the MPOA; nitric oxide increases basal and female-stimulated dopamine release, which in turn facilitates copulation and genital reflexes. Serotonin (5-HT) is primarily inhibitory, although stimulation of 5-HT(2C) receptors increases erections and inhibits ejaculation, whereas stimulation of 5-HT(1A) receptors has the opposite effects: facilitation of ejaculation and, in some circumstances, inhibition of erection. 5-HT is released in the anterior lateral hypothalamus at the time of ejaculation. Microinjections of selective serotonin reuptake inhibitors there delay the onset of copulation and delay ejaculation after copulation begins. One means for this inhibition is a decrease in dopamine release in the mesolimbic tract.     

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.