Reduced Febrile Responses to Peripheral and Central Administration of Pyrogen in Aged Squirrel Monkeys

There is long-standing controversy as to whether fever capacity is reduced in aged man. Although loss of this cardinal sign of disease would be an impediment to diagnosis and treatment, there has been no previous research on altered febrile responses using aged primate models. In the present experiments the febrile reaction to IV Salmonella typhosa endotoxin was reduced in monkeys over 14 years old and in one-third of those 10–14 years of age compared with that of younger animals. In response to injections of endotoxin into the lateral cerebral ventricle (ICV), animals over 10 years old showed small or no fevers. Injections of probenecid (ICV), an inhibitor of central inactivation of leukocytic pyrogen and prostaglandin, augmented fever caused by IV and ICV endotoxin and hyperthermia caused by ICV PGE₂ in animals under 10 years of age. However, in older animals probenecid increased fever caused by ICV endotoxin only, although the increased response was still less than one quarter that of younger animals. The results indicate that old squirrel monkeys have decreased febrile responses that may be traced to alterations in central sensitivity to pyrogens.     

Responses to acoustic stimuli of units in the auditory cortex of awake squirrel monkeys

Summary The responses of single units in the superior temporal gyrus of awake squirrel monkeys to tone pips, noise, clicks, and frequency-modulated sounds were recorded with extracellular microelectrodes. A majority of the units responded to acoustic stimulation, pure tone pips being the most effective in terms of the percentage of units responding (71%). No simple catalogue of response types could be elicited. Units varied in terms of the combinations of stimuli to which they were responsive, the frequency range over which pure tones were effective, and the temporal pattern of discharge to different frequencies and different types of stimuli. A substantial majority of units gave precise timed responses to the onset or offset of the stimuli, while a few introduced long delays between the stimulus and the response. With regard to the area studied, acoustic units could be found between stereotaxic coordinates A3 and A10, both on the lateral surface of the hemisphere and in the superior temporal plane, as well as in the caudal insular region. No precise tonotopic organization could be discerned.Peter Winter died in a skiing accident in March, 1972.     

黄连注射液对家兔白细胞致热原性发热和脑脊液中cAMP含量变化的影响

本研究用兔78只,分两部分进行实验。第一部分,观察黄连注射液对家兔白细胞致热原(1eucocytic pyrogen;LP)性发热的降热效应;39只兔分成四组;Ⅰ为LP组;Ⅱ为黄连 LP组;Ⅲ为黄连组,Ⅳ为对照组。Ⅰ组9只兔,Ⅱ～Ⅳ组各10只兔。第二部分,观察黄连注射液对发热家兔脑脊液中cAMP含量变化的影响。动物数与分组同第一部分。结果表明,LP 黄连组60分钟△T℃(0.70±0.12),TRI_4(3.37±0.07)明显低于LP组△T℃(1.11 0.11)、TRI_4(5.56±0.10),分别比较两组△T℃、TRI_4,其差异性均非常显著(P<0.01)。上述两组动物60分钟脑脊液中cAMP含量分别为0.76±0.08和1.29±0.13,统计学处理后差异性非常显著(P<0.01)。黄连组动物60分钟△T℃(0.04±0.10)与对照组△T℃(0.03±0.06)相比较,无统计学意义(P>0.05)。作者推论:黄连注射液降热作用的机制,很可能与抑制POAH区神经元cAMP的生成有关。     

电针家兔“百会穴”对内生致热原性发热和脑脊液cAMP含量的影响

为了探讨cAMP在电针发热家兔“百会穴”降热效应中的作用,作者选用封闭群大耳白家兔108只,分五组进行实验。实验结果表明:(一)电针发热家兔“百会穴”后,明显降低发热反应和脑脊液cAMP含量增加;(二)电针封闭发热家兔“百会穴”和发热家免“非穴位”后,显示明显的发热反应和脑脊液cAMP含量显著增加;(三)单纯封闭发热家兔“百会穴”,对发热反应和脑脊液cAMP含量增加均无影响。因此,作者推论:电针发热家免“百会穴”抑制发热效应的机理,很可能是和电针“百会穴”中的局部敏感组织(如游离神经末梢)所感受,通过某种方式传入脑内,在脑内又以某种方式抑制cAMP的增多有关,从而抑制调定点上移和出现发热抑制效应。     

柴胡注射液对家兔内生致热原性发热及其脑脊液cAMP含量变化的效应

本实验共分二部分进行。第一部分,观察柴胡注射液解热效应,第二部分,观察柴胡注射液解热时对脑脊液cAMP含量变化的影响。用家兔内生致热原复制发热模型,剂量(1×10~6 cells/ml)0.5ml/kg。目前认为:cAMP是一种重要的中枢性发热介质,脑脊液中cAMP含量与发热效应呈正相关。本研究结果表明,柴胡注射液(250mg/kg)对内生致热原性发热有明显抑制作用;同时,脑脊液中cAMP含量也明显低于发热对照组。作者推论:柴胡注射液可能通过某些环节减少体温调节中枢神经元cAMP合成和释放,从而抑制发热效应。     

柴葛解肌汤对家兔白细胞致热原性发热效应及脑脊液cAMP含量的影响

本研究选用65只新西兰白兔,观察经口灌入柴葛解肌汤(柴葛汤)对家兔白细胞致热原(LP)性发热效应及脑脊液cAMP含量的影响。结果表明:(1)柴葛汤经口灌入对家兔正常体温没有明显影响(P>0.05)。(2)单独静脉注射LP组,体温上升0.93±0.07℃,静注LP前1小时经灌口注柴葛汤,体温上升仅0.29±0.07℃,两组均数比较有非常显著的差异(p<0.01),说明柴葛汤具有明显的解热作用。(3)静注LP 1小时(LP性发热高峰期),脑脊液cAMP含量为141.18±23.04pmol/ml,静注LP前1小时经口灌入柴葛汤,脑脊液cAMP含量为94.37±6.20pmol/ml,两者比较有显著差异(P<0.05)。相关检验表明,柴葛汤 LP组的体温上升高度与脑脊液cAMP含量变化呈明显正相关。表明柴葛汤不仅抑制LP引起的发热反应,而且明显低降LP引起的脑脊液cAMP含量增多。根据这些实验绪果,作者推论,柴葛汤可能是通过降低脑内上升的cAMP含量而导致解热效应的。     

Memory Deficits in Aged Cebus Monkeys and Facilitation With Central Cholinomimetics

Cebus monkeys of 3 different age groups were trained to perform an automated behavioral task (delayed response), intended to measure recent memory ability. In in initial study, the aged monkeys (18 years and older) exhibit prprogressively greater performance impairments (relative to young monkeys) as they were required to remember the location of a visual stimulus for increasingly longer durations (0 to 20 sec). This deficits replicated previously published results from aged Rhesus monkeys and appeared similar to the primary memory deficits reported in elderly humans and demented patients. In subsequent studies, the effects of three different cholinomimetics were evaluated for their ability to improve the aged monkey's performance on this task. Each monkey was tested under several acute doses of the cholinergic precursor, choline, the anticholinesterase, physostigmine, and the cholinergic muscarinic receptor agonist, arecoline. The results revealed clear differences in the ability of these drugs to improve performance on this task. Choline exerted no apparent effects in the aged monkeys at any dose tested. Physostigmine clearly enhanced performance in certain aged monkeys, but the optimal dose varied dramatically between subjects, replicating previously published results with aged Rhesus monkeys and humans. Arecoline produced clear improvement within a restricted dose range, with little variation in optimal dose between subjects. In addition to demonstrating differences in the effects of different cholinomimetics on memory performance in aged primates, these data also suggest a possible rationale for future investigations. Assuming that each of these drugs primarily affected cholinergic function in the manner conventionally attributed, these data suggest that, within the cholinergic system, the more directly one stimulates the receptor, the more one might expect robust and consistent effects on memory performance in aged subjects.     

Memory Deficits in Aged Cebus Monkeys and Facilitation With Central Cholinomimetics

Cebus monkeys of 3 different age groups were trained to perform an automated behavioral task (delayed response), intended to measure recent memory ability. In in initial study, the aged monkeys (18 years and older) exhibit prprogressively greater performance impairments (relative to young monkeys) as they were required to remember the location of a visual stimulus for increasingly longer durations (0 to 20 sec). This deficits replicated previously published results from aged Rhesus monkeys and appeared similar to the primary memory deficits reported in elderly humans and demented patients. In subsequent studies, the effects of three different cholinomimetics were evaluated for their ability to improve the aged monkey's performance on this task. Each monkey was tested under several acute doses of the cholinergic precursor, choline, the anticholinesterase, physostigmine, and the cholinergic muscarinic receptor agonist, arecoline. The results revealed clear differences in the ability of these drugs to improve performance on this task. Choline exerted no apparent effects in the aged monkeys at any dose tested. Physostigmine clearly enhanced performance in certain aged monkeys, but the optimal dose varied dramatically between subjects, replicating previously published results with aged Rhesus monkeys and humans. Arecoline produced clear improvement within a restricted dose range, with little variation in optimal dose between subjects. In addition to demonstrating differences in the effects of different cholinomimetics on memory performance in aged primates, these data also suggest a possible rationale for future investigations. Assuming that each of these drugs primarily affected cholinergic function in the manner conventionally attributed, these data suggest that, within the cholinergic system, the more directly one stimulates the receptor, the more one might expect robust and consistent effects on memory performance in aged subjects.     

家兔内毒素双相热各期脑脊液和血浆cAMP含量的观察

本研究用静脉注射内毒素复制家兔双相热模型,观察双相热各期颈动脉血浆和脑脊液cAMP含量的变化及其与体温变化的关系,结果如下:1.内毒素非热限剂量一次静脉注射引起典型双相热。脑脊液cAMP含量在两个热相高峰期相应出现两个上升波,间歇期体温下降时,脑脊液cAMP含量相应降低,退热后恢复正常。血浆cAMP含量仅在第一热相增高。2.相关检验表明,脑脊液cAMP含量与体温变化呈显著正相关。血浆cAMP含量仅在第一热相与脑脊液cAMP含量相关。以上结果与内生致热原双相热相似,提示内毒素可能主要通过内生致热原以某种方式影响体温调节中枢cAMP的变化,导致双相热型的出现     

Response of mother and infant squirrel monkeys to separation and disturbance

Plasma cortisol values were obtained from squirrel monkey mothers and infants after two types of brief separation: infant removed to a nearby cage and infant removed to a different room. Cortisol values were also obtained during basal conditions, and after 30 min exposure to an unfamiliar juvenile conspecific when mothers and infants were allowed to maintain contact. For either separation condition, both mothers and infants exhibited significant cortisol elevations, and overall, infants ‘corticoid values were much greater than mothers’. Behavioral measures were also obtained from mothers, who during both separations tended to show marked behavioral agitation. The partner's presence or absence during separation did not produce differential behavioral or corticoid responses by either mother or infant. However, the presence of the unfamiliar conspecific induced clearly significant cortisol elevations in the infant but only slight elevations in the mother.     

大鼠内生致热原性发热时不同脑区精氨酸加压素和亮氨酸脑咖啡肽含量的变化

本实验用大鼠静脉注射内生致热原（ＥＰ）复制发热模型。观察发热反应及发热不同时相、不同胞区精氨酸加压素（ＡＶＰ）和亮氨酸脑啡肽（Ｌ－ＥＫ）含量的变化。结果表明：大鼠ＥＰ双相热时下丘脑组织ＡＶＰ含量在双峰热的两个高峰期和体温恢复期均明显高于对照组，ＡＶＰ含量与发热第一时相和第二时相体温升高有相关关系。而脑干和大脑皮质组织中ＡＶＰ含量则无明显变化。下丘脑组织、脑干组织中Ｌ－ＥＫ含量在双峰热的两个高峰期均高于对照组，恢复期脑干组织中Ｌ－ＥＫ含量仍高于对照组。大脑皮质组织中Ｌ－ＥＫ含量无明显变化。提示ＥＰ性发热时中枢的ＡＶＰ和Ｌ－ＥＫ可能参与体温调节反应。     

Effect of ablation of area postrema on frequency and latency of motion sickness-induced emesis in the squirrel monkey

Twelve young adult squirrel monkeys of the Bolivian subspecies were subjected to continuous counter-clockwise horizontal rotary motion at 25 rpm, together with a simusoidal vertical excursion of 6 in. every 2 sec (0.5 Hz). Each animal was exposed to this motion regimen for a period of 60 min once each week for three consecutive weeks. Following the third weekly motion test bilateral ablation of the area postrema (AP) was performed in eight of the animals by thermal cautery. Two control animals were sham-operated after the third motion test while two additional controls were given the motion tests as noted above but were not operated. The four controls were considered as a single group for statistical analyses of results of the motion tests. After a recovery period of 30 to 40 days, and at a comparable interval in the non-operated controls, each animal was again tested for motion sensitivity for three consecutive weeks. The brains of all of the animals were then fixed by left ventricular cardiac perfusion with Bouin's fluid and processed for histological evaluation of the bilateral AP ablation in comparison with the control brains. Five of the AP-ablated animals postoperatively were completely refractory to the motion stimuli, two exhibited a decreased number of emetic responses, and one exhibited the same number of responses before and after the AP lesions. The controls exhibited no significant difference in emetic sensitivity on the second series of three weekly tests than on the first series. The results of this investigation appear to be in agreement with the observations of Wang and Chinn in the dog [32,33] indicating that the intergrity of the AP (CTZ) is essential to the emetic response to motion.     

Peripheral Muscle Targets and Central Projections of the Mesencephalic Trigeminal Nucleus in Macaque Monkeys

The mesencephalic trigeminal nucleus (MesV) contains the somata of primary afferent neurons that innervate muscle spindles in masticatory muscles and mechanoreceptors in the periodontal ligaments. There are conflicting reports about additional peripheral targets of MesV, such as the extraocular muscles, as well as about its central targets. In addition, only limited primate data are available. Consequently, we examined MesV projections in macaque monkeys. The retrograde tracer wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) was injected into masticatory or extraocular muscles to define the peripheral targets of the primate MesV. Numerous labeled neurons were found in ipsilateral MesV after masticatory muscle injections. The scattered distribution of labeled cells, and their presence among clusters of unlabeled cells, suggests the muscle representations overlap. Just a few MesV neurons were labeled after extraocular muscle injections. This correlates with the small number of muscle spindles present in macaque extraocular muscles, suggesting MesV cells supplying extraocular muscle spindles may contribute a minor component to oculomotor proprioception. To examine the central connections of MesV, biotinylated dextran amine (BDA) was injected into the spinal trigeminal nucleus (Vs). The presence of retrogradely labeled MesV cells indicated a projection to Vs from MesV. These injections also anterogradely labeled terminals that lay in close association with MesV cells, suggesting an ascending projection from Vs to MesV. Finally, a small number of MesV neurons were labeled after WGA‐HRP injections into the upper cervical spinal cord. This pattern of central connections indicates MesV and Vs information is combined to guide mastication. Anat Rec, 291:974–987, 2008. © 2008 Wiley‐Liss, Inc.     

Contributions of regularly and irregularly discharging vestibular-nerve inputs to the discharge of central vestibular neurons in the alert squirrel monkey

 The discharge of neurons in the vestibular nuclei was recorded in alert squirrel monkeys while they were being sinusoidally rotated at 2 Hz. Type I position-vestibular-pause (PVP I) and vestibular-only (V I) neurons, as well as a smaller number of other type I and type II eye-plus-vestibular neurons were studied. Many of the neurons were monosynaptically related to the ipsilateral vestibular nerve. Eye-position and vestibular components of the rotation response were separated by multiple regression. Anodal currents, simultaneously delivered to both ears, were used to eliminate the head-rotation signals of irregularly discharging (I) vestibular-nerve afferents, presumably without affecting the corresponding signals of regularly discharging (R) afferents. R and I inputs to individual central neurons were determined by comparing rotation responses with and without the anodal currents. The bilateral currents, while reducing the background discharge of all types of neurons, did not affect the mean vestibular gain or phase calculated from a population of PVP I neurons or from a mixed population consisting of all type I units. From this result, it is concluded that I inputs are canceled at the level of secondary neurons. The cancellation may explain why the ablating currents do not affect the gain and phase of the vestibulo-ocular reflex. While cancellation was nearly perfect on a population basis, it was less so in individual neurons. For some neurons, the ablating currents decreased vestibular gain, while for other neurons the vestibular gain was increased. The former neurons are interpreted as receiving a net excitatory (I-EXC) I input, the latter neurons, a net inhibitory (I-INH) input. When compared with the corresponding R inputs, the I inputs were usually small and phase advanced. Phase advances were larger for I-EXC than for I-INH inputs. The sign and magnitude of the I inputs were unrelated to other discharge properties of individual neurons, including discharge regularity and the phase of vestibular responses measured in the absence of the ablating currents. Unilateral currents were used to assess the efficacy of ipsilateral and contralateral pathways. Ipsilateral pathways were responsible for almost all of the effects seen with bilateral currents. The results suggest that the vestibular signals carried by central neurons, even by those neurons receiving a monosynaptic vestibular-nerve input, are modified by polysynaptic pathways. Received: 22 July 1996 / Accepted: 25 October 1996     

Histochemical mapping of succinic dehydrogenase and cytochrome oxidase in the spinal cord, medulla oblongata and cerebellum of squirrel monkey (Saimiri sciureus)

Summary The distribution of succinic dehydrogenase (SDA) and cytochrome oxidase (Cy. O) in serial sections of the cervical region of the spinal cord and the medulla oblongata, arranged caudo-cranially, has been described. The motor cranial nerve nuclei exhibit strong SDA and Cy. O activity in the neurons and neuropil. The nuclei gracilis, cuneatus, olivaris inferior, cochlearis and vestibularis likewise show strong enzyme activity. Nucleus intercalatus and nucleus tractus solitarius, however, show weak and moderate enzyme activity respectively. The lateral part of formatio reticularis myelencephali shows less SDA and Cy. O compared to the medial part, which shows some accumulation of these enzymes in the neuropil.The neuropil of the molecular layer of cerebellar cortex and the perikarya and dendrites of the Purkinje cells show strong SDA and Cy. O activity. The granular layer exhibits stronger SDA and Cy. O in the synaptic glomeruli. The cerebellar nuclei possess stronger enzyme activity in the neurons and dendritic branches, compared to mild activity in the neuropil.Abbreviations AB Nucleus ambiguus - AP Area postrema - Cb Cerebellum - Cn Nucleus cuneatus medialis - CnL Nucleus euneatus lateralis - CRF Corpus restiforme - D Cell group D of meesen and Olszewski (1949) - DPy Decussatio pyramidum - DV Nucleus dorsalis n. vagi - F Cell group P of Meesen and Olszewski (1949) - FC Puniculus cuneatus - FG Funiculus gracilis - FLM Fasciculus longitudinalis medialis - FRM Formatio reticularis myelencephali - G Nucleus gracilis - Gr Granular layer of cerebellar cortex - I Nucleus intercalatus - Lcb Lingula cerebelli - MoL Molecular layer of cerebellar cortex - NC Nucleus cochlearis - NCD Nucleus cochlearis dorsalis - NCV Nucleus cochlearis ventralis - ND Nucleus dentatus - NE Nucleus emboliformis - NF Nucleus fastigii - NFL Nerve fiber layer - NG Nucleus globosus - NR Nucleus raphes - NSV Nucleus tractus spinalis n. trigemini - NTS Nucleus tractus solitarius - NVI Nucleus n. abducentis - NVII Nucleus n. facialis - NXII Nucleus n. hypoglossi - OI Nucleus olivaris inferior - OIm Nucleus olivaris inferior, accessorius medialis - OIp Nucleus olivaris inferior, principalis - P Layer of Purkinje cells - Pp Nucleus praepositus - Py Tractus pyramidalis - RG Nucleus reticularis gigantocellularis - RL Nucleus reticularis lateralis myelencephali - RPM Nucleus reticularis paramedianus myelencephali - SGD Nucleus substantiae griseae dorsalis - SGL Nucleus substantiae griseae lateralis - SGV Nucleus substantiae griseae ventralis - TCV Tractus corticospinalis ventralis - TS Tractus solitarius - TSC Tractus spinocerebellaris - VI Nucleus vestibularis inferior - VL Nucleus vestibularis lateralis - VM Nucleus vestibularis medialis - VS Nucleus vestibularis superior - IV Ventriculus quartus     

Entrainment and masking of circadian drinking rhythms in primates: Influence of light intensity

The entrained drinking rhythms of squirrel monkeys were studied during exposure to 24 hr illumination cycles of three different intensities (60:0; 66:6; 76:16 lux). Increasing the intensity of ambient illumination significantly delayed the offset of drinking but had no effect on either the onset or the total amount of daily drinking behavior. Comparison of drinking behavior under an alternating schedule of LD 66:6 lux and constant light of 6 lux indicated that the twice daily light transitions consistently altered the temporal distribution of drinking behavior. The daily timing of squirrel monkey drinking behavior thus, depends not only on the mechanisms of circadian entrainment to the LD cycle, but also on the ability of the LD cycle to directly influence, or “mask” behavior.     

Histochemical mapping of succinic dehydrogenase and cytochrome oxidase in the pons and mesencephalon of squirrel monkey (Saimiri sciureus)

Summary The distribution of succinic dehydrogenase (SDA) and cytochrome oxidase (Cy. O) has been investigated in a series of sections through the pons and mesencephalon of the squirrel monkey brain. The localization of the two enzymes is very similar in the various regions and shows only slight differences. The epiphysis, however, shows moderately strong SDA and very mild Cy. O activity. Particularly strong SDA and Cy. O activity has been observed in the cell bodies of the various cranial nerve nuclei, nucleus colliculi inferioris, colliculi superioris, nuclei griseum pontis, reticularis tegmenti pontis, lemnisci lateralis pars dorsalis, geniculatum laterale and mediale, and pulvinaris. The enzyme content of the neurons and cell bodies is generally stronger compared to the neuropil which often occurs in smooth, loose, compact and reticulated forms. Any special relationship between the neurons and neuropil with regard to their enzyme content has, however, not been observed. The cranial nerves, and fibers of the brachium conjunctivum, corpus callosum, and fornix show very mild enzyme activity except those of the trapezoid complex which show moderate enzyme activity.Abbreviations Ann Nucleus annularis - APT Area praetectalis - AS Aquaeductus Sylvii - BC Brachium conjunctivum - BCI Brachium colliculi inferioris - BCS Brachium colliouli superioris - BP Brachium pontis - Cb Cerebellum - CC Corpus callosum - CCI Commissura colliculi inferioris - CCS Commissura colliculi superioris - Cd Nucleus caudatus - CHD Commissura hippocampi —parsdorsalis - CoI Colliculus inferior - CoP Commissura posterior - CoR Corona radiata - CoS Colliculus superior - CPf Cortex piriformis - CR Cortex retrosplenialis - DBC Decussatio brachii conjunctivi - DG Nucleus dorsalis tegmentalis(Gudden) - DR Nucleus dorsalis raphes - EP Epiphysis - F Fornix - FH Fimbria hippocampi - FLM Fasciculus longitudinalis medialis - FRPC Formatio reticularis pontis, parscaudalis - FRPO Formatio reticularis pontis, parsoralis - FRTM Formatio reticularis tegmentimesencephali - GC Substantia grisea centralis - GCd Substantia grisea centralis, parsdorsalis - GCv Substantia grisea centralis, parsventralis - GL Corpus geniculatum laterale - GM Corpus geniculatum mediate - GPO Griseum pontis - Hipp Hippocampus - HL Nucleus habenulae lateralis - HM Nucleus habenulae medialis - IP Nucleus interpeduncularis - LC Nucleus locus coeruleus - LCb Lingula cerebelli - Lim Nucleus limitans thalami - LL Lemniscus lateralis - LLD Nucleus lemnisci lateralis —parsdorsalis - LM Lemniscus medialis - LP Nucleus lateralis posterior thalami - MD Nucleus medialis dorsalis thalami - Mv Nucleus motorius n. trigemini - NCI Nucleus colliculi inferioris - NCS Nucleus centralis superior tegmenti - NCT Nucleus trapezoideum - NMv Nucleus tractus mesencephalicus n.trigemini - NR Nucleus ruber - NST Nucleus supratrochlearis - NSv Nucleus tractus spinalis n. trigemini - NiiiC Nucleus centralis n. oculomotorii - NiiiD Nucleus n. oculomotorii — pars dor-salis - NiiiV Nucleus n. oculomotorii — pars ven-tralis - Niv Nucleus n. troehlearis - nvm Nervus trigeminus, portio major - niv Nervus trochlearis - nvi Nervus abducens - OS Nucleus olivaris superior - P Nucleus posterior thalami - PbL Nucleus parabrachialis lateralis - PbM Nucleus parabrachialis medialis - PC Pedunculus cerebri - Pg Nucleus parabigeminalis - PUI Nucleus pulvinaris inferior thalami - PUL Nucleus pulvinaris lateralis thalami - PUM Nucleus pulvinaris medialis thalami - Py Tractus pyramidalis - Pv Nucleus principalis n. trigemini - R Nucleus reticularis thalami - RTP Nucleus reticularis tegmenti pontis - SNc Substantia nigra — pars compacta - SNd Substantia nigra — pars diffusa - Sub Subiculum - TCT Tractus corticotectalis - VR Nucleus ventralis raphes - III Ventriculus tertius - IV Ventriculus quartus     

Responses of neurons in area VIP to self-induced and external visual motion

Single-unit recordings were obtained from directionally tuned neurons in area VIP (ventral intraparietal) in two rhesus monkeys under conditions of external (passive) and self-induced (active) visual motion. A large majority of neurons showed significant differences in directional tuning for passive and active visual motion with regard to preferred direction and tuning width. The differences in preferred directions are homogeneously distributed between similar and opposite. Generally, VIP neurons are more broadly tuned to passive than to active visual motion. This is most striking for the group of cells with widely different preferred directions in active and passive conditions. Response amplitudes to passive and active visual motion are not different in general, but are slightly smaller for passive visual motion if the preferred directions differ widely. We conclude that VIP neurons can distinguish between passive and active visual motion. Electronic Publication     

Phylogenetic analysis of classical swine fever virus (CSFV) field isolates from outbreaks in South and Central America

To date, there is little information concerning the epidemiological situation of classical swine fever (CSF) in the Americas. Besides summarizing the available data, genotyping of isolates from outbreaks in domestic pigs in several countries of South and Central America was performed. For this, a 190 base fragment of the E2 envelope glycoprotein gene was used. European strains and isolates, and historical isolates from the United States (US) were included for comparison. In contrast to the situation in most parts of Europe, where group 2 isolates predominate, it was found that all the isolates from the American continent analyzed belonged to group 1 and were further resolved into three subgroups. The Cuban isolates clustered in subgroup 1.2, whereas the isolates from Honduras and Guatemala clustered in subgroup 1.3. The remaining isolates from Argentina, Brazil, Colombia and Mexico generated four poorly resolved clusters in subgroup 1.1, together with the vaccine strains, with historical European and US isolates, and with a recent Russian isolate. While the vaccine strains and the historical European isolates formed a relatively distinct cluster, one of the US isolates clustered together with the Mexican, and another one with Colombian isolates. Historically, CSF (hog cholera) was observed almost simultaneously in the US and in Europe in the first half of the 19th century, and its origin remains a matter of discussion. Our results showed that the US isolates are closely related to isolates from South America, while appearance of isolates in Cuba on one hand and in Honduras and Guatemala on the other hand, seems to have been due to unrelated events. This allows to speculate that at least in the American continent, CSF virus may have appeared independently in several regions, and spreading may have been a secondary effect.     

Schedule-induced water and ethanol consumption as a function of interreinforcement interval in the squirrel monkey.

Lever pressing of two squirrel monkeys (Saimiri sciureus) was maintained under fixed-interval schedules of food delivery that were varied systematically from 1–10 min. First water and then 2% (V/V) ethanol solutions were available during the experimental sessions at each fixed-interval value. Drinking occurred immediately following the delivery of each pellet. The amount of water consumed increased markedly with increases in the length of the fixed-interval value from 1–9 min; drinking was decreased with one monkey at the 10 min fixed-interval, whereas with the second, drinking continued to increase. The amount of ethanol solution ingested was generally lower than that of water. With one animal ethanol consumption increased when the interval length was increased from 1–6 min, and then decreased beyond this point. With the second animal, ethanol drinking typically increased with increases in the fixed-interval length from 1–10 min. The amount of water consumed in the home cage generally decreased when the interval was lengthened from 1 to approximately 3 min and did not change substantially with further increases in the fixed-interval value.