Bilateral receptive field neurons in the hindlimb region of the postcentral somatosensory cortex in awake macaque monkeys

Single-neuron activities were recorded in the hindlimb region of the primary somatosensory cortex and part of area 5 in awake Japanese monkeys. A total of 1050 units were isolated from five hemispheres of four animals. Receptive fields (RFs) and submodalities were identified for 90% of isolated neurons in areas 3a and 3b. The percentage decreased as the recoding site moved to the more caudal areas. Deep or skin submodality neurons were dominant in area 3a or area 3b, respectively. Deep submodality neurons increased in more caudal areas and were the majority in areas 2 and 5. These observations were consistent with those in the hand and/or digit or arm and/or trunk region. The identified neurons were classified by their RF positions into four types: the foot, leg, foot and leg, or hindlimb and other body parts type. Among 831 identified neurons, 33 neurons had bilateral RFs, 14 had ipsilateral RFs, and the rest (N=784) had contralateral RFs. The relative incidence of neurons with bilateral or ipsilateral RFs among identified neurons was less than 1% in areas 3a, 3b, and 1, and 16% or 25% in areas 2 or 5, respectively. Within areas 2 and 5, the percentage of neurons with bilateral or ipsilateral RFs was significantly smaller in the foot type (5%) than in other RF types (24-57%). RFs of the foot type were on the sole or single toe but never on multiple toes. These observations contrasted with the previous findings that neurons with bilateral RFs were more frequently seen in the hand and/or digit region and that RFs on multiple digit tips were dominant there. The present study thus demonstrated that neurons with bilateral RFs do exist in the hindlimb region. Similarly to the forelimb region, they were found mostly in areas 2 and 5, the caudalmost areas of the postcentral gyrus and hierarchically higher stages in information processing. The relative paucity of neurons with bilateral RFs on the foot, especially those with RFs on multiple toes, may reflect functional differences between the foot and the hand.     

双相气道正压无创机械通气上呼吸道影像分析

目的应用多层螺旋CT对患者不同通气状态下上呼吸道放射性成像,证实在全身麻醉无自主呼吸的条件下,双相气道正压(bi-level positive airway pressure,BiPAP)无创机械通气能克服上呼吸道阻力,实施有效的机械通气。方法选择拟实施全身麻醉的择期手术患者10例,分别对患者清醒自主呼吸、麻醉诱导后自主呼吸停止、BiPAP无创通气时头颈部正位和侧位作螺旋CT扫描。监测扫描过程的无创血压(NIBP)、脉搏氧饱和度(SpO2)、心率(HR)、自主呼吸频率(RR)。测量上呼吸道各软组织区(软腭后区RP、舌根后区RG、会厌区EPG)的最窄气道横截面左右径、前后径线长度及相应横截面积。结果头部正位麻醉诱导后各软组织区的最窄横截面左右径、前后径线长度及相应横截面积均比清醒时缩小(P<0.05),BiPAP通气时各截面径线和面积与清醒期比较差异仍有统计学意义(P<0.05,P<0.01)。头部侧位BiPAP通气时各径线和截面积与清醒时比较,差异无统计学意义。EPG区和RG区在BiPAP通气期的侧位截面积明显比正位时增大(P<0.05,P<0.01)。诱导期正、侧位SpO2均明显下降(P<0.01);头部正位BiPAP通气时与诱导期的SpO2比较虽有改善,但差异无统计学意义(P>0.05);头部侧位BiPAP通气时SpO2较诱导期明显升高(P<0.01),基本恢复到清醒期水平(P>0.05)。结论麻醉诱导后上呼吸道的通气面积明显减少,气道通畅度下降;头颈部侧位时上呼吸道各软组织区最狭窄处的通气截面积比正位时显著改善,以会厌区最明显。无明显上呼吸道梗阻性病史的成年患者全身麻醉时,头部侧位BiPAP无创通气能克服上呼吸道阻力,实施有效的机械通气,保证通气和氧合正常。     

Language processing from the perspective of electrical stimulation mapping

ABSTRACT

Electrical Stimulation (ES) is a neurostimulation technique that is used to localize language functions in the brain of people with intractable epilepsy and/or brain tumors. We reviewed 25 ES articles published between 1984 and 2018 and interpreted them from a cognitive neuropsychological perspective. Our aim was to highlight ES as a tool to further our understanding of cognitive models of language. We focused on associations and dissociations between cognitive functions within the framework of two non-neuroanatomically specified models of language. Also, we discussed parallels between the ES and the stroke literatures and showed how ES data can help us to generate hypotheses regarding how language is processed. A good understanding of cognitive models of language is essential to motivate task selection and to tailor surgical procedures, for example, by avoiding testing the same cognitive functions and understanding which functions may be more or less relevant to be tested during surgery.     

Respiratory chemoreflexes and effects of cortical activation state in urethane anesthetized rats

Urethane anesthetized (< 1 .3 g/kg), Sprague-Dawley (SD) rats spontaneously cycled between a cortically desynchronized state (State I) and a cortically synchronized state (State III), which were very similar to awake and slow wave sleep (SWS) states in unanesthetized animals, based on EEG criteria. These low levels of urethane anaesthesia did not cause significant respiratory depression or reductions in sensitivity to hypoxia (10% O2 in nitrogen) or hypercapnia (5% CO2 in air) in rats in either State I or State III. Thus, breathing frequency (fR), tidal volume (VT) and total ventilation (VTOT) all increased on cortical activation in urethane-anaesthetized rats whether breathing air, the hypoxic or the hypercapnic gas mixture, in a manner that was very similar to that observed in unanaesthetized animals. The relative sensitivity to hypoxia was greater in State III than State I, the relative sensitivity to CO2, overall, was equal in both states, State III occurred less often during hypoxia and hypercapnia, and hypoxic, urethane-anaesthetized rats sighed frequently, particularly in State I. This is also similar to the situation seen in unanesthetized rats. Given the similarities seen between urethane anesthetized rats in the present study and literature values for unanesthetized rats, the data suggest that urethane-anaesthetized rats provide a good model system for studying respiratory patterns and chemoreflexes as a function of cortical activation state.     

臂内侧入路臂丛阻滞麻醉的解剖学基础

目的：为臂内侧入路臂丛阻滞麻醉提供解剖学基础。方法：①尸体解剖观测臂内侧血管神经鞘；②模拟注射造影剂后X线造影和CT扫描观察造影剂扩散范围；③选择合适病例临床应用。结果：①臂内侧血管神经鞘与腋鞘相通；②臂内侧血管神经鞘注射有色液体后，鞘内各主要神经干均被染色；③造影剂可以于臂内侧鞘内向上、向下扩散；④临床应用225例，成功211例，成功率93．8％。结论：臂内侧人路臂丛阻滞麻醉具有操作简便，成功率高，无严重并发症的优点，特别适用于前臂及手部手术麻醉。     

Reflex inhibition of sympathetic activity during volume load in awake normotensive and spontaneously hypertensive rats

The reflex inhibition of the sympathetic activity in the splanchnic nerves was recorded upon volume expansion with blood in awake spontaneously hypertensive rats (SHR) and in normotensive Wistar-Kyoto rats (WKR) at an age of 16–20 weeks. At 10% blood volume expansion SHR showed a significantly greater nerve inhibition (43 %) in comparison with WKR (33 %). This augmented reflex response was not caused by the arterial baroreceptors, because the sensitivity of the arterial baroreceptor reflex arch, if anything, tended to be lower in SHR and the increase in arterial blood pressure upon volume load was also lower in SHR. It is suggested that the reason for this increased reflex inhibition in SHR is an augmented low pressure receptor response. The mechanism behind this is discussed. The most likely explanation is a decreased distensibility of the venous system, the systemic andlor the pulmonary veins.     

Arterial hypertension associated with the use of a tourniquet with either general or regional anaesthesia

A hypertensive patient with left cardiac enlargement developed marked hypertension under general anaesthesia, during which time a tourniquet was applied around his thigh. When the tourniquet was released, severe hypotension ensued which responded to therapy. The patient, however, died 16 h later of a myocardial infarction. Because of this incident, the anaesthetic and haemodynamic data of 699 patients who underwent limb surgery with a pneumatic tourniquet inflated for at least an hour were retrospectively examined using multivariate analysis. A 30% increase in systolic and/or diastolic arterial blood pressure occurred in 27% of the total patient material and in 67% of those who had had a general anaesthetic. There was a higher frequency of the occurrence of "tourniquet hypertension" with older age, longer operations and the operation site being the lower rather than the upper limb. Tourniquet hypertension rarely occurred in patients with spinal anaesthesia (2.7%) and brachial plexus blockade (2.5%), while those with intravenous regional anesthesia had a higher incidence (19%) of hypertension.     

Monitoring, past, present, future

Summary A little over 40 years ago, anesthesiology in the United States became recognized as a specialty. At that time, its practice was largely that of an art, the science of which was yet to come. A finger on the pulse, observation of color, skin turgor, perspiration, and perhaps a blood pressure cuff in adults, and an estimation of the reflex signs of anesthesia were the standards for the assessment of the patient status and the depth of anesthesia. How far have we come in the intervening years? The journey, as reflected in the experience of one physician, will be held up to the looking-glass; easily as astounding as that through which Alice passed.Caught as we are in the socio-economic climate of the present, how shall we react? Has the gadgetry and electronics of this day given us a meaningful cost-effective handle on a decreased morbidity and mortality? What impact is there on decision-making and outcome? What indeed is the contribution of the machine versus the newer agents, techniques, and the advanced educational milieu.The first attempts at monitoring were clearly directed toward the cardiovascular system. The devices developed were simple and non-invasive. The Riva-rocci method of measuring blood pressure was first applied in anesthesia by Harvey Cushing at the turn of the century. But it was 40 years before the electrocardiogram was introduced as an instrument of potential importance. It took another 25 years for it to have general acceptance, and even later for the anesthesiologist to become comfortable with it as a diagnostic tool. In the early 40s, Peterson, at Pennsylvania, began the applications of invasive blood pressure monitoring for clinical purposes. Subsequently, the use of the central venous catheter, and finally the Swan-Ganz catheter, became acceptable. The application for the technology of cardiac output was a long time in gaining clinical credence. However, this last link surely depended on the computer to make it a clinically useful instrument. The measurement of the cardiovascular system was first, because the means were there.The assessment of respiratory function was more cumbersome, and while the pneumotachygraph was available 40 years ago, its vagaries made it a research tool. Meters for respiration also were available, but too cumbersome for clinical use. The integration of respiratory measurements and blood gas analysis have gone hand-in-hand, the latter far outstripping the former in clinical utility. Shall it be invasive or non-invasive, what is the price? Lastly, our technology has introduced the means for what is a meaningful clinical measurement of neurological and neuromuscular activity. Nerve-muscle stimulators, electromyography, processed electroencephalogram, and the evoked potential as devices for assessment are only the beginning. In all this technological advance there is the black box and the electronic marvels that are part of this age. While invasive techniques surely have a place, the utilization of non-invasive techniques like the measurement of oxygen, carbon dioxide, and all the agents that we employ have changed forever the nature of our practice. Finally, the need to document the anesthesia course objectively will, and has already begun, to impact on our practice. How did we get where we are and where are we going will be explored in this personal journey.     

Splanchnic blood flow during halothane-relaxant anaesthesia in elderly patients

We have previously found that halothane-relaxant anaesthesia in elderly patients causes a change towards a hyperkinetic circulation, with a decrease in the arterial-mixed venous oxygen content difference. This could be attributed to vasodilation. In the present study the splanchnic contribution to these changes was investigated. Nine patients were studied during halothane-relaxant anaesthesia prior to surgery. During anaesthesia splanchnic blood flow was markedly reduced, while splanchnic oxygen uptake decreased only moderately compared with the awake level. This resulted in an increase in splanchnic oxygen extraction. It is concluded that the splanchnic vascular bed does not contribute to the "hyperkinetic" circulation during halothane anaesthesia.     

Central mediation of the conditioned taste aversion induced in rats by harmaline

The assumption that drugs used as unconditioned stimuli in conditioned taste aversion (CTA) studies act centrally was tested by comparing the effects of systemic and intracerebral injections of harmaline hydrochloride (H) in 340 rats. Intraperitoneal injection of 5–20 mg/kg but not of 2.5 mg/kg H administered 5 min after 15-min saccharin (0.1%) drinking decreased saccharin-water preference in a two-choice retention test, performed 48 h later, from 55% to 20%. Since CTA was not diminished when H (10 mg/kg) was injected into rats anesthetised immediately after saccharin drinking by pentobarbital (40 mg/kg), H (1.7–50 g) was administered intracerebrally to anesthetised rats fixed in the stereotaxic apparatus. Injection of 3–6 g H into the inferior olive elicited CTA comparable to that of systemic injection of 10 mg/kg H. Injections of 6 and 50 g H into cerebellum and bulbar reticular formation elicited weaker CTA while neocortical, hypothalamic and mesencephalic applications were ineffective. CTA could also be elicited when 50 g but not 6 g H was injected into the inferior olive 1 or 2 h after saccharin drinking. This delay-dependent effect and failure of non-contingent H administration to change saccharin preference indicates that the H-induced CTA is not contaminated by a non-specific increase in neophobia. It is concluded that H probably elicits CTA by activation of caudal bulbar structures, including the nucleus of the solitary tract, area postrema and lateral reticular formation.