Eye position effects on the neuronal activity of dorsal premotor cortex in the macaque monkey

Visual inputs to the brain are mapped in a retinocentric reference frame, but the motor system plans movements in a body-centered frame. This basic observation implies that the brain must transform target coordinates from one reference frame to another. Physiological studies revealed that the posterior parietal cortex may contribute a large part of such a transformation, but the question remains as to whether the premotor areas receive visual information, from the parietal cortex, readily coded in body-centered coordinates. To answer this question, we studied dorsal premotor cortex (PMd) neurons in two monkeys while they performed a conditional visuomotor task and maintained fixation at different gaze angles. Visual stimuli were presented on a video monitor, and the monkeys made limb movements on a panel of three touch pads located at the bottom of the monitor. A trial begins when the monkey puts its hand on the central pad. Then, later in the trial, a colored cue instructed a limb movement to the left touch pad if red or to the right one if green. The cues lasted for a variable delay, the instructed delay period, and their offset served as the go signal. The fixation spot was presented at the center of the screen or at one of four peripheral locations. Because the monkey's head was restrained, peripheral fixations caused a deviation of the eyes within the orbit, but for each fixation angle, the instructional cue was presented at nine locations with constant retinocentric coordinates. After the presentation of the instructional cue, 133 PMd cells displayed a phasic discharge (signal-related activity), 157 were tonically active during the instructed delay period (set-related or preparatory activity), and 104 were active after the go signal in relation to movement (movement-related activity). A large proportion of cells showed variations of the discharge rate in relation to limb movement direction, but only modest proportions were sensitive to the cue's location (signal, 43%; set, 34%; movement, 29%). More importantly, the activity of most neurons (signal, 74%; set, 79%; movement, 79%) varied significantly (analysis of variance, P < 0.05) with orbital eye position. A regression analysis showed that the neuronal activity varied linearly with eye position along the horizontal and vertical axes and can be approximated by a two-dimensional regression plane. These data provide evidence that eye position signals modulate the neuronal activity beyond sensory areas, including those involved in visually guided reaching limb movements. Further, they show that neuronal activity related to movement preparation and execution combines at least two directional parameters: arm movement direction and gaze direction in space. It is suggested that a substantial population of PMd cells codes limb movement direction in a head-centered reference frame.     

Visual latencies in areas V1 and V2 of the macaque monkey

Latencies to small flashing spots of light were measured in different layers of areas V1 and V2 in anesthetized and paralyzed macaque monkeys. The shortest latencies were found in layers 4C alpha and 4B of area V1. Latencies in layer 4C beta were on average 20 ms longer than those in 4C alpha and 4B. The shortest latencies in area V2 were observed in the infragranular layers and they did not differ significantly from those found in the infragranular layers in V1. Similarly, latencies in the supragranular layers of V2 were not significantly different from those measured in the supragranular layers of V1. These results show that, in area V1, neurons of the magnocellular pathway are activated on average 20 ms earlier than those of the parvocellular pathway. Our data also suggest that much processing begins simultaneously in areas V1 and V2.     

A visuo-somatomotor pathway through superior parietal cortex in the macaque monkey: cortical connections of areas V6 and V6A

This report addresses the connectivity of the cortex occupying middle to dorsal levels of the anterior bank of the parieto-occipital sulcus in the macaque monkey. We have previously referred to this territory, whose perimeter is roughly circumscribed by the distribution of interhemispheric callosal fibres, as area V6, or the 'V6 complex'. Following injections of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA-HRP) into this region, we examined the laminar organization of labelled cells and axonal terminals to attain indications of relative hierarchical status among the network of connected areas. A notable transition in the laminar patterns of the local, intrinsic connections prompted a sub-designation of the V6 complex itself into two separate areas, V6 and V6A, with area V6A lying dorsal, or dorsomedial to V6 proper. V6 receives ascending input from V2 and V3, ranks equal to V3A and V5, and provides an ascending input to V6A at the level above. V6A is not connected to area V2 and in general is less heavily linked to the earliest visual areas; in other respects, the two parts of the V6 complex share similar spheres of connectivity. These include regions of peripheral representation in prestriate areas V3, V3A and V5, parietal visual areas V5A/MST and 7a, other regions of visuo-somatosensory association cortex within the intraparietal sulcus and on the medial surface of the hemisphere, and the premotor cortex. Subcortical connections include the medial and lateral pulvinar, caudate nucleus, claustrum, middle and deep layers of the superior colliculus and pontine nuclei. From this pattern of connections, it is clear that the V6 complex is heavily engaged in sensory-motor integration. The specific somatotopic locations within sensorimotor cortex that receive this input suggest a role in controlling the trunk and limbs, and outward reaching arm movements. There is a secondary contribution to the brain's complex oculomotor circuitry. That the medial region of the cortex is devoted to tightly interconnected representations of the sensory periphery, both visual and somatotopic-which are routinely stimulated in concert-would appear to be an aspect of the global organization of the cortex which must facilitate multimodal integration.     

The effects of V4 and middle temporal (MT) area lesions on visual performance in the rhesus monkey

The effects of V4, MT, and combined V4 + MT lesions were assessed on a broad range of visual capacities that included measures of contrast sensitivity, wavelength and brightness discrimination, form vision, pattern vision, motion and flicker perception, stereopsis, and the selection of stimuli that were less prominent than those with which they appeared in stimulus arrays. The major deficit observed was a loss in the ability, after V4 lesions, to select such less prominent stimuli; this was the case irrespective of the manner in which the stimulus arrays were made visible, using either luminance, chrominance, motion, or stereoscopic depth as surface media. In addition, V4 lesions yielded mild deficits in color, brightness, and form vision whereas MT lesions yielded mild to moderate deficits in motion and flicker perception. Both lesions produced mild deficits in contrast sensitivity, shape-from-motion perception, and yielded increased reaction times on many of the tasks. The impairment resulting from combined V4 and MT lesions was not greater than the sum of the deficits of either lesion. None of the lesions produced significant deficits in stereopsis. The findings suggest that (1) area V4 is part of a neural system that is involved in extracting stimuli from the visual scene that elicit less neural activity early in the visual system than do other stimuli with which they appear and (2) several other extrastriate regions and more than just two major cortical processing streams contribute to the processing of basic visual functions in the extrastriate cortex.     

Callosally projecting neurons in the macaque monkey V1/V2 border are enriched in nonphosphorylated neurofilament protein

Previous immunohistochemical studies combined with retrograde tracing in macaque monkeys have demonstrated that corticocortical projections can be differentiated by their content of neurofilament protein. The present study analyzed the distribution of nonphosphorylated neurofilament protein in callosally projecting neurons located at the V1/V2 border. All of the retrogradely labeled neurons were located in layer III at the V1/V2 border and at an immediately adjacent zone of area V2. A quantitative analysis showed that the vast majority (almost 95%) of these interhemispheric projection neurons contain neurofilament protein immunoreactivity. This observation differs from data obtained in other sets of callosal connections, including homotypical interhemispheric projections in the prefrontal, temporal, and parietal association cortices, that were found to contain uniformly low proportions of neurofilament protein-immunoreactive neurons. Comparably, highly variable proportions of neurofilament protein-containing neurons have been reported in intrahemispheric corticocortical pathways, including feedforward and feedback visual connections. These results indicate that neurofilament protein is a prominent neurochemical feature that identifies a particular population of interhemispheric projection neurons at the V1/V2 border and suggest that this biochemical attribute may be critical for the function of this subset of callosal neurons.     

Processing of first- and second-order motion signals by neurons in area MT of the macaque monkey

Extrastriate cortical area MT is thought to process behaviorally important visual motion signals. Psychophysical studies suggest that visual motion signals may be analyzed by multiple mechanisms, a "first-order" one based on luminance, and a "second-order" one based upon higher level cues (e.g. contrast, flicker). Second-order motion is visible to human observers, but should be invisible to first-order motion sensors. To learn if area MT is involved in the analysis of second-order motion, we measured responses to first- and second-order gratings of single neurons in area MT (and in one experiment, in area V1) in anesthetized, paralyzed macaque monkeys. For each neuron, we measured directional and spatio-temporal tuning with conventional first-order gratings and with second-order gratings created by spatial modulation of the flicker rate of a random texture. A minority of MT and V1 neurons exhibited significant selectivity for direction or orientation of second-order gratings. In nearly all cells, response to second-order motion was weaker than response to first-order motion. MT cells with significant selectivity for second-order motion tended to be more responsive and more sensitive to luminance contrast, but were in other respects similar to the remaining MT neurons; they did not appear to represent a distinct subpopulation. For those cells selective for second-order motion, we found a correlation between the preferred directions of first- and second-order motion, and weak correlations in preferred spatial frequency. These cells preferred lower temporal frequencies for second-order motion than for first-order motion. A small proportion of MT cells seemed to remain selective and responsive for second-order motion. None of our small sample of V1 cells did. Cells in this small population, but not others, may perform "form-cue invariant" motion processing (Albright, 1992).     

Clustering of response selectivity in the medial superior temporal area of extrastriate cortex in the macaque monkey

The evolution of the medical responsibility cannot escape from the determining influence of the scientific progress, but it is also significantly influenced by sociological and psychological factors that often are more difficult to analyse. If the ethical rules express the physicians' obligations in legal terms, it perfectly determines the spirit which must drive every physician thus revealing his sense of responsibility. This concept of the medical responsibility distinguishes and differentiates itself from the penalty responsibility and from the compensation responsibility which only takes place in the context of the compensation for a harm caused. The acquisition of the prime sense of the responsibility is a product of a background dominated by the experience, the example, the conscience. The expression of the medical responsibility is most of all personal, but more and more fits in with the public health issues and becomes a collective responsibility. Finally in order to meet the more and more accurate specialists' demands, the physician's responsibility which must remain within the boundaries of his competence must be fulfilled in the frame of a team. This dimension imposes on him new regulations that affect the quality of the relationship between the various contributors. An evolution of the responsibility thus grows according to the progress and within the adapted scope of ethics.     

The influence of fixational eye movements on the response of neurons in area MT of the macaque

After milk ejection, piglets spend several minutes massaging their own teats on the sow. We examined whether this behaviour could be a mammalian counterpart to begging in young birds, and hence be explained by theories of honest begging. In one experiment, the behaviour of piglets was examined in relation to their previous milk intake. In each of 16 litters, one focal piglet was exposed to three treatments for three consecutive sucklings: 'no milk', where the piglet was withheld from the teat during milk ejection; 'extra milk', where it was fed 10 ml of extra milk directly after milk ejection; and 'control', when it received its normal intake. Average massage duration in the next three sucklings was significantly longer in the 'no milk' than in the control piglets. 'No milk' pigs massaged more intensely (number of massage movements/min), were more persistent in attempting to maintain udder contact and spent less time away from the udder. However, there were no significant differences between 'control' and 'extra milk' treatments. In a second experiment, in which we manually massaged teats for 0, 3 or 10 min, we found no significant effect of massage duration on milk output (measured by weighing piglets before and after milk ejection), although massage tended to increase output. We conclude that post-sucking massage in piglets has a number of aspects similar to honest begging in birds. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Evidence for direct connections between the hand region of the supplementary motor area and cervical motoneurons in the macaque monkey

In primates the corticospinal neurons of the hand representation of the primary motor cortex (M1) give rise to direct contacts with the cervical motoneurons that control distal forelimb muscles. We investigated, at the light-microscopy level, whether corticospinal cells present in the hand area of the supplementary motor area (SMA) also establish direct connections with cervical motoneurons, particularly those innervating hand and finger muscles. The hand representation of the M1 (two monkeys) or SMA (two monkeys) was located using intracortical microstimulation and injected with the anterograde tracer biotinylated dextran amine to label corticospinal terminals. Forearm muscles acting on the wrist and hand as well as hand muscles acting on the thumb and index finger, thus including those activated by intracortical stimulation, were injected with the retrograde tracer cholera-toxin B subunit, in order to label the motoneurons. A consistent zone of overlap between the two markers was found in the cervical cord. Close appositions between corticospinal axonal terminals and the somata or dendrites of motoneurons were found after injection in the M1, confirming previous observations. The new finding is the observation of similar close appositions after injection in the SMA, suggesting its control of hand movements in parallel with the M1.     

Object-based attention in the primary visual cortex of the macaque monkey

Typical natural visual scenes contain many objects, which need to be segregated from each other and from the background. Present theories subdivide the processes responsible for this segregation into a pre-attentive and attentive system. The pre-attentive system segregates image regions that 'pop out' rapidly and in parallel across the visual field. In the primary visual cortex, responses to pre-attentively selected image regions are enhanced. When objects do not segregate automatically from the rest of the image, the time-consuming attentive system is recruited. Here we investigate whether attentive selection is also associated with a modulation of firing rates in area V1 of the brain in monkeys trained to perform a curve-tracing task. Neuronal responses to the various segments of a target curve were simultaneously enhanced relative to responses evoked by a distractor curve, even if the two curves crossed each other. This indicates that object-based attention is associated with a response enhancement at the earliest level of the visual cortical processing hierarchy.     

碳热还原法制备锂离子电池正极材料Li3V2(PO4)3的研究

以LiCO3、V2O5、NH4H2PO4为原料,采用碳热还原法合成锂离子电池正极材料Li3V2(PO4)3(LVP).根据TG分析得到制备样品的温度范围.对所得材料分别进行了XRD、粉末微电极循环伏安及恒电流充放电测试.XRD分析表明, 850 ℃煅烧所得样品特征衍射峰型尖锐,晶体结构发育良好,为纯相的Li3V2(PO4)3;循环伏安测试表明,锂离子脱嵌分三步进行,循环伏安曲线对称性好;合成的正极材料在7 mA/g恒流充放电,首次充、放电比容量分别为129.8 mA·h/g、116.8 mA·h/g,充放电效率达90%,循环性能有待提高.材料中过量碳的加入提高了其充、放电比容量,使其循环性能有所改善.     

碳源对Li3V2(PO4)3正极材料性能的影响

采用高温碳热还原法在惰性气氛下合成单斜晶型Li3V2(PO4)3正极材料,考察活性炭、蔗糖和酚醛树脂等不同碳源对目标材料性能的影响。采用XRD、FE-SEM和电化学测试等手段对目标材料进行结构表征和性能测试。结果显示,以酚醛树脂作为碳源的正极材料具有优良的电化学性能,首次放电比容量达138 mA.h/g,到第10次循环容量降至122.9 mA.h/g。酚醛树脂作碳源能在加热的过程中固化交联成三维的网状结构,极有效地限制了粒子的进一步长大,材料粒径最小。     

Comparative analysis of calcium-binding protein-immunoreactive neuronal populations in the auditory and visual systems of the bottlenose dolphin (Tursiops truncatus) and the macaque monkey (Macaca fascicularis)

This study compares the distribution of three calcium-binding protein-immunoreactive (CaBP-immunoreactive) neuronal populations (calretinin-, calbindin- and parvalbumin-immunoreactive) in the visual and auditory systems in two mammalian species which are fundamentally different in their evolutionary traits and ecology, the aquatic toothed whale Tursiops truncatus (bottlenose dolphin) and the terrestrial Old World primate, Macaca fascicularis (long-tailed macaque). Immunocytochemical analyses, combined with computerized morphometry revealed that in the visual and auditory systems of the bottlenose dolphin, calretinin and calbindin are the prevalent calcium-binding proteins, whereas parvalbumin is present in very few neurons. The prevalence of calretinin and calbindin-immunoreactive neurons is especially obvious in the auditory system of this species. In both auditory and visual systems of the macaque monkey, the parvalbumin-immunoreactive neurons are present in comparable or higher densities than the calretinin and calbindin-immunoreactive neurons. In some structures of the visual and auditory systems of the macaque monkey, the calretinin- and calbindin-immunoreactive neurons are nearly absent. The prevalence of parvalbumin-immunoreactive over calretinin- and calbindin-immunoreactive neurons is particularly prominent in the visual system of primates. Thus, the dominant sensory systems in both aquatic and terrestrial mammals are enriched in specific phenotypes of calcium-binding protein-immunoreactive neurons.     

Efficacy of 6-chloro-2'',3''-dideoxyguanosine (6-Cl-ddG) on rhesus macaque monkeys chronically infected with simian immunodeficiency virus (SIVmac239)

The object of the present work was to study the relationship between acute pancreatitis (PA) and hyperlipidic diets. PA was induced by Caerulein (CE) by a single intraperitoneal doses (50 mcg/kg), after feeding the rats during 6 weeks with an hyperlipidic diet (45%). Rats with a normolipidic diet (lipids 5%) were used as control. The increase of serum lipase was similar in both groups treated with CE (control and with hyperlipidic diet). There were increase of interstitial edema, cariorrexis and a specially marked increase in the level of vacuolization of acinar cells with respect to the control group. It was concluded that chronic hyperlipidic diet increases histopathologic lesions in PA induced by CE in rats.     

The dorsomedial cortical visual area: a third tier area in the occipital lobe of the owl monkey (Aotus trivirgatus)

In the owl monkey, microelectrode mapping of Brodmann's area 19 indicates that this region contains part or all of at least 5 separate representations of the visual field, each of which adjoins the anterior border of V II and collectively are termed the third tier of cortical visual areas (V I is the first tier; V II is the second tier). Described in detail in this report is one of the third tier areas which is located on the dorsal surface and the adjacent medial wall of the occipital lobe and corresponds to a densely myelinated zone of cortex. In this dorsomedial area (DM), the representation of the horizontal meridian is partially split, and thus, like V II (see ref. 4) and the dorsolateral crescent5, DM is a second order transformation of the visual hemifield. In one abnormal owl monkey, a portion of the upper quadrant was represented twice in DM. This abnormal case may provide some clues as to how the normal pattern of visuotopic organization is established in the developing brain.     

Variations in fundamental frequency peak position in Japanese macaque (Macaca fuscata) coo calls.

Japanese macaques (Macaca fuscata) produce coo calls whose use in various contexts is correlated with differences in the relative temporal position of the peak value of a call's fundamental frequency (S. Green, 1975). Studies have produced conflicting results about both the location of the category boundary between smooth early high and smooth late high coo subtypes and macaques' perceptual sensitivity to variations in peak position. In this study, fundamental frequency peak positions were measured in 578 coos produced by 8 captive adult female Japanese macaques in order to test whether calls with peak positions close to either of 2 hypothesized boundaries occurred at low rates. Overall, such calls were found to occur at rates equal to or higher than predicted by chance. Peak position varied more consistently between animals than by behavioral context. The results may indicate that peak position in coos does not form 2 distinct categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Linking of serially ordered lists by macaque monkeys (Macaca mulatta): List position influences.

Five monkeys (Macaca mulatta) were trained on 2 sets of 3 5-item serially ordered lists. Then, each set was either linked or not in a counterbalanced, within-subject design. Linking entailed training on the 2 pairs that ordered the 3 5-item fists into a single overall 15-item series. Choices on novel pairings after linking conditions attempted to define the unique contributions of knowledge of within-list ordinal position and between-lists link training. With linkage, the series was immediately treated as a 15-item ordered list. Without linkage, choices reflected list positions from initial learning, but continued testing with directional reward yielded gradual ordering into a 15-itern list. Apparently, monkeys remembered and used initial list-position information, but linkage allowed inference of an integrated serial relationship among items. Results supported primate list memory as an organizational process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

微弧氧化法直接合成CaTi4(PO4)6生物陶瓷膜

采用微弧氧化技术, 在钛基体表面生长出一层致密的、结合良好的金属磷酸盐生物陶瓷膜, 考察了微弧氧化时间与电流对生成陶瓷膜的影响. 并借助XRD、 SEM等测试手段, 研究了该生物陶瓷膜的物相组成和表面形貌特征. 研究结果表明该金属磷酸盐生物陶瓷膜主要物相是CaTi4(PO4)6(CTP). 本技术与粉末等离子喷涂技术相比, 具有流程短、能耗小、易于实现的优点.     

An electrophysiological study of the postnatal development of the corticospinal system in the macaque monkey

We characterized toxin-insensitive calcium currents expressed by acutely dissociated embryonic dorsal root ganglion neurons. In the presence of 3 microM omega-conotoxin-GVIA, 3 microM nitrendipine and either 500 nM omega-agatoxin-IVA or 500 nM omega-conotoxin-MVIIC to inhibit N-, L- and P/Q-type currents, respectively, all neurons expressed two residual currents: a T-type and another which we referred to as toxin-resistant current. The toxin-resistant current (i) consisted of an inactivating and a sustained components, (ii) had a threshold of activation and a steady-state inactivation comprised between that of the T-type current and that of the other high-voltage-activated currents, (iii) had the same permeability for barium and calcium used as charge carriers, (iv) was highly sensitive to both cadmium and nickel; and (v) was insensitive to 500 microM amiloride which abolished the T-type at this concentration. The properties of the toxin-resistant current are very similar to those of the currents expressed in oocytes following injection of alpha(1E) subunits which we demonstrated to be present in these neurons. Therefore a component of the toxin-resistant current calcium channels in sensory neurons may be closely related to those calcium channels formed by alpha(1E) subunits.     

Targeted disruption of the V(H) 81X gene: influence on the B cell repertoire

We have generated a mutant mouse in which the most D-proximal V(H) gene (V(H)81X) has been disrupted by introducing a neomycin-resistance gene into the V(H)81X exon by means of gene targeting in embryonic stem cells. The mutant mice generated are unable to express the V(H)81X gene but appear to display a normal pattern of B cell differentiation as well as normal numbers of bone marrow and peripheral B cells from fetal life all through ontogeny. They mount normal immune responses to several different antigens tested. In contrast, the distribution of V(H) gene rearrangements in the V(H)7183 family is altered in homozygous mutant mice. Thus, the antibody repertoire of the targeted mice is modified, at least as far as the expression of V(H)7183 genes is concerned.