James Prechtl - Academia.edu (original) (raw)
Papers by James Prechtl
Proceedings ... annual meeting, Electron Microscopy Society of America, Aug 1, 1986
Behavioral and electrophysiological analyses in rats indicate that the hepatic branch of the vagu... more Behavioral and electrophysiological analyses in rats indicate that the hepatic branch of the vagus nerve is an important pathway for chemoreceptive information from the hepatic portal circulation. Since morphological data have not been available on the rat hepatic branch, previous experiments have been designed and interpreted on the assumption the this nerve is a relatively simple and homogeneous structure. Our recent findings indicate that the hepatic shows a more complex although reproducible organization.
Journal of the autonomic nervous system, Oct 1, 1983
In order to provide a detailed surgical anatomy of the rat abdominal vagus, we examined pyridine ... more In order to provide a detailed surgical anatomy of the rat abdominal vagus, we examined pyridine silver-stained tissue from one group of normal animals and a second group that survived 9 months after vagotomy. In the normal sample, as has been established for man, there was considerable variability in the levels at which each of the vagal branches separated from the main trunks. Contrary to reports from dissection studies, most of the branches were not single fiber bundles but rather consisted of two or more separate bundles. At the extreme, the posterior gastric and coeliac branches each consisted of as many as 15 individual bundles. Even the main trunks of the subdiaphragmatic vagus were occasionally observed to have multiple components (anterior trunk, 13% of the cases; posterior, 25%). In addition to the classically recognized hepatic, anterior gastric, coeliac, and posterior gastric branches, we also observed an accessory coeliac branch of the anterior trunk in all animals. This accessory coeliac division originated just caudal to the hepatic branching and extended first laterally and then dorsally while running caudally to exit from the esophagus just before the separation of the coeliac branch from the posterior trunk. The vagi were observed to contain paraganglia consisting of islands of glomus cells, neurons, and extensive capillary beds, all situated within the perineurium. The paraganglia occurred in greatest frequency at the sites where the hepatic and coeliac branches divide from their respective trunks. Paraganglia were also observed peripherally within vagal branches; there they were most numerous within the coeliac branch and least numerous in the accessory coeliac. Other studies yielded evidence that regeneration had occurred after complete vagotomy. First, stumps of the branches distal to the resection scar contained axons. Central to the scar, axons grew out in all directions from the neuroma; some of them appeared to cross the scar and to reinnervate the distal stumps. Secondly, 30% of the animals in which regeneration was thought to be possible increased their insulin secretion in response to electrical stimulation of the cervical vagus. The implications of the above findings for experiments that involve manipulation or recording of the vagus are discussed.
The Biological Bulletin, Oct 1, 1995
activity of nearby receptors in the eye that see an object becomes correlated (5). The lateral ey... more activity of nearby receptors in the eye that see an object becomes correlated (5). The lateral eye is highly sensitive to the flickering light from the overhead waves. A large component of the light reflected from grey targets centers at -2-4 Hz which is the peak of the temporal transfer function of the eye (Fig. 1B; 6, 7, 8). Phototransduction mechanisms set the underlying shape of the transfer function, which two inhibitory processes then sharpen and amplify (6, 7). As a result, the power spectrum of the spike train recorded from receptors viewing the grey target grows considerably in the range of 2-4 Hz (Fig. 1 B). In this paper we show that a consideration of the natural environment of an animal can lead to a better understanding of its visual system. The Limulus eye appears to be adapted to a particular feature of its environment-the flickering light reflected off the carapace of a potential mate. These light signals help males detect a female irrespective of the contrast of her carapace. Frequency tuning of vision is not unique to horseshoe crabs and has been observed in many animals, such as cats (9) and humans (10). Perhaps their lighting environment also deserves a closer look. Supported by NSF grant BNS9309539 and NIH grants MH4974 1 and EY00667.
Brain Research, Mar 1, 1986
To characterize the lesion produced in the medulla oblongata by gold thioglucose (GTG), the prese... more To characterize the lesion produced in the medulla oblongata by gold thioglucose (GTG), the present experiment quantified the medullary damage in C57B 1 mice that had become obese after treatment with 800 mg/kg of GTG at 30 days of age. At the rostrocaudal level of the area postrema, the neurotoxin destroyed up to 75% of the neurons in the medial cell column of the dorsal motor nucleus of the vagus (DMX), while sparing the lateral pole of the nucleus. GTG also produced significant tissue loss in the central and commissural subnuclei of the nucleus of the solitary tract (NST). In contrast, the GTG lesion did not affect cell number in the hypoglossal nucleus or reduce the volume of the area postrema. Additional observations indicated that at 48-72 h after GTG administration the affected regions of the medulla already show advanced necrosis including cell loss and gliosis; and when the relative contributions of hypothalamic, DMX, and NST damage to the obesity that develops are evaluated statistically with partial correlational analysis, it appears the the obesity primarily correlates with the hypothalamic lesion produced by GTG. Roscoe B. Jackson Laboratory, Bar Harbor, ME, were group housed in plastic mouse cages. Purina Mouse Chow and water were provided ad libitum. The animals were individually weighed every other day. The colony was on a 14:10 light/dark schedule. Gold thioglucose treatment At thirty days of age, each mouse received an i.p. injection (0.01 ml/g body weight) of freshly prepared gold thioglucose (80 mg/mt isotonic saline) or the saline vehicle. All animals were 24-h food deprived at the time of injection (3 h before lights off), and food was not returned until lights-on the morning after the injection. Histology After the appropriate survival interval (3 months, except for early sacrifice groups), each animal was anesthetized with a lethal i.p. dose of Nembutal and then perfused through the heart with normal saline and 10% buffered formalin. The heads were removed and stored for one week in formalin. The brains were then removed and embedded in paraffin.
Anatomy and Embryology, Apr 1, 1987
The rat's vagal hepatic branch and associated tissues were studied using light and el... more The rat's vagal hepatic branch and associated tissues were studied using light and electron microscopy. Whole mounts, serial sections, and vascular endocasts were used to characterize the tissue from the anterior vagal trunk to the porta hepatis. Fiber number and caliber as well as intraneural organization were analyzed from complete cross-sectional electron micrographic montages of the hepatic branch sampled at
The Pavlovian journal of biological science, Oct 1, 1981
The motivational bases of the social reinforcement in human-dog relations were examined. In exper... more The motivational bases of the social reinforcement in human-dog relations were examined. In experiment I, performed on seven dogs, it was found that dogs were able to learn and sustain the natural responses of sitting, paw extension, and lying prostrate to conditional stimuli in the form of vocal commands reinforced only by social rewards given by the experimenter, such as petting and vocal encouragement. Overtraining did not produce deterioration of performance but, on the contrary, the continual decrease of latencies. It was evidenced that tactile stimulation plays an important role in social reward. In experiment II, instrumental responses to the auditory conditional stimuli were elaborated in two groups of dogs. The first group (nine dogs) was reinforced by food, and the second group (eight dogs) was reinforced exclusively by petting. A similar course of learning and level of performance during overtraining sessions in both groups indicated that petting serves as a good reinforcement, with rewarding value comparable to that of food reinforcement. It is suggested that a strong rewarding effect of pleasurable sensory stimuli occurs in the formation of the bond between dog and human and in the learning of different tasks.
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 1994
In mammalian brains, multielectrode recordings during sensory stimulation have revealed oscillati... more In mammalian brains, multielectrode recordings during sensory stimulation have revealed oscillations in different cortical areas that are transiently synchronous. These synchronizations have been hypothesized to support integration of sensory information or represent the operation of attentional mechanisms, but their stimulus requirements and prevalence are still unclear. Here I report an analogous synchronization in a reptilian cortex induced by moving visual stimuli. The synchronization, as measured by the coherence function, applies to spindle-like 20-Hz oscillations recorded with multiple electrodes implanted in the dorsal cortex and the dorsal ventricular ridge of the pond turtle. Additionally, widespread increases in coherence are observed in the 1to 2-Hz band, and widespread decreases in coherence are seen in the 10-and 30to 45-Hz bands. The 20-Hz oscillations induced by the moving bar or more natural stimuli are nonstationary and can be sustained for seconds. Early reptile studies may have interpreted similar spindles as electroencephalogram correlates of arousal; however, the absence of these spindles during arousing stimuli in the dark suggests a more specific role in visual processing. Thus, visually induced synchronous oscillations are not unique to the mammalian cortex but also occur in the visual area of the primitive three-layered cortex of reptiles.
Anatomy and Embryology, Feb 1, 1990
The present study provides a LM and EM inventory of the fibers of the rat abdominal vagus, includ... more The present study provides a LM and EM inventory of the fibers of the rat abdominal vagus, including dorsal and ventral trunks and the five primary branches. Whole mounts (n = 15) were prepared to characterize the branching patterns. A set of EM samples consisting of both trunks and all branches (i.e. dorsal and ventral gastric, dorsal and accessory celiac, and hepatic) were then obtained from each of six additional animals. A complete cross-sectional montage (x 10000) was prepared from each sample. All axons were counted, and greater than 10% of them were evaluated morphometrically. The means of unmyelinated axon diameters for each of the five branches were similar (0.75-0.83 microns). However, the shapes of the fiber size distributions, as summarized by their skew coefficients, revealed that the two gastric branches differed significantly from the two celiac branches; furthermore, the hepatic size distribution differed from all others. Most of the myelinated fibers (85%) in all branches were less than 2.6 microns in diameter and had sheath widths between 0.1 and 0.5 micron. The gastric branches, however, also contained a few larger myelinated fibers with sheath widths as great as 0.85 micron. Whole mounts revealed fibers which were not of supradiaphragmatic origin within all five vagal branches; these adventitial bundles were traced along the perineurium between adjacent branches. The sum of the fibers in the five branches (26930) was 21% more than the number counted in the parent trunks (22272); this excess probably reflects the adventitial fiber content. The whole mounts also showed that a large and regularly positioned paraganglion was associated with the dorsal branches. The structural profiles observed (i.e. unmyelinated and myelinated fibers size distributions, presence of extrinsic fascicles, glomus tissue content, etc.) differentiate the vagal branches into three morphologically distinct sets: a gastric pair, a celiac pair, and a hepatic branch. The fiber counts, when considered with observations of the numbers of efferents and adventitial fibers in the nerve, suggest that the percentage of efferent fibers is much higher than in all the widely accepted estimates found in the literature: efferent fibers may represent over a quarter of the total number of fibers.
Journal of comparative neurology, May 8, 1985
This experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues a... more This experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues and preserve positional information, untrimmed blocks of the subdiaphragmatic viscera (N = 22) were fixed, impregnated by using a pyridine-silver protocol, and double embedded. Each block was sectioned transversely at 7 pm, and a section every 70 pm from the diaphragm to the cardia was analyzed. The features of the section were traced and digitized for computer reconstruction. Included in the measurements were sizes and locations of bundles, fascicles, and paraganglia. The anterior and posterior vagi were consistently distinctive in size, distribution, cross-sectional shape, and paraganglionic content. In the most common pattern (41% of animals), the anterior trunk coursed longitudinally on the ventral surface of the esophagus, giving off at successively more distal levels the hepatic branch, the accessory coeliac branch and then the bundles of the anterior gastric branch. The posterior trunk separated into a coeliac branch and a posterior gastric branch, each consisting of numerous bundles, in the most distal quarter of the esophagus. Fifty-nine percent of all animals exhibited one or more significant variations in vagal organization (e.g., double primary trunks-41%, supernumerary branches-18%, or atypical branching sequences-9%). 1; equivalent to 32/rat, corrected for sampling) were found in each animal, and no branch was consistently devoid of paraganglia. Ninety-four percent of the paraganglia were located at nerve branch points. Some of the larger paraganglia contained at their central poles one to six neurons with soma diameters ranging from 14 to 22 pm. Four to 14 vagal paraganglia (mean = 8
Behavioral and Brain Sciences, Jun 1, 1990
The peripheral nervous system (PNS) has classically been separated into a somatic division compos... more The peripheral nervous system (PNS) has classically been separated into a somatic division composed of both afferent and efferent pathways and an autonomic division containing only efferents. J. N. Langley, who codified this asymmetrical plan at the beginning of the twentieth century, considered different afferents, including visceral ones, as candidates for inclusion in his concept of the "autonomic nervous system" (ANS), but he finally excluded all candidates for lack of any distinguishing histological markers. Langley's classification has been enormously influential in shaping modern ideas about both the structure and the function of the PNS. We survey recent information about the PNS and argue that many of the sensory neurons designated as "visceral" and "somatic" are in fact part of a histologically distinct group of afferents concerned primarily autonomic function. These afferents have traditionally been known as "small dark" neurons or B-neurons. In this target article we outline an association between autonomic and B-neurons based on ontogeny, cell phenotype, and functional relations, grouping them together as part of a common reflex system involved in homeostasis. This more parsimonious classification of the PNS, made possible by the identification of a group of afferents associated primarily with the ANS, avoids a number of confusions produced by the classical orientation. It may also have practical implications for an understanding of nociception, homeostatic reflexes, and the evolution of the nervous system.
Journal of Cognitive Neuroscience, 1993
Studies with auditory stimuli have established in humans that a mismatch potential (MMP) is elici... more Studies with auditory stimuli have established in humans that a mismatch potential (MMP) is elicited whenever a deviant stimulus is substituted for a standard stimulus in a train of monotonous standard stimuli presented at rates > 0.25 Hz. The MMP in humans is localized in the auditory cortex and is known as mrSmatch negativily, from its polarity in scalp recordings. It is hypothesized to reflect the operation of sensory memory and to be a necessary component of the auditory orienting response. To examine the generality of MMPs we used a visual mismatch paradigm with pond turtles (Psmuhys sm$fu) while recording with electrode arrays (200 Fm spacing) from near surface and deep visual projection areas within the forebrain and optic tectum. StuWrd stimuli were 10-sec trains of diffused strobe flashes presented at rates of 1-6 Hz against backgrounds of 2-11 lux. Deviant stimuli were brighter or dimmer flashes that followed the last standard flash. MMps were separated from visual evoked potentials by subtracting the response to the last standard flash of the train from the response to the same flash (bright or dim) when delivered as a deviant. Comparisons were also made with evoked potentials to isolated bright or dim flashes, that is, equal in frequency (1 per 12 sec) to the deviants but without intervening standard flashes. At tectal loci bright and dim deviants elicited net positivities that reached statistical significance in the period between 141 f
Electroencephalography and Clinical Neurophysiology, Jul 1, 1994
Visual omitted stimulus potentials (OSPs) were recorded from awake pond turtles with arrays of 3-... more Visual omitted stimulus potentials (OSPs) were recorded from awake pond turtles with arrays of 3-20 electrodes in the dorsal cortex (DC), dorsal ventricular ridge (DVR) and optic tectum. Since they are generally longer in duration than the interstimulus interval (ISI), the standard experiment is a short conditioning train of regular light or dark flashes (1-20 Hz) whose termination elicits the OSP. Tectal surface OSPs after trains > 7 Hz have 2 major positive peaks, P120-140 and P220-250 after the due-time of the first omission; after < 7 Hz down to the minimum of 1.5 Hz only the slower peak appears. Some deep tectal loci also have one to three 100 msec wide negative waves peaking at variable times from 200 to 1300 msec. Forebrain OSPs in DC and DVR are approximately 30 msec later and often include induced 17-25 Hz oscillations, not phase-locked and attenuated in averages. Both tectal and forebrain OSP main waves tend toward a constant latency after the due-time, over a wide range of ISis, as though the system expects a stimulus on schedule. Jitter of ISI around the mean does not greatly reduce the OSP. At all loci higher conditioning rates cause the amplitudes of the steady state response (SSR) VEPs to decline and of the OSPs to increase. Some similarities and correlations of regional amplitude fluctuations between OSPs and VEPs are noted. The OSP dynamics are consistent with the hypothesis of a postinhibitory rebound of temporally specific VEP components increasingly inhibited with higher stimulation rates; much of this response is retinal but each higher brain level further modulates. OSPs in this reptile are similar to those known in fish and to the "high frequency" type in humans, quite distinct in properties from the "low frequency" OSPs. It will be important to look at the high frequency type in laboratory mammals to determine whether they are present in the midbrain and retina, as in fish and reptiles.
The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes,... more The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes, and in ingestive behavior, yet little is known about their structure in any species. The aim of the present study is to provide a light and electron microscopic inventory of the fibers found in the two trunks and five primary branches of the abdominal vagus of the rat. To obtain an overview of the branching patterns and the organization of intraneural bundles, fifteen nerve whole mounts were prepared. For analyzing fiber content, electron microscopic samples of both trunks and all primary branches were obtained from each of six rats. From each sample a complete cross-sectional electron microscopic (EM) montage (X10,000) was prepared. All fibers were counted, and more than 10% of them were morphometrically evaluated with an image analyzer. The mean sizes of unmyelinated axons in each of the branches were similar (0.75-0.83 mu\mumum). But the shapes of the size distributions, as summarized by the coefficient of skewness, revealed significant differences between the bilateral gastric branches and the two celiac branches; the hepatic branch size distribution differed from all others. Most of the myelinated fibers (85%) in vagal branches were less than 2.6 mu\mumum in diameter, and had myelin sheath widths between 0.1 and 0.5 mu\mumum. The gastric branches, however, consistently contained a few larger myelinated fibers with sheath widths as great as 0.85 mu\mumum. The whole mounts showed that a large and regularly positioned paraganglion was associated with the dorsal vagal branches. Whole mounts also revealed fiber bundles within the vagal branches which were not of supradiaphragmatic origin; these adventitial bundles were traced along the perineurium between the adjacent vagal branches. The sum of the fibers in the combined branches was 21% more than the number of fibers counted in the parent trunks; this excess probably reflects the adventitial fiber content. The results demonstrate a cytological diversity in the abdominal vagus, as well as a specificity among the branches. The verification of subdiaphragmatic adventitial bundles within the primary branches is particularly relevant for the design and interpretation of experiments
Neuroreport, Sep 1, 1992
The selective effects of methohexital anesthesia were used to differentiate components of visual ... more The selective effects of methohexital anesthesia were used to differentiate components of visual event-related brain potentials (ERPs) in pond turtles (Pseudemys scripta). Tectal and forebrain omitted stimulus potentials (OSPs) were found to be particularly sensitive to the barbiturate; they are reversibly abolished while the large early wave of the forebrain flash visual evoked potential (VEP; 110-120 ms) is reduced by only 27 +/- 11% and that of the tectal VEP (55-65 ms) is increased by 40 +/- 12%. Concurrent with the decline of the OSP is the loss of late slow wave components (ca. greater than 125 ms) of forebrain and tectal VEPs and the appearance of irregularities in the responses of 5 Hz repetitive flashing. The barbiturate effects on the VEP and recovery cycles are remarkably similar to those reported in mammals.
Behavioral and Brain Sciences, Jun 1, 1990
The peripheral nervous system (PNS) has classically been separated into a somatic division compos... more The peripheral nervous system (PNS) has classically been separated into a somatic division composed of both afferent and efferent pathways and an autonomic division containing only efferents. J. N. Langley, who codified this asymmetrical plan at the beginning of the twentieth century, considered different afferents, including visceral ones, as candidates for inclusion in his concept of the "autonomic nervous system" (ANS), but he finally excluded all candidates for lack of any distinguishing histological markers. Langley's classification has been enormously influential in shaping modern ideas about both the structure and the function of the PNS. We survey recent information about the PNS and argue that many of the sensory neurons designated as "visceral" and "somatic" are in fact part of a histologically distinct group of afferents concerned primarily autonomic function. These afferents have traditionally been known as "small dark" neurons or B-neurons. In this target article we outline an association between autonomic and B-neurons based on ontogeny, cell phenotype, and functional relations, grouping them together as part of a common reflex system involved in homeostasis. This more parsimonious classification of the PNS, made possible by the identification of a group of afferents associated primarily with the ANS, avoids a number of confusions produced by the classical orientation. It may also have practical implications for an understanding of nociception, homeostatic reflexes, and the evolution of the nervous system.
The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes,... more The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes, and in ingestive behavior, yet little is known about their structure in any species. The aim of the present study is to provide a light and electron microscopic inventory of the fibers found in the two trunks and five primary branches of the abdominal vagus of the rat. To obtain an overview of the branching patterns and the organization of intraneural bundles, fifteen nerve whole mounts were prepared. For analyzing fiber content, electron microscopic samples of both trunks and all primary branches were obtained from each of six rats. From each sample a complete cross-sectional electron microscopic (EM) montage (X10,000) was prepared. All fibers were counted, and more than 10% of them were morphometrically evaluated with an image analyzer. The mean sizes of unmyelinated axons in each of the branches were similar (0.75-0.83 mu\mumum). But the shapes of the size distributions, as summarized by the coefficient of skewness, revealed significant differences between the bilateral gastric branches and the two celiac branches; the hepatic branch size distribution differed from all others. Most of the myelinated fibers (85%) in vagal branches were less than 2.6 mu\mumum in diameter, and had myelin sheath widths between 0.1 and 0.5 mu\mumum. The gastric branches, however, consistently contained a few larger myelinated fibers with sheath widths as great as 0.85 mu\mumum. The whole mounts showed that a large and regularly positioned paraganglion was associated with the dorsal vagal branches. Whole mounts also revealed fiber bundles within the vagal branches which were not of supradiaphragmatic origin; these adventitial bundles were traced along the perineurium between the adjacent vagal branches. The sum of the fibers in the combined branches was 21% more than the number of fibers counted in the parent trunks; this excess probably reflects the adventitial fiber content. The results demonstrate a cytological diversity in the abdominal vagus, as well as a specificity among the branches. The verification of subdiaphragmatic adventitial bundles within the primary branches is particularly relevant for the design and interpretation of experiments
Avian Pathology, 1982
ABSTRACT Morphological changes induced by a newly described avian virus in budgerigar (Melopsitta... more ABSTRACT Morphological changes induced by a newly described avian virus in budgerigar (Melopsittacus undulatus) tissues were examined with light and electron microscopes. Infected cells viewed with the light microscope were found to have enlarged nuclei containing marginated chromatin. Cytoplasmic contents were frequently clear in appearance. Tissues affected included skin, feather, follicle, kidney, uropygial gland, crop, lung, liver, heart, bone marrow, spleen and brain. Serum from infected birds contained viral particles. No tumours were found in affected birds. Electron microscopy demonstrated viral particles that were naked, predominantly icosehedral, and 42-49 nm in diameter. Occasional elongate forms of the virions were seen in kidney tissue. Small groups of virions were occasionally enclosed within nuclear and cytoplasmic membranes. Viral particles were observed in chicken embryo fibroblast cultures 18 hours post-inoculation. The particles first appeared in swollen nuclei and subsequently were found in the cytoplasm of more senescent cells. Cytoplasmic disruption and swollen rough endoplasmic reticulum were also observed in infected cells. Negatively stained preparations of the fluid from infected chicken embryo fibroblast cultures contained typical cubic viral particles as well as elongate forms similar to those seen in excised tissue preparations.
Optical monitoring of activity provides new kinds of information about brain function. Two exampl... more Optical monitoring of activity provides new kinds of information about brain function. Two examples are discussed in this article. First, the spike activity of many individual neurons in small ganglia can be determined. Second, the spatiotemporal characteristics of coherent activity in the brain can be directly measured. This article discusses both general characteristics of optical measurements (sources of noise) as well as more methodological aspects related to voltagesensitive dye measurements from the nervous system. # 1998 Chapman & Hall
Acta neurobiologiae experimentalis
Proceedings ... annual meeting, Electron Microscopy Society of America, Aug 1, 1986
Behavioral and electrophysiological analyses in rats indicate that the hepatic branch of the vagu... more Behavioral and electrophysiological analyses in rats indicate that the hepatic branch of the vagus nerve is an important pathway for chemoreceptive information from the hepatic portal circulation. Since morphological data have not been available on the rat hepatic branch, previous experiments have been designed and interpreted on the assumption the this nerve is a relatively simple and homogeneous structure. Our recent findings indicate that the hepatic shows a more complex although reproducible organization.
Journal of the autonomic nervous system, Oct 1, 1983
In order to provide a detailed surgical anatomy of the rat abdominal vagus, we examined pyridine ... more In order to provide a detailed surgical anatomy of the rat abdominal vagus, we examined pyridine silver-stained tissue from one group of normal animals and a second group that survived 9 months after vagotomy. In the normal sample, as has been established for man, there was considerable variability in the levels at which each of the vagal branches separated from the main trunks. Contrary to reports from dissection studies, most of the branches were not single fiber bundles but rather consisted of two or more separate bundles. At the extreme, the posterior gastric and coeliac branches each consisted of as many as 15 individual bundles. Even the main trunks of the subdiaphragmatic vagus were occasionally observed to have multiple components (anterior trunk, 13% of the cases; posterior, 25%). In addition to the classically recognized hepatic, anterior gastric, coeliac, and posterior gastric branches, we also observed an accessory coeliac branch of the anterior trunk in all animals. This accessory coeliac division originated just caudal to the hepatic branching and extended first laterally and then dorsally while running caudally to exit from the esophagus just before the separation of the coeliac branch from the posterior trunk. The vagi were observed to contain paraganglia consisting of islands of glomus cells, neurons, and extensive capillary beds, all situated within the perineurium. The paraganglia occurred in greatest frequency at the sites where the hepatic and coeliac branches divide from their respective trunks. Paraganglia were also observed peripherally within vagal branches; there they were most numerous within the coeliac branch and least numerous in the accessory coeliac. Other studies yielded evidence that regeneration had occurred after complete vagotomy. First, stumps of the branches distal to the resection scar contained axons. Central to the scar, axons grew out in all directions from the neuroma; some of them appeared to cross the scar and to reinnervate the distal stumps. Secondly, 30% of the animals in which regeneration was thought to be possible increased their insulin secretion in response to electrical stimulation of the cervical vagus. The implications of the above findings for experiments that involve manipulation or recording of the vagus are discussed.
The Biological Bulletin, Oct 1, 1995
activity of nearby receptors in the eye that see an object becomes correlated (5). The lateral ey... more activity of nearby receptors in the eye that see an object becomes correlated (5). The lateral eye is highly sensitive to the flickering light from the overhead waves. A large component of the light reflected from grey targets centers at -2-4 Hz which is the peak of the temporal transfer function of the eye (Fig. 1B; 6, 7, 8). Phototransduction mechanisms set the underlying shape of the transfer function, which two inhibitory processes then sharpen and amplify (6, 7). As a result, the power spectrum of the spike train recorded from receptors viewing the grey target grows considerably in the range of 2-4 Hz (Fig. 1 B). In this paper we show that a consideration of the natural environment of an animal can lead to a better understanding of its visual system. The Limulus eye appears to be adapted to a particular feature of its environment-the flickering light reflected off the carapace of a potential mate. These light signals help males detect a female irrespective of the contrast of her carapace. Frequency tuning of vision is not unique to horseshoe crabs and has been observed in many animals, such as cats (9) and humans (10). Perhaps their lighting environment also deserves a closer look. Supported by NSF grant BNS9309539 and NIH grants MH4974 1 and EY00667.
Brain Research, Mar 1, 1986
To characterize the lesion produced in the medulla oblongata by gold thioglucose (GTG), the prese... more To characterize the lesion produced in the medulla oblongata by gold thioglucose (GTG), the present experiment quantified the medullary damage in C57B 1 mice that had become obese after treatment with 800 mg/kg of GTG at 30 days of age. At the rostrocaudal level of the area postrema, the neurotoxin destroyed up to 75% of the neurons in the medial cell column of the dorsal motor nucleus of the vagus (DMX), while sparing the lateral pole of the nucleus. GTG also produced significant tissue loss in the central and commissural subnuclei of the nucleus of the solitary tract (NST). In contrast, the GTG lesion did not affect cell number in the hypoglossal nucleus or reduce the volume of the area postrema. Additional observations indicated that at 48-72 h after GTG administration the affected regions of the medulla already show advanced necrosis including cell loss and gliosis; and when the relative contributions of hypothalamic, DMX, and NST damage to the obesity that develops are evaluated statistically with partial correlational analysis, it appears the the obesity primarily correlates with the hypothalamic lesion produced by GTG. Roscoe B. Jackson Laboratory, Bar Harbor, ME, were group housed in plastic mouse cages. Purina Mouse Chow and water were provided ad libitum. The animals were individually weighed every other day. The colony was on a 14:10 light/dark schedule. Gold thioglucose treatment At thirty days of age, each mouse received an i.p. injection (0.01 ml/g body weight) of freshly prepared gold thioglucose (80 mg/mt isotonic saline) or the saline vehicle. All animals were 24-h food deprived at the time of injection (3 h before lights off), and food was not returned until lights-on the morning after the injection. Histology After the appropriate survival interval (3 months, except for early sacrifice groups), each animal was anesthetized with a lethal i.p. dose of Nembutal and then perfused through the heart with normal saline and 10% buffered formalin. The heads were removed and stored for one week in formalin. The brains were then removed and embedded in paraffin.
Anatomy and Embryology, Apr 1, 1987
The rat&#39;s vagal hepatic branch and associated tissues were studied using light and el... more The rat&#39;s vagal hepatic branch and associated tissues were studied using light and electron microscopy. Whole mounts, serial sections, and vascular endocasts were used to characterize the tissue from the anterior vagal trunk to the porta hepatis. Fiber number and caliber as well as intraneural organization were analyzed from complete cross-sectional electron micrographic montages of the hepatic branch sampled at
The Pavlovian journal of biological science, Oct 1, 1981
The motivational bases of the social reinforcement in human-dog relations were examined. In exper... more The motivational bases of the social reinforcement in human-dog relations were examined. In experiment I, performed on seven dogs, it was found that dogs were able to learn and sustain the natural responses of sitting, paw extension, and lying prostrate to conditional stimuli in the form of vocal commands reinforced only by social rewards given by the experimenter, such as petting and vocal encouragement. Overtraining did not produce deterioration of performance but, on the contrary, the continual decrease of latencies. It was evidenced that tactile stimulation plays an important role in social reward. In experiment II, instrumental responses to the auditory conditional stimuli were elaborated in two groups of dogs. The first group (nine dogs) was reinforced by food, and the second group (eight dogs) was reinforced exclusively by petting. A similar course of learning and level of performance during overtraining sessions in both groups indicated that petting serves as a good reinforcement, with rewarding value comparable to that of food reinforcement. It is suggested that a strong rewarding effect of pleasurable sensory stimuli occurs in the formation of the bond between dog and human and in the learning of different tasks.
Proceedings of the National Academy of Sciences of the United States of America, Dec 20, 1994
In mammalian brains, multielectrode recordings during sensory stimulation have revealed oscillati... more In mammalian brains, multielectrode recordings during sensory stimulation have revealed oscillations in different cortical areas that are transiently synchronous. These synchronizations have been hypothesized to support integration of sensory information or represent the operation of attentional mechanisms, but their stimulus requirements and prevalence are still unclear. Here I report an analogous synchronization in a reptilian cortex induced by moving visual stimuli. The synchronization, as measured by the coherence function, applies to spindle-like 20-Hz oscillations recorded with multiple electrodes implanted in the dorsal cortex and the dorsal ventricular ridge of the pond turtle. Additionally, widespread increases in coherence are observed in the 1to 2-Hz band, and widespread decreases in coherence are seen in the 10-and 30to 45-Hz bands. The 20-Hz oscillations induced by the moving bar or more natural stimuli are nonstationary and can be sustained for seconds. Early reptile studies may have interpreted similar spindles as electroencephalogram correlates of arousal; however, the absence of these spindles during arousing stimuli in the dark suggests a more specific role in visual processing. Thus, visually induced synchronous oscillations are not unique to the mammalian cortex but also occur in the visual area of the primitive three-layered cortex of reptiles.
Anatomy and Embryology, Feb 1, 1990
The present study provides a LM and EM inventory of the fibers of the rat abdominal vagus, includ... more The present study provides a LM and EM inventory of the fibers of the rat abdominal vagus, including dorsal and ventral trunks and the five primary branches. Whole mounts (n = 15) were prepared to characterize the branching patterns. A set of EM samples consisting of both trunks and all branches (i.e. dorsal and ventral gastric, dorsal and accessory celiac, and hepatic) were then obtained from each of six additional animals. A complete cross-sectional montage (x 10000) was prepared from each sample. All axons were counted, and greater than 10% of them were evaluated morphometrically. The means of unmyelinated axon diameters for each of the five branches were similar (0.75-0.83 microns). However, the shapes of the fiber size distributions, as summarized by their skew coefficients, revealed that the two gastric branches differed significantly from the two celiac branches; furthermore, the hepatic size distribution differed from all others. Most of the myelinated fibers (85%) in all branches were less than 2.6 microns in diameter and had sheath widths between 0.1 and 0.5 micron. The gastric branches, however, also contained a few larger myelinated fibers with sheath widths as great as 0.85 micron. Whole mounts revealed fibers which were not of supradiaphragmatic origin within all five vagal branches; these adventitial bundles were traced along the perineurium between adjacent branches. The sum of the fibers in the five branches (26930) was 21% more than the number counted in the parent trunks (22272); this excess probably reflects the adventitial fiber content. The whole mounts also showed that a large and regularly positioned paraganglion was associated with the dorsal branches. The structural profiles observed (i.e. unmyelinated and myelinated fibers size distributions, presence of extrinsic fascicles, glomus tissue content, etc.) differentiate the vagal branches into three morphologically distinct sets: a gastric pair, a celiac pair, and a hepatic branch. The fiber counts, when considered with observations of the numbers of efferents and adventitial fibers in the nerve, suggest that the percentage of efferent fibers is much higher than in all the widely accepted estimates found in the literature: efferent fibers may represent over a quarter of the total number of fibers.
Journal of comparative neurology, May 8, 1985
This experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues a... more This experiment analyzed the organization of the rat abdominal vagus. To spare delicate tissues and preserve positional information, untrimmed blocks of the subdiaphragmatic viscera (N = 22) were fixed, impregnated by using a pyridine-silver protocol, and double embedded. Each block was sectioned transversely at 7 pm, and a section every 70 pm from the diaphragm to the cardia was analyzed. The features of the section were traced and digitized for computer reconstruction. Included in the measurements were sizes and locations of bundles, fascicles, and paraganglia. The anterior and posterior vagi were consistently distinctive in size, distribution, cross-sectional shape, and paraganglionic content. In the most common pattern (41% of animals), the anterior trunk coursed longitudinally on the ventral surface of the esophagus, giving off at successively more distal levels the hepatic branch, the accessory coeliac branch and then the bundles of the anterior gastric branch. The posterior trunk separated into a coeliac branch and a posterior gastric branch, each consisting of numerous bundles, in the most distal quarter of the esophagus. Fifty-nine percent of all animals exhibited one or more significant variations in vagal organization (e.g., double primary trunks-41%, supernumerary branches-18%, or atypical branching sequences-9%). 1; equivalent to 32/rat, corrected for sampling) were found in each animal, and no branch was consistently devoid of paraganglia. Ninety-four percent of the paraganglia were located at nerve branch points. Some of the larger paraganglia contained at their central poles one to six neurons with soma diameters ranging from 14 to 22 pm. Four to 14 vagal paraganglia (mean = 8
Behavioral and Brain Sciences, Jun 1, 1990
The peripheral nervous system (PNS) has classically been separated into a somatic division compos... more The peripheral nervous system (PNS) has classically been separated into a somatic division composed of both afferent and efferent pathways and an autonomic division containing only efferents. J. N. Langley, who codified this asymmetrical plan at the beginning of the twentieth century, considered different afferents, including visceral ones, as candidates for inclusion in his concept of the "autonomic nervous system" (ANS), but he finally excluded all candidates for lack of any distinguishing histological markers. Langley's classification has been enormously influential in shaping modern ideas about both the structure and the function of the PNS. We survey recent information about the PNS and argue that many of the sensory neurons designated as "visceral" and "somatic" are in fact part of a histologically distinct group of afferents concerned primarily autonomic function. These afferents have traditionally been known as "small dark" neurons or B-neurons. In this target article we outline an association between autonomic and B-neurons based on ontogeny, cell phenotype, and functional relations, grouping them together as part of a common reflex system involved in homeostasis. This more parsimonious classification of the PNS, made possible by the identification of a group of afferents associated primarily with the ANS, avoids a number of confusions produced by the classical orientation. It may also have practical implications for an understanding of nociception, homeostatic reflexes, and the evolution of the nervous system.
Journal of Cognitive Neuroscience, 1993
Studies with auditory stimuli have established in humans that a mismatch potential (MMP) is elici... more Studies with auditory stimuli have established in humans that a mismatch potential (MMP) is elicited whenever a deviant stimulus is substituted for a standard stimulus in a train of monotonous standard stimuli presented at rates > 0.25 Hz. The MMP in humans is localized in the auditory cortex and is known as mrSmatch negativily, from its polarity in scalp recordings. It is hypothesized to reflect the operation of sensory memory and to be a necessary component of the auditory orienting response. To examine the generality of MMPs we used a visual mismatch paradigm with pond turtles (Psmuhys sm$fu) while recording with electrode arrays (200 Fm spacing) from near surface and deep visual projection areas within the forebrain and optic tectum. StuWrd stimuli were 10-sec trains of diffused strobe flashes presented at rates of 1-6 Hz against backgrounds of 2-11 lux. Deviant stimuli were brighter or dimmer flashes that followed the last standard flash. MMps were separated from visual evoked potentials by subtracting the response to the last standard flash of the train from the response to the same flash (bright or dim) when delivered as a deviant. Comparisons were also made with evoked potentials to isolated bright or dim flashes, that is, equal in frequency (1 per 12 sec) to the deviants but without intervening standard flashes. At tectal loci bright and dim deviants elicited net positivities that reached statistical significance in the period between 141 f
Electroencephalography and Clinical Neurophysiology, Jul 1, 1994
Visual omitted stimulus potentials (OSPs) were recorded from awake pond turtles with arrays of 3-... more Visual omitted stimulus potentials (OSPs) were recorded from awake pond turtles with arrays of 3-20 electrodes in the dorsal cortex (DC), dorsal ventricular ridge (DVR) and optic tectum. Since they are generally longer in duration than the interstimulus interval (ISI), the standard experiment is a short conditioning train of regular light or dark flashes (1-20 Hz) whose termination elicits the OSP. Tectal surface OSPs after trains > 7 Hz have 2 major positive peaks, P120-140 and P220-250 after the due-time of the first omission; after < 7 Hz down to the minimum of 1.5 Hz only the slower peak appears. Some deep tectal loci also have one to three 100 msec wide negative waves peaking at variable times from 200 to 1300 msec. Forebrain OSPs in DC and DVR are approximately 30 msec later and often include induced 17-25 Hz oscillations, not phase-locked and attenuated in averages. Both tectal and forebrain OSP main waves tend toward a constant latency after the due-time, over a wide range of ISis, as though the system expects a stimulus on schedule. Jitter of ISI around the mean does not greatly reduce the OSP. At all loci higher conditioning rates cause the amplitudes of the steady state response (SSR) VEPs to decline and of the OSPs to increase. Some similarities and correlations of regional amplitude fluctuations between OSPs and VEPs are noted. The OSP dynamics are consistent with the hypothesis of a postinhibitory rebound of temporally specific VEP components increasingly inhibited with higher stimulation rates; much of this response is retinal but each higher brain level further modulates. OSPs in this reptile are similar to those known in fish and to the "high frequency" type in humans, quite distinct in properties from the "low frequency" OSPs. It will be important to look at the high frequency type in laboratory mammals to determine whether they are present in the midbrain and retina, as in fish and reptiles.
The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes,... more The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes, and in ingestive behavior, yet little is known about their structure in any species. The aim of the present study is to provide a light and electron microscopic inventory of the fibers found in the two trunks and five primary branches of the abdominal vagus of the rat. To obtain an overview of the branching patterns and the organization of intraneural bundles, fifteen nerve whole mounts were prepared. For analyzing fiber content, electron microscopic samples of both trunks and all primary branches were obtained from each of six rats. From each sample a complete cross-sectional electron microscopic (EM) montage (X10,000) was prepared. All fibers were counted, and more than 10% of them were morphometrically evaluated with an image analyzer. The mean sizes of unmyelinated axons in each of the branches were similar (0.75-0.83 mu\mumum). But the shapes of the size distributions, as summarized by the coefficient of skewness, revealed significant differences between the bilateral gastric branches and the two celiac branches; the hepatic branch size distribution differed from all others. Most of the myelinated fibers (85%) in vagal branches were less than 2.6 mu\mumum in diameter, and had myelin sheath widths between 0.1 and 0.5 mu\mumum. The gastric branches, however, consistently contained a few larger myelinated fibers with sheath widths as great as 0.85 mu\mumum. The whole mounts showed that a large and regularly positioned paraganglion was associated with the dorsal vagal branches. Whole mounts also revealed fiber bundles within the vagal branches which were not of supradiaphragmatic origin; these adventitial bundles were traced along the perineurium between the adjacent vagal branches. The sum of the fibers in the combined branches was 21% more than the number of fibers counted in the parent trunks; this excess probably reflects the adventitial fiber content. The results demonstrate a cytological diversity in the abdominal vagus, as well as a specificity among the branches. The verification of subdiaphragmatic adventitial bundles within the primary branches is particularly relevant for the design and interpretation of experiments
Neuroreport, Sep 1, 1992
The selective effects of methohexital anesthesia were used to differentiate components of visual ... more The selective effects of methohexital anesthesia were used to differentiate components of visual event-related brain potentials (ERPs) in pond turtles (Pseudemys scripta). Tectal and forebrain omitted stimulus potentials (OSPs) were found to be particularly sensitive to the barbiturate; they are reversibly abolished while the large early wave of the forebrain flash visual evoked potential (VEP; 110-120 ms) is reduced by only 27 +/- 11% and that of the tectal VEP (55-65 ms) is increased by 40 +/- 12%. Concurrent with the decline of the OSP is the loss of late slow wave components (ca. greater than 125 ms) of forebrain and tectal VEPs and the appearance of irregularities in the responses of 5 Hz repetitive flashing. The barbiturate effects on the VEP and recovery cycles are remarkably similar to those reported in mammals.
Behavioral and Brain Sciences, Jun 1, 1990
The peripheral nervous system (PNS) has classically been separated into a somatic division compos... more The peripheral nervous system (PNS) has classically been separated into a somatic division composed of both afferent and efferent pathways and an autonomic division containing only efferents. J. N. Langley, who codified this asymmetrical plan at the beginning of the twentieth century, considered different afferents, including visceral ones, as candidates for inclusion in his concept of the "autonomic nervous system" (ANS), but he finally excluded all candidates for lack of any distinguishing histological markers. Langley's classification has been enormously influential in shaping modern ideas about both the structure and the function of the PNS. We survey recent information about the PNS and argue that many of the sensory neurons designated as "visceral" and "somatic" are in fact part of a histologically distinct group of afferents concerned primarily autonomic function. These afferents have traditionally been known as "small dark" neurons or B-neurons. In this target article we outline an association between autonomic and B-neurons based on ontogeny, cell phenotype, and functional relations, grouping them together as part of a common reflex system involved in homeostasis. This more parsimonious classification of the PNS, made possible by the identification of a group of afferents associated primarily with the ANS, avoids a number of confusions produced by the classical orientation. It may also have practical implications for an understanding of nociception, homeostatic reflexes, and the evolution of the nervous system.
The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes,... more The abdominal branches of the vagus nerve are involved in vital digestive and metabolic reflexes, and in ingestive behavior, yet little is known about their structure in any species. The aim of the present study is to provide a light and electron microscopic inventory of the fibers found in the two trunks and five primary branches of the abdominal vagus of the rat. To obtain an overview of the branching patterns and the organization of intraneural bundles, fifteen nerve whole mounts were prepared. For analyzing fiber content, electron microscopic samples of both trunks and all primary branches were obtained from each of six rats. From each sample a complete cross-sectional electron microscopic (EM) montage (X10,000) was prepared. All fibers were counted, and more than 10% of them were morphometrically evaluated with an image analyzer. The mean sizes of unmyelinated axons in each of the branches were similar (0.75-0.83 mu\mumum). But the shapes of the size distributions, as summarized by the coefficient of skewness, revealed significant differences between the bilateral gastric branches and the two celiac branches; the hepatic branch size distribution differed from all others. Most of the myelinated fibers (85%) in vagal branches were less than 2.6 mu\mumum in diameter, and had myelin sheath widths between 0.1 and 0.5 mu\mumum. The gastric branches, however, consistently contained a few larger myelinated fibers with sheath widths as great as 0.85 mu\mumum. The whole mounts showed that a large and regularly positioned paraganglion was associated with the dorsal vagal branches. Whole mounts also revealed fiber bundles within the vagal branches which were not of supradiaphragmatic origin; these adventitial bundles were traced along the perineurium between the adjacent vagal branches. The sum of the fibers in the combined branches was 21% more than the number of fibers counted in the parent trunks; this excess probably reflects the adventitial fiber content. The results demonstrate a cytological diversity in the abdominal vagus, as well as a specificity among the branches. The verification of subdiaphragmatic adventitial bundles within the primary branches is particularly relevant for the design and interpretation of experiments
Avian Pathology, 1982
ABSTRACT Morphological changes induced by a newly described avian virus in budgerigar (Melopsitta... more ABSTRACT Morphological changes induced by a newly described avian virus in budgerigar (Melopsittacus undulatus) tissues were examined with light and electron microscopes. Infected cells viewed with the light microscope were found to have enlarged nuclei containing marginated chromatin. Cytoplasmic contents were frequently clear in appearance. Tissues affected included skin, feather, follicle, kidney, uropygial gland, crop, lung, liver, heart, bone marrow, spleen and brain. Serum from infected birds contained viral particles. No tumours were found in affected birds. Electron microscopy demonstrated viral particles that were naked, predominantly icosehedral, and 42-49 nm in diameter. Occasional elongate forms of the virions were seen in kidney tissue. Small groups of virions were occasionally enclosed within nuclear and cytoplasmic membranes. Viral particles were observed in chicken embryo fibroblast cultures 18 hours post-inoculation. The particles first appeared in swollen nuclei and subsequently were found in the cytoplasm of more senescent cells. Cytoplasmic disruption and swollen rough endoplasmic reticulum were also observed in infected cells. Negatively stained preparations of the fluid from infected chicken embryo fibroblast cultures contained typical cubic viral particles as well as elongate forms similar to those seen in excised tissue preparations.
Optical monitoring of activity provides new kinds of information about brain function. Two exampl... more Optical monitoring of activity provides new kinds of information about brain function. Two examples are discussed in this article. First, the spike activity of many individual neurons in small ganglia can be determined. Second, the spatiotemporal characteristics of coherent activity in the brain can be directly measured. This article discusses both general characteristics of optical measurements (sources of noise) as well as more methodological aspects related to voltagesensitive dye measurements from the nervous system. # 1998 Chapman & Hall
Acta neurobiologiae experimentalis