Development of the projection from the nucleus of the brachium of the inferior colliculus to the superior colliculus in the ferret

Neurons in the deeper layers of the superior colliculus (SC) have spatially tuned receptive fields that are arranged to form a map of auditory space. The spatial tuning of these neurons emerges gradually in an experience-dependent manner after the onset of hearing, but the relative contributions of peripheral and central factors in this process of maturation are unknown. We have studied the postnatal development of the projection to the ferret SC from the nucleus of the brachium of the inferior colliculus (nBIC), its main source of auditory input, to determine whether the emergence of auditory map topography can be attributed to anatomical rewiring of this projection. The pattern of retrograde labeling produced by injections of fluorescent microspheres in the SC on postnatal day (P) 0 and just after the age of hearing onset (P29), showed that the nBIC-SC projection is topographically organized in the rostrocaudal axis, along which sound azimuth is represented, from birth. Injections of biotinylated dextran amine-fluorescein into the nBIC at different ages (P30, 60, and 90) labeled axons with numerous terminals and en passant boutons throughout the deeper layers of the SC. This labeling covered the entire mediolateral extent of the SC, but, in keeping with the pattern of retrograde labeling following microsphere injections in the SC, was more restricted rostrocaudally. No systematic changes were observed with age. The stability of the nBIC-SC projection over this period suggests that developmental changes in auditory spatial tuning involve other processes, rather than a gross refinement of the projection from the nBIC.     

药物治疗与合并认知行为治疗对强迫症疗效的比较

目的探讨认知行为心理治疗(CBT)在强迫症(OCD)患者各亚型治疗中的有效性和规律性。方法本研究为临床对照研究。符合入组标准的强迫症患者按患者自愿原则分为两组,治疗观察3、6、12个月。疗效评定分别运用Yale-Brown强迫量表,自拟的自评好转程度量表和临床疗效评定。结果认知行为心理治疗合并药物治疗组31例,临床有效率70.9%,其中治愈率1.8%。单纯药物治疗组24例,临床有效率33.3%。Yale-Brown强迫量表和自评量表得分在6个月和12个月两组有显著差异(P<0.05)。其中强迫症亚型(怕脏型、反复检查型和反复担心型)的疗效比较,怕脏型在治疗3个月末两组间自评量表评分有显著性差异(P<0.05);反复担心型在治疗6个月末两组间Yale-Brown强迫量表总分有显著性差异(P<0.05);反复检查型两组间无统计学差异。结论认知行为心理治疗合并药物治疗强迫症的疗效明显优于单纯药物治疗。强迫症的亚型在治疗中的有效性次序为:反复担心型>怕脏型>反复检查型。     

Origins of the sympathetic innervation of the cervical end of the uterus in the rat

A retrograde neuronal tracer (Fast Blue) was injected in the cervical end of the uterine horn of virgin rats. The majority of the retrogradely labeled post-ganglionic sympathetic neurons were found in the sympathetic chain (74%). The superior mesenteric ganglia, inferior mesenteric ganglia and suprarenal ganglia accounted for 22, 3 and <1%, respectively. The distribution of neurons in the sympathetic chain labeled from the uterus resembles that described for other pelvic organs.     

Sex differences in subregions of the medial nucleus of the amygdala and the bed nucleus of the stria terminalis of the rat

Sex differences are described in subregions of two nuclei of the rat brain: the medical nucleus of the amygdala (MA) and the bed nucleus of the stria terminalis (BNST). The volume of the posterodorsal region of the medial nucleus of the amygdala (MApd) is approximately 85% greater and the volume of the encapsulated region of the bed nucleus of the stria terminalis (BNSTenc) is approximately 97% greater in males than in females. The MApd and BNSTenc are distinct subregions of the MA and BNST. They exhibit intense uptake of gonadal hormones and are anatomically connected to each other and to other sexually dimorphic nuclei. The MA and BNST in general are involved in regulation of several sexually dimorphic functions, including aggression, sexual behavior, gonadotropin secretion and integration of olfactory information. Precise localization of sex differences in subregions of the MA and BNST, such as the MApd and BNSTenc, may facilitate understanding of the neural basis of such functions.     

Function of the ventrolateral medulla in the control of the circulation

The CNS control of the cardiovascular system involves the coordination of a series of complex neural mechanisms which integrate afferent information from a variety of peripheral receptors and produce control signals to effector organs for appropriate physiological responses. Although it is generally thought that these control signals are generated by a network of neural circuits that are widely distributed in the CNS, over the last two decades a considerable body of experimental evidence has accumulated suggesting that several of these circuits involve neurons found on or near the ventral surface of the medulla oblongata. Neurons in the VLM have been shown to be involved in the maintenance of vasomotor tone, in baroreceptor and chemoreceptor (central and peripheral) reflex mechanisms, in mediating the CIR and somatosympathetic reflexes and in the control of the secretion of vasopressin. These physiological functions of VLM neurons have been supported by neuroanatomical and electrophysiological studies demonstrating direct connections with a number of central structures previously implicated in the control of the circulation, including the IML, the site of origin of sympathetic preganglionic axons, and the SON and PVH, the site of origin of neurohypophyseal projecting axons containing AVP.Considerable suggestive evidence has also been obtained regarding the chemical messengers involved in transmitting information from VLM neurons to other central structures. There have been developments suggesting a role for monoamines and neuropeptides in mediating the neural and humoral control of SAP by neurons in the VLM.This review presents a synthesis of the literature suggesting a main role for VLM neurons in the control of the circulation.     

Mechanisms of the suppression of the nociceptive reflex of the opening of the mouth during stimulation of the structures of the limbic brain

The comparative effectiveness of the inhibitory influence of tetanic stimulation of hypothalamus, amygdala and limbic cortex on EMG-response of m. digastricus evoked by electrical stimulation of tooth pulp nociceptive afferents was studied in cats anesthetized with a mixture of chloralose and nembutal. It was found that inhibition of the EMG-component of the jaw-opening reflex is most pronounced in case of stimulation of medial and lateral region of the hypothalamus, the inhibitory effect of central and medial nuclei of the amygdala is less pronounced and the effect of the limbic cortex is the weakest. It was shown that the mechanism of the antinociceptive effect of tetanic stimulation of the hypothalamus is not related to the concomitant increase of the blood pressure. After stabilization of the blood pressure the suppressive effect of the hypothalamus remains without changes, that points out to a direct, primary, not baro-afferent mechanism of the inhibition of the activity of nociceptive neurons of the trigeminal sensory nuclei. Noradrenaline, injected intravenously, induced a large increase of the blood pressure accompanied by a pronounced inhibition of the pain reflex. Angiotensin causes the same degree of blood pressure elevation without changes in the amplitude of the EMG-response of the pain reflex. Hypothalamic and noradrenergic mechanisms for control of pain sensitivity are discussed.     

Sexual pheromones and the evolution of the reward system of the brain: the chemosensory function of the amygdala

The amygdala of all tetrapod vertebrates receives direct projections from the main and accessory olfactory bulbs, and the strong similarities in the organization of these projections suggest that they have undergone a very conservative evolution. However, current ideas about the function of the amygdala do not pay sufficient attention to its chemosensory role, but only view it as the core of the emotional brain. In this study, we propose that both roles of the amygdala are intimately linked since the amygdala is actually involved in mediating emotional responses to chemical signals. The amygdala is the only structure in the brain receiving pheromonal information directly from the accessory olfactory bulbs and we have shown in mice that males emit sexual pheromones that are innately attractive for females. In fact, sexual pheromones can be used as unconditioned stimuli to induce a conditioned attraction to previously neutral odorants as well as a conditioned place preference. Therefore, sexual pheromones should be regarded as natural reinforcers. Behavioural and pharmacological studies (reviewed here) have shown that the females' innate preference for sexual pheromones is not affected by lesions of the dopaminergic cells of the ventral tegmental area, and that the systemic administration of dopamine antagonists do not alter neither the attraction nor the reinforcing effects of these pheromones. Anatomical studies have shown that the vomeronasal amygdala gives rise to important projections to the olfactory tubercle and the islands of Calleja, suggesting that these amygdalo-striatal pathways might be involved in the reinforcing value of sexual pheromones.     

Topographical organization of the motoneuron pools that innervate the muscles of the pinna of the cat

The topographical organization of the 22 motoneuron pools that innervate the pinna muscles of the cat was examined by injecting the B-subunit of cholera toxin conjugated to horseradish peroxidase into individual muscles. All 22 pools are found in the facial nucleus, organized as rostro-caudally oriented columns, and arranged according to the action of the muscles they innervate. Pools innervating muscles that pull the pinna dorsally are located in the dorsal two thirds of the medio-dorsal subdivision, and those innervating muscles that pull the pinna ventrally are located in the ventral one half of the nucleus. Motoneurons innervating muscles that pull the pinna cranially are located laterally, those that pull the pinna caudally are located medio-ventrally, and those that change the shape of the pinna are located along the entire dorso-ventral extent in the center of the medio-dorsal subdivision. This topographical layout is consistent with the somatotopic organization of the entire facial nucleus as demonstrated in a variety of species. © 1995 Wiley-Liss, Inc.     

A contribution to the study of the architecture of the autonomic nervous system of the digestive tract of the rat

Summary The distribution of aminergic and non-aminergic nerve fibres to the different constituents of the wall of the digestive tract in various regions is described. Aminergic fibres synapse with all nervous perikarya. Densely interlacing networks of nerve fibres are found in both layers of the tunica muscularis and in the lamina muscularis mucosae. A finely meshed plexus is observed in relation to the wall of the blood vessels in the wall of the gut. There are many fibres connecting the muscular and the vascular plexus. No nerve fibres have been observed in direct relation to the epithelium.The functional implications of these findings are discussed.     

An electrophysiological characterization of the projection from the central nucleus of the amygdala to the periaqueductal gray of the rat: the role of opioid receptors

The midbrain periaqueductal gray (PAG) and the central nucleus of the amygdala (CNA) are both known to be involved in fear and anxiety, analgesia, vocalization, cardiovascular and respiratory changes, and freezing. Anatomical studies have shown that a connection between these two regions exists but little is known about the physiology or the neurochemical constituents of this pathway. The goals of this study were to characterize the projection from the CNA to the PAG using electrophysiological techniques and to determine whether μ- and/or δ-opioid receptors, which play a large role in a majority of the functions of the PAG, are involved in this pathway. Of the 38 PAG cells tested with single shock stimulation of the CNA, 44% responded; of those, 46% were excited and 54% were inhibited. The latency to onset of response for the inhibitory cells (12.71 ± 6.61 ms) was shorter than that of the excitatory cells (22.33 ± 4.04 ms). Forty-six percent of the 129 PAG cells tested with train electrical stimulation of the CNA responded; 44% were excited and 56% were inhibited. Chemical stimulation of the CNA (10 mMd,l-homocysteic acid) produced similar results; 48% (62/128) of PAG cells responded; 45% of cells were excited and 55% were inhibited. The baseline firing rate of the inhibitory cells was significantly higher compared to the excitatory cells. Chemical stimulation of the CNA produced an increase in blood pressure in 12 animals, a decrease in two animals, and had no effect on the blood pressure of 68 animals. The blood pressure changes ranged between 8.5 and 26.3 mmHg with a mean of 16.2 ± 2.2 mmHg. The effect of naloxone (given either on site in the PAG or systemically) on the response to CNA stimulation was tested in 21 cells. Twenty-five percent of the excitatory cells (2/8) and 77% (10/13) of the inhibitory cells were blocked by naloxone with the majority of the blocked cells located in the ventrolateral PAG. It is concluded that: (1) Approximately 50% of cells in the lateral and ventrolateral columns of the PAG respond to CNA stimulation; (2) the inhibitory response is mediated by a faster conducting or a more direct pathway than the pathway that mediates the excitatory response; (3) neurons that are inhibited by CNA stimulation have a significantly higher baseline firing rate than neurons that are excited, suggesting that they may be tonically active interneurons; and (4) at least one link in the CNA-PAG pathway utilizes μ- or δ-opioid receptors.     

Development of the cochlear innervation of the dorsal cochlear nucleus of the hamster

The development of cochlear fibers and terminals in the dorsal cochlear nucleus of the hamster was studied with light and electron microscopic techniques. Like the dorsal cochlear nucleus of most other mammals, the dorsal cochlear nucleus of the adult hamster is a laminated structure. Three distinct layers can be identified in cresyl-violet-stained sections: the molecular layer, the fusiform cell layer, and the deep layer. The deep layer consists of a superficial zone, free of large cell bodies, and a deep zone which contains the somas of giant cells. Horseradish peroxidase and degeneration studies reveal that the cochlear fibers ramify throughout the deep and fusiform cell layers of the adult hamster but do not enter the molecular layer. In the electron microscope, three types of terminals that contact the fusiform and the giant cells can be distinguished. Only one type of terminal (type LR) degenerates after cochlear ablation and is, therefore, thought to be of cochlear origin. Type LR terminals are found throughout the deep and fusiform cell layers and contact the somas of giant and fusiform cells, as well as their intermingled dendrites in the deep layer. In Golgi-impregnated material, cochlear fibers are not found in the dorsal cochlear nucleus of the neonatal hamster, although they have entered the ventral cochlear nucleus. Ingrowth of cochlear fibers into the dorsal cochlear nucleus occurs over the first postnatal week and one-half. A spatial gradient is evident during the ingrowth of the fibers in that they invade the dorsomedial parts of the dorsal cochlear nucleus before they invade the ventrolateral parts. In all parts of the nucleus, the fibers enter the deepest layer and grow progressively more superficially. In the electron microscope, the first appearance of type LR terminals at each depth lags behind the ingrowth of the fibers by about two days. In hamsters, fibers from the basal turns of the cochlea terminate in the dorsomedial dorsal cochlear nucleus, while fibers from the apical turns terminate in the ventrolateral dorsal cochlear nucleus (DCN). The dorsomedial to ventrolateral gradient in the ingrowth of the cochlear fibers into the DCN indicates that the fibers from the basal turn are the first to arrive. Several components of the mammalian cochlea have been shown to mature at the base of the cochlea before they mature at the apex. The present study suggests that maturation gradients in the cochlear nucleus parallel those observed in the cochlea.     

Effect of stimulation of the superior colliculi of the tectum mesencephali on the motor neurons of the neck muscles of the cat

Postsynaptic potentials evoked by stimulation of three points of the superior colliculus in motoneurons of neck muscles were studied in experiments on cats under chloralosenembutal anesthesia. Stimulation of ipsilateral superior colliculus evoked EPSP with latencies ranging from 1.5 to 3.5 ms in 49 motoneurons. Stimulation of contralateral superior colliculus evoked EPSP with latencies ranging from 1.5 to 3.0 ms in 63 motoneurons and IPSP with latencies ranging from 2.6 to 5.0 ms in 10 motoneurons. It is suggested that the recorded postsynaptic potentials are mono- and disynaptic.     

Effect of the richness of the environment on the cat visual cortex

In a recent study of the cat visual cortex, it was shown that there are interindividual differences in the numerical density (Nv) of symmetrical synapses associated with flat vesicles (FS synapses) but not of asymmetrical synapses associated with round vesicles (RA synapses). Since many of the environment-sensitive properties of visual cortex neurons are GABA-dependent, it was suggested that the interindividual differences in FS synapses might be due to environmental factors. To verify this possibility we estimated the Nv of both types of synapses in two groups of six cats, paired by litter and by sex, and raised either in isolation or in a colony from the time of weaning to the age of 8 months. We also measured the Nv of neurons and the thickness of the cortex and made some gross anatomical measurements. The brains of animals raised in the enriched environment are 7% heavier, and their total body weight is 10% greater: The brain-to-body-weight ratio remains unchanged. The total length of the brain is not affected, but the length and width of the cerebral hemispheres are each 5% greater in the enriched cats. As in comparable rat studies, the thickness of the cortex is 4% greater, but in the present study this difference is not significant. The numerical density of neurons is diminished by 17% in enriched animals. This is probably due to a wider separation of neuronal cell bodies in a larger cortical volume, rather than to a loss of neurons. There are no significant changes in the numerical density of RA synapses between the two milieux, but there are nearly twice as many FS synapses per mm3 of tissue in the impoverished cortex. The coefficient of variation of FS synapses, which in the previous study was on the order of 30%, has been reduced to 10% and 7% in enriched and impoverished cats, respectively. We conclude that environmental conditions can lead to selective interindividual differences in the Nv of FS synapses, as seen in our previous study of animals whose rearing conditions were not controlled. The average diameter of RA synaptic profiles is not affected by the environment but FS synapses are 25% wider in the enriched animals. Because of the smaller neuronal Nv in enriched animals, there are, in fact, 18% more RA synapses and 34% fewer FS synapses per neuron in the enriched condition.(ABSTRACT TRUNCATED AT 400 WORDS)     

Innervation of the digit on the forepaw of the raccoon

The innervation of the digits on the raccoon forepaw was examined by using immunochemistry for protein gene product 9.5, calcitonin-gene related peptide, substance P, neuropeptide-Y, tyrosine hydroxylase, and neurofilament protein. The larger-caliber axons in the ventral glabrous skin terminate as Pacinian corpuscles deep in the dermis, small corpuscles and Merkel endings around the base of dermal papillae, and Merkel endings on rete pegs in dermal papillae. Extensive fine-caliber innervation terminates in the epidermis and on the microvasculature. The innervation is more dense in the distal than in the proximal volar pads. Pacinian endings are also concentrated in the transverse crease separating the distal and proximal pads. In the dorsal hairy skin, hair follicles are well innervated with piloneural complexes. Merkel innervation is located under slight epidermal elevations and in some large Merkel rete pegs located at the apex of transverse skin folds just proximal to the claw. No cutaneous Ruffini corpuscles were found anywhere on the digit. The claw is affiliated with dense medial and lateral beds of Pacinian endings, bouquets of highly branched Ruffini-like endings at the transition from the distal phalanx and unmyelinated innervation in the skin around the perimeter. Encapsulated endings are located at the lateral edge of the articular surface of the distal phalanx. Extensive fine-caliber innervation is affiliated with sweat glands and with the vasculature and is especially dense at presumptive arteriovenous sphincters. Virtually all of the sweat gland and vascular innervation is peptidergic, whereas most of the unmyelinated epidermal innervation is nonpeptidergic.     

Organization of projections from the mediodorsal nucleus of the thalamus to the basolateral complex of the amygdala in the rat

Mediodorsal thalamic (MD) projections to the basolateral amygdaloid complex of the rat were investigated with the anterograde neuronal tracer, Phaseolus vulgaris-leucoagglutinin. Iontophoretic injections were made in distinct subdivisions of the rostral and caudal part of the MD. Both the medial and lateral division of the MD showed a projection to the basolateral complex and there appears to be a topographical organization of the innervation in the rostrocaudal direction: the rostral and caudal part of the MD project to respectively the mid-rostrocaudal and rostral part of the basolateral complex.     

Study of the effects of flexion on the position of the conus medullaris

BACKGROUND: Previous anatomic studies have shown the conus medullaris to terminate between T12 and L1 vertebral levels in adults with normal spinal anatomy. Prior anatomic and radiographic studies of conus position with flexion and extension of the spine have had conflicting results. We performed a cadaveric study with direct visualization of the conus during flexion and extension to further study this question and potentially determine if flexion and extension of the spine during magnetic resonance imaging may prove to be a diagnostic tool in such pathologies as occult tethered cord syndrome. MATERIALS AND METHODS: We performed T12 to L3 laminectomies in five fresh adult cadavers and exposed the conus and cauda equina. Cadavers were fully flexed at the waist and neck and the conus position observed. RESULTS: In all specimens, the conus terminated between T12 and L1 in the prone position. During flexion, the conus position remained stable with no ascent. However, flexion produced stretching and medial displacement of the cauda equina. CONCLUSIONS: Flexion of the spine does not cause the conus medullaris to change position in fresh human cadavers; however, flexion does cause the cauda equina to stretch and displace medially over the conus. Therefore, it is unlikely that the conus would change position during spine flexion during imaging or procedures such as lumbar puncture.     

Representation of the cornea in the brain stem of the rat

Single units in the rat's brain stem that responded to tactile stimulation of the cornea were found mainly in a region on the ventromedial border of the trigeminal nuclei. This region included adjacent parts of the reticular formation and extended from the principal sensory trigeminal nucleus to caudal portions of nucleus caudalis of the spinal trigeminal complex. One class of units responded to light punctate stimuli and small electric currents; a second class had higher thresholds for both kinds of stimulation. The former units generally had shorter response latencies and larger corneal receptive fields than the latter units, although distributions for the two kinds of units overlapped appreciably for both properties. High-threshold and low-threshold units were found at all rostrocaudal levels and were not distributed differentially in the trigeminal nuclei or in the reticular formation. Units in a third class were scattered in more medial parts of the reticular formation. They tended to have longer response latencies than trigeminal border units, but similar response thresholds. Many units, including those with high thresholds, were very senstive to moving stimuli, including movements of the eyelids. Very few units responded to thermal stimulation of the cornea.     

Quantitative analysis of the neuronal population of the red nucleus of the cat

There is strong evidence in the literature for a correlation between the two parts of the red nucleus, magnocellular and parvocellular, and different functions. Unfortunately in the cat, the species most studied both physiologically and anatomically, there are no morphological criteria distinguishing the two portions. With quantitative techniques applied to Nissl preparations the neuronal population of the Red Nucleus has been studied in serial sections along the rostrocaudal axis of the mesencephalon of the cat. Statistical analysis of the data revealed a horizontal plane dividing the two portions of the nucleus with a high statistical significance level. This plane lies between the caudal two-thirds and the rostral third of the nucleus. Although in the model two portions can be distinguished, it is not possible to assign to either a single type of neuron, whether or considered in terms of shape or size.

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Sommario Vi è buona evidenza in letteratura che la presenza di due componenti, magno-e parvo-cellulare, nel Nucleo Rosso dei mammiferi è correlabile con parti funzionalmente differenti. Sfortunatamente nel gatto, la specie maggiormente studiata sia fisiologicamente che anatomicamente, mancano criteri morfologici di distinzione fra le due parti. Applicando tecniche quantitative su preparati Nissl, è stata studiata la popolazione cellulare del Nucleo Rosso in sezioni seriate lungo l'asse rostro-caudale del mesencefalo. Mediante una analisi statistico-matematica dei dati raccolti si è potuto dimostrare con un ottimo livello di significatività un piano orizzontale di divisione in due parti del nucleo. Questo piano risulta posto fra i due terzi caudali ed il terzo rostrale del nucleo. Pur riconoscendo due parti distinte nel modello ottenuto, non è però possibile assegnare a ciascuna di esse un tipo esclusivo di elemento cellulare, sia considerando la forma sia considerando la dimensione dei neuroni.

     

Lineage-based analysis of the development of the central complex of the Drosophila brain

Most neurons of the central complex belong to 10 secondary (larvally produced) lineages. In the late larva, undifferentiated axon tracts of these lineages form a primordium in which all of the compartments of the central complex can be recognized as discrete entities. Four posterior lineages (DPMm1, DPMpm1, DPMpm2, and CM4) generate the classes of small-field neurons that interconnect the protocerebral bridge, fan-shaped body, noduli, and ellipsoid body. Three lineages located in the anterior brain, DALv2, BAmv1, and DALcl2, form the large-field neurons of the ellipsoid body and fan-shaped body, respectively. These lineages provide an input channel from the optic tubercle and connect the central complex with adjacent anterior brain compartments. Three lineages in the posterior cortex, CM3, CP2, and DPMpl2, connect the posterior brain neuropil with specific layers of the fan-shaped body. Even though all of the compartments of the central complex are prefigured in the late larval brain by the axon tracts of the above-mentioned lineages, the neuropil differentiates during the first 2 days of the pupal period when terminal branches and synapses of secondary neurons are formed. During this phase the initially straight horizontal layers of the central complex bend in the frontal plane, which produces the characteristic shape of the fan-shaped and ellipsoid body. Our analysis provides a comprehensive picture of the lineages that form the central complex, and will facilitate future studies that address the structure or function of the central complex at the single cell level.