The influence of damage to the septum pellucidum on the effects of electrical stimulation of the hypothalamus in rabbits]

In chronic experiments the influences of septal lesions on the behavioural emotional effects of electrical stimulation of various hypothalamic nuclei were investigated. The total ablation of the septum caused irreversible increase of the lateral hypothalamus self-stimulation and reversal of the negative emotional responses (escape--avoidance) to the medial hypothalamus stimulation into the positive self-stimulation behaviour. When the septal ablation was only partial, involving mainly the medial nucleus, effects were weaker and lasted only 2-3 days after the surgery. The role of the septum in the septohippocampal behavioural inhibition system (J. Gray) is discussed.     

ACTH fragments in compensation mechanisms of self-stimulation after ablation of the septal region in rabbits

Unilateral lesions of septal region, which partially included commissure anterior, commissural nuclei, fornix and apical parts of medial and lateral preoptic area, inhibited hypothalamic self-stimulation in rabbits. Intraventricular injection of ACTH (4-10) and ACTH (1-24) evoked the restoration of self-stimulation behaviour.     

Distribution of neuropeptide Y-like immunoreactive fibers in the cat thalamus

Neuropeptide Y-like immunoreactivity was studied in the thalamus of the cat using an indirect immunoperoxidase method. The densest network of immunoreactive fibers was observed in the nucleus (n.) paraventricularis anterior. In the anterior, intralaminar and midline thalamic nuclei, as well as in the n. geniculatum medialis, n. geniculatum lateralis, n. habenularis lateralis, n. medialis dorsalis, n. lateralis posterior and n. pulvinar a low density of neuropeptide Y-like immunoreactive fibers was observed. Neuropeptide Y-like fibers were totally absent in the n. ventralis lateralis, n. ventralis medialis, n. ventralis postero-medialis and n. ventralis postero-lateralis. In addition, neuropeptide Y-like perikarya were found in the n. parafascicularis, n. suprageniculatus, n. geniculatum lateralis ventralis, n. medialis dorsalis and n. lateralis posterior.     

Projections to the midbrain tectum in Salamandra salamandra L.

Following unilateral iontophoretic application of HRP into the optic tectum of Salamandra salamandra, retrogradely HRP-filled cells were found bilaterally in the pretectum, tegmentum isthmi, the reticular formation, pars medialis, and in the nucleus vestibularis magnocellularis. The area octavo-lateralis projects only to the caudal part of the tectum. Ipsilateral projections were noted from the dorsal gray columns of the cervical spinal cord, the dorsal tegmentum, the thalamus dorsalis pars medialis, thalamus dorsalis, pars anterior (to the rostral one-third of the tectum), the thalamus ventralis (in its entire rostro-caudal extent), and the preoptico-hypothalamic complex. Retrogradely filled cells were identified in deeper layers of the contralateral tectum. There are two telencephalic nuclei projecting ipsilaterally to the tectum via the lateral forebrain: the ventral part of the lateral pallium, and the posterior strioamygdalar complex.     

Changes in RNA content in neurons of the superior olivary complex during monaural and binaural stimulation

The character of binaural competitive connections at the level of the superior olive was investigated cytospectrophotometrically in cats. As a result of monaural stimulation for 2 h or binaural stimulation for 1.5 h by rhythmic noise signal the RNA content in the neurons of the ipsilateral and contralateral medial and lateral nuclei increased significantly. The volume of functioning neurons in the nuclei studied either increased or remained the same as in the control. The increase in the RNA content in neurons of both the ipsilateral and contralateral medial and lateral nuclei suggests a uniform distribution of binaurally converging connections on the neurons of these nuclei. The results also suggest that the accumulation of cytoplasmic RNA takes place in response not only to excitation, but also to inhibition.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 10, No. 1, pp. 67–74, January–February, 1978.     

Distribution of parvalbumin-immunoreactivity in the rat thalamus using a monoclonal antibody

1. The distribution of parvalbumin cell bodies and fibers in the thalamus of the rat was studied using a monoclonal antibody and the avidin-biotin-peroxidase method. The densest clusters of immunoreactive perikarya were observed in the nuclei ventralis posterior, reticularis, ventralis anterior and zona incerta, whereas the nuclei habenularis lateralis, lateralis posterior, lateralis, centralis lateralis and ventralis lateralis had the lowest density. In the nucleus geniculatum laterale ventralis, the density of parvalbumin cell bodies was intermediate. In all these thalamic nuclei, small, round or fusiform immunoreactive cells with short immunolabeled dendritic processes were observed. 2. The densest network of immunoreactive fibers was observed in the nuclei geniculatum laterale ventralis, reticularis and zona incerta. The nuclei geniculatum laterale dorsalis, ventralis posterior, medialis ventralis, ventralis anterior, anterior ventralis, anterior dorsalis and rhomboidens contained a moderate number of parvalbumin fibers, whereas the nuclei lateralis posterior, habenularis lateralis, parataenialis, centrum medianum, lateralis, centralis lateralis, ventralis lateralis, medialis dorsalis, anterior medialis, ventralis medialis and lateralis anterior had the lowest density of immunoreactive fibers. In addition, a large number of immunoreactive fibers was found in the lemniscus medialis and a scarce number in the stria medullaris. 3. No immunoreactive structure was observed in the nuclei habenularis medialis, paraventricularis, reuniens and geniculatum mediale. 4. Thus, perikarya and fibers containing parvalbumin are widely distributed throughout the thalamus of the rat, suggesting that parvalbumin might play a role, directly or indirectly, in limbic, visual and somatosensory mechanisms.     

Organization of the telencephalon in the channel catfish,Ictalurus punctatus

The cytoarchitectonics of the telencephalon of the channel catfish, Ictalurus punctatus, are described as a basis for experimental analysis of telencephalic afferents and efferents. The olfactory bulb comprises: (1) an outer layer of olfactory nerve fibers, (2) a glomerular layer, (3) an external cell layer, (4) an inner fiber layer, and (5) an internal cell layer. The telencephalic hemispheres comprise the areas ventralis and dorsalis telencephali. The area ventralis consists of: (1) a precommissural, periventricular zone including nucleus 'nother (Vn), the ventral nucleus (Vv), and the dorsal nucleus (Vd); (2) a precommissural, migrated zone of central (Vc) and lateral (VI) nuclei; (3) a supracommissural nucleus (Vs); (4) a caudal commissural zone of postcommissural (Vp) and intermediate (Vi) nuclei; and (5) a preoptic area (PP). The area dorsalis comprises: (1) medial (DM), (2) dorsal (Dd), (3) lateral [DL, containing dorsal (DLd), ventral (DLv), and posterior (DLp) regions], (4) posterior (DP), and (5) central (DC-1, -2, -3) areas. Nucleus taeniae (NT) is transitional between areas dorsalis and ventralis.     

Ascending and descending projections to the inferior colliculus in the rat

The ascending and descending projections to the central nucleus of the inferior colliculus (IC) were studied with the aid of retrograde transport of horseradish peroxidase (HRP). HRP-labelled cells were found in contralateral cochlear nuclei, where the majority of different cell types was stained. Few labelled cells were observed in the ipsilateral cochlear nuclei. HRP-positive neurones were found in all nuclei of the superior olivary complex on the ipsilateral side with the exception of the medial nucleus of the trapezoid body, which was never labelled either ipsilaterally or contralaterally. The largest concentration of HRP-labelled cells was usually observed in the ipsilateral superior olivary nucleus. Smaller numbers of labelled cells were present in contralateral nuclei of the superior olivary complex. Massive projections to the inferior colliculus were found from the contralateral and ipsilateral dorsal nucleus of the lateral lemniscus and ipsilateral ventral nucleus of the lateral lemniscus. Many neurones of the central and external nuclei of the contralateral inferior colliculus were labelled with HRP. Topographic organisation of the pathways ascending to the colliculus was expressed in the cochlear nuclei, lateral superior olivary nucleus and in the dorsal nucleus of the lateral lemniscus. HRP--positive cells were found in layer V of the ipsilateral auditory cortex, however, the evidence for topographic organisation was lacking.     

Telencephalic sources of the afferents of the main olfactory bulb in the frog Rana temporaria

Following horseradish peroxidase iontophoretic application into the main olfactory bulb (MOB) retrograde neuronal labeling was examined in the telencephalon in the frog. Labeled neurons, the sources of the MOB afferents are found in the mitral cell layer of the contralateral MOB, pallial and some subpallial areas. Very heavy labeling is observed in the pars ventralis of the lateral pallium, and to a lesser extent in the medial pallium, pars dorsalis of the lateral pallium and in the dorsal pallium. In subpallium labeled neurons are found in the eminentia postolfactoria, the rostral part of the medial septal nucleus, and in the nucleus of the ventro-medial telencephalic wall, which is probably homologous to the nucleus of the diagonal band (Broca) of mammals. No labelled neurons were found in the caudal portion of the MOB granular layer, usually referred to as the anterior olfactory nucleus. The arrangement of the MOB centrifugal innervation in amphibians is discussed in comparison with that in mammals.     

Commissural connections mediate inhibition for the computation of interaural level difference in the barn owl

Summary In the barn owl (Tyto alba), the posterior nucleus of the ventral lateral lemniscus (VLVp) is the first site of binaural convergence in the pathway that processes interaural level difference (ILD), an important sound-localization cue. The neurons of VLVp are sensitive to ILD because of an excitatory input from the contralateral ear and an inhibitory input from the ipsilateral ear. A previously described projection from the contralateral cochlear nucleus, can account for the excitation. The present study addresses the source of the inhibitory input.We demonstrate with standard axonal transport methods that the left and right VLVps are interconnected via fibers of the commissure of Probst. We further show that the anesthetization of one VLVp renders ineffective the inhibition that is normally evoked by stimulation of the ipsilateral ear. Thus, one cochlear nucleus (driven by the ipsilateral ear) appears to provide inhibition to the ipsilateral VLVp by exciting commissurally-projecting inhibitory neurons in the contralateral VLVp.Abbreviations ABL average binaural level - CP commissure of Probst - DNLL dorsal nucleus of the lateral lemniscus - IC inferior colliculus - ILD interaural level difference - IPc nucleus isthmi, pars parvocellularis - ITD interaural time difference - LSO lateral superior olive - MNTB medial nucleus of the trapezoid body - NA nucleus angularis - SL nucleus semilunaris - VLVa nucleus ventralis lemnisci lateralis, pars anterior - VLVp nucleus ventralis lemnisci lateralis, pars posterior     

Neuropeptides and monoamines in the carp (Cyprinus carpio) pretectum: An immunocytochemical study

The distribution of neurotensin, neurokinin A, dynorphin A, galanin, somatostatin-28 (1-12), neuropeptide Y, vasoactive intestinal polypeptide, gastrin-releasing peptide, gamma-melanocyte stimulating hormone, alpha-neo-endorphin, angiotensin H, cholecystokinin-8, serotonin and tyrosine hydroxylase has been studied in the pretectal nuclei of the Cyprinus carpio: nuclei pretectalis superficialis parvicellularis and magnocellularis, pretectalis centralis, pretectalis, and pretectalis periventricularis dorsalis and ventralis using an indirect immunoperoxidase technique. We have found neuropeptide Y and serotonin immunoreactive fibres in all pretectal nuclei, whereas gastrin-releasing peptide immunoreactive fibres were visualized in the nuclei pretectalis superficialis parvicellularis and magnocellularis, pretectalis centralis. pretectalis and pretectalis periventricularis dorsalis; neurokinin A immunoreactive fibres in the nuclei pretectalis superficialis parvicellularis and magnocellularis and pretectalis periventricularis dorsalis; galanin immunoreactive fibres in the nuclei pretectalis superficialis parvicellularis, pretectalis centralis and pretectalis periventricularis dorsalis; and neurotensin immunoreactive fibres in the nucleus pretectalis periventricularis dorsalis. Additionally, immunoreactive cell bodies containing neuropeptide Y were observed in the nuclei pretectalis superficialis parvicellularis and pretectalis periventricularis dorsalis, and serotonin and tyrosine hydroxylase cell bodies were found in the nuclei pretectalis periventricularis dorsalis and ventralis respectively. The presence of the neuroactive substances found in the carp pretectal nuclei suggest that they might be involved in the regulation of certain functions within the visual system.     

Age-related changes in central nervous system enkephalins and substance P

Concentrations of substance P and met- and leu-enkephalins were measured by radioimmunoassay in discrete rat brain nuclei of young (4–5 months) and old (24–26 months) rats. The substance P content of n. anterior (hypothalami), n. ventromedialis, n. premamillaris ventralis, n. interstitialis striae terminalis, n. entopeduncularis and n. dorsalis raphes is reduced in old rats. The met-enkephalin content is decreased in n. suprachiasmaticus, n. arcuatus and n. premamillaris ventralis while the leu-enkephalin content of n. preopticus medialis, n. suprachiasmaticus, n. paraventricularis, n. ventromedialis and n. premamillaris ventralis is decreased in old rats.     

Central projections of the nervus terminalis in the bichir,Polypterus palmas

Summary Central pathways of the nervus terminalis (n.t.) in the bichir, Polypterus palmas, were studied with the use of tracing techniques. After application of horseradish peroxidase to the unilateral olfactory mucosa labeled n.t. fibers were traced in seven distinct bundles through the subpallium. Projection areas are found in the precommissural ventral nucleus of the area ventralis telencephali ipsilaterally, the anterior commissure and commissural parts of the periventricular preoptic nucleus bilaterally; few n.t.-fibers cross via the anterior commissure to the contralateral side; no fibers were observed to turn rostrally to the contralateral olfactory bulb. Major targets of the n.t. include a restricted ventral part of the periventricular preoptic nucleus at the level of the optic chiasma bilaterally, and the periventricular nuclei located between the thalamic nuclei and the hypothalamus bilaterally. N.t. fibers continue their course through the ipsilateral hypothalamus and are traced as far as the mesencephalic tegmentum ipsilaterally. N.t. terminations are found consistently within the boundaries of periventricular cell nuclei, suggesting axosomatic synaptic contacts. We propose a differentiation of the n.t. ganglion cells into a distal (mucosal) and proximal (bulbar) type regarding the peripheral cell processes. Our findings are compared with those of other reports on the n.t. system.     

Met-enkephalin restores self-stimulation behavior in rabbits after destruction of the hypothalamic nuclei]

Contralateral lesions of ventromedial and lateral hypothalamic nuclei inhibited hypothalamic self-stimulation in rabbits. Intracerebroventricular injection of metenkephalin evoked the restoration of self-stimulation behavior.     

Pattern of afferents to the lateral septum in the guinea pig

Summary The septal region represents an important telencephalic center integrating neuronal activity of cortical areas with autonomous processes. To support the functional analysis of this brain area in the guinea pig, the afferent connections to the lateral septal nucleus were investigated by the use of iontophoretically applied horseradish peroxidase (HRP). Retrogradely labeled perikarya were located in telencephalic, diencephalic, mesencephalic and metencephalic sites. The subnuclei of the lateral septum (pars dorsalis, intermedia, ventralis, posterior) receive afferents from the (i) medial septal nucleus, diagonal band of Broca (pars horizontalis and pars ventralis), and the principal nucleus of the stria terminalis, the hippocampus, and amygdala (nucleus medialis); (ii) the medial habenular nucleus, and the para- (peri-) ventricular, parataenial and reuniens nuclei of the thalamus; the anterior, lateral and posterior hypothalamic areas in particular, the medial and lateral preoptic, suprachiasmatic, periventricular, paraventricular, arcuate, premammillary, and supramammillary nuclei; (iii) the periaquaeductal grey, ventral tegmental area, nucleus interfascicularis, nucleus reticularis linearis, central linear nucleus, interpeduncular nucleus; (iv) dorsal and medial raphe complex, and locus coeruleus. Each subnucleus of the lateral septum displays an individual, differing pattern of afferents from the above-described regions. Based on a double-labeling method, the vasopressinergic and serotonergic afferents to the lateral septum were found to originate in the nucleus paraventricularis hypothalami and the raphe nuclei, respectively.Abbreviations ARC arcuate nucleus - BNST bed nucleus of the stria terminalis - CL central linear nucleus - DBBh diagonal band of Broca (pars horizontalis) - DBBv diagonal band of Broca (pars ventralis) - DR dorsal raphe nucleus - HC hippocampus - IF interfascicular nucleus - IP interpeduncular nucleus - LC locus coeruleus - LDT laterodorsal tegmental nucleus - LHA lateral hypothalamic area - LPO lateral preoptic area - LSN lateral septal nucleus - MA medial amygdaloid nucleus - MH medial habenular nucleus - MPO medial preoptic region - MR medial raphe nucleus - MSN medial septal nucleus - PAG periaquaeductal grey - PEN periventricular nucleus - PHA posterior hypothalamic area - PMd premammillary region (pars dorsalis) - PMv premammillary region (pars ventralis) - PT parataenial nucleus - PVN paraventricular hypothalamic nucleus - PVT paraventricular thalamic nucleus - RE nucl. reuniens - RL nucl. reticularis linearis - SCN suprachiasmatic nucleus - SMl supramammillary region (pars lateralis) - SMm supramammillary region (pars medialis) - SUB subiculum - TS triangular septal nucleus - VTA ventral tegmental area - ac anterior commissure - bc brachium conjunctivum - bp brachium pontis - cc corpus callosum - fr fasciculus retroflexus - fx fornix - ml medial lemniscus - mlf fasciculus longitudinalis medialis - mp mammillary peduncle - mt mammillary tract - oc optic chiasm - on optic nerve - pc posterior commissure - pt pyramidal tract - sm stria medullaris - st stria terminalis - vhc ventral hippocampal commissure Supported by the Deutsche Forschungsgemeinschaft (Nu 36/2-1)     

Demonstration of afferent connections of the forebrain in Emys orbicularis turtles by the peroxidase method

The transport of horseradish peroxidase (HRP) out of the injection site in the dorsal ventricular ridge was studied in turtles Emys orbicularis. Labeled cells in the forebrain were observed in the paleostriatum among fibers of the lateral forebrain bundle. In the thalamus most of cells containing the granular HRP reaction product were located in the n. rotundus, n. reuniens and perirotundal nuclei (n. dorso-medialis anterior, n. magnocellularis thalami, n (centralis) lateralis, n. dorso-medialis). Fewer labeled cells were revealed in the n. anterior and n. ventralis. The density of labeled cells in the majority of all thalamic nuclei increased if the HRP was extended from the dorsal ventricular ridge into the neostriatum and the pallial thickening with adjacent general cortex. HRP positive cells in the pretectal area, nuclei of the posterior commissura and mesencephalic ventro-lateral tegmentum were observed only in cases when the enzyme was diffused from the injection site into the neostriatum, while the HRP retrograde transport to n. geniculatus lateralis, pars dorsalis was revealed only when HRP was extended into the pallial thickening and adjacent general cortex. Ascending connections of the paleostriatum, thalamic nuclei and mesencephalic tegmentum with telencephalic structures, mainly with the dorsal ventricular ridge, were discussed.     

Septal neurons related with hippocampus increase their firing rate after long-term clomipramine.

In the rat, long-term clomipramine increases the firing rate in lateral septal neurons. Although the hippocampus is the main afference for septal nuclei, it is unknown whether clomipramine increases the firing rate in most of hippocampal-septal neurons. Therefore, the present study explored the actions of long-term clomipramine in lateral septal neurons identified by their relation to the hippocampus. In most recordings, hippocampal stimulation produced a brief excitatory short-latency response, followed by a period of inhibition of firing. These neurons increased their firing rate after clomipramine treatment. Other septal neurons not respondent to hippocampal stimulation did not respond to clomipramine treatment, either. We concluded that only hippocampal-septal neurons are clomipramine responders too, and the drug-induced enhancement of firing rate is likely to be mediated by an interneuron-mediated disinhibition process.     

The Lateral Hypothalamus Is Involved in the Pathway Mediating the Hypotensive Response to Cingulate Cortex-Cholinergic Stimulation

1. The injection of acetylcholine (ACh) into the medial prefrontal cortex (MPFC) caused marked hypotensive response in either unanesthetized or anesthetized rats.2. The present experiment was designed to investigate anatomical connections of the ACh injection site in the MPFC with putative autonomic-related brain nuclei, as well as their possible involvement in the mediation of the hypotensive response to ACh.3. For the above purpose, the bidirectional neuronal tracer biotinylated dextran amine (BDA) was injected into Cg1 and Cg3 areas, within the MPFC of male Wistar rats. Five days later the animals were sacrificed and brain slices were processed and analyzed to determine neuronal projections efferent from as well afferent to the MPFC.4. Neuronal staining was more prominent in regions ipsilateral to the BDA injection site. Prominent efferent projections of the MPFC were observed in the contralateral MPFC; ipsi- and contralateral amygdala and hypothalamus; ipsilateral septal area, diagonal band, and zona incerta.5. Similar but not equal patterns of neuronal labeling were observed when BDA injections were performed within the two adjacent MPFC areas. BDA injections centered in the ACh injection site in the Cg3 area caused strong labeling in the septal area and diagonal band as well as an overall hypothalamic labeling. Within the hypothalamus an intense cortical projection was observed in the lateral hypothalamus (LH). BDA injections into the Cg1 area caused a more evident labeling of the amygdaloid complex.6. Neuronal cell bodies were evident throughout the MPFC as well as in the sensory-motor cortex when BDA was injected into the LH, thus indicating a massive ipsilateral cortical projection from the Cg3 to the LH.7. Bilateral NMDA-induced lesions within the LH caused a significant attenuation of the depressor responses to ACh injection in the MPFC, whereas unilateral lesions were marginally effective. These results indicate the involvement of the LH in the mediation of the hypotensive response to ACh injection into the MPFC as well as the bilateral distribution of the hypotensive pathway.     

Fatigue of the dorsal neck muscles initiates c-fos expression in the rat spinal cord and hypothalamus

Fatiguing stimulation of the dorsal neck muscles in rats is shown to induce significant up-regulation of the c-fos expression in the ipsilateral cervical cord, contralateral hypothalamic nuclei, periaqueductal gray, and lateral parabrachial nucleus. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 354–357, July–August, 2006.