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At least 19 recordsLinked to original sources
PubMed2000

Connections of some auditory-responsive posterior thalamic nuclei putatively involved in activation of the hypothalamo-pituitary-adrenocortical axis in response to audiogenic stress in rats: an anterograde and retrograde tract tracing study combined with Fos expression.

Prior studies in our laboratory demonstrated that part of the thalamus is necessary for activating the hypothalamo-pituitary-adrenocortical (HPA) axis in response to audiogenic stress in rats. The present studies were designed to determine how the auditory-responsive thalamic nuclei might activate the HPA axis. Both retrograde [Fluoro-Gold (FG)] and anterograde [Phasoleus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amines (BDA)] tracers were employed to study the putative connectivity between the thalamus and the medial parvocellular region of the hypothalamic paraventricular nucleus (PAmp). In addition, rats receiving FG in the PAmp were subjected to audiogenic stress, and the distribution of both FG and the protein product of the immediate-early gene c-fos, Fos, were determined by double immunohistochemistry, to help assess putative functional links between the auditory-responsive thalamic nuclei and PAmp. The results of PAmp FG placement indicated retrogradely labeled cells in several areas, including the bed nucleus of the stria terminalis, hypothalamic regions, the supramammillary nucleus, some thalamic regions, and importantly, a few multisensory nuclei of the thalamus, including the parvicellular division of the subparafascicular and posterior intralaminar nuclei. Injections of the tracers PHA-L or BDA into these auditory-responsive posterior thalamic nuclei provided further evidence of projections to the PAmp. In addition, several forebrain areas were observed to receive moderate to heavy innervation. These areas included most of the regions described above, which, in turn, project to the PAmp. Because cells in the multisensory thalamic nuclei, hypothalamic, and forebrain areas were double labeled with FG and Fos, the results suggest that either direct projections from the thalamus to PAmp neurons, or indirect projections from the thalamus to stress-responsive forebrain areas projecting to the PAmp, might mediate activation of the HPA axis by audiogenic stress.

Acoustic Stimulation↗
PubMed1983

Neocortical projections of the suprageniculate and posterior thalamic nuclei in the marsupial brush-tailed possum, Trichosurus vulpecula (Phalangeridae), with a comparative commentary on the organization of the posterior thalamus in marsupial and placental mammals.

Axonal transport methods were used to determine the extent and organisation of neocortical projections from the suprageniculate (SG) and posterior (PO) thalamic nuclei in the brush-tailed possum. Our findings show that SG projects extensively to the auditory cortex, overlapping the cortical projection field of the medial geniculate nucleus, and to the immediately neighbouring association cortex. Though the input relationships of SG appear similar to those reported for other mammals, placental and marsupial, a strong SG projection to auditory cortex has not been reported previously. Neocortical relationships of PO are characterised by an orderly point-to-point projection to all but the most rostral parts of the motor-somaesthetic cortex. There is also a substantial projection to the entire posterior parietal association cortex. The PO-neocortex projection is reciprocally organised. The PO-neocortical projection in the possum is similar to that reported in the Virginia opossum, rat, and several other mammals. There is a major difference in organisation in comparison with certain monkeys where the PO projection is much more restricted and does not involve the motor and somaesthetic cortex. We conclude that PO is similarly organised in many, though not all, mammals, including the marsupials, rodents, insectivores, and prosimian primates. The possum SG, on the other hand, is clearly distinct from other mammals in its extensive projection to auditory cortex, though we cannot say at present whether this a general property of marsupial mammals or a peculiarity restricted to this species and possibly its close relatives.

Animals↗
PubMed1996

Organization of the visual reticular thalamic nucleus of the rat.

The visual sector of the reticular thalamic nucleus has come under some intense scrutiny over recent years, principally because of the key role that the nucleus plays in the processing of visual information. Despite this scrutiny, we know very little of how the connections between the reticular nucleus and the different areas of visual cortex and the different visual dorsal thalamic nuclei are organized. This study examines the patterns of reticular connections with the visual cortex and the dorsal thalamus in the rat, a species where the visual pathways have been well documented. Biotinylated dextran, an anterograde and retrograde tracer, was injected into different visual cortical areas [17; rostral 18a: presumed area AL: (anterolateral); caudal 18a: presumed area LM (lateromedial); rostral 18b: presumed area AM (anteromedial); caudal 18b: presumed area PM (posteromedial)] and into different visual dorsal thalamic nuclei (posterior thalamic, lateral geniculate nuclei), and the patterns of anterograde and retrograde labelling in the reticular nucleus were examined. From the cortical injections, we find that the visual sector of the reticular nucleus is divided into subsectors that each receive an input from a distinct visual cortical area, with little or no overlap. Further, the resulting pattern of cortical terminations in the reticular nucleus reflects largely the patterns of termination in the dorsal thalamus. That is, each cortical area projects to a largely distinct subsector of the reticular nucleus, as it does to a largely distinct dorsal thalamic nucleus. As with each of the visual cortical areas, each of the visual dorsal thalamic (lateral geniculate, lateral posterior, posterior thalamic) nuclei relate to a separate territory of the reticular nucleus, with little or no overlap. Each of these dorsal thalamic territories within the reticular nucleus receives inputs from one or more of the visual cortical areas. For instance, the region to the reticular nucleus that is labelled after an injection into the lateral geniculate nucleus encompasses the reticular regions which receive afferents from cortical areas 17, rostral 18b and caudal 18b. These results suggest that individual cortical areas may influence the activity of different dorsal thalamic nuclei through their reticular connections.

Animals↗
PubMed1977

Single units activities in ventral posterior and posterior group thalamic nuclei during nociceptive and non nociceptive stimulations in the cat.

The purpose of this study was to define, in hyperventilated and unanesthetized cats, the role of the posterior thalamic nuclei in pain mechanisms. Unit activities of these structures were compared to those of the ventro-posterior nucleus during non-noxious (touch, brushing) and noxious stimulations (pinches and intra-arterial injections of bradykinin into the limbs). 135 cells with somatic inputs and clear peripheral excitatory receptive field were studied. The cells driven by noxious stimulations were located in the posterior group nuclei as anatomically defined by Rinvik. These units, preferentially excited from contralateral receptive fields, were localized in POm, POl, suprageniculate nuclei, the magnocellular division of the medial geniculate body (Mgmc) and the ventral part of the lateral posterior nucleus. At this level two groups of units were found: those driven only by noxious stimulations and those driven by both noxious and non-noxious stimulations. On contrast, cells recorded at the levels of the VPm and VPl were not activated by noxious stimuli. These results emphasize the role of the posterior thalamic nuclei in pain processing.

Animals↗
PubMed1984

[Neuronal populations in the posterior group of thalamic nuclei projecting into the amygdaloid complex and auditory cortex in the cat].

Location of neurons in posterior thalamic nuclei and neighbouring structures of the midbrain regions projecting to the amygdaloid complex and auditory cortex of cat was studied by the method of horseradish peroxidase. The main sources of these brain region projections to amygdaloid complex are peripeduncular , subparafascicular and suprageniculate nuclei and caudal division of the medial geniculate body. The cells of origin of projections to the auditory cortex are located in all medial geniculate nuclei and wide regions of the posterior thalamic group. Neuron pools projecting to the auditory cortex and amygdala exist in medial parts of the posterior thalamic nuclei. The role of posterior thalamic nuclei in transmission of auditory signals to amygdala is discussed.

Amygdala↗
PubMed1998

Some forebrain connections of the gustatory system in the goldfish Carassius auratus visualized by separate DiI application to the hypothalamic inferior lobe and the torus lateralis.

The neuroanatomical connections of the diencephalic torus lateralis and inferior lobe of the goldfish (Carassius auratus) were studied by retrograde and anterograde labeling with the carbocyanine dye DiI. Both structures have afferents originating in the central zone of the dorsal telencephalic area as well as in the supracommissural nucleus of the ventral telencephalic area, and in the secondary gustatory, tertiary gustatory, and posterior thalamic nuclei. Both structures investigated have efferents to the tertiary gustatory and posterior thalamic nuclei, as well as to the dorsal hypothalamus (dorsal hypothalamic neuropil) and superior reticular formation. The torus lateralis receives additional afferents from the secondary general visceral nucleus and, sparsely, from the dorsal tegmental nucleus. The inferior lobe receives additional afferents from the medial zone of the dorsal telencephalic area, as well as from the suprachiasmatic, posterior pretectal, central posterior thalamic, caudal preglomerular, two tegmental nuclei (T1 and T2), corpus mamillare, and, sparsely, from the cerebellar valvula. The inferior lobe has additional efferents to the dorsal and ventral thalamus and subglomerular nucleus. The lateral torus and inferior lobe are also mutually interconnected. The lateral torus and inferior lobe map topographically onto the vagal-related (intraoral) or onto the facial-related (extraoral) portions, respectively, of both the secondary and tertiary gustatory nuclei. Because the posterior thalamic nucleus is reciprocally connected with the lateral torus and inferior lobe and is further known to project in turn to the area doralis telencephali, it likely represents a quaternary gustatory projection nucleus to the telencephalon in cyprinids. Whereas the lateral torus seems to be exclusively involved with gustatory and general visceral systems, the inferior lobe has inputs from additional sensory (e.g., octavolateralis, visual) systems, and, thus, likely represents a multisensory integration center.

Animals↗
PubMed1996

A single-cell study of the axonal projections arising from the posterior intralaminar thalamic nuclei in the rat.

Thalamostriatal projections arising from the posterior intralaminar nuclei (P1; the parafascicular nucleus and the adjacent caudalmost part of the posterior thalamic group) were studied in rats by tracing the axons of small pools of neurons labelled anterogradely with biocytin. Thirteen P1 cells were also stained by juxta cellular application of the tracer. Relay cells of P1 nuclei have a morphology that differs radically from the classical descriptions of the bushy cells which represent the main neuronal type of the sensory thalamic relay nuclei. P1 cells have ovoid or polygonal somata of approximately 20-25 microm, from which emerge four or five thick, long and poorly branched dendrites bearing spines and filamentous appendages; their dendritic domains extend for up to 1.5 mm. Before leaving the nucleus 20% of axons give off collaterals that ramify locally. All axons course through the thalamic reticular nucleus, where they also distribute collaterals, and arborize massively in the striatum and sparsely in the cerebral cortex. At the striatal level four or five collaterals leave the main axon and terminate in patches scattered dorsoventrally within a rostrocaudally oriented slab. As revealed by calbindin D-28k immunohistochemistry, only the matrix compartment receives terminations from P1 axons. The cortical branch form small terminal puffs centred upon layer VI of the motor cortex. Before entering the striatum some axons of the parafascicular nucleus give rise to descending collaterals that arborize in the entopeduncular nucleus, in the subthalamic nucleus and in the vicinity of the red nucleus. Other axons arising from the caudal part of the posterior group send descending branches only to the entopeduncular nucleus. These findings show that P1 cells belong to a distinct category of thalamic relay neurons which, beside their massive projection to the striatum, also distribute collaterals to other components of the basal ganglia. Moreover, these results provide the first direct evidence that virtually all P1 cells project to both striatum and cerebral cortex. Finally, it is proposed on the basis of morphological, histochemical and hodological criteria that the caudal part of the posterior thalamic group in the rat is homologous to the suprageniculate-limitans nuclei of cats and primates.

Afferent Pathways↗
PubMed2003

Electrical properties affecting discharge of units of the mid and posterolateral thalamus of conscious cats.

Discharge properties in response to intracellularly applied, rectangular currents were measured in units of the mid (lateralis dorsalis and centrolateral nuclei) and posterolateral (lateralis posterior and pulvinar nuclei) thalamus of conscious cats. A separate aim was to determine if neuronal excitability changed in association with changes in stimulus-evoked activity after the animals were trained to discriminate between two acoustic stimuli when performing a conditioned motor response. Low threshold spike (l.t.s.) discharges were observed in three of 272 cells given 1 nA intracellular, hyperpolarizing current pulses of 40 ms duration. This finding supports the view that thalamic neurons of conscious animals operate mainly in the relay as opposed to the oscillatory mode. Application of larger and longer hyperpolarizing currents in the cells produced rebound l.t.s. discharges, supporting the expectation that most thalamic neurons are capable of producing this type of discharge. Decrements of spike afterhyperpolarizations (AHP) and broadening of spike bases upon repeated discharge also were observed in each area of the thalamus studied. After conditioning, changes were found in the posterolateral thalamus (but not in the mid-thalamus) in the proportions of cells with spontaneous, rapid (>/=50 Hz), repetitive, discharges (RRD) and rapid, sustained discharges at rates >/=100 Hz during application of depolarizing current (RSD). In the posterolateral thalamus the percentage of units responding to 1 nA depolarization with RSD fell from 71% before conditioning to 45% after conditioning. The percentage of cells with RRD decreased from 69% to 46%. The changes were accompanied by a 3 mV hyperpolarization of the membrane potentials of the cells and a decrease in baseline activity. After conditioning, increases in excitability were found in cells of the mid thalamus that responded selectively to the click conditioned stimulus (CS) that elicited the conditioned response, and decreases in excitability were found in cells of the posterolateral thalamus that responded to the discriminative acoustic stimulus (DS) to which the animals were trained not to respond. An earlier study showed a potentiation of discharge in response to the CS in units of the midthalamus after similar conditioning and a reduction of the proportion of DS responsive units and peak discharge to the DS in units of the posterolateral thalamus. We conclude that the discharge properties of units of the mid and posterolateral thalamus can change to support discrimination between acoustic stimuli of different functional significance after conditioning.

Acoustic Stimulation↗
PubMed1991

Neuroanatomical localization of kappa 1 and kappa 2 opioid receptors in rat and guinea pig brain.

The neuroanatomical localization of kappa opioid receptors in rat and guinea pig brain was determined by quantitative in vitro receptor autoradiography. Our study shows striking differences in kappa 1 and kappa 2 receptor distributions both between species and within each species. In the rat brain, kappa 1 sites (labeled by [3H]U-69,593) are of low density and confined to a small number of structures. These include the claustrum, endopiriform nucleus, caudate putamen, nucleus accumbens, midline nuclear group of the thalamus, superficial grey layer of the superior colliculus, and central grey. kappa 2 sites (labeled by [3H]ethylketocyclazocine or [3H]bremazocine under conditions in which mu, delta, and kappa 1 binding was suppressed) are more widely distributed throughout all levels of rat brain. kappa 2 sites occur at high density in the caudate putamen, nucleus accumbens, amygdala, thalamus, and interpeduncular nuclei. In guinea pig brain, kappa 1 sites predominate and are of high density in layers I and VI of the neocortex, claustrum, endopiriform nucleus, caudate putamen, nucleus accumbens, and molecular layer of the cerebellum. As in rat brain, kappa 2 sites in guinea pig are more uniformly and widely distributed throughout the brain than are kappa 1 sites. The highest density of kappa 2 sites is in the dorsal parabrachial nucleus, interpeduncular nuclei, mammillary nuclei, and posterior thalamic nuclei. Results from this study demonstrate important interspecies differences in the distribution of kappa 1 and kappa 2 opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesics↗
PubMedDate not supplied

[Role of several subcortical nuclei in the conduction of visual afferentation during early ontogeny].

Characteristics of EPs in different areas of the visual cortex elicited by stimulation of subcortical nuclei (LGB, posterior thalamic nuclei and superior colliculi) were studied in cat's fetuses during the last 10 days of their antenatal development. It was shown that both in the striate and in accessory visual areas the EPs are negative oscillations with a small initial positivity. Latencies of the EPs to stimulation of the thalamic nuclei make from 18 to 25 msec in different cortical areas and those to the stimulation of the superior colliculi--from 40 to 45 msec. Laminar analysis of EPs elicited in the occipital cortical area by the stimulation of LGB revealed two foci of depolarization; the one with shorter EP latency is localized in the depth of the cortex. The role of the extrageniculate ascending system and of different groups of fibers of the geniculocortical system in the formation of the main EP components in the visual cortex in early ontogenesis is discussed.

Animals↗
PubMed2000

Differential projection of the posterior paralaminar thalamic nuclei to the amygdaloid complex in the rat.

The thalamic paralaminar nuclei that border the medial and ventral edges of the medial geniculate body, viz. the suprageniculate nucleus (SG), the posterior intralaminar nucleus (PIN), the medial division of the medial geniculate nucleus (MGm), and the peripeduncular nucleus (PP), are regarded as important extralemniscal relay nuclei for sensory stimuli and as an important link for the direct transmission of sensory stimuli to the amygdala. Each of these thalamic nuclei receives a unique pattern of afferent input but an unresolved question is, how each of these thalamic nuclei project to the amygdala and whether there are zones of convergence and/or non-overlapping regions within amygdaloid target nuclei. Small injections of PHA-L or Miniruby, which were made into single thalamic nuclei at different rostrocaudal levels, revealed a non-uniform distribution of anterogradely labeled axons within the amygdaloid complex. Injections into the SG, MGm, and rostral PIN predominantly labeled axons in the laterodorsal and lateroventral portions of the lateral nucleus of the amygdala (LA). Axons from the MGm were located rather in the dorsal part of the LA, whereas SG-derived axons were concentrated in the ventrolateral part of the LA. Injections into the PP labeled axons predominantly in the medial part of the LA, whereas after injections into the caudal PIN axons were seen in the entire LA. In addition, the PIN projects heavily to the anterior basomedial nucleus and medial division of the central nucleus, whereas this projection is virtually absent from the other thalamic nuclei. The lateral part of the central nucleus and the basal nucleus of the amygdala are spared by axons from the thalamic paralaminar nuclei. The present results suggest that, despite a considerable degree of convergence of the thalamoamygdaloid projection in the lateral nucleus, each thalamic nucleus plays a unique role in the transmission of sensory stimuli to the amygdala and in the modulation of intraamygdaloid circuits.

Amygdala↗
PubMed1996

Efferent connections of the caudal part of the globus pallidus in the rat.

The efferent connections of the caudal pole of the globus pallidus (GP) were examined in the rat by employing the anterograde axonal transport of Phaseolus vulgaris leucoagglutinin (PHA-L), and the retrograde transport of fluorescent tracers combined with choline acetyltransferase (ChAT) or parvalbumin (PV) immunofluorescence histochemistry. Labeled fibers from the caudal GP distribute to the caudate-putamen, nucleus of the ansa lenticularis, reuniens, reticular thalamic nucleus (mainly its posterior extent), and along a thin strip of the zona incerta adjacent to the cerebral peduncle. The entopeduncular and subthalamic nuclei do not appear to receive input from the caudal GP. Descending fibers from the caudal GP course in the cerebral peduncle and project to posterior thalamic nuclei (the subparafascicular and suprageniculate nuclei, medial division of the medial geniculate nucleus, and posterior intralaminar nucleus/peripeduncular area) and to extensive brainstem territories, including the pars lateralis of the substantia nigra, lateral terminal nucleus of the accessory optic system, nucleus of the brachium of the inferior colliculus, nucleus sagulum, external cortical nucleus of the inferior colliculus, cuneiform nucleus, and periaqueductal gray. In cases with deposits of PHA-L in the ventral part of the caudal GP, labeled fibers in addition distribute to the lateral amygdaloid nucleus, amygdalostriatal transition area, cerebral cortex (mainly perirhinal, temporal, and somatosensory areas) and rostroventral part of the lateral hypothalamus. Following injections of fluorescent tracer centered in the lateral hypothalamus, posterior intralaminar nucleus, substantia nigra, pars lateralis, or lateral terminal nucleus, a substantial number of retrogradely labeled cells is observed in the caudal GP. None of these cells express ChAT immunoreactivity, but, except for the ones projecting to the lateral hypothalamus, a significant proportion is immunoreactive to PV. Our results indicate that caudal GP efferents differ from those of the rostral GP in that they project to extensive brainstem territories and appear to be less intimately related to intrinsic basal ganglia circuits. Moreover, our data suggest a possible participation of the caudal GP in feedback loops involving posterior cortical areas, posterior striatopallidal districts, and posterior thalamic nuclei. Taken as a whole, the projections of the caudal GP suggest a potential role of this pallidal district in visuomotor and auditory processes.

Amidines↗