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PubMed1995

Developmental transformation of dendritic arbors in mouse whisker thalamus.

Neurons in slices though the somatosensory thalamus of postnatal day 6 and adult mice were injected with Lucifer yellow. Dendritic arbors on postnatal day 6 are confined to single barreloids (single whisker representations); in adults they are seven times longer, extending beyond their barreloid to adjacent barreloids. The postnatal transformation of dendritic arbors by total process growth and extension to adjacent barreloids suggests a developmental change in the role of these cells from instructing whisker pattern formation to integrating sensory information from more than one whisker.

Aging↗
PubMed1996

The role of brain noradrenaline in cortical activation and behavior: a study of lesions of the locus coeruleus, medial thalamus and hippocampus-neocortex and of muscarinic blockade in the rat.

Local injection of 6-hydroxydopamine in the locus coeruleus resulted in a 90% depletion of noradrenaline (NA) in the cerebral cortex as assessed by high-pressure liquid chromatography. This NA depletion had no effect on scopolamine-resistant hippocampal rhythmical slow activity and only an occasional effect on scopolamine-resistant neocortical low voltage fast activity. However, NE depletion resulted in a slight deficit in a behavioral swim-to-platform test and increased the deficit produced on the test by systemic treatment with scopolamine. Large surgical lesions of the medial thalamus or hippocampal formation plus posterior neocortex greatly increased the behavioral deficit produced by scopolamine. It is concluded that ascending noradrenergic projections play only a modest and possibly indirect role in the control of electrocortical activation and that a number of different brain lesions increase the behavioral impairment produced by central muscarinic blockade.

Animals↗
PubMed1990

Visual properties of neurons in the thalamus and striopallidar complex of the human brain.

In parkinsonian patients diagnosed and treated with the aid of long-term intracerebral electrodes, neuronal impulse activity (NIA) was recorded in different nuclei of the thalamus and striopallidar complex during visual testing for orientation sensitivity. Neuronal populations responding only to the presented stimuli with specific angular orientations have been revealed. Orientation-selective neurons have been found with significant responses in NIA observed to the same angular orientations of stimuli during 90 degrees head tilts. It is hypothesized that the visual perception constancy can be maintained with the participation of cerebral nuclei containing such neurons on the basis of convergence of motor, somatosensory and visual information.

Action Potentials↗
PubMed1993

Differential phasic modulation of short and long latency afferent sensory transmission to single neurons in the ventroposterolateral thalamus in behaving rats.

Single neurons were recorded in the forepaw area of the ventroposterolateral (VPL) thalamus of awake rats during rest and running behaviors. Locomotor step cycle dependent changes of the transmission of the short (4.0 +/- 0.1-10.1 +/- 0.3 ms, SEURs) and the long (10.2 +/- 0.2-26.0 +/- 2.1 ms, LEURs) latency somatic sensory responses were tested by generating post-stimulus time histograms of these neurons' responses to stimulation through electrodes chronically implanted under the skin of the forepaw. The magnitudes of firing during these responses were measured and normalized as percent increases over background firing. Times of footfall were determined through frame-by-frame analyses of video recordings and peri-footfall histograms were generated to differentiate a total of 40 VPL thalamic neurons into two types, footfall responsive (n = 21) and unresponsive (n = 19) neurons. Perifootfall gating patterns were determined for both types of cells. The SEURs and the LEURs showed significantly different phasic sensory modulation patterns across the locomotor step cycle. Major difference of the sensory modulations between footfall responsive and footfall unresponsive cells was noted during swing phase of the locomotor step cycle. In footfall responsive cells, the SEURs were suppressed most strongly just after footfall, while the LEURs were tonically suppressed during late stance and swing phases. The SEURs were disinhibited during the swing phase, while the LEURs were disinhibited during the middle stance phase. In footfall unresponsive cells, the LEURs were suppressed more strongly around footfall event than the SEURs were.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

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.

Animals↗
PubMed1981

The projection from the dorsal lateral geniculate nucleus of the thalamus to extrastriate visual association cortex in the macaque monkey.

Both autoradiographic and horseradish peroxidase tracing techniques were used to characterize a projection from the dorsal lateral geniculate (DLG) nucleus of the thalamus to visual association cortex (extrastriate cortex) in the macaque monkey. The results show that medium to large caliber DLG axons end to discontinuous terminal "patches" in layers V and lower IV of extrastriate cortex. There is a topographical organization to these projections which are mainly to area 19 and anterior 18 located on the lateral and medial surfaces of the hemisphere. Apparently there are no DLG projections to any of the cortical subdivision located within the lunate and superior temporal sulci.

Afferent Pathways↗
PubMed1983

The laminar arrangement of limbic thalamocortical neurons in the lateropulvinar nuclei of the cat thalamus.

The topical organization of limbic cortical projections of the lateropulvinar nuclei of the thalamus in the cat was studied with the horseradish peroxidase (HRP) technique. The dorsal margins of the dorsal lateral, medial pulvinar and lateral pulvinar nuclei project to the postsubicular and presubicular areas (presubiculum in a wide sense), the most dorsal parts of these nuclei projecting to the retrosplenial area, and the dorsal parts to the cingular area. These three zones of limbic thalamocortical neurons in the lateropulvinar nuclei are arranged in lamination from the surface inward, and may be called presubicular, retrosplenial and cingular zones.

Animals↗
PubMed1985

Regional differences in mu 1-binding of [3H][D-Ala2,D-Leu5]-enkephalin: comparisons of thalamus and cortex in the rat.

Typically, mu 1-sites represent approximately 25-35% of binding in rat brain homogenates. Competition studies indicated that approximately 60% of [3H][D-Ala2,D-Leu5]-enkephalin ([3H]DADLE) binding in the thalamus was inhibited by low concentrations of morphine (2-5 nM). This high proportion of mu 1-binding was anticipated based upon the low levels of delta-sites and the high levels of mu 1-sites in this region observed in autoradiography studies. In contrast, morphine lowered [3H]DADLE binding by only approximately 5-15% in the cortex, a region known to possess large amounts of delta- and few mu 1-receptors. These results support previous autoradiography studies and illustrate the advantages of using tissue regions in the characterization of opiate receptor subtypes.

Animals↗
PubMed1986

Neural analysis of temporally patterned sounds in the frog's thalamus: processing of pulse duration and pulse repetition rate.

We conducted a single unit study of auditory neurons in the central thalamic nucleus of the northern leopard frog. These cells, unlike those of the posterior thalamic nucleus (J. Comp. Physiol., 150 (1983) 333-344), were broadly tuned and sensitive to one or more temporal features (pulse duration and repetition rate) of complex sound signals. When compared with previous studies, these results suggest that temporal and spectral information may be processed separately by distinct populations of neurons within the frog's thalamus.

Acoustic Stimulation↗
PubMed1986

Single pallidal neurons project both to the striatum and thalamus in the rat.

Collateral projections of single small pallidal neurons to the striatum and paraventricular nucleus of the thalamus were observed in the rat using a fluorescent retrograde double labeling technique. This population of pallidal cells was almost separate from the more predominant pallidal cell group projecting to the subthalamic nucleus. We propose that the globus pallidus proper might have the same two functionally distinct populations (limbic and motor), that have been well documented in the striatum and entopeduncular nucleus.

Animals↗
PubMed1987

The effects of intrathecally applied noradrenaline and 5-hydroxytryptamine on spinal nocifensive reflexes and the rostral transmission of noxious information to the thalamus in the rat.

The effects of intrathecally applied noradrenaline (NA) and 5-hydroxytryptamine (5-HT) on a spinal nocifensive reflex and nociceptive responses recorded from rat ventrobasal thalamus have been compared. A dose of 15 nmol NA increased the tail flick latency (TFL) for approximately 120 min (n = 12) in rats lightly anaesthetised with Saffan. A dose of 260 nmol 5-HT increased the TFL for approximately 21 min (n = 7). In rats anaesthetised with urethane, 15 nmol NA produced a reversible reduction in the response of 15 ventrobasal thalamic units to noxious stimulation lasting approximately 36 min (n = 15). A dose of 260 nmol 5-HT reduced thalamic nociceptive responses for approximately 25 min (n = 12). This suggests that spinal interneurones subserving the tail flick reflex are more sensitive to NA than spinal neurones involved in the transmission of noxious information supraspinally. In contrast, intrathecally applied 5-HT is equipotent in its action on both groups of neurones involved in nociceptive mechanisms.

Action Potentials↗
PubMed1989

Distribution of CCK mRNA in particular regions (hippocampus, periaqueductal grey and thalamus) of the rat by in situ hybridization.

Cholecystokinin (CCK) mRNA was detected by in situ hybridization at high magnification in some rat brain regions where CCK octapeptide (CCK-8) is thought to produce its pharmacological effects. The labeling of the dentate gyrus and the sparse but intensively stained cells found in the CA1 layer, stratum radiatum and hilus could correspond to interneurons involved in hippocampal neural activity, in agreement with excitatory responses induced by local injection of CCK-8. The intense labeling of the Edinger-Westphal nucleus and more generally the presence of CCK mRNA in the periaqueductal gray and thalamus ventrobasal nuclei could account for the various effects of CCK in pain transmission.

Animals↗
PubMed1990

Parietal projection of thalamocortical fibers from the ventroanterior-ventrolateral complex of the cat thalamus.

Anterograde labelling following focal injections of Phaseolus vulgaris leucoagglutinin was used to identify the parietal distribution of thalamocortical (TC) fibers from the ventroanterior-ventrolateral (VA-VL) complex of the cat thalamus. In injections in the ventrolateral or the caudal part of the VA-VL complex, labelled TC fibers were distributed in layers I, III and IV of the parietal areas 5a and/or 5b, whereas in injections located more rostrally or dorsomedially, labelled TC fibers were almost confined to layer I.

Animals↗
PubMed1990

Arborization of corticothalamic axons in the auditory thalamus of the cat: a PHA-L tracing study.

As a result of Phaseolus vulgaris leucoagglutinin (PHA-L) injection in the primary auditory cortex of the cat, portions of corticofugal axons could be traced individually in the reticular complex of the thalamus (RE) and in the medial geniculate body (MGB). On their way to the MGB, axons were seen to give off collaterals which terminated in RE. In the MGB, an individual corticofugal axon was fully reconstructed. It ramified at 3 distinct frontal levels in the rostral half of the pars lateralis (LV). Its terminal branches gave rise to boutons en passant and terminaux in a stripe of LV (parallel to the isofrequency contours), overlapping a cluster of retrogradely labeled neurons, supporting at the microscopic level the principle of the reciprocity of thalamocortical and corticothalamic projections.

Animals↗
PubMed1992

Interconnections between the pretectum and visual thalamus in reptiles, Caiman crocodilus.

Interconnections between the visual thalamus and the pretectum were investigated in one species of reptiles, Caiman crocodilus, by injections of horseradish peroxidase into nucleus rotundus. Nucleus pretectalis was identified as a major target of rotundal efferents as well as a significant input to nucleus rotundus. The presence of a pretectal nucleus with neural connections and topographic location similar to nucleus pretectalis of Caiman has been described in lizards and pigeons. Taken together, these observations suggest that this pretectal nuclear group and its associated fiber path may be a feature common to all non-mammalian amniotes.

Alligators and Crocodiles↗
PubMed1992

Azimuthal processing in the posterior auditory thalamus of cats.

The responses to free-field acoustic stimuli of 157 units in the auditory thalamus of anesthetized cats were studied in relation to the localization of pure tone stimuli in the azimuthal plane. Units were classified as 'directional' if their firing rates at sound levels in excess of 20 dB above threshold varied by more than 50% as a function of azimuth. Sixty-five % of the units in the nucleus of the brachium of the inferior colliculus and 30% in the ventral division of the medial geniculate body were found to be directional, suggesting different processing channels for sound localization between colliculus and cortex.

Acoustic Stimulation↗
PubMed1995

Ultrastructural immunolocalization of muscarinic acetylcholine receptor in the dorsal thalamus of rat.

The ultrastructural distribution of muscarinic acetylcholine receptor (mAChR) in the dorsal thalamus of the adult rat was studied by means of pre-embedding immunocytochemistry using the monoclonal antibody M35. mAChR immunoreactivity (ir) was present with variable intensity in the different thalamic nuclei, but with a similar subcellular localization. Labeling was restricted to neuronal cell bodies and dendrites, where it was both in the cytoplasm and along the cytoplasmic side of the plasma membrane, in areas post-synaptic to small terminals with round clear vesicles but also in non-synaptic areas. Glial cells were unlabeled. By combining the pre-embedding immunostaining for mAChR with post-embedding immunogold labeling for GABA it was shown that GABAergic terminals made synaptic contacts with cholinoceptive structures, but no mAChR ir was present at their post-synaptic sites.

Animals↗
PubMed1988

Depression by morphine and the non-opioid analgesic agents, metamizol (dipyrone), lysine acetylsalicylate, and paracetamol, of activity in rat thalamus neurones evoked by electrical stimulation of nociceptive afferents.

Pyrazolone and salicylic acid derivatives and the aniline derivative, paracetamol, are often classified as peripherally acting analgesic agents, while morphine is a centrally acting analgesic agent. Since indications exist that the non-opioid analgesic agents can also produce central effects, experiments were carried out on rats under urethane anaesthesia in which activity was recorded from single neurones in the dorsomedial part of the ventral nucleus (VDM) of the thalamus that was elicited by supramaximal electrical stimulation of nociceptive afferents in the sural nerve. In addition, activity was recorded in ascending axons of the spinal cord which was evoked by electrical stimulation of nociceptive afferents in the sural nerve. The substances studied were morphine, the pyrazolone derivatives, metamizol (dipyrone) and aminophenazone ('Pyramidon'), lysine acetylsalicylate, and paracetamol. All drugs were found to depress dose-dependently evoked activity in VDM neurones after intravenous (i.v.) injection. The ED50 of morphine in depressing evoked activity in VDM neurones is 0.05 mg/kg. Morphine also dose-dependently reduced activity in ascending axons of the spinal cord, the ED50 being 1.7 mg/kg. The ED50 of metamizol in depressing evoked activity in VDM neurones is 120 mg/kg, and that of aminophenazone is 22.7 mg/kg. The 2 ED50 values differ significantly. It has been found previously that metamizol increased nociceptive activity in some ascending axons and aminophenazone increased this activity in all ascending axons tested. The ED50 of lysine acetylsalicylate in depressing evoked activity in VDM neurones is 74 mg/kg. The drug did not reduce nociceptive activity in ascending axons of the spinal cord. The ED50 of paracetamol in depressing evoked activity in VDM neurones is 19.0 mg/kg. Paracetamol did not depress nociceptive activity in ascending axons of the spinal cord at a dose as high as 150 mg/kg administered by intraperitoneal injection. Naloxone (0.2 mg/kg i.v.) abolished the depressant effects of morphine but failed to reduce those of the non-opioid analgesic agents even at a high dose (1 mg/kg i.v.). Unlike morphine, the non-opioid analgesic agents did not completely block evoked activity in VDM neurones but only partially blocked their activation. The results suggest that the non-opioid analgesic agents tested can produce a central analgesic effect which, however, is weaker than that of morphine.

Acetaminophen↗