Gigantocellular Tegmental Field


A stimulation of the gigantocellular tegmental field (FTG) in the medulla oblongata often increases systemic arterial blood pressure (SAP) and decreases heart rate (HR).  

FLI was also observed in the gigantocellular tegmental field (FTG -- medial nuclei of reticular formation), the spinal trigeminal nucleus, in the medullar raphe nuclei (ncl.  

Intracellular recordings and neurobiotin labeling of medial pontine gigantocellular tegmental field (m-PFTG) neurons in the undrugged, naturally sleeping cat were performed to establish the relationship between soma size and membrane potential (MP) activity before and during the onset of the rapid eye movement (REM) phase of sleep.  

Microinjection of monosodium L-glutamate (Glu) into the locus coeruleus (LC), the gigantocellular tegmental field (FTG), the rostral ventrolateral medulla (RVLM), and the dorsomedial medulla (DM) produced pressor responses, whereas injection into the lateral tegmental field (FTL), the nucleus of tractus solitarii (NTS), and the caudal ventrolateral medulla (CVLM) produced depressor responses.  

Using anesthetized cats, the authors examined the noradrenergic modulation of the glutamate induced pressor and depressor responses in various brainstem areas, including pontine gigantocellular tegmental field (FTG), dorsomedial medulla (DM), rostral ventrolateral medulla (RVLM), and caudal ventrolateral medulla (CVLM).  

Microinjection of Glu (0.1 M, 30 nL) into gigantocellular tegmental field (FTG), dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM) induced increases of the systemic arterial pressure (SAP) and the sympathetic vertebral nerve activities (VNA), while its microinjection into caudal ventrolateral medulla (CVLM) induced decreases of SAP and VNA.  

Cholinergic cell groups were found in an area extending from the central to the gigantocellular tegmental field and the periventricular gray corresponding to the pedunculopontine tegmental nucleus (PPT), the laterodorsal tegmental nucleus (LDT), and the parabrachial nucleus.  

In intact animals, monosodium L-glutamate (Glu, 0.1 mol/L, 50 nL) was microinjected into pressor areas of the locus coeruleus (LC), gigantocellular tegmental field (GTF), rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and the depressor areas of caudal ventrolateral medulla (CVLM).  

In 24 cats under chloralose/urethane anesthesia changes of systemic arterial pressure (SAP) and sympathetic vertebral nerve activities (VNA) were induced by microinjection of glycine (Gly, 1.0 M, 50 nl) into the pressor areas of the rostral pons, i.e., locus coeruleus-parabrachial nucleus (LC-PBN), nucleus of gigantocellular tegmental field-lateral tegmental field (FTG-FTL), and dorsomedial (DM) and ventrolateral (VLM) medulla.  

Pressor sites included gigantocellular tegmental field (FTG) and dorsal medulla (DM) and rostral ventrolateral medulla (VLM).  

LC is different from the gigantocellular tegmental field (FTG) located in the same rostral pons.  

In addition, a few NADPH-diaphorase/glutamate immunoreactive cells were found in the paraolivary area and gigantocellular tegmental field, in the external cuneate and infratrigeminal nuclei.  

Brain sites under exploration included gigantocellular tegmental field and lateral tegmental field (FTG-FTL), the dorsomedial (DM) and ventrolateral (VLM) medulla which produced pressor responses; caudal VLM (CVLM) and paramedian reticular nucleus (PRN) which produced depressor responses.  

Using immunohistochemistry and retrograde transport techniques, this study demonstrates that serotonin (5-HT) cells in the dorsal tegmental gray of the pons at rostrocaudal from P1 to P6 levels are sources of bilateral serotonergic projections to the gigantocellular tegmental field of the medial pontine and medullary reticular formation in the cat.  

The present study examined the hypothesis that cholinoceptive reticular mechanisms in the gigantocellular tegmental field (FTG) of the medial pontine reticular formation cause state-dependent changes in the discharge of parabrachial neurons.  

Stimulation of the dorsal gigantocellular tegmental field-periventricular grey (dFTG-PVG) produced pressor responses.  

Recently, the authors have shown that morphine-mediated REM sleep inhibition is localized to a specific region of the pontine reticular formation: the gigantocellular tegmental field (FTG).  

Areas eliciting a decrease in UB motility listed in decreasing order are gigantocellular tegmental field, parvocellular reticular nucleus, and ambiguus nucleus.  

The pontine inhibitory sites corresponded to the medial area of the central tegmental field (FTC) and the central area of the gigantocellular tegmental field (FTG), bilaterally.  

This study examined the hypothesis that cholinergic receptor mechanisms within the gigantocellular tegmental field (FTG) of the medial pontine reticular formation can cause state-dependent changes in the firing rates of parabrachial nuclear complex (PBNC) neurons.  

In vivo microdialysis of the gigantocellular tegmental field (FTG) was performed in 10 adult male cats while respiration was being measured.  

A moderate density of cell bodies containing the peptide was observed in the ventral nucleus of the lateral lemniscus, accessory dorsal tegmental nucleus, retrofacial nucleus and in the lateral reticular nucleus, whereas a low density of such perikarya was found in the interpeduncular nucleus, nucleus incertus, nucleus sagulum, gigantocellular tegmental field, nucleus of the trapezoid body, nucleus praepositus hypoglosii, lateral and magnocellular tegmental fields, nucleus of the solitary tract, nucleus ambiguous and in the nucleus intercalatus.  

By contrast, the nuclei abducens, the nucleus of the trapezoid body, preolivary, interpeduncularis, infratrigeminal, gigantocellular tegmental field, coeruleus and dorsal motor nucleus of the vagus had the lowest density.  

Similar effects were also obtained following injection of carbachol in the gigantocellular tegmental field (FTG) (0.25 microliter, 0.5-1.0 microgram/microliter).  

We consider mechanisms by which the interaction between gigantocellular tegmental field (FTG) cells and locus coeruleus (LC) activity proposed by the sleep cycle model may differentially modulate the information processing carried out in the hippocampus as described by the attentional model.  

There are three different descending projections from the bulbar gigantocellular tegmental field (BFTG) in the cat, as defined by intracellular recording and intracellular horseradish peroxidase (HRP) techniques. The first pathway arises from neurons which send axons to the contralateral medial longitudinal fasciculus (cMLF neurons); cMLF neurons show excitatory postsynaptic potentials (EPSPs) after stimulation of the ipsilateral pontine gigantocellular tegmental field (PFTG).  

This study demonstrates that the laterodorsal tegmental nucleus (LDT) and pedunculopontine tegmental nucleus (PPT) are sources of cholinergic projections to the cat pontine reticular formation gigantocellular tegmental field (PFTG).  

Two different descending projections from the pontine gigantocellular tegmental field (PFTG) were defined by the use of intracellular recording and intracellular horseradish peroxidase (HRP) techniques in the cat.  

The trajectories and the cells of origin of the pontobulbar gigantocellular tegmental field descending pathways were studied in the cat using anterograde WGA-HRP and retrograde HRP techniques. Four main descending pathways and cells of origin were delineated: (1) Predominantly large neurons in the pontine gigantocellular tegmental field (average soma diameter = 43.4 microns) and rostral bulbar gigantocellular tegmental field (41.3 microns) gave rise to reticulospinal fibers descending in the ipsilateral medial longitudinal fasciculus and ventral funiculus and distributed in laminae V-X with an ipsilateral predominance. (2) Predominantly large neurons (46.9 microns) in the bulbar gigantocellular tegmental field gave rise to reticulospinal fibers descending in the contralateral medial longitudinal fasciculus and ventral funiculus. (3) Neurons of predominantly medium size (29.5 microns) in the pontine gigantocellular tegmental field gave rise to reticuloreticular fibers descending directly to and distributed bilaterally in the bulbar reticular formation. (4) Neurons of predominantly medium size (28.9 microns) in the bulbar gigantocellular tegmental field gave rise to reticulospinal fibers descending in the ipsilateral reticular formation and lateral funiculus.  

Computer analysis and statistical processing of the unit activity showed that the majority of neurons (65.2%) in the gigantocellular tegmental field were discharging with high frequency during active wakefulness and paradoxical sleep as compared to slow-wave sleep in unrestrained rats. Involvement of the gigantocellular tegmental field in the neurophysiological mechanisms of phases and stages of the sleep-wakefulness cycle is discussed..  

Thirteen of 16 RS cells excited by bradykinin were located in the gigantocellular tegmental field (FTG); the other three cells were in the paramedian nucleus (PR).  

SRT cells were antidromically activated from the medial medullary reticular formation near the gigantocellular tegmental field contralateral (35 cells), ipsilateral (15 cells), or both contralateral and ipsilateral (11 cells) to the recording site.  

There was a very high percentage (75-90%) of monosynaptic latency postsynaptic potentials (PSPs) in mPRF neurons in response to microstimulation of 3 BRF areas: the magnocellular tegmental field (FTM), the bulbar gigantocellular tegmental field (BFTG), and bulbar lateral tegmental field (BFTL).  

These results suggest that cells and/or fibers located within the lateral tegmental field rather than those within the medial gigantocellular tegmental field of the pons are most important for the generation of the cluster of events that characterize paradoxical sleep..  

By examining the same neuron before and after chloral hydrate injection, it was found that chloral hydrate anesthesia completely abolished the excitatory responses of DRN serotonergic neurons to auditory and visual stimuli, as well as their excitatory response to electrical stimulation of the gigantocellular tegmental field (FTG) in the pontine reticular formation.  

Intracellular recordings in the medial portion of the pontine reticular formation in the gigantocellular tegmental field and the tegmental reticular nucleus of the naturally sleeping cat have indicated the presence of a class of neurons whose discharges have a long lead time (50-300 ms) prior to, and a high correlation with primary ponto-geniculo-occipital (PGO) waves in the lateral geniculate nucleus (LGN) ipsilateral to the recording site; we term these neurons long lead PGO wave positive neurons.  

Lesions were concentrated in the region of the nucleus locus coeruleus (LC)-an area implicated in the mediation of muscular atonia during PS-but also included other reticular (pontine gigantocellular tegmental field: FTG), and nonreticular (vestibular, cerebellar, central grey, collicular) areas.  

We have compared the effects of electrolytic and kainic acid lesions of the pontine gigantocellular tegmental field (FTG) upon paradoxical sleep (PS).  

Presynaptic boutons of the gigantocellular tegmental field (FTG) of the brain stem reticular formation were analyzed by sterological techniques for changes in numerical and volumetric density during early postnatal development.  

The pontine gigantocellular tegmental field (FTG) does not play any role in paradoxical sleep (PS) since the destruction of the cell bodies of the FTG with ka├»nic acid does not alter PS in the Cat.  

The extracellularly recorded discharge of pontine gigantocellular tegmental field (FTG) neurons was studied in the cat during the transitional phase of sleep (TPS), which signifies in this study the shift from slow wave sleep (S) to paradoxical sleep (PS).  

Bilateral lesions of the pontine gigantocellular tegmental field in the cat resulted in the complete elimination of paradoxical sleep during 3 weeks postoperative recording. These results indicate that neurons whose perikarya and/or processes are located within the pontine gigantocellular tegmental field and which are not part of the noradrenaline locus coeruleus complex, are critical for paradoxical sleep..  

In addition, labeled cells are localized to the contralateral dorsomedial gigantocellular tegmental field as well as the nucleus praepositus hypoglossi of both sides, evidence that these neuronal groups may also be involved in eye movement control..  

Units histologically localized to the gigantocellular tegmental field (FTG) showed the earliest and most prominent discharge rate increases relative to eye movement onset.  

The time course of the rate deceleration shown by these neurons during transition from postural rigidity to muscular atonia represents a mirror image of the rate acceleration which affects most of the pontine reticular neurons located in the gigantocellular tegmental field (FTG) during the induced cataplectic episodes.  

The neurons of the pontine reticular formation had a selectivity which was higher than that of the neurons located in the locus coeruleus-raphe system; moreover the cells of the gigantocellular tegmental field (FTG) had the highest selectivity of all pontine reticular structures studied.  

The positive effects are graded, being maximal in the gigantocellular tegmental field and less marked in adjacent nuclei.  

Neurons localized to the area implicated in control of the desynchronized phase of sleep, the gigantocellular tegmental field (FTG), show the most phasic or clustered discharge pattern, as evinced by initial peaks in the autocorrelations.  

A model for control of the desynchronized phase of the sleep cycle postulates reciprocal interaction between cells in the pontine gigantocellular tegmental field (FTG cells) and cells in the nucleus locus coeruleus and nucleus subcoeruleus (LC cells).  


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