The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform

Yasuyuki Yamashita - One of the best experts on this subject based on the ideXlab platform.

  • Signal intensity of the normal Pontine Tegmentum on T2-weighted MR imaging
    Neuroradiology, 2006
    Co-Authors: Chiaki Asao, Toshinori Hirai, Masanori Imuta, T Okuda, Yoshitaka Goto, Masamichi Hamaguchi, Katsuro Sagara, Yukunori Korogi, Yasuyuki Yamashita
    Abstract:

    On T2-weighted MR images, the Pontine Tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the Pontine Tegmentum normally differs from that of the Pontine base. We evaluated the signal intensity of the Pontine Tegmentum and Pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the Tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the Tegmentum to the base. The CNR was significantly higher for the Tegmentum than the base at each level of the pons ( P

  • signal intensity of the normal Pontine Tegmentum on t2 weighted mr imaging
    Neuroradiology, 2006
    Co-Authors: Chiaki Asao, Toshinori Hirai, Masanori Imuta, T Okuda, Yoshitaka Goto, Masamichi Hamaguchi, Katsuro Sagara, Yukunori Korogi, Yasuyuki Yamashita
    Abstract:

    On T2-weighted MR images, the Pontine Tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the Pontine Tegmentum normally differs from that of the Pontine base. We evaluated the signal intensity of the Pontine Tegmentum and Pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the Tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the Tegmentum to the base. The CNR was significantly higher for the Tegmentum than the base at each level of the pons (P<0.0001), and the signal intensity ratio of the Tegmentum to the base in the upper pons was significantly higher in children than in adults (P<0.005). On T2-weighted images, a high signal intensity of the Pontine Tegmentum is frequently seen in neurologically healthy subjects. This finding should not be considered abnormal, particularly in children.

Isabel De Andrés - One of the best experts on this subject based on the ideXlab platform.

  • The Transition Between Slow-Wave Sleep and REM Sleep Constitutes an Independent Sleep Stage Organized by Cholinergic Mechanisms in the Rostrodorsal Pontine Tegmentum
    Frontiers in Neuroscience, 2019
    Co-Authors: Carlos Carrera-cañas, Miguel Garzón, Isabel De Andrés
    Abstract:

    There is little information on either the transition state occurring between slow-wave sleep and REM sleep, as well as about its neurobiological bases. This transition state, which is known as the intermediate state (IS), is well defined in rats but poorly characterized in cats. Previous studies in our laboratory demonstrated that cholinergic stimulation of the perilocus coeruleus α nucleus (PLCα) in the Pontine Tegmentum of cats induced two states: wakefulness with muscle atonia and a state of dissociated sleep we have called the SPGO state. The SPGO state has characteristics in common with the IS, such including the presence of ponto-geniculo-occipital waves (PGO) and EEG synchronization with δ wave reduction. Therefore, the aims of the present study were (1) to characterize the IS in the cat and, (2), to study the analogy between the SPGO and the different sleep stages showing PGO activity, including the IS. Polygraphic recordings of ten cats were used. In seven cats carbachol microinjections (20-30nL, 0.01-0.1M) were delivered in the PLCα. In the different states, PGO waves were analyzed and power spectra obtained for the δ, θ, α and β bands of the EEG from the frontal and occipital cortices, and for the θ hippocampal band. Statistical comparisons were made between the values obtained from the different states. The results indicate that the IS constitutes a state with characteristics that are distinct from both the preceding slow-wave sleep and the following REM sleep, and that SPGO presents a high analogy with the IS. Therefore, the SPGO state induced by administering carbachol in the PLCα nucleus seems to be an expression of the physiological IS of the cat. Consequently, we propose that the PLCα region, besides being involved in the mechanisms of muscle atonia, may also be responsible for organizing the transition from slow-wave sleep to REM sleep.

  • sleep wakefulness effects after microinjections of hypocretin 1 orexin a in cholinoceptive areas of the cat oral Pontine Tegmentum
    European Journal of Neuroscience, 2008
    Co-Authors: Elena Morenobalandran, Fernando Reinososuarez, Miguel Garzón, Cristina Bodalo, Isabel De Andrés
    Abstract:

    : Hypocretinergic/orexinergic neurons, which are known to be implicated in narcolepsy, project to the Pontine Tegmentum areas involved in the control of rapid eye movement (REM) sleep. Here, we report the effects on sleep-wakefulness produced by low-volume microinjections of hypocretin (Hcrt)1 (20-30 nL, 100, 500 and 1000 microm) and carbachol (20-30 nL, 0.1 m) delivered in two areas of the oral Pontine Tegmentum of free-moving cats with electrodes for chronic sleep recordings: in the dorsal oral Pontine Tegmentum (DOPT) and in the ventral part of the oral Pontine reticular nucleus (vRPO). Carbachol in the DOPT produced dissociate polygraphic states, with some but not all REM sleep signs. In contrast, carbachol in the vRPO produced a shift with short latency from wakefulness (W) to REM sleep with all of its polygraphic and behavioral signs. Hcrt-1 in the DOPT increased W and decreased both slow-wave sleep (SWS) and REM sleep during the first 3 h post-drug. The same doses of Hcr-1 in the vRPO produced a significant suppression of REM sleep without a definitive trend for changes in the other states. Both groups showed significant decreases in the number of transitions from SWS to REM sleep. Thus, Hcrt-1 produced distinct effects in cholinoceptive areas of the oral Pontine Tegmentum; in the DOPT it promoted W, suppressed SWS and probably defacilitated REM sleep, and in the vRPO it directly inhibited REM sleep. Hypocretinergic/orexinergic signaling is lost in narcoleptics and this absence would mean that Pontine defacilitation/inhibition of REM sleep would also be absent, explaining why these patients can fall directly into REM sleep from W.

  • Brain structures and mechanisms involved in the generation of REM sleep.
    Sleep Medicine Reviews, 2001
    Co-Authors: Fernando Reinoso-suárez, Isabel De Andrés, Margarita L Rodrigo-angulo, Miguel Garzón
    Abstract:

    Abstract This article reviews the central nervous mechanisms involved in the broad network that generates and maintains REM sleep. Experimental investigations have identified the Pontine Tegmentum as the critical substrate for REM sleep mechanisms. Several Pontine structures are involved in the generation of each particular polygraphic event that characterizes REM sleep: desynchronization in the electroencephalogram, theta rhythm in the hippocampus, muscle atonia, pontogeniculooccipital waves and rapid eye movements. The Pontine Tegmentum also holds the region where cholinergic stimulation can trigger all the behavioural and bioelectric signs of REM sleep. The exact location has been investigated and amply discussed over the last few years. Studies in the authors» laboratory, mapping the Pontine Tegmentum with small volume carbachol (a cholinergic agonist) microinjections, have demonstrated that the executive neurons for REM sleep generation are neither located in the dorsal part of the Pontine Tegmentum, nor diffusely spread through the medial Pontine reticular formation: they are concentrated in a discrete area in the ventral part of the oral Pontine reticular nucleus (vRPO). In turn, the vRPO has connections with structures involved in the generation of the other states of the sleep–wake cycle as well as with structures responsible for the generation of each of the different events characterizing REM sleep. This allows us to propose the vRPO as the crucial region for REM sleep generation. Related research, with invivo and invitro experiments, into the actions of different neurotransmitters on vRPO neurones indicates that not only acetylcholine but other neurotransmitters have an active key role in vRPO REM sleep generation mechanisms.

  • location and anatomical connections of a paradoxical sleep induction site in the cat ventral Pontine Tegmentum
    European Journal of Neuroscience, 1994
    Co-Authors: Fernando Reinososuarez, Isabel De Andrés, Margarita L Rodrigoangulo, Elisia Rodriguezveiga
    Abstract:

    : The brainstem mechanisms for the generation of paradoxical sleep are under considerable debate. Previous experiments in cats have demonstrated that injections of the cholinergic agonist carbachol into the oral Pontine Tegmentum elicit paradoxical sleep behaviour and its polygraphic correlates. The different results on the Pontine structures that mediate this effect do not agree. We report here that limited microinjections of a carbachol solution into the ventral part of the oral Pontine reticular nucleus in the cat induce, with a short latency, a dramatic, long-lasting increase in paradoxical sleep. Moreover, neuronal tracing experiments show that this Pontine site is connected with brain structures responsible for the different bioelectric events of paradoxical sleep. These two facts suggest that the ventral part of the oral Pontine reticular nucleus is a nodal link in the neuronal network underlying paradoxical sleep mechanisms.

Miguel Garzón - One of the best experts on this subject based on the ideXlab platform.

  • The Transition Between Slow-Wave Sleep and REM Sleep Constitutes an Independent Sleep Stage Organized by Cholinergic Mechanisms in the Rostrodorsal Pontine Tegmentum
    Frontiers in Neuroscience, 2019
    Co-Authors: Carlos Carrera-cañas, Miguel Garzón, Isabel De Andrés
    Abstract:

    There is little information on either the transition state occurring between slow-wave sleep and REM sleep, as well as about its neurobiological bases. This transition state, which is known as the intermediate state (IS), is well defined in rats but poorly characterized in cats. Previous studies in our laboratory demonstrated that cholinergic stimulation of the perilocus coeruleus α nucleus (PLCα) in the Pontine Tegmentum of cats induced two states: wakefulness with muscle atonia and a state of dissociated sleep we have called the SPGO state. The SPGO state has characteristics in common with the IS, such including the presence of ponto-geniculo-occipital waves (PGO) and EEG synchronization with δ wave reduction. Therefore, the aims of the present study were (1) to characterize the IS in the cat and, (2), to study the analogy between the SPGO and the different sleep stages showing PGO activity, including the IS. Polygraphic recordings of ten cats were used. In seven cats carbachol microinjections (20-30nL, 0.01-0.1M) were delivered in the PLCα. In the different states, PGO waves were analyzed and power spectra obtained for the δ, θ, α and β bands of the EEG from the frontal and occipital cortices, and for the θ hippocampal band. Statistical comparisons were made between the values obtained from the different states. The results indicate that the IS constitutes a state with characteristics that are distinct from both the preceding slow-wave sleep and the following REM sleep, and that SPGO presents a high analogy with the IS. Therefore, the SPGO state induced by administering carbachol in the PLCα nucleus seems to be an expression of the physiological IS of the cat. Consequently, we propose that the PLCα region, besides being involved in the mechanisms of muscle atonia, may also be responsible for organizing the transition from slow-wave sleep to REM sleep.

  • sleep wakefulness effects after microinjections of hypocretin 1 orexin a in cholinoceptive areas of the cat oral Pontine Tegmentum
    European Journal of Neuroscience, 2008
    Co-Authors: Elena Morenobalandran, Fernando Reinososuarez, Miguel Garzón, Cristina Bodalo, Isabel De Andrés
    Abstract:

    : Hypocretinergic/orexinergic neurons, which are known to be implicated in narcolepsy, project to the Pontine Tegmentum areas involved in the control of rapid eye movement (REM) sleep. Here, we report the effects on sleep-wakefulness produced by low-volume microinjections of hypocretin (Hcrt)1 (20-30 nL, 100, 500 and 1000 microm) and carbachol (20-30 nL, 0.1 m) delivered in two areas of the oral Pontine Tegmentum of free-moving cats with electrodes for chronic sleep recordings: in the dorsal oral Pontine Tegmentum (DOPT) and in the ventral part of the oral Pontine reticular nucleus (vRPO). Carbachol in the DOPT produced dissociate polygraphic states, with some but not all REM sleep signs. In contrast, carbachol in the vRPO produced a shift with short latency from wakefulness (W) to REM sleep with all of its polygraphic and behavioral signs. Hcrt-1 in the DOPT increased W and decreased both slow-wave sleep (SWS) and REM sleep during the first 3 h post-drug. The same doses of Hcr-1 in the vRPO produced a significant suppression of REM sleep without a definitive trend for changes in the other states. Both groups showed significant decreases in the number of transitions from SWS to REM sleep. Thus, Hcrt-1 produced distinct effects in cholinoceptive areas of the oral Pontine Tegmentum; in the DOPT it promoted W, suppressed SWS and probably defacilitated REM sleep, and in the vRPO it directly inhibited REM sleep. Hypocretinergic/orexinergic signaling is lost in narcoleptics and this absence would mean that Pontine defacilitation/inhibition of REM sleep would also be absent, explaining why these patients can fall directly into REM sleep from W.

  • cellular and subcellular distributions of delta opioid receptor activation sites in the ventral oral Pontine Tegmentum of the cat
    Brain Research, 2006
    Co-Authors: Maria Ximena Alvirabotero, Miguel Garzón
    Abstract:

    Abstract The ventral division of the reticular oral Pontine nucleus (vRPO) is a Pontine Tegmentum region critically involved in REM sleep generation. Previous reports of morphine microinjections in the cat Pontine Tegmentum have shown that opioid receptor activation in this region modulates REM sleep. Even though opiate administration has marked effects on sleep–wake cycle architecture, the distribution of opioid receptors in vRPO has only been partially described. Using an antiserum directed against delta opioid receptor (DOR), to which morphine binds, in the present study, we use (1) light microscopy to determine DOR cellular distribution in the rostral Pontine Tegmentum and (2) electron microscopy to determine DOR subcellular distribution in the cat vRPO. In the dorsal pons, DOR immunoreactivity was evenly distributed throughout the neuropil of the reticular formation and was particularly intense in the parabrachial nuclei and locus coeruleus; the ventral and central areas of the RPO and locus coeruleus complex were especially rich in DOR-labeled somata. Within the vRPO, DOR was localized mainly in the cytoplasm and on plasma membranes of medium to large dendrites (47.8% of DOR-labeled profiles), which received both symmetric and asymmetric synaptic contacts mainly from non-labeled (82% of total inputs) axon terminals. Less frequently, DOR was distributed presynaptically in axon terminals (19% of DOR-labeled profiles). Our results suggest that DOR activation in vRPO regulates REM sleep occurrence by modulating postsynaptic responses to both excitatory and inhibitory afferents. DOR activation in vRPO could have, however, an additional role in direct modulation of neurotransmitter release from axon terminals.

  • Brain structures and mechanisms involved in the generation of REM sleep.
    Sleep Medicine Reviews, 2001
    Co-Authors: Fernando Reinoso-suárez, Isabel De Andrés, Margarita L Rodrigo-angulo, Miguel Garzón
    Abstract:

    Abstract This article reviews the central nervous mechanisms involved in the broad network that generates and maintains REM sleep. Experimental investigations have identified the Pontine Tegmentum as the critical substrate for REM sleep mechanisms. Several Pontine structures are involved in the generation of each particular polygraphic event that characterizes REM sleep: desynchronization in the electroencephalogram, theta rhythm in the hippocampus, muscle atonia, pontogeniculooccipital waves and rapid eye movements. The Pontine Tegmentum also holds the region where cholinergic stimulation can trigger all the behavioural and bioelectric signs of REM sleep. The exact location has been investigated and amply discussed over the last few years. Studies in the authors» laboratory, mapping the Pontine Tegmentum with small volume carbachol (a cholinergic agonist) microinjections, have demonstrated that the executive neurons for REM sleep generation are neither located in the dorsal part of the Pontine Tegmentum, nor diffusely spread through the medial Pontine reticular formation: they are concentrated in a discrete area in the ventral part of the oral Pontine reticular nucleus (vRPO). In turn, the vRPO has connections with structures involved in the generation of the other states of the sleep–wake cycle as well as with structures responsible for the generation of each of the different events characterizing REM sleep. This allows us to propose the vRPO as the crucial region for REM sleep generation. Related research, with invivo and invitro experiments, into the actions of different neurotransmitters on vRPO neurones indicates that not only acetylcholine but other neurotransmitters have an active key role in vRPO REM sleep generation mechanisms.

  • sleep patterns after carbachol delivery in the ventral oral Pontine Tegmentum of the cat
    Neuroscience, 1998
    Co-Authors: Miguel Garzón, I De Andres, Fernando Reinososuarez
    Abstract:

    Abstract This study examines dose-related effects on sleep produced by low-volume and low-dose carbachol microinjections in the ventral part of the cat nucleus reticularis pontis oralis. Carbachol microinjections (0.04, 0.08, 0.8 or 4  μ g; volume 20 nl) in this location triggered paradoxical sleep with a very short dose-unrelated latency. The four carbachol doses effectively generated all the polygraphic and behavioral signs of paradoxical sleep when microinjected at any level within the ventral part of the nucleus reticularis pontis oralis (AP 0.5 to −3.5, L 0.5–3.5, V 3.5–5.0, on the Reinoso-Suarez atlas [ Topographischer Hirnatlas der Katze (1961); Merck, Darmstadt]). The dose-related increase of total paradoxical sleep time was due to the increase in both the duration and number of paradoxical sleep episodes. This paradoxical sleep increase was associated with a dose-related decrease in the amount of time spent in both slow wave sleep and drowsiness, but not with any decrease in total wakefulness. The lengthening of the latency to slow wave sleep onset was dose related. These results show that the ventral oral Pontine Tegmentum is a very sensitive site for the induction and maintenance of paradoxical sleep.

Chiaki Asao - One of the best experts on this subject based on the ideXlab platform.

  • Signal intensity of the normal Pontine Tegmentum on T2-weighted MR imaging
    Neuroradiology, 2006
    Co-Authors: Chiaki Asao, Toshinori Hirai, Masanori Imuta, T Okuda, Yoshitaka Goto, Masamichi Hamaguchi, Katsuro Sagara, Yukunori Korogi, Yasuyuki Yamashita
    Abstract:

    On T2-weighted MR images, the Pontine Tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the Pontine Tegmentum normally differs from that of the Pontine base. We evaluated the signal intensity of the Pontine Tegmentum and Pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the Tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the Tegmentum to the base. The CNR was significantly higher for the Tegmentum than the base at each level of the pons ( P

  • signal intensity of the normal Pontine Tegmentum on t2 weighted mr imaging
    Neuroradiology, 2006
    Co-Authors: Chiaki Asao, Toshinori Hirai, Masanori Imuta, T Okuda, Yoshitaka Goto, Masamichi Hamaguchi, Katsuro Sagara, Yukunori Korogi, Yasuyuki Yamashita
    Abstract:

    On T2-weighted MR images, the Pontine Tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the Pontine Tegmentum normally differs from that of the Pontine base. We evaluated the signal intensity of the Pontine Tegmentum and Pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the Tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the Tegmentum to the base. The CNR was significantly higher for the Tegmentum than the base at each level of the pons (P<0.0001), and the signal intensity ratio of the Tegmentum to the base in the upper pons was significantly higher in children than in adults (P<0.005). On T2-weighted images, a high signal intensity of the Pontine Tegmentum is frequently seen in neurologically healthy subjects. This finding should not be considered abnormal, particularly in children.

Fernando Reinososuarez - One of the best experts on this subject based on the ideXlab platform.

  • sleep wakefulness effects after microinjections of hypocretin 1 orexin a in cholinoceptive areas of the cat oral Pontine Tegmentum
    European Journal of Neuroscience, 2008
    Co-Authors: Elena Morenobalandran, Fernando Reinososuarez, Miguel Garzón, Cristina Bodalo, Isabel De Andrés
    Abstract:

    : Hypocretinergic/orexinergic neurons, which are known to be implicated in narcolepsy, project to the Pontine Tegmentum areas involved in the control of rapid eye movement (REM) sleep. Here, we report the effects on sleep-wakefulness produced by low-volume microinjections of hypocretin (Hcrt)1 (20-30 nL, 100, 500 and 1000 microm) and carbachol (20-30 nL, 0.1 m) delivered in two areas of the oral Pontine Tegmentum of free-moving cats with electrodes for chronic sleep recordings: in the dorsal oral Pontine Tegmentum (DOPT) and in the ventral part of the oral Pontine reticular nucleus (vRPO). Carbachol in the DOPT produced dissociate polygraphic states, with some but not all REM sleep signs. In contrast, carbachol in the vRPO produced a shift with short latency from wakefulness (W) to REM sleep with all of its polygraphic and behavioral signs. Hcrt-1 in the DOPT increased W and decreased both slow-wave sleep (SWS) and REM sleep during the first 3 h post-drug. The same doses of Hcr-1 in the vRPO produced a significant suppression of REM sleep without a definitive trend for changes in the other states. Both groups showed significant decreases in the number of transitions from SWS to REM sleep. Thus, Hcrt-1 produced distinct effects in cholinoceptive areas of the oral Pontine Tegmentum; in the DOPT it promoted W, suppressed SWS and probably defacilitated REM sleep, and in the vRPO it directly inhibited REM sleep. Hypocretinergic/orexinergic signaling is lost in narcoleptics and this absence would mean that Pontine defacilitation/inhibition of REM sleep would also be absent, explaining why these patients can fall directly into REM sleep from W.

  • sleep patterns after carbachol delivery in the ventral oral Pontine Tegmentum of the cat
    Neuroscience, 1998
    Co-Authors: Miguel Garzón, I De Andres, Fernando Reinososuarez
    Abstract:

    Abstract This study examines dose-related effects on sleep produced by low-volume and low-dose carbachol microinjections in the ventral part of the cat nucleus reticularis pontis oralis. Carbachol microinjections (0.04, 0.08, 0.8 or 4  μ g; volume 20 nl) in this location triggered paradoxical sleep with a very short dose-unrelated latency. The four carbachol doses effectively generated all the polygraphic and behavioral signs of paradoxical sleep when microinjected at any level within the ventral part of the nucleus reticularis pontis oralis (AP 0.5 to −3.5, L 0.5–3.5, V 3.5–5.0, on the Reinoso-Suarez atlas [ Topographischer Hirnatlas der Katze (1961); Merck, Darmstadt]). The dose-related increase of total paradoxical sleep time was due to the increase in both the duration and number of paradoxical sleep episodes. This paradoxical sleep increase was associated with a dose-related decrease in the amount of time spent in both slow wave sleep and drowsiness, but not with any decrease in total wakefulness. The lengthening of the latency to slow wave sleep onset was dose related. These results show that the ventral oral Pontine Tegmentum is a very sensitive site for the induction and maintenance of paradoxical sleep.

  • location and anatomical connections of a paradoxical sleep induction site in the cat ventral Pontine Tegmentum
    European Journal of Neuroscience, 1994
    Co-Authors: Fernando Reinososuarez, Isabel De Andrés, Margarita L Rodrigoangulo, Elisia Rodriguezveiga
    Abstract:

    : The brainstem mechanisms for the generation of paradoxical sleep are under considerable debate. Previous experiments in cats have demonstrated that injections of the cholinergic agonist carbachol into the oral Pontine Tegmentum elicit paradoxical sleep behaviour and its polygraphic correlates. The different results on the Pontine structures that mediate this effect do not agree. We report here that limited microinjections of a carbachol solution into the ventral part of the oral Pontine reticular nucleus in the cat induce, with a short latency, a dramatic, long-lasting increase in paradoxical sleep. Moreover, neuronal tracing experiments show that this Pontine site is connected with brain structures responsible for the different bioelectric events of paradoxical sleep. These two facts suggest that the ventral part of the oral Pontine reticular nucleus is a nodal link in the neuronal network underlying paradoxical sleep mechanisms.