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Philip Winn - One of the best experts on this subject based on the ideXlab platform.

  • the Pedunculopontine Tegmental Nucleus a functional hypothesis from the comparative literature
    Movement Disorders, 2016
    Co-Authors: Philip Winn
    Abstract:

    We present data from animal studies showing that the Pedunculopontine Tegmental Nucleus-conserved through evolution, compartmentalized, and with a complex pattern of inputs and outputs-has functions that involve formation and updates of action-outcome associations, attention, and rapid decision making. This is in contrast to previous hypotheses about Pedunculopontine function, which has served as a basis for clinical interest in the Pedunculopontine in movement disorders. Current animal literature points to it being neither a specifically motor structure nor a master switch for sleep regulation. The Pedunculopontine is connected to basal ganglia circuitry but also has primary sensory input across modalities and descending connections to pontomedullary, cerebellar, and spinal motor and autonomic control systems. Functional and anatomical studies in animals suggest strongly that, in addition to the Pedunculopontine being an input and output station for the basal ganglia and key regulator of thalamic (and consequently cortical) activity, an additional major function is participation in the generation of actions on the basis of a first-pass analysis of incoming sensory data. Such a function-rapid decision making-has very high adaptive value for any vertebrate. We argue that in developing clinical strategies for treating basal ganglia disorders, it is necessary to take an account of the normal functions of the Pedunculopontine. We believe that it is possible to use our hypothesis to explain why Pedunculopontine deep brain stimulation used clinically has had variable outcomes in the treatment of parkinsonism motor symptoms and effects on cognitive processing. © 2016 International Parkinson and Movement Disorder Society.

  • updating of action outcome associations is prevented by inactivation of the posterior Pedunculopontine Tegmental Nucleus
    Neurobiology of Learning and Memory, 2013
    Co-Authors: Duncan A A Maclaren, David I G Wilson, Philip Winn
    Abstract:

    The Pedunculopontine Tegmental Nucleus (PPTg) is in a pivotal position between the basal ganglia and brainstem: it is able to influence and regulate all levels of basal ganglia and corticostriatal activity as well as being a key component of brainstem reticular and motor control circuitry. Consistent with its anatomical position, the PPTg has previously been shown to process rapid, salient sensory input, is a target for Parkinson’s disease treatments and has been implicated in associative learning. We explicitly investigated the role of the posterior pPPTg (pPPTg) in action–outcome processes, where actions are performed with the goal-directed aim of obtaining an anticipated outcome. We assessed rats’ sensitivity to degradation of the contingency between actions (lever pressing) and outcomes (food reward) during either inactivation of pPPTg by microinjection of the GABA agonist muscimol or control infusions of saline. In response to the degradation of contingency between lever press and food reward, saline treated rats rapidly reduced rates of lever pressing whereas muscimol treated rats (pPPTg inactivation) maintained previous lever pressing rates. In contrast, when the contingency between lever press and food reward was unchanged saline and muscimol treated rats maintained their previous rates of lever pressing. This shows that the pPPTg is critically required for updating associations between actions and outcomes, but not in the continued performance of previously learned associations. These results are consistent with a role for the PPTg in ‘higher-order’ associative learning and are the first to demonstrate a brainstem role in action–outcome learning.

  • The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?-5
    2011
    Co-Authors: Claire L Rostron, Morag J Farquhar, Mary P Latimer, Philip Winn
    Abstract:

    Copyright information:Taken from "The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?"http://www.biomedcentral.com/1471-2202/9/16BMC Neuroscience 2008;9():16-16.Published online 30 Jan 2008PMCID:PMC2257968.

  • The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?-3
    2011
    Co-Authors: Claire L Rostron, Morag J Farquhar, Mary P Latimer, Philip Winn
    Abstract:

    Copyright information:Taken from "The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?"http://www.biomedcentral.com/1471-2202/9/16BMC Neuroscience 2008;9():16-16.Published online 30 Jan 2008PMCID:PMC2257968.ne on the right of the diagrammatic sections. Distance is given from the interaural line in mm

  • The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?-6
    2011
    Co-Authors: Claire L Rostron, Morag J Farquhar, Mary P Latimer, Philip Winn
    Abstract:

    Copyright information:Taken from "The Pedunculopontine Tegmental Nucleus and the Nucleus basalis magnocellularis: Do both have a role in sustained attention?"http://www.biomedcentral.com/1471-2202/9/16BMC Neuroscience 2008;9():16-16.Published online 30 Jan 2008PMCID:PMC2257968. ChAT positive neurons in the same location in an animal who received bilateral infusions of 192 IgG Saporin. Abbreviations: HDB = Horizontal diagonal band of Broca, MCPo = Magnocellular preoptic Nucleus, SIB = Substantia innominata basal part

Eugenio Scarnati - One of the best experts on this subject based on the ideXlab platform.

  • Pedunculopontine Tegmental Nucleus evoked prepulse inhibition of the blink reflex in parkinson s disease
    Clinical Neurophysiology, 2021
    Co-Authors: A Insola, Annamaria Capozzo, Flora Vitale, P Mazzone, Giacomo Della Marca, Eugenio Scarnati
    Abstract:

    Abstract Objective To investigate the effects on the blink reflex (BR) of single stimuli applied to the Pedunculopontine Tegmental Nucleus (PPTg). Methods The BR was evoked by stimulating the supraorbital nerve (SON) in fifteen patients suffering from idiopathic Parkinson’s disease (PD) who had electrodes monolaterally or bilaterally implanted in the PPTg for deep brain stimulation (DBS). Single stimuli were delivered to the PPTg through externalized electrode connection wires 3-4 days following PPTg implantation. Results PPTg stimuli increased the latency and reduced duration, amplitude and area of the R2 component of the BR in comparison to the response recorded in the absence of PPTg stimulation. These effects were independent of the side of SON stimulation and were stable for interstimulus interval (ISI) between PPTg prepulse and SON stimulus from 0 to 110 ms. The PPTg-induced prepulse inhibition of the BR was bilaterally present in the brainstem. The R1 component was unaffected. Conclusions The prepulse inhibition of the R2 component may be modulated by the PPTg. Significance These findings suggest that abnormalities of BR occurring in PD may be ascribed to a reduction of basal ganglia-mediated inhibition of brainstem excitability.

  • neurophysiology of the Pedunculopontine Tegmental Nucleus
    Neurobiology of Disease, 2019
    Co-Authors: Flora Vitale, Annamaria Capozzo, P Mazzone, Eugenio Scarnati
    Abstract:

    The interest in the Pedunculopontine Tegmental Nucleus (PPTg), a structure located in the brainstem at the level of the pontomesencephalic junction, has greatly increased in recent years because it is involved in the regulation of physiological functions that fail in Parkinson's disease and because it is a promising target for deep brain stimulation in movement disorders. The PPTg is highly interconnected with the main basal ganglia nuclei and relays basal ganglia activity to thalamic and brainstem nuclei and to spinal effectors. In this review, we address the functional role of the main PPTg outputs directed to the basal ganglia, thalamus, cerebellum and spinal cord. Together, the data that we discuss show that the PPTg may influence thalamocortical activity and spinal motoneuron excitability through its ascending and descending output fibers, respectively. Cerebellar nuclei may also relay signals from the PPTg to thalamic and brainstem nuclei. In addition to participating in motor functions, the PPTg participates in arousal, attention, action selection and reward mechanisms. Finally, we discuss the possibility that the PPTg may be involved in excitotoxic degeneration of the dopaminergic neurons of the substantia nigra through the glutamatergic monosynaptic input that it provides to these neurons.

  • deep brain stimulation of the Pedunculopontine Tegmental Nucleus improves static balance in parkinson s disease
    2018
    Co-Authors: P Mazzone, Annamaria Capozzo, Flora Vitale, Fabio Viselli, Eugenio Scarnati
    Abstract:

    Abstract Postural instability is a major problem in Parkinson's disease (PD), being poorly responsive to l -dopa treatment. There is now hope that deep brain stimulation (DBS) of the Pedunculopontine Tegmental Nucleus (PPTg) may ameliorate posture problems, likely acting on nondopaminergic pathways. To explore this possibility we investigated PPTg DBS on fluctuations in the center of pressure (CoP) during upright stance. Total length of oscillations (TL) increased in patients under different drug/DBS and eye-state combinations when compared with controls. CoP displacement velocity was higher in off-drug/off-DBS when compared with controls, but was lower when comparing off-drug/on-DBS versus off-drug/off-DBS. The Romberg's index (RI) referring to sway ellipse (SE) did not change when comparing controls versus the four studied treatments. In contrast, significant increases occurred in the RI for TL when comparing controls versus each treatment. TL and SE were higher when l -dopa-treated patients kept their eyes closed, but decreased irrespective of eye state when DBS was applied. We conclude that PPTg DBS may improve l -dopa-resistant axial and postural abnormalities in PD.

  • cholinergic excitation from the Pedunculopontine Tegmental Nucleus to the dentate Nucleus in the rat
    Neuroscience, 2016
    Co-Authors: Flora Vitale, Claudia Mattei, Annamaria Capozzo, Ilaria Pietrantoni, Paolo Mazzone, Eugenio Scarnati
    Abstract:

    Abstract In spite of the existence of Pedunculopontine Tegmental Nucleus (PPTg) projections to cerebellar nuclei, their nature and functional role is unknown. These fibers may play a crucial role in postural control and may be involved in the beneficial effects induced by deep-brain stimulation (DBS) of brainstem structures in motor disorders. We investigated the effects of PPTg microstimulation on single-unit activity of dentate, fastigial and interpositus nuclei. The effects of PPTg stimulation were also studied in rats whose PPTg neurons were destroyed by ibotenic acid and subsequently subjected to iontophoretically applied cholinergic antagonists. The main response recorded in cerebellar nuclei was a short-latency (1.5–2 ms) and brief (13–15 ms) orthodromic activation. The dentate Nucleus was the most responsive to PPTg stimulation. The destruction of PPTg cells reduced the occurrence of PPTg-evoked activation of dentate neurons, suggesting that the effect was due to stimulation of cell bodies and not due to fibers passing through or close to the PPTg. Application of cholinergic antagonists reduced or eliminated the PPTg-evoked response recorded in the dentate Nucleus. The results show that excitation is exerted by the PPTg on the cerebellar nuclei, in particular on the dentate Nucleus. Taken together with the reduction of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in lesioned animals, the iontophoretic experiments suggest that the activation of dentate neurons is due to cholinergic fibers. These data help to explain the effects of DBS of the PPTg on axial motor disabilities in neurodegenerative disorders.

  • unilateral deep brain stimulation of the Pedunculopontine Tegmental Nucleus in idiopathic parkinson s disease effects on gait initiation and performance
    Gait & Posture, 2014
    Co-Authors: Paolo Mazzone, A Insola, Marco Paoloni, Massimiliano Mangone, Valter Santilli, M Fini, Eugenio Scarnati
    Abstract:

    The Pedunculopontine Tegmental Nucleus (PPTg) is a component of the locomotor mesencephalic area. In recent years it has been considered a new surgical site for deep brain stimulation (DBS) in movement disorders. Here, using objective kinematic and spatio-temporal gait analysis, we report the impact of low frequency (40 Hz) unilateral PPTg DBS in ten patients suffering from idiopathic Parkinson's disease with drug-resistant gait and axial disabilities. Patients were studied for gait initiation (GI) and steady-state level walking (LW) under residual drug therapy. In the LW study, a straight walking task was employed. Patients were compared with healthy age-matched controls. The analysis revealed that GI, cadence, stride length and left pelvic tilt range of motion (ROM) improved under stimulation. The duration of the S1 and S2 sub-phases of the anticipatory postural adjustment phase of GI was not affected by stimulation, however a significant improvement was observed in the S1 sub-phase in both the backward shift of centre of pressure and peak velocity. Speed during the swing phase, step width, stance duration, right pelvic tilt ROM phase, right and left hip flexion-extension ROM, and right and left knee ROM were not modified. Overall, the results show that unilateral PPTg DBS may affect GI and specific spatio-temporal and kinematic parameters during unconstrained walking on a straight trajectory, thus providing further support to the importance of the PPTg in the modulation of gait in neurodegenerative disorders.

Mary P Latimer - One of the best experts on this subject based on the ideXlab platform.

Paolo Mazzone - One of the best experts on this subject based on the ideXlab platform.

  • cholinergic excitation from the Pedunculopontine Tegmental Nucleus to the dentate Nucleus in the rat
    Neuroscience, 2016
    Co-Authors: Flora Vitale, Claudia Mattei, Annamaria Capozzo, Ilaria Pietrantoni, Paolo Mazzone, Eugenio Scarnati
    Abstract:

    Abstract In spite of the existence of Pedunculopontine Tegmental Nucleus (PPTg) projections to cerebellar nuclei, their nature and functional role is unknown. These fibers may play a crucial role in postural control and may be involved in the beneficial effects induced by deep-brain stimulation (DBS) of brainstem structures in motor disorders. We investigated the effects of PPTg microstimulation on single-unit activity of dentate, fastigial and interpositus nuclei. The effects of PPTg stimulation were also studied in rats whose PPTg neurons were destroyed by ibotenic acid and subsequently subjected to iontophoretically applied cholinergic antagonists. The main response recorded in cerebellar nuclei was a short-latency (1.5–2 ms) and brief (13–15 ms) orthodromic activation. The dentate Nucleus was the most responsive to PPTg stimulation. The destruction of PPTg cells reduced the occurrence of PPTg-evoked activation of dentate neurons, suggesting that the effect was due to stimulation of cell bodies and not due to fibers passing through or close to the PPTg. Application of cholinergic antagonists reduced or eliminated the PPTg-evoked response recorded in the dentate Nucleus. The results show that excitation is exerted by the PPTg on the cerebellar nuclei, in particular on the dentate Nucleus. Taken together with the reduction of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in lesioned animals, the iontophoretic experiments suggest that the activation of dentate neurons is due to cholinergic fibers. These data help to explain the effects of DBS of the PPTg on axial motor disabilities in neurodegenerative disorders.

  • unilateral deep brain stimulation of the Pedunculopontine Tegmental Nucleus in idiopathic parkinson s disease effects on gait initiation and performance
    Gait & Posture, 2014
    Co-Authors: Paolo Mazzone, A Insola, Marco Paoloni, Massimiliano Mangone, Valter Santilli, M Fini, Eugenio Scarnati
    Abstract:

    The Pedunculopontine Tegmental Nucleus (PPTg) is a component of the locomotor mesencephalic area. In recent years it has been considered a new surgical site for deep brain stimulation (DBS) in movement disorders. Here, using objective kinematic and spatio-temporal gait analysis, we report the impact of low frequency (40 Hz) unilateral PPTg DBS in ten patients suffering from idiopathic Parkinson's disease with drug-resistant gait and axial disabilities. Patients were studied for gait initiation (GI) and steady-state level walking (LW) under residual drug therapy. In the LW study, a straight walking task was employed. Patients were compared with healthy age-matched controls. The analysis revealed that GI, cadence, stride length and left pelvic tilt range of motion (ROM) improved under stimulation. The duration of the S1 and S2 sub-phases of the anticipatory postural adjustment phase of GI was not affected by stimulation, however a significant improvement was observed in the S1 sub-phase in both the backward shift of centre of pressure and peak velocity. Speed during the swing phase, step width, stance duration, right pelvic tilt ROM phase, right and left hip flexion-extension ROM, and right and left knee ROM were not modified. Overall, the results show that unilateral PPTg DBS may affect GI and specific spatio-temporal and kinematic parameters during unconstrained walking on a straight trajectory, thus providing further support to the importance of the PPTg in the modulation of gait in neurodegenerative disorders.

  • unilateral deep brain stimulation of the Pedunculopontine Tegmental Nucleus improves oromotor movements in parkinson s disease
    Brain Stimulation, 2012
    Co-Authors: Paolo Mazzone, A Insola, Luca Padua, Gianni Falisi, T Florio, Eugenio Scarnati
    Abstract:

    Abstract Background Jaw movements are severely affected in Parkinson’s disease. Deep brain stimulation (DBS) of basal ganglia targets is known to ameliorate oromotor control. In this study, we examined the effects of DBS of the Pedunculopontine Tegmental Nucleus (PPTg) on jaw movements in selected parkinsonian patients. Methods The effects of low-frequency (25 Hz) stimulation of the PPTg on jaw movements were investigated through electrognathographic analysis in parkinsonian patients who were selected for PPTg stimulation. Changes in jaw velocity and amplitude during voluntary opening and closing movements of the mouth, as well as the maximum frequency of self-paced sequences of opening and closing cycles, were analyzed. Results Low-frequency stimulation of the PPTg in the OFF-drugs condition significantly improved the opening and closing velocities, vertical amplitude and rhythm of voluntary movements. In some instances, movement parameters during stimulation were within the range of those recorded in healthy controls. Discussion This is the first study investigating the impact of PPTg DBS on oromotor control in parkinsonian patients. The results show that jaw movements may be restored under stimulation and suggest that the Pedunculopontine Nucleus may play a key role in controlling oromotor activity.

  • The Pedunculopontine Tegmental Nucleus: implications for a role in modulating spinal cord motoneuron excitability
    Journal of Neural Transmission, 2011
    Co-Authors: Eugenio Scarnati, Annamaria Capozzo, Tiziana Florio, Giuseppina Confalone, Paolo Mazzone
    Abstract:

    There is evidence that deep brain stimulation (DBS) of the Pedunculopontine Tegmental Nucleus (PPTg) improves parkinsonian motor signs. The mechanisms that mediate these effects and the modifications that occur in the PPTg in Parkinson’s disease (PD) are not fully known and are the object of current debate. The aim of this paper was to critically review available data with respect to (1) the presence of PPTg neurons linked to reticulospinal projections, (2) the involvement of these neurons in modulating spinal reflexes, and (3) the participation of fibers close to or within the PPTg region in such modulation. The PPTg neurons are distributed in a large pontoTegmental region, stimulation of which can evoke activity in hindlimb, shoulder and neck muscles, and potentiate motor responses evoked by stimulation of dorsal roots. This influence seems to be carried out by fast-conducting descending fibers, which likely run in the medial reticulospinal pathway. It is yet unclear which neurotransmitters are involved and on which elements of the gray matter of the spinal cord PPTg fibers synapse. The modulation of spinal cord activity which can be achieved by stimulating the PPTg region seems to be mediated not only by PPTg neurons, but also by tecto-reticular fibers which run in the pontoTegmental area, and which likely are activated during PPTg-DBS. The importance of these fibers is discussed taking into account the degeneration of PPTg neurons in PD and the benefits in gait and postural control that PPTg-DBS exerts in PD. The potential usefulness of PPTg-DBS in other neurodegenerative disorders characterized by neuronal loss in the brainstem is also considered.

  • The deep brain stimulation of the Pedunculopontine Tegmental Nucleus: towards a new stereotactic neurosurgery
    Journal of Neural Transmission, 2011
    Co-Authors: Paolo Mazzone, A Insola, Stefano Sposato, Eugenio Scarnati
    Abstract:

    The application of deep brain stimulation (DBS) to the Pedunculopontine Tegmental Nucleus (PPTg) has required profound modifications of classic neurosurgical techniques and of the criteria for evaluation of clinical results. This review analyzes a novel method of targeting the PPTg, based on angio-computerized tomography (angio-CT) scans and the tridimensional reconstruction of nuclei and cerebral vessels, and considers the advantages of applying these methods in comparison to the more traditional approach based on reference points obtained through the evaluation of the bicommessural line. Validation of the results obtained following unilateral PPTg DBS through neurophysiological recordings and objective measurements of functional parameters suggests that the PPTg may be considered as an initial target for the treatment of motor symptoms in selected patients affected by idiopathic Parkinson’s disease (PD), which, if required, could be followed by DBS of other target areas. Moreover, on the basis of the observations derived from stimulating the PPTg, the potential utility attributed up to date to intraoperative neurophysiological recordings for identifying neurosurgical targets should be revisited, and the need for changes in the intraoperative management of patients has arisen from the body of evidence accumulated over recent years. The results obtained by different groups following PPTg DBS in parkinsonian patients are not uniform, most likely due to a cautious acceptance of this methodology, the experience progressively acquired, the criteria for patient selection and to subtle differences in target location. Although the role of PPTg in PD and/or in other pathologies remains to be clarified, pursuing the traditional approach on classical basal ganglia targets may limit the perspective of DBS based on multiple implantations.

Wendy L Inglis - One of the best experts on this subject based on the ideXlab platform.

  • selective deficits in attentional performance on the 5 choice serial reaction time task following Pedunculopontine Tegmental Nucleus lesions
    Behavioural Brain Research, 2001
    Co-Authors: Wendy L Inglis, Mary C Olmstead, Trevor W Robbins
    Abstract:

    Sustained attention requires the integrity of basal forebrain cholinergic systems. The Pedunculopontine Tegmental Nucleus (PPTg) has direct and indirect connections (via the thalamus) with the basal forebrain, suggesting that the PPTg may also play an important role in attentional processes. We examined this hypothesis by testing the effects of PPTg lesions in rats on performance in the 5-choice serial reaction time test. Bilateral lesions reduced accuracy, increased errors of omission, and increased the latency to correct responses. The deficits were more severe when neuronal damage was bilateral and concentrated in the posterior PPTg. Attentional demands of the task were increased by decreasing the stimulus duration, the stimulus brightness, or the inter-trial interval, and by introducing random bursts of white noise. These challenges impaired performance of all animals, but the magnitude of deficit was increased in the lesioned group. Conversely, lesion-induced deficits were partially alleviated when the attentional demands of the task were reduced. This pattern of results suggests that PPTg lesions produce a global deficit in attention, rather than a specific impairment in one process. The PPTg may control attentional processes through its direct projections to the forebrain cholinergic system or, indirectly, through activation of thalamocortical projections.

  • Pedunculopontine Tegmental Nucleus lesions impair stimulus reward learning in autoshaping and conditioned reinforcement paradigms
    Behavioral Neuroscience, 2000
    Co-Authors: Wendy L Inglis, Mary C Olmstead, Trevor W Robbins
    Abstract:

    The role of the Pedunculopontine Tegmental Nucleus (PPTg) in stimulus-reward learning was assessed by testing the effects of PPTg lesions on performance in visual autoshaping and conditioned reinforcement (CRf) paradigms. Rats with PPTg lesions were unable to learn an association between a conditioned stimulus (CS) and a primary reward in either paradignl. In the autoshaping experiment, PPTg-lesioned rats approached the CS+ and CS- with equal frequency, and the latencies to respond to the two stimuli did not differ. PPTg lesions also disrupted discriminated approaches to an appetitive CS in the CRf paradigm and completely abolished the acquisition of responding with CRf. These data are discussed in the context of a possible cognitive function of the PPTg, particularly in terms of lesion-induced disruptions of attentional processes that are mediated by the thalamus.

  • lesions of the Pedunculopontine Tegmental Nucleus increase sucrose consumption but do not affect discrimination or contrast effects
    Behavioral Neuroscience, 1999
    Co-Authors: Mary C Olmstead, Wendy L Inglis, Chris P Bordeaux, Emily J Clarke, Nick P Wallum, Barry J Everitt, Trevor W Robbins
    Abstract:

    Pedunculopontine Tegmental Nucleus (PPTg) lesions block place preferences to drugs or food only when animals are nondeprived. PPTg lesions also disrupt operant responding, but lesioned rats cannot discriminate active from inactive levers. It is not clear, therefore, whether PPTg lesions block reward or disrupt the ability to differentiate changes in reward magnitude. These hypotheses were tested by measuring sucrose consumption, choice, and contrast effects after PPTg lesions. Both sham and lesioned rats consumed greater amounts of a sucrose solution as the concentration and level of deprivation were increased. Given a choice between 2 solutions, all rats consumed more of the higher concentration. Both groups exhibited contrast effects when the concentration was shifted from 32% to 4% within a session. Somewhat surprisingly, lesions increased sucrose intake when rats were food-restricted. These results suggest that PPTg lesions do not disrupt primary motivation or the ability to evaluate and respond to changes in reward strength.

  • on the relationships between the striatum and the Pedunculopontine Tegmental Nucleus
    Critical Reviews in Neurobiology, 1997
    Co-Authors: Philip Winn, Verity J Brown, Wendy L Inglis
    Abstract:

    In this essay we consider the role of the Pedunculopontine Tegmental Nucleus as a striatal output station. We review the relevant anatomical, electrophysiological, behavioral, and pathological studies and conclude that the Pedunculopontine Tegmental Nucleus occupies an important position in striatal outflow, receiving motor output from the dorsal striatum and information from the ventral striatum relating to limbic processes of motivation and reinforcement. The hypothesis we present is that the Pedunculopontine Tegmental Nucleus is at the very least an integral component of the limbic-motor interface, although in discussing this concept we also assess the likelihood that the limbic-motor interface is in fact a distributed system-that is, that limbic-motor interfacing is not all done by a single structure in the central nervous system but that different aspects of it are served by different systems. We present the hypothesis that the Pedunculopontine Tegmental Nucleus is one critical site through which limbic information concerned with motivation, reinforcement, and the construction of novel associations can gain access to a stream of motor outflow coming from the caudate-putamen and directed toward pontomedullary systems without reference back to the cerebral cortex. This hypothesis is important because it highlights striatal outflow, which is not processed through the cortical re-entry systems, and also emphasizes the importance of pontine systems in cognitive processing.

  • the Pedunculopontine Tegmental Nucleus where the striatum meets the reticular formation
    Progress in Neurobiology, 1995
    Co-Authors: Wendy L Inglis, Philip Winn
    Abstract:

    The Pedunculopontine Tegmental Nucleus (PPTg) contains a population of cholinergic neurons (the Ch5 group) and non-cholinergic neurons. There appears to be functional interdigitation between these two groups, which both have extensive projections. The principal ascending connections are with thalamic nuclei and structures associated with the striatum, including the substantial nigra pars compacta. The descending connections are with a variety of nuclei in the pons, medulla and spinal cord, concerned with autonomic and motor functions. In the past, emphasis has been laid on the role of the PPTg in locomotion and behavioural state control. In this review, we emphasise the role of the PPTg in processing outputs from the striatum. The non-cholinergic neurons receive outflow from both dorsal and vental striatum, and lesions of the PPTg disrupt behaviour associated with each of these. Our review indicates that the PPTg is less concerned with the induction of locomotion and more concerned with relating reinforcement (information about which comes from the ventral striatum) with motor output from the dorsal striatum. The conclusions we draw are: (1) the PPTg is an outflow system for the striatum, but also forms a 'subsidiary circuit', returning information to striatal circuitry; in this, the PPTg has an anatomical organisation that resembles that of the substantia nigra. (2) As well as a role in the mediation of REM sleep, cholinergic PPTg neurons have an important role in the waking state, providing feedback into the thalamus and striatum. (3) The precise function of the computations performed on striatal outflow by the PPTg is uncertain. We discuss whether this function is complementary (parallel to other routes of striatal outflow), integrative (modifying other forms of striatal outflow) or both.