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Zhang J, Chen D, Srirangarajan T, Theriault J, Kragel PA, Hartley L, Lee KM, McVeigh K, Wager TD, Wald LL, Satpute AB, Quigley KS, Whitfield-Gabrieli S, Barrett LF, Bianciardi M. Cortical and subcortical mapping of the allostatic-interoceptive system in the human brain: replication and extension with 7 Tesla fMRI. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.20.548178. [PMID: 37546889 PMCID: PMC10401932 DOI: 10.1101/2023.07.20.548178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The brain continuously anticipates the energetic needs of the body and prepares to meet those needs before they arise, a process called allostasis. In support of allostasis, the brain continually models the internal state of the body, a process called interoception. Using published tract-tracing studies in non-human animals as a guide, we previously identified a large-scale system supporting allostasis and interoception in the human brain with functional magnetic resonance imaging (fMRI) at 3 Tesla. In the present study, we replicated and extended this system in humans using 7 Tesla fMRI (N = 91), improving the precision of subgenual and pregenual anterior cingulate topography as well as brainstem nuclei mapping. We verified over 90% of the anatomical connections in the hypothesized allostatic-interoceptive system observed in non-human animal research. We also identified functional connectivity hubs verified in tract-tracing studies but not previously detected using 3 Tesla fMRI. Finally, we demonstrated that individuals with stronger fMRI connectivity between system hubs self-reported greater interoceptive awareness, building on construct validity evidence from our earlier paper. Taken together, these results strengthen evidence for the existence of a whole-brain system supporting interoception in the service of allostasis and we consider the implications for mental and physical health.
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Affiliation(s)
- Jiahe Zhang
- Department of Psychology, Northeastern University, Boston, MA 02115
| | - Danlei Chen
- Department of Psychology, Northeastern University, Boston, MA 02115
| | | | - Jordan Theriault
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02139
| | | | - Ludger Hartley
- Department of Psychology, Northeastern University, Boston, MA 02115
| | - Kent M. Lee
- Department of Psychology, Northeastern University, Boston, MA 02115
| | - Kieran McVeigh
- Department of Psychology, Northeastern University, Boston, MA 02115
| | - Tor D. Wager
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755
| | - Lawrence L. Wald
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02139
| | - Ajay B. Satpute
- Department of Psychology, Northeastern University, Boston, MA 02115
| | - Karen S. Quigley
- Department of Psychology, Northeastern University, Boston, MA 02115
| | | | - Lisa Feldman Barrett
- Department of Psychology, Northeastern University, Boston, MA 02115
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02139
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02139
| | - Marta Bianciardi
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02139
- Division of Sleep Medicine, Harvard University, Boston, MA
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2
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Jones AA, Arble DM. In light of breathing: environmental light is an important modulator of breathing with clinical implications. Front Neurosci 2023; 17:1217799. [PMID: 37521684 PMCID: PMC10373889 DOI: 10.3389/fnins.2023.1217799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
In vertebrate animals, the automatic, rhythmic pattern of breathing is a highly regulated process that can be modulated by various behavioral and physiological factors such as metabolism, sleep-wake state, activity level, and endocrine signaling. Environmental light influences many of these modulating factors both indirectly by organizing daily and seasonal rhythms of behavior and directly through acute changes in neural signaling. While several observations from rodent and human studies suggest that environmental light affects breathing, few have systematically evaluated the underlying mechanisms and clinical relevance of environmental light on the regulation of respiratory behavior. Here, we provide new evidence and discuss the potential neurobiological mechanisms by which light modulates breathing. We conclude that environmental light should be considered, from bench to bedside, as a clinically relevant modulator of respiratory health and disease.
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Lavezzi AM, Mehboob R, Piscioli F, Pusiol T. Involvement of the Superior Colliculus in SIDS Pathogenesis. Biomedicines 2023; 11:1689. [PMID: 37371784 DOI: 10.3390/biomedicines11061689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/25/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
The aim of this study was to investigate the involvement of the mesencephalic superior colliculus (SC) in the pathogenetic mechanism of SIDS, a syndrome frequently ascribed to arousal failure from sleep. We analyzed the brains of 44 infants who died suddenly within the first 7 months of life, among which were 26 infants with SIDS and 18 controls. In-depth neuropathological investigations of serial sections of the midbrain showed the SC layered cytoarchitectural organization already well known in animals, as made up of seven distinct layers, but so far never highlighted in humans, albeit with some differences. In 69% of SIDS cases but never in the controls, we observed alterations of the laminar arrangement of the SC deep layers (precisely, an increased number of polygonal cells invading the superficial layers and an increased presence of intensely stained myelinated fibers). Since it has been demonstrated in experimental studies that the deep layers of the SC exert motor control including that of the head, their developmental disorder could lead to the failure of newborns who are in a prone position to resume regular breathing by moving their heads in the sleep-arousal phase. The SC anomalies highlighted here represent a new step in understanding the pathogenetic process that leads to SIDS.
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Affiliation(s)
- Anna M Lavezzi
- "Lino Rossi" Research Center for the Study and Prevention of Unexpected Perinatal Death and SIDS, Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20122 Milan, Italy
| | - Riffat Mehboob
- Lahore Medical Research Center and LMRC Laboratories, LLP, Lahore 54000, Pakistan
| | - Francesco Piscioli
- Provincial Health Care Services, Institute of Pathology, Santa Maria del Carmine Hospital, 38068 Rovereto, Italy
| | - Teresa Pusiol
- Provincial Health Care Services, Institute of Pathology, Santa Maria del Carmine Hospital, 38068 Rovereto, Italy
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4
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Lynch E, Dempsey B, Saleeba C, Monteiro E, Turner A, Burke PGR, Allen AM, Dampney RAL, Hildreth CM, Cornish JL, Goodchild AK, McMullan S. Descending pathways from the superior colliculus mediating autonomic and respiratory effects associated with orienting behaviour. J Physiol 2022; 600:5311-5332. [PMID: 36271640 PMCID: PMC10107157 DOI: 10.1113/jp283789] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/14/2022] [Indexed: 01/05/2023] Open
Abstract
The ability to discriminate competing external stimuli and initiate contextually appropriate behaviours is a key brain function. Neurons in the deep superior colliculus (dSC) integrate multisensory inputs and activate descending projections to premotor pathways responsible for orienting, attention and defence, behaviours which involve adjustments to respiratory and cardiovascular parameters. However, the neural pathways that subserve the physiological components of orienting are poorly understood. We report that orienting responses to optogenetic dSC stimulation are accompanied by short-latency autonomic, respiratory and electroencephalographic effects in awake rats, closely mimicking those evoked by naturalistic alerting stimuli. Physiological responses were not accompanied by detectable aversion or fear, and persisted under urethane anaesthesia, indicating independence from emotional stress. Anterograde and trans-synaptic viral tracing identified a monosynaptic pathway that links the dSC to spinally projecting neurons in the medullary gigantocellular reticular nucleus (GiA), a key hub for the coordination of orienting and locomotor behaviours. In urethane-anaesthetized animals, sympathoexcitatory and cardiovascular, but not respiratory, responses to dSC stimulation were replicated by optogenetic stimulation of the dSC-GiA terminals, suggesting a likely role for this pathway in mediating the autonomic components of dSC-mediated responses. Similarly, extracellular recordings from putative GiA sympathetic premotor neurons confirmed short-latency excitatory inputs from the dSC. This pathway represents a likely substrate for autonomic components of orienting responses that are mediated by dSC neurons and suggests a mechanism through which physiological and motor components of orienting behaviours may be integrated without the involvement of higher centres that mediate affective components of defensive responses. KEY POINTS: Neurons in the deep superior colliculus (dSC) integrate multimodal sensory signals to elicit context-dependent innate behaviours that are accompanied by stereotypical cardiovascular and respiratory activities. The pathways responsible for mediating the physiological components of colliculus-mediated orienting behaviours are unknown. We show that optogenetic dSC stimulation evokes transient orienting, respiratory and autonomic effects in awake rats which persist under urethane anaesthesia. Anterograde tracing from the dSC identified projections to spinally projecting neurons in the medullary gigantocellular reticular nucleus (GiA). Stimulation of this pathway recapitulated autonomic effects evoked by stimulation of dSC neurons. Electrophysiological recordings from putative GiA sympathetic premotor neurons confirmed short latency excitatory input from dSC neurons. This disynaptic dSC-GiA-spinal sympathoexcitatory pathway may underlie autonomic adjustments to salient environmental cues independent of input from higher centres.
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Affiliation(s)
- Erin Lynch
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Bowen Dempsey
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Christine Saleeba
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Eloise Monteiro
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Anita Turner
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Peter G R Burke
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Andrew M Allen
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Roger A L Dampney
- School of Medical Sciences (Physiology), University of Sydney, Sydney, New South Wales, Australia
| | - Cara M Hildreth
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Jennifer L Cornish
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Ann K Goodchild
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Simon McMullan
- Macquarie Medical School, Faculty of Medicine, Health & Human Sciences, Macquarie University, Sydney, New South Wales, Australia
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5
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Abstract
Breathing is a vital rhythmic motor behavior with a surprisingly broad influence on the brain and body. The apparent simplicity of breathing belies a complex neural control system, the breathing central pattern generator (bCPG), that exhibits diverse operational modes to regulate gas exchange and coordinate breathing with an array of behaviors. In this review, we focus on selected advances in our understanding of the bCPG. At the core of the bCPG is the preBötzinger complex (preBötC), which drives inspiratory rhythm via an unexpectedly sophisticated emergent mechanism. Synchronization dynamics underlying preBötC rhythmogenesis imbue the system with robustness and lability. These dynamics are modulated by inputs from throughout the brain and generate rhythmic, patterned activity that is widely distributed. The connectivity and an emerging literature support a link between breathing, emotion, and cognition that is becoming experimentally tractable. These advances bring great potential for elucidating function and dysfunction in breathing and other mammalian neural circuits.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
| | - Kaiwen Kam
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | | | - Jack L Feldman
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
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6
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Okigawa S, Yamaguchi M, Ito KN, Takeuchi RF, Morimoto N, Osakada F. Cell type- and layer-specific convergence in core and shell neurons of the dorsal lateral geniculate nucleus. J Comp Neurol 2020; 529:2099-2124. [PMID: 33236346 DOI: 10.1002/cne.25075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/27/2022]
Abstract
Over 40 distinct types of retinal ganglion cells (RGCs) generate parallel processing pathways in the visual system. In mice, two subdivisions of the dorsal lateral geniculate nucleus (dLGN), the core and the shell, organize distinct parallel channels to transmit visual information from the retina to the primary visual cortex (V1). To investigate how the dLGN core and shell differentially integrate visual information and other modalities, we mapped synaptic input sources to each dLGN subdivision at the cell-type level with G-deleted rabies viral vectors. The monosynaptic circuit tracing revealed that dLGN core neurons received inputs from alpha-RGCs, Layer 6 neurons of the V1, the superficial and intermediate layers of the superior colliculus (SC), the internal ventral LGN, the lower layer of the external ventral LGN (vLGNe), the intergeniculate leaf, the thalamic reticular nucleus (TRN), and the pretectal nucleus (PT). Conversely, shell neurons received inputs from alpha-RGCs and direction-selective ganglion cells of the retina, Layer 6 neurons of the V1, the superficial layer of the SC, the superficial and lower layers of the vLGNe, the TRN, the PT, and the parabigeminal nucleus. The present study provides anatomical evidence of the cell type- and layer-specific convergence in dLGN core and shell neurons. These findings suggest that dLGN core neurons integrate and process more multimodal information along with visual information than shell neurons and that LGN core and shell neurons integrate different types of information, send their own convergent information to discrete populations of the V1, and differentially contribute to visual perception and behavior.
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Affiliation(s)
- Sayumi Okigawa
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Masahiro Yamaguchi
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Kei N Ito
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Ryosuke F Takeuchi
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Nao Morimoto
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan.,Laboratory of Neural Information Processing, Institute for Advanced Research, Nagoya University, Nagoya, Japan
| | - Fumitaka Osakada
- Laboratory of Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan.,Laboratory of Neural Information Processing, Institute for Advanced Research, Nagoya University, Nagoya, Japan.,Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Nagoya, Japan.,PRESTO/CREST, Japan Science and Technology Agency, Saitama, Japan
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7
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Abstract
Fear is defined as a fundamental emotion promptly arising in the context of threat and when danger is perceived. Fear can be innate or learned. Examples of innate fear include fears that are triggered by predators, pain, heights, rapidly approaching objects, and ancestral threats such as snakes and spiders. Animals and humans detect and respond more rapidly to threatening stimuli than to nonthreatening stimuli in the natural world. The threatening stimuli for most animals are predators, and most predators are themselves prey to other animals. Predatory avoidance is of crucial importance for survival of animals. Although humans are rarely affected by predators, we are constantly challenged by social threats such as a fearful or angry facial expression. This chapter will summarize the current knowledge on brain circuits processing innate fear responses to visual stimuli derived from studies conducted in mice and humans.
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8
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Yang CF, Kim EJ, Callaway EM, Feldman JL. Monosynaptic Projections to Excitatory and Inhibitory preBötzinger Complex Neurons. Front Neuroanat 2020; 14:58. [PMID: 33013329 PMCID: PMC7507425 DOI: 10.3389/fnana.2020.00058] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 08/04/2020] [Indexed: 01/01/2023] Open
Abstract
The key driver of breathing rhythm is the preBötzinger Complex (preBötC) whose activity is modulated by various functional inputs, e.g., volitional, physiological, and emotional. While the preBötC is highly interconnected with other regions of the breathing central pattern generator (bCPG) in the brainstem, there is no data about the direct projections to either excitatory and inhibitory preBötC subpopulations from other elements of the bCPG or from suprapontine regions. Using modified rabies tracing, we identified neurons throughout the brain that send monosynaptic projections to identified excitatory and inhibitory preBötC neurons in mice. Within the brainstem, neurons from sites in the bCPG, including the contralateral preBötC, Bötzinger Complex, the nucleus of the solitary tract (NTS), parafacial region (pF L /pF V ), and parabrachial nuclei (PB), send direct projections to both excitatory and inhibitory preBötC neurons. Suprapontine inputs to the excitatory and inhibitory preBötC neurons include the superior colliculus, red nucleus, amygdala, hypothalamus, and cortex; these projections represent potential direct pathways for volitional, emotional, and physiological control of breathing.
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Affiliation(s)
- Cindy F. Yang
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Euiseok J. Kim
- Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Edward M. Callaway
- Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Jack L. Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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9
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George Zaki Ghali M. Midbrain control of breathing and blood pressure: The role of periaqueductal gray matter and mesencephalic collicular neuronal microcircuit oscillators. Eur J Neurosci 2020; 52:3879-3902. [PMID: 32227408 DOI: 10.1111/ejn.14727] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 02/01/2020] [Accepted: 03/22/2020] [Indexed: 01/12/2023]
Abstract
Neural circuitry residing within the medullary ventral respiratory column nuclei and dorsal respiratory group interact with the Kölliker-Fuse and medial parabrachial nuclei to generate the core breathing rhythm and pattern during resting conditions. Triphasic eupnea consists of inspiratory [I], post-inspiratory [post-I], and late-expiratory [E2] phases. Mesencephalic zones exert modulatory influences upon respiratory rhythm-generating circuitry, sympathetic oscillators, and parasympathetic nuclei. The earliest evidence supporting the existence of midbrain control of breathing derives from studies conducted by Martin and Booker in 1878. These authors demonstrated electrical stimulation of the deep layers of the mesencephalic colliculi in the rabbit augmented ventilation and sequentially elicited chest wall tremors and tetany. Investigations performed during the past several decades would demonstrate stimlation of distributed zones within the midbrain reticular formation elicits starkly disparate effects upon respiratory phase switching. Schmid, Böhmer, and Fallert demonstrated electrical stimulation of the nucleus rubre and emanating axon bundles alternately elicits or inhibits the activity of medullary expiratory- or inspiratory-related units and phrenic nerve discharge with differential latency. A series of studies would later indicate the red nucleus mediates hypoxic ventilatory depression. Periaqueductal gray matter neurons exhibit extensive afferent and efferent interconnectivity with suprabulbar, brainstem, and spinal cord zones aptly positioning these units to modulate breathing, autonomic outflow, nociception locomotion, micturtion, and sexual behavior. Experimental stimulatory activation of the tectal colliculi and periaqueductal gray matter via electrical current or glutamate, D,L-homocysteinic acid, or bicuculline microinjections coordinately modulates neuromotor inspiratory bursting frequency and amplitude and discharge of pre-Bötzinger complex, ventrolateral medullary late-I and post-I, and ventrolateral nucleus tractus solitarius decrementing early-I and augmenting and decrementing late-I neurons, elicits expiratory outflow and vocalization, and blunt the Hering-Breuer reflex in unanesthetzed decerebrate and anesthetized preprations of the cat and rat. Stimulation of the mesencephalic colliuli or dorsal divisions of the PAG potently amplifes renal sympathetic neural efferent activity, dynamic arterial pressure magnitude, and myocardial contraction frequency and elicits various behavioral defense responses. Elicited physiological effects exhibit extensive locoregional heterogeneity and variably enlist requisite contributions from the dorsomedial hypothalamus and/or lateral parabrachial nuclei. Stimulation of the dorsal mesencephalon occasionally elicits dynamic increases of arterial pressure magnitude exhibiting prominent oscillatory variability coherent with phrenic nerve discharge, perhaps by generating intra-neuraxial hysteresis, serving to intermittently deliver blood to organ vascular beds under high pressure in order to prevent organ edema, microcirculatory dysfunction, and downregulation of vascular smooth muscle alpha adrenergic receptors. Chemosensitive mesencephalic caudal raphé units and projections of hypoxia-sensitive units in the caudal hypothalamus to the periaqueductal gray matter may imply the existence of a diencephalo-smesencephalic chemosensitive network modulating breathing and sympathetic discharge.
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Affiliation(s)
- Michael George Zaki Ghali
- Department of Neurological Surgery, Baylor College of Medicine, Houston, Texas.,Department of Neurological Surgery, University of California, San Francisco, California.,Department of Neurological Surgery, Karolinska Institutet, Stockholm, Sweden
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10
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Prater CM, Harris BN, Carr JA. Tectal CRFR1 receptor involvement in avoidance and approach behaviors in the South African clawed frog, Xenopus laevis. Horm Behav 2020; 120:104707. [PMID: 32001211 DOI: 10.1016/j.yhbeh.2020.104707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 10/25/2022]
Abstract
Animals in the wild must balance food intake with vigilance for predators in order to survive. The optic tectum plays an important role in the integration of external (predators) and internal (energy status) cues related to predator defense and prey capture. However, the role of neuromodulators involved in tectal sensorimotor processing is poorly studied. Recently we showed that tectal CRFR1 receptor activation decreases food intake in the South African clawed frog, Xenopus laevis, suggesting that CRF may modulate food intake/predator avoidance tradeoffs. Here we use a behavioral assay modeling food intake and predator avoidance to test the role of CRFR1 receptors and energy status in this tradeoff. We tested the predictions that 1) administering the CRFR1 antagonist NBI-27914 via the optic tecta will increase food intake and feeding-related behaviors in the presence of a predator, and 2) that prior food deprivation, which lowers tectal CRF content, will increase food intake and feeding-related behaviors in the presence of a predator. Pre-treatment with NBI-27914 did not prevent predator-induced reductions in food intake. Predator exposure altered feeding-related behaviors in a predictable manner. Pretreatment with NBI-27914 reduced the response of certain behaviors to a predator but also altered behaviors irrelevant of predator presence. Although 1-wk of food deprivation altered some non-feeding behaviors related to energy conservation strategy, food intake in the presence of a predator was not altered by prior food deprivation. Collectively, our data support a role for tectal CRFR1 in modulating discrete behavioral responses during predator avoidance/foraging tradeoffs.
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Affiliation(s)
- Christine M Prater
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, United States of America.
| | - Breanna N Harris
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, United States of America
| | - James A Carr
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, United States of America
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11
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Oliveira AF, Yonehara K. The Mouse Superior Colliculus as a Model System for Investigating Cell Type-Based Mechanisms of Visual Motor Transformation. Front Neural Circuits 2018; 12:59. [PMID: 30140205 PMCID: PMC6094993 DOI: 10.3389/fncir.2018.00059] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 07/03/2018] [Indexed: 11/13/2022] Open
Abstract
The mouse superior colliculus (SC) is a laminar midbrain structure involved in processing and transforming multimodal sensory stimuli into ethologically relevant behaviors such as escape, defense, and orienting movements. The SC is unique in that the sensory (visual, auditory, and somatosensory) and motor maps are overlaid. In the mouse, the SC receives inputs from more retinal ganglion cells than any other visual area. This makes the mouse SC an ideal model system for understanding how visual signals processed by retinal circuits are used to mediate visually guided behaviors. This Perspective provides an overview of the current understanding of visual motor transformations operated by the mouse SC and discusses the challenges to be overcome when investigating the input–output relationships in single collicular cell types.
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Affiliation(s)
- Ana F Oliveira
- DANDRITE - Danish Research Institute of Translational Neuroscience, Nordic EMBL Partnership for Molecular Medicine, Aarhus, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Keisuke Yonehara
- DANDRITE - Danish Research Institute of Translational Neuroscience, Nordic EMBL Partnership for Molecular Medicine, Aarhus, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
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12
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Divergent midbrain circuits orchestrate escape and freezing responses to looming stimuli in mice. Nat Commun 2018; 9:1232. [PMID: 29581428 PMCID: PMC5964329 DOI: 10.1038/s41467-018-03580-7] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 02/23/2018] [Indexed: 01/30/2023] Open
Abstract
Animals respond to environmental threats, e.g. looming visual stimuli, with innate defensive behaviors such as escape and freezing. The key neural circuits that participate in the generation of such dimorphic defensive behaviors remain unclear. Here we show that the dimorphic behavioral patterns triggered by looming visual stimuli are mediated by parvalbumin-positive (PV+) projection neurons in mouse superior colliculus (SC). Two distinct groups of SC PV+ neurons form divergent pathways to transmit threat-relevant visual signals to neurons in the parabigeminal nucleus (PBGN) and lateral posterior thalamic nucleus (LPTN). Activations of PV+ SC-PBGN and SC-LPTN pathways mimic the dimorphic defensive behaviors. The PBGN and LPTN neurons are co-activated by looming visual stimuli. Bilateral inactivation of either nucleus results in the defensive behavior dominated by the other nucleus. Together, these data suggest that the SC orchestrates dimorphic defensive behaviors through two separate tectofugal pathways that may have interactions. In response to environmental threats, such as visual looming stimuli, mice either freeze or escape. Here the authors demonstrate that these two behaviors are mediated by separate tectofugal pathways formed by parvalbumin-positive neurons in the superior colliculus.
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13
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Direct and indirect nigrofugal projections to the nucleus reticularis pontis caudalis mediate in the motor execution of the acoustic startle reflex. Brain Struct Funct 2018; 223:2733-2751. [DOI: 10.1007/s00429-018-1654-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 03/17/2018] [Indexed: 11/25/2022]
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14
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Hormigo S, Gómez-Nieto R, Sancho C, Herrero-Turrión J, Carro J, López DE, Horta-Júnior JDADCE. Morphological correlates of sex differences in acoustic startle response and prepulse inhibition through projections from locus coeruleus to cochlear root neurons. Brain Struct Funct 2017; 222:3491-3508. [PMID: 28382577 DOI: 10.1007/s00429-017-1415-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/27/2017] [Indexed: 12/18/2022]
Abstract
The noradrenergic locus coeruleus (LC) plays an important role in the promotion and maintenance of arousal and alertness. Our group recently described coerulean projections to cochlear root neurons (CRNs), the first relay of the primary acoustic startle reflex (ASR) circuit. However, the role of the LC in the ASR and its modulation, prepulse inhibition (PPI), is not clear. In this study, we damaged LC neurons and fibers using a highly selective neurotoxin, DSP-4, and then assessed ASR and PPI in male and female rats. Our results showed that ASR amplitude was higher in males at 14 days after DSP-4 injection when compared to pre-administration values and those in the male control group. Such modifications in ASR amplitude did not occur in DSP-4-injected females, which exhibited ASR amplitude within the range of control values. PPI differences between males and females seen in controls were not observed in DSP-4-injected rats for any interstimulus interval tested. DSP-4 injection did not affect ASR and PPI latencies in either the male or the female groups, showing values that were consistent with the sex-related variability observed in control rats. Furthermore, we studied the noradrenergic receptor system in the cochlear nerve root using gene expression analysis. When compared to controls, DSP-4-injected males showed higher levels of expression in all adrenoceptor subtypes; however, DSP-4-injected females showed varied effects depending on the receptor type, with either up-, downregulations, or maintenance of expression levels. Lastly, we determined noradrenaline levels in CRNs and other LC-targeted areas using HPLC assays, and these results correlated with behavioral and adrenoceptor expression changes post DSP-4 injection. Our study supports the participation of LC in ASR and PPI, and contributes toward a better understanding of sex-related differences observed in somatosensory gating paradigms.
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Affiliation(s)
- Sebastian Hormigo
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.
| | - Ricardo Gómez-Nieto
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain.,Department of Cell Biology and Pathology, University of Salamanca, Salamanca, Spain
| | - Consuelo Sancho
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain.,Department of Physiology and Pharmacology, University of Salamanca, Salamanca, Spain
| | - Javier Herrero-Turrión
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain
| | - Juan Carro
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain
| | - Dolores E López
- Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain.,Department of Cell Biology and Pathology, University of Salamanca, Salamanca, Spain
| | - José de Anchieta de Castro E Horta-Júnior
- Department of Anatomy, Institute of Biosciences of Botucatu, Univ. Estadual Paulista (UNESP), Distrito de Rubião Jr., S/N, PO.Box 510, Botucatu, SP, 18618-689, Brazil.
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15
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Silva BA, Gross CT, Gräff J. The neural circuits of innate fear: detection, integration, action, and memorization. ACTA ACUST UNITED AC 2016; 23:544-55. [PMID: 27634145 PMCID: PMC5026211 DOI: 10.1101/lm.042812.116] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 07/19/2016] [Indexed: 12/26/2022]
Abstract
How fear is represented in the brain has generated a lot of research attention, not only because fear increases the chances for survival when appropriately expressed but also because it can lead to anxiety and stress-related disorders when inadequately processed. In this review, we summarize recent progress in the understanding of the neural circuits processing innate fear in rodents. We propose that these circuits are contained within three main functional units in the brain: a detection unit, responsible for gathering sensory information signaling the presence of a threat; an integration unit, responsible for incorporating the various sensory information and recruiting downstream effectors; and an output unit, in charge of initiating appropriate bodily and behavioral responses to the threatful stimulus. In parallel, the experience of innate fear also instructs a learning process leading to the memorization of the fearful event. Interestingly, while the detection, integration, and output units processing acute fear responses to different threats tend to be harbored in distinct brain circuits, memory encoding of these threats seems to rely on a shared learning system.
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Affiliation(s)
- Bianca A Silva
- Laboratory of Neuroepigenetics, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale Lausanne, CH-1015 Lausanne, Switzerland
| | - Cornelius T Gross
- Mouse Biology Unit, European Molecular Biology Laboratory (EMBL), 00015 Monterotondo, Italy
| | - Johannes Gräff
- Laboratory of Neuroepigenetics, Brain Mind Institute, Faculty of Life Sciences, Ecole Polytechnique Fédérale Lausanne, CH-1015 Lausanne, Switzerland
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16
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Müller-Ribeiro FC, Goodchild AK, McMullan S, Fontes MA, Dampney RA. Coordinated autonomic and respiratory responses evoked by alerting stimuli: Role of the midbrain colliculi. Respir Physiol Neurobiol 2016; 226:87-93. [DOI: 10.1016/j.resp.2015.10.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/21/2015] [Accepted: 10/23/2015] [Indexed: 10/22/2022]
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17
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Kron M, Lang M, Adams IT, Sceniak M, Longo F, Katz DM. A BDNF loop-domain mimetic acutely reverses spontaneous apneas and respiratory abnormalities during behavioral arousal in a mouse model of Rett syndrome. Dis Model Mech 2015; 7:1047-55. [PMID: 25147297 PMCID: PMC4142725 DOI: 10.1242/dmm.016030] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Reduced levels of brain-derived neurotrophic factor (BDNF) are thought to contribute to the pathophysiology of Rett syndrome (RTT), a severe neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). In Mecp2 mutant mice, BDNF deficits have been associated with breathing abnormalities, a core feature of RTT, as well as with synaptic hyperexcitability within the brainstem respiratory network. Application of BDNF can reverse hyperexcitability in acute brainstem slices from Mecp2-null mice, suggesting that therapies targeting BDNF or its receptor, TrkB, could be effective at acute reversal of respiratory abnormalities in RTT. Therefore, we examined the ability of LM22A-4, a small-molecule BDNF loop-domain mimetic and TrkB partial agonist, to modulate synaptic excitability within respiratory cell groups in the brainstem nucleus tractus solitarius (nTS) and to acutely reverse abnormalities in breathing at rest and during behavioral arousal in Mecp2 mutants. Patch-clamp recordings in Mecp2-null brainstem slices demonstrated that LM22A-4 decreases excitability at primary afferent synapses in the nTS by reducing the amplitude of evoked excitatory postsynaptic currents and the frequency of spontaneous and miniature excitatory postsynaptic currents. In vivo, acute treatment of Mecp2-null and -heterozygous mutants with LM22A-4 completely eliminated spontaneous apneas in resting animals, without sedation. Moreover, we demonstrate that respiratory dysregulation during behavioral arousal, a feature of human RTT, is also reversed in Mecp2 mutants by acute treatment with LM22A-4. Together, these data support the hypothesis that reduced BDNF signaling and respiratory dysfunction in RTT are linked, and establish the proof-of-concept that treatment with a small-molecule structural mimetic of a BDNF loop domain and a TrkB partial agonist can acutely reverse abnormal breathing at rest and in response to behavioral arousal in symptomatic RTT mice.
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Affiliation(s)
- Miriam Kron
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ian T Adams
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Michael Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Frank Longo
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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18
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Sceniak MP, Lang M, Enomoto AC, James Howell C, Hermes DJ, Katz DM. Mechanisms of Functional Hypoconnectivity in the Medial Prefrontal Cortex of Mecp2 Null Mice. Cereb Cortex 2015; 26:1938-1956. [PMID: 25662825 DOI: 10.1093/cercor/bhv002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Frontal cortical dysfunction is thought to contribute to cognitive and behavioral features of autism spectrum disorders; however, underlying mechanisms are poorly understood. The present study sought to define how loss of Mecp2, the gene mutated in Rett syndrome (RTT), disrupts function in the murine medial prefrontal cortex (mPFC) using acute brain slices and behavioral testing. Compared with wildtype, pyramidal neurons in the Mecp2 null mPFC exhibit significant reductions in excitatory postsynaptic currents, the duration of excitatory UP-states, evoked population activity, and the ratio of NMDA:AMPA currents, as well as an increase in the relative fraction of NR2B currents. These functional changes are associated with reductions in the density of excitatory dendritic spines, the ratio of vesicular glutamate to GABA transporters and GluN1 expression. In contrast to recent reports on circuit defects in other brain regions, we observed no effect of Mecp2 loss on inhibitory synaptic currents or expression of the inhibitory marker parvalbumin. Consistent with mPFC hypofunction, Mecp2 nulls exhibit respiratory dysregulation in response to behavioral arousal. Our data highlight functional hypoconnectivity in the mPFC as a potential substrate for behavioral disruption in RTT and other disorders associated with reduced expression of Mecp2 in frontal cortical regions.
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Affiliation(s)
- Michael P Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Addison C Enomoto
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - C James Howell
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Douglas J Hermes
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Müller-Ribeiro FCF, Dampney RAL, McMullan S, Fontes MAP, Goodchild AK. Disinhibition of the midbrain colliculi unmasks coordinated autonomic, respiratory, and somatomotor responses to auditory and visual stimuli. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1025-35. [DOI: 10.1152/ajpregu.00165.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The midbrain superior and inferior colliculi have critical roles in generating coordinated orienting or defensive behavioral responses to environmental stimuli, and it has been proposed that neurons within the colliculi can also generate appropriate cardiovascular and respiratory responses to support such behavioral responses. We have previously shown that activation of neurons within a circumscribed region in the deep layers of the superior colliculus and in the central and external nuclei of the inferior colliculus can evoke a response characterized by intense and highly synchronized bursts of renal sympathetic nerve activity and phrenic nerve activity. In this study, we tested the hypothesis that, under conditions in which collicular neurons are disinhibited, coordinated cardiovascular, somatomotor, and respiratory responses can be evoked by natural environmental stimuli. In response to natural auditory, visual, or somatosensory stimuli, powerful synchronized increases in sympathetic, respiratory, and somatomotor activity were generated following blockade of GABAA receptors in a specific region in the midbrain colliculi of anesthetized rats, but not under control conditions. Such responses still occurred after removal of most of the forebrain, including the amygdala and hypothalamus, indicating that the essential pathways mediating these coordinated responses were located within the brain stem. The temporal relationships between the different outputs suggest that they are driven by a common population of “command neurons” within the colliculi.
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Affiliation(s)
- Flávia C. F. Müller-Ribeiro
- Australian School of Advanced Medicine, Macquarie University, New South Wales, Australia; and
- Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil; and
| | - Roger A. L. Dampney
- School of Medical Sciences (Physiology) and Bosch Institute, University of Sydney, New South Wales, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, New South Wales, Australia; and
| | - Marco A. P. Fontes
- Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil; and
| | - Ann K. Goodchild
- Australian School of Advanced Medicine, Macquarie University, New South Wales, Australia; and
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20
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Dutta A, Gutfreund Y. Saliency mapping in the optic tectum and its relationship to habituation. Front Integr Neurosci 2014; 8:1. [PMID: 24474908 PMCID: PMC3893637 DOI: 10.3389/fnint.2014.00001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 01/02/2014] [Indexed: 12/02/2022] Open
Abstract
Habituation of the orienting response has long served as a model system for studying fundamental psychological phenomena such as learning, attention, decisions, and surprise. In this article, we review an emerging hypothesis that the evolutionary role of the superior colliculus (SC) in mammals or its homolog in birds, the optic tectum (OT), is to select the most salient target and send this information to the appropriate brain regions to control the body and brain orienting responses. Recent studies have begun to reveal mechanisms of how saliency is computed in the OT/SC, demonstrating a striking similarity between mammals and birds. The saliency of a target can be determined by how different it is from the surrounding objects, by how different it is from its history (that is habituation) and by how relevant it is for the task at hand. Here, we will first review evidence, mostly from primates and barn owls, that all three types of saliency computations are linked in the OT/SC. We will then focus more on neural adaptation in the OT and its possible link to temporal saliency and habituation.
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Affiliation(s)
- Arkadeb Dutta
- Rappaport Family Institute for Research in the Medical Sciences, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology Haifa, Israel
| | - Yoram Gutfreund
- Rappaport Family Institute for Research in the Medical Sciences, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology Haifa, Israel
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21
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Role of dorsolateral periaqueductal grey in the coordinated regulation of cardiovascular and respiratory function. Auton Neurosci 2013; 175:17-25. [DOI: 10.1016/j.autneu.2012.12.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 12/18/2012] [Accepted: 12/26/2012] [Indexed: 02/07/2023]
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22
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Iigaya K, Müller-Ribeiro FCDF, Horiuchi J, McDowall LM, Nalivaiko E, Fontes MAP, Dampney RAL. Synchronized activation of sympathetic vasomotor, cardiac, and respiratory outputs by neurons in the midbrain colliculi. Am J Physiol Regul Integr Comp Physiol 2012; 303:R599-610. [DOI: 10.1152/ajpregu.00205.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The superior and inferior colliculi are believed to generate immediate and highly coordinated defensive behavioral responses to threatening visual and auditory stimuli. Activation of neurons in the superior and inferior colliculi have been shown to evoke increases in cardiovascular and respiratory activity, which may be components of more generalized stereotyped behavioral responses. In this study, we examined the possibility that there are “command neurons” within the colliculi that can simultaneously drive sympathetic and respiratory outputs. In anesthetized rats, microinjections of bicuculline (a GABAA receptor antagonist) into sites within a circumscribed region in the deep layers of the superior colliculus and in the central and external nuclei of the inferior colliculus evoked a response characterized by intense and highly synchronized bursts of renal sympathetic nerve activity (RSNA) and phrenic nerve activity (PNA). Each burst of RSNA had a duration of ∼300–400 ms and occurred slightly later (peak to peak latency of 41 ± 8 ms) than the corresponding burst of PNA. The bursts of RSNA and PNA were also accompanied by transient increases in arterial pressure and, in most cases, heart rate. Synchronized bursts of RSNA and PNA were also evoked after neuromuscular blockade, artificial ventilation, and vagotomy and so were not dependent on afferent feedback from the lungs. We propose that the synchronized sympathetic-respiratory responses are driven by a common population of neurons, which may normally be activated by an acute threatening stimulus.
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Affiliation(s)
- Kamon Iigaya
- School of Medical Sciences (Physiology) and Bosch Institute for Biomedical Research, University of Sydney, Australia
| | - Flávia Camargos de Figueirêdo Müller-Ribeiro
- School of Medical Sciences (Physiology) and Bosch Institute for Biomedical Research, University of Sydney, Australia
- Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil
| | - Jouji Horiuchi
- School of Medical Sciences (Physiology) and Bosch Institute for Biomedical Research, University of Sydney, Australia
- Department of Biomedical Engineering, Toyo University, Saitama, Japan; and
| | - Lachlan M. McDowall
- School of Medical Sciences (Physiology) and Bosch Institute for Biomedical Research, University of Sydney, Australia
| | - Eugene Nalivaiko
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Marco A. P. Fontes
- Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil
| | - Roger A. L. Dampney
- School of Medical Sciences (Physiology) and Bosch Institute for Biomedical Research, University of Sydney, Australia
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23
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Hahn JD, Swanson LW. Connections of the lateral hypothalamic area juxtadorsomedial region in the male rat. J Comp Neurol 2012; 520:1831-90. [PMID: 22488503 DOI: 10.1002/cne.23064] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The connections of the lateral hypothalamic area juxtadorsomedial region (LHAjd) were investigated in a series of pathway-tracing experiments involving iontophoretic co-injection of the tracers Phaseolus vulgaris-leucoagglutinin (PHA-L; for outputs) and cholera toxin B subunit (CTB; for inputs). Results revealed that the LHAjd has connections with some 318 distinct gray matter regions encompassing all four subsystems-motor, sensory, cognitive, and behavioral state-included in a basic structure-function network model of the nervous system. Integration of these subsystems is necessary for the coordination and control of emotion and behavior, and in that regard the connections of the LHAjd indicate that it may have a prominent role. Furthermore, the LHAjd connections, together with the connections of other LHA differentiations studied similarly to date, indicate a distinct topographic organization that suggests each LHA differentiation has specifically differing degrees of involvement in the control of multiple behaviors. For the LHAjd, its involvement to a high degree in the control of defensive behavior, and to a lesser degree in the control of other behaviors, including ingestive and reproductive, is suggested. Moreover, the connections of the LHAjd suggest that its possible role in the control of these behaviors may be very broad in scope because they involve the somatic, neuroendocrine, and autonomic divisions of the nervous system. In addition, we suggest that connections between LHA differentiations may provide, at the level of the hypothalamus, a neuronal substrate for the coordinated control of multiple themes in the behavioral repertoire.
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Affiliation(s)
- Joel D Hahn
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-2520, USA.
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Periaqueductal gray matter modulates the hypercapnic ventilatory response. Pflugers Arch 2012; 464:155-66. [PMID: 22665049 DOI: 10.1007/s00424-012-1119-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 05/16/2012] [Accepted: 05/22/2012] [Indexed: 01/15/2023]
Abstract
The periaqueductal gray (PAG) is a midbrain structure directly involved in the modulation of defensive behaviors. It has direct projections to several central nuclei that are involved in cardiorespiratory control. Although PAG stimulation is known to elicit respiratory responses, the role of the PAG in the CO(2)-drive to breathe is still unknown. The present study assessed the effect of chemical lesion of the dorsolateral and dorsomedial and ventrolateral/lateral PAG (dlPAG, dmPAG, and vPAG, respectively) on cardiorespiratory and thermal responses to hypercapnia. Ibotenic acid (IBO) or vehicle (PBS, Sham group) was injected into the dlPAG, dmPAG, or vPAG of male Wistar rats. Rats with lesions outside the dlPAG, dmPAG, or vPAG were considered as negative controls (NC). Pulmonary ventilation (VE: ), mean arterial pressure (MAP), heart rate (HR), and body temperature (Tb) were measured in unanesthetized rats during normocapnia and hypercapnic exposure (5, 15, 30 min, 7 % CO(2)). IBO lesioning of the dlPAG/dmPAG caused 31 % and 26.5 % reductions of the respiratory response to CO(2) (1,094.3 ± 115 mL/kg/min) compared with Sham (1,589.5 ± 88.1 mL/kg/min) and NC groups (1,488.2 ± 47.7 mL/kg/min), respectively. IBO lesioning of the vPAG caused 26.6 % and 21 % reductions of CO(2) hyperpnea (1,215.3 ± 108.6 mL/kg/min) compared with Sham (1,657.3 ± 173.9 mL/kg/min) and NC groups (1,537.6 ± 59.3). Basal VE: , MAP, HR, and Tb were not affected by dlPAG, dmPAG, or vPAG lesioning. The results suggest that dlPAG, dmPAG, and vPAG modulate hypercapnic ventilatory responses in rats but do not affect MAP, HR, or Tb regulation in resting conditions or during hypercapnia.
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Abstract
Visually guided collision avoidance is critical for the survival of many animals. The execution of successful collision-avoidance behaviors requires accurate processing of approaching threats by the visual system and signaling of threat characteristics to motor circuits to execute appropriate motor programs in a timely manner. Consequently, visually guided collision avoidance offers an excellent model with which to study the neural mechanisms of sensory-motor integration in the context of a natural behavior. Neurons that selectively respond to approaching threats and brain areas processing them have been characterized across many species. In locusts in particular, the underlying sensory and motor processes have been analyzed in great detail: These animals possess an identified neuron, called the LGMD, that responds selectively to approaching threats and conveys that information through a second identified neuron, the DCMD, to motor centers, generating escape jumps. A combination of behavioral and in vivo electrophysiological experiments has unraveled many of the cellular and network mechanisms underlying this behavior.
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Affiliation(s)
- Haleh Fotowat
- Department of Biology, McGill University, Montreal, Quebec, H3A-1B1, Canada.
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26
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Deolindo MV, Pelosi GG, Busnardo C, Resstel LBM, Corrêa FMA. Cardiovascular effects of acetylcholine microinjection into the ventrolateral and dorsal periaqueductal gray of rats. Brain Res 2011; 1371:74-81. [DOI: 10.1016/j.brainres.2010.11.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 11/11/2010] [Accepted: 11/13/2010] [Indexed: 02/08/2023]
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27
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Netser S, Ohayon S, Gutfreund Y. Multiple Manifestations of Microstimulation in the Optic Tectum: Eye Movements, Pupil Dilations, and Sensory Priming. J Neurophysiol 2010; 104:108-18. [DOI: 10.1152/jn.01142.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well established that the optic tectum (or its mammalian homologue, the superior colliculus) is involved in directing gaze toward salient stimuli. However, salient stimuli typically induce orienting responses beyond gaze shifts. The role of the optic tectum in generating responses such as pupil dilation, galvanic responses, or covert shifts is not clear. In the present work, we studied the effects of microstimulation in the optic tectum of the barn owl ( Tyto alba) on pupil diameter and on eye shifts. Experiments were conducted in lightly anesthetized head-restrained barn owls. We report that low-level microstimulation in the deep layers of the optic tectum readily induced pupil dilation responses (PDRs), as well as small eye movements. Electrically evoked PDRs, similar to acoustically evoked PDRs, were long-lasting and habituated to repeated stimuli. We further show that microstimulation in the external nucleus of the inferior colliculus also induced PDRs. Finally, in experiments in which tectal microstimulations were coupled with acoustic stimuli, we show a tendency of the microstimulation to enhance pupil responses and eye shifts to previously habituated acoustic stimuli. The enhancement was dependent on the site of stimulation in the tectal spatial map; responses to sounds with spatial cues that matched the site of stimulation were more enhanced compared with sounds with spatial cues that did not match. These results suggest that the optic tectum is directly involved in autonomic orienting reflexes as well as in gaze shifts, highlighting the central role of the optic tectum in mediating the body responses to salient stimuli.
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Affiliation(s)
- Shai Netser
- The Department of Physiology and Biophysics, The Rappaport Faculty of Medicine and Research Institute, The Technion–Israel Institute of Technology, Haifa, Israel; and
| | - Shay Ohayon
- Computation and Neural Systems, California Institute of Technology, Pasadena, California
| | - Yoram Gutfreund
- The Department of Physiology and Biophysics, The Rappaport Faculty of Medicine and Research Institute, The Technion–Israel Institute of Technology, Haifa, Israel; and
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28
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Garcia Pelosi G, Fiacadori Tavares R, Barros Parron Fernandes K, Morgan Aguiar Corrêa F. Cardiovascular effects of noradrenaline microinjection into the medial part of the superior colliculus of unanesthetized rats. Brain Res 2009; 1290:21-7. [PMID: 19615348 DOI: 10.1016/j.brainres.2009.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 07/02/2009] [Accepted: 07/02/2009] [Indexed: 10/20/2022]
Abstract
The superior colliculus (SC) is a mesencephalic area involved in the mediation of defensive movements associated with cardiovascular changes. Noradrenaline (NA) is a neurotransmitter with an important role in central cardiovascular regulation exerted by several structures of the central nervous system. Although noradrenergic nerve terminals have been observed in the SC, there are no reports on the effects of local NA injection into this area. Taking this into consideration, we studied the cardiovascular effects of NA microinjection into the SC of unanesthetized rats. Microinjection of NA into the SC evoked a dose-dependent blood pressure increase and a heart rate decrease in unanesthetized rats. The pressor response to NA was not modified by intravenous pretreatment with the vasopressin v(1)-receptor antagonist dTyr(CH(2))(5)(Me)AVP, indicating a lack of vasopressin involvement in the response mediation. The effect of NA microinjection into the SC was blocked by intravenous pretreatment with the ganglionic blocker pentolinium, indicating its mediation by the sympathetic nervous system. Although the pressor response to NA was not affected by adrenal demedullation, the accompanying bradycardia was potentiated, suggesting some involvement of the sympathoadrenal system in the cardiovascular response to NA microinjection into the SC. In summary, results indicate that stimulation of noradrenergic receptors in the SC causes cardiovascular responses which are mediated by activation of both neural and adrenal sympathetic nervous system components.
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Affiliation(s)
- Gislaine Garcia Pelosi
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes 3900, 14040-900, Ribeirão Preto, São Paulo, Brazil.
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Thompson S, Lupi D, Hankins MW, Peirson SN, Foster RG. The effects of rod and cone loss on the photic regulation of locomotor activity and heart rate. Eur J Neurosci 2008; 28:724-9. [PMID: 18702692 PMCID: PMC3001038 DOI: 10.1111/j.1460-9568.2008.06388.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Behavioral responses to light indirectly affect cardiovascular output, but in anesthetized rodents a direct effect of light on heart rate has also been described. Both the basis for this response and the contribution of rods, cones and melanopsin-based photosensitive retinal ganglion cells (pRGCs) remains unknown. To understand how light acutely regulates heart rate we studied responses to light in mice lacking all rod and cone photoreceptors (rd/rd cl ) along with wild-type controls. Our initial experiments delivered light to anesthetized mice at Zeitgeber time (ZT)16 (4 h after lights off, mid-activity phase) and produced an increase in heart rate in wild-type mice, but not in rd/rd cl animals. By contrast, parallel experiments in freely-moving mice demonstrated that light exposure at this time suppressed heart rate and activity in both genotypes. Because of the effects of anesthesia, all subsequent studies were conducted in freely-moving animals. The effects of light were also assessed at ZT6 (mid-rest phase). At this timepoint, wild-type mice showed an irradiance-dependent increase in heart rate and activity. By contrast, rd/rd cl mice failed to show any modulation of heart rate or activity, even at very high irradiances. Increases in heart rate preceded increases in locomotor activity and remained elevated when locomotor activity ceased, suggesting that these two responses are at least partially uncoupled. Collectively, our results show an acute and phase-dependent effect of light on cardiovascular output in mice. Surprisingly, this irradiance detection response is dependent upon rod and cone photoreceptors, with no apparent contribution from melanopsin pRGCs.
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Affiliation(s)
- Stewart Thompson
- Nuffield Laboratory of Ophthalmology, The John Radcliffe Hospital, Headley Way, University of Oxford, Roosevelt Drive, Oxford OX3 9DU, UK
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Pelosi GG, Resstel LBM, Corrêa FMA. Dorsal periaqueductal gray area synapses modulate baroreflex in unanesthetized rats. Auton Neurosci 2007; 131:70-6. [PMID: 16914391 DOI: 10.1016/j.autneu.2006.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 07/04/2006] [Accepted: 07/10/2006] [Indexed: 10/24/2022]
Abstract
The dorsal portion of the periaqueductal gray area (dPAG) is involved in behavioral and cardiovascular control. We report the effect of acute and reversible dPAG blockade by local microinjection of either lidocaine or CoCl2 on the baroreflex response of unanesthetized rats. Acute and reversible blockade evoked by lidocaine microinjection into the dPAG did not affect the bradycardic response to mean arterial pressure (MAP) increases evoked by i.v. infusion of phenylephrine. However, lidocaine increased baroreflex gain and tachycardic reflex in response to MAP decreases evoked by i.v. infusion of sodium nitroprusside, thus suggesting an action on the sympathetic component of the baroreflex. The effects of dPAG synapses blockade caused by CoCl2 were similar to those observed after lidocaine microinjection. CoCl2 microinjection also increased baroreflex gain and tachycardiac responses to MAP decreases without affecting the parasympathetic baroreflex component. In conclusion, our data point to a dPAG tonic inhibitory involvement in baroreflex control, specifically modulating the sympathetic baroreflex component. Temporary dPAG ablation by local microinjection of lidocaine increased the sympathetic baroreflex component. Because CoCl2 microinjection had similar effects on the baroreflex, this modulation involves local synaptic neurotransmission within the dPAG.
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Affiliation(s)
- G G Pelosi
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes 3900, 14040-900, Ribeirão Preto, São Paulo, Brazil
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Bittencourt AS, Nakamura-Palacios EM, Mauad H, Tufik S, Schenberg LC. Organization of electrically and chemically evoked defensive behaviors within the deeper collicular layers as compared to the periaqueductal gray matter of the rat. Neuroscience 2005; 133:873-92. [PMID: 15916856 DOI: 10.1016/j.neuroscience.2005.03.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 03/04/2005] [Accepted: 03/11/2005] [Indexed: 10/25/2022]
Abstract
Stimulation of the periaqueductal gray matter (PAG) and the deeper layers of superior colliculus (SC) produces both freezing (tense immobility) and flight (trotting, galloping and jumping) behaviors along with exophthalmus (fully opened bulging eyes) and, less often, micturition and defecation. The topography of these behaviors within the distinct layers of SC remains unclear. Therefore, this study compared the defensive repertoire of intermediate (ILSC) and deep (DLSC) layers of SC to those of dorsolateral periaqueductal gray matter (DLPAG) and lateral periaqueductal gray matter (LPAG) [Neuroscience 125 (2004) 71]. Electrical stimulation was carried out through intensity- (0-70 microA) and frequency-varying (0-130 Hz) pulses. Chemical stimulation employed a slow microinfusion of N-methyl-d-aspartic acid (NMDA, 0-2.3 nmol, 0.5 nmol/min). Probability curves of intensity-, frequency- and NMDA-evoked behaviors, as well as the unbiased estimates of median stimuli, were obtained by threshold logistic analysis. Compared with the PAG, the most important differences were the lack of frequency-evoked jumping in both layers of SC and the lack of NMDA-evoked galloping in the ILSC. Moreover, although galloping and jumping were also elicited by NMDA stimulation of DLSC, effective doses were about three times higher than those of DLPAG, suggesting the spreading of the injectate to the latter structure. In contrast, exophthalmus, immobility and trotting were evoked throughout the tectum structures. However, whatever the response and kind of stimulus, the lowest thresholds were always found in the DLPAG and the highest ones in the ILSC. Besides, neither the appetitive, nor the offensive, muricide or male reproductive behaviors were produced by any kind of stimulus in the presence of appropriate targets. Accordingly, the present data suggest that the deeper layers of SC are most likely involved in the increased attentiveness (exophthalmus, immobility) or restlessness (trotting) behaviors that herald a full-blown flight reaction (galloping, jumping) mediated in the PAG.
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Affiliation(s)
- A S Bittencourt
- Departamento de Ciências Fisiológicas, Centro Biomédico, Edifício do Programa de Pós-Graduação em Ciências Fisiológicas, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468 (Maruípe), 29043-125 Vitória, ES, Brazil
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Schenberg LC, Póvoa RMF, Costa ALP, Caldellas AV, Tufik S, Bittencourt AS. Functional specializations within the tectum defense systems of the rat. Neurosci Biobehav Rev 2005; 29:1279-98. [PMID: 16087233 DOI: 10.1016/j.neubiorev.2005.05.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 05/03/2005] [Accepted: 05/03/2005] [Indexed: 01/29/2023]
Abstract
Here we review the differential contribution of the periaqueductal gray matter (PAG) and superior colliculus (SC) to the generation of rat defensive behaviors. The results of studies involving sine-wave and rectangular pulse electrical stimulation and chemical (NMDA) stimulation are summarized. Stimulation of SC and PAG produced freezing and flight behaviors along with exophthalmus (fully opened bulged eyes), micturition and defecation. The columnar organization of the PAG was evident in the results obtained. Defecation was elicited primarily by lateral PAG stimulation, while the remaining defensive behaviors were similarly elicited by lateral and dorsolateral PAG stimulation, although with the lowest thresholds in the dorsolateral column. Conversely, the ventrolateral PAG did not appear to participate in unconditioned defensive behaviors, which were only elicited by high intensity stimulation likely to encroach on adjacent regions. In the SC, the most important differences relative to the PAG were the lack of stimulation-evoked jumping in both intermediate and deep layers, and of NMDA-evoked galloping in intermediate layers. Therefore, we conclude that the SC may be only involved in the increased attentiveness (exophthalmus, immobility) and restlessness (trotting) of prey species exposed to the cues of a nearby predator. These responses may be distinct from the full-blown flight reaction that is mediated by the dorsolateral and lateral PAG. However, other evidences suggest the possible influences of stimulation schedule, environment dimensions and rat strain in determining outcomes. Overall our results suggest a dynamically organized representation of defensive behaviors in the midbrain tectum.
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Affiliation(s)
- L C Schenberg
- Departamento de Ciências Fisiológicas--Centro Biomédico (Edifício do Programa de Pós-Graduação em Ciências Fisiológicas), Universidade Federal do Espírito Santo, Av. Marechal Campos 1468 (Maruípe), 29043-125, Vitória, ES, Brazil.
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Frost BJ, Sun H. Chapter 2 The biological bases of time-to-collision computation. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s0166-4115(04)80004-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Woo MA, Macey PM, Fonarow GC, Hamilton MA, Harper RM. Regional brain gray matter loss in heart failure. J Appl Physiol (1985) 2003; 95:677-84. [PMID: 12716866 DOI: 10.1152/japplphysiol.00101.2003] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heart failure (HF) patients exhibit enhanced sympathetic tone, aberrant responses to blood pressure challenges, and sleep-related breathing disorders, suggesting that the syndrome is accompanied by central neural deficits. We assessed regional gray matter volumes over the entire brain in nine HF patients (51 +/- 10 yr; left ventricular ejection fraction 0.27 +/- 0.06; six men) and 27 healthy controls (46 +/- 12 yr; 22 men) using T1-weighted magnetic resonance imaging to evaluate potential neural damage. Regional volumes were evaluated by using voxel-based morphometry while controlling for age, gender, and handedness. HF patients showed significant and largely lateralized gray matter loss in autonomic and respiratory-related areas as well as regions not classically associated with such control, including the insula and basal ganglia, right cingulate gyrus, parahippocampal/fusiform gyrus, dorsal midbrain extending to the posterior and medial thalamus, ventral and superior lateral frontal cortex, bilateral cerebellar quadrangular lobules and right fastigial and neighboring nuclei, and bilateral deep parietal and lateral parietal-occipital cortex. Areas of gray matter loss may contribute to inappropriate cognitive, autonomic, and breathing regulation in HF.
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Affiliation(s)
- Mary A Woo
- School of Nursing, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095-1763, USA
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Mana S, Chevalier G. The fine organization of nigro-collicular channels with additional observations of their relationships with acetylcholinesterase in the rat. Neuroscience 2002; 106:357-74. [PMID: 11566506 DOI: 10.1016/s0306-4522(01)00283-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The nigro-collicular pathway that links the basal ganglia to the sensorimotor layers of superior colliculus plays a crucial role in promoting orienting behaviors. This connection originating in the pars reticulata and lateralis of the substantia nigra has been shown in rat and cat to be topographically organized. In rat, a functional compartmentalization of the substantia nigra has also been shown reflecting that of the striatum. In light of this, we reinvestigated the topographical arrangement of the nigro-collicular pathway by examining the innervation of each nigral functional zone. We performed small injections of either biocytin or wheatgerm agglutinin conjugated with horseradish peroxidase restricted to identified somatic, visual and auditory nigral zones. Frontally cut sections showed that innervations provided by the three main nigral zones form a mosaic of complementary domains stratified from the stratum opticum to the ventral part of the intermediate collicular layers, with the somatic afferents sandwiched between the visual and the auditory ones. When reconstructed from semi-horizontal sections, nigral innervations organized in the form of a honeycomb-like array composed of 100 cylindrical modules covering three-quarters of the collicular surface. Such a modular architecture is reminiscent of the acetylcholinesterase lattice we previously described in rat intermediate collicular layers. In the enzyme lattice, the surroundings of the cylindrical modules are composed of a mosaic of dense and diffuse enzyme subdomains. Thus, we compared the distribution of the overall nigral projection and of its constituent channels with the acetylcholinesterase lattice. The procedure combined axonal labelling with histochemistry on single sections for acetylcholinesterase activity. The results demonstrate that the overall nigral projection overlaps the acetylcholinesterase lattice and its constituent channels converge with either the dense or the diffuse enzyme subdomains. The stereometric arrangement of the nigro-collicular pathway is suggestive of an architecture promoting the selection of collicular motor programs for different classes of orienting behavior.
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Affiliation(s)
- S Mana
- Université René Descartes, Laboratoire de Neurosciences Comportementales, Centre Universitaire de Boulogne, 71 avenue Edouard Vaillant, 92774 Boulogne Billancourt, France
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Cheng ZB, Kobayashi M, Nosaka S. Effects of optic tract stimulation on baroreflex vagal bradycardia in rats. Clin Exp Pharmacol Physiol 2001; 28:721-8. [PMID: 11553030 DOI: 10.1046/j.1440-1681.2001.03509.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Arterial baroreflexes are suppressed in stressful conditions. Intense visual stimuli can cause a threatening sensation and produce defensive reactions. 2. The present study was designed to determine whether and how electrical stimulation of the optic tract (OT) affects arterial baroreflexes, especially the heart rate component, baroreflex vagal bradycardia (BVB), in rats. In chloralose- urethane anaesthetized, beta-adrenoceptor-blocked rats, BVB was evoked by electrical stimulation of the aortic depressor nerve. 3. Electrical stimulation of the OT was found to not only increase blood pressure and heart rate, but also to inhibit BVB. To determine whether these responses were mediated by the lateral genticulate body and/or the superior colliculus, which are major target sites to which the OT projects, each was activated with electrical and chemical stimulation. 4. The lateral genticulate body did not respond to either electrical or chemical stimulation, whereas the superior colliculus increased blood pressure and heart rate while suppressing BVB following electrical stimulation. Essentially similar responses were observed following microinjection of the GABA antagonist bicuculline methiodide. 5. Optic tract-induced inhibition of BVB was abolished by bilateral destruction of the superior colliculus. Furthermore, this inhibition was also largely attenuated by destruction of the midbrain periaqueductal grey (PAG). 6. In conclusion, electrical stimulation of the OT increases blood pressure, heart rate and inhibits BVB. These responses are not mediated by the lateral genticulate body but are mediated by the superior colliculus. The PAG may participate in the subsequent mediation of the responses to electrical stimulation of the OT and the OT-induced inhibition of BVB may contribute to expression of a light-induced defence reaction.
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Affiliation(s)
- Z B Cheng
- Department of Physiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
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Abstract
The superior colliculus (SC) is one of the most ancient regions of the vertebrate central sensory system. In this hub afferents from several sensory pathways converge, and an extensive range of neural circuits enable primary sensory processing, multi-sensory integration and the generation of motor commands for orientation behaviours. The SC has a laminar structure and is usually considered in two parts; the superficial visual layers and the deep multi-modal/motor layers. Neurones in the superficial layers integrate visual information from the retina, cortex and other sources, while the deep layers draw together data from many cortical and sub-cortical sensory areas, including the superficial layers, to generate motor commands. Functional studies in anaesthetized subjects and in slice preparations have used pharmacological tools to probe some of the SC's interacting circuits. The studies reviewed here reveal important roles for ionotropic glutamate receptors in the mediation of sensory inputs to the SC and in transmission between the superficial and deep layers. N-methyl-D-aspartate receptors appear to have special responsibility for the temporal matching of retinal and cortical activity in the superficial layers and for the integration of multiple sensory data-streams in the deep layers. Sensory responses are shaped by intrinsic inhibitory mechanisms mediated by GABA(A) and GABA(B) receptors and influenced by nicotinic acetylcholine receptors. These sensory and motor-command activities of SC neurones are modulated by levels of arousal through extrinsic connections containing GABA, serotonin and other transmitters. It is possible to naturally stimulate many of the SC's sensory and non-sensory inputs either independently or simultaneously and this brain area is an ideal location in which to study: (a) interactions between inputs from the same sensory system; (b) the integration of inputs from several sensory systems; and (c) the influence of non-sensory systems on sensory processing.
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Affiliation(s)
- K E Binns
- Department of Visual Science, Institute of Ophthalmology, University College, London, UK
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Sampaio KN, Mauad H, Biancardi VC, Barros JL, Amaral FT, Schenberg LC, Vasquez EC. Cardiovascular changes following acute and chronic chemical lesions of the dorsal periaqueductal gray in conscious rats. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1999; 76:99-107. [PMID: 10412833 DOI: 10.1016/s0165-1838(99)00015-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study was carried out to investigate the effects of chemical lesions of dorsal periaqueductal gray (DPAG) on resting arterial pressure (AP) and heart rate (HR) as well as on cardiac baroreflex of conscious normotensive rats. Lesions were performed by bilateral microinjections of 150 mM NMDA into the DPAG (DPAG-lesion group). Controls were similarly injected with 165 mM NaCl (DPAG-sham group). Animals with chronic lesions confined only to the superior colliculus (SC-lesion group) were also used as controls of DPAG-lesion. Cardiovascular parameters were recorded 1 or 7 days after the microinjections of NMDA in acute and chronic groups, respectively. Cardiac baroreflex was assessed by measuring the HR responses to the intravenous injection of phenylephrine or sodium nitroprusside. Baroreflex was estimated by sigmoidal curve fitting of HR responses. An increased baroreflex gain was observed in chronic DPAG-lesion rats compared to both DPAG-sham (p < 0.01) and SC-lesion (p < 0.05) chronic groups. The chronic DPAG-lesion group showed also an elevation of both the tachycardia (p < 0.05) and bradycardia (p < 0.01) plateaus compared to chronic DPAG-sham rats, while the SC-lesion group showed an elevation of the bradycardia plateau only (p < 0.01). Similar results on baroreflex function were observed following acute lesion of the DPAG, i.e. an increase in baroreflex gain (p < 0.01) and the elevation of both tachycardia (p < 0.05) and bradycardia plateaus (p < 0.01) compared to the acute DPAG-sham group. Resting AP and HR did not differ among the chronic groups. In contrast, the acute lesion of the DPAG produced a reduction in AP (p < 0.01) accompanied by an increase in HR (p < 0.01). The present data suggest that the DPAG is involved in the tonic and reflex control of AP and HR in conscious rats. In addition, the SC seems to contribute to the baroreflex cardioinhibition.
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Affiliation(s)
- K N Sampaio
- Department of Physiological Sciences, Biomedical Center, Federal University of Espirito Santo, Vitoria, Brazil
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D'Amico M, Di Filippo C, Rossi F. Endothelin-1 in the superior colliculus of rats induces depressor responses due to peripheral hemodynamic changes. Life Sci 1998; 63:PL39-43. [PMID: 9698053 DOI: 10.1016/s0024-3205(98)00264-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microinjection of endothelin-1 (ET-1; 10 pmol) into the superficial layer of the superior colliculus caused systemic and regional hemodynamic changes, as measured by injection of radioactive microspheres at the peak of the hypotensive effect of endothelin-1. Endothelin-1 decreased total peripheral resistance by 39 +/- 2% (n=5); the vascular resistances were decreased in the spleen, the mesentery, the large intestine and the small intestine. Moreover, we found that in consequence of the increased fraction of cardiac output received by the above organs, decreases in vascular resistances were associated with increases in blood flows in them. Interestingly, ET-1 also decreased the vascular resistances and increased the total blood flows in the kidneys. The haemodynamic changes induced by injection of endothelin-1 to the superior colliculus were associated with significant decreases in the mean arterial blood pressure (37 +/- 4 mmHg, n=6) and no changes in heart rate. Exogenous ET-1, therefore, within the SC decreases blood pressure due to peripheral hemodynamic changes.
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Affiliation(s)
- M D'Amico
- Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, II University of Naples, Italy
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D'Amico M, Di Filippo C, Rossi F. Depressor responses to endothelin-1 into the superior colliculus of rats: predominant role of endothelin ET(B) receptors. Eur J Pharmacol 1998; 347:71-5. [PMID: 9650850 DOI: 10.1016/s0014-2999(98)00205-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We used in vitro autoradiography to identify the endothelin-1 receptor subtype(s) in the superficial gray layer of the superior colliculus of rats. These studies showed dense binding of (3-[125I]iodotyrosyl13)-[Ala11,15]Ac-endothelin-1-(6-2 1) (BQ3020) (for endothelin ETB receptors), while tissues incubated with [125I]( N-(hexahydro-1-azepinyl)carbonyl)L-Leu(1-Me)D-Trp-D-Tyr (PD151242) (for endothelin ETA receptors) had low binding. In addition, we examined the effects of the endothelin receptor antagonists, (R)-2-[(R)-2-[(S)-2-[[1-hexahydro-1H-azepinyl)]carbonyl]amino-4-++ +methylpentanoyl]-amino-3-(2-pyridyl)propionic acid (FR139317) (endothelin ETA receptor-selective), (+)-(1S,2R,3S)-3-(2-carboxymethoxy-4-methoxyphenyl)-1-(3,4-methylenediox yphenyl)-5-(prop-1-yloxy)indane-2-carboxylic acid (SB209670) (endothelin ETA/ETB receptor non-selective) and N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-metLeu-D-1-m ethoxycarbonylTrp-D-Nle (BQ-788) (endothelin ETB receptor-selective antagonist) on the responses following administration of endothelin-1 into the superficial layer of the superior colliculus. Endothelin-1 microinjected into this nucleus causes decreases in blood pressure (control, 109 +/- 6 mmHg, n = 6; endothelin-1, 72 +/- 5 mmHg, n = 6). These effects were greatly reduced by pre-administration into the superior colliculus of BQ-788 (5 nmol/rat) or SB209670 (3 nmol/rat) (94 +/- 5 and 98 +/- 6%, respectively) but were not affected by FR139317 (5 nmol/rat) (6 +/- 3%). Therefore, together with autoradiography, our functional data showed that endothelin ETB receptors are the predominant mediators of depressor responses induced by endothelin-1 injected into the superior colliculus of the rat.
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Affiliation(s)
- M D'Amico
- Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, 2nd University of Naples, Italy
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D'Amico M, Rossi F, Warner TD. Regulation of blood pressure by L-arginine-nitric oxide pathway within the superior colliculus of rats. Eur J Pharmacol 1997; 328:65-7. [PMID: 9203570 DOI: 10.1016/s0014-2999(97)83029-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Injection into the superior colliculus of anaesthetised rats of the nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME; 1 micromol), but not its inactive enantiomer N(omega)-nitro-D-arginine methyl ester (D-NAME; 1 micromol), significantly (P < 0.01) increased the mean arterial blood pressure. Injection to the superior colliculus of L-arginine (L-Arg; 1 micromol), the substrate for NO synthase, significantly (P < 0.01) lessened the pressor effect of L-NAME, while D-arginine (D-Arg; 1 micromol) did not affect it. L-Arg (7.5 micromol), but not D-Arg (7.5 micromol) administered at the peak of the pressor response to L-NAME (1 micromol) also partially reversed this pressor response (P < 0.05). These data would suggest that endogenously produced NO acts within the superior colliculus to modulate the arterial blood pressure.
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Affiliation(s)
- M D'Amico
- Institute of Pharmacology and Toxicology, 2nd University of Naples, Italy
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43
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D'Amico M, Rossi F, Warner TD. Cardiovascular responses induced by injection of endothelin-1 into the superior colliculus of rats. Eur J Pharmacol 1996; 316:245-7. [PMID: 8982693 DOI: 10.1016/s0014-2999(96)00778-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Microinjection of endothelin-1 (1-10-100 pmol) into the superficial layer of the superior colliculus of anaesthetised rats caused dose-dependent decreases in blood pressure. This is unlikely to be a non-specific effect, for angiotensin II (1 nmol) caused increases in blood pressure. Injection of endothelin-1 (10 pmol) into the superior colliculus also caused falls in renal blood flow as measured by an ultrasonic flow probe. Decreases in blood pressure and falls in renal blood flow induced by injection of endothelin-1 into the superior colliculus were unaffected by bilateral vagotomy suggesting that attenuations in the activity of the sympathetic nervous system were involved in these events.
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Affiliation(s)
- M D'Amico
- Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, 2nd University of Naples, Italy
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Abstract
Much progress has been made the understanding of endogenous pain-controlling systems. Recently, new concepts and ideas which are derived from neurobiology, chaos research and from research on learning and memory have been introduced into pain research and shed further light on the organization and function of endogenous antinociception. These most recent developments will be reviewed here. Three principles of endogenous antinociception have been identified, as follows. (1) Supraspinal descending inhibition: the patterns of neuronal activity in diencephalon, brainstem and spinal cord during antinociceptive stimulation in midbrain periaqueductal gray (PAG) or medullary nucleus raphe magnus have now been mapped on the cellular level, using the c-Fos technique. Results demonstrate that characteristic activity patterns result within and outside the PAG when stimulating at its various subdivisions. The descending systems may not only depress mean discharge rates of nociceptive spinal dorsal horn neurons, but also may modify harmonic oscillations and nonlinear dynamics (dimensionality) of discharges. (2) Propriospinal, heterosegmental inhibition: antinociceptive, heterosegmental interneurons exist which may be activated by noxious stimulation or by supraspinal descending pathways. (3) Segmental spinal inhibition: a robust long-term depression of primary afferent neurotransmission in A delta fibers has been identified in superficial spinal dorsal horn which may underlie long-lasting antinociception by afferent stimulation, e.g. by physical therapy or acupuncture.
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Affiliation(s)
- J Sandkühler
- II. Physiologisches Institut, Universität Heidelberg, Germany.
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45
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King SM, Shehab S, Dean P, Redgrave P. Differential expression of fos-like immunoreactivity in the descending projections of superior colliculus after electrical stimulation in the rat. Behav Brain Res 1996; 78:131-45. [PMID: 8864045 DOI: 10.1016/0166-4328(95)00241-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In rodent, there is evidence that the orienting behaviour elicited by direct stimulation of the superior colliculus (SC) is partly mediated by contralateral descending projections, while avoidance-type behaviour is associated with ipsilateral descending projections. However, the identity of target structures in the brainstem which mediate these different behavioural responses is unknown. The c-fos immediate early gene is expressed polysynaptically in neurons in response to a wide range of extracellular stimuli, and hence has been proposed as a technique for mapping functional pathways. The purpose of this study was, therefore, to use the c-fos technique to investigate the functional specificity of brainstem regions which are innervated by the two main descending projections of the SC. Patterns of fos-like immunoreactivity (FLI) were observed throughout the brainstem following electrical stimulation of the SC in Urethane-anaesthetized rats. Previously, the electrical stimulation had been shown to elicit either approach-like or avoidance-like movement. The main results of this experiment were; (i) animals in which the stimulation elicited defensive behaviour had elevated levels of immunostaining in specific terminal areas of the ipsilateral descending projections, e.g. the ventrolateral midbrain/pontine reticular formation, the cuneiform area and rostral periaqueductal grey; (ii) there was no FLI expression in any of the terminal areas of the crossed descending projection, even in animals where the electrical stimulation elicited approach. Control experiments showed that the lack of expression in the crossed descending pathway was not due to the restricted range of stimulation parameters used in the main study, or to the effects of the anaesthetic. In conclusion, this experiment was able to identify likely substrates for the mediation of defensive reactions elicited by tectal stimulation. However, given the total lack of expression in a pathway which is known to be activated, it also provides further evidence that c-fos cannot simply be used as a high resolution neuronal activity marker for mapping functional pathways.
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Affiliation(s)
- S M King
- Department of Psychology, University of Sheffield, UK.
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Shehab S, Simkins M, Dean P, Redgrave P. The dorsal midbrain anticonvulsant zone--I. Effects of locally administered excitatory amino acids or bicuculline on maximal electroshock seizures. Neuroscience 1995; 65:671-9. [PMID: 7609869 DOI: 10.1016/0306-4522(94)00515-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Microinjections of bicuculline methiodide into the dorsal midbrain anticonvulsant zone, a region which includes the caudal deep layers of the superior colliculus, the adjacent mesencephalic reticular formation and the intercollicular nucleus, suppress tonic hindlimb extension induced by maximal electroshock. The purpose of the present experiments was to establish the most effective and convenient method for eliciting anticonvulsant properties from the dorsal midbrain using the electroshock model of epilepsy. A comparison of different injections of excitatory amino acids and bicuculline into the dorsal midbrain of the rat showed: (i) injections of kainate suppressed hindlimb extension but only at substantially larger doses (i.e. 200-400 pmol) than 50 pmol of bicuculline, which produced generally superior effects; (ii) quisqualate provided only weak protection against tonic seizures at doses that produced neurotoxic effects (2-40 nmol); (iii) N-methyl-D-aspartate was ineffective at doses which produced mild clonic seizure in their own right (2-4 nmol) and also produced some evidence of neurotoxicity; (iv) the suppression of hindlimb extension by bicuculline was dose related, and the lowest bilateral dose for producing reliable suppression was 50 pmol/400 nl per side; and (v) a unilateral injection of 100 pmol/400 nl also reliably suppressed hindlimb extension. The latter finding had important implications for the design and interpretation of the following lesion study. Injections of bicuculline into the dorsal midbrain also produced defence-like behavioural responses that included running and biting; the intensity of these responses correlated with the suppression of hindlimb extension.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Shehab
- Department of Anatomy, University of Glasgow, U.K
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47
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Shehab S, Dean P, Redgrave P. The dorsal midbrain anticonvulsant zone--II. Efferent connections revealed by the anterograde transport of wheatgerm agglutinin-horseradish peroxidase from injections centred on the intercollicular area in the rat. Neuroscience 1995; 65:681-95. [PMID: 7541903 DOI: 10.1016/0306-4522(94)00516-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Activation of the dorsal midbrain has a powerful anticonvulsant effect in the maximal electroshock model of epilepsy. The suppression of tonic seizures can be obtained most reliably from an area centred on the intercollicular nucleus overlapping into the deep layers of the superior colliculus and adjacent mesencephalic reticular formation. As part of a series of investigations to identify neural mechanisms responsible for mediating the anticonvulsant properties of the dorsal midbrain, the present study provides an anatomical description of the efferent projections of this region. Small amounts of wheatgerm agglutinin-horseradish peroxidase (10-30 nl of a 1% solution) were injected into the intercollicular nucleus and surrounding tissue. The resulting anterograde transport of the tracer was plotted on a set of standard atlas sections. Four major output pathways were identified: (i) an ipsilateral descending projection which had terminations in the microcellular tegmental nucleus, lateral and ventral pontine reticular nucleus pars oralis, ventrolateral tegmental nucleus, ventral and caudal pontine reticular nucleus pars caudalis, raphe magnus nucleus and the gigantocellular nucleus; (ii) a contralateral descending projection which for the most part targeted the same brainstem structures but with weaker terminal labelling; (iii) a projection to the contralateral dorsal midbrain with comparatively weak terminal label in the contralateral superior colliculus, intercollicular nucleus, periaqueductal gray, mesencephalic reticular formation and cuneiform area; (iv) ipsilateral ascending pathway with terminations in the red nucleus, zona incerta, peripeduncular area, parafascicular nucleus, lateral hypothalamus, parts of the pretectum and caudal thalamus. At a general level the dorsal midbrain anticonvulsant zone shares its major output projections and efferent targets with at least one of its near neighbours, including the superior colliculus, periaqueductal gray, the cuneiform nucleus and pedunculopontine nucleus. The possibility that anticonvulsant properties of the intercollicular area can simply be attributed to a unique set of efferent projections is therefore not supported by the anatomy.
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Affiliation(s)
- S Shehab
- Department of Anatomy, University of Glasgow, U.K
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Westby GW, Collinson C, Redgrave P, Dean P. Opposing excitatory and inhibitory influences from the cerebellum and basal ganglia converge on the superior colliculus: an electrophysiological investigation in the rat. Eur J Neurosci 1994; 6:1335-42. [PMID: 7981875 DOI: 10.1111/j.1460-9568.1994.tb00324.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We recently showed (Westby et al., Eur. J. Neurosci., 5, 1378-1388, 1993) that the cerebellar interpositus nucleus is a source of excitatory drive for a population of spontaneously active neurons in the lateral intermediate layers of the contralateral superior colliculus. Anatomical and physiological studies have shown that this region of the colliculus contains cells of origin of the crossed descending tectoreticulospinal tract and receives GABAergic input from the ipsilateral basal ganglia. In the present study we tested the hypothesis that the same neurons receiving excitatory drive from the cerebellum also receive tonic inhibitory input from the substantia nigra pars reticulata. From a sample of 73 spontaneously active collicular cells we found that in 53% the firing rate was suppressed by GABA microinjection into the contralateral deep cerebellar nuclei; a further 15% showed a frequency increase. Of the collicular cells identified as receiving excitatory cerebellar input, 85% were found to be disinhibited by nigral GABA microinjection. The remainder were all inhibited by nigral GABA. These data show that the main excitatory influence from the cerebellum and the main inhibitory influence from the substantia nigra converge on at least one population of spontaneously active cells in the lateral intermediate layers of the superior colliculus. This finding is discussed in relation to the possible function of these spontaneous cells in movement control and nociception.
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Affiliation(s)
- G W Westby
- Department of Psychology, Sheffield University, UK
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Schenberg LC, Vasquez EC, da Costa MB. Cardiac baroreflex dynamics during the defence reaction in freely moving rats. Brain Res 1993; 621:50-8. [PMID: 8221073 DOI: 10.1016/0006-8993(93)90296-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To determine the extent of baroreceptor reflex involvement in the cardiovascular changes observed during electrically induced defence reaction, the mean arterial blood pressure (MBP) and heart rate (HR) of conscious intact or sinoaortic baroreceptor denervated (SAD) rats were continuously recorded from indwelling cannulae during a 1-min period of electrical stimulation of the mesencephalic tectum. Electrical stimulation produced stimulus intensity-dependent behaviours including freezing at lower intensities and flight at higher intensities. The cardiovascular responses in intact rats were dependent on both the intensity and duration of the stimulus. A linear increase in MBP was observed with increasing stimulus intensities. However, while a slight bradycardia was observed during the freezing behaviour, a marked tachycardia occurred during flight. Simultaneous increases of MBP and HR were seen throughout the first 15 s of the flight response, after which the HR rapidly fell to baseline levels, whereas the MBP remained at a hypertensive plateau until the end of the stimulus. The baroreflex HR curve showed a parallel shift to the left during the first half of the freezing period, being fully reset 40 s after that. So, while the baroreflex gain remained unchanged, the reflex set point was lowered during the freezing stage of the defence reaction. The experiments with SAD rats corroborated the above data. The baroreceptor denervation reversed the freezing bradycardia to tachycardia. Moreover, the denervation potentiated the flight tachycardia and prevented its later reset. MBP responses of baroreceptor denervated rats did not differ from the sham-operated group. The sustained hypertension, thus, appears to be mediated by mechanisms other than the mere baroreceptor reflex deactivation. (ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L C Schenberg
- Department of Physiological Sciences, Federal University of Espirito Santo, Vitória, Brazil
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50
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Redgrave P, Westby GW, Dean P. Functional architecture of rodent superior colliculus: relevance of multiple output channels. PROGRESS IN BRAIN RESEARCH 1993; 95:69-77. [PMID: 8493354 DOI: 10.1016/s0079-6123(08)60358-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- P Redgrave
- Department of Psychology, University of Sheffield, U.K
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