Tonic Inhibition

Cross references:     Cerebellum Tonic Inhibition    Behavioral Disinhibition   
GABA/Glycine Inhibition     Lamprey GABA   Initiation of Locomotion in Lampreys    
Inhibition of Locomotion in Lampreys          Locomotion Sequence    


Searching PubMed for "tonic inhibition" yielded 4981 references: 
http://www.ncbi.nlm.nih.gov/pubmed/?term=tonic+inhibition   

Searching PubMed for "gaba tonic inhibition" yielded 1206 references:   
http://www.ncbi.nlm.nih.gov/pubmed/?term=gaba+tonic+inhibition  
    Am I really going to review all 1206 references?  GABA tonic inhibition is a very important factor in my hypothetical understanding of behavior, but that's an awful lot of references.   
    Note:  During the course of the review of these references, the number of them rose from 1206 to 1240. 


1980 1234<1240  
Nucleus accumbens to globus pallidus GABA projection: electrophysiological and iontophoretic investigations.  
http://www.ncbi.nlm.nih.gov/pubmed/7370763   
    "Fifty-three per cent of all globus pallidus neurons examined had increased spontaneous firing frequencies following the iontophoretic administration of picrotoxin alone. This is indicative of the removal of a tonic GABA input onto these neurons."    
    See:   Locomotion Sequence  for full Abstract, Related citations and Cited by's. 

        Picrotoxin  (Wiki)       
       
https://en.wikipedia.org/wiki/Picrotoxin   
            "
It acts as a non-competitive channel blocker for the GABAA receptor chloride channels.[3]"  


1981 1228<1240
Evidence for a tonic GABAergic control of serotonin neurons in the median raphe nucleus.
http://www.ncbi.nlm.nih.gov/pubmed/7470888   
    "The results provide evidence of a tonic inhibition by GABA of 5-HT neuronal activity in the median raphe nucleus; this inhibitory effect is potentiated by benzodiazepines."
    See:  GABA/Glycine Inhibition for full Abstract, Related citations and Cited by's. 


1984 1210<1240
Synaptic organization of the basal ganglia: an electroanatomical approach in the rat.  
http://www.ncbi.nlm.nih.gov/pubmed/?term=6094126   
   "The findings reported clearly establish that SNr exerts a tonic inhibitory influence on its collicular and thalamic targets. It is suggested that the striatum may achieve a complex-spatial pattern of facilitation in a large spectrum of structures related to ocular and cephalic motor activity by inhibiting the inhibitory nigrothalamic and nigrocollicular branched neurons.
    See: 
Substantia Nigra pars Reticulata   for Related citations. 


1988 10<13
Synaptic organization of the striatum   
http://www.ncbi.nlm.nih.gov/pubmed/3069970   
    "The striatum, the main component of the basal ganglia, is composed of mainly one type of neuron, the so-called medium spiny neuron. This neuron cell type, which constitutes over 90% of striatal neurons, is the major output neuron of the striatum.  Combined ultrastructural neuroanatomical methods have elucidated the organization of afferent connectivity to these neurons.  
    The major physiologic function of striatal efferent activity appears to be inhibition of tonically active GABAergic neurons in the globus pallidus and substantia nigra pars reticulata."   
    See:  Medium Spiny Neurons 
    My comment
"
inhibition of tonically active GABAergic neurons" should cause excitation. 


1992    1075<1206 
Tonic inhibition of striatal dopamine transmission: effects of benzodiazepine and GABAA receptor antagonists on extracellular dopamine levels.   
http://www.ncbi.nlm.nih.gov/pubmed/1337302       
    "The results suggest that GABA may play a tonic inhibitory role with regard to striatal DA transmission."    
    See:  Dopamine for full Abstract, Related citations and a single Cited by. 


1994     
Rat substantia nigra pars reticulata neurones are tonically inhibited via GABAA, but not GABAB, receptors in vitro,
    "We conclude that the firing rate of SNr neurones is under tonic inhibition by GABA in vitro, which can be relieved by antagonists of GABAA, but not GABAB receptors, and enhanced by blockade of GABA reuptake. The source of this GABA tone is likely to be from recurrent axon collaterals of SNr neurones themselves."      
    See:  Substantia Nigra   for full Abstract, Related citations and Cited by's.   


1996    (from a different search)
Neural networks for vertebrate locomotion     
http://www.ncbi.nlm.nih.gov/pubmed/8533066      
    See:  GABA/Glycine Inhibition  . 
 

1998   958<1206 
Segregation of different GABAA receptors to synaptic and extrasynaptic membranes of cerebellar granule cells.  
http://www.ncbi.nlm.nih.gov/pubmed/9464994   
    "Two types of GABAA receptor-mediated inhibition (phasic and tonic) have been described in cerebellar granule cells, although these cells receive GABAergic input only from a single cell type, the Golgi cell. ... The exclusive extrasynaptic presence of the delta subunit-containing receptors, together with their kinetic properties, suggests that tonic inhibition could be mediated mainly by extrasynaptic alpha6beta2/3delta receptors, whereas phasic inhibition is attributable to the activation of synaptic alpha1beta2/3gamma2, alpha6beta2/3gamma2, and alpha1alpha6beta2/3gamma2 receptors."    
    See:  GABA Gate  for full Abstract, Related citations, Cited by's and Free Full Text. 


1999    916<1206 
GABAergic control of rat substantia nigra dopaminergic neurons: role of globus pallidus and substantia nigra pars reticulata. 
http://www.ncbi.nlm.nih.gov/pubmed/10199615      
    "These data suggest that globus pallidus exerts significant control over the firing rate and pattern of substantia nigra dopaminergic neurons through a disynaptic pathway involving nigral pars reticulata GABAergic neurons and that at least one important way in which local application of bicuculline induces burst firing of dopaminergic neurons is by disinhibition of this tonic inhibitory input."    
    See: 
Substantia Nigra pars Compacta   for full Abstract, Related citations and Cited by's. 


1999    914<1206 
GABA(A) and GABA(B) antagonists differentially affect the firing pattern of substantia nigra dopaminergic neurons in vivo. 
    "These data demonstrate that dopaminergic neurons in vivo are under tonic GABAergic inhibition."
    See:  Substantia Nigra  for full Abstract, Related citations and Cited by's.     
 

2004    743<1206 
Defense reaction mediated by NMDA mechanisms in the inferior colliculus is modulated by GABAergic nigro-collicular pathways.  
http://www.ncbi.nlm.nih.gov/pubmed/14746929          
    "Electrical stimulation of the inferior colliculus (IC) causes a behavioral activation together with autonomic responses similar to fear reactions to threatening situations. GABAergic mechanisms exert a tonic inhibitory control on the neural substrates of aversion in the IC  ...  Additionally, a reduction of the inhibitory control exerted by nigrocollicular GABAergic neurons  ... ."     
    See:  Fear  for full Abstract, Related citations and Cited by's.   


2004    740<1206 
Mechanisms and significance of reduced activity and responsiveness in resting frog tadpoles.   
http://www.ncbi.nlm.nih.gov/pubmed/14978054       
    "This leads to tonic GABA inhibition that reduces tadpole activity and responses, and leads to fewer attacks by predators."  
    See:  GABA/Glycine Inhibition  for full Abstract, Related citations, Cited by's and Full Free Text.  


2004   739<1206 
Brainstem control of activity and responsiveness in resting frog tadpoles: tonic inhibition.    
    "We provide evidence supporting the hypothesis that long-term reduced responsiveness in attached tadpoles results from tonic activity in the reticulospinal GABAergic pathway mediating the stopping response."  
    See:   Reticulospinal Transmission   for full Abstract, Related citations and Cited by's.   


2004    716<1206 
Clustering of extrasynaptic GABA(A) receptors modulates tonic inhibition in cultured hippocampal neurons.   
    "Tonic inhibition plays a crucial role in regulating neuronal excitability because it sets the threshold for action potential generation and integrates excitatory signals. Tonic currents are known to be largely mediated by extrasynaptic gamma-aminobutyric acid type A (GABA(A)) receptors that are persistently activated by submicromolar concentrations of ambient GABA."     
    See:  GABA/Glycine Inhibition  for full Abstract, Related citations, Cited by's and Full Free Text.  
 

2005    691<1206 
Variations on an inhibitory theme: phasic and tonic activation of GABA(A) receptors.     
http://www.ncbi.nlm.nih.gov/pubmed/15738957       
    "However, there is growing evidence that low concentrations of ambient GABA can persistently activate certain subtypes of GABA(A) receptor, which are often remote from synapses, to generate a 'tonic' conductance."  
    See:   GABA Gate  for full Abstract, Related citations and Cited by's. 


2005   
84<349
Mechanisms for selection of basic motor programs--roles for the striatum and pallidum
.
http://www.ncbi.nlm.nih.gov/pubmed/15935487
     "The nervous system contains a toolbox of motor programs in the brainstem and spinal cord--that is, neuronal networks designed to handle the basic motor repertoire required for survival, including locomotion, posture, eye movements, breathing, chewing, swallowing and expression of emotions. The neural mechanisms responsible for selecting which motor program should be recruited at a given instant are the focus of this review. Motor programs are kept under tonic inhibition by GABAergic pallidal neurons (the output nuclei of the basal ganglia). The motor programs can be relieved from pallidal inhibition through activation of striatal neurons at the input stage of the basal ganglia. It is argued that the striatum has a prominent role in selecting which motor program should be called into action."  
   
My comment
As far as I can remember, this is the first Grillner reference which considers anything more anterior than the reticular system.  I'll probably be coming back to this. 
    Summary
"
motor programs can be relieved from pallidal inhibition through activation of striatal neurons"  


2006    639<1206   
Graded response to GABA by native extrasynaptic GABA receptors.  
http://www.ncbi.nlm.nih.gov/pubmed/16573642       
    "GABA is the main inhibitory neurotransmitter in the mammalian CNS. GABA in the brain is commonly associated with a fast, point-to-point form of signalling called synaptic transmission (phasic inhibition), but there is growing evidence that GABA participates in another, slower and more diffuse form of signalling often referred to as tonic inhibition."    
    See:  GABA   for full Abstract, Related citations and Cited by's. 


2006    632>1206 
GABAergic mechanisms in regulating the activity state of substantia nigra pars reticulata neurons   
http://www.ncbi.nlm.nih.gov/pubmed/16713116     
    "Substantia nigra reticulata is the major output structure of the basal ganglia involved in somatosensory integration and organization of movement. While previous work in vitro and in anesthetized animal preparations suggests that these neurons are autoactive and points to GABA as a primary input regulating their activity, single-unit recording coupled with iontophoresis was used in awake, unrestrained rats to further clarify the role of tonic and phasic GABA input in maintenance and fluctuations of substantia nigra reticulata neuronal activity under physiologically relevant conditions."     
    See: 
Substantia Nigra pars Reticulata  for full Abstract and Related Citations.   


2006    607<1206   
Tonic GABA(A) receptor-mediated currents in human brain 
    "GABA(A) receptors can mediate both phasic (synaptic) and tonic (extrasynaptic) forms of inhibition. It has been proposed that tonic inhibition plays a critical part in controlling neuronal and network excitability. ... Here we show that tonic currents can be recorded from human tissue obtained from patients undergoing temporal lobectomies."
    See:  Human Neurotransmitters   for full Abstract, Related citations and Cited by's.   
  

2007     (from a different search)  
Descending GABAergic projections to the mesencephalic locomotor region in the lamprey Petromyzon marinus.     
http://www.ncbi.nlm.nih.gov/pubmed/17226790      
    "These results suggest that the GABAergic projections to the MLR modulate the activity of MLR neurons, which would be inhibited by GABA at rest."  

    See:  Lamprey GABA


2007    (from a different search)  
GABA distribution in lamprey is phylogenetically conserved.  
http://www.ncbi.nlm.nih.gov/pubmed/17480011  
    "These results suggest that the GABAergic projections to the MLR modulate the activity of MLR neurons, which would be inhibited by GABA at rest." 
    See:  Lamprey GABA  .  


2008    540<1206 
Regulation of excitability by extrasynaptic GABA(A) receptors. 
    "Not only are GABA(A) receptors activated transiently by GABA released at synapses, but high affinity, extrasynaptic GABA(A) receptors are also activated by ambient, extracellular GABA as a more persistent form of signalling (often termed tonic inhibition)."  
    See:  GABA Gate for full Abstract, Related citations and Cited by's. 


2008    460<1206 
Tonic GABAergic inhibition of sympathetic preganglionic neurons: a novel substrate for sympathetic control.   
    "The sympathetic tone is primarily defined by the level of activity of the sympathetic preganglionic neurons. We report a novel inhibitory influence on sympathetic activity, that of tonic GABAergic inhibition which could have a profound global effect on sympathetic outflow."    
    See:  Sympathetic Nervous System  for full Abstract, Related citations, Cited by's, and Full Free Text.     


2008
Diencephalic locomotor region in the lamprey--afferents and efferent control.

    "
These findings suggest that GABAergic projections provide tonic inhibition that once turned off can release locomotion."      
    See:   Diencephaloreticular Transmission  for full Abstract, Related citations, Cited by's and Free Full Text


2009    406<1206 
Extrasynaptic GABAA receptors: form, pharmacology, and function.   
    "Whereas synaptic GABA(A) receptors underlie classical "phasic" GABA(A) receptor-mediated inhibition (inhibitory postsynaptic currents), tonic GABA(A) receptor-mediated inhibition results from the activation of extrasynaptic receptors by low concentrations of ambient GABA."     
    See:   GABA Gate   for full Abstract, Related citations, Cited by's and  Free PMC Article  . 


2010   383<1206 
Developmental regulation and neuroprotective effects of striatal tonic GABAA currents. 
    "Striatal neurons are known to express GABA(A) receptor subunits that underlie both phasic and tonic inhibition. Striatal projection neurons, or medium spiny neurons (MSNs), are divided into two classes: MSNs containing the dopamine D1 receptor (D1-MSNs) form the direct pathway to the substantia nigra and facilitate movement while MSNs expressing the dopamine D2 receptor (D2-MSNs) form the pallidal pathway that inhibits movement."  
    See:  Striatum  for full Abstract, Related citations, Cited by's and  Free PMC Article


2011   280<1206 
Intrinsic and integrative properties of substantia nigra pars reticulata neurons.  

    "The GABA projection neurons of the substantia nigra pars reticulata (SNr) are output neurons for the basal ganglia and thus critical for movement control. Their most striking neurophysiological feature is sustained, spontaneous high frequency spike firing. ...  SNr GABA neurons have a higher density of I(NaT), contributing to the faster rise and larger amplitude of action potentials, compared with the slow-spiking dopamine neurons. I(NaT) also recovers from inactivation more quickly in SNr GABA neurons than in nigral dopamine neurons."    
    See:  Substantia Nigra  for full Abstract, Related citations, Cited by's and  Free PMC Article


2012   256<1206 
Extrasynaptic GABA(A) receptors: their function in the CNS and implications for disease. 

    "Over the past two decades, research has identified extrasynaptic GABA(A) receptor populations that enable neurons to sense the low ambient GABA concentrations present in the extracellular space in order to generate a form of tonic inhibition not previously considered in studies of neuronal excitability."  
    See:  GABA Gate for full Abstract, Related citations, Cited by's and  Free PMC Article


2012      (from a different search)
Evolution of the basal ganglia: dual-output pathways conserved throughout vertebrate phylogeny.   
    "GABAergic SNr projection neurons are tonically active and project to the thalamus and brainstem motor areas."    
    See:   
Substantia Nigra   .   


2016   
A thalamic input to the nucleus accumbens mediates opiate dependence : Nature   
http://www.nature.com/nature/journal/v530/n7589/full/nature16954.html 
    See:   Accumbens Input


2013   185<1206 
Extrasynaptic GABA(A) receptors in the brainstem and spinal cord: structure and function. 

    "This review highlights past and present developments in the field of extrasynaptic GABAA receptors and emphasizes their subunit containing distribution and physiological role in the spinal cord."     
    See:  GABA Gate  for full Abstract, Related citations and a single Cited by. 


2013    178<1206
GABAB Receptors Regulate Extrasynaptic GABAA Receptors.  

    "These results demonstrate for the first time a postsynaptic crosstalk between GABA(B) and GABA(A) receptors."     
    See:   GABA Metabotropic Receptor    for full Abstract, Related citations, Cited by's
and 
Free PMC Article


2013    160<1206 
Homeostatic competition between phasic and tonic inhibition. 

    "The GABAA receptors are the major inhibitory receptors in the brain and are localized at both synaptic and extrasynaptic membranes. Synaptic GABAA receptors mediate phasic inhibition, whereas extrasynaptic GABAA receptors mediate tonic inhibition. ... We propose a working model that both synaptic and extrasynaptic GABAA receptors may compete for limited receptor slots on the plasma membrane to maintain a homeostatic range of the total inhibition."   
    See:  GABA Gate  for full Abstract, Related citations, 1 Cited by and  Free PMC Article


2013    117<1207 
Distinct roles of synaptic and extrasynaptic GABAAreceptors in striatal inhibition dynamics.  

    "Striatonigral and striatopallidal projecting medium spiny neurons (MSNs) express dopamine D1 (D1+) and D2 receptors (D2+), respectively. Both classes receive extensive GABAergic input via expression of synaptic, perisynaptic, and extrasynaptic GABAA receptors."         
    See:  GABA Gate  for full Abstract, Related citations, 1 Cited by and  Free PMC Article  .  


2013   113<1207 
Dysfunctional astrocytic and synaptic regulation of hypothalamic glutamatergic transmission in a mouse model of early-life adversity: relevance to neurosteroids and programming of the stress response.   
    "Adverse early-life experiences, such as poor maternal care, program an abnormal stress response that may involve an altered balance between excitatory and inhibitory signals." 
    See:   Stress   for full Abstract, Related citations, Cited by's and   Free PMC Article 





References Worthy of Further Consideration:

2013    117<1207 
Distinct roles of synaptic and extrasynaptic GABAAreceptors in striatal inhibition dynamics.  

    "Striatonigral and striatopallidal projecting medium spiny neurons (MSNs) express dopamine D1 (D1+) and D2 receptors (D2+), respectively. Both classes receive extensive GABAergic input via expression of synaptic, perisynaptic, and extrasynaptic GABAA receptors."     

  

2013    160<1206 
Homeostatic competition between phasic and tonic inhibition. 

    "The GABAA receptors are the major inhibitory receptors in the brain and are localized at both synaptic and extrasynaptic membranes. Synaptic GABAA receptors mediate phasic inhibition, whereas extrasynaptic GABAA receptors mediate tonic inhibition.


2012      (from a different search)
Evolution of the basal ganglia: dual-output pathways conserved throughout vertebrate phylogeny.   
    "GABAergic SNr projection neurons are tonically active and project to the thalamus and brainstem motor areas." 



2011   280<1206 
Intrinsic and integrative properties of substantia nigra pars reticulata neurons.  

    "The GABA projection neurons of the substantia nigra pars reticulata (SNr) are output neurons for the basal ganglia and thus critical for movement control. 


2008
Diencephalic locomotor region in the lamprey--afferents and efferent control.

    "
These findings suggest that GABAergic projections provide tonic inhibition that once turned off can release locomotion."    


2008    460<1206 
Tonic GABAergic inhibition of sympathetic preganglionic neurons: a novel substrate for sympathetic control.   
    "The sympathetic tone is primarily defined by the level of activity of the sympathetic preganglionic neurons. We report a novel inhibitory influence on sympathetic activity, that of tonic GABAergic inhibition which could have a profound global effect on sympathetic outflow."    


2006    607<1206   
Tonic GABA(A) receptor-mediated currents in human brain 
    "GABA(A) receptors can mediate both phasic (synaptic) and tonic (extrasynaptic) forms of inhibition. It has been proposed that tonic inhibition plays a critical part in controlling neuronal and network excitability.



2006    632>1206 
GABAergic mechanisms in regulating the activity state of substantia nigra pars reticulata neurons   

    "Substantia nigra reticulata is the major output structure of the basal ganglia involved in somatosensory integration and organization of movement.
 


2005    84<349
Mechanisms for selection of basic motor programs--roles for the striatum and pallidum
.
     "The nervous system contains a toolbox of motor programs in the brainstem and spinal cord--that is, neuronal networks designed to handle the basic motor repertoire required for survival, including locomotion, posture, eye movements, breathing, chewing, swallowing and expression of emotions. The neural mechanisms responsible for selecting which motor program should be recruited at a given instant are the focus of this review. Motor programs are kept under tonic inhibition by GABAergic pallidal neurons (the output nuclei of the basal ganglia). The motor programs can be relieved from pallidal inhibition through activation of striatal neurons at the input stage of the basal ganglia. It is argued that the striatum has a prominent role in selecting which motor program should be called into action."  




1999    914<1206 
GABA(A) and GABA(B) antagonists differentially affect the firing pattern of substantia nigra dopaminergic neurons in vivo. 
    "These data demonstrate that dopaminergic neurons in vivo are under tonic GABAergic inhibition."  



1999    916<1206 
GABAergic control of rat substantia nigra dopaminergic neurons: role of globus pallidus and substantia nigra pars reticulata. 
   
    "... at least one important way in which local application of bicuculline induces burst firing of dopaminergic neurons is by disinhibition of this tonic inhibitory input."  



1994     
Rat substantia nigra pars reticulata neurones are tonically inhibited via GABAA, but not GABAB, receptors in vitro,

    "The source of this GABA tone is likely to be from recurrent axon collaterals of SNr neurones themselves."


1984 1210<1240
Synaptic organization of the basal ganglia: an electroanatomical approach in the rat.  

   "The findings reported clearly establish that SNr exerts a tonic inhibitory influence on its collicular and thalamic targets ... the striatum may achieve a complex-spatial pattern of facilitation in a large spectrum of structures related to ocular and cephalic motor activity by inhibiting the inhibitory nigrothalamic and nigrocollicular branched neurons."  


1981 1228<1240
Evidence for a tonic GABAergic control of serotonin neurons in the median raphe nucleus.

    "The results provide evidence of a tonic inhibition by GABA of 5-HT neuronal activity in the median raphe nucleus."  


1980 1234<1240  
Nucleus accumbens to globus pallidus GABA projection: electrophysiological and iontophoretic investigations.  

    "This is indicative of the removal of a tonic GABA input onto these neurons."    



SubC    Tonic Inhibition 
170601 - 1841   



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