Lamprey Rhombencephalon

Cross references:    Rhombencephalon     Medulla Oblongata     Reticular Activating Sytem  
Reticulospinal Transmission      Diencephaloreticular Transmission   
 
Locomotion Sequence Revision    Sensory Input    
Dictionary    Motor Programs      Perinatal Behavior    
 


Searching PubMed for "Lamprey Rhombencephalon" found 144 references: 
http://www.ncbi.nlm.nih.gov/pubmed/?term=lamprey+rhombencephalon   

Note: I've completed an initial survey of the references below .   My most interesting impression is that hunger-feeding and possibly also respiration are below the reticular formation on the neuroaxis.  Does this mean that they are more ancient?   
 


128<144    1982 
Brain neurons which project to the spinal cord in young larvae of the zebrafish   
http://www.ncbi.nlm.nih.gov/pubmed/7076887   
    See:  Reticulospinal Transmission for summary, Related citations and Cited by's.


123<144    1984 
Early development of descending pathways from the brain stem to the spinal cord in Xenopus laevis   
http://www.ncbi.nlm.nih.gov/pubmed/6335361   
    "
The observations demonstrate that already very early in development reticulospinal fibers and, somewhat later, Mauthner cell axons and vestibulospinal fibers innervate the spinal cord."    


102<144   1989
Origins of the descending spinal projections in petromyzontid and myxinoid agnathans. 

101<144  1989
Further evidence for excitatory amino acid transmission in lamprey reticulospinal neurons: selective retrograde labeling with (3H)D-aspartate.   

    See:   Lamprey Neurotransmitters 


99<144  
1989 
Monosynaptic excitatory amino acid transmission from the posterior rhombencephalic reticular nucleus to spinal neurons involved in the control of locomotion in lamprey.  
    See:  Reticulospinal Transmission  for full Abstract, Related citations and Cited by's.   
    My comment
This is the first mention of the "posterior rhombencephalic reticular nucleus" . 


77<144   
1996
The brains of lampreys and hagfishes: characteristics, characters, and comparisons.  

My comment
    The spinal cord > reticular formation > spinal cord loop may be an example of initiation of behavior by the rhombencephalon.     
    See:  Agnatha


75<144    1996 
A mesencephalic relay for visual inputs to reticulospinal neurones in lampreys.   
My comment
    This is an example of behavior which was initiated not by the Substantia Nigra pars Compacta  (SNc) and not by the rhombocephalon but by sensory input.  This may turn out to be what is actually happening in most cases.   


72<144    1996 
Visual potentiation of vestibular responses in lamprey reticulospinal neurons. 
http://www.ncbi.nlm.nih.gov/pubmed/8950094   
    "
The lamprey normally swims with the dorsal side up. Illumination of one eye shifts the set-point of the vestibular roll control system, however, so that the animal swims with a roll tilt towards the source of light (the dorsal light response). A tilted orientation is often maintained for up to 1 min after the stimulation. In present study, the basis for this behaviour was investigated at the neuronal level.  
    The middle rhombencephalic reticular nucleus (MRRN) is considered a main nucleus for the control of roll orientation in lampreys. Practically all MRRN neurons receive vestibular and visual input and project to the spinal cord. Earlier extracellular experiments had shown that optic nerve stimulation potentiates the response to vestibular stimulation in the ipsilateral MRRN. This most likely represents a neural correlate of the dorsal light response. Experiments were carried out in vitro on the isolated brainstem of the silver lamprey (Ichthyomyzon unicuspis). MRRN cells were recorded intracellularly, and the overall activity of descending systems was monitored with bilateral extracellular electrodes. The responses to 10 Hz optic nerve stimulation and 1 Hz vestibular nerve stimulation, and the influence of optic nerve stimulation on the vestibular responses, were investigated.  
     In most preparations, optic nerve stimulation excited practically all ipsilateral MRRN cells. After stimulation, the cell was typically depolarized and showed an increased level of synaptic noise for up to 80 s. In contralateral MRRN neurons, optic nerve stimulation usually evoked hyperpolarization or no response.  
    Vestibular nerve stimulation evoked compound excitatory postsynaptic potentials (EPSPs) or spikes in approximately 90% of the cells, both ipsilaterally and contralaterally. A smaller subpopulation of MRRN cells (approximately 10%) received vestibular inhibition. In 26 of 48 recorded MRRN cells, the response to vestibular stimulation was potentiated after ipsilateral optic nerve stimulation ..." .    
Important points
    "
Practically all MRRN neurons receive vestibular and visual input and project to the spinal cord."       
    "
In most preparations, optic nerve stimulation excited practically all ipsilateral MRRN cells."   
    "
Vestibular nerve stimulation evoked compound excitatory postsynaptic potentials (EPSPs) or spikes in approximately 90% of the cells, both ipsilaterally and contralaterally."  
My comment
    This is another example of behavior influenced by sensory input. 


65<144  
1997   
Diencephalic projection to reticulospinal neurons involved in the initiation of locomotion in adult lampreys Lampetra fluviatilis.    
    My comment
Thal > SLG 


63<144   
1998
Differential effects of the reticulospinal system on locomotion in lamprey. 

    See:  Lamprey Locomotion  .   


61<144  
1998
Diencephalic and mesencephalic projections to rhombencephalic reticular nuclei in lampreys.
  

    "Behavioral studies in lampreys of the northern genera, Ichthyomyzon, reveal that sensory inputs initiate and modulate locomotion by activation of reticulospinal (RS) neurones. 
    "The interneurones relaying afferent vestibular, trigeminal, lateral line, cutaneous and proprioceptive inputs are localized in the rhombencephalic region" 
    My comment:       
This is another example of behavior which was initiated, not by the Substantia Nigra pars Compacta  (SNc)  but by sensory input relayed by interneurones in the rhombencephalon.  This may turn out to be what is actually happening in most cases.   


60<144    1998 
Electrophysiological and neuropharmacological study of tectoreticular pathways in lampreys.  
http://www.ncbi.nlm.nih.gov/pubmed/9757053       
    "
The TR inputs were transmitted to reticular cells through monosynaptic and polysynaptic contacts. The synaptic transmission involved excitatory amino acids, acting through AMPA and NMDA receptors, while the inhibition was glycinergic."  


55<144    1999  
An anatomical study of brainstem projections to the trigeminal motor nucleus of lampreys
http://www.ncbi.nlm.nih.gov/pubmed/10336085   
    "
This study concentrates on the labeled neurons in the rhombencephalon, since the essential circuits for mastication and swallowing are confined to this region in higher vertebrates."  
    My comment
Perhaps the anatomy for feeding is even more ancient than the anatomy for locomotion.   


45<144    2003 
Nicotinic activation of reticulospinal cells involved in the control of swimming in lampreys. 
http://www.ncbi.nlm.nih.gov/pubmed/12534977  
    See:  Initiation of Locomotion in Lampreys  for full Abstract, Related citations and Cited by's.  


40<144    2004       
Free PMC Article   
Organization of higher-order brain areas that initiate locomotor activity in larval lamprey.   
http://www.ncbi.nlm.nih.gov/pubmed/15051142   
    "
These new results suggest that neurons in the RLR project rostrally to locomotor areas in the DLM and VMD."  
    My comment
This postulates communication from lower to higher levels, which is opposite of my basic assumption. 
    See:  Initiation of Locomotion in Lampreys  for full Abstract, Related citations and Cited by's.  


35<144    2005 

Evolution of the brain developmental plan: Insights from agnathans. 
http://www.ncbi.nlm.nih.gov/pubmed/15882571  
    See:  Amphioxus Evolution


27<144    2007 
Movements and muscle activity initiated by brain locomotor areas in semi-intact preparations from larval lamprey. 
http://www.ncbi.nlm.nih.gov/pubmed/17314244  
    See:  Initiation of Locomotion in Lampreys  for full Abstract, Related citations, Cited by's and Full Free Text. 


   26<144   2007    
Free PMC Article 
Muscarinic receptor activation elicits sustained, recurring depolarizations in reticulospinal neurons.  

    "
We propose that unilateral mAchR activation on specific cells in the caudal rhombencephalon activates a circuit that generates synchronous sustained, recurring depolarizations in bilateral populations of RS neurons."  


23<144    2007 
Respiratory rhythms generated in the lamprey rhombencephalon.  
http://www.ncbi.nlm.nih.gov/pubmed/17618060  
    "
Our results support the hypothesis that normal breathing depends on the activity of neurons located in the rostral rhombencephalon in lampreys, whereas the caudal rhombencephalon generates the slow pattern."  
    See also:  3<144  2013  Neuronal mechanisms of respiratory pattern generation are evolutionary conserved. 


22<144    2008 

Initiation of Locomotion in Lampreys  

http://www.ncbi.nlm.nih.gov/pubmed/17916380    
    See:  Initiation of Locomotion in Lampreys  for full Abstract, Related citations, Cited by's and notes. 


14<144    2011 
 
Localization, pharmacology, and organization of brain locomotor areas in larval lamprey.
http://www.ncbi.nlm.nih.gov/pubmed/21081157    Free PMC Article   
 
 
    See:  Initiation of Locomotion in Lampreys  for full Abstract and Related citations


5<144   
2013 
The multifunctional mesencephalic locomotor region. 
http://www.ncbi.nlm.nih.gov/pubmed/23360276   
    See:  Mesencephalic Locomotor Region  for full Abstract, Related citations and Cited by's  . 

   
3<144    2013 
Neuronal mechanisms of respiratory pattern generation are evolutionary conserved. 
http://www.ncbi.nlm.nih.gov/pubmed/23699521  
    "
A brainstem region, the paratrigeminal respiratory group (pTRG), has been suggested to play a crucial role in the respiratory rhythm generation in lampreys. ... pTRG neurons projecting to the vagal motoneuronal pool were identified in a restricted area of the rostral rhombencephalon at the level of the isthmic Müller cell I1 close to sulcus limitans of His."  
    My comments
1.  What is the "vagal motoneuronal pool" and where is it located?  This may be more fundamental to behavior than the previously identified reticular neurons.  
2.  See: 23<144  2007  Respiratory rhythms generated in the lamprey rhombencephalon, above. 










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