Cross references: Rhombencephalon Medulla Oblongata Reticular Activating Sytem
See: Amphioxus Evolution . 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. 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 . 55<144 1999 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." 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 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. 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 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. |