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?
See: Reticulospinal Transmission for summary, Related citations and Cited by's.
Monosynaptic excitatory amino acid transmission from the posterior rhombencephalic reticular nucleus to spinal neurons involved in the control of locomotion in lamprey.
This is the first mention of the "posterior rhombencephalic reticular nucleus" .
See: Initiation of Locomotion in Lampreys .
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.
Visual potentiation of vestibular responses in lamprey reticulospinal neurons.
"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 ..." .
"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."
This is another example of behavior influenced by sensory input.
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.
"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."
See: Initiation of Locomotion in Lampreys for full Abstract, Related citations, Cited by's and Full Free Text.
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."
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.
See: Mesencephalic Locomotor Region for full Abstract, Related citations and Cited by's .
2. See: 23<144 2007 Respiratory rhythms generated in the lamprey rhombencephalon, above.