Sensory Input

Cross references:  Locomotion Sequence   Locomotion Sequence Revision     
Sensory System     Ganglion   Basal Ganglia    Pseudounipolar Neuron    
Dorsal Root Ganglion     Spinal Cord   

Sensory receptor (Wiki)   
In a sensory system, a sensory receptor is a sensory nerve ending that responds to a stimulus in the internal or external environment of an organism. In response to stimuli, the sensory receptor initiates sensory transduction by creating graded potentials or action potentials in the same cell or in an adjacent one."  


Searching Google for "sensory ganglion" found 981,000 references: 
    See:  Ganglion 

Searching PubMed for "sensory ganglion" found 31,060 references:      

Searching PubMed for "sensory ganglion neurotransmitter" found 5,389 references:      

Searching PubMed for "sensory ganglion glutamate" found 803 references:   

Searching PubMed for "sensory ganglion glutamate ionotropic" found 53 references:   

Searching PubMed for "sensory ganglion glutamate metabotropic" found 83 references: 

    So what evidence do I have that the Rhombencephalon receives sensory input? 
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  
        lateral line,  
        cutaneous and  

inputs are localized in the rhombencephalic region of the lamprey brainstem
, unlike the 
        visual inputs that are relayed in the mesencephalic region.

Cell groups were labeled ipsilateral to the injection site
    in the thalamus (corpi geniculati; pars dorsalis thalami lateralis and medialis; nucleus (n.) subhabenularis lateralis),
    in the epithalamus (n. commissura posteriori) and
    in the pretectum.    
Cell groups were labeled bilaterally
    within the dorsal region along the diencephalic-mesencephalic border (caudal pretectum and rostral tectum opticum),
    in tectum opticum, torus semicircularis, and tegmentum mesencephali.  

For full Abstract and 143 Related citations,
    See:  Diencephaloreticular Transmission

Rhombencephalon  (The Hind-brain or Rhombencephalon. Gray, Henry. 1918 and Rhombencephalon Sensory Interneurons) .

I'm still working on   Diencephaloreticular Transmission .  "I'm going to have to look at this more carefully, but my initial impression is that the nuclei identified as afferent to the rhombencephalon (see above) are not the nuclei which receive the initial sensory input.     On the other hand, perhaps there are no nuclei which receive the initial sensory input.  Perhaps the initial sensory input goes straight to the interneurons. 

More evidence that Rhombencephalon receives sensory input  
    from: 143/144 Related citations
1998 Diencephalic and mesencephalic projections to rhombencephalic reticular nuclei in lampreys

    32<143 2005  
The trigeminal sensory relay to reticulospinal neurones in lampreys   
    "This study was carried out to identify lamprey neurones relaying trigeminal sensory inputs to reticulospinal cells. ... Altogether, these results suggest that cells located within the trigeminal descending tract and projecting to reticular nuclei are likely to be the sensory trigeminal relays to reticulospinal neurones in lampreys."    
My comment:   
    This makes it sound as though the "trigeminal sensory inputs" are afferent to "cells located within the trigeminal descending tract and projecting to reticular nuclei".  So, perhaps the trigeminal sensory inputs are to the relay neurons.    

    11<143  2008  
Afferent and efferent connections of the mesencephalic reticular formation in goldfish.   
    See:  Mesencephalic Locomotor Region  .  

I'm looking for possible sensory interneurons included in discrete nuclei.  See: 

    Sensory System (all from Wikipedia): 

The visual system includes the eyes, the connecting pathways through to the visual cortex and other parts of the brain. The illustration shows the mammalian system.

Human visual system - Components

Three part system hypothesis of visual perceptions

  • First system - movement, location and spatial organization
  • Second system - colour perception
  • Third system - perception of shapes

  • Gustatory system        
  •     "In humans, the sense of taste is conveyed via three of the twelve cranial nerves. The facial nerve (VII) carries taste sensations from the anterior two thirds of the tongue, the glossopharyngeal nerve (IX) carries taste sensations from the posterior one third of the tongue while a branch of the vagus nerve (X) carries some taste sensations from the back of the oral cavity.   
  •     Cranial nerve V or the trigeminal nerve provides information concerning the general texture of food as well as the taste-related sensations of peppery or hot."  


1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal Epithelium 5: Glomerulus 6: Olfactory receptor cells "

Axons from the olfactory sensory neurons converge in the olfactory bulb to form clusters called glomeruli (singular glomerulus). Inside the glomerulus, the axons contact the dendrites of mitral cells and several other types of cells. Mitral cells send their axons to a number of brain areas, including the anterior olfactory nucleus, piriform cortex, the medial amygdala, the entorhinal cortex, and the olfactory tubercle .[1]

Molecules of odorants passing through the superior nasal concha of the nasal passages dissolve in the mucus lining the superior portion of the cavity and are detected by olfactory receptors on the dendrites of the olfactory sensory neurons. ... The binding of the ligand (odor molecule or odorant) to the receptor leads to an action potential in the receptor neuron, via a second messenger pathway, "   

Early Olfactory System

    "The axons from the olfactory receptors converge in the outer layer of the olfactory bulb within small (~50 micrometers in diameter) structures called glomeruli. Mitral cells, located in the inner layer of the olfactory bulb, form synapses with the axons of the sensory neurons within glomeruli and send the information about the odor to other parts of the olfactory system, where multiple signals may be processed to form a synthesized olfactory perception. A large degree of convergence occurs, with twenty-five thousand axons synapsing on twenty-five or so mitral cells, and with each of these mitral cells projecting to multiple glomeruli. Mitral cells also project to periglomerular cells and granular cells that inhibit the mitral cells surrounding it (lateral inhibition). Granular cells also mediate inhibition and excitation of mitral cells through pathways from centrifugal fibers and the anterior olfactory nuclei.  

    The mitral cells leave the olfactory bulb in the lateral olfactory tract, which synapses on five major regions of the cerebrum: the anterior olfactory nucleus, the olfactory tubercle, the amygdala, the piriform cortex, and the entorhinal cortex. The anterior olfactory nucleus projects, via the anterior commissure, to the contralateral olfactory bulb, inhibiting it."   

    "In female humans, the sense of olfaction is strongest around the time of ovulation, significantly stronger than during other phases of the menstrual cycle and stronger than the sense in males.[18]

The MHC genes (known as HLA in humans) are a group of genes present in many animals and important for the immune system; in general, offspring from parents with differing MHC genes have a stronger immune system. Fish, mice and female humans are able to smell some aspect of the MHC genes of potential sex partners and prefer partners with MHC genes different from their own.[19][20]

Humans can detect individuals that are blood-related kin (mothers/fathers and children but not husbands and wives) from olfaction.[21] Mothers can identify by body odor their biological children but not their stepchildren. Preadolescent children can olfactorily detect their full siblings but not half-siblings or step siblings and this might explain incest avoidance and the Westermarck effect.[22] Functional imaging shows that this olfactory kinship detection process involves the frontal-temporal junction, the insula, and the dorsomedial prefrontal cortex but not the primary or secondary olfactory cortices, or the related piriform cortex or orbitofrontal cortex.[23] "

Note:  There's no acknowledgement of pleasure as mediated by the nucleus accumbens septi.  

Solitary Tract  is made up of primary sensory fibers and descending fibers of the
        facial, glossopharyngeal and vagus nerves


External links
     Anatomy of the medulla    



In addition to external stimuli, I need to look at internal stimuli.    

I'm going to pick and choose among the remaining links.  Since I'm particularly interested in sensory nuclei, I looked at:  Solitary nucleusGustatory nucleus and  Vestibular nuclei.  However, after spending some time looking at them, I realized that they are not immediately relevant to locomotion.   

So which sensory nuclei are immediately relevant to locomotion?   

119<143 1989
Origins of the descending spinal projections in petromyzontid and myxinoid agnathans.   
    "The existence of reticulospinal and possible vestibulo-, trigemino-, and solitary spinal projections" 

32<143 2005
The trigeminal sensory relay to reticulospinal neurones in lampreys.   
    "This study was carried out to identify lamprey neurones relaying trigeminal sensory inputs to reticulospinal cells. ... The candidate relay cells projecting to the MRRN were mostly clustered at the caudal vestibular nerve level within the trigeminal descending tract, whereas the majority of those projecting to the PRRN were located more caudally. ... A possible relay function for these cells was tested with electrophysiological experiments. ... Altogether, these results suggest that cells located within the trigeminal descending tract and projecting to reticular nuclei are likely to be the sensory trigeminal relays to reticulospinal neurones in lampreys."