We know that when muscles are not used they atrophy. Does something similar also happen in neurons if they do not receive any stimulus?


1 Answer 1


Short answer

Postsynaptic neuronal degeneration after deafferentation are notorious in the peripheral sensory systems. There, marked degenerative processes are present when input to the secondary neurons is lost due to degeneration of the primary sensory neurons. In other words

  • When the hair cells are lost in the cochlea, the auditory nerve degenerates (e.g., Kuyama, 2010);
  • When the retinal photoreceptors are lost, for example due to degenerative diseases like retinitis pigmentosa, bipolar and horizontal cells in the retina degenerate due to a loss of efferent input (Mazzoni et al., 2008). For more information see the works of Marc & Jones, e.g.., Jones & Marc (2005).

Note that in the central nervous system these effects play less of a role, as neurons have ample opportunity to reconnect to other neurons, for the better or worse; e.g., in the hearing impaired and visually impaired, spontaneous sensations of sound and visuals may develop and lead to tinnitus and photopsias, respectively. These symptoms are caused by cortical sensory neurons desperately and randomly looking for sensory input after being deafferented due to peripheral loss of hearing or vision. When they cannot obtain useful input any longer, they gather irrelevant, non-useful input and start generating spontaneous 'illusionary' perceptions instead.

- Jones & Marc, Exp Eye Res (2005); 81(2): 123-37
- Kuyama, J Neurosci (2009); 29(45): 14077–085)
- Mazzoni et al., J Neurosci (2008); 28(52): 14282–92

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    $\begingroup$ These examples are related to structural loss of contacts, with the retina case occurring in a background of general degeneration. Is the loss of B and H cells due to lack of input or simply the surrounding inflammatory environment? IMO, the OP is asking about loss of inputs or absent activity in otherwise healthy neurons with contacts intact, which is a subtly different question, no? In a non-diseased context, do neurons actually die if they don't fire for a while? Consider long term memories stored in synapses which may not be activated for many years. just my 2 cents.. $\endgroup$ Commented Nov 16, 2017 at 23:47
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    $\begingroup$ @LouisLeung there are no inflammatory responses afaik in the cochlea in the case of age related hearing loss and other forms of sensorineural HL so your comment doesn't apply there. In the retina I would have to double check. $\endgroup$
    – AliceD
    Commented Nov 17, 2017 at 5:50

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