Serotonergic Modulation of Sensory Representation in a Central Multisensory Circuit Pathway Specific

Hello everyone,

I don't think this has been shared in the support forum yet but i found it very interesting since my tinnitus started from an SSRI called Lexapro/Cipralex 5mg.

Here's a short version of the study:


Highlights

• In a multisensory integrator, 5-HT readjusts the relative strength of different inputs
• 5-HT enhances excitability of principal cells and auditory input-driven interneurons
• Principal cells then respond well to multisensory input, yet have weaker auditory drive
• 5-HT therefore operates at the microcircuit level to modulate sensory processing

Summary

Many studies have explored how neuromodulators affect synaptic function, yet little is known about how they modify computations at the microcircuit level. In the dorsal cochlear nucleus (DCN), a region that integrates auditory and multisensory inputs from two distinct pathways, serotonin (5-HT) enhances excitability of principal cells, predicting a generalized reduction in sensory thresholds. Surprisingly, we found that when looked at from the circuit level, 5-HT enhances signaling only from the multisensory input, while decreasing input from auditory fibers. This effect is only partially explained by an action on auditory nerve terminals. Rather, 5-HT biases processing for one input pathway by simultaneously enhancing excitability in the principal cell and in a pathway-specific feed-forward inhibitory interneuron. Thus, by acting on multiple targets, 5-HT orchestrates a fundamental shift in representation of convergent auditory and multisensory pathways, enhancing the potency of non-auditory signals in a classical auditory pathway.


Graphical Abstract



Link to study is found here:
https://www.cell.com/cell-reports/fulltext/S2211-1247(17)31098-7



Another article said this:

Recently, Tang et al (2017) have provided some further insight into the role of serotonin on tinnitus and some additional support to not using SSRIs for tinnitus management. Using mice, Tang and colleagues examined changes induced by serotonin in the dorsal cochlear nucleus (DCN), the portion of the cochlear nucleus with inhibitory characteristics. Aberrant serotonin signaling has previously been implicated with hyperactivity in the DCN related to tinnitus. Tang identified that serotonin does not simply or globally increase activity in the DCN, but rather the neurotransmitter appears to suppress signaling through the auditory pathway while enhancing transmission through a multisensory pathway. This activation may have positive biological implications, such as integration of multisensory input for response to salient environmental events or negative implications, such as tinnitus and help explain modulation of tinnitus with head movement and changes in jaw position.

More information:
https://www.audiology.org/news/ssri-and-tinnitus

 

It seems like everytime I stop Anafranil, after a couple of days my tinnitus does get lower and I have much better days then I have without it. But then of course it is there to stop obsessive thoughts. So live with louder tinnitus or OCD.