Anodal transcranial direct current stimulation affects auditory cortex plasticity in normal-hearing and noise-exposed rats

Fabiola Paciello, Maria Vittoria Podda, Anna Rita Fetoni, Gaetano Paludetti, Claudio Grassi, Rolando Rolesi, Sara Cocco, Diana Troiani, Laura Petrosini

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Background: Transcranial direct current stimulation (tDCS) is a non-invasive tool capable to modulate cortical functions by affecting neuronal excitability and synaptic plasticity. Objective: Here we investigated the effects of anodal tDCS on auditory cortex (ACx) in normal-hearing rats and following a paradigm of noise-induced hearing loss (NIHL), that causes morphological alterations in ACx pyramidal neurons. Methods: Male rats exposed to intense pure tone (10 kHz) were subsequently subjected to unilateral anodal tDCS of ACx and changes in dendritic morphology and spines were assessed by Golgi-Cox staining 30 days after the onset of the acoustic trauma. Molecular and functional changes were investigated by Western immunoblotting, immunofluorescence experiments and electrophysiological recordings in brain slices. Results: We found that NIHL altered dendritic morphology by decreasing spine density, mostly in layer 2/3 pyramidal neurons. Interestingly, tDCS increased ACx spine density, targeting apical dendrites of layer 2/3 and 5/6 pyramidal neurons in rats with normal auditory function and both apical and basal arborizations in layer 2/3 of NIHL rats. Twenty-four hours after tDCS, Bdnf and synaptophysin levels in ACx increased both in normal-hearing and noise-exposed rats. Field recordings showed that basal synaptic transmission at layer 2/3 horizontal connections was significantly reduced in noise-exposed rats compared to normal-hearing animals and, notably, input-output curves of noise-exposed animals subjected to tDCS were similar to those of normalhearing rats. Conclusions: Our findings provide novel evidence that anodal tDCS affects structural plasticity in the ACx suggesting that it might be beneficial in treating cortical alterations due to cochlear damage.
Original languageEnglish
Pages (from-to)1008-1023
Number of pages16
JournalBrain Stimulation
Volume11
DOIs
Publication statusPublished - 2018

Keywords

  • Auditory cortex
  • Brain-derived neurotrophic factor
  • Dendritic spines
  • Personalized medicine
  • Synaptic transmission
  • tDCS

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