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

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

Research output: Contribution to journalArticle

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 normal-hearing 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
Issue number5
DOIs
Publication statusPublished - Jun 23 2018

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Auditory Cortex
Hearing
Noise
Noise-Induced Hearing Loss
Pyramidal Cells
Neuronal Plasticity
Spine
Dendritic Spines
Synaptophysin
Cochlea
Dendrites
Transcranial Direct Current Stimulation
Synaptic Transmission
Fluorescent Antibody Technique
Western Blotting
Staining and Labeling
Brain

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Anodal transcranial direct current stimulation affects auditory cortex plasticity in normal-hearing and noise-exposed rats. / Paciello, Fabiola; Podda, Maria Vittoria; Rolesi, Rolando; Cocco, Sara; Petrosini, Laura; Troiani, Diana; Fetoni, Anna Rita; Paludetti, Gaetano; Grassi, Claudio.

In: Brain Stimulation, Vol. 11, No. 5, 23.06.2018, p. 1008-1023.

Research output: Contribution to journalArticle

Paciello, Fabiola ; Podda, Maria Vittoria ; Rolesi, Rolando ; Cocco, Sara ; Petrosini, Laura ; Troiani, Diana ; Fetoni, Anna Rita ; Paludetti, Gaetano ; Grassi, Claudio. / Anodal transcranial direct current stimulation affects auditory cortex plasticity in normal-hearing and noise-exposed rats. In: Brain Stimulation. 2018 ; Vol. 11, No. 5. pp. 1008-1023.
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T1 - Anodal transcranial direct current stimulation affects auditory cortex plasticity in normal-hearing and noise-exposed rats

AU - Paciello, Fabiola

AU - Podda, Maria Vittoria

AU - Rolesi, Rolando

AU - Cocco, Sara

AU - Petrosini, Laura

AU - Troiani, Diana

AU - Fetoni, Anna Rita

AU - Paludetti, Gaetano

AU - Grassi, Claudio

N1 - Copyright © 2018 Elsevier Inc. All rights reserved.

PY - 2018/6/23

Y1 - 2018/6/23

N2 - 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 normal-hearing 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.

AB - 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 normal-hearing 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.

U2 - 10.1016/j.brs.2018.05.017

DO - 10.1016/j.brs.2018.05.017

M3 - Article

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VL - 11

SP - 1008

EP - 1023

JO - Brain Stimulation

JF - Brain Stimulation

SN - 1935-861X

IS - 5

ER -