Tinnitus is characterized by the subjective perception of sound in the ears or in the brain
without external stimulus. In about 30-50% of patients, tinnitus co-occurs with hyperacusis,
which is abnormal sensitivity to sounds even at low levels. Chronic tinnitus and hyperacusis
can be devastating since a significant proportion of sufferers develop sleep disturbances,
psychiatric conditions, and a small fraction commit suicide. Tinnitus is often accompanied by
difficulty concentrating and impairment on tasks that require sustained attention and
executive control. Currently there is no satisfactory treatment for tinnitus and hyperacusis,
contributing to patients' distress. Thus, there is an urgent need for interventions that
would suppress the symptoms and possibly cure the disorder. Although, the pathophysiology of
tinnitus and hyperacusis is not well understood, neurobiological research suggests that
tinnitus and hyperacusis can be attributed to maladaptive neuroplasticity triggered by damage
in the auditory system. Most symptoms of tinnitus have been attributed to the hyperactivity
and reorganization in the auditory cortex (AC) and dorsolateral prefrontal brain regions
(DLPFC). This suggests that electrical stimulation to the abnormally activated regions might
modulate these overactive regions and reduce tinnitus and hyperacusis. TDCS is a noninvasive
neurostimulation technique that uses weak electric currents (1-2 mA) applied to the scalp to
modulate brain responsiveness by temporarily altering neuronal resting membrane potentials.
It is proposed that this approach has a potential therapeutic value in treating tinnitus and
hyperacusis.
Our proposed project examines whether application of tDCS to AC and DLPFC combined with
active listening therapy serves to promote adaptive neuroplasticity and reduce subjective
perception of sound and emotional distress.
The Aims are to: (1) Determine whether tDCS can lead to significant improvement in tinnitus
and hyperacusis symptoms pre- versus post-stimulation and
(2) Examine electrophysiological responses and functional connectivity in the
fronto-temporal-parietal network of brain regions in response to tDCS vs. sham.
The expected outcomes from this research will provide evidence to support the design and
implementation of individualized tDCS protocols to potentiate treatment protocols that
address the core deficits in tinnitus and hyperacusis. Our data will contribute to a more
detailed understanding of the neurobiology of tinnitus and the mechanisms that contribute to
the subjective, emotional and cognitive symptoms. The results of our study have a potential
to develop effective treatment for the rehabilitation of tinnitus and contribute to the
clinical practice.
Summary of study sequence and procedures:
Week 1: Baseline screening, hearing assessment, tinnitus assessment (2 hours), one magnetic
resonance imaging (MRI) scan (45minutes), one electrophysiology recording (EEG-ERP)( 1 hour)
Weeks 2-4: tDCS with active listening therapy Part 1
- 2 weeks of 1-hour sessions using non-invasive brain stimulation paired with active
listening therapy
Weeks 5 and 6: rest-period, post-treatment assessment, one MRI scan (45 min), one EEG-ERP
session (1hour)
Weeks 7 to 9: tDCS with active listening therapy Part 2 (1 hour each sessions)
- 2 weeks of 1-hour sessions using non-invasive brain stimulation paired with active
listening therapy
Weeks 10 and 12: rest period and post-treatment assessment one MRI scan (45 min), one EEG-ERP
session (1hour)
Week 18: 2-month follow-up, tinnitus assessment, one MRI scan (45 min), one EEG-ERP session
(1 hour)
