scholarly journals Considerations on tinnitus retraining therapy and transcranial magnetic stimulation

2021 ◽  
Vol 29 ◽  
pp. 1-22
Author(s):  
Fernanda Santos Fernandes ◽  
Carlos Eduardo Batista de Sousa
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Acoustic Stimulus ◽  
Economic Life ◽  
Subjective Perception ◽  
Neural Pathways ◽  
Tinnitus Retraining Therapy ◽  
The Social ◽  
Retraining Therapy ◽  
Negative Feelings

Introduction. Tinnitus is a subjective perception of sound in the absence of an external acoustic stimulus. It has negative behavioral feelings associated, e.g., depression, insomnia, difficulty of concentration, anxiety, irritability, and panic. The feelings impact negatively on the social and economic life of individuals. Empirical data suggest that disorders in the auditory cortex and its neural pathways give rise to abnormal spontaneous activations associated with tinnitus. Understanding the causes remains challenging. However, the current hypothesis suggests that clusters of neural networks and subnetworks are involved in tinnitus generation. Central dynamic neuroplasticity induced by a peripheral loss of auditory input can cause tinnitus noise. To date, there is no widespread consensus about the most effective therapy for treating tinnitus. Objective. To reflect on two tinnitus therapies: Tinnitus Retraining Therapy (TRT) and Transcranial Magnetic Stimulation (TMS). Method. A narrative review. Explicit and systematic criteria were not adopted in searching for the theoretical framework. Results. TMS is promising compared to TRT because TMS acts on tinnitus neural mechanisms. TRT is effective on a behavioral level since it relieves mild and moderate tinnitus' negative feelings. Conclusion. TRT does not advance on the neural source, but only on the tinnitus perception. TMS acts directly on the neural causes. Both therapies have limitations and can work for some patients. However, the effect of TMS seems more efficient, although transient.

scholarly journals Can processing of face trustworthiness bypass early visual cortex? A transcranial magnetic stimulation masking study

2019 ◽  
Author(s):  
Shanice E. W. Janssens ◽  
Alexander T. Sack ◽  
Sarah Jessen ◽  
Tom A. de Graaf
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Stimulus Onset ◽  
Forced Choice ◽  
Conscious Perception ◽  
Neural Pathways ◽  
Social Species ◽  
Early Visual Cortex ◽  
Human Faces

AbstractAs a highly social species, we constantly evaluate human faces to decide whether we can trust someone. Previous studies suggest that face trustworthiness can be processed unconsciously, but the underlying neural pathways remain unclear. Specifically, the question remains whether processing of face trustworthiness relies on early visual cortex (EVC), required for conscious perception. If processing of trustworthiness can bypass EVC, then disrupting EVC should impair conscious trustworthiness perception while leaving forced-choice trustworthiness judgment intact. We applied double-pulse transcranial magnetic stimulation (TMS) to right EVC, at different stimulus onset asynchronies (SOAs) from presentation of a face in either the left or right hemifield. Faces were slightly rotated clockwise or counterclockwise, and were either trustworthy or untrustworthy. On each trial, participants discriminated 1) trustworthiness, 2) stimulus rotation, and 3) subjective visibility of trustworthiness. At early SOAs and specifically in the left hemifield, orientation processing (captured by the rotation task) was impaired by TMS. Crucially, though TMS also impaired subjective visibility of trustworthiness, no effects on trustworthiness discrimination were obtained. Conscious perception of face trustworthiness (captured by visibility ratings) relies on intact EVC, while forced-choice trustworthiness judgments may not. These results are consistent with the hypothesis that trustworthiness processing can bypass EVC. For basic visual features, extrastriate pathways are well-established; but face trustworthiness depends on a complex configuration of features. Its processing without EVC and outside of awareness is therefore of particular interest, further highlighting its ecological relevance.

Startle reveals independent preparation and initiation of triphasic EMG burst components in targeted ballistic movements

2013 ◽  
Vol 110 (9) ◽  
pp. 2129-2139 ◽  
Author(s):  
Christopher J. Forgaard ◽  
Dana Maslovat ◽  
Anthony N. Carlsen ◽  
Romeo Chua ◽  
Ian M. Franks
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Acoustic Stimulus ◽  
Elbow Extension ◽  
Movement Onset ◽  
Startling Acoustic Stimulus ◽  
Agonist And Antagonist ◽  
Triphasic Pattern ◽  
Ballistic Movements ◽  
Close Temporal Proximity

Muscles involved in rapid, targeted movements about a single joint often display a triphasic [agonist (AG1)-antagonist (ANT)-agonist (AG2)] electromyographic (EMG) pattern. Early work using movement perturbations suggested that for short movements, the entire EMG pattern was prepared and initiated in advance (Wadman WJ, Dernier van der Gon JJ, Geuze RH, Mol CR. J Hum Mov Stud 5: 3–17, 1979), whereas more recent transcranial magnetic stimulation evidence indicates that the ANT may be programmed separately (MacKinnon CD, Rothwell JC. J Physiol 528: 633–645, 2000) with execution of the bursts occurring serially (Irlbacher K, Voss M, Meyer BU, Rothwell JC. J Physiol 574: 917–928, 2006). The purpose of the current study was to investigate the generation of triphasic EMG bursts for movements of different amplitudes. In experiment 1, participants performed rapid elbow extension movements to 20° and 60° targets, and on some trials, a startling acoustic stimulus (SAS), which is thought to trigger prepared motor commands at short latency, was delivered at the onset of AG1. For short movements, this perturbation elicited ANT and AG2 early, suggesting the agonist and antagonist bursts may have been programmed independently. In contrast, the same manipulation did not disrupt EMG timing parameters for the long movements, raising the possibility that ANT and AG2 were not fully programmed in advance of movement onset. In experiment 2, an SAS was delivered later in the movement, which produced early onset of both ANT and AG2. We propose that the triphasic pattern is executed serially but believe the trigger signal for initiating the ANT burst occurs not in relation to the AG1 burst, but rather in close temporal proximity to the expected onset of ANT.

scholarly journals Chronic Ankle Instability and Neural Excitability of the Lower Extremity

2015 ◽  
Vol 50 (8) ◽  
pp. 847-853 ◽  
Author(s):  
Michelle M. McLeod ◽  
Phillip A. Gribble ◽  
Brian G. Pietrosimone
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Evoked Potentials ◽  
Magnetic Stimulation ◽  
Ankle Instability ◽  
Motor Evoked Potentials ◽  
Chronic Ankle Instability ◽  
Corticospinal Excitability ◽  
Vastus Medialis ◽  
Neural Pathways ◽  
Hoffmann Reflex

Context Neuromuscular dysfunction of the leg and thigh musculature, including decreased strength and postural control, is common in patients with chronic ankle instability (CAI). Understanding how CAI affects specific neural pathways may provide valuable information for targeted therapies. Objective To investigate differences in spinal reflexive and corticospinal excitability of the fibularis longus and vastus medialis between limbs in patients with unilateral CAI and between CAI patients and participants serving as healthy controls. Design Case-control study. Setting Research laboratory. Patients or Other Participants A total of 56 participants volunteered, and complete data for 21 CAI patients (9 men, 12 women; age = 20.81 ± 1.63 years, height = 171.57 ± 11.44 cm, mass = 68.84 ± 11.93 kg) and 24 healthy participants serving as controls (7 men, 17 women; age = 22.54 ± 2.92 years, height = 172.35 ± 10.85 cm, mass = 69.15 ± 12.30 kg) were included in the final analyses. Control participants were matched to CAI patients on sex, age, and limb dominance. We assigned “involved” limbs, which corresponded with the involved limbs of the CAI patients, to control participants. Main Outcome Measure(s) Spinal reflexive excitability was assessed via the Hoffmann reflex and normalized to a maximal muscle response. Corticospinal excitability was assessed using transcranial magnetic stimulation. Active motor threshold (AMT) was defined as the lowest transcranial magnetic stimulation intensity required to elicit motor-evoked potentials equal to or greater than 100 μV in 5 of 10 consecutive stimuli. We obtained motor-evoked potentials (MEPs) at percentages ranging from 100% to 140% of AMT. Results Fibularis longus MEP amplitudes were greater in control participants than in CAI patients bilaterally at 100% AMT (control involved limb: 0.023 ± 0.031; CAI involved limb: 0.014 ± 0.008; control uninvolved limb: 0.021 ± 0.022; CAI uninvolved limb: 0.015 ± 0.007; F1,41 = 4.551, P = .04) and 105% AMT (control involved limb: 0.029 ± 0.026; CAI involved limb: 0.021 ± 0.009; control uninvolved limb: 0.034 ± 0.037; CAI uninvolved limb: 0.023 ± 0.013; F1,35 = 4.782, P = .04). We observed no differences in fibularis longus MEP amplitudes greater than 110% AMT and no differences in vastus medialis corticospinal excitability (P > .05). We noted no differences in the Hoffmann reflex between groups for the vastus medialis (F1,37 = 0.103, P = .75) or the fibularis longus (F1,41 = 1.139, P = .29). Conclusions Fibularis longus corticospinal excitability was greater in control participants than in CAI patients.

scholarly journals High-intensity transcranial magnetic stimulation reveals differential cortical contributions to prepared responses

2019 ◽  
Vol 121 (5) ◽  
pp. 1809-1821 ◽  
Author(s):  
Victoria Smith ◽  
Dana Maslovat ◽  
Neil M. Drummond ◽  
Joëlle Hajj ◽  
Alexandra Leguerrier ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
High Intensity ◽  
Magnetic Stimulation ◽  
Acoustic Stimulus ◽  
Silent Period ◽  
Voluntary Movements ◽  
Wrist Flexion ◽  
Primary Driver ◽  
Startling Acoustic Stimulus ◽  
Movement Type

Corticospinal output pathways have typically been considered to be the primary driver for voluntary movements of the hand/forearm; however, more recently, reticulospinal drive has also been implicated in the production of these movements. Although both pathways may play a role, the reticulospinal tract is thought to have stronger connections to flexor muscles than to extensors. Similarly, movements involuntarily triggered via a startling acoustic stimulus (SAS) are believed to receive greater reticular input than voluntary movements. To investigate a differential role of reticulospinal drive depending on movement type or acoustic stimulus, corticospinal drive was transiently interrupted using high-intensity transcranial magnetic stimulation (TMS) applied during the reaction time (RT) interval. This TMS-induced suppression of cortical drive leads to RT delays that can be used to assess cortical contributions to movement. Participants completed targeted flexion and extension movements of the wrist in a simple RT paradigm in response to a control auditory go signal or SAS. Occasionally, suprathreshold TMS was applied over the motor cortical representation for the prime mover. Results revealed that TMS significantly increased RT in all conditions. There was a significantly longer TMS-induced RT delay seen in extension movements than in flexion movements and a greater RT delay in movements initiated in response to control stimuli compared with SAS. These results suggest that the contribution of reticulospinal drive is larger for wrist flexion than for extension. Similarly, movements triggered involuntarily by an SAS appear to involve greater reticulospinal drive, and relatively less corticospinal drive, than those that are voluntarily initiated.NEW & NOTEWORTHY Through the use of the transcranial magnetic stimulation-induced silent period, we provide novel evidence for a greater contribution of reticulospinal drive, and a relative decrease in corticospinal drive, to movements involuntarily triggered by a startle compared with voluntary movements. These results also provide support for the notion that both cortical and reticular structures are involved in the neural pathway underlying startle-triggered movements. Furthermore, our results indicate greater reticulospinal contribution to wrist flexion than extension movements.

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