Brain stimulation changes negative emotion perception

Processing of negative emotion can be strengthened or weakened by tuning the excitability of the right frontal part of the brain. Using magnetic stimulation outside the brain, a technique called repetitive transcranial magnetic stimulation (rTMS), researchers at University of Münster, Germany, show that, despite the use of inhibitory stimulation currently used to treat depression, excitatory stimulation  reduced a person's response to fearful images.

The study confirms that modulating the frontal region of the brain, in the right hemisphere, directly effects the regulation of processing of emotional information in the brain in a 'top-down' manner," said Cameron Carter, M.D., Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging , referring to the function of this region as a control center for the emotion-generating structures of the brain. "These results highlight and expand the scope of the potential therapeutic applications of rTMS," said Dr. Carter.

In depression, processing of emotion is disrupted in the frontal region of both the left and right brain hemispheres (known as the dorsolateral prefrontal cortices, dlPFC). The disruptions are thought to be at the root of increased negative emotion and diminished positive emotion in the disorder. Reducing excitability of the right dlPFC using inhibitory magnetic stimulation has been shown to have antidepressant effects, even though it's based on an idea that this might reduce processing of negative emotion in depression that has yet to be fully tested in humans.

Researchers divided healthy participants into two groups to compare the effects of a single-session of excitatory or inhibitory magnetic stimulation of the right dlPFC. They performed rTMS while the participants viewed images of fearful faces to evoke negative emotion, or neutral faces for a comparison. Excitatory and inhibitory rTMS had opposite effects-excitatory reduced visual sensory processing of fearful faces, whereas inhibitory increased visual sensory processing. Similarly, excitatory rTMS reduced participants' reaction times to respond to fearful faces and reduced feelings of emotional arousal to fearful faces, which were both increased by inhibitory rTMS.
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Brain zaps for Tourette syndrome

Electric zaps can rewire the brains of Tourette syndrome patients, effectively reducing their uncontrollable vocal and motor tics. The procedure, called deep brain stimulation (DBS), improved tic severity by nearly half in patients with uncontrolled Tourette symptoms.

According to Dr. Michael Okun, chair of neurology and co-director of the Movement Disorders Center at the University of Florida's College of Medicine, much improvement in these symptoms is difficult when using medication or behavioral therapy.

With DBS, brain surgeons run thin electric leads to specific regions of the basal ganglia, a cluster of nerves in the brain related to motor control and behavior, then apply electricity to the brain circuits they've most closely linked to Tourette, to try to control the patient's tics. then introduce electricity into the brain to change the way these circuits function.

However, the procedure still needs more work. More than a third of patients experienced adverse events, most often slurred speech or a pins-and-needles sensation. These side effects occur when electricity meant for one brain circuit unintentionally spreads to other nearby nerves but the adverse effects are reversible.

Tourette patients are typically treated using medications and speech or behavioral therapy. Another option for severe Tourette cases is deep brain stimulation, which also used to treat many other motor disorders, including Parkinson's disease, essential tremor and multiple sclerosis.

Researchers wanted a better idea of whether DBS is effective in treating severe cases of uncontrolled Tourette, which can cause motor tics so strong that people end up hurting themselves. The average tic severity patients that used DBS improved by 45 percent within one year of implant.
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Brain stimulation may help people suffering from schizophrenia

Brain stimulation therapies involve activating or inhibiting the brain directly with electricity. It could be used to treat cognitive deficits frequently associated with schizophrenia.

Schizophrenia is a chronic mental disorder characterised by abnormal social behavior. This can make it difficult for affected people to plan, focus, pay attention and remember information.

Problems in short-term memory and decision making, which are often severely impaired in people with schizophrenia can be corrected by brain stimulation.

Researchers used neuromodulation - transcranial direct current stimulation (tDCS) - to check if they could correct some of these cognitive deficit in people with schizophrenia.

The researchers applied tDCS with tasks which specifically tapped into 'working memory' and ' executive functioning ': the principle was that 'training' the brain in regions that are typically poorly performing in schizophrenia would be enhanced by the brain stimulation technique.

An improvement in cognitive performance was discovered in those who had tDCS brain stimulation after 24 hours. This shows that changes in the
brain cells induced by neuromodulation may take some time to occur.

The researchers also ran brain imaging analyses to determine what was happening in the brain as these changes occurred. They discovered that tDCS was linked with changes in brain activity in regions associated with working memory and cerebellum.
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