Browsing by Author "Malaga, Karlo"

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    Computational Modeling of Deep Brain Stimulation in the Globus Pallidus Internus
    (2012-08-27) Malaga, Karlo;
    Neuromodulation is the functional modification of neural structures through the use of electrical stimulation1. Clinical applications include deep brain stimulation (DBS) for the treatment of neurological movement disorders such as Parkinson’s disease and essential tremor. The general procedure involves placing small electrodes in regions of the brain exhibiting pathological activity and then stimulating those regions with continuous pulses of electricity. Treatment outcome is strongly dependent on the precise placement of the electrodes and subsequent adjustment of the stimulation settings to fine-tune the therapy. DBS is now being used for treating dystonic movement disorders, where sustained muscle contractions cause twisting and repetitive movements and/or abnormal postures. One target of DBS for dystonia is the posteroventral globus pallidus internus (GPi). Stimulation of the GPi has yielded promising results for people with dystonia; however, specific stimulation settings providing maximum GPi activation and having minimal side-effects have yet to be determined. Here we use computational models to show how altering parameters such as electrode configuration, DBS lead placement and orientation, and stimulation voltage affects GPi modulation and activation of the cortical spinal tract (CST), the side-effect pathway. In one model, the electrode configuration of the lead was varied. Another model had the DBS lead translated 1 mm medial, lateral, anterior, and posterior from its original position to make predictions of possible motor side-effects in a non-human primate animal model. Such models can provide a framework for neurosurgeons and neurologists to improve current steering techniques that will optimize treatment outcome.
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    Computational Modeling of Deep Brain Stimulation in the Globus Pallidus Internus
    (2012-04-18) Malaga, Karlo
    Deep brain stimulation (DBS) is a neural interface technology developed to improve the quality of life for people with movement disorders (e.g., Parkinson’s disease, dystonia, essential tremor). The general procedure involves placing small electrodes in regions of the brain exhibiting pathological activity and then stimulating those regions with continuous pulses of electricity. Treatment outcome is strongly dependent on the precise placement of the electrodes in the brain and subsequent adjustment of the stimulation settings to fine-tune the therapy. Stimulation of the globus pallidus internus (GPi) has yielded promising results for people with dystonia, a neurological movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. However, specific stimulation settings that provide maximum GPi modulation and have minimal side-effects have yet to be determined. Here we use computational models to show how altering the DBS lead electrode configuration affects GPi modulation and activation of the cortical spinal tract (CST) (i.e., the side-effect pathway). GPi DBS simulations yielded a combination of cell activation and inhibition. Activation was found to be greatest around the cathode of the DBS lead. Modulated cells were localized relative to the lead and the degree of modulation decreased farther away. These results can provide a framework for neurosurgeons and neurologists to improve current techniques that will optimize treatment outcome.