Transcranial Direct Current Stimulation
Transcranial direct current stimulation has been gaining popularity in recent years as a noninvasive brain stimulation research method. Some studies have investigated its use as a potential treatment for various types of dysfunction, including depression, Parkinson’s Disease, and age-related declines in memory and spatial navigation, because of the maintenance of its inhibitory or facilitatory effects even after stimulation has ceased. Below are a few such studies and review articles about this method.
ABSTRACT:
Transcranial Direct Current Stimulation Modulates Activation and Effective Connectivity During Spatial Navigation (In Press)
Background: Allocentric navigation declines with age and neurologic disease whereas egocentric navigation does not; differences that likely arise from maladaptive changes in brain regions mediating spatial (parietal cortex; hippocampus) but not procedural processing (caudate nucleus). Transcranial direct current stimulation (tDCS) holds promise for treating such decline given its ability to modulate neuronal excitability, but its effects have yet to be examined on spatial navigation.
Objectives/hypotheses: Using healthy young adults as a model, Study 1 intended to validate a novel spatial navigation paradigm using functional magnetic resonance imaging (fMRI). Using these data to determine targets for tDCS, Study 2 aimed to determine if 1) stimulation modulates activation in a polarity-specific manner; 2) stimulation results in global and/or task-specific activation changes; 3) activation changes are accompanied by changes in effective connectivity.
Methods: All participants underwent fMRI while learning allocentric and egocentric environments. Twelve participants completed Study 1. In Study 2, 16 participants were randomized to 20 min of tDCS (2 mA) using a montage with the anode over PZ and cathode over AF4 (P+F−) or the reverse montage (P−F+).
Results: Study 1 revealed that distinct networks preferentially mediate allocentric and egocentric navigation. Study 2 revealed polarity-dependent changes in activation and connectivity. The P+F− montage increased these measures in spatial regions, especially during allocentric navigation, and the caudate nucleus. Conversely, the P−F+ montage increased activation and connectivity in lateral prefrontal cortices and posterior hippocampus.
Conclusions: These findings support the neuromodulatory effects of tDCS in non-motor areas and demonstrate proof-of-principle for ameliorating age- and disease-related decline in navigational abilities. [Hampstead, B.M., Brown, G. S., & Hartley, J. F. (In Press). Brain Stimulation.]
FURTHER READING:
ABSTRACT:
Transcranial Direct Current Stimulation Modulates Activation and Effective Connectivity During Spatial Navigation (In Press)
Background: Allocentric navigation declines with age and neurologic disease whereas egocentric navigation does not; differences that likely arise from maladaptive changes in brain regions mediating spatial (parietal cortex; hippocampus) but not procedural processing (caudate nucleus). Transcranial direct current stimulation (tDCS) holds promise for treating such decline given its ability to modulate neuronal excitability, but its effects have yet to be examined on spatial navigation.
Objectives/hypotheses: Using healthy young adults as a model, Study 1 intended to validate a novel spatial navigation paradigm using functional magnetic resonance imaging (fMRI). Using these data to determine targets for tDCS, Study 2 aimed to determine if 1) stimulation modulates activation in a polarity-specific manner; 2) stimulation results in global and/or task-specific activation changes; 3) activation changes are accompanied by changes in effective connectivity.
Methods: All participants underwent fMRI while learning allocentric and egocentric environments. Twelve participants completed Study 1. In Study 2, 16 participants were randomized to 20 min of tDCS (2 mA) using a montage with the anode over PZ and cathode over AF4 (P+F−) or the reverse montage (P−F+).
Results: Study 1 revealed that distinct networks preferentially mediate allocentric and egocentric navigation. Study 2 revealed polarity-dependent changes in activation and connectivity. The P+F− montage increased these measures in spatial regions, especially during allocentric navigation, and the caudate nucleus. Conversely, the P−F+ montage increased activation and connectivity in lateral prefrontal cortices and posterior hippocampus.
Conclusions: These findings support the neuromodulatory effects of tDCS in non-motor areas and demonstrate proof-of-principle for ameliorating age- and disease-related decline in navigational abilities. [Hampstead, B.M., Brown, G. S., & Hartley, J. F. (In Press). Brain Stimulation.]
FURTHER READING:
- Transcranial direct current stimulation—update 2011. [Nitsche & Paulus. (2011). Restorative Neurology and Neuroscience, 29(6): 463-492.]
- Noninvasive brain stimulation with transcranial magnetic or direct current stimulation (TMS/tDCS)—From insights into human memory to therapy of its dysfunction [Sparing & Mottaghy {2008). Methods, 44(4): 329-337.]
- Treatment of depression with transcranial direct current stimulation (tDCS): A review [Nitsche, et al. (2009). Experimental Neurology. 219(1): 14-19.]
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