Abstract
We examine the relative timing of numerous brain regions involved in human decisions that are based on external criteria, learned information, personal preferences, or unconstrained internal considerations. Using magnetoencephalography (MEG) and advanced signal analysis techniques, we were able to non-invasively reconstruct oscillations of distributed neural networks in the high-gamma frequency band (60–150 Hz). The time course of the observed neural activity suggested that two-alternative forced choice tasks are processed in four overlapping stages: processing of sensory input, option evaluation, intention formation, and action execution. Visual areas are activated first, and show recurring activations throughout the entire decision process. The temporo-occipital junction and the intraparietal sulcus are active during evaluation of external values of the options, 250–500 ms after stimulus presentation. Simultaneously, personal preference is mediated by cortical midline structures. Subsequently, the posterior parietal and superior occipital cortices appear to encode intention, with different subregions being responsible for different types of choice. The cerebellum and inferior parietal cortex are recruited for internal generation of decisions and actions, when all options have the same value. Action execution was accompanied by activation peaks in the contralateral motor cortex. These results suggest that high-gamma oscillations as recorded by MEG allow a reliable reconstruction of decision processes with excellent spatiotemporal resolution.
Highlights
Choosing plays an important role in our daily life, since it reflects our current environment and internal state, but it determines our future situation
In an attempt to obtain a more integrated and dynamic picture of the neural processes underlying visuo-motor choosing tasks in humans, this study used MEG recordings of neural oscillations in the high-gamma frequency band and advanced signal analysis techniques to reconstruct the activity of the entire cortex with high resolution in both space and time
Previous studies have demonstrated the reliability of the applied signal analysis techniques (Dalal et al, 2008; Sekihara et al, 2005), and we will show that the location of brain activations found in this study are largely in accordance with previous functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) studies, which confirms the validity of our results
Summary
Choosing plays an important role in our daily life, since it reflects our current environment and internal state, but it determines our future situation. The most conspicuous feature of decision making that distinguishes it phenomenologically from reflexive behavior is the faculty of acting according to current sensory representations of external conditions, but according to internal self-related values and preferences (Montague et al, 2006; Sugrue et al, 2004). This internal value-system depends on complex neural mechanisms. Studies investigating the neural processes underlying internal movement selection reported that the supplementary motor
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