Abstract
Neuronal oscillations in the theta and gamma bands have been shown to be important for cognition. Here we examined the temporal and spatial relationship between the two frequency bands in emotional processing using magnetoencephalography and an advanced dynamic beamformer source imaging method called synthetic aperture magnetometry. We found that areas including the amygdala, visual and frontal cortex showed significant event-related synchronization in both bands, suggesting a functional association of neuronal oscillations in the same areas in the two bands. However, while the temporal profile in both bands was similar in the amygdala, the peak in gamma band power was much earlier within both visual and frontal areas. Our results do not support a traditional view that the localizations of lower and higher frequencies are spatially distinct. Instead, they suggest that in emotional processing, neuronal oscillations in the gamma and theta bands may reflect, at least in visual and frontal cortex either different but related functional processes or, perhaps more probably, different computational components of the same functional process.
Highlights
Neuronal activities of the brain are characterized by rhythmic oscillations with a wide range of frequencies
Some recent studies reveal that gamma and theta are not spatially distinct but can be both present in the brain regions implicated in a task but with different temporal dynamics (e.g., Belluscio et al, 2012)
We reported gamma band activity within the amygdala, visual cortex and inferior frontal gyrus (IFG)/insula in response to emotional stimuli (Luo et al, 2007)
Summary
Neuronal activities of the brain are characterized by rhythmic oscillations with a wide range of frequencies (from less than 0.05 Hz to more than 500 Hz; Buzsaki and Draguhn, 2004). Neuronal oscillations are suggested to provide temporal and spatial codes, and to act within communication networks to coordinate distinct neural processes into highly ordered cognitive functions (Singer, 1999; Varela et al, 2001; Fries, 2005). Some recent studies reveal that gamma and theta are not spatially distinct but can be both present in the brain regions implicated in a task but with different temporal dynamics (e.g., Belluscio et al, 2012). A recent study indicates the presence of both theta and gamma activity in the hippocampus during maze learning; the oscillators at the gamma and theta frequencies were interdependent, leading to the suggestion that cross phase coupling can integrate multiple layers of information to support multiple time-scale control of neuronal spikes within and across structures (Belluscio et al, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
