Abstract
The n-back task is widely used to investigate the neural basis of Working Memory (WM) processes. The principal aim of this study was to explore and compare the EEG power spectra during two n-back tests with different levels of difficulty (1-back vs. 3-back). Fourteen healthy subjects were enrolled (seven men and seven women, mean age 31.21 ± 7.05 years, range: 23–48). EEG was recorded while performing the N-back test, by means of 19 surface electrodes referred to joint mastoids. EEG analysis were conducted by means of the standardized Low Resolution brain Electric Tomography (sLORETA) software. The statistical comparison between EEG power spectra in the two conditions was performed using paired t-statistics on the coherence values after Fisher's z transformation available in the LORETA program package. The frequency bands considered were: delta (0.5–4 Hz); theta (4.5–7.5 Hz); alpha (8–12.5 Hz); beta (13–30 Hz); gamma (30.5–100 Hz). Significant changes occurred in the delta band: in the 3-back condition an increased delta power was localized in a brain region corresponding to the Brodmann Area (BA) 28 in the left posterior entorhinal cortex (T = 3.112; p < 0.05) and in the BA 35 in the left perirhinal cortex in the parahippocampal gyrus (T = 2.876; p < 0.05). No significant differences were observed in the right hemisphere and in the alpha, theta, beta, and gamma frequency bands. Our results indicate that the most prominent modification induced by the increased complexity of the task occur in the mesial left temporal lobe structures.
Highlights
Over the last 30 years the concept of working memory (WM) has been investigated extensively, from cognitive psychology to neuroscience (Baddeley, 2010, 2011)
Significant changes occurred in the delta band: in the 3-back condition an increased delta power was localized in a brain region corresponding to the Brodmann Area (BA) 28 in the left posterior entorhinal cortex (T = 3.112; p < 0.05) and in the BA 35 in the left perirhinal cortex in the parahippocampal gyrus (T = 2.876; p < 0.05)
The mean reaction time (RT) shows a significant increase in the 3-back condition [F(1.13) = 6.837; p = 0.021]
Summary
Over the last 30 years the concept of working memory (WM) has been investigated extensively, from cognitive psychology to neuroscience (Baddeley, 2010, 2011). On the basis of neuroimaging and functional studies, a multicomponent WM model has been proposed (Baddeley, 2000) According to this model, a “phonological loop” and a “visuo-spatial sketchpad” constitute a slave systems that can independently process different types of information. Muller e Knight (Muller and Knight, 2006) have proposed that the central executive is distributed along ventral and dorsal lateral prefrontal cortices It has been argued (Andres, 2003) that a more complex and dynamic view of its neural substrate is needed; for example, the central executive system does not include exclusively the frontal cortex, but it involves different brain areas, such as the Frontiers in Human Neuroscience www.frontiersin.org
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.
