TY  - JOUR
AU  - Stokić, Miodrag
AU  - Milovanović, Dragan
AU  - Ljubisavljević, Milos R.
AU  - Nenadović, Vanja
AU  - Cukić, Milena
PY  - 2015
UR  - http://intor.torlakinstitut.com/handle/123456789/428
AB  - The objective of this preliminary study was to quantify changes in complexity of EEG using fractal dimension (FD) alongside linear methods of spectral power, event-related spectral perturbations, coherence, and source localization of EEG generators for theta (4-7 Hz), alpha (8-12 Hz), and beta (13-23 Hz) frequency bands due to a memory load effect in an auditory-verbal short-term memory (AVSTM) task for words. We examined 20 healthy individuals using the Sternberg's paradigm with increasing memory load (three, five, and seven words). The stimuli were four-letter words. Artifact-free 5-s EEG segments during retention period were analyzed. The most significant finding was the increase in FD with the increase in memory load in temporal regions T3 and T4, and in parietal region Pz, while decrease in FD with increase in memory load was registered in frontal midline region Fz. Results point to increase in frontal midline (Fz) theta spectral power, decrease in alpha spectral power in parietal region-Pz, and increase in beta spectral power in T3 and T4 region with increase in memory load. Decrease in theta coherence within right hemisphere due to memory load was obtained. Alpha coherence increased in posterior regions with anterior decrease. Beta coherence increased in fronto-temporal regions. Source localization delineated theta activity increase in frontal midline region, alpha decrease in superior parietal region, and beta increase in superior temporal gyrus with increase in memory load. In conclusion, FD as a nonlinear measure may serve as a sensitive index for quantifying dynamical changes in EEG signals during AVSTM tasks.
PB  - Springer, New York
T2  - Experimental Brain Research
T1  - Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis
EP  - 3038
IS  - 10
SP  - 3023
VL  - 233
DO  - 10.1007/s00221-015-4372-z
ER  - 

@article{
author = "Stokić, Miodrag and Milovanović, Dragan and Ljubisavljević, Milos R. and Nenadović, Vanja and Cukić, Milena",
year = "2015",
abstract = "The objective of this preliminary study was to quantify changes in complexity of EEG using fractal dimension (FD) alongside linear methods of spectral power, event-related spectral perturbations, coherence, and source localization of EEG generators for theta (4-7 Hz), alpha (8-12 Hz), and beta (13-23 Hz) frequency bands due to a memory load effect in an auditory-verbal short-term memory (AVSTM) task for words. We examined 20 healthy individuals using the Sternberg's paradigm with increasing memory load (three, five, and seven words). The stimuli were four-letter words. Artifact-free 5-s EEG segments during retention period were analyzed. The most significant finding was the increase in FD with the increase in memory load in temporal regions T3 and T4, and in parietal region Pz, while decrease in FD with increase in memory load was registered in frontal midline region Fz. Results point to increase in frontal midline (Fz) theta spectral power, decrease in alpha spectral power in parietal region-Pz, and increase in beta spectral power in T3 and T4 region with increase in memory load. Decrease in theta coherence within right hemisphere due to memory load was obtained. Alpha coherence increased in posterior regions with anterior decrease. Beta coherence increased in fronto-temporal regions. Source localization delineated theta activity increase in frontal midline region, alpha decrease in superior parietal region, and beta increase in superior temporal gyrus with increase in memory load. In conclusion, FD as a nonlinear measure may serve as a sensitive index for quantifying dynamical changes in EEG signals during AVSTM tasks.",
publisher = "Springer, New York",
journal = "Experimental Brain Research",
title = "Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis",
pages = "3038-3023",
number = "10",
volume = "233",
doi = "10.1007/s00221-015-4372-z"
}

Stokić, M., Milovanović, D., Ljubisavljević, M. R., Nenadović, V.,& Cukić, M.. (2015). Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis. in Experimental Brain Research
Springer, New York., 233(10), 3023-3038.
https://doi.org/10.1007/s00221-015-4372-z

Stokić M, Milovanović D, Ljubisavljević MR, Nenadović V, Cukić M. Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis. in Experimental Brain Research. 2015;233(10):3023-3038.
doi:10.1007/s00221-015-4372-z .

Stokić, Miodrag, Milovanović, Dragan, Ljubisavljević, Milos R., Nenadović, Vanja, Cukić, Milena, "Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis" in Experimental Brain Research, 233, no. 10 (2015):3023-3038,
https://doi.org/10.1007/s00221-015-4372-z . .