Back to Search
Start Over
Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis
- Source :
- Experimental Brain Research
- Publication Year :
- 2015
- Publisher :
- Springer, New York, 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.
- Subjects :
- Adult
Male
medicine.medical_specialty
sLORETA
Short-term memory
Alpha (ethology)
Electroencephalography
Audiology
Words
Superior temporal gyrus
Young Adult
Fractal
medicine
Coherence (signal processing)
Humans
Theta Rhythm
Beta (finance)
Mathematics
Cerebral Cortex
Communication
ERSPs
medicine.diagnostic_test
business.industry
General Neuroscience
Task (computing)
Electroencephalogram
Fractals
Memory, Short-Term
Spectral power
Speech Perception
Female
business
Beta Rhythm
Fractal dimension
Coherence
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Experimental Brain Research
- Accession number :
- edsair.doi.dedup.....dd78d4cba7b2b999ae0e36e2f675312b