Frontal midline theta connectivity is related to efficiency of WM maintenance and is affected by aging.
Representations in working memory (WM) are temporary, but can be refreshed for longer periods of time through maintenance mechanisms, thereby establishing their availability for subsequent memory tests. Frontal brain regions supporting WM maintenance operations undergo anatomical and functional changes with advancing age, leading to age related decline of memory functions. The present study focused on age-related functional connectivity changes of the frontal midline (FM) cortex in the theta band (4-8 Hz), related to WM maintenance. In the visual delayed-match-to-sample WM task young (18-26 years, N=20) and elderly (60-71 years N=16) adults had to memorize sample stimuli consisting of 3 or 5 items while 33 channel EEG recording was performed. The phase lag index was used to quantify connectivity strength between cortical regions. The low and high memory demanding WM maintenance periods were classified based on whether they were successfully maintained (remembered) or unsuccessfully maintained (unrecognized later). In the elderly reduced connectivity strength of FM brain region and decreased performance were observed. The connectivity strength between FM and posterior sensory cortices was shown to be sensitive to both increased memory demands and memory performance regardless of age. The coupling of frontal regions (midline and lateral) and FM-temporal cortices characterized successfully maintained trials and declined with advancing age. The findings provide evidence that a FM neural circuit of theta oscillations that serves a possible basis of active maintenance process is especially vulnerable to aging.
Institute of Cognitive Neuroscience and Psychology, RCNS, HAS, Hungary; Department of Cognitive Science, Institute of Psychology, Eötvös Loránd University, Budapest, Hungary. Electronic address: brigitta.toth@ttk.mta.hu.
Brigitta
B
Tóth
Institute of Cognitive Neuroscience and Psychology, RCNS, HAS, Hungary; Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary.
Zsófia
Z
Kardos
Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary.
Bálint
B
File
Institute of Cognitive Neuroscience and Psychology, RCNS, HAS, Hungary.
Roland
R
Boha
Department of Clinical Neurophysiology, VU University Medical Centre, Neuroscience Campus Amsterdam, Netherlands.
Cornelis Jan
CJ
Stam
Institute of Cognitive Neuroscience and Psychology, RCNS, HAS, Hungary; Department of Personality and Health Psychology, Institute of Psychology, Eötvös Loránd University, Budapest, Hungary.
Márk
M
Molnár
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D013826:Theta Rhythm / Q000502:physiology*; D055815:Young Adult
Aging; Frontal midline theta; Functional connectivity; Phase lag index; Working memory