A frequency band analysis of two-year-olds’ memory processes

Abstract

Research on the functional meaning of EEG frequency bands during memory processing has only examined two developmental periods: infancy and from late childhood to adulthood. The purpose of this study was to examine changes in EEG power for three toddler EEG frequency bands (3–5 Hz, 6–9 Hz, 10–12 Hz) during a verbal recall task. To this end, we asked three questions: (a) Which frequency band(s) discriminate baseline from memory processing?; (b) Which frequency band(s) differentiate between memory encoding and retrieval processes?; (c) Which frequency band(s) distinguish toddlers with high and low verbal recall performance? Analysis of 2-year-olds’ (n = 79) power values revealed that all three frequency bands differentiated the retrieval and encoding phases from the baseline phase; however, the particular regions that exhibited this dissociation varied. Retrieval-related increases in 3–5 Hz (theta) power were widespread. Only the 3–5 Hz and 6–9 Hz bands distinguished encoding and retrieval processes; retrieval power values were higher than encoding power values. High and low verbal recall performers were discriminated by all frequency bands; high performers had greater power values than low performers. Thus, the 3–5 Hz (theta) and 6–9 Hz (alpha) bands were most informative about 2-year-olds’ memory processes. Theta and alpha rhythms are critical to memory processes during late childhood and adulthood, and our findings provide initial evidence that these rhythms are also intricately linked to memory processing during toddlerhood. These findings are discussed in relation to behavioral changes in memory processes.

Sleep confers a benefit for retention of statistical language learning in 6.5 month old infants

“…In the adult literature theta is related to cognitive and memory load (see Kahana, Seelig, & Madsen, 2001or Klimesch, 1999, for reviews) and more specifically, hippocampal processing (Buzsáki, 2002), successful memory encoding (Sederberg, Kahana, Howard, Donner, & Madsen, 2003), spatial memory (Jones & Wilson, 2005), and consolidation of emotional memory during REM (Fogel, Smith, & Cote, 2007;Nishida, Pearsall, Buckner, & Walker, 2009). Theta and alpha are also linked to better encoding and retrieval in two-year-old children (Cuevas, Raj, & Bell, 2012). However, in the developmental literature, the lack of consistency in identified frequency band ranges reduces the ability to generalize findings across studies (Orekhova, Stroganova, Posikera, & Elam, 2006).…”

Broad implications for respiratory sinus arrhythmia development: Associations with childhood symptoms of psychopathology in a community sample

“…Mothers sat in a chair beside the child and did not interact with the child during the recording. This is a typical baseline for toddler and preschooler electrophysiology research in our laboratory (e.g., Cuevas, Raj, & Bell, 2012; Morasch & Bell, 2012)…”

Using EEG to Study Cognitive Development: Issues and Practices

“…Our recent infant EEG work has attrition rates of 0–12% due to excessive movement artifact or crying (Bell, 2012; Cuevas & Bell, 2011; Cuevas, Raj, & Bell, 2012b). Attrition rates for two- and three-year-old children are higher (30–45%), typically due to refusal to wear the EEG cap, cap removal during the session, or excessive movement artifact (Cuevas, Raj, & Bell, 2012a; Morasch & Bell, 2011; Wolfe & Bell, 2007). Attrition rates drop to 20% by age four as children become more tolerant of the EEG cap and exhibit less movement during recording (Wolfe & Bell, 2004, 2007).…”

“…We prefer the EEG because it also allows an examination of developmental changes without dramatic interference with normal ongoing behaviors. We have used EEG methodology to examine correlations between brain electrical activity and working memory performance during infancy (Bell, 2012, 2001) and early childhood (Wolfe & Bell, 2004, 2007) and recall memory performance during toddlerhood (Cuevas, Raj, & Bell, 2012a). We have also used EEG to describe month-to-month changes in brain development during infancy (Bell & Fox, 1992, 1994; Cuevas & Bell, 2011).…”