1. Sequential Effects on the Oddball P300 in Young and Older Adults
Siri-Maria Kamp
Trier University
Web:
Trier University
Research Priority Program
Psychobiology of Stress
Introduction
Methods
The P300
Commonly captured with „oddball tasks“, where it is elicited by rare „targets“ among frequent „standards“ (e.g. Donchin, 1981)
Amplitude reductions and latency increases (e.g. Polich, 1996) and a more frontal distribution (e.g. Fabiani & Friedman, 1995) in older age
Potential biomarker and predictor of healthy and pathological aging
Do age effects reflect physiological differences (e.g., neural reactivity) or differences in processing the task?
Sequential Effects on P300
P300 amplitude increases with the number of non-targets that precede the target stimulus (e.g. Squires et al., 1976)
Plateau after 4-5 standards
Interpretation: Predictions are derived from a continually updated working memory template of recent information in a limited capacity store. The more unexpected a target based on this template, the larger the P300 amplitude.
Research Goals and Questions
Analyze sequential effects when a large number of standards precede a target, which is common in standard oddball tasks.
Age differences in P300 morphology and P300 sequential effects?
Participants
47 young adults (M=24.73)
50 healthy older adults (M=70.2)
Oddball Task (duration about 20 minutes; part of a 2-3 hour session)
Bernoulli sequence of squares and circles
Rare category: 20%, Frequent category: 80%
Task: “Press a key whenever you see the target stimulus”
3 task blocks with 180 stimuli each
Figure 1: Oddball Task
standard
100 ms ms
(random)
target
Results
Replication of typical overall age differences
Older adults: longer P300 latency, smaller parietal P300 amplitude, larger frontal P300 amplitude (Figures 2 and 3)
Sequential effects (Figures 4 and 5)
Smallest parietal P300 amplitude and a more frontal distribution when a target follows a target (0 preceding standards)
P300 amplitude increase until 3-6 preceding standards
P300 amplitude decrease after 7 preceding standards
Single-trial analysis (Figure 6)
Inverted U-shape in parietal P300 amplitude, depending on preceding standards
Maximum at 4 preceding standards for both young and old adults.
More complex pattern for frontal P300, but still striking similarities between age groups.
Figure 2: Average P300
Figure 3: Scalp Distributions of Average P300
Young
Old
Standard
Target
Difference Fz
Young Pz
Old
Figure 4: P300 to Targets by Number of Preceding Standards
Young
Old Fz
Figure 5: P300 to Targets by Number of Preceding Standards, Relative to the Overall Average P300
1-2
3-6 7+
Young Pz
Old
Figure 6: P300 to Targets by Number of Preceding Standards
Summary and Discussion
preceding standards
Age Differences in P300 and P300 Sequential Effects
The results replicate the typical age-related parietal amplitude decrease, latency increase, and frontal shift
Sequential effects on the parietal P300 were remarkably similar for young and older adults
Age differences in P300 morphology appear to reflect differences in the neurocognitive process itself, rather than differences in the way the sequence is processed.
Interpretation of P300 sequential effects
Rather than reaching a plateau after a certain number of preceding standards, P300 amplitude actually decreases with higher numbers of preceding standards
Inverted U-shape with a maximum at 4 preceding standards for both young and old adults!
Sequential effects on P300 amplitude do not appear to be solely due to expectations derived from a working memory template in a limited capacity store
The target stimulus may gradually change from being mostly „unexpected“ to being more „awaited“ (Verleger, 1988) after several standards have been encountered in a row.
preceding standards
References
Squires, K. C., Wickens, C., Squires, N. K., & Donchin, E. (1976). The effect of stimulus sequence on the waveform of the cortical event-related potential. Science, 193(4258),
Donchin, E. (1981). Surprise!… surprise?. Psychophysiology, 18(5),
Fabiani, M., & Friedman, D. (1995). Changes in brain activity patterns in aging: the novelty oddball. Psychophysiology, 32(6),
Verleger, R. (1988). Event-related potentials and cognition: A critique of the context updating hypothesis and an alternative interpretation of P3. Behavioral and brain sciences, 11(3),
Polich, J. (1996). Meta‐analysis of P300 normative aging studies. Psychophysiology, 33(4),