• Abstract 

• Introduction

  • Rare events elicits large P300 

  • Largest at parietal electrode 

  • Amplitude is affected by probability of stimulus 

  • Can say that surprising events cause a bigger stimulus but does not constitute a theory of P300

  • P300 is a significant positive deflection in the EEG signal

  • Occurs around 300 ms post stimulus 

  • Linked in cognitive processes such as attention and memory 

• Specifications for P300 theory 

  • Rarer the event → larger the P300 

  • *can’t necessarily say its a surprise 

• Methods 

  • Subjects were exposed to auditory stimuli categorized by standard (frequent) or “target” (infrequent) 

  • Probability of occurrence was manipulated to create expectancy 

• Conclusions

  • Larger P300 amplitudes recorded for rare (target stimuli) compared to frequent 

  • P300 is a marker for cognitive processing related to attention 

  • Reflects brain's response to surprising or novel events 

  • P300 is a tool for understanding cognitive functions 

  • Suggests applications in both research and clinical settings for evaluating cognitive processing 

Updating P300: An integrative theory of P3a and P3b

• Fundamental P300 issues 

• Neuropsychological background 

• fMRI on P300 origins 

• Neuropharmacological processes 

• Model system for P3a and P3b to result from operation of inhibitory mechanisms engaged by incoming stimulus events to facilitate memory processing 

• Oddball paradigm: presentations of sequences of repetitive stimuli are infrequently interrupted by a deviant stimulus 

• Amplitude: difference between mean pre-stimulus baseline voltage and the largest positive-going peak of the ERP waveform with a time window

• Distractor elicits a P3a and a target elicits and P3b 

• P300 arises from the interaction between the frontal and parietal lobes 

• Regular stimulus elicited N100, P200, N200 

  • Diff stimulus elicits them all 

• Introduction 

  • P3a is from stimulus-driven frontal attention mechanism during task processing and P3b is from temporal-parietal activity associated w/ attention and memory processing 

  • P3a is frontal/dopaminergic and P3b is partial/norepinephrine pathways 

  • *neural inhibition is one of the mechanisms for P300 when stimulus is activated 

• Theory 

  • P300 indexes brain activities involved in revising mental representations induced by incoming stimuli.

  • P300 is sensitive to attentional resource allocation and overall arousal

  • Greater task demands results in smaller P300 amplitudes and longer latencies as processing resources are allocated to task performance 

  • Target to target interval: short intervals result in smaller P300 components compared to longer intervals → temporal limitations in the P300 amp may stem from memory trace development governing event 

  • P300 amp is smaller for relatively rapid stimulus and increases with longer intervals indicating a link between P300 and attentional processing 

    • Shorter latencies are associated with superior cognitive performance 

  • *influenced strongly by genetic factors w/ EEG spectral characteristics highly similar among biological family members 

  • Variations are linked to personality attributes, attentional resource capabilities and neurotransmitter functions 

• Neuropsychology of P3a and P3b 

  • P3a is elicited by infrequent distractor → initiated by frontal lobe 

  • Different types of distractors and task demands determine component amplitude and characteristics 

  • P3b may be more related to subsequent attentional resource activations and memory operations in temporal-parietal areas 

• P3a vs P3b 

  • A

    • Infrequent distract stimulus w/o a task 

  • B 

    • Elicited during target stimulus processing tasks 

    • Participant is actively engaged 

    • Longer peak latency 

    • Related to memory operations 

    • More strongly related to response time over parietal areas 

      • Stronger association w/ cognitive processing and response organization 

• Neuropharmacology 

  • PD show deficient P300 measures due to increased dopamine levels 

  • Dopaminergic agents affect P300 amplitude and latency 

  • Kids at risk for alcoholism exhibit P300 deficits 

  • Norepinephrine system contributes to P3b gen

    • Linked to partial P300 generation for target detection tasks 

  • Animals studies support the involvement of LC-NE in P300 generation  → aligning w/ attention resource allocation and arousal-related effects 

• What does the P300 do 

  • P300 results from brain mechanisms engaged to inhibit extraneous brain activation 

  • Hypothesis suggests that the P300 and its subprocesses reflect rapid neural inhibition of ongoing activity to facilitate the transmission of stimulus/ task information 

  • Signals originate from the need to enhance focal attention during stimulus detection relative to contents of working memory 

  • Latency indexes the celerity with which extraneous processes are inhibited → associated w/ intelligence 

  • Declines stem from breakdowns of cortical processes 

P300 Clinical Utility and Control of Variability

• Determine if P300 can be used as a clinical assay by comparing its distribution qualities with normative biomedical testing data 

• Coefficient of variation statistic reveals highly comparable and superior variability of P300 amplitude and latency → capture a broader range of cognitive responses 

• Usefulness has been limited bc of absence of established normal component values and standard method for acquisition 

• Prolonged P300 latency is presenting in people w/ dementing illness as an index of cognitive function although its diagnostic value is questioned 

  • Can help differentiate between types of dimensions 

• Amplitude: index brain activity required in the maintenance of working memory and proportional to the amount of attentional resources devoted to a task 

• Latency: measure of stimulus classification speed and is independent of behavioral reaction time 

  • Make it a sensitive temporal measure of neural activity underlying attention allocation and memory 

  • *talks about how quickly the brain processes and categorizes incoming stimuli 

    • How rapidly the brain identifies and classifies the significance or meaning of a stimulus within a given task context 

  • *behavioral planning time is also affected by motor planning and execution 

  • Can see how fast their brain is working even if their body isn’t function 

• Factors affecting P300 variability include circadian rhythms, body temperature, heart rate, food intake, activity level, fatigue, drugs, age, intelligence, handedness, gender, personality, and genetics.

• Methods 

  • Coefficient of variation provides a standardized measure of variability by comparing the standard deviation to the mean of a dataset 

  • Smaller CV is peaked and large CV is flatter 

  • Compares inherent variability among different types of measurements 

• Results 

  • Amplitudes exhibited larger CV values compared to latency

  • Auditory stimuli has larger CV values 

  • Latency was more consistent across electrodes by amplitudes varied across scalp locations → smaller values and midline and parietal locations 

• Discussion 

  • Alzheimer's: studies show that P300 can discriminate against diseases 

  • Simplification may need a single-stimulus paradigm 

  • *needs to be revisited 

The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children

• Introduction 

• Previous research indicates aerobic fitness and BMI are negative but it is related with better performance 

  • Muscle strength and flexibility are unrelated 

• Amplitude: index allocation of attention resources during stimulus engagement 

• Latency: index stimulus classification and evaluation speed w/ increased latency reflecting longer processing time 

• Acute exercise on P3 have observed increased amplitude 

• Methods 

• 20 right hand

• KBIT for IQ 

• Around age 9 

• Completed modified flanker 

• EEG 

• Did the WRAT → designed to produce two equivalent administrations 

• VO2

• Discussion 

• Response accuracy is more sensitive 

• Found no difference ? 

• P3 increased follow exercise 

• acute exercise was associated with better performance in reading achievement tests, indicative of a potential full-grade level increase. 

Aerobic Fitness and Neurocognitive Function in Healthy Preadolescent Children

• Underlying reasons why for fitness improves academic achievement are unclear 

• Aerobic exercise is associated w/ greater P3 amplitude and faster P3 latency 

• Study investigated relationship between high and low fit groups based on the Fitnessgram testing 

• Demographic data was collected 

• *high fit children had greater P3 amplitude compared to low-fit children and faster P3 latency 

  • Also had faster reaction times 

  • Increased recruitment of neurons for the task 

• Largest amplitude was at the central and parietal sites 

• Non-target stimuli elicited faster latency than target stimuli at parietal sites.

  • Makes sense the target stimulus is the unknown stimulus (cats vs. dogs) 

• High-fit participants demonstrated faster P3 latency at occipital sites.

• Fitness may be associated w/ increasing neuroelectric activation related to attention and working memory resources, potentially influencing the speed of behavioral performance 

• Next step: use aerobic exercise as an intervention for an experiment instead of a cross-sectional survey 

Effects of the FITKids Randomized Controlled Trial on Executive Control and Brain Function

• Executive control: consists of inhibition, working memory, cognitive flexibility 

  • Vital to success in schools 

  • Peak commonly used to assess brain activity is the P3 

    • Reflects neuron activity thought to be associated with the process attention and working memory and can be assessed relative to its size (measured in amplitude) and its timing (measuring in latency) 

• Population: 8-9 year olds residing in East Central Illinois

• Task: modified flanker task 

• Intervention group 

  • greater improvement from pretest to posttest than the wait-list control group   

  • Increased P3 amplitude from pretest to posttest on incongruent trials 

  • Faster P3 latency (shorter ?)