P300 Wave Latency and Amplitude in Healthy Young Adults: A Normative Data
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.344641
Source of Support: None, Conflict of Interest: None
Keywords: Cognition, electroencephalography, event-related potential, healthy adults
Electroencephalography (EEG) recording of the human brain was first recorded in 1924 by the German physician Hans Berger, which has shown path for various scientific breakthroughs and clinical applications.In the electrical activity estimating methods of the human brain, the evoked potential (EP) approach possesses great importance for investigating brain mechanisms responsible for higher brain functions.Graphical recording of human brain activities by scalp electrodes area noninvasive method and sensitive tool of ongoing brain activity while resting state and during cognitive tasks.Electrical activities can be recorded as continuous EEG during the resting state, reflects the mental states, and time-locked event-related brain activity, while cognitive tasks that can be analyzed in the time slot as event-related brain potentials (ERPs) reflect neural processing.ERPs are miniature voltages provoked in the brain structures in response to particular stimuli and events. These EEG changes can be used to study psycho physiological correlates of mental processes. Different types of sensory, cognitive, or motor events can be used to develop ERPs. During the processing of information, a large number of relatively oriented cortical pyramidal neurons also fire in synchronicity, reflecting the summation of postsynaptic potentials produced. ERP recordings can be classified into two groups. The early waves occur at about 100 ms after stimulus which termed as “exogenous”, and waves produced in later parts indicate the pattern in which the subject evaluates the stimulus and is termed as “endogenous.” Exogenous mainly depends on the physical parameters of the stimulus and endogenous on persons evaluation but the ERPs as they examine information processing.Recording brain activity in humans using scalp electrodes provides a nonintrusive, measure of ongoing brain function during resting state and during cognitive tasks.
Sutton et al. (1965) introduced the P300 (P3) wave, since then it has been the vital component of research of ERP.Auditory stimuli among 20–70 years age group; the latency range is 250–400 ms. The P300 wave latency reflects the speed of stimulus resulting from discrimination of one event from other event. P3 amplitude reflects stimulus interpretation such that greater attention yields larger P3 waves. Oddball paradigm is the most commonly utilizing paradigm in P300 studies when different stimuli are presented in a series; one of them occurs relatively rarely, which is the oddball. The subject is instructed to respond to the rare or target stimulus and not to the frequently stimulus. Reduction of P300 amplitude is also indicator of the broad neurological problems that underlie within the externalizing spectrum.P300 is a sensitive tool for indicating cognitive decline analysis., Reduced cognitive processing is seen with ageing, which is characterized by increased in latency and decreased in amplitude.So the main objective of present study is to generate the normative data of P300 wave latency and amplitude in healthy young adults of 18–25 years age group in healthy young adults.
The present study was conducted at the Neurophysiology Laboratory of the Physiology Department at RUHS College of Medical Sciences, Jaipur. Institute's ethics committee approval (EC/P47/2018) was taken before the start of the study. Healthy controls were selected in the study. These healthy controls were students of the Institute who were recruited in sample and give willingly consent. Hundred healthy young adults age (18–25 years) were recruited, Anthropometric measurements (height, weight, and BMI) were recorded and then analyzed for P300 using auditory oddball paradigm [Octopus NCV/EMG/EP-4 Channel Machine (Model name: CMEMG 01)].
The whole test procedure was conducted in a silent acoustic room of Neurophysiology lab. The data were collected early in the morning. Subjects were asked to sit down comfortably and advised not to sleep during the test procedure. Electrodes were placed on scalp. The positions of electrodes are given in [Figure 1].
Reference electrode: Reference electrode was placed on the Cz position of scalp.
Active electrode: Two active electrodes were placed on each mastoid process (A1 and A2).
Ground electrode: Ground was placed on the Fpz position [Figure 1].
Subjects were also asked to wear a headphone, through which they heard the rare and frequent tones of different loudness or pitch. Also, subjects were instructed to recognize the rarer type of the tone and raise the finger with the dominant hand each time they heard it. They were instructed to close their eyes and not to sleep during the whole test procedure [Figure 2]. Thus, data were recorded.
Normally, distributive data presented in the form of mean, standard deviation, and Pearson correlation were analyzed to see the correlation in MS-Excel 2007.
Mean values of demographic data are listed in [Table 1]. Also, the latency and amplitude data of participants are displayed in [Table 1].
There was a significant positive correlation between P300wave latencies with age. However, with BMI, the latency has almost negligible correlation. P300 latency was mildly correlated with amplitude [Table 2].
P300 is a sensitive tool for monitoring cognition and maybe an indicator in the analysis of cognitive deterioration.,,,, P300 latency and amplitude are often considered to be importantly related to higher cortical functioning. A decrease in amplitude and increase in latency correspond to cognitive decrement. This study was designed to generate normative data of P300 latency and amplitude of normal young healthy adults. The latency and amplitude were lower than the study done by Uvais et al.Some variability in P300 amplitude and latencies across studies could be due to several factors including food intake, body temperature, and handedness.Further, study parameters in eliciting P300 including the task, paradigm type, types of stimulus, and software used may also affect the values. Thus, it may be desirable to have normative data of young population. It would be also worthwhile to have standardized protocols for conducting ERP studies to make the comparison with reference values meaningful.P300 latency usually decreases during the first years of human life,but in older adults, the parietal P300 latency increases.There was significant correlation of age with P300 latency. BMI and P300 amplitude were inversely correlated with P300 latency, but results were not significant. The P300 latency possibly indicates the neural speed or mental capability. The P300 amplitude possibly indicates cognitive resources or neural strength, which increase with the advancement of age. Agarwal S et al. concluded that no association was observed between BMI and cognition. Dinteren R et al. suggested that latency and amplitude reflect different aspects of brain maturation. Specifically, the P300 amplitude might be an index for the amount of cognitive capability being used, increasing in the early stages of development, and decreasing with further increase in age beyond adolescence.
This study results reflected normative data of P300 wave latency and amplitude in healthy young adults of 18–25 years age group.
We would like to thanks all the medical students and technical staff of RUHS, Jaipur.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2]
[Table 1], [Table 2]