Using the P300 Potential for the Analysis of Cognitive Functions in Children

In 84 healthy 5- to 15-year-old children, we studied the cognitive components of the evoked potentials elicited by acoustic stimulation, the P300 wave generated after presentation of a sign stimulus requiring the performance of sensorimotor reaction. We found a linear dependence of the peak latency of the P300 on the age of the tested persons (the latencies decreased with age). The amplitude of the P300 wave exhibited no clear dependence on the age (obviously, this parameter to a greater extent depends on other factors).     

Radiation Processed Amniotic Membranes in the Treatment of Non-Healing Ulcers of Different Etiologies

The amniotic membranes were collected from the placentae of selected and screened donors. Processing was done by washing the fresh amniotic membrane successively in sterile saline, 0.05% sodium hypochlorite solution and sterile distilled water until it was completely cleared of blood particles. The membranes were sterilized by gamma irradiation at 25 kGy. The processed amniotic membranes were applied to 50 open wounds comprising of 42 full thickness defects and eight partial thickness defects. These included leprotic, diabetic, traumatic, gravitational ulcers and superficial burn in the form of scald and corrosive burn. The radiation processed amniotic membranes favoured healing of unresponsive and non-healing ulcers of different etiologies. Ulcers with duration of minimum 3 weeks to maximum 12 months were found to heal in 2-6 weeks by the application of amniotic membranes.     

Oxidative Parameters in the Rat Brain of Chronic Mild Stress Model for Depression: Relation to Anhedonia-Like Responses

The chronic mild stress (CMS) protocol is widely used to evoke depression-like behaviors in the laboratory. Some animals exposed to CMS are resistant to the development of anhedonia, whereas the remaining are responsive, CMS-resilient and CMS-sensitive, respectively. The aim of this study was to examine the effects of chronic stress on oxidative parameters in the rat brain. The consumption of sweet food, protein and lipid oxidation levels and superoxide dismutase and catalase activities in the rat hippocampus, cortex and cerebellum were assessed. We found a significant increase in protein peroxidation (hippocampus and cortex), a significant increase in catalase activity (cortex, hippocampus and cerebellum) and a decrease in superoxide dismutase activity (cortex, hippocampus and cerebellum) in the CMS-sensitive group compared to the CMS-resilient group and normal controls as well as an increase in lipid peroxidation (cerebellum) in the CMS-sensitive and CMS-resilient groups compared to normal controls. However, there was no significant difference in protein peroxidation (cerebellum) and lipid peroxidation (cortex and hippocampus) among the three groups. In conclusion, our results indicate that the segregation into CMS-sensitive and -resilient groups based on sucrose intake is paralleled by significant differences in oxidative parameters. CMS induces oxidative damage and alterations in the activity of antioxidants which may lead to increased oxidative damage, irrespective of the anhedonia-like status of the stressed animals.     

Brain fingerprinting field studies comparing P300-MERMER and P300 brainwave responses in the detection of concealed information

Brain fingerprinting detects concealed information stored in the brain by measuring brainwave responses. We compared P300 and P300-MERMER event-related brain potentials for error rate/accuracy and statistical confidence in four field/real-life studies. 76 tests detected presence or absence of information regarding (1) real-life events including felony crimes; (2) real crimes with substantial consequences (either a judicial outcome, i.e., evidence admitted in court, or a $100,000 reward for beating the test); (3) knowledge unique to FBI agents; and (4) knowledge unique to explosives (EOD/IED) experts. With both P300 and P300-MERMER, error rate was 0 %: determinations were 100 % accurate, no false negatives or false positives; also no indeterminates. Countermeasures had no effect. Median statistical confidence for determinations was 99.9 % with P300-MERMER and 99.6 % with P300. Brain fingerprinting methods and scientific standards for laboratory and field applications are discussed. Major differences in methods that produce different results are identified. Markedly different methods in other studies have produced over 10 times higher error rates and markedly lower statistical confidences than those of these, our previous studies, and independent replications. Data support the hypothesis that accuracy, reliability, and validity depend on following the brain fingerprinting scientific standards outlined herein.     

Differences in the P300 Parameters, Neuropsychological Profile, and Cognitive Impairments in Patients with Cortical and Subcortical Dementia

In this study we analyzed the parameters of auditory evoked potentials in a stimulus recognition task (the P300 method) and nonspecific visual response to a light flash in 75 healthy subjects of various ages (20–70 years) and 70 subjects (35 males and 35 females, mean age 51 years) with cortical and subcortical cognitive impairments of various degrees (cerebrovascular disorder) with different neuropsychological profiles. It was shown that parameters of the P300 complex depend on both the subject age and his/her cognitive functions and can be used for objective analysis of cognitive impairments. An inverse relationship between the P3 (P300) peak latency and the volume of short-term and operative memory in subjects with cognitive impairments was found. The parameters of the nonspecific visual response (duration and the maximum amplitude), reflecting functioning of the arousal systems of the brain, depended on the type and severity of cognitive impairments but did not depend on the subject's age. Differences in the neuropsychological profiles of cognitive impairments and the pathophysiological mechanisms of their development, reflected by parameters of the evoked potential, as well as differences between the brain structures involved in these process, substantiate the discrimination of two types of cognitive impairments—cortical and subcortical—in subjects with cerebrovascular disorders.     

The Role of Intention to Conceal in the P300-based Concealed Information Test

The present study examined whether intention to conceal knowledge affects P300 amplitude and detection accuracy in the concealed information test. Eighteen university students were told to choose one card from five and to hide it. In the conceal condition, participants made an effort to leave their chosen card undetected by suppressing their brain response to it. In the transmit condition, they attempted to inform the experimenter of the chosen card by enhancing brain response to it. In the no secret condition, participants showed the chosen card to the experimenter beforehand and lost their motivation to conceal it. The difference in P300 amplitude between the chosen and unchosen cards was significant only in the conceal and transmit conditions. The results suggest that a larger P300 amplitude for the chosen card was not due to a deception-specific process but rather to increased significance of the item caused by additional processing.     

Novel Neuroprotective Potential of Crocin in Neurodegenerative Disorders: An Illustrated Mechanistic Review

Neurochemical Research - Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal...     

Adaptation to the complexity of a task (a P300 study)

In numerous studies the P300 component of the event-related brain potential (ERP) has been shown to occur in connection with stimulus evaluation processes. 10 healthy right-handed volunteers (3 women, 7 men) aged from 25 to 30 years (mean age 27.8 years) participated in the experiments. One of 5 equiprobably occurring two-letter strings appeared on the screen always at the same central location. The strings informed the subjects about the difficulty of subsequently presented mental arithmetic tasks. After the letter strings vanished from the screen the subjects were to press the space-bar whereby a mental arithmetic task was presented corresponding in difficulty to the preceding message. The EEG was recorded by means of Ag/AgCl electrodes from frontal (F zeta), central (C zeta) and parietal (P zeta) midline electrodes referenced to linked earlobes. EEG and EOG were sampled 1200 ms, starting 200 ms prior to string onset. P300 peak latencies, peak amplitudes and areas in the time range 300 to 900 ms were measured in ERPs averaged selectively for the 5 strings. The main finding was that the P300 amplitude in ERPs to the 5 different strings varied in a U-shaped trend as a function of announced task difficulty. This result gives further evidence that the P300 amplitude reflects distance between incoming information and current adaptation level at the inferred internal dimension, i.e. task difficulty in this experiment.