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Biomedical subjects

J Polich

Publications and source records attributed to J Polich.

At least 109 records · Page 6Linked to original sources
PubMed1990

Normal variation of P300 in children: age, memory span, and head size.

The P300 (P3) event-related brain potential was elicited in a group of 50 children and young adults (4-20 years). A simple auditory task was employed in which subjects indicated with a finger movement when a randomly occurring target tone (high pitch) was presented in a series of standard (low pitch) tones. The probability of the target tone was varied across conditions at 10%, 30%, or 50% to assess possible developmental changes in P300 amplitude. Memory capacity was assessed with forward and reverse digit spans. Circumference of the head also was measured. P300 latency decreased with age, and P300 amplitude tended to become larger with age. Polynomial regression analyses revealed significant quadratic trends in these relationships, with changes leveling off for older subjects. Digit span and head circumference also were related curvilinearly to P300 values. Multiple regression analysis indicated that changes in age and memory span both predicted significant changes in P300 latency and amplitude. Target stimulus probability generally affected all subjects in a similar fashion, although the strength of the correlational relationships tended to decline with increases in probability. Developmental changes for the N1, P2, and N2 components from the standard stimuli also were obtained. The results are discussed in terms of previous P3 findings for children and their implications for future studies.

Acoustic Stimulation↗
PubMed1990

P300 and time of day: circadian rhythms, food intake, and body temperature.

The P300 or P3 component of the event-related brain potential (ERP) was obtained from five groups of 24 young adult subjects, with each group measured at a different time of day (8 a.m., 11 a.m., 2 p.m., 5 p.m., 8 p.m.). An activity-preference questionnaire was used to ensure that an equitable number of morning- and evening-preferring subjects were obtained for each testing time. P3 measures, physiological (body temperature, heart rate, subjective alertness), and cognitive performance (digit span, prose memory, digit symbol) variables were assessed. P3 amplitude and latency were not affected directly by the time of day. However, P3 amplitude was smaller in subjects who had not eaten within 6 hours of testing relative to subjects who had a recent meal, and P3 latency was correlated negatively with body temperature. The findings suggest that although the P3 ERP is not influenced by circadian rhythms, it is related to recency of food intake and physiological factors which change with time of day.

Adolescent↗
PubMed1990

P300, probability, and interstimulus interval.

The relationship between target stimulus probability and interstimulus interval on the P300 (P3) component of the event-related potential was assessed in three experiments. In each study an auditory discrimination paradigm was employed wherein subjects indicated with a finger tap response the occurrence of a randomly presented 2000 Hz target tone embedded in a series of 1,000 Hz tones. Target stimuli were presented with a probability of either .20 or .80 in different conditions which were combined factorially with different interstimulus intervals. Experiment 1 presented stimuli at 2.0, 2.5, or 3.0 second intervals; Experiment 2 presented stimuli at 2.0, 3.0, or 4.0 second intervals; Experiment 3 presented stimuli at 4.0, 6.0, or 10.0 second intervals. P3 amplitude was larger for the .20 relative to the .80 target probability conditions for the shorter interstimulus intervals but not for the longer intervals. P3 latency was consistently longer for the .20 relative to the .80 target probability conditions, with generally little effect observed for interstimulus interval changes. The results suggest that interstimulus interval affects component amplitude by determining the amount of processing resources available when the P3 is produced.

Adult↗
PubMed1990

Noninvasive trigeminal evoked potentials: normative data and application to neuralgia patients.

A mild electric shock applied to the lower lip was used to elicit reliable evoked potentials from the trigeminal nerve in 20 normal young adults. The wave forms were morphologically similar to those observed with invasive procedures. No substantial differences for either the right or left side of stimulation, recording electrode, or subject sex were obtained for any of the individual potential amplitudes or latencies. The same procedures were applied to 10 patients who had been treated with retrogasserian glycerol injections for trigeminal neuralgia. Trigeminal evoked potentials were elicited in all patients, although the quality of the individual wave forms was more variable than that observed for the normal subjects. Comparison of the treated with the unaffected face side in the patients demonstrated significantly smaller N2-P2 amplitudes and longer N2 latencies for the affected face side. The results suggest that these procedures produce reliable evoked potential measures of trigeminal nerve function noninvasively which can provide an objective index of treatment efficacy.

Adult↗
PubMed1989

P300 and probability in children.

The P300 event-related brain potential (ERP) was elicited in three groups of 12 children each, ages 5-9, 10-14, and 15-19 years. A simple auditory task was employed in which subjects indicated with a finger movement when a randomly occurring target tone (high pitch) was presented in a series of standard (low pitch) tones. The probability of the target tone was varied across conditions at 0.10, 0.30, or 0.50 to determine if P300 amplitude would respond similarly across age groups. Immediate memory capacity was measured with forward and reverse digit spans. P300 amplitude increased with decreases in target stimulus probability for each age group and also tended to become larger with age. P300 latency decreased in the same fashion across probability levels as age increased. Digit span demonstrated the usual increase with age. The results suggest that cognitive development is indexed by decreases in P300 latency, and that P300 amplitude changes from the probability of the target stimulus are similar across age groups. The implications for the theoretical interpretation of the P300 and application of ERPs for evaluating cognitive development are discussed.

Adolescent↗
PubMed1989

P300 and Alzheimer's disease.

Previous studies using the P300 or P3 component of the event-related brain potential (ERP) to study dementing illness are reviewed and recent results on the application of P3 techniques for the diagnosis of early Alzheimer's disease are presented. These data suggest that the P3 ERP can aid in the diagnosis of dementia and may help in the assessment of early Alzheimer's disease.

Alzheimer Disease↗
PubMed1989

Frequency, intensity, and duration as determinants of P300 from auditory stimuli.

The auditory event-related potential was assessed in two experiments that evaluated the effects of stimulus factors on P300 (P3) component amplitude and latency. The first experiment manipulated the frequency of the target stimuli (500, 1,000, 1,500, and 2,000 Hz) and standard stimuli (250 and 4,000 Hz) in different conditions. Both P3 amplitude and latency were affected by the target and standard tone combinations in specific ways. The second experiment varied the target tone intensity and duration factorially. P3 amplitude was unaffected by these variables, but peak latency was significantly shorter for the loudest and longest target stimuli. The findings indicate that variation in auditory stimulus parameters can produce small but reliable effects for P3 values, which should be considered when results are compared across studies.

Adolescent↗
PubMed1988

P300 latency after ethanol ingestion in sons of alcoholics and in controls.

The magnitude and persistence of ethanol-induced increases in the latency of the P3 event-related potential from auditory stimuli were evaluated in 21 sons of alcoholic fathers (FHP) and 21 control sons of nonalcoholics (FHN) matched on demography and drinking history. The men were assessed at baseline, 70 min after imbibing a beverage, and 240 min after drinking, with observations carried out for each individual in 3 dosage conditions (placebo, 0.75 ml/kg of ethanol, and 1.1 ml/kg of ethanol). There were no family group differences for baseline (prechallenge) P3 latencies, nor any significant group differences after placebo or low-dose ethanol challenges. However, in the high alcohol dose challenge condition, P3 latencies for FHP subjects returned toward baseline measures more quickly than for FHN men. These results are consistent with previous reports of behavioral and biochemical measures in which FHP subjects demonstrated less intense reactions or returned toward baseline conditions more rapidly after ethanol ingestion relative to the FHN controls.

Adult↗
PubMed1988

P300 and the word frequency effect.

In a lexical decision paradigm subjects viewed character strings and indicated if they were true words. Half of the stimulus words occur frequently and half occur infrequently in printed English. The probability that a stimulus was a true word varied across conditions. Event-related brain potentials (ERPs) and reaction time (RT) were recorded. The latency of the P300 ERP was used to estimate stimulus evaluation time independently of factors influenced by response selection and execution. Uncommon words were associated with longer P300 latencies, reduced P300 amplitude, and slower responses. The probability of a stimulus being a true word in any given sequence affected RT, but produced only small effects on P300 latency. The results suggest that: (1) the effects of word frequency originate early during processing, (2) stimulus probability affects response priming mostly for stimuli which do not evoke a high-level code, and (3) uncommon words require more processing capacity for their evaluation than common words. The results are discussed in the context of word recognition models.

Adult↗
PubMed1988

Hemispheric differences for visual evoked potentials from checkerboard stimuli.

Visual evoked potentials (VEPs) were elicited in right-handed male subjects with an alternating checkerboard pattern stimulus presented to either the left or right visual half-field. The sizes of the individual checks in different conditions were 0.25, 0.5, 2.0, or 4.0 cycles/degree of visual angle. The amplitude of the P100 VEP decreased while peak latency increased as check size decreased across both visual field conditions. Left hemisphere responses demonstrated significantly larger P100 amplitudes compared to the right hemisphere responses, although the interaction between hemisphere and stimulus size was not significant. No hemispheric effects of P100 latency were observed. The results suggest that the left hemisphere is engaged more than the right hemisphere for the sensory analysis of visual stimuli composed of straight edges over a wide range of spatial frequencies.

Adult↗
PubMed1988

Hemispheric differences for orthographic and phonological processing.

The role of hemispheric differences for the encoding of words was assessed by requiring subjects to match tachistoscopically presented word pairs on the basis of their rhyming or visual similarity. The interference between a word pair's orthography and phonology produced matching errors which were differentially affected by the visual field/hemisphere of projection and sex of subject. In general, right visual field/left hemisphere presentations yielded fewer errors when word pairs shared similar phonology under rhyme matching and similar orthography under visual matching. Left visual field/right hemisphere presentations yielded fewer errors when word pairs were phonologically dissimilar under rhyme matching and orthographically dissimilar under visual matching. Males made more errors and demonstrated substantially stronger hemispheric effects than females. These patterns suggested visual field/hemispheric differences for orthographic and phonological encoding occurred during the initial stages of word processing and were more pronounced for male compared to female subjects.

Adolescent↗
PubMed1988

P300 and the risk for alcoholism: family history, task difficulty, and gender.

P300 event-related brain potentials (ERPs) were obtained from 20 pairs of male and 20 pairs of female undergraduate subjects. One member of each pair reported having a father who was alcoholic (FHP), the other reported no known alcoholic biological relative (FHN). Pair members were matched on age, height, weight, grade point average, and personal drinking history. Three auditory tasks which differed in stimulus discrimination difficulty were presented to each subject. All tasks employed 20% target and 80% standard tones with the subject required to move their index finger whenever a target stimulus was detected. No significant differences in P300 amplitude or latency were obtained between the family history subject groups, although female FHP subjects tended to have smaller P300 amplitudes than their FHN counterparts. P300 amplitude decreased with increases in the amount of self-reported alcohol consumed for FHP subjects but significantly so only for the most difficult task situation. The results suggest that the relationship between the P300 ERP and the inheritability of alcoholism is not yet clear and may be subject to modulation by task requirements, population differences, and subject sex.

Adolescent↗
PubMed1988

Event-related brain potentials in individuals at high and low risk for developing alcoholism: failure to replicate.

Event-related brain potentials (ERPs) were used to compare young men having a positive paternal family history for alcoholism (FHP) with carefully matched control subjects having no family history for alcoholism (FHN). The P300 ERP component was obtained from all subjects (n = 10/group) with a complex auditory paradigm before and on two occasions after they received a placebo drink which they were told might contain alcohol. The procedures employed replicated those of a previous study in which FHP subjects showed diminished P300 potentials compared to FHN subjects under the placebo as well as ethanol consumption conditions--a finding which raised the possibility that the P300 ERP component might be a biological marker for subjects at high risk to develop alcoholism. No differences between the family history groups were obtained for the P300 or any other ERP component using the replication procedures. Both groups demonstrated a decrease in P300 amplitude across trial blocks in a similar fashion suggesting that habituation effects may have diminished the ERP response.

Adult↗
PubMed1988

Assessment of young men at risk for alcoholism with P300 from a visual discrimination task.

A visual discrimination paradigm was used to elicit the P3 (P300) component of the event-related brain potential (ERP) in a large group (N = 196) of male undergraduate volunteers. Comparison of P3 amplitude and latencies between individuals with a positive family history for alcoholism (FH +) and those without such a history (FH -) obtained no differences between the groups. No associations between P3 latency or amplitude and the amount of alcohol typically consumed were found. Differences between the present and previous P3 family history studies using visual stimuli are attributed to the cognitive demands of ERP task.

Adult↗
PubMed1988

Bifurcated P300 peaks: P3a and P3b revisited?

The P300 (P3) component of the event-related brain potential (ERP) was elicited with an auditory discrimination paradigm in a large group (n = 100) of undergraduates. Subjects who displayed bifurcated P3 peaks across trial blocks (n = 35) were classified into three groups based on the consistency of the replication of the two P3 subpeaks. Amplitude and latency measures for the first (P3a) and second (P3b) peaks from each subject demonstrated no statistically reliable differences between groups. Both subcomponents increased in amplitude from the frontal to parietal electrode sites, although the earlier peak was smaller at the frontal electrode site for the second compared to first trial block. The largest P3 peak for each trial block (P3MAX) from each subject was measured and produced amplitude and latency values that closely matched normative data from the same paradigm. The findings suggested that the P3a and P3b subcomponents from auditory stimuli may be distributed in the population in an asymmetric fashion, and that the P3MAX measurement technique provides a reasonable means of assessing amplitude and latency values from individuals with bifurcated peaks.

Action Potentials↗
PubMed1987

P300 from identical twins.

The P300 component was obtained from ten pairs of identical twins and matched control subjects with an auditory discrimination task. The event-related brain potentials (ERPs) from the identical twins were strikingly similar in amplitude and latency compared to control subject pairs. The data suggest that individual variations in ERP waveform morphology are determined by the structure of the neurophysiological mechanisms responsible for P300 generation.

Adolescent↗
PubMed1987

Task difficulty, probability, and inter-stimulus interval as determinants of P300 from auditory stimuli.

The P300 event-related potential was elicited with auditory stimuli in 4 experiments which manipulated combinations of stimulus target probability (10% vs. 30%), task difficulty (easy vs. hard), and inter-stimulus interval (5 sec vs. 2 sec). P300 amplitude was smaller and peak latency longer for the more difficult relative to the easier tasks across experiments. Increases in stimulus target probability generally diminished P300 amplitude and shortened peak latency more for the easy relative to difficult task conditions. Increasing the number of non-target stimulus tones decreased P300 amplitude reliably, but increased latency only slightly. Task difficulty did not interact with variations in inter-stimulus interval which produced generally weak effects for both amplitude and latency. These findings suggest that P300 amplitude and latency obtained from auditory discrimination paradigms reflect processing difficulty independently of stimulus target probability unless differences in task requirements affect stimulus encoding.

Adult↗