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Biomedical subjects

J Polich

Publications and source records attributed to J Polich.

At least 73 records · Page 4Linked to original sources
PubMed1996

P300 topography and modality effects from a single-stimulus paradigm.

The P300 event-related brain potential (ERP) was elicited with auditory and visual stimuli in two different tasks. The oddball paradigm presented both target and standard stimuli; the single-stimulus paradigm presented a target but no standard stimulus, with the intertarget interval the same as that for the oddball condition. Target probability was .20 for the oddball task, with target stimuli occurring at the same temporal frequency in the single-stimulus paradigm. Scalp topography was assessed with 15 electrode locations. P300 amplitude was larger and latency was longer for the oddball than for single-stimulus procedure. P300 from auditory stimuli was smaller and shorter in latency than that from the visual stimuli, and both modalities showed similar but not identical scalp topographies. The findings suggest that the single-stimulus paradigm may be useful in experimental and applied contexts that require very simple ERP task conditions.

Acoustic Stimulation↗
PubMed1995

P300 from auditory stimuli: intensity and frequency effects.

Auditory stimulus intensity (45, 60, 75 dB SPL) and standard/target frequency (250/500) and 1000/2000 Hz) were manipulated factorially to assess their effects on the P3(00) event-related brain potential (ERP). For the target stimuli, intensity increases produced reliable increases in P3 amplitude and decreases in peak latency. P3 latency at the lowest intensity level was marginally longer for the low frequency condition. For the standard stimuli, intensity increases produced reliable P3 amplitude increases, low frequency stimuli yielded smaller components than high frequency stimuli, and several interactions with the electrode factor were obtained. P3 latency decreased as intensity increased, and low frequency tones produced longer latencies than high frequency tones. The N1, P2, and N2 components from both stimulus types generally were affected in the same manner: intensity increases producing larger amplitudes and shorter latencies, with some effects of tone frequency also observed. The findings suggest that auditory stimulus parameters contribute to both P3 amplitude and latency measures in important ways and are discussed in relation to the use of ERPs in applied contexts.

Adult↗
PubMed1995

Spectral analysis of EEG from families.

Electroencephalographic (EEG) activity was obtained under eyes open and eyes closed conditions from ten families, each consisting of a biologically related father, mother and two children. Spectral power (microV2) and mean frequency (Hz) measures from the delta, theta, alpha-1, alpha-2, beta-1, and beta-2 bands were computed for each family member. Non-family controls were constructed from the real family data by randomly pairing non-related individuals with one another, and correlations between the analogous individuals were also computed. The correlations for spectral power between family groups were greater than those obtained from the non-families for theta, alpha, and beta band power. The correlations for mean frequency between family members were greater than those of the non-families for the delta, theta, and alpha bands, although these were not as robust as the spectral power findings. In general, few family membership effects were found for the eyes open/closed or electrode site conditions. The results support findings from twin studies that suggest EEG characteristics are determined at least in part by genetic factors.

Adolescent↗
PubMed1995

Cognitive and biological determinants of P300: an integrative review.

The P300 event-related brain potential (ERP) is thought to reflect neuroelectric activity related to cognitive processes such as attention allocation and activation of immediate memory. However, recent studies have provided evidence that the P300 also is influenced by biological processes such as fluctuations in the arousal state of subjects. The effects of natural (circadian, ultradian, seasonal, menstrual) and environmentally induced (exercise, fatigue, drugs) state variables on the P300 are reviewed. The findings suggest that these factors contribute to P300 measures and are discussed in terms of their theoretical and applied implications.

Brain↗
PubMed1995

P300 differences between sinistrals and dextrals.

The P3(00) event-related potential (ERP) was elicited in 20 left- and 20 normal right-handed young adult male subjects using a simple visual stimulus discrimination task. For left-compared to right-handed subjects, P3 amplitude was larger at anterior electrode sites for the target stimuli and larger overall for the novel visual stimuli; P3 latency was shorter for left-compared to right-handers for the target stimuli. The N1, P2, and N2 components demonstrated similar handedness effects. The relationships of ERP amplitude and handedness to anatomical variables and cognitive factors are discussed.

Adult↗
PubMed1995

Non-invasive trigeminal evoked potentials: normative aging data.

A mild electric shock applied to the lower lip was used to elicit reliable evoked potentials from the trigeminal nerve in 50 normal adults who ranged in age from 20 to 69 years. The waveforms were morphologically similar to those observed with invasive procedures. No substantial effects for subject age, side of stimulation, or recording electrode were obtained for any of the individual trigeminal evoked potential amplitudes or latencies. Female subjects tended to have somewhat larger amplitudes and shorter latencies than male subjects. The results suggest that non-invasive procedures produce reliable evoked potential measures of trigeminal nerve function for patients of all ages.

Adult↗
PubMed1995

P300 assessment of chronic fatigue syndrome.

The P3(00) event-related brain potential (ERP) was elicited with an auditory tone-discrimination paradigm in 25 patients diagnosed with chronic fatigue syndrome (CFS) and 25 matched normal control subjects. Target stimulus probability was varied systematically (0.20, 0.50, 0.80) in different task conditions. No differences between the CFS and control subjects were found for either P3 amplitude or latency. No group effects were observed for the N1, P2, and N2 components. Despite the attentional and immediate memory deficits reported in CFS, the P3 ERP from auditory stimuli does not reliably discriminate CFS from matched control subjects.

Acoustic Stimulation↗
PubMed1995

P300 hemispheric amplitude asymmetries from a visual oddball task.

The P3(00) event-related potential (ERP) was elicited in 80 normal, right-handed male subjects using a simple visual discrimination task, with electroencephalographic (EEG) activity recorded at 19 electrodes. P3 amplitude was larger over the right than over the left hemisphere electrode sites primarily at anteromedial locations (F3/4, C3/4) for target, novel, and standard stimuli. The N1, P2, and N2 components also demonstrated hemispheric asymmetries. The strongest P3 hemispheric asymmetries for all stimuli were observed at anterior locations, suggesting a frontal right hemisphere localization for initial stimulus processing, although target stimuli produced larger P3 amplitudes at parietal locations that did novel stimuli. The relationships of hemispheric asymmetries to anatomical variables, background EEG activity, and neurocognitive factors are discussed.

Adult↗
PubMed1994

Handedness and hemispheric differences for feature perturbations.

The influence of handedness on hemispheric differences for feature perturbations was assessed in left- and right-handed normal subjects, with equal numbers of each sex in each group. Stimulus displays consisting of five small squares arranged in a single row were presented tachistoscopically to the left or right of fixation, and the size of the squares was manipulated in different conditions. Subjects were instructed to state in which square a horizontal "tick" mark was located. The handedness of the subjects contributed to the pattern of hemispheric differences for tick mislocations resulting from feature perturbations in the toward-fovea direction. For left-handed subjects, fewer errors occurred when stimuli were presented to the left hemisphere; for right-handed subjects, fewer errors occurred when stimuli were presented to the right hemisphere. Increasing stimulus size tended to enhance the handedness and hemispheric feature perturbation effects. The data suggest that handedness contributes to hemispheric organization of featural extraction processes.

Adult↗
PubMed1994

P300 habituation from visual stimuli?

The P3(00) event-related brain potential (ERP) was elicited with visual stimuli using an oddball task in which the subject indicated with a finger tap response the occurrence of a target stimulus that occurred randomly on 20% of the trials and refrained from responding to a standard stimulus. A total of six trial blocks were collected, with an equal number of artifact-free epochs averaged for both stimulus types. P3 amplitude from the target stimuli did not decrease across trial blocks; P3 amplitude from the standard stimuli did decrease across trial blocks. P3 latency from both the target and standard stimuli increased across trial blocks. No changes in amplitude or latency independent of the P3 effects were obtained for the other ERP components with trial block. The results suggest that P3 components elicited by visual stimuli do not readily habituate for actively discriminated target stimuli. The theoretical implications are discussed in the context of previous findings.

Adult↗
PubMed1994

Comparison of auditory P300 habituation from active and passive conditions.

The P3(00) event-related brain potential (ERP) was elicited using auditory stimuli and tasks in which the subject discriminated between standard and target tones or with passive task conditions in which the subject did not respond to either the standard or target stimuli. All stimulus presentations consisted of a series of ten-tone sequences in which the first six tones were always the standard and one of the last four tones was the target. The passive tasks were presented twice to assess for habituation effects. P3 amplitude was largest for the oddball task compared to the passive tasks, and repetition of the passive paradigm demonstrated a decrease in amplitude between conditions. P3 amplitude did not decrease across trials within any of the separate response conditions. P3 latency was shorter for the active discrimination relative to the passive tasks. The results suggest that the P3 component can be obtained reliably with passive procedures and does not habituate within a trial block. However, repeated blocks of passive stimulus presentations will cause the P3 ERP to diminish in size.

Acoustic Stimulation↗
PubMed1994

P300 from an auditory oddball task: inter-laboratory consistency.

Event-related potentials (ERPs) were recorded from normal subjects for the purpose of evaluating measurement consistency among six laboratories located in different cities within the United States. At each laboratory location 15 male subjects were tested using a simple auditory stimulus discrimination task and identical electrophysiological equipment and recording methods. Assessment of the N1, P2, N2, and P3(00) potentials from both the target and standard stimuli resulted in no reliable differences among laboratories for component amplitudes, latencies, and scalp distributions. Quantitative evaluation of overall waveform and specific component morphology yielded good to excellent agreement across laboratories. The findings suggest that large-scale inter-laboratory human electrophysiological studies are feasible and may prove of value when using ERPs to evaluate cognitive function in humans.

Adult↗
PubMed1994

P300 from a single auditory stimulus.

The P3(00) event-related brain potential (ERP) was elicited with auditory stimuli to compare 2 different discrimination tasks. The oddball paradigm presented both target and standard tones; the single-stimulus paradigm presented a target but no standard tone stimulus. Experiment 1 manipulated target stimulus probability (0.20, 0.50, 0.80) and produced highly similar P3 amplitude and latency results across probability levels for each paradigm. Experiment 2 factorially varied inter-stimulus interval (2 sec, 6 sec) and target stimulus probability (0.20, 0.80). P3 amplitude and latency were highly similar for both the oddball and single-stimulus procedures across all conditions.

Acoustic Stimulation↗
PubMed1994

P300 from families.

The P3(00) event-related brain potential (ERP) was elicited using auditory and visual stimuli in an oddball paradigm in 10 families, each consisting of a biologically related father, mother, and 2 children. P3 amplitude and latency measures from both stimulus modalities were more highly correlated between family members than between non-family individuals. Similar effects were found for the N1, P2 and N2 components. The results support findings from twin studies suggesting that genetic factors contribute to P3 morphological characteristics.

Acoustic Stimulation↗
PubMed1994

On the relationship between background EEG and the P300 event-related potential.

Background EEG was recorded from 24 subjects under eyes open/closed conditions for 5 min. The P3(00) event-related brain potential (ERP) was elicited with auditory stimuli when eyes were open/closed in the same subjects. Target stimulus probability was manipulated (0.20, 0.40, 0.60, 0.80) in different blocks under each eyes open/closed condition. Spectral analysis indicated that EEG power between 8 and 12 Hz demonstrated a similar scalp distribution as the P3 component of the ERP for the electrode sites employed. Spectral power and mean frequency were modestly correlated with P3 amplitude and peak latency primarily in the slower EEG bands, with associations observed across probability conditions and often strongest when target stimulus probability was .20. The results suggest that differences between individuals for EEG variation may contribute to P3 component variability, especially at the parietal recording site and under low target stimulus probability conditions when the P3 is largest and most stable.

Adolescent↗
PubMed1994

P300 is unaffected by glucose increase.

The effects of glucose ingestion on the P3(00) event-related brain potential (ERP) were investigated by using a visual stimulus oddball paradigm in which subjects discriminated between checkerboard (target) and horizontal line (standard) stimuli. Subjects were assessed for six consecutive trial blocks that were spaced 20 min apart on two different occasions. For the glucose condition, an initial baseline trial block was recorded followed by ingestion of 100 mg of glucose and the remaining five trial blocks recorded. For the water condition, the same procedure was employed with water ingested instead of glucose. Blood glucose levels, heart rate, and body temperature measures also were obtained before each trial block. P3 amplitude and latency did not change across trial blocks for the glucose/water conditions. No glucose/water effects were observed for the N1, P2, or N2 components as well. Blood glucose levels and heart rate increased for the glucose but not the water condition; body temperature decreased with the ingestion of both glucose and water and then returned to baseline levels. These findings suggest that ERPs are not influenced by increases of blood glucose level and are discussed in the context of previous ERP studies employing glucose manipulations.

Adult↗