Search PubMed⌕ Search

Biomedical subjects

J Polich

Publications and source records attributed to J Polich.

At least 127 records · Page 7Linked to original sources
PubMed1987

Response mode and P300 from auditory stimuli.

The P300 component of the event-related brain potential (ERP) was elicited with a simple auditory discrimination task. Subjects were required to respond in three different ways to target stimuli across conditions: (1) silently counting the targets; (2) tapping their index finger every time a target was detected; or (3) pressing a button with their thumb when a target was presented. In addition, ERPs were recorded during each response mode while the subjects' eyes were either open or closed. P300 amplitude was larger for the counting compared to the tapping or button press tasks especially during the eyes closed condition. The peak latency of the P300 was longer when obtained from the counting compared to the tapping and button-press tasks for both eye conditions. Response mode also interacted with electrode site for peak latency. The results suggest that the P300 ERP component is sensitive to the nature of the subject's response during discrimination tasks.

Adult↗
PubMed1986

P300 latency reflects the degree of cognitive decline in dementing illness.

An auditory discrimination paradigm was employed to elicit the P3 component of the event-related brain potential (ERP) from 39 demented patients (mean age = 71 years). Component latency was longer in patients who were diagnosed as having primary degenerative dementia and other cognitive impairment disorders compared to age-matched controls. Neurologist ratings of cognitive impairment were significantly correlated with P3 latency values, although no differences in mean latency were obtained between the various categories of dementia. ERP measurement techniques and the interpretation of P3 latency as in index of dementing illness are discussed.

Aged↗
PubMed1986

Attention, probability, and task demands as determinants of P300 latency from auditory stimuli.

A series of 3 experiments investigated factors which could affect the morphological quality and latency of the P3 ERP component from auditory stimuli. Manipulations of attention and probability of the target tone changed P3 amplitude but typically demonstrated little effect on P3 latency. No differences for either component measure were obtained when recordings were made with the subjects' eyes open or closed. Passively ignoring the stimulus items decreased P3 amplitude and increased its latency relative to active stimulus discrimination.

Acoustic Stimulation↗
PubMed1986

Hemispheric differences for feature detection.

The role of hemispheric processing for visual features was explored by tachistoscopically presenting subjects with stimulus displays composed of the letter I, displays in which a single T was embedded in an array of I's, or displays in which the letter O was embedded in an array of I's. The number of array elements was also manipulated (4, 16, or 36) to assess the effects of display size on featural detection for each visual field. Subjects verbally indicated whether array elements were all the same, or whether a T or O was present. Hemispheric error rates varied as a function of the type of letter to be detected, with left-hemisphere presentations producing superior performance for the detection of T's, right-hemisphere presentations yielding superior performance for the detection of O's, and Same displays demonstrating hemispheric patterns consistent with these results. The findings suggest that the analysis of perceptual features during visual stimulus processing may determine hemispheric outcomes in a variety of task situations.

Dominance, Cerebral↗
PubMed1986

Normal variation of P300 from auditory stimuli.

The P300 (P3) event-related potential was obtained from 100 undergraduates with a 2-tone auditory discrimination task (20% targets) and replicated trial block procedure. Normal variation for P3 amplitude and latency was assessed with frequency distributions and descriptive statistics for the midline electrode placements. P3 latency and amplitude were negatively correlated, most strongly at the Pz electrode site. No significant effects between trial block replications, subject gender, or reported alcohol consumption on either amplitude or latency were found.

Acoustic Stimulation↗
PubMed1986

P300 and alcohol consumption in normals and individuals at risk for alcoholism. A preliminary report.

Pairs of college student subjects (36 male, 36 female) were matched on age, sex, and personal drinking history. One pair member had a parent who met the DSM III criteria of alcoholism, while the other pair member had no close alcoholic relative. The P300 event-related brain potential (ERP) was obtained from each subject with auditory stimuli in an "oddball" paradigm. Target stimuli occurred randomly on 20% of the trials in a frequency discrimination task, a relatively easy intensity discrimination task, and a more difficult intensity discrimination task. Subjects indicated when the target items occurred by moving their index finger. No significant overall effects were obtained for family history for either P300 latency or amplitude. P300 latency increased and amplitude decreased with increases in the reported amount of alcohol consumption in all subjects only for the difficult intensity task but were statistically significant only for individuals with a negative family history for alcoholism.

Adolescent↗
PubMed1985

Semantic categorization and event-related potentials.

The N400 component of the event-related brain potential (ERP) was examined by presenting subjects with a series of words belonging to the same category and a series of declarative sentences. Half of the word series ended with a semantically unrelated word, while half of the sentences ended with a semantically inappropriate word. In the first experiment, subjects were instructed to read the word series and sentences, while in the second experiment they were instructed to indicate whether the word series or sentences ended appropriately or not with a button-press response. Word series and sentences with semantically incongruous endings produced a robust negative component at 400 msec followed by a positive-going wave for both the reading and decision tasks. When the subjects were required to categorize the word series and sentences endings, the negative component was followed by a robust P3 in both conditions. Analysis of scalp amplitude distributions for each task taken in conjunction with previous findings suggests that the semantically induced N400 component is most likely a "generic" N2. The relationship between the N2, N400, and P3 is discussed.

Adult↗
PubMed1985

Stimulus frequency and masking as determinants of P300 latency in event-related potentials from auditory stimuli.

The effects of target tone frequency, presence of a masking stimulus, and subject sex on the auditory ERP were studied with an 'oddball' paradigm. P300 latency became shorter (about 15 msec) as the difference between the standard (1000 Hz) and target tone frequency increased (1500, 2000, 4000 Hz) but became longer (about 10 msec) with the presence of a white noise masking stimulus. Similar results were obtained for both the P3a and P3b subcomponents of the P300 potential. No significant differences between the adult male and female subjects were observed. The role of stimulus parameters in applied testing situations is discussed.

Acoustic Stimulation↗
PubMed1985

Effects of age on the P300 component of the event-related potential from auditory stimuli: peak definition, variation, and measurement.

An auditory "oddball" paradigm was used to elicit the P300 component of the event-related brain potential (ERP) from a large sample of young (5 to 15 years) and older (20 to 86 years) persons. Distinct P3a and P3b subcomponents of the P300 were observed within individuals and across trial blocks. Age affected P300 latency in a similar fashion for both subcomponents with latency increasing about 65 msec between 20 and 70 years. P300 latency variability also was found to increase somewhat with advanced age. These results confirmed previous age-related ERP changes and extended them to the P3a and P3b subcomponents.

Acoustic Stimulation↗
PubMed1984

Hemispheric patterns in visual search.

A visual search paradigm was employed to examine hemispheric serial and parallel processing. Stimulus arrays containing 4, 9, or 16 elements were tachistoscopically presented to the right visual field-left hemisphere (RVF-LH) or left visual field-right hemisphere (LVF-RH). Subjects judged whether all of the elements within an array were physically the same (all X's) or whether one (O) was different from the rest. Left hemisphere presentations were processed more quickly and accurately than LVF-RH presentations for all stimulus conditions. As the number of array elements increased, more errors and longer response times were obtained for different stimulus items whereas fewer errors and somewhat shorter response times were obtained for same stimulus items. These and previous results suggest that the left hemisphere obtains an advantage for visual search because of that hemisphere's superiority for fine-grained feature analysis rather than because of a fundamental hemispheric serial/parallel processing dichotomy.

Attention↗
PubMedDate not supplied

Hemispheric differences for P300 amplitude from an auditory oddball task.

The P3(00) event-related potential (ERP) was elicited in 80 normal, right-handed male subjects using a simple auditory stimulus discrimination task, with electroencephalographic (EEG) activity recorded at 19 electrodes. P300 amplitude was larger over the right compared to left hemisphere electrode sites primarily at anterior-medial locations (F3/4, C3/4) for both target and standard stimuli. The N100, P200, and N200 components also demonstrated several similar, albeit less robust, hemispheric asymmetries. No hemispheric effects for P300 latency were observed, with few consistent latency findings for any of the other components obtained. The results suggest that the discrimination process underlying P300 generation may originate with right frontal activation.

Acoustic Stimulation↗