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Biomedical subjects

A Pierson

Publications and source records attributed to A Pierson.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Changes in various activation indices as a function of the value given by a stimulus in anhedonic and deprossogenic subjects].

The aim of this experiment was to investigate, in "normal" subjects, the relationship between personality characteristics (anhedonia and depressogenic attitudes) and various tonic and phasic activation indices (EEG power spectra, CNV (at Fz and Cz), heart rate and reaction time) recorded during auditory stimulations, and the influence of the affective value of stimuli on phasic activation indices. Eighteen subjects were divided into two opposite groups according to their scores on two self-rating questionnaires (the Chapman Physical Anhedonia Scale and the Beck-Weissman Dysfunctional Attitude Scale): the A group (anhedonic with depressogenic attitudes) and the H group (hedonic and non-depressogenic). The experiment was divided into three phases. The first and third phase utilised an identical classical CNV paradigm. During the second phase, two of the three neutral warning tones of the first phase were given, by conditioning, a positive or a negative value. The results showed that: 1) before conditioning, when all stimuli were neutral, all activation indices (tonic and phasic) were significantly higher in the A group than in the H group; 2) after conditioning, the two groups differed mainly by their cortical reactivity to the positively conditioned sound: the amplitude of the two CNV components increased in the H group whereas a tendency to a CNV decrease was seen in the A group; 3) all the between-group CNV differences were significant only at Fz. These results were discussed in terms of differences of optimal level of activation.

Acoustic Stimulation↗
PubMed1987

Electrophysiological changes elicited by auditory stimuli given a positive or negative value: a study comparing anhedonic with hedonic subjects.

The present experiment investigates in 'normal' subjects the relationship between personality characteristics (anhedonia versus hedonia) and the influence of the affective value of acoustic stimuli (positive, negative, neutral) on various electrophysiological indices reflecting either tonic activation or phasic arousal (EEG power spectra, contingent negative variation: CNV, heart rate, skin potential responses: SPR) as well as on behavioural indices (reaction time: RT). Eighteen subjects were divided into two groups according to their scores at two self-rating questionnaires, the Chapman's Physical Anhedonia Scale (PAS) and the Beck-Weissman's Dysfunctional Attitude Scale (DAS) that quantifies cognitive distortions presumed to constitute high risk for depression: 9 with high scores at both scales formed the A group (Anhedonic-dysfunctional), 9 with low scores at both scales, the H group (Hedonic-adapted) The electrophysiological indices were recorded during 3 situations: the first one was a classical CNV paradigm with a motor reaction time task in which one of 3 tones of different pitch represented the warning stimulus S1; during the second, conditioning phase, two of these tones were associated with either a success (and reward) or a failure (and punishment) during a memory task in order to make them acquire either a positive or a negative affective value; the third situation consisted in the repeating of the first CNV paradigm in order to test the effect of the positive and the negative stimuli versus the neutral one on RTs and electrophysiological data. Significant between-group differences were found regarding tonic activation as well as phasic arousal indices from the very beginning of the experiment when all stimuli were neutral ones, the anhedonics exhibiting higher activation and arousal than the hedonics at the cortical (increased CNV amplitude, increased power in the beta frequency band), cardiovascular (higher heart rate habituating more slowly) and behavioural (faster RTs) levels. Significant between-group differences were also found concerning reactivity to affective stimuli during the third situation: both the orienting response (but only at the cortical level: early CNV) and the motor preparation processes (late CNV) were in the A group significantly less reactive to affective stimuli (especially to the positive one) than in the H group, in particular concerning the frontal (Fz) data.

Adult↗
PubMed1984

Protein-enhanced fluorescein chemiluminescence used in an immunoassay for rubella antibody in serum.

The chemiluminescence of fluorescein derivatives is greatly enhanced when they are conjugated to proteins. We exploited this property in devising a chemiluminescence immunoassay for rubella antibodies. In this sequential "sandwich"-type assay, tubes coated with rubella antigen are used for antibody separation and goat antibody to human IgG conjugated with fluorescein isothiocyanate is used for detection of bound rubella antibodies.

Antibodies, Viral↗
PubMed1984

[Familial Degos' atrophic papulosis (mother-daughter)].

Degos' disease (malignant atrophic papulosis) occurring in mother and daughter is described. Mother's eruption is composed of multiple characteristic lesions (up to 600). She does not have any gastrointestinal, neurological nor other visceral manifestations after a 9-year course. One year after the onset of the disease, she had a daughter. The pregnancy was normal and the newborn did not have any cutaneous manifestation. The daughter's first skin lesion appeared when she was 3-months old. She has now been under observation for nearly nine years and developed only four skin lesions without any visceral manifestation. Laboratory investigations show an increase in fibrinogen in both mother and child, without any sign of disseminated intravascular coagulation. The research for "slow virus" by a primate's intravascular inoculation of mother's skin lesion in negative.

Adult↗
PubMed1980

Relations between cochlear fatigue and the asymmetrical nonlinearity of the cochlear microphonics.

It is generally assumed that noises have a detrimental effect when the cochlear receptor is overloaded and, more specifically, when the cochlear microphonic (CM) fails to increase linearly with intensity. In order to investigate further the relations between the nonlinearity of CM and damage to the cochlea, a series of experiments was carried out on guinea pigs to relate the short-term CM depression following the presentation of noises or tones with the nonlinearity and the assymmetry. The asymmetrical non-linearity of CM was measured in tracing the input-out functions and also the wave-forms. Two other important tests of the asymmetrical nonlinearity were used: the measure of interference and of summating potential (SP DIF). The results show that the fatigability is greater when there is a large negative asymmetry or a large negative SP. Variations in asymmetry and in SP were observed among individuals. Other changes of symmetry were provoked by asphyxia or by introducing solutions of KCl in the perilymph. These changes were well correlated with the fatigability. These results are interpreted in a model of the cochlear transducer derived from the model of Davis. The assymetry of a flux of potassium ions between endolymph and the hair cells is assumed to be responsible for the alterations associated with cochlear fatigue and trauma.

Acoustic Stimulation↗
PubMed1979

[Relationship between cochlear fatigue and the asymmetrical non-linearity of microphonic responses in the guinea pig (author's transl)].

It is classically considered that cochlear fatigue and acoustic trauma occur when intensity is such that the ear is saturated, i.e. when the microphonic potential fails to increase in a linear fashion in relation to intensity and when distorsion appears. The present report concerns a study in the guinea pig of the relationship between the non-linearity of microphonic responses, and their fatigability. The results show that fatigability is related not only to non-linearity but also to the asymmetry of responses. The asymmetry of microphonic responses may be interpreted as reflecting an asymmetrical ionic flow at the upper pole of hair cells, resulting in an accumulation of potassium ions within and around hair cells and thereby creating a depression of responses.

Animals↗
PubMedDate not supplied

Anhedonia and blunted affect in major depressive disorder.

The relation between anhedonia and affective flattening was studied in 61 normal subjects and 61 major depressives. Affective flattening and anhedonia were defined by the following self-rating scales: Fawcett-Clark Pleasure Capacity Scale (FCPCS), Hardy Displeasure Capacity Scale (HDCS), FCPCS-PP (subscale of physical pleasure), and HDCS-PD (subscale of physical displeasure). The depressives are more sensitive to displeasure and more anhedonic than controls. Concerning physical stimulations (FCPCS-PP and HDCS-PD) in the depressed group, anhedonia and affective flattening are not linked, suggesting that physical anhedonia is not secondary to low emotional reactivity (affective flattening) and constitutes an independent dimension.

Adult↗
PubMedDate not supplied

Increased fatigue of cochlear potentials after injection of KCl solution in the perilymph.

Cochlear microphonics (CM), action potentials (AP) and endochochlear potential (EP) were recorded on guinea pigs. The introduction of a small quantity of KCl solution (0.1 N) in the perilymph provoked a moderate decrease of CM and AP. During the period of depressed but stable amplitude, the presentation of intense sounds provoked an exaggerated susceptibility to fatigue and a delayed recovery. Similar changes were observed in the evolution of EP. However, the recovery was slower for EP than for CM. The results, as a whole, suggest that the fatigue which is manifested in the depression of cochlear potentials is related to a leakage of potassium ions from endolymph to fluids spaces within the organ of Corti.

Acoustic Stimulation↗
PubMedDate not supplied

[Study of cognitive evoked potentials as a function of the affective value and significance of stimuli in anhedonic healthy subjects with dysfunctional attitudes].

In depression studies, it is important to consider healthy subjects with characteristics which may be predictive of depression. Such are anhedonia and some "dysfunctional" attitudes. For this reason, subjects with or without these characteristics were submitted to an experimental paradigm allowing an analysis of their electroencephalographical (CNV and P300) reactivity according to affective value and meaning of stimuli, and according to the probability of occurrence of these stimuli. Subjects were divided into two groups according to their scores on two scales: the Physical Anhedonia Scale of Chapman et al. and the Dysfunctional Attitudes Scale of Weissman and Beck. Several results enabled to differentiate the two groups. Anhedonic and depressogenic subjects were characterized mainly by a particular type of processing for failure situations and for the stimulus which were associated with those situations.

Acoustic Stimulation↗
PubMedDate not supplied

[Automatic information processing, the frontal system and blunted affect. From clinical dimensions to cognitive processes toward a psychobiological explanation of temperament].

Several theorists have drawn a distinction between automatic and attentional or controlled processing. Hasher and Zacks (1979), were the very first to argue that effortful processes are reduced under conditions of stress including depression. They suggested that, in these conditions, no such deficit occurs in automatic processing. Then, Weingartner and co-workers provided some experiments which seemed to support such an interpretation of the cognitive dysfunction in depressed patients. However, some recent data do not fit with this well admitted theoretical framework. The purpose of our article is to try to clarify this issue both from a theoretical and from a methodological point of view. First, we make a critical review of the most recent results in three fields of experimentation related to the "automatic versus controlled" topic: 1) The classical neuropsychology of memory which manipulates the level of effort required to perform the tasks. Confusion arises when theories at the process level are tested with reference to data collected at the task level. The transparency assumption could be false: Impairment in an effort-demanding task could be due to a defect in automatic processes and it is possible to hypothesize that the more automatic processes are deficient, the more controlled processes are saturated and the effort demanding task impaired. The emergence of controlled processes could depend on the level of automaticity and the regulation of automatic processes could be determinant for the ability of the subject to make associations. 2) The recent studies on implicit memory in depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗