Marien Gadea

Dichotic Listening and Corpus Callosum Magnetic Resonance Imaging in Relapsing-Remitting Multiple Sclerosis With Emphasis on Sex Differences

Twenty-five early-onset relapsing-remitting multiple sclerosis patients (12 women and 13 men) with mild disability were compared with 25 matched controls in a dichotic listening (DL) test under nonforced and forced attentional-shift conditions. Patients showed left ear impairment and no left ear advantage in the forced-left condition. Four corpus callosum (CC) regions were measured in patients on a midsaggital magnetic resonance imaging scan. The right ear score was negatively correlated whereas the left ear score was positively correlated with CC regions (significant only for the nonforced condition). Moreover, in men, the correlations with DL scores were linked mainly to the splenium and posterior isthmus, and in women, they were stronger for anterior isthmus and posterior body. An inverse correlation between months of disease evolution and CC area was found only in women.

Increased cortisol and decreased right ear advantage (REA) in dichotic listening following a negative mood induction.

This study aimed to evaluate neuroendocrine responses and changes in perceptual asymmetry following an induced negative affect. Cortisol increasing in response to negative affect has been reported, while current brain models of emotion processing link negative affect to the right hemisphere. In this study, the Velten Mood Induction Procedure was used to generate neutral or negative affect in 44 healthy subjects. The PANAS scales were used to assess self-reported mood. A consonant-vowel dichotic listening (DL) test was applied after the neutral and negative affect inductions, and levels of salivary cortisol were determined by radioimmunoassay. For the negative affect condition, and congruent with the hypothesis tested, PANAS positive scores diminished (p<0.001) and PANAS negative scores increased (p<0.001), yielding an inverse correlation between them. A significant increase in cortisol levels was also seen (p<0.04). When taking cortisol reactivity into account, PANAS negative scores were higher for high-than for low-cortisol responders (p<0.02). Regarding DL, an increase in left ear items (p<0.04) and a decrease in right ear items (p<0.03) reported for those subjects who obtained a right ear advantage in the neutral condition. An explanation in terms of Kinsbournes model for attentional-activation influences on DL is postulated and implications for the issue of affective illness are also discussed.

Salivary testosterone is related to both handedness and degree of linguistic lateralization in normal women

The aim of this study was to test the hypothesis that individual differences in testosterone (T) are associated with different patterns of linguistic lateralization and hand preference. Twenty left-handed (LH) and 19 right-handed (RH) women filled in a handedness questionnaire and performed a consonant-vowel dichotic listening test (DL-CV). Salivary T was measured by radioimmunoassay (RIA). LH women showed significantly lower mean salivary T than RH women. T levels were negatively correlated with the absolute value of the DL laterality index. Subjects with right ear advantage (REA) were classified into strongly and weakly lateralized following Wexler et al. method (Brain Lang. 13 (1981) 13). When taking into account hand preference, a pattern emerged in that RH-strongly lateralized and LH-weakly lateralized women showed similar T levels. The lowest level appeared for LH-strongly lateralized women and the highest for RH-weakly lateralized women, being significantly different from each other. The results are discussed in terms of several theories that have proposed a link between testosterone and cerebral lateralization.

What happens when we get angry? Hormonal, cardiovascular and asymmetrical brain responses

This study aimed to evaluate neuroendocrine and cardiovascular responses together with changes in brain asymmetry following an anger mood induction laboratory task. Previous research has shown an increase in heart rate and blood pressure when anger is experienced. Increased testosterone and decreased cortisol in response to anger and aggressive behavior have also been reported. With regard to asymmetrical frontal brain activity and emotion, the valence model links negative affect (as anger) to the right hemisphere while the motivational direction model links approach-related emotions (as anger) to the left hemisphere. From the subjective perception and from the neuroendocrine and cardiovascular response of the subjects, we can conclude that the self-referent statement anger induction method by Engebretson et al. (1999) was able to generate an experience of an anger affect in 30 healthy men. Another question was to analyze the consequences of that experience upon perceptual asymmetry when measured with a non-emotional laterality task. Regarding dichotic listening, an enhanced REA (right ear advantage) was observed after anger which indicates greater left hemisphere activity, supporting the motivational direction model.

Test-retest performance for the consonant-vowel dichotic listening test with and without attentional manipulations

The present work aimed to replicate Hugdahl and Hammars (1997) study on the reliability of dichotic listening under divided or focused attention conditions. With the same consonant-vowel syllable dichotic listening procedure, 16 subjects were tested twice, 2 weeks apart. The design included a condition without attentional instructions (nonforced) and two conditions with the instruction to attend either to the right- or the left-ear input. The results showed a significant correlation coefficient of .82 for the standard nonforced condition, indicating temporal stability for the ear advantages. There were also high correlation coefficients for the focused attention conditions (.77 and .76), although the subjects performed the attentional instructions more accurately in session two.

The sad, the angry, and the asymmetrical brain: Dichotic Listening studies of negative affect and depression

Dichotic Listening (DL) is a valuable tool to study emotional brain lateralization. Regarding the perception of sadness and anger through affective prosody, the main finding has been a left ear advantage (LEA) for the sad but contradictory data for the anger prosody. Regarding an induced mood in the laboratory, its consequences upon DL were a diminished right ear advantage (REA) for the induction of sadness and an increased REA for the induction of anger. The global results fit with the approach-withdrawal motivational model of emotional processing, pointing to sadness as a right hemisphere emotion but anger processed bilaterally or even in the left hemisphere, depending on the subjects preferred mode of expression. On the other hand, the study of DL in clinically depressed patients found an abnormally larger REA in verbal DL tasks which was predictive of therapeutic pharmacological response. However, the mobilization of the available left hemisphere resources in these responders (reflected in a higher REA) would indicate a remission of the episode but would not assure the absence of new relapses.

Corpus callosum function in verbal dichotic listening: Inferences from a longitudinal follow-up of Relapsing-Remitting Multiple Sclerosis patients

This study conducted a follow-up of 13 early-onset slightly disabled Relapsing-Remitting Multiple Sclerosis (RRMS) patients within an year, evaluating both CC area measurements in a midsagittal Magnetic Resonance (MR) image, and Dichotic Listening (DL) testing with stop consonant vowel (C-V) syllables. Patients showed a significant progressive loss of posterior CC areas (isthmus and splenium) related to increasing EDSS scores and an enhancing right ear advantage (REA) over time. A significant correlation between posterior CC areas and DL scores emerged in both evaluations, being negative for the right and positive for the left ear. The pattern of correlations suggests that the CC can serve an inhibitory and also excitatory influence on the contralateral hemisphere when studying the phonological processing of language. STATEMENT OF SIGNIFICANCE TO THE NEUROSCIENCE OF LANGUAGE: The scope of the manuscript is language lateralization. The task used in the experiment is a verbal dichotic listening task, tapping the most basic phonological aspects of language. Finally, the available research is scarce when focusing on the interhemispheric excitation or inhibition of the corpus callosum in linguistic functioning.

Abnormal synchrony and effective connectivity in patients with schizophrenia and auditory hallucinations.

Auditory hallucinations (AH) are the most frequent positive symptoms in patients with schizophrenia. Hallucinations have been related to emotional processing disturbances, altered functional connectivity and effective connectivity deficits. Previously, we observed that, compared to healthy controls, the limbic network responses of patients with auditory hallucinations differed when the subjects were listening to emotionally charged words. We aimed to compare the synchrony patterns and effective connectivity of task-related networks between schizophrenia patients with and without AH and healthy controls. Schizophrenia patients with AH (n = 27) and without AH (n = 14) were compared with healthy participants (n = 31). We examined functional connectivity by analyzing correlations and cross-correlations among previously detected independent component analysis time courses. Granger causality was used to infer the information flow direction in the brain regions. The results demonstrate that the patterns of cortico-cortical functional synchrony differentiated the patients with AH from the patients without AH and from the healthy participants. Additionally, Granger-causal relationships between the networks clearly differentiated the groups. In the patients with AH, the principal causal source was an occipital–cerebellar component, versus a temporal component in the patients without AH and the healthy controls. These data indicate that an anomalous process of neural connectivity exists when patients with AH process emotional auditory stimuli. Additionally, a central role is suggested for the cerebellum in processing emotional stimuli in patients with persistent AH.

A comparison of the effects for sustained versus shifted attention on dichotic listening performance.

We measured the effect of two types of directed attention instructions, sustained by a verbal cue or shifted by a tone cue with different time intervals (150, 450, and 750 ms), on a consonant-vowel dichotic listening (C-V DL) test for a large group of right- and left-handed participants of both sexes. An increasing of the hits and a decreasing of the intrusions from the baseline DL test scores was evident for both types of attentional manipulations, with no differences regarding sex or handedness. Increasing the time from 150 to 450 ms benefited the focusing of attention but this advantage was markedly attenuated at the longer 750-ms interval. The improving effect was seen for the hits of both the left and right ears and so a right ear advantage was evident for the three time intervals.

Deceit and facial expression in children: the enabling role of the "poker face" child and the dependent personality of the detector.

This study presents the relation between the facial expression of a group of children when they told a lie and the accuracy in detecting the lie by a sample of adults. To evaluate the intensity and type of emotional content of the children’s faces, we applied an automated method capable of analyzing the facial information from the video recordings (FaceReader 5.0 software). The program classified videos as showing a neutral facial expression or an emotional one. There was a significant higher mean of hits for the emotional than for the neutral videos, and a significant negative correlation between the intensity of the neutral expression and the number of hits from the detectors. The lies expressed with emotional facial expression were more easily recognized by adults than the lies expressed with a “poker face”; thus, the less expressive the child the harder it was to guess. The accuracy of the lie detectors was then correlated with their subclinical traits of personality disorders, to find that participants scoring higher in the dependent personality were significantly better lie detectors. A non-significant tendency for women to discriminate better was also found, whereas men tended to be more suspicious than women when judging the children’s veracity. This study is the first to automatically decode the facial information of the lying child and relate these results with personality characteristics of the lie detectors in the context of deceptive behavior research. Implications for forensic psychology were suggested: to explore whether the induction of an emotion in a child during an interview could be useful to evaluate the testimony during legal trials.