Does the heart know what the ears hear? A heart rate analysis of auditory selective attention

Increased cardiac vagal tone in childhood-only, adolescent-only, and persistently antisocial teenagers: the mediating role of low heart rate

BACKGROUND

Cardiac vagal tone is an indicator of parasympathetic nervous system functioning, and there is increasing interest in its relation to antisocial behavior. It is unclear however whether antisocial individuals are characterized by increased or decreased vagal tone, and whether increased vagal tone is the source of the low heart rate frequently reported in antisocial populations.

METHODS

Participants consisted of four groups of community-dwelling adolescent boys aged 15.7 years: (1) controls, (2) childhood-only antisocial, (3) adolescent-only antisocial, and (4) persistently antisocial. Heart rate and vagal tone were assessed in three different conditions: rest, cognitive stressor, and social stressor.

RESULTS

All three antisocial groups had both lower resting heart rates and increased vagal tone compared to the low antisocial controls across all three conditions. Low heart rate partially mediated the relationship between vagal tone and antisocial behavior.

CONCLUSIONS

Results indicate that increased vagal tone and reduced heart rate are relatively broad risk factors for different developmental forms of antisocial behavior. Findings are the first to implicate vagal tone as an explanatory factor in understanding heart rate - antisocial behavior relationships. Future experimental work using non-invasive vagus nerve stimulation or heart rate variability biofeedback is needed to more systematically evaluate this conclusion.

Cardiac Response During Auditory Selective Attention to Tones and Affective Sounds

We conducted an experiment to determine if attention to affective sounds showed a lateral bias. Twenty-two participants were instructed to respond to one of two pure tones presented monaurally and to a set of pleasant and unpleasant sounds from the International Affective Digitized Sounds set. Participants were instructed to respond to pleasant or unpleasant sounds in the right or left ear, attending to pleasant/right, pleasant/left, unpleasant/right, and unpleasant/left sounds in separate blocks. Evoked cardiac response to the tones showed significant cardiac deceleration in response to attended sounds in the attended ear. In addition, pleasant sounds elicited significant cardiac deceleration when attended in the right ear, but not in the left. Unpleasant sounds elicited significant cardiac deceleration when attended in both ears. Consistent with the anterior valence hypothesis, our data suggests that pleasant sounds are mainly processed in the left hemisphere, but in contrast to this hypothesis, unpleasant sounds are processed bilaterally.

Subjective and psychophysiological indexes of listening effort in a competing-talker task

BACKGROUND

The effects of noise and other competing backgrounds on speech recognition performance are well documented. There is less information, however, on listening effort and stress experienced by listeners during a speech-recognition task that requires inhibition of competing sounds.

PURPOSE

The purpose was (a) to determine if psychophysiological indexes of listening effort were more sensitive than performance measures (percentage correct) obtained near ceiling level during a competing speech task, (b) to determine the relative sensitivity of four psychophysiological measures to changes in task demand, and (c) to determine the relationships between changes in psychophysiological measures and changes in subjective ratings of stress and workload.

RESEARCH DESIGN

A repeated-measures experimental design was used to examine changes in performance, psychophysiological measures, and subjective ratings in response to increasing task demand.

STUDY SAMPLE

Fifteen adults with normal hearing participated in the study. The mean age of the participants was 27 (range: 24-54).

DATA COLLECTION AND ANALYSIS

Psychophysiological recordings of heart rate, skin conductance, skin temperature, and electromyographic (EMG) activity were obtained during listening tasks of varying demand. Materials from the Dichotic Digits Test were used to modulate task demand. The three levels of task demand were single digits presented to one ear (low-demand reference condition), single digits presented simultaneously to both ears (medium demand), and a series of two digits presented simultaneously to both ears (high demand). Participants were asked to repeat all the digits they heard, while psychophysiological activity was recorded simultaneously. Subjective ratings of task load were obtained after each condition using the National Aeronautics and Space Administration Task Load Index questionnaire. Repeated-measures analyses of variance were completed for each measure using task demand and session as factors.

RESULTS

Mean performance was higher than 96% for all listening tasks. There was no significant change in performance across listening conditions for any listener. There was, however, a significant increase in mean skin conductance and EMG activity as task demand increased. Heart rate and skin temperature did not change significantly. There was no strong association between subjective and psychophysiological measures, but all participants with mean normalized effort ratings of greater than 4.5 (i.e., effort increased by a factor of at least 4.5) showed significant changes in skin conductance.

CONCLUSIONS

Even in the absence of substantial performance changes, listeners may experience changes in subjective and psychophysiological responses consistent with the activation of a stress response. Skin conductance appears to be the most promising measure for evaluating individual changes in psychophysiological responses during listening tasks.

Neuroticism-Anxiety, Impulsive-Sensation Seeking and autonomic responses to somatosensory stimuli

This study focused on autonomic responding in participants who scored high vs. low on the Neuroticism-Anxiety (N-Anx) and Impulsive-Sensation Seeking (Imp-SS) dimensions of the Zuckerman-Kuhlman Personality Questionnaire--Form III. Participants were presented with series of tones (standards, deviants and novels) and they received a mild electric shock (one, two or three pulses) at each 15th tone. Resting pre-stimulus skin conductance level (SCL) and heart rate (HR) level was recorded, as well as the skin conductance response (SCR) and (anticipatory) HR response to the electric stimuli. The autonomic measures differentiated between high- vs. low Imp-SS participants but failed to discriminate between high- vs. low N-Anx participants, with the exception that high N-Anx participants showed smaller SCRs on some trials compared to the low N-Anx participants. High Imp-SS had a lower pre-stimulus SCL and smaller SCRs to deviant stimuli compared to low Imp-SS participants. Additionally, their HR acceleration was smaller in anticipation of the first and the deviant tones whereas their deceleratory response was larger relative to the HR changes observed for the low Imp-SS participants. This pattern of findings was taken to suggest that high Imp-SS participants are more arousable and less prone to defensive reactions to novel or aversive stimulation.

Age and novelty: Event-related brain potentials and autonomic activity

Our aim was to study age-related differences in the habituation of orienting reaction by using novel visual stimuli. We intended to fill a gap in habituation research by recording both autonomic and ERP components of orienting to visual stimuli in the same sample and in highly related paradigms. We report data showing that in young subjects repetition of visual novels yielded fast habituation of both skin conductance responses and ERP components (P3(novel), N2b) whereas elderly people displayed no sign of habituation. However, cardiac deceleration--thought conventionally to be part of the orienting reaction--did not habituate in either group. Overall, most of our results harmonize with those obtained by using auditory stimuli; therefore we conclude that there is no significant modality specificity in age-related deterioration of habituation processes.

Physically abused children's regulation of attention in response to hostility

The present study examines the effects of early emotional experiences on children's regulation or strategic control of attention in the presence of interpersonal hostility. Abused children's reactions to the unfolding of a realistic interpersonal emotional situation were measured through multiple methods including autonomic nervous system changes and overt behavioral performance. Although physically abused and non-physically abused 4-year-old children did not differ in terms of their baseline levels of arousal, marked differences in physically abused children's regulatory responses to background anger emerged. These data suggest that the emergence of anger leads to increases in anticipatory monitoring of the environment among children with histories of abuse. Results are discussed in terms of risk factors in the development of psychopathology.

The cardiac cycle time effect revisited: temporal dynamics of the central-vagal modulation of heart rate in human reaction time tasks

Lacey and Lacey (1974) suggested that during reaction time tasks higher brain centers dynamically adjust efferent vagal nerve pulses to the sino-atrial node of the heart, inducing phase-dependent heart rate changes. Since then, animal and human neuro-physiological results have provided evidence for this hypothesis. Higher subcortical and cortical brain centers may have reciprocal interactive pathways relating to autonomic control comparable to those at the level of peripheral autonomic changes and brain stem reflexes. In humans such central effects may be observed in the short latency vagal control of heart rate that has been studied mostly in reaction time (RT) tasks. RT task parameters modulate vagal pulses to the cardiac sino-atrial node (SAN), which in turn exerts a phase-dependent change in the ongoing cardiac interbeat interval. Simulations of human RT task effects in an animal model of heart rate change support this hypothesis. The current study examined evidence for vagal control of three human phasic heart rate responses in RT tasks. The evidence indicates that the initiation of an RT response triggers a reflexive shift from vagal activation to vagal inhibition. This shift is cardiac cycle phase dependent. Graded anticipatory cardiac deceleration during the warning interval of an RT task varies with task relevance and time uncertainty. This response may be part of a control process engaged in time keeping. Hence, temporal variables mediate the central-autonomic-vagal modulation of heart rate.

Developmental changes in inhibitory processing: evidence from psychophysiological measures

Two major theories of the development of inhibitory functioning are discussed that assume a close relation between inhibitory ability and the maturation of the frontal lobes. It is argued that a psychophysiological approach may add considerably to the study of developmental change in inhibitory processes. A selective review is presented of studies examining heart rate and brain potential measures obtained in a variety of paradigms supposedly showing inhibitory control. The results of these studies are discussed within the framework proposed by Stuss et al. [Stuss, D.T., Shallice, T., Alexander, M.P., Picton, T.W., 1995. A multidisciplinary approach to anterior attentional processing. In: Grafman, J., Holyoak, K.J., Boller, F. (Eds.), Structure and functions of the human prefrontal cortex. Ann. New York Acad. Sci. 769, 191-211], relating component processes of supervisory-system control to distinct brain regions and psychophysiological measures of attention. It is concluded that the supervisory-system framework provides a heuristic way for examining developmental changes in inhibitory processing.

Attention and selection in the growing child: views derived from developmental psychophysiology

Our understanding of developmental changes in attentional selection in the growing child has been advanced substantially by the results of (a relatively small number of) studies undertaken from a psychophysiological perspective. The basic outcome of these studies is that, in attentional filtering as well as selective set (the two basic paradigms in attention research), the processes necessary for attentional selection are in essence available even to the young child; however, the speed and efficiency of these processes tends to increase as the child grows into an adolescent. Under optimal conditions, filtering is performed at early stages of information processing, but less optimal stimulus characteristics and task requirements may induce a shift in the locus of selection to later processing stages for young children whereas older individuals are better able to preserve their early locus of selection. When early selection is constrained, young children are substantially more sensitive to the adverse effects of response competition. In selective set, sub-optimal conditions lead not so much to a shift in locus of selection processes, but to a shift in the age at which asymptote efficiency is attained. We have proposed hierarchical regression analysis as a useful technique to examine whether age-related differences in attention effects, as observed in specific ERP components and in RT, are reflections of an age effect on a single source of attentional selection or of separate sources that each contribute uniquely to the developmental trends seen in (attention effects on) RT. Re-analyses of existing data demonstrated that (again depending on task specifics) many but not all of the different component processes involved in attentional selection contributed unique variance to the age-related changes in attention effects.

Musical rhythms in heart period dynamics: a cross-cultural and interdisciplinary approach to cardiac rhythms

The purpose of this study was to expand classic heart period analysis methods by techniques from ethnomusicology that explicitly take complex musical rhythm principles into consideration. The methods used are based on the theory of African music, the theory of symbolic dynamics, and combinatorial theory. Heart period tachograms from 192 24-h electrocardiograms of 96 healthy subjects were transformed into binary symbol sequences that were interpretable as elementary rhythmic (percussive) patterns, the time lines in African music. Using a hierarchical rhythm pattern scheme closely related to the Derler Rhythm Classification (from jazz theory), we calculated the predominance and stability of pattern classes. The results show that during sleep certain classes, specific to individuals, occurred in a cyclically recurrent manner and many times more often than expected. Simultaneously, other classes disappeared more or less completely. Moreover, the most frequent classes obviously originate from phase-locking processes in autonomic regulation (e.g., between respiratory and cardiac cycles). In conclusion, the new interdisciplinary method presented here demonstrates that heart period patterns, in particular those occurring during night sleep, can be interpreted as musical rhythms. This method may be of great potential use in music therapy research.