Dynamics of heart rate response in sleeping infants exposed to tone stimuli

Heart rate, EEG, and motor responses were recorded following presentation of a series of 6–10 sound stimuli (2.5-s tones of 1000, 4000, and 250 Hz, 70 dB, interstimulus intervals 18–25 s) in neonates aged 9 to 22 weeks during stage 2–3 sleep. The infants (17 of 19) revealed heart rate (HR) changes in response to tone stimuli that consisted in an expanded form of three phases: (1) short-latency (at 1 s after tone presentation) HR deceleration, (2) HR acceleration with a maximum at 3–5 s, and (3) late HR deceleration at 6–9 s of the poststimulus interval. The occurrence rate of the first two phases of cardiac response is relatively constant during a series of stimuli, whereas the likelihood of late HR deceleration is the highest following the first tone presentation and decreases significantly when the stimulus is repeated. Differences in the dynamics and statistical analysis allow a relative independence of all the three response phases to be suggested. The HR acceleration phase is dramatically enhanced in association with the motor response elicited by the sound stimulus. The late HR deceleration phase occurs not only after the first presentation of stimuli, but also when they are repeated if they evoke EEG reaction (vertex potentials) in response to both the beginning and end of the tone sound. Possible mechanisms of the three phases of poststimulus HR changes are: the vagal cardiac reflex associated with the acoustic (adaptive) reflex, activation of sympathetic efferents in combination with the startle reflex, and secondary vagal deceleration of sinus rhythm likely to be associated with the processes of perception (detection) of a “novel” stimulus and to serve as an indirect sign of an orienting reaction.     

Role of cognitive and personality variables in regulation of heart rhythm

The heart rate (HR) response to stimulation is described as a biphasic function with a phase of deceleration and acceleration. The deceleration is interpreted as a component of orienting behavior or of stimulus intake and acceleration as a sign of internal information processing going along with the rejection of external stimulation. However, there are many authors who do not support this assumption. The question arises whether the heart rate patterns are concomitant or even dependent on breathing behavior. Also the sensitivity of HR as an indicator of influence of selfregulatory processes on physiological functions remains still a problem for future studies. In general it may be concluded that the HR is one of the relatively independent indices of changes in the level of activation or mobilization. The HR in healthy subjects is a function not only of intensity and modality of the stimulus but also of prestimulus level of activation and its dependence on breathing behavior. At the same time there is evidence of a connection of HR with high cognitive processes which in an interaction of the organism and environment together with volitional processes have a regulatory function.     

Heart rate deceleration is not an orienting reflex; heart rate acceleration is not a defensive reflex

Graham and Clifton (1966) proposed an integration of Sokolov's theory of orienting and defensive reflexes with the stimulus intake/rejection dichotomy of the Laceys. This integration consisted of hypothesizing that heart rate deceleration is a measure of the orienting reflex, and that cardiac acceleration is a measure of the defensive reflex. This article demonstrates that Graham and Clifton failed to establish a valid integration of these two theories. This failure is a consequence of 1) their misconstruing Sokolov's theory, and 2) an inaccurate and selective review of the research literature then available. Consideration of more recent research would seem to rule out the possibility that their thesis was correct in spite of these flaws in its derivation. Cardiac responding in the OR context thus remains open to further investigation and interpretation.     

Effects of Music on the Recovery of Autonomic and Electrocortical Activity After Stress Induced by Aversive Visual Stimuli

The purpose of this study was to compare the effects of music and white noise on the recovery of physiological measures after stressful visual stimulation. Twenty-nine participants took part in the experiment. Visual stimulation with slides eliciting disgust was followed by subjectively pleasant music, sad music, and white noise in three consecutive sessions. The spectral power of the frontal and temporal EEG, skin conductance, heart rate, heart period variability, facial capillary blood flow, and respiration rate were recorded and analyzed. Aversive visual stimulation evoked heart rate deceleration, increased high frequency component of heart period variability, increased skin conductance level and skin conductance response frequency, decreased facial blood flow and velocity, decreased temporal slow alpha and increased frontal fast beta power in all three sessions. Both subjectively pleasant and sad music led to the restoration of baseline levels on most parameters; while white noise did not enhance the recovery process. The effects of pleasant music on post-stress recovery, when compared to white noise, were significantly different on heart rate, respiration rate, and peripheral blood flow. Both positive and negative music exerted positive modulatory effects on cardiovascular and respiratory activity, namely increased heart rate, balanced heart period variability, increased vascular blood flow and respiration rate during the post-stress recovery. Data only partially supported the “undoing” hypothesis, which states that positive emotions may facilitate the process of physiological recovery following negative emotions.     

Time and Encoding Effects in the Concealed Knowledge Test

Although the traditional “lie detector” test is used frequently in forensic contexts, it has (like most test of deception) some limitations. The concealed knowledge test (CKT) focuses on participants’ recognition of privileged knowledge rather than lying per-se and has been studied extensively using a variety of measures. A “guilty” suspect’s interaction with and memory of crimescene items may vary. Furthermore, memory for crimescene items may diminish over time. The interaction of encoding quality and test delay on CKT efficiency has been previously implied, but not yet demonstrated. We used a response-time based CKT to detect concealed knowledge from shallow and deep study procedures after 10-min, 24-h, and 1-week delays. Results show that more elaborately encoded information afforded higher detection accuracy than poorly encoded items. Although classification accuracy following deep study was unaffected by delay, detection of poorly elaborated information was initially high, but compromised after 1 week. Thus, choosing optimal test items requires considering both test delay and initial encoding level.     

Postnatal development of heart rate patterns elicited by an aversive CS and US in cats

Heart rate and motor responses were recorded in cats of different ages during classical conditioning. A deceleratory-acceleratory heart rate pattern observed during the CS-US interval in one- and four-week-old kittens is an alpha conditioned response, a potentiated original response to the CS. At eight weeks of age two new distinct patterns of pure acceleration or pure deceleration are acquired during conditioning and in the absence of motor learning. At 12 weeks of age and in adult subjects, heart rate patterns during the CS-US interval become more complex and conditioned motor responses can be observed. A covariance of HR acceleration and motor responses during the CS-US interval is absent in eight-week-old subjects, but quite high in 12-week-old subjects and adult cats. The data are interpreted as suggesting separate elicitatory mechanisms of HR and motor responses which may show synchrony later in ontogeny.     

Chronotropic responses to experimental ischemia of the canine sino auricular node.

(1) Using isolated, blood-perfused atrium preparation of dogs, the effect of ischemia on sinus rate was studied in ten preparations. Cessation of atrial perfusion usually induced gradual deceleration of the sinus rate which was not blocked by atropine. Occasionally, brief and slight sinus acceleration was initially observed in three of ten atrium preparations. This positive chronotropic effect was not blocked by a beta-adrenoceptor blocking agent, propranolol. (2) In every preparation, just after release of occlusion, there was an initial profound sinus deceleration, occasionally followed by oscillatory changes in sinus rate. (3) The chronotropic response pattern induced by temporary occlusion and release of the sinus node artery was not influenced by propranolol, phenoxybenzamine or atropine treatment. (4) These results suggest that ischemia exerts its principal effect directly on the sino auricular node pacemaker cells, rather than on neighboring nerve endings.     

Ontogenetic changes in pacemaker activity in chick heart

Pacemaker activity of the isolated chick heart changed considerably during development. The spontaneous impulse frequency increased up to the 11th–15th incubation day. This period of acceleration was followed by a marked deceleration around the time of hatching. Both acceleration and deceleration appeared to be caused by changes intrinsic to the pacemaker. Deceleration was related to a decrease in rate of slow diastolic depolarization. The results were compared with well-known ontogenetic changes in heart rate $\text{in vivo}$. This comparison indicates that the deceleration of pacemaker firing around hatching is counteracted by the development of sympathetic cardiac reflexes $\text{in vivo}$.     

Brain fingerprinting: a comprehensive tutorial review of detection of concealed information with event-related brain potentials

Brain fingerprinting (BF) detects concealed information stored in the brain by measuring brainwaves. A specific EEG event-related potential, a P300-MERMER, is elicited by stimuli that are significant in the present context. BF detects P300-MERMER responses to words/pictures relevant to a crime scene, terrorist training, bomb-making knowledge, etc. BF detects information by measuring cognitive information processing. BF does not detect lies, stress, or emotion. BF computes a determination of “information present” or “information absent” and a statistical confidence for each individual determination. Laboratory and field tests at the FBI, CIA, US Navy and elsewhere have resulted in 0% errors: no false positives and no false negatives. 100% of determinations made were correct. 3% of results have been “indeterminate.” BF has been applied in criminal cases and ruled admissible in court. Scientific standards for BF tests are discussed. Meeting the BF scientific standards is necessary for accuracy and validity. Alternative techniques that failed to meet the BF scientific standards produced low accuracy and susceptibility to countermeasures. BF is highly resistant to countermeasures. No one has beaten a BF test with countermeasures, despite a $100,000 reward for doing so. Principles of applying BF in the laboratory and the field are discussed.     

Dynamics of cardiac performance in athletes during isometric exercise

The main structural-functional indices of cardiac performance during isometric exercise were recorded in athletes and non-athletes. The physiological shifts in response to exercise were less obvious in the athletes than in the non-athletes. This was mainly determined by the structural features of the “athlete’s heart.” The dependence of a series of physiological indices on the heart rate was revealed: as cardiac rhythm increased in response to a submaximal isometric exercise, the systolic and, to a lesser degree, diastolic arterial pressure grew and the stroke volume of blood decreased.     

Spread of information through a population with socio-structural bias: I. Assumption of transitivity

A previously derived iteration formula for a random net was applied to some data on the spread of information through a population. It was found that if the axon density (the only free parameter in the formula) is determined by the first pair of experimental values, the predicted spread is much more rapid than the observed one. If the successive values of the “apparent axon density” are calculated from the successive experimental values, it is noticed that this quantity at first suffers a sharp drop from an initial high value to its lowest value and then gradually “recovers”. An attempt is made to account for this behavior of the apparent axon density in terms of the “assumption of transitivity”, based on a certain socio-structural bias, namely, that the likely contacts of two individuals who themselves have been in contact are expected to be strongly overlapping. The assumption of transitivity leads to a drop in the apparent axon density from an arbitrary initial value to the vicinity of unity (if the actual axon density is not too small). However, the “recovery” is not accounted for, and thus the predicted spread turns out to beslower than the observed.     

A note on the response characteristics of the extraocular muscle system

Using records of the response of the extraocular muscle system to a step input, the frequency response characteristics of the system have been calculated. They show a progressive reduction of gain for frequencies above 30–40 cps. The high frequency tremor of the eyes observed during “steady” fixation would thus be expected to be damped down and this is in fact borne out by frequency analyses of tremor records.     

The ‘Positive Effect’ Is Present in Older Chinese Adults: Evidence from an Eye Tracking Study

The ''Positive Effect'' is defined as the phenomenon of preferential cognitive processing of positive affective information, and avoidance or dismissal of negative affective information in the social environment. The ‘Positive Effect’ is found for older people compared with younger people in western societies and is believed to reflect a preference for positive emotional regulation in older adults. It is not known whether such an effect is Universal, and in East Asian cultures, there is a highly controversial debate concerning this question. In the current experiment we explored whether Chinese older participants showed a ''Positive Effect'' when they inspected picture pairs that were either a positive or a negative picture presented with a neutral picture, or a positive and negative picture paired together. The results indicated that both groups of participants showed an attentional bias to both pleasant (more processing of) and unpleasant pictures (initial orienting to) when these were paired with neutral pictures. When pleasant and unpleasant pictures were paired together both groups showed an initial orientation bias for the pleasant picture, but the older participants showed this bias for initial orienting and increased processing measures, providing evidence of a ‘Positive Effect’ in older Chinese adults.     

Regular heartbeat dynamics are associated with cardiac health

The human heartbeat series is more variable and, hence, more complex in healthy subjects than in congestive heart failure (CHF) patients. However, little is known about the complexity of the heart rate variations on a beat-to-beat basis. We present an analysis based on symbolic dynamics that focuses on the dynamic features of such beat-to-beat variations on a small time scale. The sequence of acceleration and deceleration of eight successive heartbeats is represented by a binary sequence consisting of ones and zeros. The regularity of such binary patterns is quantified using approximate entropy (ApEn). Holter electrocardiograms from 30 healthy subjects, 15 patients with CHF, and their surrogate data were analyzed with respect to the regularity of such binary sequences. The results are compared with spectral analysis and ApEn of heart rate variability. Counterintuitively, healthy subjects show a large amount of regular beat-to-beat patterns in addition to a considerable amount of irregular patterns. CHF patients show a predominance of one regular beat-to-beat pattern (alternation of acceleration and deceleration), as well as some irregular patterns similar to the patterns observed in the surrogate data. In healthy subjects, regular beat-to-beat patterns reflect the physiological adaptation to different activities, i.e., sympathetic modulation, whereas irregular patterns may arise from parasympathetic modulation. The patterns observed in CHF patients indicate a largely reduced influence of the autonomic nervous system. In conclusion, analysis of short beat-to-beat patterns with respect to regularity leads to a considerable increase of information compared with spectral analysis or ApEn of heart-rate variations.     

Connectivity and information transfer in flow networks: Two magic numbers in ecology?

An ecosystem can be visualized as a graph of certain preassigned trophic compartments; these nodes are then mutually connected through the internal exchanges of material and energy. The mathematical theory of information can be applied to such a graph in order to define two relevant indices: a measure of connectivity (the entropy H of the connections) and a measure of the degree of the “energetic” specialization (the internal transfer of informationI). The computation of these indices in stationary real cases suggests that the observed complexity of ecosystems is conditioned by two competing effects. The first can be interpreted as a “thermodynamical” principle related to the unavoidable irreversibility taking place inside the system, whereas the second can be taken as a “biological” principle concerned with the selection of some particular interactions: those which maximize the information circulating between the compartments.     

Is the Brain's Inertia for Motor Movements Different for Acceleration and Deceleration?

The brain''s ability to synchronize movements with external cues is used daily, yet neuroscience is far from a full understanding of the brain mechanisms that facilitate and set behavioral limits on these sequential performances. This functional magnetic resonance imaging (fMRI) study was designed to help understand the neural basis of behavioral performance differences on a synchronizing movement task during increasing (acceleration) and decreasing (deceleration) metronome rates. In the MRI scanner, subjects were instructed to tap their right index finger on a response box in synchrony to visual cues presented on a display screen. The tapping rate varied either continuously or in discrete steps ranging from 0.5 Hz to 3 Hz. Subjects were able to synchronize better during continuously accelerating rhythms than in continuously or discretely decelerating rhythms. The fMRI data revealed that the precuneus was activated more during continuous deceleration than during acceleration with the hysteresis effect significant at rhythm rates above 1 Hz. From the behavioral data, two performance measures, tapping rate and synchrony index, were derived to further analyze the relative brain activity during acceleration and deceleration of rhythms. Tapping rate was associated with a greater brain activity during deceleration in the cerebellum, superior temporal gyrus and parahippocampal gyrus. Synchrony index was associated with a greater activity during the continuous acceleration phase than during the continuous deceleration or discrete acceleration phases in a distributed network of regions including the prefrontal cortex and precuneus. These results indicate that the brain''s inertia for movement is different for acceleration and deceleration, which may have implications in understanding the origin of our perceptual and behavioral limits.     

Using sensory weighting to model the influence of canal,otolith and visual cues on spatial orientation and eye movements

 The sensory weighting model is a general model of sensory integration that consists of three processing layers. First, each sensor provides the central nervous system (CNS) with information regarding a specific physical variable. Due to sensor dynamics, this measure is only reliable for the frequency range over which the sensor is accurate. Therefore, we hypothesize that the CNS improves on the reliability of the individual sensor outside this frequency range by using information from other sensors, a process referred to as “frequency completion.” Frequency completion uses internal models of sensory dynamics. This “improved” sensory signal is designated as the “sensory estimate” of the physical variable. Second, before being combined, information with different physical meanings is first transformed into a common representation; sensory estimates are converted to intermediate estimates. This conversion uses internal models of body dynamics and physical relationships. Third, several sensory systems may provide information about the same physical variable (e.g., semicircular canals and vision both measure self-rotation). Therefore, we hypothesize that the “central estimate” of a physical variable is computed as a weighted sum of all available intermediate estimates of this physical variable, a process referred to as “multicue weighted averaging.” The resulting central estimate is fed back to the first two layers. The sensory weighting model is applied to three-dimensional (3D) visual–vestibular interactions and their associated eye movements and perceptual responses. The model inputs are 3D angular and translational stimuli. The sensory inputs are the 3D sensory signals coming from the semicircular canals, otolith organs, and the visual system. The angular and translational components of visual movement are assumed to be available as separate stimuli measured by the visual system using retinal slip and image deformation. In addition, both tonic (“regular”) and phasic (“irregular”) otolithic afferents are implemented. Whereas neither tonic nor phasic otolithic afferents distinguish gravity from linear acceleration, the model uses tonic afferents to estimate gravity and phasic afferents to estimate linear acceleration. The model outputs are the internal estimates of physical motion variables and 3D slow-phase eye movements. The model also includes a smooth pursuit module. The model matches eye responses and perceptual effects measured during various motion paradigms in darkness (e.g., centered and eccentric yaw rotation about an earth-vertical axis, yaw rotation about an earth-horizontal axis) and with visual cues (e.g., stabilized visual stimulation or optokinetic stimulation). Received: 20 September 2000 / Accepted in revised form: 28 September 2001     

Promotive effect of 5-aminolevulinic acid on chlorophyll,antioxidative enzymes and photosynthesis of Pakchoi (<Emphasis Type="Italic">Brassica campestris</Emphasis> ssp<Emphasis Type="Italic">.</Emphasis><Emphasis Type="Italic">chinensis</Emphasis> var. communis Tsen et Lee)

The objective of this article is to study the effect of 5-aminolevulinic acid (ALA) and enhanced chlorophyll content, antioxidative enzymes and photosynthesis rate by foliar application of ALA. We evaluated three concentrations (control-distilled water, T1-50 mg l⁻¹, T2-150 mg l⁻¹, T3-250 mg l⁻¹) of ALA and seven cultivars, “Sanchidaye” (Sa-1), “Lichuandasuomian” (Li-1), “Aijiaohuang” (Ai-1), “Qingyou” No. 4 (Qi-1), “Aikang” No. 5 (Ak-1), “Hanxiao” (Ha-1) and “Shulv” (Sl-1). “Ak-1” showed strongest response of POD (peroxidase) enzyme activity (0.4 U g⁻¹ min⁻¹) in 250 mg l⁻¹ ALA solution. The highest CAT (catalase) activity (0.8 U g⁻¹ min⁻¹) after administration of 250 mg l⁻¹ ALA was observed in “Li-1”. Meanwhile, highest (1.42 mg l⁻¹) total chlorophyll content was also observed in “Ak-1”, when leaves were treated in 50 mg l⁻¹ ALA, “Li-1” and “Ai-1” showed strongest response of specific activity of superoxide dismutase (SOD) in 50 mg l⁻¹ and 50 mg l⁻¹ ALA. Two hundred and fifty milligram per milliliter of ALA-treatment significantly improved the net photosynthetic rate.     

Light-induced swimming of Daphnia: can laboratory experiments predict diel vertical migration?

Vertical displacement velocity of a Daphniagaleata × hyalina clone was quantified inrelation to changes in the relative rate of lightchange. An increase in the latter variable triggers anenhanced swimming response, and this response is againelicited when a second increase in the rate ofrelative light increase is applied. Decreases in therate of light increase affect phototactic swimming ina similar way. The acceleration/deceleration assistedstimulus-response system is an extension of the ideaof phototaxis as the underlying behavioural mechanismfor vertical migration, and suggests that continuousaccelerations in light change also affect verticaldisplacements observed in the field. A simple dielvertical migration simulation model was used tocalculate the vertical displacement of Daphniain relation to the natural light change at sunrise.The calculated vertical displacement fits nicely inthe temporal range of the observed averaged downwardmigration of adult Daphnia in Lake Maarsseveen.The calculated migration amplitude, however, islarger than the change in mean population depthobserved in nature.