Head-turning Response Research Articles

Vascular Underpinnings of Cerebral Lateralisation in the Neonate

Traditionally, adult and neonatal cerebral perfusion have been presumed to be symmetrical. Contrary to this, our adult work shows that supra-aortic cerebral supply is systematically biased towards the left, in terms of both vessel geometry and blood flow volumes. Although this asymmetry is meaningfully related to hand preference, the developmental origins of this association remain unknown. Our detailed investigations of the cerebral vasculature confirm analogous asymmetries in term neonates. Specifically, we demonstrate that the structure and flow of neonatal middle cerebral vessels are consistently asymmetric and predominantly left-dominant. Building on our work from the same cohort, we now report further analyses of these new-found asymmetries. Namely, exploring for the first time, the relationship between arterial lateral biases and the neonatal head-turning response—a reliable early behavioural precursor of handedness that shows a systematic rightward bias in the population. Here, we demonstrate a contralateral relationship between vessel morphology and primitive expressions of lateralisation that predate the establishment of definitive handedness in the course of postnatal development. This relationship mimics patterns observed in adults and suggests that lateralising trends in angiogenesis may ultimately influence the emergence of human lateral preferences.

Dopamine modulates the optomotor response to unreliable visual stimuli in Drosophila melanogaster.

State-dependent modulation of sensory systems has been studied in many organisms and is possibly mediated through neuromodulators such as monoamine neurotransmitters. Among these, dopamine is involved in many aspects of animal behaviour, including movement control, attention, motivation and cognition. However, the precise neural mechanism underlying dopaminergic modulation of behaviour induced by sensory stimuli remains poorly understood. Here, we used Drosophila melanogaster to show that dopamine can modulate the optomotor response to moving visual stimuli including noise. The optomotor response is the head-turning response to moving objects, which is observed in most sight-reliant animals including mammals and insects. First, the effects of the dopamine system on the optomotor response were investigated in mutant flies deficient in dopamine receptors D1R1 or D1R2, which are involved in the modulation of sleep-arousal in flies. We examined the optomotor response in D1R1 knockout (D1R1 KO) and D1R2 knockout (D1R2 KO) flies and found that it was not affected in D1R1 KO flies; however, it was significantly reduced in D1R2 KO flies compared with the wild type. Using cell-type-specific expression of an RNA interference construct of D1R2, we identified the fan-shaped body, a part of the central complex, responsible for dopamine-mediated modulation of the optomotor response. In particular, pontine cells in the fan-shaped body seemed important in the modulation of the optomotor response, and their neural activity was required for the optomotor response. These results suggest a novel role of the central complex in the modulation of a behaviour based on the processing of sensory stimulations.

Role of audiovisual synchrony in driving head orienting responses

Many studies now suggest that optimal multisensory integration sometimes occurs under conditions where auditory and visual stimuli are presented asynchronously (i.e. at asynchronies of 100 ms or more). Such observations lead to the suggestion that participants' speeded orienting responses might be enhanced following the presentation of asynchronous (as compared to synchronous) peripheral audiovisual spatial cues. Here, we report a series of three experiments designed to investigate this issue. Upon establishing the effectiveness of bimodal cuing over the best of its unimodal components (Experiment 1), participants had to make speeded head-turning or steering (wheel-turning) responses toward the cued direction (Experiment 2), or an incompatible response away from the cue (Experiment 3), in response to random peripheral audiovisual stimuli presented at stimulus onset asynchronies ranging from -100 to 100 ms. Race model inequality analysis of the results (Experiment 1) revealed different mechanisms underlying the observed multisensory facilitation of participants' head-turning versus steering responses. In Experiments 2 and 3, the synchronous presentation of the component auditory and visual cues gave rise to the largest facilitation of participants' response latencies. Intriguingly, when the participants had to subjectively judge the simultaneity of the audiovisual stimuli, the point of subjective simultaneity occurred when the auditory stimulus lagged behind the visual stimulus by 22 ms. Taken together, these results appear to suggest that the maximally beneficial behavioural (head and manual) orienting responses resulting from peripherally presented audiovisual stimuli occur when the component signals are presented in synchrony. These findings suggest that while the brain uses precise temporal synchrony in order to control its orienting responses, the system that the human brain uses to consciously judge synchrony appears to be less fine tuned.

Using Peripersonal Warning Signals to Orient a Driver’s Gaze

We report a series of three experiments designed to assess the relative speed with which people can initiate speeded head-orienting responses following the presentation of spatial warning signals. Recent cognitive neuroscience findings have shown that the human brain tends to treat stimuli occurring in peripersonal space as being somehow more behaviorally relevant and attention demanding than stimuli occurring in extrapersonal space. These brain mechanisms may be exploited in the design of warning signals. Experiment 1 assessed the effectiveness of various different unisensory warning signals in eliciting a head-turning response to look at the potential source of danger requiring participants' immediate attention; Experiment 2 assessed the latency of a driver's responses to events occurring in the cued direction; Experiment 3 assessed the relative effectiveness of various warning signals in reorienting a person's gaze back to a central driving task while he or she was distracted by a secondary task. The results show that participants initiated head-turning movements and made speeded discrimination or braking responses significantly more rapidly following the presentation of a close rear auditory warning signal than following the presentation of either a far frontal auditory warning signal, a vibrotactile warning signal presented to their waist, or a peripheral visual warning signal. These results support the claim that the introduction of peripersonal warning signals results in a significant performance advantage relative to traditionally designed warnings. Warning systems that have been designed around the constraints of the human brain offer great potential in the future design ofmultisensory interfaces.

Assessing Speech Pattern Contrast Perception in Infants

To assess perception of specific speech pattern contrasts in infants with normal hearing (NH) and infants with sensorineural hearing loss (HL). Prospective longitudinal and cross-sectional study. Tertiary referral center. Nine infants with NH and 11 infants with HL ranging from mild to profound. Speech pattern contrast perception was evaluated in infants with NH and HL using a new behavioral test called Visual Reinforcement Assessment of the Perception of Speech Pattern Contrasts (VRASPAC). VRASPAC assesses the infant's ability to distinguish the speech features of vowel height and place and consonant voicing, continuance, and place. Detection of a phonetic change is indicated by a conditioned head-turn response. Performance is reported as the percent confidence that responses are not random. The infants with NH attained high confidence scores for the vowel height and place contrasts used in this study. The infants with HL achieved high scores for the vowel height contrast regardless of degree of hearing loss. High scores were attained for the vowel place contrast by infants with losses less than 60 dB HL. Performance for the consonant contrasts was variable for all of the infants. Results from 1 infant assessed precochlear and postcochlear implantation indicated substantial improvement in speech pattern contrast perception with the implant. Perception of speech pattern contrasts in infants, particularly for the vowel contrasts, can be evaluated with a high level of confidence using VRASPAC. Consonant contrast perception is much more variable than vowel contrast perception and requires further investigation.

The Steenland Era

If science and argument benefit from each other, then it is not surprising that the Steenland era was robust for exploration, whether one agreed or disagreed with his famous and often controversial points of view. Nelson Steenland (1919-2000) was one of several outstanding graduates of Maurice Ewing's geophysical program at Columbia University (see his biographical sidebar to this article), and he entered the geophysical profession with a new PhD in 1949, perfect timing to engage in the fledgling development of the airborne magnetometer. Not only was Steenland's impact on the aeromagnetic enterprise significant (no doubt, only a few would disagree), but also his influence on the whole of oil and gas exploration was remarkable (many may disagree with me here). Unfortunately, he will not have an opportunity to write one of his head-turning responses to this article, so I will quote him with some frequency in what follows.

Human Newborns Prefer Human Milk: Conspecific Milk Odor Is Attractive Without Postnatal Exposure

Behavioral responses of 3- to 4-day-old newborns to the odors of various human milk (HM) and formula milk (FM) were examined in paired-choice tests. When both stimuli were nonfamiliar, breast-fed, as well as bottle-fed, infants oriented their head and mouthed more vigorously to HM than to FM. When breast-fed infants were exposed to nonfamiliar HM along with the familiar FM, their head-turning responses were undifferentiated although they mouthed more frequently to the human stimulus. When nonfamiliar HM and familiar FM were equalized in intensity, nonfamiliar HM again elicited more head orientation and mouthing responses. These results demonstrate that the odor of HM is more attractive to human newborns than FM and that this preference is independent of postnatal feeding experience.

Perception of phonetic contrasts in infants: development of the VRASPAC

The VRASPAC (visual reinforcement assessment of the perception of speech pattern contrasts) is a test that assesses auditory perception of phonologically significant contrasts in infants by combining the visual reinforcement and change/no-change techniques with the speech pattern contrast concept. The contrasts convey vowel height, vowel place, and consonant voicing, manner and place. The infant habituates to a continuous repetition of a standard nonsense syllable and then is conditioned to respond, via head-turn response, to a contrasting syllable. Animated toys or cartoon images serve as the reinforcement. To date, 10 children have been tested on two early versions of the test; six children with normal hearing (9–34 months), two children with mild or moderate hearing loss using hearing aids (11–17 months), and two children with profound hearing loss using cochlear implants (36–38 months). The normal-hearing children responded consistently to the vowel and consonant contrasts. The hearing-impaired children responded consistently to vowel height only. Preliminary results suggest that the VRASPAC is a viable test for infants as young as 9 months and that performance is dependent on phonological development.

Task-dependent visual coding of sound position in visuospatial neglect patients.

Recent neurophysiological evidence has shown that sound position can be coded in multiple frames of reference in the animal brain (i.e. head-centred, eye-centred, or intermediate head/eye centred). Here, we provide evidence for multiple coding of sound positions in humans, by studying pointing to sounds in 14 right brain-damaged (RBD) patients with or without visual neglect (a visuospatial neurological disturbance typically affecting contralesional space). Patients were asked to indicate the position of free-field sounds, either with a hand-pointing or with a head-turning response. Pointing movements were performed either blindfolded or with eyes open, but no visual feedback was available about sound position or the motor response. All RBD patients showed some impairment in sound localisation, particularly for sounds towards the contralesional side. In addition, task-irrelevant vision was more detrimental for hand-pointing than head-turning responses, only for neglect patients. We propose that this finding reflects visual coding of sound position when the eyes are open, which extends the pathological visuospatial bias of neglect patients to sound localisation. Moreover, the absence of any modulatory effects of ambient vision when head-turning responses were adopted suggests task-dependent visual coding of sound position, in agreement with multiple frames of reference for sound localisation.

Using visual reinforcement audiometry in the assessment of hearing in infants

Using visual reinforcement audiometry in the assessment of hearing in infants

Developmental Pathways of Children With and Without Familial Risk for Dyslexia During the First Years of Life

Comparisons of the developmental pathways of the first 5 years of life for children with (N = 107) and without (N = 93) familial risk for dyslexia observed in the Jyvaskyla Longitudinal study of Dyslexia are reviewed. The earliest differences between groups were found at the ages of a few days and at 6 months in brain event-related potential responses to speech sounds and in head-turn responses (at 6 months), conditioned to reflect categorical perception of speech stimuli. The development of vocalization and motor behavior, based on parental report of the time of reaching significant milestones, or the growth of vocabulary (using the MacArthur Communicative Development Inventories) failed to reveal differences before age 2. Similarly, no group differences were found in cognitive and language development assessed by the Bayley Scales of Infant Development and the Reynell Developmental Language Scales before age 2.5. The earliest language measure that showed lower scores among the at-risk group was maximum sentence length at age 2. Early gross motor development had higher correlation to later language skills among the at-risk group rather than the control children. The most consistent predictor of differential development between groups was the onset of talking. Children who were identified as late talkers at age 2 were still delayed at the age 3.5 in most features of language-related skills-but only if they belonged to the group at familial risk for dyslexia. Several phonological and naming measures known to correlate with reading from preschool age differentiated the groups consistently from age 3.5. Our findings imply that a marked proportion of children at familial risk for dyslexia follow atypical neurodevelopmental paths. The signs listed previously comprise a pool of candidates for early predictors and precursors of dyslexia, which await validation.

How do owls localize interaurally phase-ambiguous signals?

Owls and other animals, including humans, use the difference in arrival time of sounds between the ears to determine the direction of a sound source in the horizontal plane. When an interaural time difference (ITD) is conveyed by a narrowband signal such as a tone, human beings may fail to derive the direction represented by that ITD. This is because they cannot distinguish the true ITD contained in the signal from its phase equivalents that are ITD +/- nT, where T is the period of the stimulus tone and n is an integer. This uncertainty is called phase-ambiguity. All ITD-sensitive neurons in birds and mammals respond to an ITD and its phase equivalents when the ITD is contained in narrowband signals. It is not known, however, if these animals show phase-ambiguity in the localization of narrowband signals. The present work shows that barn owls (Tyto alba) experience phase-ambiguity in the localization of tones delivered by earphones. We used sound-induced head-turning responses to measure the sound-source directions perceived by two owls. In both owls, head-turning angles varied as a sinusoidal function of ITD. One owl always pointed to the direction represented by the smaller of the two ITDs, whereas a second owl always chose the direction represented by the larger ITD (i.e., ITD - T).

Olfactory function in the human fetus: Evidence from selective neonatal responsiveness to the odor of amniotic fluid.

This study was aimed at characterizing the level of specificity of the human newborn's response to an odor experienced in utero. Three groups of breast-fed infants and 3 groups of bottle-fed infants were examined on Postnatal Day 3 for their differential head-turning response when exposed to paired-choice tests contrasting the odors of either familiar (f) amniotic fluid (AF) or nonfamiliar (nf) AF or either of these AF odors and a control (C) stimulus. In fAF versus nfAF tests, the infants oriented preferentially to the odor of fAF, regardless of their feeding regimen (i.e., of their postnatal reexposure to AF-like cues in maternal milk). The fAF or nfAF versus C tests showed that this response pattern was caused by a true positive orientation toward fAF and not by avoidance from nfAF odor. This highly selective neonatal response to fAF odor is consistent with the hypothesis that the human fetus can detect and store the unique chemosensory information available in the prenatal environment and that this information becomes coupled with positive control of behavior.

Identification of a new contingency-based response in honey bees (Apis mellifera) through revision of the proboscis extension conditioning paradigm

The two experiments reported present new information in the area of classical conditioning experiments with honey bees. Experiment 1 establishes a single unconditioned stimulus (US) technique as a preferred technique for conditioning of the proboscis extension response. Experiment 1 further identifies a new head turn response which occurs when the standard compound US technique is used. Experiment 2 demonstrates that the newly identified head turn response is contingency-based and provides important new response to the repertoire of honey bee learning experiments.

Adding Objectivity to Infant Behavioral Audiometry

This article deals with the limitations of infant behavioral audiometry, which have led us to seek objective methods of audiometry for determining hearing sensitivity in infants. It describes efforts to add objectivity to (or reduce the subjectivity of) behavioral methods of infant audiometry. Several aspects of visual reinforcement audiometry (VRA), including the head turn response, the use of control trials, and adherence to the principles of operant conditioning, serve to reduce the subjectivity inherent in behavior observation audiometry. In addition, computer control of VRA procedures can relieve the examiner of potentially subjective decision-making during the course of evaluation and can facilitate testing with sophisticated algorithms that could not be done manually by a single examiner. Computer simulations to determine the best VRA test parameters are described.

Appetitive feeding behavior of Aplysia: behavioral and neural analysis of directed head turning

The appetitive phase of feeding behavior in Aplysia consists of a behavioral sequence in which the quiescent animal starts to locomote and then assumes a characteristic feeding posture. In this position, head-turning responses can be elicited by a localized food stimulus (seaweed) delivered to the lips or tentacles. In response to brief (open loop) stimulation with seaweed, the animal turns toward the stimulus but greatly overshoots the target. However, the angular velocity and the final turning angle are a function of the eccentricity of the stimulus, progressively increasing with greater eccentricities. In a food-aroused animal, a brief tactile stimulus evokes turning and biting responses similar to those triggered by seaweed, which provides both tactile and chemical stimulation. Upon repeated tactile stimulation, however, the response magnitude decrements rapidly, whereas the magnitude remains high when turning responses are repeatedly elicited by food stimuli. A purely chemical stimulus sometimes can elicit a turning response, but chemical stimuli alone are much less efficacious than tactile stimuli alone. When the stimulus is maintained in a stationary position (closed loop), the animal turns until its mouth is oriented over the food. A turning response to a lateral stimulus can be reduced by an immediately following medial stimulus. To explain the above findings, we propose a form of response substitution, in which the response to the first, lateral stimulus is substituted by a weaker response to a more medial stimulus. No turning response is evoked when the animal is stimulated while performing spontaneous or evoked bites, though biting per se does not interrupt ongoing turning movements. In animals with lesions of the cerebral-buccal connectives, a food stimulus on the mouth is also followed by a reduction of the capacity of stimuli to elicit turning responses. In these lesioned animals, the food stimulus appears to elicit a bite command, though the biting behavior itself does not occur. Thus, it appears that the bite-related gating of stimuli is of cerebral origin, rather than due to the generation of the buccal motor program. The force necessary to power the turning movements was calculated from the trajectories of the movements. The results indicate that a power phase during the first half of the duration of the total movement is sufficient to generate a turn. The power phase can be followed by a brief gliding phase, and finally the movement appears to be actively terminated.(ABSTRACT TRUNCATED AT 400 WORDS)

A device to measure head-turn reflex in the distraction test used for infant hearing assessment

A device was constructed to measure infant head rotation during orienting reflexes to sound stimuli. An experiment was devised to compare the device output with visual observation of the infant. Four stimulus and four no-stimulus control trials were presented randomly to each of 24 infants. Fourteen scorers examined a hardcopy record of the device output followed by a video of the same tests for the presence of head-turn responses to the sound stimuli. The results of this study have shown that it is possible to construct a device to detect head-turn reflexes from young children. However, the success rate in detecting head-turns was inferior to visual scoring of the video of the child's behavior. This was due to the lack of precision of the device. An improved device may overcome this problem and could provide the basis for a useful addition to distraction testing.

A subpopulation of cerebral B cluster neurones ofAplysia californicais involved in defensive head withdrawal but not appetitive head movements

ABSTRACTThe cerebral B cluster neurones of Aplysia californica were studied under experimental conditions designed to evoke head movements in a selective fashion: either to approach an appetitive stimulus, or to withdraw from an aversive one. Intracellular recordings indicated the presence of two types of B cluster neurones: Bn cells that had fast (narrow) spikes, and Bb cells that had slow (broad) spikes. Tactile stimulation of the tentacles, rhinophores and lips excited Bn neurones, but inhibited Bb neurones. Intracellular stimulation of Bn cells evoked contractions of body wall muscles. No contractions were observed when Bb cells were fired, indicating that it is unlikely that the Bb neurones are motor neurones. Several lines of evidence indicated that the Bn type neurones are involved in withdrawal responses but not in appetitive head turning. (1) Elimination of the descending axons of the Bn cells by lesioning the cerebropleural connectives (C-Pl connectives) did not affect the head-turning response. This lesion significantly altered the head-withdrawal response by selectively eliminating an initial fast component of the withdrawal movement. (2) In chronic recordings from the C-Pl connective, unit activity was obtained which was correlated with the presentation of an appetitive stimulus rather than with evoked or spontaneous turning movements. A substantial increase in activity also occurred during head withdrawal of the animal. On the basis of these data, we postulate that separate populations of motor neurones are responsible for the aversive withdrawal of the head, and for the directed turning response towards a stimulus.

The development of a human auditory localization response: A U-shaped function.

Research during the past 10 years on the neonatal head-turn response to off-centred rattle sounds is reviewed, and various procedural and stimulus conditions that influence the probability of eliciting a correct response are identified. Also, the existence of a U-shaped developmental function is confirmed in a cross-sectional study of 104 infants between 3 days and 7 months of age. Neonates responded reliably, but slowly; the response decreased in frequency and magnitude between 1-3 months of age and increased again by 4-5 months of age. Speculation that this U-shaped function reflects a maturational shift in locus of control from subcortical to cortical structures was supported by the infants' responses to the presence effect (PE), which is thought to be cortically mediated. The PE was produced by playing the rattle sound through two loudspeakers with the output of one delayed by 5 ms, relative to the other; adults perceive only one sound at the leading loudspeaker. As predicted, neonates failed to respond to the PE, and the onset of correct PE responses corresponded closely to the upswing in the U-shaped function for SS responses. Other explanations for the temporary decline in orientation responses to sound are also discussed.

S(+)methylenedioxy-N-n-propylnoraporphine: an orally active inhibitor of dopamine selective for rat limbic system

The 10–11-methylenedioxy (MDO) derivative of S(+)N-n-propylnorapomorphine (NPA) was prepared and tested as a possible active prodrug to S(+)NPA, which we have recently found to exert in vivo activity suggestive of selective antagonism of dopamine receptors in the limbic forebrain but not the extrapyramidal basal ganglia. Like S(+)NPA, S(+)MDO-NPA inhibited the behavioral arousal induced by dopamine injected into nucleus accumbens of the rat, but not the head-turning response to dopamine injected into the corpus striatum. However, only MDO-NPA was orally active and it was somewhat longer-acting than NPA. The activity of S(+)MDO-NPA was prevented by pretreatment with the oxidase inhibitor SKF-525A. These properties are analogous to those of R(−)MDO-NPA, which we had previously reported as an orally active prodrug of the dopamine agonist R(−)NPA. Thus the methylenedioxy derivatives of the two entantiomers of NPA have properties desirable in a potentially clinically useful dopamine agonist and limbic dopamine antagonist, respectively.