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Epileptic Disorders : International... Oct 2022The Moro reflex (MR) is a primitive reflex that disappears after the first three months of life. It was described by the Austrian paediatrician Ernst Moro (1874-1951) in...
The Moro reflex (MR) is a primitive reflex that disappears after the first three months of life. It was described by the Austrian paediatrician Ernst Moro (1874-1951) in 1918, although the earliest visual representation of the MR dates back to the first half of the 14th Century, in a fresco by Ambrogio Lorenzetti (1290-1348). The neural centre underlying the MR is located in the lower part of the brainstem since it can be elicited also in anencephalic infants, as shown by the Austrian neurologist Eduard Gamper (1887-1938) in the first medical description of anencephaly (1926). The MR is due to the activation of an archaic neural circuit present in the newborn, the activity of which is later inhibited by the upper brain structures. Given their semiological resemblance, epileptic spasms and generalized tonic-clonic seizures might be due (at least partly) to the pathological activation of the same neural archaic circuit involved in the genesis of the MR. The neuronal network underlying these different phenomena might be located in the pons. In these seizure types, the activation of the same neural circuitry involved in the MR could occur through either direct excitation or through an indirect "liberating" mechanism, secondary to epileptic disruption of cortical inhibitory control on subcortical structures. The movements of the upper extremities in epileptic spasms, in the initial phase of generalized tonic-clonic seizures, and the MR might involve a distinct neural circuitry, which is (or becomes) hyperexcitable as a consequence of a pathological condition (epilepsy) or physiological brain immaturity (the MR).
Topics: Electroencephalography; Epilepsy; Epilepsy, Tonic-Clonic; Humans; Infant; Infant, Newborn; Reflex, Startle; Seizures; Spasm; Spasms, Infantile
PubMed: 35904039
DOI: 10.1684/epd.2022.1471 -
Infant Behavior & Development Feb 2017To propose a phylogenetic significance to the Moro reflex which remains unexplained since its publication in 1918 because both hands are free at the end of the gesture.
OBJECTIVE
To propose a phylogenetic significance to the Moro reflex which remains unexplained since its publication in 1918 because both hands are free at the end of the gesture.
METHOD
Among the 75 videos of healthy term newborns we have filmed in a research project on antenatal education to parenthood, we describe a sequence that clearly showed the successive movements of the Moro reflex and we report the occurrence of this reflex in the videos that were recorded from Time 0 of birth defined as the moment that lies between the birth of the thorax and the pelvis of the infant.
RESULTS
The selected sequence showed the following succession of the newborn's actions: quick extension-adduction of both arms, the orientation of the body, head and eyes towards a human person, and full extension-abduction of both arms with spreading of the fingers, crying and a distressed face. There were 13 Moro reflexes between 2 and 14s from Time 0 of birth. We found a significant association between the occurrence of the Moro reflex and the placement of the newborn at birth in supine position on the mother's abdomen (p=0.002).
DISCUSSION
The quick extension-adduction of both arms which started the sequence may be considered as a startle reflex controlled by the neural fear system and the arm extension-adduction which followed as a Moro reflex. The characteristics of all Moro reflexes were those of ritualization: amplitude, duration, stereotype of the gestures. This evolutionary process turns a physiological behavior, grasping in this case, to a non-verbal communicative behavior whose meaning is a request to be picked up in the arms. The gestures associated with the Moro reflex: crying and orientation of the body, head, and eyes towards a human person, are gestures of intention to communicate which support our hypothesis. The neural mechanism of the Moro reaction probably involves both the fear and the separation-distress systems.
CONCLUSION
This paper proposes for the first time a phylogenetic significance to the Moro reflex: a ritualized behavior of nonverbal communication. Professionals should avoid stimulating the newborns' fear system by unnecessarily triggering Moro reflexes. Antenatal education should teach parents to respond to the Moro reflexes of their newborn infant by picking her up in their arms with mother talk.
Topics: Crying; Fear; Female; Humans; Infant; Infant, Newborn; Male; Movement; Nonverbal Communication; Phylogeny; Reflex; Reflex, Startle; Video Recording
PubMed: 28222331
DOI: 10.1016/j.infbeh.2017.01.004 -
Cerebral Palsy Bulletin 1960
Topics: Birth Injuries; Child; Humans; Infant; Infant, Newborn; Intellectual Disability; Nervous System Physiological Phenomena; Neurology; Psychological Tests; Reflex; Reflex, Startle
PubMed: 13771355
DOI: No ID Found -
European Journal of Paediatric... 1998
Topics: Acoustic Stimulation; Animals; Behavior, Animal; Habituation, Psychophysiologic; Humans; Infant; Infant, Newborn; Inhibition, Psychological; Reflex; Reflex, Startle
PubMed: 10724105
DOI: 10.1016/s1090-3798(98)80050-0 -
European Journal of Paediatric... 1997
Topics: Animals; Humans; Infant, Newborn; Reflex, Startle; Spiders
PubMed: 10728219
DOI: 10.1016/s1090-3798(97)80034-7 -
Current Opinion in Neurobiology Feb 2019Learning is essential for animal survival under changing environments. Even in its simplest form, learning involves interactions between a handful of neuronal circuits,... (Review)
Review
Learning is essential for animal survival under changing environments. Even in its simplest form, learning involves interactions between a handful of neuronal circuits, hundreds of neurons and many thousand synapses. In this review I will focus on habituation - a form of non-associative learning during which organisms decrease their response to repetitions of identical sensory stimuli. I will discuss how recent studies of the acoustic startle reflex mediated by the Mauthner cell in the zebrafish larva are helping to understand the neuroplastic processes that underlie habituation. In addition to being a fascinating biological process, habituation is clinically relevant because it is affected in various neuropsychiatric disorders in humans, including autism, schizophrenia, Fragile-X and Tourette's syndromes.
Topics: Acoustic Stimulation; Animals; Larva; Learning; Neuronal Plasticity; Reflex, Startle; Zebrafish
PubMed: 30359930
DOI: 10.1016/j.conb.2018.10.004 -
Clinical Neurophysiology : Official... Jan 2012The origin of the startle reflex lies in the caudal brainstem; it can be elicited by an unexpected stimulus resulting in a bilateral activation of many muscles. Two... (Review)
Review
The origin of the startle reflex lies in the caudal brainstem; it can be elicited by an unexpected stimulus resulting in a bilateral activation of many muscles. Two subsequent responses can be measured during EMG recordings; after the initial motor reflex, lasting until about 150 ms, a second response can occur. The second response contains more emotional and voluntary behavioral responses. Clinically, syndromes with hyperstartling as common feature can be divided into three groups: hyperekplexia, stimulus-induced disorders, and neuropsychiatric disorders. Classification of startle syndromes within these three groups remains challenging. Generalized stiffness at birth, excessive startling and temporary generalized stiffness after being startled point towards hyperekplexia. Stimulus-induced disorders are distinguished by careful clinical and neurophysiological evaluation, including video recordings. Neuropsychiatric disorders usually have additional behavioural and psychiatric symptoms. Polymyographic EMG startle recordings exhibit an exaggeration of the initial motor startle reflex in hyperekplexia, while neuropsychiatric startle syndromes demonstrate a variable response pattern and abnormal behavioural features. Neurophysiological investigation of the startle reflex can help to further delineate between the startle syndromes and unravel the aetiology of neuropsychiatric startle disorders.
Topics: Animals; Brain Stem; Electromyography; Humans; Movement; Muscle Rigidity; Rats; Reflex, Abnormal; Reflex, Startle
PubMed: 22033030
DOI: 10.1016/j.clinph.2011.09.022 -
Pediatrics May 1964
Topics: Arm; Biomedical Research; Brain Diseases; Diagnosis; Hearing; Hearing Tests; History; Humans; Infant; Infant, Newborn; Leg; Motion Pictures; Movement; Physiology; Reflex; Reflex, Startle; Statistics as Topic
PubMed: 14143278
DOI: No ID Found -
Clinical Neurophysiology : Official... Sep 2003To provide an overview of startle reflex methodologies applied to the examination of emotional and motivational states in humans and to review the findings in different... (Review)
Review
OBJECTIVE
To provide an overview of startle reflex methodologies applied to the examination of emotional and motivational states in humans and to review the findings in different forms of psychopathology.
METHODS
Pertinent articles were searched mostly via MEDLINE and PsycINFO.
RESULTS
The startle reflex is a non-invasive translational tool of research that bridges the gap between animal and human investigations. Startle is used to study fear and anxiety, affective disturbances, sensitization, motivational states, and homeostasis.
CONCLUSIONS
The startle reflex is highly sensitive to various factors that are of interest in the studies of emotional disorders and has promoted new areas of investigations in psychiatry. However, research in psychiatry is still in its infancy and most findings await replication. Future progress will benefit from the development of innovative and powerful designs tailored to investigate specific disorders.
SIGNIFICANCE
The startle reflex has utility as a research tool to examine trauma-related disorders, fear learning, drug addiction, and to contrast affective states and emotional processing across diagnostic groups, but its usefulness as a diagnostic tool is limited.
Topics: Animals; Anxiety Disorders; Emotions; Humans; MEDLINE; Motivation; Psychiatry; Psychophysiology; Reflex; Reflex, Startle; Substance-Related Disorders
PubMed: 12948786
DOI: 10.1016/s1388-2457(03)00202-5 -
The International Journal of Eating... Mar 2019Patients with anorexia nervosa (AN) often show difficulties in the perception, expression, and regulation of emotions and a strong avoidance of aversive feelings....
OBJECTIVE
Patients with anorexia nervosa (AN) often show difficulties in the perception, expression, and regulation of emotions and a strong avoidance of aversive feelings. According to psychobiological models, dietary restraint and accompanying weight loss may serve as a maladaptive mechanism of emotion regulation by attenuating aversive emotional states in AN, thereby contributing to the maintenance of the disorder.
METHOD
Twenty-seven women with AN and 26 age-matched healthy women were shown short film-clips to elicit fear, sadness, amusement, and neutral emotional states. Eyeblink startle response was measured by electromyography in reaction to startle-eliciting acoustic stimuli presented 12 times binaurally during each film-clip.
RESULTS
As compared to healthy controls, patients with AN showed a blunted startle response to the fear- but not to the sadness-eliciting stimulus.
DISCUSSION
The findings support the assumption that underweight is associated with attenuated emotional reactivity to fear-eliciting material in AN. This is in line with the hypothesis that starvation and low body weight constitute a maladaptive mechanism of emotion regulation in AN, contributing to the maintenance of the disorder.
Topics: Adult; Anorexia Nervosa; Emotions; Female; Humans; Male; Reflex, Startle; Young Adult
PubMed: 30653688
DOI: 10.1002/eat.23022