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Copyright © 2020 the American Physiological Society. Express saccades are a manifestation of a visual grasp reflex triggered when visual information arrives in the intermediate layers of the superior colliculus (SCi), which in turn orchestrates the lower level brainstem saccade generator to evoke a saccade with a very short latency (~100 ms or less). A prominent theory regarding express saccades generation is that they are facilitated by preparatory signals, presumably from cortical areas, which prime the SCi before the arrival of visual information. Here, we test this theory by reversibly inactivating a key cortical input to the SCi, the frontal eye fields (FEF), while monkeys perform an oculomotor task that promotes express saccades. Across three tasks with a different combination of potential target locations and unilateral or bilateral FEF inactivation, we found a spared ability for monkeys to generate express saccades, despite decreases in express saccade frequency during FEF inactivation. This result is consistent with the FEF having a facilitatory but not critical role in express saccade generation, likely because other cortical areas compensate for the loss of preparatory input to the SCi. However, we also found decreases in the accuracy and peak velocity of express saccades generated during FEF inactivation, which argues for an influence of the FEF on the saccadic burst generator even during express saccades. Overall, our results shed further light on the role of the FEF in the shortest-latency visually-guided eye movements. NEW & NOTEWORTHY Express saccades are the shortest-latency saccade. The frontal eye fields (FEF) are thought to promote express saccades by presetting the superior colliculus. Here, by reversibly inactivating the FEF either unilaterally or bilaterally via cortical cooling, we support this by showing that the FEF plays a facilitative but not critical role in express saccade generation. We also found that FEF inactivation lowered express saccade peak velocity, emphasizing a contribution of the FEF to express saccade kinematics.

Mixed alien hand syndrome is a rare disease reported in the literature. The mixed callosal–frontal variant of alien hand syndrome is associated with uncoordinated hand movements, and patients may present with an involuntary grasp reflex and intermanual conflict. There are few videos in the existing literature on the comparison of patients' condition before and after recovery of the symptoms of mixed alien hand syndrome. We presented the prognosis of mixed alien hand syndrome in the form of a video. In addition, we have included some videos on the comparison of the condition of patients before and after recovery of the symptoms of mixed alien hand syndrome. A 57-year-old woman presented with left-handed intermanual conflict and right-handed involuntary grasp reflex due to infarction of the frontal lobe and corpus callosum. She was diagnosed with a mixed callosal–frontal variant of alien hand syndrome. Her left hand counteracted the purposeful movements of the right hand. However, the intermanual conflict disappeared after 3 months of therapy, including drug treatment and verbal-cue rehabilitation, and she regained normal coordination of her hand movements. Her prognosis was good despite the large corpus callosum lesions. The uncoordinated hand movements of the patient affected her daily life and caused psychological problems. Initiating rehabilitation early was important and necessary for her to regain coordination. It is possible that the verbal-cue training method played an important role in the recovery of the patient. Therefore, this method of rehabilitation deserves consideration and can be adopted in larger cohort studies as we presented only a single case. The possible mechanisms behind the verbal-cue exercise require further studies, and this patient had a good prognosis despite severe corpus callosum injury, which may merit further investigation.

The emulation of human sensation, perception, and action processes has become a major challenge for bioinspired intelligent robotics, interactive human-machine interfacing, and advanced prosthetics. Reflex actions, enabled through reflex arcs, are important for human and higher animals to respond to stimuli from environment without the brain processing and survive the risks of nature. An artificial reflex arc system that emulates the functions of the reflex arc simplifies the complex circuit design needed for "central-control-only" processes and becomes a basic electronic component in an intelligent soft robotics system. An artificial somatic reflex arc that enables the actuation of electrochemical actuators in response to the stimulation of tactile pressures is reported. Only if the detected pressure by the pressure sensor is above the stimulus threshold, the metal-organic-framework-based threshold controlling unit (TCU) can be activated and triggers the electrochemical actuators to complete the motion. Such responding mechanism mimics the all-or-none law in the human nervous system. As a proof of concept, the artificial somatic reflex arc is successfully integrated into a robot to mimic the infant grasp reflex. This work provides a unique and simplifying strategy for developing intelligent soft robotics, next-generation human-machine interfaces, and neuroprosthetics. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) Accepted version

Objectives The aim of the present study is to explore inter-rater reliability of primitive signs in a group of patients assessed for dementia. Patients and methods 97 patients admitted to our University Hospital for cognitive impairment were enrolled in the study. The mean age was 73.04 ± 8.68 (53 females and 44 males). All patients were examined by two cognitive neurologists in a blind fashion. The grasp reflex, the snout reflex, the glabella tap reflex and the palmomental reflex were elicited according to the current literature. Moreover, we add a stretch reflexes (the masseter reflex) to our battery. Results The most frequent primitive reflex was the palmomental reflex followed by the glabella tap, snout, and grasp. The inter-rater reliability was measured for each primitive reflex: grasp reflex (0.884) have a strong correspondence; the glabella tap (0.556), the palmomental (0.516) and the snout reflex (0.445) have otherwise a weak correspondence. The masseter reflex reaches a moderate agreement (0.662). All the measurements reached statistical significance (p Conclusion The results of the study show weak to substantial agreement for primitive signs and the masseter reflex as expressed by the low-to-high kappa values.

Using a rehabilitation robot to activate motion intention and reflex response simultaneously is an effective approach to aiding recovery from paralysis caused by neurological disorders. Mechanical motions supported by conventional robots are, however, not enough to activate reflex. In this paper, we propose a grasp-training robot that can stimulate the grasp reflex of a paralyzed hand by pushing the hand onto an elastic bar while supporting the grasping movements. In addition to this feature, we discuss the robot design in relation to its usability and wearability for ease of use in clinical practice. Experimental results obtained from healthy subjects show that the proposed robot can support grasping in a way similar to the traditional range-of-motion exercise used by therapists for grasp rehabilitation. Combining this appropriate grasping-motion support and the mechanism for pushing the hand onto an elastic bar succeeds in activating the grasp reflex of a completely paralyzed patient in a clinical test that involves monitoring electromyography signals from the paralyzed hand.

Vertebrates lateralize many behaviours including social interactions. Social displays typically comprise multiple components, yet our understanding of how these are processed come from studies that typically examine responses to the dominant component or the complex signal as a whole. Here, we examine laterality in lizard responses to determine whether receivers separate the processing of motion and colour signal components in different brain hemispheres. In Psammophilus dorsalis, males display colours that dynamically change during courtship and aggressive interactions. We tested the visual grasp reflex of both sexes using robotic stimuli that mimicked two signal components: (1) multiple speeds of head-bobbing behaviour and (2) multiple colours. We find no laterality in response to different motion stimuli, indicating that motion similarly attracts attention from both visual fields across sexes. Notably, receivers showed left visual field dominance to colours, especially when males were exposed to “aggression-specific” colours and females to “courtship-specific” colours.

The grasp reflex is a distressing symptom but the need to treat or suppress it has rarely been discussed in the literature. We report the case of a 17-year-old man who had suffered cerebral infarction of the right putamen and temporal lobe 10 years previously. Forced grasping of the hemiparetic left upper limb was improved after a unique combined treatment. Botulinum toxin type A (BTX-A) was first injected into the left biceps, wrist flexor muscles, and finger flexor muscles. Forced grasping was reduced along with spasticity of the upper limb. In addition, repetitive facilitative exercise and object-related training were performed under low-amplitude continuous neuromuscular electrical stimulation. Since this 2-week treatment improved upper limb function, we compared brain activities, as measured by near-infrared spectroscopy during finger pinching, before and after the combined treatment. Brain activities in the ipsilesional sensorimotor cortex (SMC) and medial frontal cortex (MFC) during pinching under electrical stimulation after treatment were greater than those before. The results suggest that training under electrical stimulation after BTX-A treatment may modulate the activities of the ipsilesional SMC and MFC and lead to functional improvement of the affected upper limb with forced grasping.

Purpose: To review palmar grasp reflex in human infants regarding psychomotor development. Method: “Palmar grasp reflex” and “grasping reflex” were searched in scientific journals published between 2000 and 2016. Two groups were identified in newborns up to six months: (1) Palmar grasp reflex was studied as part of instruments of neuropsychomotor evaluation. (2) Palmar grasp reflex was taken as a dependent or independent variable. Results: Eighteen articles were selected. Four were excluded because of inappropriate methods. Concerning the fourteen remaining, teen were included in group 1 (A) and four in group 2 (B). Conclusions: Palmar grasp reflex may be part of different instruments used to evaluate clinical and developmental studies. It may be easily detected without a necessary environment. Its intensity may be used as an index for acquisition of motor skills and lateral differences may be associated with hand preference in adults.

A distributed network of cortical and subcortical brain areas controls our oculomotor behavior. This network includes the superior colliculus (SC), which coordinates an ancient visual grasp reflex via outputs that ramify widely within the brainstem and spinal cord, accessing saccadic and other premotor and autonomic circuits. In this Review, we discuss recent results correlating subliminal SC activity in the absence of saccades with diverse components of the visual grasp reflex, including neck and limb muscle recruitment, pupil dilation, and microsaccade propensity. Such subtle manifestations of covert orienting are accessible in the motor periphery and may provide the next generation of oculomotor biomarkers in health and disease.

An 80-year-old woman had a stroke during treatment for diffuse large B cell lymphoma. She exhibited left hemispatial inattention, forced grasping with her left hand and moderate left hemiplegia. She always grasped the guard rail of the bed with her left hand, which prevented her from standing up and performing activities of daily living (ADL) centred on move and transfer operations. During a medical examination, she showed an imitation behaviour (IB), mimicking gestures visually presented by the examiner, such as holding up. By using her IB in rehabilitation training, flexor-dominated posture of the upper arm was gradually reduced and performance of ADL improved. Her brain lesion was localised in the right middle frontal gyrus. Based on our experience of concomitant appearance of forced grasping and IB in this case, the pathophysiological involvement of the lesion was discussed.

A male neonate weighing 4170 g (99th centile) was born to a non-diabetic primigravid woman by difficult vaginal delivery at 37 weeks gestation due to right shoulder dystocia. The labour was induced and Neville Barnes forceps were employed for successful delivery. Apart from maternal obesity (body mass index of 36 kg/m2), no other risk factors for fetal macrosomia or shoulder dystocia were noted. After birth, absent right shoulder movement with asymmetrical Moro reflex was noted, raising the possibility of right clavicular fracture with possible brachial plexus injury (BPI). Although left arm mobility was reduced, neurology was normal. Both elbows and wrists were flexed with symmetrical grasp reflex. A chest radiograph was performed, confirming displaced fractures of his right clavicle and left humerus (figure 1). Examination findings at 48 hours were unchanged, …

The grasp reflex is one of the primitive reflexes frequently observed in neurodegenerative diseases. However, quality of life and treatment of the grasp reflex are neglected in the literature. Following two brief case vignettes of patients seen recently who experienced disability from a grasp reflex, we briefly review its phenomenology, anatomy-physiology and epidemiology in neurodegenerative movement disorders, and assess the limited current literature regarding the quality of life and treatment.

Automatic prehensile responses are considered to form the reflex base for voluntary prehension. Aspects of upper limb dysfunction in cerebral palsy are identified as resulting from disorganization of this reflex base. Spastic forms often show exaggeration of traction and avoiding responses with a failure of higher level reactions. Athetoids exhibit a highly unstable equilibrium between the grasp reflex and avoiding response. Discussion in this article is based on a comprehensive literature review.

Objective: To describe 3 cases of patients with alcohol dependence whose primitive reflexes resolved upon initiation of acamprosate 666 mg 3 times daily. Case Summaries: A 57-year-old man had a long-standing history of alcohol dependence and a prominent snout reflex. The snout reflex resolved within 24 hours of starting treatment with acamprosate. A 45-year-old man with a long history of alcohol dependence had both a snout and a grasp reflex. These reflexes were present throughout 3 admissions for alcohol detoxification and continued until the end of his third admission, when he elected to begin treatment with acamprosate. Within 24 hours of starting treatment, the snout and grasp reflexes were absent. A 55-year-old man who drank heavily for 35 years presented with both a snout and a grasp reflex on admission. These persisted throughout his detoxification until the day after he had begun treatment with acamprosate. His primitive reflexes remained resolved through the next 4 days until discharge. All 3 of these patients remained on acamprosate at discharge. Discussion: Alcohol dependence is a common, debilitating disorder. One of the difficulties in treating alcohol dependence is its adverse effect on the brain, as higher aspects of cortical function necessary to maintain abstinence are eroded by alcohol. Acamprosate is a drug intended to help prevent relapse among patients with alcohol dependence. Unexpectedly, acamprosate may resolve primitive reflexes—a neurologic finding that suggests cognitive impairment—among patients with alcohol dependence. Conclusions: Acamprosate may relieve snout and grasp reflexes among patients with alcohol dependence.

The term "hypermetamorphosis" was originally coined in 1859 by an almost forgotten psychiatrist from Breslau, now Wroclaw in Poland, Heinrich Wilhelm Neumann. The 1906 textbook of his assistant Wernicke transmitted the concept to Kluver and Bucy, who understood it as the "excessive tendency to take notice of and to attend and react to every visual stimulus" in their syndrome description of bitemporal lobectomy in the monkey (1937-1939). Hypermetamorphosis so far has not been properly operationalized, and the concept appears outdated. Components such as "compulsive manipulation", "magnet reaction/groping", "compulsive grasping/grasp reflex", "utilization behavior", and "environmental dependency syndrome" can be better delineated and are commonly seen in frontal rather than temporal lesions. They may occur with frontal contusion, anterior cerebral artery infarction, in diseases of the Pick complex, and basal ganglia neurodegeneration.

This study investigated the somatic maturation and ontogeny of reflexes in neonate rats treated with sertraline (Sert) during the suckling period. The animals were divided into four groups; three that received daily doses of Sert (5, 10 or 15 mg/kg s.c.; groups Sert5, Sert10, and Sert15, respectively), and a fourth group that received distilled water (Dw) (1 ml/kg/b.w.). Growth indicators (body weight, axis of the head and tail length) were measured daily, from the 1st to the 21st postnatal day. The reflexes (righting, free-fall righting, negative geotaxis, cliff avoidance, auditory startle response, vibrissa placing and palm grasp) and physical-feature maturation (ear unfolding, auditory conduit opening, irruption of the lower incisors and eye opening) were recorded each day of the animal's life. All groups were compared to the Dw group. The body weight gain was reduced in all the Sert groups. Moreover, a delay in the growth of the body length was observed in all the Sert groups. Higher Sert doses reduced the speed of growth in the tail length. The medio-lateral head axis reduced in Sert15 and Sert5 doses. Otherwise, Sert10 had a temporary acceleration in this growth, but the growth of the anteroposterior head axis had a delay in all the Sert groups. The highest doses induced a delay in physical-feature maturation. The palm grasp reflex (disappearance) was retarded in Sert10; cliff avoidance advanced in Sert10; negative-geotaxis and free-fall righting retarded in Sert15. The findings suggest that altered serotonergic system activity induced by sertraline early in life could play a role in the retardation of the somatic growth ontogeny as well as a delay in the maturation of some reflexes.

Background: Developmental testing in children is concerned mainly with a pass or fail on tasks such as grasping, manipulating and inserting. Knowledge about the qualitative development of hand movements in young children is scarce. Aim: We studied the qualitative development of manipulative hand movements in 14-, 18- and 25-month-olds. Study design and subjects: Twenty-six children were videoed during grasping, manipulating and inserting cubes into a cup or box and pegs into a peg-board. Results: We found clear-cut, object-related results. The right hand was used mainly to grasp, manipulate and insert the pegs, while no hand preference was found for the cube. Generally, the quality of grasping and inserting did not change with age. At 18 months, the performance was more optimal if the children used pegs rather than cubes. The adjustment of hand opening became more adapted with increasing age when grasping the cubes; this was not observed for the pegs. Associated movements occurred less during pegging than while playing with the cubes. A variety of patterns were used for pegging. Besides a difference in band preference between girls and boys, some patterns became more prominent with increasing age. The success rate increased with age but was independent of the pattern used. Conclusion: This study stresses the need of a clear understanding of the entire spectrum of normal motor development. This knowledge forms the basis on which abnormalities, even of such common movement patterns as grasping, manipulating and inserting, can be reliably diagnosed in neurologically impaired infants and children. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

We report a patient with callosal haemorrhage and no extracallosal involvement who developed a unique form of intermanual conflict. In the acute phase the patient showed a mild speech disturbance and right hemiparesis, and in her right hand, a grasp reflex and compulsive manipulation of tools, all attributable to transient frontal involvement. In the chronic phase there was intermanual conflict occasionally associated with the sensation of a second left hand. The patient also presented a sign consisting of compulsive, automatic execution of orders by one hand (the left or the right) when the patient was specifically asked to perform the movement with the other hand (the right or the left, respectively). There was no left-right confusion in this patient. We call this condition agonistic dyspraxia. In contrast with diagonistic dyspraxia, this consists of the agonistic behaviour of the other hand under conditions in which the hand that has been instructed to respond cannot execute the request.

In daily clinical practice we noticed that patients with intellectual impairment spontaneously flex the elbow within a few seconds of the forearm being manipulated during routine examination of spasticity of the muscles in the upper extremities. We termed this phenomenon elbow flexion response (EFR), and prospectively studied it in 229 patients who underwent in-hospital rehabilitation following brain damage. Evaluation of each patient included EFR, patient profile, ability to communicate, scores on three parameters from various intelligence tests, scores on seven parameters testing primitive reflexes, and scores on three parameters describing personality. We investigated for relationships among these parameters. Consequently, although EFR rarely have a statistical association with the varied profiles of patients, patients with bilateral lesion or bilateral paresis demonstrated significantly more marked EFR than those with unilateral lesion or unilateral paresis. Patients with involvement of the frontal lobe showed significantly more marked EFR than those without damage in this area. Elbow flexion responses occurred significantly more frequently in relation with lower scores on intelligence and occurred with significantly higher frequency in conjunction with the more marked appearance of conventional primitive reflexes. Therefore, we conclude that EFR have a strong association with intelligence and with the existence of frontal lobe lesion, and their mode of clinical presentation parallels that of primitive reflexes particularly that of the grasp reflex. We propose that EFR could be referred as a variation of the grasp reflex occurring in the more proximal or axial part of the body.

According to the Geschwind-Behan-Galaburda (GBG) hypothesis, prenatal testosterone (T) causes a slowing in the development of the left brain with a consequent compensatory growth in the right brain, creating a reverse organisation of the cerebral lateralisation. That is, left- and right-handedness might be associated with high and low prenatal T levels, respectively. To test this hypothesis, the relations of T levels (umbilical cord blood) to grasp-reflex strengths were studied in human neonates. Handedness was assessed by measuring the grasp-reflex strengths from the right and left hands in 10 trials from each hand alternatively. There were two handedness groups: right-handers (R-L significantly greater than zero) and left-handers (significantly smaller than zero). Contrary to the GBG model, the mean free T concentration was found to be significantly higher in right-handers than left-handers for males and females. There was no significant difference in the total T levels between right- and left-handers. Free T concentrations positively correlated with RL grasp-reflex strengths, i.e. right-handedness increased as T increased, and left-handedness increased as T decreased. Contrary to these positive correlations, T negatively correlated with the grasp-reflex strengths from the right and left hands. These results partly supported the GBG hypothesis for this spinal-motor-asymmetry model. Total T did not significantly correlate with grasp-reflex strengths. The results suggest that prenatal T may at least play a role in prenatal determination of spinal motor lateralisation, with a possible consequent upward regulation of cerebral lateralisation.

46歳，右利きの女性。脳出血後より，左手の失書，右手の病的把握反射，右手の物品の強迫的使用行為，左手優位の両手の観念運動失行が出現した。頭部MRI検査では，左側の前頭葉内側面から前部帯状回の一部および脳梁体～膨大部に及ぶ病変を認めた。 本例では，病的把握反射が補足運動野の損傷なしに出現した点が注目された。物品の強迫的使用行為は本例の意志に反して “物品を使用したい” という強迫的な意図が発生することにより惹起された。 われわれは前補足運動野の損傷を重視し，前補足運動野を介する神経経路，特に視床～運動野間の神経結合の途絶が病的把握反射および物品の強迫的使用行為に関与すると考察した。

A 16-day-old term female infant is brought to the pediatrician’s office with a 1-day history of increased “spitting up,” agitation, and irritability. Her neck and upper body appear “stiffer” than usual, but no seizure activity is noted. Her parents measured an axillary temperature of 100.9°F (38.3°C) at home; her rectal temperature in the clinic is 104.0°F (40.0°C). ### Prenatal History: ### Birth History: The infant is sent from the pediatrician’s office to the emergency department for further evaluation of her fever and fussiness. Some time later, clinicians note that she has downward deviation of the right eye. On physical examination at the emergency department, the baby is active and alert, responds to stimuli, and has a full, but not bulging, anterior fontanelle. The right eyelid appears to be droopy, with increased pupil size on the right that is minimally reactive from 4 mm to 3 mm. The left pupil exhibits normal reaction from 3 mm to 2 mm. The baby has good suck, positive grasp reflex, symmetric Moro reflex, and normal strength and tone of all extremities. Apple …

To investigate the relationship between the site of brain damage and characteristics of the pathological grasping phenomena, we examined different varieties of the reaction in a consecutive series of 28 patients with unilateral hemispheric damage due to stroke. Patients with a lesion relatively confined to the supplementary motor area (n = 4) constantly exhibited a grasp reflex, mainly in the hand contralateral to the lesion, but they never showed a groping reaction. By contrast, patients with damage primarily involving the anterior cingulate gyrus (n = 3) developed the groping reaction in the hand contralateral to the lesion, but they had only a very mild grasp reflex in that hand. Patients with damage involving both the supplementary motor area and the anterior cingulate gyrus (n = 12) showed the grasp reflex and groping reaction mainly in the hand contralateral to the lesion. Patients with damage to the medial parietal lobe (n = 2), those with damage to the lateral convexity of the hemisphere (n = 6), and a patient with damage confined to the corpus callosum did not exhibit such grasping phenomena. From these observations, we conclude that the grasp reflex is closely related to a lesion of the supplementary motor area, whereas the groping reaction is bound to a lesion of the anterior cingulate gyrus.

Since there is no theological explanation for high growth hormone (GH) concentrations in perinatal blood, GH concentrations from umbilical cord blood were studied in relation to body weight and head circumference (brain weight) in the human neonates. GH exhibited inverse correlations with body weight and head circumference in these subjects, which depended upon sex, familial sinistrality (FS), and grasp-reflex dominance. This implies that GH may adversely influence the brain/body development during perinatal development on the basis of a genetically predetermined brain organization. It was suggested that the lipolytic and anti-insulin GH effects may be responsible for its body-weight reducing effects; the anti-insulin GH actions may be responsible for its brain-weight reducing effects. As a result of these actions, GH may limit the brain/body development, to induce a balanced growth during perinatal period.

Objective: To review the clinical utility of blinking and the release reflexes, palmomental, glabellar, grasp, and snout, as an important part of the bedside neurological examination. Design: Articles published from 1966 to 1993 that addressed blinking or the release reflexes were identified by searching the MEDLINE database. Thirty-seven references provided clinically useful and applicable information. Results: There is controversy regarding the optimal method of clinical elicitation of these reflexes. The release reflexes are frequently seen as an incidental abnormality in the elderly. A positive grasp reflex, especially if asymmetrical, is sensitive but not specific for abnormal brain function. Lack of habituation is more important than the mere presence or absence of a reflex. The brainstem circuits involved in the regulation of blinking and the release reflexes are discussed, as are their abnormalities in a variety of clinical settings. Conclusion: Blinking and the release reflexes have clinical utility in the diagnosis and bedside clinical assessment of diseases as diverse as frontal lobe lesions, hydrocephalus, multiple sclerosis, Parkinson's disease, Alzheimer's disease and other dementias, falls in the elderly, ageing, HIV-encephalopathy, schizophrenia, tumors in the region of the sylvian aqueduct and recovery from head trauma.

The relations of the grasp-reflex strengths from right (R) and left (L) hands to human growth hormone (hGH) levels were studied in human neonates within the first day after birth. In right-handed (RH) males without familial sinistrality (-FS), grasp reflex from right and left hands directly correlated with hGH. In RH, -FS females, grasp reflex from right and left hands inversely correlated with hGH. In -FS, LH males, grasp reflex from right and left inversely correlated with hGH (no significant correlations in LH, -FS females). The R-L grasp reflex decreased linearly with hGH, only in RH, -FS males. These results indicated that hGH may affect cerebral development according to genetically predetermined neural patterns in utero.

Background: A new clinical entity of ingrowing fingernail of infants, which was associated with the grasp reflex, was found. Objective: To define this new disease. Methods: We encountered 26 cases of this disease between 1984 and 1996. We describe the clinical features of this new disease. Results: The median age of the cases was 1 month (from 6 days to 4 months). The main findings were multiple and bilateral paronychia of the fingernails. This disease was observed in some babies only when they had the grasp reflex. Conclusions: The repeated compression of the nail due to the grasp reflex caused the soft tissue swelling at the end of the nail to be penetrated by the edge of the nail plate.

Usage of the term "alien hand sign" is reviewed in 20 published cases. It refers to apparently purposeful, upper-extremity movements that the patient reports are beyond his/her control. Lesions were found in medial frontal cortex and/or the corpus callosum with presentation being unilateral and transient, unless bilateral cortical and subcortical structures were involved. There was a high co-occurrence of speech hesitation, limb dyspraxia, tactile dysnomia, muscle weakness, and grasp reflex on the alien side. Five behavioral manifestations of alien movement have been described, with grasping movements and intermanual conflict being the most common. Two manifestations, exaggerated ataxic automatisms and drifting movements, likely represent other types of movement disorders. Dysfunction of the supplementary motor area and related structures has been implicated, but the exact causal mechanism remains uncertain.

Four patients are described who presented with a paroxysmal form of the alien hand syndrome. Two patients with damage to one frontomedial cortex had brief episodes of abnormal motor behaviour of the contralateral arm that featured groping, grasping, and apparently purposeful but perseverative movements, which both patients interpreted as alien or foreign. The other two patients, with posterior parietal damage, reported a paroxysmal feeling of unawareness of the location of the contralateral arm, lack of recognition of the arm as their own, purposeless movements, and personification of the arm. These cases represent a new form of the alien hand syndrome manifested by brief, paroxysmal episodes, which may be due to ictal mechanisms.

Grasp reflex and its asymmetry was studied in relation to pH of the umbilical blood in human newborns, to examine whether the degree of acidity in fetal blood (birth stress) is associated with cerebral laterality. Low pH values were considered as an index for birth stress. Grasp-reflex strength was found to be directly related to pH in total sample. There were sex-related differences. Namely, this correlation was true only for female newborns, not for males. Right minus left grasp-reflex strength linearly increased with pH, i.e., low pH values were associated with left-hand dominance, but only in males. The grasp-reflex asymmetry was not related to pH in females. It was concluded that blood pH may be associated with motor asymmetry and motor development in human newborns, but show sex-related differences; female brain seemed to be more sensitive to pH changes than male brain. The results partly supported the Bakan's hypothesis that birth stress may be associated with left-handedness.

The ability to sense and respond to frictional variations is important for dexterous manipulation. It is demonstrated that it is possible to elicit rapid, nonhabituating and sustained grasp responses by means of a tactile display. Experiments in which subjects grasped and lifted an instrumented test object using the thumb and index finger are reported. While the object was held in air, rapid but small sliding movements were invoked between the object and either contact plate and caused a load force redistribution. This reliably triggered a grasp force increase similar to the ones elicited by natural slips occurring during normal manipulation. An important application of this finding is in relaying frictional information from a slave hand to a human operator. Furthermore, it may make it possible to reduce disparity between master and slave hands in force reflective telemanipulation systems. >

Here we present an economical and versatile platform for developing motor control and sensory feedback of a prosthetic hand via in vitro mammalian peripheral nerve activity. In this study, closed-loop control of the grasp function of the prosthetic hand was achieved by stimulation of a peripheral nerve preparation in response to slip sensor data from a robotic hand, forming a rudimentary reflex action. The single degree of freedom grasp was triggered by single unit activity from motor and sensory fibers as a result of stimulation. The work presented here provides a novel, reproducible, economic, and robust platform for experimenting with neural control of prosthetic devices before attempting in vivo implementation.

Individuals who have undergone hemispherectomy for treatment of intractable epilepsy offer a rare and valuable opportunity to examine the ability of a single cortical hemisphere to control oculomotor performance. We used peripheral auditory events to trigger saccades, thereby circumventing dense postsurgical hemianopia. In an antisaccade task, patients generated numerous unintended short-latency saccades toward contralesional auditory events, indicating pronounced limitations in the ability of a single hemicortex to exert normal inhibitory control over ipsilateral (i.e., contralesional) reflexive saccade generation. Despite reflexive errors, patients retained an ability to generate correct antisaccades in both directions. The prosaccade task revealed numerous contralesional express saccades, a robust contralesional gap effect, but the absence of both effects for ipsilesional saccades. These results indicate limits to the saccadic control capabilities following hemispherectomy: A single hemicortex can mediate antisaccades in both directions, but plasticity does not extend fully to the bilateral inhibition of reflexive saccades. We posit that these effects are due to altered control dynamics that reduce the responsivity of the superior colliculus on the intact side and facilitate the release of an auditory-evoked ocular grasp reflex into the blind hemifield that the intact hemicortex has difficulty suppressing.

The grasp reflex and related prehensile phenomena were investigated in two studies. In Study 1, 491 patients consecutively admitted to the neurological wards of our department were tested with a standardized procedure. Grasping was found in 8% of brain-damaged patients and occurred predominantly in patients with single (14 cases) or multiple (10 cases) hemispheric lesions, accompanied by stable neurological symptoms. The locus of the lesion was either in the frontal lobe or in the deep nuclei and subcortical white matter. Grasping never occurred when the disease was confined to the retrorolandic regions. Study 2 was designed to identify the frontal structures responsible for grasping. Forty-four patients who either showed grasping or had CT scan documentation of frontal damage were investigated. Grasping was found in 70% of patients who had involvement of the medial areas and was always associated with damage to the cingulate gyrus; the supplementary motor cortex was less consistently encroached upon. It also occurred following damage to the lateral motor and premotor areas, but only in 26% of cases. A few patients with grasping had deep lesions. The clinical analysis of the symptom showed that it usually affected both hands, even when the lesion was unilateral, and that in most patients it did not manifest itself as a forced phenomenon, but could be modified by will, although it showed up again as soon as the patient's attention was diverted. Groping was more rarely found and the so-called grasp reaction was unusual. No hemispheric asymmetry in the occurrence of this set of phenomena was apparent.

The strength of the grasp reflex from the right and left hands was estimated in male and female newborns within the second day after birth. In the total sample (N = 121), the mean strength of the grasp reflex from the right hand was found to be significantly higher than that from the left hand. There was a significant positive linear correlation between reflex strengths from the right and left hands. The mean right minus left (R - L) reflex strength was found to be significantly larger than zero. There was a positive linear relationship between the R-L reflex strength and the reflex strengths from the right and left hands. This was more pronounced for the right hand than the left hand. The reflex strengths from the right and left hands were found to be positively linearly correlated with the weight of the newborn babies. These results indicated a grasp reflex lateralization in newborns. The right-bias in the grasp-reflex asymmetry established in this work would create a basis for the development of the right-hand preference in adulthood.

The grasp reflex was studied in human newborn without familial sinistrality. Of 60 females, 26 (43.3%) were right-handed and 34 (56.7%) ambidextrous. Of 62 males, 20 (32.3%) were right-handed, 39 (62.9%) ambidextrous, and 3 (4.8%) left-handed. There was a nonsignificant preponderance of right-dominance in females and a significant preponderance of nonright-handedness in males. In right-handers, the mean right minus left (R-L) grasp-reflex showed a positive linear correlation with the grasp-reflex from the right and left hands, with a higher correlation for the right hand. In ambidexters, the R-L grasp reflex did not show any significant correlation with the grasp reflex from the right and left hands. The mean grasp-reflex from right and left were found to be significantly smaller in ambidextrous males and females then right-handed males and females, with a much higher significance for the right hand. It was concluded that females tended to have a more pronounced reflex lateralization than males. The results also indicated that the left brain may be more important than the right brain for the development of a spinocerebral motor lateralization in humans.

The lateralization of the grasp reflex was studied in male and female newborns. The mean grasp-reflex strength of the right hand was found to be higher than that of the left hand in males, but the difference was not significant. The mean grasp-reflex strength of the right hand was found to be significantly higher than that of the left hand in females. There was no significant difference between the mean grasp-reflex strengths of the right hand in the male and female subjects. The mean reflex strength of the left hand was found to be higher in males than females; the difference was only marginally significant. The right minus left (R - L) reflex strength showed a significant positive linear relation to the right-and left-reflex strengths in both sexes. This was, however, much more pronounced for the right-reflex than the left-reflex. There was a significantly positive linear correlation between the reflex strengths of the right and left hands and the body weight in males. The females did not show such a relationship between reflex strength and body weight. These sex-related differences in the grasp reflex in newborns were discussed in light of cerebral lateralization and its hormonal modulation.