scholarly journals A geometric model of defensive peripersonal space

2016 ◽  
Vol 115 (1) ◽  
pp. 218-225 ◽  
Author(s):  
R. J. Bufacchi ◽  
M. Liang ◽  
L. D. Griffin ◽  
G. D. Iannetti
Keyword(s):  
Goodness Of Fit ◽  
Geometric Model ◽  
Peripersonal Space ◽  
Blink Reflex ◽  
The Body ◽  
Hand Position ◽  
Body Area ◽  
Empirical Observation ◽  
Spatial Features ◽  
The Face

Potentially harmful stimuli occurring within the defensive peripersonal space (DPPS), a protective area surrounding the body, elicit stronger defensive reactions. The spatial features of the DPPS are poorly defined and limited to descriptive estimates of its extent along a single dimension. Here we postulated a family of geometric models of the DPPS, to address two important questions with respect to its spatial features: What is its fine-grained topography? How does the nervous system represent the body area to be defended? As a measure of the DPPS, we used the strength of the defensive blink reflex elicited by electrical stimulation of the hand (hand-blink reflex, HBR), which is reliably modulated by the position of the stimulated hand in egocentric coordinates. We tested the goodness of fit of the postulated models to HBR data from six experiments in which we systematically explored the HBR modulation by hand position in both head-centered and body-centered coordinates. The best-fitting model indicated that 1) the nervous system's representation of the body area defended by the HBR can be approximated by a half-ellipsoid centered on the face and 2) the DPPS extending from this area has the shape of a bubble elongated along the vertical axis. Finally, the empirical observation that the HBR is modulated by hand position in head-centered coordinates indicates that the DPPS is anchored to the face. The modeling approach described in this article can be generalized to describe the spatial modulation of any defensive response.

Defensive peripersonal space: the blink reflex evoked by hand stimulation is increased when the hand is near the face

2012 ◽  
Vol 107 (3) ◽  
pp. 880-889 ◽  
Author(s):  
C. F. Sambo ◽  
M. Liang ◽  
G. Cruccu ◽  
G. D. Iannetti
Keyword(s):  
Electrical Stimulation ◽  
Brain Stem ◽  
Median Nerve ◽  
Safety Margin ◽  
Peripersonal Space ◽  
Blink Reflex ◽  
Hand Position ◽  
Electromyographic Activity ◽  
The Face ◽  
Stimulation Of

Electrical stimulation of the median nerve at the wrist may elicit a blink reflex [hand blink reflex (HBR)] mediated by a neural circuit at brain stem level. As, in a Sherringtonian sense, the blink reflex is a defensive response, in a series of experiments we tested, in healthy volunteers, whether and how the HBR is modulated by the proximity of the stimulated hand to the face. Electromyographic activity was recorded from the orbicularis oculi, bilaterally. We observed that the HBR is enhanced when the stimulated hand is inside the peripersonal space of the face, compared with when it is outside, irrespective of whether the proximity of the hand to the face is manipulated by changing the position of the arm ( experiment 1) or by rotating the head while keeping the arm position constant ( experiment 3). Experiment 2 showed that such HBR enhancement has similar magnitude when the participants have their eyes closed. Experiments 4 and 5 showed, respectively, that the blink reflex elicited by the electrical stimulation of the supraorbital nerve, as well as the N20 wave of the somatosensory evoked potentials elicited by the median nerve stimulation, are entirely unaffected by hand position. Taken together, our results provide compelling evidence that the brain stem circuits mediating the HBR in humans undergo tonic and selective top-down modulation from higher order cortical areas responsible for encoding the location of somatosensory stimuli in external space coordinates. These findings support the existence of a “defensive” peripersonal space, representing a safety margin advantageous for survival.

scholarly journals Modulation of exteroceptive electromyographic responses in defensive peripersonal space

2019 ◽  
Vol 121 (4) ◽  
pp. 1111-1124 ◽  
Author(s):  
Viviana Versace ◽  
Stefania Campostrini ◽  
Luca Sebastianelli ◽  
Leopold Saltuari ◽  
Markus Kofler
Keyword(s):  
Silent Period ◽  
Peripersonal Space ◽  
Blink Reflex ◽  
The Body ◽  
Electromyographic Activity ◽  
Sensory Afferents ◽  
Eyes Closed ◽  
Cutaneous Silent Period ◽  
The Face ◽  
Long Loop Reflex

The cutaneous silent period (CSP) to noxious finger stimulation constitutes a robust spinal inhibitory reflex that protects the hand from injury. In certain conditions, spinal inhibition is interrupted by a brief burst-like electromyographic activity, dividing the CSP into two inhibitory phases (I1 and I2). This excitatory component is termed long-loop reflex (LLR) and is presumed to be transcortical in origin. Efficient defense from environmental threats requires sensorimotor integration between multimodal sensory afferents and planning of defensive movements. In the defensive peripersonal space (DPPS) immediately surrounding the body, we interact with objects and persons with increased alertness. We investigated whether CSP differs when the stimulated hand is in the DPPS of the face compared with a distant position. Furthermore, we investigated the possible role of vision in CSP modulation. Fifteen healthy volunteers underwent CSP testing with the handheld either within 5 cm from the nose (near) or away from the body (far). Recordings were obtained from first dorsal interosseous muscle following index (D2) or little finger (D5) stimulation with varying intensities. A subgroup of subjects underwent CSP recordings in near and far conditions, both with eyes open and with eyes closed. No inhibitory CSP parameter differed between stimulation in near and far conditions. LLRs occurring following D2 stimulation were significantly larger in near than far conditions at all stimulus intensities, irrespective of subjects seeing their hand. Similar to the hand-blink reflex, spinally organized protective reflexes may be modulated by corticospinal facilitatory input when the hand enters the DPPS of the face. NEW & NOTEWORTHY The present findings demonstrate for the first time that a spinally organized protective reflex, the cutaneous silent period (CSP), may be modulated by top-down corticospinal facilitatory input when the stimulated hand enters the defensive peripersonal space (DPPS) of the face. In particular, the cortically mediated excitatory long-loop reflex, which may interrupt the CSP, is facilitated when the stimulated hand is in the DPPS, irrespective of visual control over the hand. No spinal inhibitory CSP parameter differs significantly in or outside the DPPS.

scholarly journals Patterns of multisensory facilitation distinguish peripersonal from reaching space

2020 ◽  
Author(s):  
A. Zanini ◽  
I. Patané ◽  
E. Blini ◽  
R. Salemme ◽  
E. Koun ◽  
...  
Keyword(s):  
Receptive Fields ◽  
Theoretical Models ◽  
Body Part ◽  
Peripersonal Space ◽  
The Body ◽  
Theoretical Issue ◽  
Hand Position ◽  
Body Parts ◽  
Arm Reaching ◽  
Whole Space

AbstractPeripersonal space is a multisensory representation of the space near body parts facilitating interactions with the close environment. Studies on non-human and human primates converge in showing that peripersonal space (PPS) is a body-part-centred representation that guides actions. Because of these characteristics, growing confusion conflates peripersonal and arm-reaching space (ARS) that is the space one’s arm can reach. Despite neuroanatomical evidence favors their distinction, whether PPS and ARS tap into different spatial representations remains poorly understood. Here, in five experiments we found that PPS differs from ARS in male and female human participants (N = 120), as evidenced both by their performance and the modeling of their multisensory facilitation. We mapped multisensory facilitation in detecting touches at the hand, placed in different locations radially within ARS. Results showed that 1) PPS is smaller than ARS; 2) multivariate modeling of spatial patterns of multisensory facilitation predicts well the position of the participants’ hand within ARS; 3) multisensory facilitation maps shift according to changes of hand position, revealing hand-centred coding of PPS, but not ARS; and 4) cross-correlation analyses highlight isomorphic multisensory facilitation maps across hand positions, suggesting their functional similarity to the receptive fields of monkeys’ multisensory neurons. In sharp contrast, ARS mapping produced undistinguishable patterns across hand positions, cross-validating the conclusion that PPS and ARS are distinct. These findings call for a refinement of theoretical models of PPS and ARS, which are relevant in constructs as diverse as action and self representation, (social) interpersonal distance, brain-machine interfaces and neuroprosthetics.Significance StatementThe peripersonal space (PPS) is a multisensory interface allowing us to interact with objects in the space close to our body-parts, playing a fundamental role for the defense of the body and for the motor control of actions. Recent research has conflated PPS with the arm-reaching space (ARS), that is whole space reachable by the arm. However, there is actually no evidence supporting this equivalence and the anatomical and functional differences between PPS and ARS have been largely overlooked. In this paper, we frame the theoretical issue in depth, validate a novel methodological paradigm across five experiments, and eventually report robust and cross-validated evidence for the distinction between PPS and ARS, supported by both multivariate and univariate analyses.

scholarly journals Transcutaneous trigeminal nerve stimulation modulates the hand blink reflex

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Beniamina Mercante ◽  
Nicola Loi ◽  
Francesca Ginatempo ◽  
Monica Biggio ◽  
Andrea Manca ◽  
...  
Keyword(s):  
Median Nerve ◽  
Trigeminal Nerve ◽  
Nerve Stimulation ◽  
Blink Reflex ◽  
Infraorbital Nerve ◽  
Hand Position ◽  
Median Nerve Stimulation ◽  
Trigeminal Nerve Stimulation ◽  
Before And After ◽  
The Face

AbstractThe hand-blink reflex (HBR) is a subcortical response, elicited by the electrical stimulation of the median nerve, whose magnitude is specifically modulated according to the spatial properties of the defensive peripersonal space (DPPS) of the face. For these reasons, the HBR is commonly used as a model to assess the DPPS of the face. Little is known on the effects induced by the activation of cutaneous afferents from the face on the DPPS of the face. Therefore, we tested the effect of non-painful transcutaneous trigeminal nerve stimulation (TNS) on the amplitude of the HBR. Fifteen healthy participants underwent HBR recording before and after 20 min of sham- and real-TNS delivered bilaterally to the infraorbital nerve in two separate sessions. The HBR was recorded bilaterally from the orbicularis oculi muscles, following non-painful median nerve stimulation at the wrist. The HBR amplitude was assessed in the “hand‐far” and “hand‐near” conditions, relative to the hand position in respect to the face. The amplitudes of the hand-far and hand-near HBR were measured bilaterally before and after sham- and real-TNS. Real-TNS significantly reduced the magnitude of the HBR, while sham-TNS had no significant effect. The inhibitory effect of TNS was of similar extent on both the hand-far and hand-near components of the HBR, which suggests an action exerted mainly at brainstem level.

scholarly journals Profil pitiriasis versikolor di Poliklinik Kulit dan Kelamin RSUP Prof. Dr. R. D. Kandou Manado periode Januari-Desember 2013

e-CliniC ◽  
2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Dwi Y.F. Isa ◽  
Nurdjannah J. Niode ◽  
Herry E.J. Pandaleke
Keyword(s):  
Antifungal Therapy ◽  
Age Groups ◽  
Descriptive Study ◽  
Fungal Disease ◽  
Pityriasis Versicolor ◽  
The Body ◽  
Body Area ◽  
Lesion Location ◽  
The Face

Abstract: Pityriasis versicolor is a chronic superficial fungal disease caused by Malasezzia furfur. Pityriasis versicolor can infect the face, neck, trunk, upper arms, underarms, and groin. Pityriasis versicolor is characterized by scaly patches of fine white or dark, irregular to regular shapes, and clear to diffuse limits. However, pityriasis versicolor is generally asymptomatic, therefore, commonly people do not realize that they are infected by that fungi. This study aimed to determine the profile of pityriasis versicolor at Dermatovenereology clinic of Prof. Dr. R. D. Kandou Hospital from January to December 2013. This was a retrospective descriptive study based on the number of cases, sex, age, occupation, color of lesion, location of lesion, and type of treatment. The results showed that there were 36 cases of pityriasis versicolor, mostly were males (58.3%), age groups 15-24 years and 25-44 years (30.6%), and private workers (27.8 %). Most lesions were hypopigmentation (80.6%), located on the body area and the combination of the face, trunk, and extremities (38.9%). The most commonly prescribed treatment was topical antifungal therapy (77.8%). Keywords: pityriasis versicolor Abstrak: Pitiriasis versikolor merupakan penyakit jamur superfisial kronik yang disebabkan oleh Malasezzia furfur. Pitiriasis versikolor dapat menginfeksi wajah, leher, badan, lengan atas, ketiak, dan lipat paha. Pitiriasis versikolor ditandai dengan adanya bercak-bercak bersisik halus berwarna putih atau gelap, bentuk tidak teratur sampai teratur, dan batas jelas sampai difus. Umumnya gejala pitiriasis versikolor asimtomatik sehingga terkadang penderita tidak menyadari telah terinfeksi penyakit tersebut. Penelitian ini bertujuan untuk mengetahui profil pitiriasis versikolor di Poliklinik Kulit dan Kelamin RSUP Prof. Dr. R. D. Kandou periode Januari-Desember 2013. Jenis penelitian ini ialah deskriptif retrospektif berdasarkan jumlah kasus, jenis kelamin, umur, pekerjaan, warna lesi, lokasi lesi, dan jenis pengobatan. Hasil penelitian mendapatkan 36 kasus pitiriasis versikolor, terbanyak pada laki-laki (58,3%), kelompok usia 15-24 tahun dan 25-44 tahun (30,6%), dan pekerja swasta (27,8%). Lesi hipopigmentasi paling banyak ditemukan (80,6%) dengan lokasi lesi pada daerah badan dan kombinasi antara wajah, badan, ekstremitas (38,9%). Pengobatan yang paling sering diberikan ialah terapi antijamur topikal (77,8%).Kata kunci: pitiriasis versikolor

scholarly journals Approaching threatening stimuli cause an expansion of defensive peripersonal space

2017 ◽  
Vol 118 (4) ◽  
pp. 1927-1930 ◽  
Author(s):  
R. J. Bufacchi
Keyword(s):  
Continuous Monitoring ◽  
Peripersonal Space ◽  
Blink Reflex ◽  
The Body ◽  
Environmental Threats ◽  
Environmental Stimuli ◽  
Defensive Responses ◽  
Threatening Stimulus ◽  
Threatening Stimuli

When sudden environmental stimuli signaling threat occur in the portion of space surrounding the body (defensive peripersonal space), defensive responses are enhanced. Recently Bisio et al. (Bisio A, Garbarini F, Biggio M, Fossataro C, Ruggeri P, Bove M. J Neurosci 37: 2415–2424, 2017) showed that a marker of defensive peripersonal space, the defensive hand-blink reflex, is modulated by the motion of the eliciting threatening stimulus. These results can be parsimoniously explained by the continuous monitoring of environmental threats, resulting in an expansion of defensive peripersonal space when threatening stimuli approach.

Individual Differences in the Flexibility of Peripersonal Space

2017 ◽  
Vol 64 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Samuel B. Hunley ◽  
Arwen M. Marker ◽  
Stella F. Lourenco
Keyword(s):  
Individual Differences ◽  
Peripersonal Space ◽  
The Body ◽  
Laser Pointer ◽  
Baseline Measure ◽  
Bisection Task ◽  
Defensive Function ◽  
Representational Space ◽  
Laser Condition ◽  
Line Bisection Task

Abstract. The current study investigated individual differences in the flexibility of peripersonal space (i.e., representational space near the body), specifically in relation to trait claustrophobic fear (i.e., fear of suffocating or being physically restricted). Participants completed a line bisection task with either a laser pointer (Laser condition), allowing for a baseline measure of the size of one’s peripersonal space, or a stick (Stick condition), which produces expansion of one’s peripersonal space. Our results revealed that individuals high in claustrophobic fear had larger peripersonal spaces than those lower in claustrophobic fear, replicating previous research. We also found that, whereas individuals low in claustrophobic fear demonstrated the expected expansion of peripersonal space in the Stick condition, individuals high in claustrophobic fear showed less expansion, suggesting decreased flexibility. We discuss these findings in relation to the defensive function of peripersonal space and reduced attentional flexibility associated with trait anxieties.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

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