Somatosensory & Motor Research (Somatosens Mot Res)

Publications in this journal

• Article: Null mutations of NT-3 and Bax affect trigeminal ganglion cell number but not brainstem barrelette pattern formation.

  Tony Mosconi, J J Arends, Mark F Jacquin
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  ABSTRACT: Abstract Trigeminal ganglion (TG) neurons innervate the grid-like array of whisker follicles on the face of the mouse. Central TG axons project to the trigeminal (V) brainstem nuclear complex, including the nucleus principalis (PrV) and the spinal subnucleus interpolaris (SpVi), where they innervate barrelettes that are organized in a pattern that recapitulates the whisker pattern on the face. Neurotrophin-3 (NT-3) supports a population of TG cells that supply slowly adapting mechanoreceptors in the whisker pad. We examined mice at embryonic day 17 (E17) and on the day of birth (P0) with null mutations of NT-3, Bax, a proapoptotic gene associated with naturally occurring cell death, and Bax/NT-3 double knockout (KO) mutants to determine if: (1) the number of TG cells would be reduced; (2) eliminating the Bax gene would rescue the NT-3-dependent neurons; and (3) the central projections of the rescued axons in the Bax/NT-3 double KO mice would fail to develop the barrelette patterns in the PrV and SpVi subnuclei. In mice at E17, NT-3(-/-) mutants had 65% fewer TG neurons than found in age-matched wild-type (WT) mice, and at P0, the number was reduced by 55% (p < 0.001 for both). Bax null mutant mice at E17 had 132% of the WT number of TG cells (p < 0.001), although the numbers returned to WT levels by P0. Bax/NT-3 double KO mice at E17 had TG cell numbers equal to those seen in WT, but the double KO failed to retain WT TG neuron numbers in P0 mice (39% fewer cells; p < 0.001). In all cases of reduced experimental neuron numbers, and in the E17 Bax(-/-) mice with supernumerary cells, the barrelette patterns in the PrV and SpVi were normal. Only a slight qualitative reduction in overall barrelette field area and clarity of barrelettes were seen. These results suggest that NT-3 is not necessary for barrelette pattern formation in the brainstem.
  Somatosensory & Motor Research 04/2013;
• Article: Neural response to movement of the hand and mouth in the secondary somatosensory cortex of Japanese monkeys during a simple feeding task.

  Miki Taoka, Michio Tanaka, Sayaka Hihara, Hisayuki Ojima, Atsushi Iriki
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  ABSTRACT: Abstract Neural activity was recorded in the secondary somatosensory cortex (SII) of macaque monkeys during a simple feeding task. Around the border between the representations of the hand and face in SII, we found neurons that became active during both retrieving with the hand and eating; 59% had receptive fields (RFs) in the hand/face and the remaining 41% had no RFs. Neurons that responded to touching objects were rarely found. This suggests their sensorimotor function rather than tactile object recognition.
  Somatosensory & Motor Research 04/2013;
• Article: Comparison of cortical activation patterns by somatosensory stimulation on the palm and dorsum of the hand.

  Sung Ho Jang, Jeong Pyo Seo, Sang Ho Ahn, Mi Young Lee
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  ABSTRACT: Abstract Objectives: Little is known about differences of cortical activation according to body location. We attempted to compare brain activation patterns by somatosensory stimulation on the palm and dorsum of the hand, using functional magnetic resonance imaging (fMRI). Method: We recruited 15 healthy right-handed volunteers for this study. fMRI was performed during touch stimulation using a rubber brush on an area of the same size on the palm or dorsum of the hand. Regions of interest (ROIs) were drawn at the primary sensory-motor cortex (SM1), posterior parietal cortex, and secondary somatosensory cortex. Results: Group analysis of fMRI data indicated that touch stimulation on the palm resulted in production of more activated voxels in the contralateral SM1 and posterior parietal cortex than on the dorsum of the hand. The most activated ROI was found to be the contralateral SM1 by stimulation of the palm or dorsum, and the number of activated voxels (5875) of SM1 by palm stimulation was more than 2 times that (2282) of dorsum stimulation. The peak activated value in the SM1 by palm stimulation (16.43) was also higher than that of the dorsum (5.52). Conclusion: We found that stimulation of the palm resulted in more cortical activation in the contralateral SM1 than stimulation of the dorsum. Our results suggested that the palm of the hand might have larger somatotopy of somatosensory representation for touch in the cerebral cortex than the dorsum of the hand. Our results would be useful as a rehabilitation strategy when more or less somatosensory stimulation of the hand is necessary.
  Somatosensory & Motor Research 04/2013;
• Article: Independent effects of endogenous and exogenous attention in touch.

  Alexander Jones, Bettina Forster
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  ABSTRACT: Abstract Endogenous and exogenous attention in touch have typically been investigated separately. Here we use a double-cueing paradigm manipulating both types of orienting in each trial. Bilateral endogenous cues induced long-lasting facilitation of endogenous attention up to 2 s. However, the exogenous cue only elicited an effect at short intervals. Our results favour a supramodal account of attention and this study provides new insight into how endogenous and exogenous attention operates in the tactile modality.
  Somatosensory & Motor Research 04/2013;
• Article: Are there changes in postural regulation across the lifespan?

  René Schwesig, David Fischer, Alexander Kluttig
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  ABSTRACT: Abstract The purpose was to obtain parameters of postural regulation (n = 1724) of asymptomatic subjects (6-97 years). The maximum postural stability and capacity of postural subsystems were calculated for the age ranges from 34 to 35 years (men) and from 38 to 44 years (women). A significant decline in postural performance was observed in the 40s (men) and 50s (women). Data can be used in the evaluation of dizziness and balance disorders in people of all ages.
  Somatosensory & Motor Research 04/2013;
• Article: Different motor learning effects on excitability changes of motor cortex in muscle contraction state.

  Kenichi Sugawara, Shigeo Tanabe, Tomotaka Suzuki, Toshio Higashi
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  ABSTRACT: Abstract We aimed to investigate whether motor learning induces different excitability changes in the human motor cortex (M1) between two different muscle contraction states (before voluntary contraction [static] or during voluntary contraction [dynamic]). For the same, using motor evoked potentials (MEPs) obtained by transcranial magnetic stimulation (TMS), we compared excitability changes during these two states after pinch-grip motor skill learning. The participants performed a force output tracking task by pinch grip on a computer screen. TMS was applied prior to the pinch grip (static) and after initiation of voluntary contraction (dynamic). MEPs of the following muscles were recorded: first dorsal interosseous (FDI), thenar muscle (Thenar), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) muscles. During both the states, motor skill training led to significant improvement of motor performance. During the static state, MEPs of the FDI muscle were significantly facilitated after motor learning; however, during the dynamic state, MEPs of the FDI, Thenar, and FCR muscles were significantly decreased. Based on the results of this study, we concluded that excitability changes in the human M1 are differentially influenced during different voluntary contraction states (static and dynamic) after motor learning.
  Somatosensory & Motor Research 04/2013;
• Article: Brainstem excitability is not influenced by blood lactate levels.

  Marinella Coco, Giovanna Alagona, Valentina Perciavalle, Giuseppe Rapisarda, Erminio Costanzo, Vincenzo Perciavalle
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  ABSTRACT: The influence of blood lactate on brainstem excitability was tested by using the blink reflex (BR) recovery cycle on 18 sprinters. Blood lactate was measured before maximal cycling, at the end, as well as 5 and 10 min after the exhaustion. Blood lactate was associated with a decrement of R2 whereas only small changes were observed after an intravenous infusion of lactate. It seems, therefore, that lactate influences BR mainly by acting at the cortical level.
  Somatosensory & Motor Research 03/2013;
• Article: Change in EMG with skin friction at different frequencies during elbow flexion.

  Hitoshi Sugawara, Ryota Shimose, Chigaya Tadano, Nobuyuki Ushigome, Masuo Muro
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  ABSTRACT: Modulation of muscle activation in superficial and deeper regions may be induced by tactile stimulation. The purpose of this study was to examine changes in muscle activation with skin friction. Subjects performed an isometric elbow flexion at 30% maximal voluntary cotraction (MVC) with skin friction at different frequencies (0.5-2.7 Hz). Surface electromyography (S-EMG) and intramuscular EMG were obtained from the elbow flexor muscles (BBS: short head of biceps brachii, BBL: long head of biceps brachii, BRA: brachialis). S-EMG activity decreased at a higher frequency of 2.7 Hz and increased linearly with an increase in skin friction frequency (0.5-2.7 Hz) in BBS. A decrease in high-threshold motor unit (HT-MU) firing rate in superficial regions and an increase in low-threshold motor unit (LT-MU) firing rate in deeper regions were observed with skin friction (2.7 Hz) in BBS. The actions of inhibitory interneurons may be influenced by cutaneous afferent input with skin friction. Muscle activation of BBS depended on the intensity of the stimulus. Skin friction over BBS results in an inhibitory response in superficial regions of BBS, most likely due to the increase in firing rate of low-threshold cutaneous mechanoreceptors.
  Somatosensory & Motor Research 02/2013;
• Article: Age-related differences in cognitive function for interlimb coordination during split-belt walking: A pilot study.

  Mayumi Saito, Masaki Hyodo, Yoshihisa Masakado, Yutaka Tomita, Junichi Ushiba
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  ABSTRACT: While walking is considered a task demanding cognitive functions rather than an automatic motor task, it is still unclear whether cognitive tasks influence interlimb coordination during walking. The present study revealed that the elderly require cognitive function to control temporal interlimb coordination under difficult walking conditions. Risk of falls is thus likely to be increased in the elderly when performing attention-demanding tasks while walking.
  Somatosensory & Motor Research 01/2013;
• Article: Use of a cane for recovery from backward balance loss during treadmill walking.

  Masaki Hyodo, Mayumi Saito, Junichi Ushiba, Yutaka Tomita, Yoshihisa Masakado
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  ABSTRACT: Purpose. To study whether a cane improved balance recovery after perturbation during walking. Method. This study was a crossover comparison comparing the effect of walking with and without a cane for balance recovery after perturbation during treadmill walking. Five normal young volunteers participated. The velocity and acceleration of a marker sited on the seventh cerebral vertebra (C7) and vertical hand motion were measured by a motion analysis system. Result. When using a cane, C7 backward velocity increased by approximately 15% (413 SD 95 mm/s with cane vs. 358 SD 88 mm/s without). In addition, C7 backward acceleration increased by approximately 23% (3.2 SD 0.7 m/s(2) with cane vs. 2.6 SD 0.8 m/s(2) without) and the vertical motion of the right hand decreased (187 SD 98 mm with cane vs. 372 SD 260 mm without). Additionally, no subject was able to use a cane to broaden their base of support. Conclusions. The ability to limit trunk extension is crucial for preventing falls. Therefore, using a cane jeopardizes recovery from backward balance loss. The results encourage further research on the risk of a cane on balance recovery for the elderly population and habitual cane users.
  Somatosensory & Motor Research 01/2013;
• Article: Activation timing of soleus and tibialis anterior muscles during sit-to-stand and stand-to-sit in post-stroke vs. healthy subjects.

  Augusta Silva, Andreia S P Sousa, Rita Pinheiro, Joana Ferraz, João Manuel R S Tavares, Rubim Santos, Filipa Sousa
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  ABSTRACT: Introduction. Sit-to-stand (SitTS) and stand-to-sit (StandTS) are very important functional tasks that become compromised in stroke patients. As in other voluntary movements, they require an adequate postural control (PC) involving the generation of anticipatory postural adjustments (APAs). In order to give clues for more efficient and directed rehabilitation programs, a deeper knowledge about APAs during challenging and daily life movements is essential. Purpose. To analyze the activation timing of tibialis anterior (TA) and soleus (SOL) muscles during SitTS and StandTS in healthy subjects and in post-stroke patients. Methods. Two groups participated in this study: one composed of ten healthy subjects and the other by ten subjects with a history of stroke and increased H-reflex. Electromyographic activity (EMGa) of SOL and TA was analyzed during SitTS and StandTS in the ipsilateral (IPSI) and the contralateral (CONTRA) limb to the side lesion in stroke subjects, and in one limb in healthy subjects. A force plate was used to identify the movement onset. Results. In both sequences, in the stroke group SOL activation timing occurred prior to movement onset, contrary to the pattern observed in the healthy subjects. Statistically significant differences were found in SOL activation timings between each lower limb of the stroke and healthy groups, but no significant differences were found between the IPSI and the CONTRA limb. The TA activation timing seems to be delayed in the CONTRA limb when compared to the healthy subjects and showed a better organization of TA timing activation in StandTS when compared to SitTS. Conclusion. Compared to healthy subjects, APAs seem to be altered in both limbs of the post-stroke subjects, with the SOL activation timing being anticipated in both SitTS and StandTS.
  Somatosensory & Motor Research 01/2013;
• Article: Reliability of a new technique for intraoral mapping of somatosensory sensitivity.

  Shengyi Lu, Lene Baad-Hansen, Zhenting Zhang, Peter Svensson
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  ABSTRACT: Diagnosis of intraoral pain conditions may be facilitated by assessment of somatosensory sensitivity not only at a single test site but also at multiple test sites, that is, intraoral somatosensory mapping. No standardized mapping techniques are currently available. The aim of this study was to evaluate: (1) spatial variations in somatosensory sensitivity; (2) the reliability of a new technique for mapping of intraoral somatosensory sensitivity. Fifteen healthy volunteers participated in two experimental sessions. In each session, three mechanical stimuli (32 mN and 512 mN von Frey and electronic von Frey (EVF)) were each applied to 15 test sites in a 5 × 3 matrix located at the gingivomucosal area adjacent to the upper premolar region on both sides. A custom-made silicone-based template secured standardization of the test sites. The subjects rated the perceived intensity on a 0-50-100 numerical rating scale (NRS) for tactile (32 mN) and pinprick (512 mN) stimuli and determined the pinprick threshold (PiPT) by EVF by pushing a stop button. Analyses of variance for NRS scores and PiPT for all three stimulus modalities showed no significant differences between sessions or sides (p = 0.077), whereas there were significant site-to-site differences (p < 0.001). Generally, the anterior and apical regions were more sensitive than posterior and cervical regions. Intraclass correlation coefficients for between session reliability ranged between 0.76 and 0.87 for NRS scores and PiPT measures. In conclusion, good test-retest reliability of intraoral somatosensory mapping was found with the help of a new template, which can be used for further studies of intraoral pain mechanisms.
  Somatosensory & Motor Research 12/2012;
• Article: Neural coding in the Non-Pacinian I tactile channel: A psychophysical and simulation study of magnitude estimation.

  Burak Güçlü, S Mete Dinçer
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  ABSTRACT: Psychophysical experiments and model simulations were performed to identify plausible neural codes representing stimulus magnitude in the Non-Pacinian I (NP I) tactile channel associated with rapidly adapting fibers. Sinusoidal mechanical displacements were applied on the fingertips of eight human subjects. The NP I channel was isolated by elevating the thresholds of the Pacinian (P) channel during forward masking. Psychophysical magnitude estimates were obtained at 40 Hz for the NP I channel and at 250 Hz for the P channel by using a small contactor (radius: 2 mm). The P channel was additionally tested with a larger contactor (radius: 4.3 mm) to compensate for the lower innervation density of the Pacinian fibers. The magnitude estimates were fitted by power functions. The exponent (1.02) obtained with the large contactor for the P channel was higher than the exponent (0.68) obtained with the small contactor, but it was not statistically different from the exponent (1.21) obtained with the small contactor for the NP I channel. This suggests that the exponent increases when more fibers are recruited in the P channel. Six hypothetical neural codes were tested by using a computational population model for the rapidly adapting afferents. The validity of each code was evaluated by comparing psychophysical and simulation exponents, by finding the correlations between the magnitude estimates and the neural code results, and by a novel distance metric for measuring the proximity between the data sets. The codes based on the number of active fibers, the total spike count, the mean and the standard deviation of the spike count distribution yielded the best results, while the codes based on the interspike intervals were not related with the magnitude estimates.
  Somatosensory & Motor Research 11/2012;
• Article: Biomechanical and neurophysiological mechanisms related to postural control and efficiency of movement: A review.

  Andreia S P Sousa, Augusta Silva, João Manuel R S Tavares
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  ABSTRACT: Understanding postural control requires considering various mechanisms underlying a person's ability to stand, to walk, and to interact with the environment safely and efficiently. The purpose of this paper is to summarize the functional relation between biomechanical and neurophysiological perspectives related to postural control in both standing and walking based on movement efficiency. Evidence related to the biomechanical and neurophysiological mechanisms is explored as well as the role of proprioceptive input on postural and movement control.
  Somatosensory & Motor Research 10/2012;
• Article: Role of intra-operative neurophysiologic monitoring during decompression and neurolysis after peripheral nerve injury: Case report.

  Vittoria Nazzi, Roberto Cordella, Giuseppe Messina, Ivano Dones, Angelo Franzini
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  ABSTRACT: This paper reports the case of a patient presenting motor and sensitive deficits of the left forearm and hand after a traumatic injury of the median, ulnar, and radial nerves. Decompression and neurolysis of the three nerves was performed. Spontaneous electromyographic activity and the amplitude of compound muscle action potentials (CMAPs) were monitored. Surgery led to an increased amplitude of the aforesaid parameters and a long-term clinical improvement.
  Somatosensory & Motor Research 10/2012;
• Article: The effect of advance information about the sequence of a to-be-signaled motor response on corticospinal excitability during the foreperiod.

  Noriyuki Kamata, Yasuyuki Iwata, Akiyoshi Matsugi, Koichi Hiraoka
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  ABSTRACT: We investigated the effect of advance information about the sequence of a to-be-signaled motor response on corticospinal excitability during the foreperiod in healthy humans. Advance information about the sequence of a to-be-signaled motor response was provided by a precue signal 600 ms before a response signal during a warned choice reaction task. The precue signal indicated the sequence of one of three to-be-signaled motor responses: simple, repetitive, or sequential motor responses. The amplitude of the motor-evoked potential (MEP) decreased significantly 100 ms before the response signal in both the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles, but a significant decrease was present only in the APB muscle 300 ms before the response signal. The decrease in the MEP amplitude 100 ms before the response signal induced by the precue signal indicating the repetitive motor response was significantly smaller than that induced by the precue signal indicating the simple or sequential motor response in the FDI muscle, and was significantly smaller than that induced by the precue signal indicating the sequential motor response in the APB muscle. The decrease in corticospinal excitability in the middle foreperiod is larger when the advance information about a to-be-signaled motor response is unrelated to the muscle tested, and the decrease in the late foreperiod is affected by advance information about the sequence of a to-be-signaled motor response.
  Somatosensory & Motor Research 10/2012;