126
|
Sfienti C, Adrich P, Aumann T, Bacri CO, Barczyk T, Bassini R, Bianchin S, Boiano C, Botvina AS, Boudard A, Brzychczyk J, Chbihi A, Cibor J, Czech B, De Napoli M, Ducret JE, Emling H, Frankland JD, Hellström M, Henzlova D, Immè G, Iori I, Johansson H, Kezzar K, Lafriakh A, Le Fèvre A, Le Gentil E, Leifels Y, Lühning J, Lukasik J, Lynch WG, Lynen U, Majka Z, Mocko M, Müller WFJ, Mykulyak A, Orth H, Otte AN, Palit R, Pawłowski P, Pullia A, Raciti G, Rapisarda E, Sann H, Schwarz C, Simon H, Sümmerer K, Trautmann W, Tsang MB, Verde G, Volant C, Wallace M, Weick H, Wiechula J, Wieloch A, Zwiegliński B. Isotopic dependence of the nuclear caloric curve. PHYSICAL REVIEW LETTERS 2009; 102:152701. [PMID: 19518626 DOI: 10.1103/physrevlett.102.152701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Indexed: 05/27/2023]
Abstract
The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of (124)Sn and radioactive beams of (124)La and (107)Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (DeltaT approximately 0.6 MeV) appear for residue production near the onset of multifragmentation.
Collapse
|
127
|
Arndt S, Schwarz C. Mütterliche Erschöpfung im Wochenbett – Ergebnisse einer Befragung von Müttern zwei Monate nach der Geburt. Z Geburtshilfe Neonatol 2009. [DOI: 10.1055/s-0029-1223004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
128
|
Heidrich T, Schwarz C. Stillhäufigkeit und -dauer von Säuglingen im Alter von zwei Monaten – Ost-West-Vergleich und Einfluss von Betreuung im Wochenbett durch Hebammen. Z Geburtshilfe Neonatol 2009. [DOI: 10.1055/s-0029-1222924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
129
|
Schwarz C, Salzmann J. 574 Étude des indicateurs cliniques associés à l’hyposphagma. J Fr Ophtalmol 2009. [DOI: 10.1016/s0181-5512(09)73698-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
130
|
Ott S, Schönfeld N, Schwarz C, Bauer TT. Narrow Band Imaging (NBI) bei der medizinischen Thorakoskopie. Pneumologie 2009. [DOI: 10.1055/s-0029-1213905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
131
|
Schwarz C, Bittner R, Kirsch A, Loddenkemper C, Mairinger T, Schönfeld N, Serke M, Loddenkemper R. A 62-Year-Old Woman with Bilateral Pleural Effusions and Pulmonary Infiltrates Caused by Extramedullary Hematopoiesis. Respiration 2009; 78:110-3. [DOI: 10.1159/000150913] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 06/10/2008] [Indexed: 11/19/2022] Open
|
132
|
Piechotowski I, Brockmann SO, Schwarz C, Winter CH, Ranft U, Pfaff G. Emergence of hantavirus in South Germany: rodents, climate and human infections. Parasitol Res 2008; 103 Suppl 1:S131-7. [PMID: 19030895 DOI: 10.1007/s00436-008-1055-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 05/26/2008] [Indexed: 11/30/2022]
Abstract
Human hantavirus (serotype Puumala) infections are prevalent throughout Europe. The bank vole is the main reservoir of the Puumala virus (PUUV). Between 2001 and 2006, the annual incidences in Germany ranged from 0.1 to 0.5 per 100,000 inhabitants. About half of the cases were reported from the state of Baden-Württemberg (BW) in southwest Germany. In 2007, 1,089 PUUV infections were reported from BW. This reflects an incidence of 10.1:100,000, which is more than 11 times higher than the mean incidence of the previous 6 years. Spatial analysis highlights incidences up to 90:100,000 in the most affected district. The winter season 2006/2007 showed an all time high in reported mean temperature. The previous summer and autumn led to a beech mast year, resulting in favourable feed conditions for bank voles in the winter season 2006/2007. The causes of the observed increase in PUUV infections in 2007 cannot be restricted to known cycles in the bank vole population. Favourable feed conditions, a mild winter and an early onset of spring may have influenced bank vole population size as well as human exposure to infectious rodent excretions. Further epidemiologic studies are necessary to better understand the interaction between environmental factors, occurrence of Puumala virus in bank voles and the risk for human disease.
Collapse
|
133
|
Lindner G, Schwarz C, Kneidinger N, Kramer L, Oberbauer R, Druml W. Can we really predict the change in serum sodium levels? An analysis of currently proposed formulae in hypernatraemic patients. Nephrol Dial Transplant 2008; 23:3501-8. [DOI: 10.1093/ndt/gfn476] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
134
|
Stüttgen MC, Kullmann S, Schwarz C. Responses of Rat Trigeminal Ganglion Neurons to Longitudinal Whisker Stimulation. J Neurophysiol 2008; 100:1879-84. [DOI: 10.1152/jn.90511.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Responses of rat trigeminal ganglion neurons to longitudinal whisker stimulation. Rats use their mobile set of whiskers to actively explore their environment. Parameters that play a role to generate movement dynamics of the whisker shaft within the follicle, thus activating primary afferents, are manifold: among them are mechanical properties of the whiskers (curvature, elasticity and taper), active movements (head, body, and whiskers), and finally, object characteristics (surface, geometry, position, and orientation). Hence the whisker system is confronted with forces along all three axes in space. Movements along the two latitudinal axes of the whisker (horizontal and vertical) have been well studied. Here we focus on movement along the whisker's longitudinal axis that has been neglected so far. We employed ramp-and-hold movements that pushed the whisker shaft toward the skin and quantified the resulting activity in trigeminal first-order afferents in anesthetized rats. Virtually all recorded neurons were highly sensitive to longitudinal movement. Neurons could be perfectly segregated into two groups according to their modulation by stimulus amplitude and velocity, respectively. This classification regimen correlated perfectly with the presence or absence of slowly adapting responses in longitudinal stimulation but agreed with classification derived from latitudinal stimulation only if the whisker was engaged in its optimal direction and set point. We conclude that longitudinal stimulation is an extremely effective means to activate the tactile pathway and thus is highly likely to play an important role in tactile coding on the ascending somatosensory pathway. In addition, compared with latitudinal stimulation, it provides a reliable and easy to use method to classify trigeminal first-order afferents.
Collapse
|
135
|
Heidrich T, Schwarz C, Robra BP. Stillquoten von Säuglingen im Alter von zwei Monaten – Ost-West-Vergleich und Einfluss von Hebammenbetreuung. DAS GESUNDHEITSWESEN 2008. [DOI: 10.1055/s-0028-1086396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
136
|
Bott S, Schwarz C, Robra BP. Einfluss von Hebammenbetreuung auf postpartale Erschöpfungszustände. DAS GESUNDHEITSWESEN 2008. [DOI: 10.1055/s-0028-1086395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
137
|
Nawrodt R, Zimmer A, Koettig T, Schwarz C, Heinert D, Hudl M, Neubert R, Thürk M, Nietzsche S, Vodel W, Seidel P, Tünnermann A. High mechanical Q-factor measurements on silicon bulk samples. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/122/1/012008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
138
|
Schwarz C, Dang Burgener NPL, Dosso AA. [OCT Visante observation of the progression of a perforated neurotrophic cornea ulcer treated with amniotic membrane grafts]. J Fr Ophtalmol 2008; 31:419-21. [PMID: 18563043 DOI: 10.1016/s0181-5512(08)71438-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
INTRODUCTION The optical coherence tomography (OCT) Visante provides easy, high-resolution observation free of contact with the cornea and anterior segment. We present the progression of a neurotrophic corneal ulcer treated with amniotic membrane grafts studied with this system. METHODS A 71-year-old patient with facial nerve paresis secondary to vestibular schwannoma surgery presented with a neurotrophic perforated corneal ulcer. Since medical treatment had failed, we performed an amniotic membrane graft. The OCT Visante was used for follow-up for 2 months. RESULTS Progression was slow but the perforation eventually closed. Cicatrization of the corneal ulcer was followed with the OCT Visante to document the healing process and corneal thickness. CONCLUSION Optical coherence tomography Visante provides easy visualization and high-resolution documentation with no contact with the healing corneal ulcerations.
Collapse
|
139
|
Schwarz C, Dang Burgener N, Dosso A. 392 Comparaison entre l’utilisation d’une lentille AR40 et Tecnis Z9000 chez 10 patients opérés de la cataracte. J Fr Ophtalmol 2008. [DOI: 10.1016/s0181-5512(08)70990-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
140
|
Le Gentil E, Aumann T, Bacri CO, Benlliure J, Bianchin S, Böhmer M, Boudard A, Brzychczyk J, Casarejos E, Combet M, Donadille L, Ducret JE, Fernandez-Ordoñez M, Gernhäuser R, Johansson H, Kezzar K, Kurtukian-Nieto T, Lafriakh A, Lavaud F, Le Fèvre A, Leray S, Lühning J, Lukasik J, Lynen U, Müller WFJ, Pawlowski P, Pietri S, Rejmund F, Schwarz C, Sfienti C, Simon H, Trautmann W, Volant C, Yordanov O. Coincidence measurement of residues and light particles in the reaction 56Fe+p at 1 GeV per nucleon with the spallation reactions setup SPALADIN. PHYSICAL REVIEW LETTERS 2008; 100:022701. [PMID: 18232861 DOI: 10.1103/physrevlett.100.022701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Indexed: 05/25/2023]
Abstract
The spallation of 56Fe in collisions with hydrogen at 1A GeV has been studied in inverse kinematics with the large-aperture setup SPALADIN at GSI. Coincidences of residues with low-center-of-mass kinetic energy light particles and fragments have been measured allowing the decomposition of the total reaction cross section into the different possible deexcitation channels. Detailed information on the evolution of these deexcitation channels with excitation energy has also been obtained. The comparison of the data with predictions of several deexcitation models coupled to the INCL4 intranuclear cascade model shows that only GEMINI can reasonably account for the bulk of collected results, indicating that in a light system with no compression and little angular momentum, multifragmentation might not be necessary to explain the data.
Collapse
|
141
|
Schönfeld N, Temme T, Schwarz C, Serke M, Ott S. [Modern endoscopic procedures for diseases of the respiratory tract]. Dtsch Med Wochenschr 2007; 132:2633-6. [PMID: 18050029 DOI: 10.1055/s-2007-993111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Bronchoscopy is the most important diagnostic procedure for the work-up of central bronchial processes and parenchymal lung diseases, such as lung cancer, pneumonias or diffuse lung diseases. Recent progress - ultrasound, navigation systems or ultrathin bronchoscopes - was made to achieve a better yield in the diagnosis of peripheral and peribronchial lesions. Bronchial recanalisation by thermal ablation or stenting is mainly performed with rigid instruments; these procedures as well as brachytherapy in local anaesthesia should be restricted to specialized centers. If pleuracentesis does not provide the etiology of pleural effusion, thoracoscopy in local anaesthesia is the method of choice. The procedure does not only provide a definite diagnosis for almost all of the patients, it also allows the immediate option for talcum poudrage in case of pleural malignancy.
Collapse
|
142
|
Butovas S, Schwarz C. Detection psychophysics of intracortical microstimulation in rat primary somatosensory cortex. Eur J Neurosci 2007; 25:2161-9. [PMID: 17419757 DOI: 10.1111/j.1460-9568.2007.05449.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A problem of purposeful intracortical microstimulation is the long duration of neuronal integration time and the associated complex temporal interactions of effects to individual pulses in trains. Here we investigated the effects of repetitive stimuli on perception. We trained head-restraint rats to indicate the detection of cortical microstimulation in infragranular layers of barrel cortex. Three stimulus parameters: stimulus intensity, number of pulses and frequency were varied, and psychometric detection curves were assessed using the method of constant stimuli. The average psychophysical threshold of single pulses was 2.0 nC--a measure very close to what has been found earlier for the evocation of short-latency action potentials in neurons near the stimulation electrode. Detection of single-pulse stimulation always saturated at probabilities of about 0.8. In contrast, repetitive stimuli gave rise to lower thresholds (by a factor of two at 15 pulses, 320 Hz), and to saturation at probabilities close to 1. Interestingly, a large fraction of these perceptual benefits was observed already with double pulses. Moreover, the perceptual efficacy of individual pulses was higher using double pulses compared with longer sequences, i.e. double pulses were detected better than expected from the assumption of independence of single-pulse effects, while trains of 15 pulses fell well short of this expectation. The present results thus point to double-pulse stimulation as an optimal choice when trading economic stimulation against optimizing of the percept.
Collapse
|
143
|
Schwarz C. Geburtshilfliche Risiken gesunder Frauen mit komplikationsloser Schwangerschaft – Wie Hebammen verschiedener europäischer Länder die Risiken einschätzen. Z Geburtshilfe Neonatol 2007. [DOI: 10.1055/s-2007-1002864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
144
|
Schwarz C. Das Alter der Schwangeren als Geburtsrisiko – Alter ist kein Grund für mehr geburtshilfliche Interventionen. Z Geburtshilfe Neonatol 2007. [DOI: 10.1055/s-2007-1002899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
145
|
Schwarz C, Kümmerle JM, Theiss F, Auer JA. Correction of complicated angular limb deformities in a foal: a case report. PFERDEHEILKUNDE 2007. [DOI: 10.21836/pem20070507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
146
|
Kirsch BM, Sunder-Plassmann G, Schwarz C. Metabolic alkalosis in a hemodialysis patient successful treatment with a proton pump inhibitor. Clin Nephrol 2006; 66:391-4. [PMID: 17140170 DOI: 10.5414/cnp66391] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hemodialysis patients develop metabolic acidosis due to their impaired excretion of daily produced protons (H+). The following report will show a rare case of severe metabolic alkalosis (predialysis pH 7.52, base excess (BE) +17) in a hemodialysis woman caused by self-provoked upper gastrointestinal H+ losses based on an eating disorder. Treatment with a proton pump inhibitor resulted in the normalization of acid/base homeostasis (predialysis pH 7.40, BE +1.6).
Collapse
|
147
|
Butovas S, Hormuzdi SG, Monyer H, Schwarz C. Effects of electrically coupled inhibitory networks on local neuronal responses to intracortical microstimulation. J Neurophysiol 2006; 96:1227-36. [PMID: 16837655 DOI: 10.1152/jn.01170.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using in vivo multielectrode electrophysiology in mice, we investigated the underpinnings of a local, long-lasting firing rate suppression evoked by intracortical microstimulation. Synaptic inhibition contributes to this suppression as it was reduced by pharmacological blockade of gamma-aminobutyric acid type B (GABAB) receptors. Blockade of GABAB receptors also abolished the known sublinear addition of inhibitory response duration after repetitive electrical stimulation. Furthermore, evoked inhibition was weaker and longer in connexin 36 knockout (KO) mice that feature decoupled cortical inhibitory networks. In supragranular layers of KO mice even an unusually long excitatory response (< or = 50 ms) appeared that was never observed in wild-type (WT) mice. Furthermore, the spread and duration of very fast oscillations (> 200 Hz) evoked by microstimulation at a short latency were strongly enhanced in KO mice. In the spatial domain, lack of connexin 36 unmasked a strong anisotropy of inhibitory spread. Although its reach along layers was almost the same as that in WT mice, the spread across cortical depth was severely hampered. In summary, the present data suggest that connexin 36-coupled networks significantly shape the electrically evoked cortical inhibitory response. Electrical coupling renders evoked cortical inhibition more precise and strong and ensures a uniform spread along the two cardinal axes of neocortical geometry.
Collapse
|
148
|
Abstract
The idiom renal osteodystrophy (ROD) represents a heterogeneous pattern of bone disturbances caused by chronic renal insufficiency and concomitant diseases. For the clinical decision of therapy it is most important to differentiate between high and low or adynamic turnover ROD because the therapeutically consequences of these two ends of the ROD spectrum are fundamentally different. Bone histology remains the gold standard for the exact classification of ROD. Serological markers of bone metabolism are not suited for the accurate nomenclature of ROD but are useful for the sequential follow up of ROD after a clear diagnosis has been made. Similarly, radiological diagnosis of ROD using dual energy X-ray absorptiometry (DEXA) or quantitative computer tomography scan (q-CT) is inaccurate and thus more suited for the routine follow up of established disease. Besides mineralization, bone strength and the rate of fractures are strongly determined by the architecture of the bone matrix. This information, however, is also only available on bone biopsy sections and cannot be estimated by non-invasive diagnostic methods. In summary, bone biopsy should be used more liberally for correct classification of bone disease. The sequential follow up and guidance of therapy success can be performed by non-invasive procedures such as biochemical bone marker determination in blood. X-ray imaging and densitometry is suitable only for sequential evaluation of osteoporosis.
Collapse
|
149
|
Linnemann C, Schmeh I, Thier P, Schwarz C. Transient change in GABA(A) receptor subunit mRNA expression in Lurcher cerebellar nuclei during Purkinje cell degeneration. BMC Neurosci 2006; 7:59. [PMID: 16872511 PMCID: PMC1544347 DOI: 10.1186/1471-2202-7-59] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 07/27/2006] [Indexed: 12/02/2022] Open
Abstract
Background Lurcher mice suffer from a complete Purkinje cell (PC) loss in the first four postnatal weeks. Parallel to this degeneration, GABAergic synapses in the deep cerebellar nuclei (DCN), the major recipient of the inhibitory PC projection, increase synaptic conductance. Here, we further investigated this phenomenon, using real-time RT-PCR to assess GABAA receptor subunit gene expression during PC degeneration. Results We observed a specific reduction in γ2 subunit gene expression, while α1–5, β1–2, γ1,3 and δ subunits were unaffected. We made two further specific findings. First, the difference in gene expression was shown in tissue from DCN only. Neither the hippocampus nor coronal sections through the forebrain showed such effects. Furthermore, the involvement of different levels of corticosterone, a possible humeral trigger for differences in gene expression, could be excluded. Second, like the known potentiation of GABAergic synapses, the γ2 down-regulation was present only after the onset of degeneration at p14. The difference in γ2 mRNA expression, however, appeared transient, since it was no longer detectable in adult Lurcher mice. Conclusion In conclusion, the down-regulation of γ2 subunits may be related to differences in synaptic efficacy and, as such, may reflect the initial phase of adaptive responses of DCN tissue to massive GABAergic deafferentation. Its transient course, however, does not support the idea that modulations in GABAergic transmission are at the basis of the well-known DCN-based functional benefit of Lurcher mice present throughout their life.
Collapse
|
150
|
Stüttgen MC, Rüter J, Schwarz C. Two psychophysical channels of whisker deflection in rats align with two neuronal classes of primary afferents. J Neurosci 2006; 26:7933-41. [PMID: 16870738 PMCID: PMC6674210 DOI: 10.1523/jneurosci.1864-06.2006] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 06/10/2006] [Accepted: 06/16/2006] [Indexed: 11/21/2022] Open
Abstract
The rat whisker system has evolved into in an excellent model system for sensory processing from the periphery to cortical stages. However, to elucidate how sensory processing finally relates to percepts, methods to assess psychophysical performance pertaining to precise stimulus kinematics are needed. Here, we present a head-fixed, behaving rat preparation that allowed us to measure detectability of a single whisker deflection as a function of amplitude and peak velocity. We found that velocity thresholds for detection of small-amplitude stimuli (<3 degrees) were considerably higher than for detection of large-amplitude stimuli (>3 degrees). This finding suggests the existence of two psychophysical channels mediating detection of whisker deflection: one channel exhibiting high amplitude and low velocity thresholds (W1), and the other channel exhibiting high velocity and low amplitude thresholds (W2). The correspondence of W1 to slowly adapting (SA) and W2 to rapidly adapting (RA) neuronal classes in the trigeminal ganglion was revealed in acute neurophysiological experiments. Neurometric plots of SA and RA cells were closely aligned to psychophysical performance in the corresponding W1 and W2 parameter ranges. Interestingly, neurometric data of SA cells fit the behavior best if it was based on a short time window integrating action potentials during the initial phasic response, in contrast to integrating across the tonic portion of the response. This suggests that detection performance in both channels is based on the assessment of very few spikes in their corresponding groups of primary afferents.
Collapse
|