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  • 1.
    Borch Petersen, Eline
    et al.
    Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Institutet för handikappvetenskap (IHV). Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Logopedi, Audiologi och Otorhinolaryngologi. Eriksholm Research Centre.
    Wöstmann, Malte
    Department of Psychology, University of Lübeck, Lübeck, Germany.
    Obleser, Jonas
    Department of Psychology, University of Lübeck, Lübeck, Germany.
    Lunner, Thomas
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Logopedi, Audiologi och Otorhinolaryngologi. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Institutet för handikappvetenskap (IHV). Eriksholm Research Centre, Snekkersten, Denmark.
    Neural tracking of attended versus ignored speech is differentially affected by hearing loss2017Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 117, nr 1, s. 18-27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hearing loss manifests as a reduced ability to understand speech, particularly in multitalker situations. In these situations, younger normal-hearing listeners' brains are known to track attended speech through phase-locking of neural activity to the slow-varying envelope of the speech. This study investigates how hearing loss, compensated by hearing aids, affects the neural tracking of the speech-onset envelope in elderly participants with varying degree of hearing loss (n = 27, 62–86 yr; hearing thresholds 11–73 dB hearing level). In an active listening task, a to-be-attended audiobook (signal) was presented either in quiet or against a competing to-be-ignored audiobook (noise) presented at three individualized signal-to-noise ratios (SNRs). The neural tracking of the to-be-attended and to-be-ignored speech was quantified through the cross-correlation of the electroencephalogram (EEG) and the temporal envelope of speech. We primarily investigated the effects of hearing loss and SNR on the neural envelope tracking. First, we found that elderly hearing-impaired listeners' neural responses reliably track the envelope of to-be-attended speech more than to-be-ignored speech. Second, hearing loss relates to the neural tracking of to-be-ignored speech, resulting in a weaker differential neural tracking of to-be-attended vs. to-be-ignored speech in listeners with worse hearing. Third, neural tracking of to-be-attended speech increased with decreasing background noise. Critically, the beneficial effect of reduced noise on neural speech tracking decreased with stronger hearing loss. In sum, our results show that a common sensorineural processing deficit, i.e., hearing loss, interacts with central attention mechanisms and reduces the differential tracking of attended and ignored speech.

  • 2.
    Compte, A.
    et al.
    Volen Center for Complex Systems, Brandeis University, Waltham, MA 02454, United States, Instituto de Neurociencias, Universidad Miguel Hernandez-CSIC, 03550 San Juan de Alicante, Spain.
    Constantinidis, C.
    Section of Neurobiology, Yale School of Medicine, New Haven, CT 06520, United States.
    Tegnér, Jesper
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologiska Beräkningar.
    Raghavachari, S.
    Volen Center for Complex Systems, Brandeis University, Waltham, MA 02454, United States.
    Chafee, M.V.
    Section of Neurobiology, Yale School of Medicine, New Haven, CT 06520, United States.
    Goldman-Rakic, P.S.
    Section of Neurobiology, Yale School of Medicine, New Haven, CT 06520, United States.
    Wang, X.-J.
    Volen Center for Complex Systems, Brandeis University, Waltham, MA 02454, United States.
    Temporally Irregular Mnemonic Persistent Activity in Prefrontal Neurons of Monkeys during a Delayed Response Task2003Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 90, nr 5, s. 3441-3454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important question in neuroscience is whether and how temporal patterns and fluctuations in neuronal spike trains contribute to information processing in the cortex. We have addressed this issue in the memory-related circuits of the prefrontal cortex by analyzing spike trains from a database of 229 neurons recorded in the dorsolateral prefrontal cortex of 4 macaque monkeys during the performance of an oculomotor delayed-response task. For each task epoch, we have estimated their power spectrum together with interspike interval histograms and autocorrelograms. We find that 1) the properties of most (about 60%) neurons approximated the characteristics of a Poisson process. For about 25% of cells, with characteristics typical of interneurons, the power spectrum showed a trough at low frequencies (<20 Hz) and the autocorrelogram a dip near zero time lag. About 15% of neurons had a peak at <20 Hz in the power spectrum, associated with the burstiness of the spike train, 2) a small but significant task dependency of spike-train temporal structure: delay responses to preferred locations were characterized not only by elevated firing, but also by suppressed power at low (<20 Hz) frequencies, and 3) the variability of interspike intervals is typically higher during the mnemonic delay period than during the fixation period, regardless of the remembered cue. The high irregularity of neural persistent activity during the delay period is likely to be a characteristic signature of recurrent prefrontal network dynamics underlying working memory.

  • 3.
    Folmli, Brookes
    et al.
    Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, Australia.
    Turman, Bulent
    Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, Australia.
    Johnson, Peter
    Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, Australia.
    Abbott, Allan
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för fysioterapi. Linköpings universitet, Medicinska fakulteten. Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, Australia.
    Dose-response of somatosensory cortex repeated anodal transcranial direct current stimulation on vibrotactile detection: A randomized sham controlled trial2018Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This randomized sham-controlled trial investigated anodal transcranial direct current stimulation (tDCS) over the somatosensory cortex contralateral to hand dominance for dose-response (1mA-20 minutes x 5 days) effects on vibrotactile detection thresholds (VDT). VDT was measured before and after tDCS on days 1,3&5 for low (30hz) and high (200hz) frequency vibrations on the dominant and non-dominant hands in 29 healthy adults (mean age = 22.86; 15 males, 14 females). Only the dominant hand 200Hz VDT displayed statistically significant medium effect size improvement for mixed model analysis of variance time x group interaction for active tDCS compared to sham. Post Hoc contrasts were statistically significant for dominant hand 200Hz VDT on day 5 after tDCS compared to day 1 before tDCS , day 1 after tDCS and day 3 before tDCS. There was a linear dose-response improvement with dominant hand 200Hz VDT mean difference decreasing from day 1 before tDCS peaking at -15.5% (SD=34.9%) on day 5 after tDCS. Both groups showed learning effect trends over time for all VDT test conditions but only the non-dominant hand 30Hz VDT was statistically significant (p=0.03) though Post Hoc contrasts were non-significant after Sidak adjustment. No adverse effects for tDCS were reported. In conclusion, anodal tDCS 1mA-20 minutes x 5 days on the dominant sensory cortex can modulate a linear improvement of dominant hand high frequency VDT but not for low frequency or non-dominant hand VDT.

  • 4.
    Fridberger, Anders
    et al.
    Karolinska Institutet, Stockholm, Sweden.
    Zheng, Jiefu
    Oregon Health & Science University, Portland, USA.
    Parthasarathi, Anand
    Bose Corporation, Framingham, Massachusetts, USA.
    Ren, Tianying
    Oregon Health & Science University, Portland, USA.
    Nuttall, Alfred
    Oregon Health & Science University, Portland, USA.
    Loud sound-induced changes in cochlear mechanics2002Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 88, nr 5, s. 2341-2348Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate the inner ear response to intense sound and the mechanisms behind temporary threshold shifts, anesthetized guinea pigs were exposed to tones at 100-112 dB SPL. Basilar membrane vibration was measured using laser velocimetry, and the cochlear microphonic potential, compound action potential of the auditory nerve, and local electric AC potentials in the organ of Corti were used as additional indicators of cochlear function. After exposure to a 12-kHz intense tone, basilar membrane vibrations in response to probe tones at the characteristic frequency of the recording location (17 kHz) were transiently reduced. This reduction recovered over the course of 50 ms in most cases. Organ of Corti AC potentials were also reduced and recovered with a time course similar to the basilar membrane. When using a probe tone at either 1 or 4 kHz, organ of Corti AC potentials were unaffected by loud sound, indicating that transducer channels remained intact. In most experiments, both the basilar membrane and the cochlear microphonic response to the 12-kHz overstimulation was constant throughout the duration of the intense stimulus, despite a large loss of cochlear sensitivity. It is concluded that the reduction of basilar membrane velocity that followed loud sound was caused by changes in cochlear amplification and that the cochlear response to intense stimulation is determined by the passive mechanical properties of the inner ear structures.

  • 5.
    Granseth, Björn
    et al.
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Lindström, Sivert
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Unitary EPSCs of corticogeniculate fibers in the rat dorsal lateral geniculate nucleus in vitro2003Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 89, nr 6, s. 2952-2960Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate unitary corticogeniculate excitatory postsynaptic currents (EPSCs), whole cell patch-clamp recordings were obtained from 20 principal cells in slices of the dorsal lateral geniculate nucleus (dLGN) of DA-HAN rats. EPSCs, evoked by electrical stimulation of corticogeniculate axons, had size distributions with one or more quantal peaks. Gaussian curves fitted to such distributions gave a mean quantal size (q) of -5.0 ± 0.7 (SD) pA for the EPSCs. Paired-pulse ratio (EPSC2/EPSC1) was 3.3 ± 0.9 for stimuli separated by 40 ms. The mean quantal size was similar for facilitated EPSCs (-5.2 ± 0.8 pA), implying an increase in mean quantal content (m). Most corticogeniculate axons were capable of releasing only one or two quanta onto individual principal cells. Mean resting release probability (p) was low, 0.09 ± 0.04. Binomial models, with the same n but increased p, could account for both the basal and facilitated EPSC size distributions in 6/8 cells. It is suggested that the low resting efficacy of corticogeniculate synapses serves to stabilize this excitatory feedback system. The pronounced facilitation in conjunction with large convergence from many corticogeniculate cells would provide a transient, potent excitation of dLGN cells, compliant with the idea of a visually driven neuronal amplifier.

  • 6.
    Perini, Irene
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för neuro- och inflammationsvetenskap. Linköpings universitet, Medicinska fakulteten.
    Tavakoli, Mitra
    University of Manchester, England; National Institute Health Research Collaborat Leadership Appl Hlt, England; University of Exeter, England.
    Marshall, Andrew
    Salford Royal Hospital NHS Trust, England; University of Manchester, England; Liverpool John Moores University, England.
    Minde, Jan
    Umeå University Hospital, Sweden.
    Morrison, India
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för neuro- och inflammationsvetenskap. Linköpings universitet, Medicinska fakulteten.
    Rare human nerve growth factor-beta mutation reveals relationship between C-afferent density and acute pain evaluation2016Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 116, nr 2, s. 425-430Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rare nerve growth factor-beta (NGFB) mutation R221W causes a selective loss of thinly myelinated fibers and especially unmyelinated C-fibers. Carriers of this mutation show altered pain sensation. A subset presents with arthropathic symptoms, with the homozygous most severely affected. The aim of the present study was to investigate the relationship between peripheral afferent loss and pain evaluation by performing a quantification of small-fiber density in the cornea of the carriers, relating density to pain evaluation measures. In vivo corneal confocal microscopy (CCM) was used to quantify C-fiber loss in the cornea of 19 R221W mutation carriers (3 homozygous) and 19 age-matched healthy control subjects. Pain evaluation data via the Situational Pain Questionnaire (SPQ) and the severity of neuropathy based on the Neuropathy Disability Score (NDS) were assessed. Homozygotes, heterozygotes, and control groups differed significantly in corneal C-nerve fiber density, with the homozygotes showing a significant afferent reduction. Importantly, peripheral C-fiber loss correlated negatively with pain evaluation, as revealed by SPQ scores. This study is the first to investigate the contribution of small-fiber density to the perceptual evaluation of pain. It demonstrates that the lower the peripheral small-fiber density, the lower the degree of reported pain intensity, indicating a functional relationship between small-fiber density and higher level pain experience.

  • 7.
    Ulfendahl, M.
    et al.
    Karolinska Institutet, Stockholm, Sweden.
    Khanna, S. M.
    Karolinska Institutet, Stockholm, Sweden.
    Fridberger, Anders
    Karolinska Institutet, Stockholm, Sweden.
    Flock, Å.
    Karolinska Institutet, Stockholm, Sweden.
    Flock, B.
    Karolinska Institutet, Stockholm, Sweden.
    Jäger, W.
    Karolinska Institutet, Stockholm, Sweden.
    Mechanical response characteristics of the hearing organ in the low-frequency regions of the cochlea1996Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 76, nr 6, s. 3850-3862Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. With the use of an in vitro preparation of the guinea pig temporal bone, in which the apical turns of the cochlea are exposed, the mechanical and electrical responses of the cochlea in the low-frequency regions were studied during sound stimulation. 2. The mechanical characteristics were investigated in the fourth and third turns of the cochlea with the use of laser heterodyne interferometry, which allows the vibratory responses of both sensory and supporting cells to be recorded. The electrical responses, which can be maintained for several hours, were recorded only in the most apical turn. 3. In the most apical turn, the frequency locations and shapes of the mechanical and electrical responses were very similar. 4. The shapes of the tuning curves and the spatial locations of the frequency maxima in the temporal bone preparation compared very favorably with published results from in vivo recordings of hair cell receptor potentials and sound-induced vibrations of the Reissner's membrane. 5. Compressive nonlinearities were present in both the mechanical and the electrical responses at moderate sound pressure levels. 6. The mechanical tuning changed along the length of the cochlea, the center frequencies in the fourth and third turns being approximately 280 and 570 Hz, respectively. 7. The mechanical responses of sensory and supporting cells were almost identical in shape but differed significantly in amplitude radially across the reticular lamina.

  • 8.
    Watkins, Roger H.
    et al.
    University of Gothenburg, Sweden; University of Bristol, England.
    Wessberg, Johan
    University of Gothenburg, Sweden.
    Backlund Wasling, Helena
    University of Gothenburg, Sweden.
    Dunham, James P.
    Cambridge University Hospital, England.
    Olausson, Håkan
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Centrum för social och affektiv neurovetenskap. Linköpings universitet, Medicinska fakulteten. University of Gothenburg, Sweden.
    Johnson, Richard D.
    University of Gothenburg, Sweden; University of Florida, FL 32610 USA.
    Ackerley, Rochelle
    University of Gothenburg, Sweden; Aix Marseille University, France.
    Optimal delineation of single C-tactile and C-nociceptive afferents in humans by latency slowing2017Ingår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 117, nr 4, s. 1608-1614Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    C-mechanoreceptors in humans comprise a population of unmyelinated afferents exhibiting a wide range of mechanical sensitivities. C-mechanoreceptors are putatively divided into those signaling gentle touch (C-tactile afferents, CTs) and nociception (C-mechanosensitive nociceptors, CMs), giving rise to positive and negative affect, respectively. We sought to distinguish, compare, and contrast the properties of a population of human C-mechanoreceptors to see how fundamental the divisions between these putative subpopulations are. We used microneurography to record from individual afferents in humans and applied electrical and mechanical stimulation to their receptive fields. We show that C-mechanoreceptors can be distinguished unequivocally into two putative populations, comprising CTs and CMs, by electrically evoked spike latency changes (slowing). After both natural mechanical stimulation and repetitive electrical stimulation there was markedly less latency slowing in CTs compared with CMs. Electrical receptive field stimulation, which bypasses the receptor end organ, was most effective in classifying C-mechanoreceptors, as responses to mechanical receptive field stimulation overlapped somewhat, which may lead to misclassification. Furthermore, we report a subclass of low-threshold CM responding to gentle mechanical stimulation and a potential subclass of CT afferent displaying burst firing. We show that substantial differences exist in the mechanisms governing axonal conduction between CTs and CMs. We provide clear electrophysiological "signatures" (extent of latency slowing) that can be used in unequivocally identifying populations of C-mechanoreceptors in single-unit and multiunit microneurography studies and in translational animal research into affective touch. Additionally, these differential mechanisms may be pharmacologically targetable for separate modulation of positive and negative affective touch information. NEW amp; NOTEWORTHY Human skin encodes a plethora of touch interactions, and affective tactile information is primarily signaled by slowly conducting C-mechanoreceptive afferents. We show that electrical stimulation of low-threshold C-tactile afferents produces markedly different patterns of activity compared with high-threshold C-mechanoreceptive nociceptors, although the populations overlap in their responses to mechanical stimulation. This fundamental distinction demonstrates a divergence in affective touch signaling from the first stage of sensory processing, having implications for the processing of interpersonal touch.

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