Leibniz Institute For Neurobiologie

Magdeburg, Germany

Leibniz Institute For Neurobiologie

Magdeburg, Germany
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Goetze B.,Institute For Allgemeine Zoologie Und Tierphysiologie | Schmidt K.-F.,Institute For Allgemeine Zoologie Und Tierphysiologie | Lehmann K.,Institute For Allgemeine Zoologie Und Tierphysiologie | Altrock W.D.,Leibniz Institute For Neurobiologie | And 2 more authors.
NeuroImage | Year: 2010

How little neurotransmission in the visual system is sufficient to promote decent visual capabilities? This question is of key importance for therapeutic approaches to restore vision in patients who suffer from degenerative retinal diseases. In the retinae of mice, mutant for the presynaptic scaffolding protein Bassoon (Bsn), signal transfer at photoreceptor ribbon synapses is severely disturbed due to impaired ribbon attachment to the active zone. We have used two different behavioural tasks and optical imaging of intrinsic signals to probe vision in young and adult Bsn-/- mice and their wild-type littermates. Here we show that while visual acuity was significantly reduced in mutants compared to controls, vision guided behavioural decisions and optical imaging revealed essentially unperturbed cortical signals and retinotopy in spite of the photoreceptor synaptopathy. In addition, both vision and visual cortical maps were adult-like at 4 weeks of age. These results show that (i) while Bassoon-dependent fast exocytosis is essential for normal vision surprisingly good visual performance can be achieved in the absence of synaptic ribbons, (ii) both the development and maintenance of visual cortical maps is independent of synaptic ribbons and (iii) visual development in the mutants is completed at 4 weeks of age indicating that later developing ectopic synapses do not affect vision. Thus, the central visual system can make use of slow and weak retinal signals to subserve surprisingly robust vision. © 2009 Elsevier Inc. All rights reserved.

Yeritsyan N.,Leibniz Institute For Neurobiologie | Lehmann K.,Friedrich - Schiller University of Jena | Puk O.,Helmholtz Center for Environmental Research | Graw J.,Helmholtz Center for Environmental Research | And 2 more authors.
European Journal of Neuroscience | Year: 2012

By combining behavioural analyses with intrinsic signal optical imaging, we analysed visual performance and visual cortical activity in the albino mouse strain BALB/c, which is increasingly being used as an animal model of neuropsychological disorders. Visual acuity, as measured by a virtual-reality optomotor system, was 0.12cycles per degree (cyc/deg) in BALB/c mice and 0.39cyc/deg in pigmented C57BL/6 mice. Surprisingly, BALB/c mice showed reflexive head movements against the direction of the rotating stimulus. Contrast sensitivity was significantly lower in BALB/c mice (45% contrast at 0.064cyc/deg) than in C57BL/6 mice (6% contrast). In the visual water task, visual acuity was 0.3cyc/deg in BALB/c mice and 0.59cyc/deg in C57BL/6 mice. Thus, the visual performance of BALB/c mice was significantly impaired in both behavioural tests - visual acuity was ~0.3cyc/deg lower than in C57BL/6 mice, and contrast sensitivity was reduced by a factor of ~8. In BALB/c mice, visual cortical maps induced by stimulation of the contralateral eye were normal in both activation strength and retinotopic map quality. In contrast, maps induced by ipsilateral eye stimulation differed significantly between the strains - activity in a region representing 15° to 19° elevation in the visual field was significantly weaker in BALB/c mice than in C57BL/6 mice. Taken together, our observations show that BALB/c mice, like the albino animals of other species, have a significantly lower visual performance than C57BL/6 mice and a modified cortical representation of the ipsilateral eye that may impair stereopsis. Thus, our results caution against disregarding vision as a confounding factor in behavioural tests of neuropsychological disorders. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Dityatev A.,Italian Institute of Technology | Seidenbecher C.I.,Leibniz Institute For Neurobiologie | Schachner M.,Zentrum fUr Molekulare Neurobiologie Hamburg | Schachner M.,Rutgers University
Trends in Neurosciences | Year: 2010

The extracellular matrix (ECM) of the central nervous system is well recognized as a migration and diffusion barrier that allows for the trapping and presentation of growth factors to their receptors at the cell surface. Recent data highlight the importance of ECM molecules as synaptic and perisynaptic scaffolds that direct the clustering of neurotransmitter receptors in the postsynaptic compartment and that present barriers to reduce the lateral diffusion of membrane proteins away from synapses. The ECM also contributes to the migration and differentiation of stem cells in the neurogenic niche and organizes the polarized localization of ion channels and transporters at contacts between astrocytic processes and blood vessels. Thus, the ECM contributes to functional compartmentalization in the brain. © 2010 Elsevier Ltd.

Coomber B.,University of Nottingham | Edwards D.,University of Nottingham | Jones S.J.,University of Nottingham | Shackleton T.M.,University of Nottingham | And 3 more authors.
Frontiers in Systems Neuroscience | Year: 2011

Reversible inactivation of the cortex by surface cooling is a powerful method for studying thefunction of a particular area. Implanted cooling cryoloops have been used to study the role ofindividual cortical areas in auditory processing of awake-behaving cats. Cryoloops have also been used in rodents for reversible inactivation of the cortex, but recently there has been a concern that the cryoloop may also cool non-cortical structures either directly or via the perfusion of blood, cooled as it passed close to the cooling loop. In this study we have confirmed that the loop can inactivate most of the auditory cortex without causing a significant reduction in temperature of the auditory thalamus or other subcortical structures. We placed a cryoloop on the surface of the guinea pig cortex, cooled it to 2°C and measured thermal gradients across the neocortical surface. We found that the temperature dropped to 20-24°C among cells within a radius of about 2.5 mm away from the loop. This temperature drop was sufficient to reduce activity of most cortical cells and led to the inactivation of almost the entire auditory region. When the temperature of thalamus, midbrain, and middle ear were measured directly during cortical cooling, there was a small drop in temperature (about 4°C) but this was not sufficient to directly reduce neural activity. In an effort to visualize the extent of neural inactivation we measured the uptake of thallium ions following an intravenous injection. This confirmed that there was a large reduction of activity across much of the ipsilateral cortex and only a small reduction in subcortical structures. © 2011 Coomber, Edwards, Jones, Shackleton, Goldschmidt, Wallace and Palmer.

Brosch M.,Leibniz Institute For Neurobiologie | Selezneva E.,Leibniz Institute For Neurobiologie | Scheich H.,Leibniz Institute For Neurobiologie
Frontiers in Systems Neuroscience | Year: 2011

It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these fndings, we study in detail properties of neuronal fring in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifcations were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal fring in auditory cortex that refected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively infuenced than lately recognized. © 2011 Brosch, Selezneva and Scheich.

Brosch M.,Leibniz Institute For Neurobiologie | Selezneva E.,Leibniz Institute For Neurobiologie | Scheich H.,Leibniz Institute For Neurobiologie
Hearing Research | Year: 2011

We review event-related slow firing changes in the auditory cortex and related brain structures. Two types of changes can be distinguished, namely increases and decreases of firing, lasting in the order of seconds. Triggering events can be auditory stimuli, reinforcers, and behavioral responses. Slow firing changes terminate with reinforcers and possibly with auditory stimuli and behavioral responses. A necessary condition for the emergence of slow firing changes seems to be that subjects have learnt that consecutive sensory or behavioral events are contingent on reinforcement. They disappear when the contingencies are no longer present. Slow firing changes in auditory cortex bear similarities with slow changes of neuronal activity that have been observed in subcortical parts of the auditory system and in other non-sensory brain structures. We propose that slow firing changes in auditory cortex provide a neuronal mechanism for anticipating, memorizing, and associating events that are related to hearing and of behavioral relevance. This may complement the representation of the timing and types of auditory and auditory-related events which may be provided by phasic responses in auditory cortex. The presence of slow firing changes indicates that many more auditory-related aspects of a behavioral procedure are reflected in the neuronal activity of auditory cortex than previously assumed. © 2010 Elsevier B.V.

Brosch M.,Leibniz Institute For Neurobiologie | Budinger E.,Leibniz Institute For Neurobiologie | Scheich H.,Leibniz Institute For Neurobiologie
Journal of Cognitive Neuroscience | Year: 2013

Synchronized neuronal firing in cortex has been implicated in feature binding, attentional selection, and other cognitive processes. This study addressed the question whether different cortical fields are distinct by rules according to which neurons engage in synchronous firing. To this end, we simultaneously recorded the multiunit firing at several sites within the primary and the caudomedial auditory cortical field of anesthetized macaque monkeys, determined their responses to pure tones, and calculated the cross-correlation function of the spontaneous firing of pairs of units. In the primary field, the likelihood of synchronous firing of pairs of units increased with the similarity of their frequency tuning and their response latencies. In the caudomedial field, by contrast, the likelihood of synchronization was highest when pairs of units had an octave and other harmonic relationships and when units had different response latencies. The differences in synchrony of the two fields were not paralleled by differences in distributions of best frequency, bandwidth of tuning curves, and response latency. Our findings suggest that neuronal synchrony in different cortical fields may underlie the establishment of specific relationships between the sound features that are represented by the firing of the neurons and which follow the Gestalt laws of similarity in the primary field and good continuation in the caudomedial field. © 2013 Massachusetts Institute of Technology.

Noesselt T.,Otto Von Guericke University of Magdeburg | Tyll S.,Otto Von Guericke University of Magdeburg | Boehler C.N.,Otto Von Guericke University of Magdeburg | Budinger E.,Otto Von Guericke University of Magdeburg | And 4 more authors.
Journal of Neuroscience | Year: 2010

Combining information across modalities can affect sensory performance. We studied how co-occurring sounds modulate behavioral visual detection sensitivity (d′), and neural responses, for visual stimuli of higher or lower intensity. Co-occurrence of a sound enhanced human detection sensitivity for lower- but not higher-intensity visual targets. Functional magnetic resonance imaging (fMRI) linked this to boosts in activity-levels for sensory-specific visual and auditory cortex, plus multisensory superior temporal sulcus (STS), specifically for a lower-intensity visual event when paired with a sound. Thalamic structures in visual and auditory pathways, the lateral and medial geniculate bodies, respectively (LGB, MGB), showed a similar pattern. Subject-by-subject psychophysical benefits correlated with corresponding fMRI signals in visual, auditory, and multisensory regions. We also analyzed differential "coupling" patterns of LGB and MGB with other regions in the different experimental conditions. Effective-connectivity analyses showed enhanced coupling of sensory-specific thalamic bodies with the affected cortical sites during enhanced detection of lower-intensity visual events paired with sounds. Coupling strength between visual and auditory thalamus with cortical regions, including STS, covaried parametrically with the psychophysical benefit for this specific multisensory context. Our results indicate that multisensory enhancement of detection sensitivity for low-contrast visual stimuli by co-occurring sounds reflects a brain network involving not only established multisensory STS and sensoryspecific cortex but also visual and auditory thalamus. Copyright © 2010 the authors.

Viola H.,CONICET | Viola H.,University of Buenos Aires | Ballarini F.,CONICET | Martinez M.C.,CONICET | And 2 more authors.
Progress in Molecular Biology and Translational Science | Year: 2014

The synaptic tagging and capture theory (STC) was postulated by Frey and Morris in 1997 and provided a strong framework to explain how to achieve synaptic specificity and persistence of electrophysiological-induced plasticity changes. Ten years later, the same argument was applied on learning and memory models to explain the formation of long-term memories, resulting in the behavioral tagging hypothesis (BT). These hypotheses are able to explain how a weak event that induces transient changes in the brain can establish long-lasting phenomena through a tagging and capture process. In this framework, it was postulated that the weak event sets a tag that captures plasticity-related proteins/products (PRPs) synthesized by an independent strong event. The tagging and capture processes exhibit symmetry, and therefore, PRPs can be captured if they are synthesized either before or after the setting of the tag. In summary, the hypothesis provides a wide framework that gives a solid explanation of how lasting changes occur and how the interaction between different events leads to promotion, reinforcement, or impairment of such changes. In this chapter, we will summarize the postulates of STC hypothesis, the common features between synaptic plasticity and memory, as well as a detailed compilation of the findings supporting the existence of BT process. At the end, we pose some questions related to BT mechanism and LTM formation, which probably will be answered in the near future. © 2014 Elsevier Inc.

Brosch M.,Leibniz Institute For Neurobiologie | Selezneva E.,Leibniz Institute For Neurobiologie | Scheich H.,Leibniz Institute For Neurobiologie
European Journal of Neuroscience | Year: 2015

This study aimed at a deeper understanding of which cognitive and motivational aspects of tasks affect auditory cortical activity. To this end we trained two macaque monkeys to perform two different tasks on the same audiovisual stimulus and to do this with two different sizes of water rewards. The monkeys had to touch a bar after a tone had been turned on together with an LED, and to hold the bar until either the tone (auditory task) or the LED (visual task) was turned off. In 399 multiunits recorded from core fields of auditory cortex we confirmed that during task engagement neurons responded to auditory and non-auditory stimuli that were task-relevant, such as light and water. We also confirmed that firing rates slowly increased or decreased for several seconds during various phases of the tasks. Responses to non-auditory stimuli and slow firing changes were observed during both the auditory and the visual task, with some differences between them. There was also a weak task-dependent modulation of the responses to auditory stimuli. In contrast to these cognitive aspects, motivational aspects of the tasks were not reflected in the firing, except during delivery of the water reward. In conclusion, the present study supports our previous proposal that there are two response types in the auditory cortex that represent the timing and the type of auditory and non-auditory elements of a auditory tasks as well the association between elements. © 2015 Federation of European Neuroscience Societies and John Wiley and Sons Ltd.

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