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Lesion-induced insights in the plasticity of the insect auditory system.

Lakes-Harlan R - Front Physiol (2013)

Bottom Line: Transient lesion of the auditory nerve allows us to study regeneration as well as plasticity processes.Interestingly, after regeneration a changed neuronal network will be maintained.These paradigms are now been used to analyze molecular mechanism in neuronal plasticity on the level of single neurons and small networks.

View Article: PubMed Central - PubMed

Affiliation: AG Integrative Sensory Physiology, Institute for Animal Physiology, Justus-Liebig-University Gießen Gießen, Germany.

ABSTRACT
The auditory networks of Orthoptera offer a model system uniquely suited to the study of neuronal connectivity and lesion-dependent neural plasticity. Monaural animals, following the permanent removal of one ear in nymphs or adults, adjust their auditory pathways by collateral sprouting of afferents and deafferented interneurons which connect to neurons on the contralateral side. Transient lesion of the auditory nerve allows us to study regeneration as well as plasticity processes. After crushing the peripheral auditory nerve, the lesioned afferents regrow and re-establish new synaptic connections which are relevant for auditory behavior. During this process collateral sprouting occurs in the central nervous networks, too. Interestingly, after regeneration a changed neuronal network will be maintained. These paradigms are now been used to analyze molecular mechanism in neuronal plasticity on the level of single neurons and small networks.

No MeSH data available.


Related in: MedlinePlus

Schematic drawing of the afferent auditory system of Orthoptera (exemplified for Ensifera). (A) The primary sensory neurons are located in the peripheral ear and project their axons (AFF, afferents) to an auditory neuropile (AN, pink) in the central nervous system (CNS). The afferents synapse onto the dendritic region (red bar) of first order auditory interneurons (1IN). The processing is strictly ipsilateral of the midline (ML). The interneurons could transport the information to the contralateral side (not shown) and/or toward higher centers in the CNS. (B) After a peripheral lesion of the afferents (arrow), the distal part of the axon degenerates (DEG) and regeneration starts at the proximal part (REG). First order interneurons grow collateral sprouts (CS) across the midline into the intact part of the auditory neuropile.
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Figure 1: Schematic drawing of the afferent auditory system of Orthoptera (exemplified for Ensifera). (A) The primary sensory neurons are located in the peripheral ear and project their axons (AFF, afferents) to an auditory neuropile (AN, pink) in the central nervous system (CNS). The afferents synapse onto the dendritic region (red bar) of first order auditory interneurons (1IN). The processing is strictly ipsilateral of the midline (ML). The interneurons could transport the information to the contralateral side (not shown) and/or toward higher centers in the CNS. (B) After a peripheral lesion of the afferents (arrow), the distal part of the axon degenerates (DEG) and regeneration starts at the proximal part (REG). First order interneurons grow collateral sprouts (CS) across the midline into the intact part of the auditory neuropile.

Mentions: Like other neural systems in insects, auditory networks have long been regarded as inflexible neural systems. A main basis for this impression is that in some taxa, like Orthoptera, auditory systems are involved in intraspecific communication whose signals are relatively constant in a population. These acoustic signals facilitate species discrimination which implies reliable neuronal processing of such signals. Orthopteran auditory systems are divers, but they have in common that about 20–80 primary sensory neurons are located in the peripheral ear. The sensory axons project ipsilaterally into a target neuropile in the respective ganglia of the central nervous system (CNS; Figure 1; Stumpner and von Helversen, 2001). Within the neuropile the afferents are monosynaptically connected to individually identifiable first order interneurons. These interneurons process and transmit the information either to the contralateral side or to higher centers in the CNS. The different auditory systems are quite well-known in their anatomy, physiology, and behavior in intact animals, allowing to analyze lesion-induced neuronal plasticity. Two different experiment approaches have been used. Firstly, the information transfer has been interrupted permanently with a removal of one ear. Anatomical, physiological and behavioral analyses show astonishing neuronal plasticity in the auditory system. Secondly, a transient lesion, an axotomy of the auditory afferents has been used to study a combination of regenerative and plasticity processes. Here the results of lesions in auditory systems of Orthoptera are reviewed in respect to the two paradigms and in respect to the first data on molecular mechanisms behind the processes.


Lesion-induced insights in the plasticity of the insect auditory system.

Lakes-Harlan R - Front Physiol (2013)

Schematic drawing of the afferent auditory system of Orthoptera (exemplified for Ensifera). (A) The primary sensory neurons are located in the peripheral ear and project their axons (AFF, afferents) to an auditory neuropile (AN, pink) in the central nervous system (CNS). The afferents synapse onto the dendritic region (red bar) of first order auditory interneurons (1IN). The processing is strictly ipsilateral of the midline (ML). The interneurons could transport the information to the contralateral side (not shown) and/or toward higher centers in the CNS. (B) After a peripheral lesion of the afferents (arrow), the distal part of the axon degenerates (DEG) and regeneration starts at the proximal part (REG). First order interneurons grow collateral sprouts (CS) across the midline into the intact part of the auditory neuropile.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750944&req=5

Figure 1: Schematic drawing of the afferent auditory system of Orthoptera (exemplified for Ensifera). (A) The primary sensory neurons are located in the peripheral ear and project their axons (AFF, afferents) to an auditory neuropile (AN, pink) in the central nervous system (CNS). The afferents synapse onto the dendritic region (red bar) of first order auditory interneurons (1IN). The processing is strictly ipsilateral of the midline (ML). The interneurons could transport the information to the contralateral side (not shown) and/or toward higher centers in the CNS. (B) After a peripheral lesion of the afferents (arrow), the distal part of the axon degenerates (DEG) and regeneration starts at the proximal part (REG). First order interneurons grow collateral sprouts (CS) across the midline into the intact part of the auditory neuropile.
Mentions: Like other neural systems in insects, auditory networks have long been regarded as inflexible neural systems. A main basis for this impression is that in some taxa, like Orthoptera, auditory systems are involved in intraspecific communication whose signals are relatively constant in a population. These acoustic signals facilitate species discrimination which implies reliable neuronal processing of such signals. Orthopteran auditory systems are divers, but they have in common that about 20–80 primary sensory neurons are located in the peripheral ear. The sensory axons project ipsilaterally into a target neuropile in the respective ganglia of the central nervous system (CNS; Figure 1; Stumpner and von Helversen, 2001). Within the neuropile the afferents are monosynaptically connected to individually identifiable first order interneurons. These interneurons process and transmit the information either to the contralateral side or to higher centers in the CNS. The different auditory systems are quite well-known in their anatomy, physiology, and behavior in intact animals, allowing to analyze lesion-induced neuronal plasticity. Two different experiment approaches have been used. Firstly, the information transfer has been interrupted permanently with a removal of one ear. Anatomical, physiological and behavioral analyses show astonishing neuronal plasticity in the auditory system. Secondly, a transient lesion, an axotomy of the auditory afferents has been used to study a combination of regenerative and plasticity processes. Here the results of lesions in auditory systems of Orthoptera are reviewed in respect to the two paradigms and in respect to the first data on molecular mechanisms behind the processes.

Bottom Line: Transient lesion of the auditory nerve allows us to study regeneration as well as plasticity processes.Interestingly, after regeneration a changed neuronal network will be maintained.These paradigms are now been used to analyze molecular mechanism in neuronal plasticity on the level of single neurons and small networks.

View Article: PubMed Central - PubMed

Affiliation: AG Integrative Sensory Physiology, Institute for Animal Physiology, Justus-Liebig-University Gießen Gießen, Germany.

ABSTRACT
The auditory networks of Orthoptera offer a model system uniquely suited to the study of neuronal connectivity and lesion-dependent neural plasticity. Monaural animals, following the permanent removal of one ear in nymphs or adults, adjust their auditory pathways by collateral sprouting of afferents and deafferented interneurons which connect to neurons on the contralateral side. Transient lesion of the auditory nerve allows us to study regeneration as well as plasticity processes. After crushing the peripheral auditory nerve, the lesioned afferents regrow and re-establish new synaptic connections which are relevant for auditory behavior. During this process collateral sprouting occurs in the central nervous networks, too. Interestingly, after regeneration a changed neuronal network will be maintained. These paradigms are now been used to analyze molecular mechanism in neuronal plasticity on the level of single neurons and small networks.

No MeSH data available.


Related in: MedlinePlus