Structural plasticity and associative memory in balanced neural networks with spike-time dependent inhibitory plasticity

Peer reviewe

A system for controlling vocal communication networks

Animal vocalizations serve a wide range of functions including territorial defense, courtship, social cohesion, begging, and vocal learning. Whereas many insights have been gained from observational studies and experiments using auditory stimulation, there is currently no technology available for the selective control of vocal communication in small animal groups. We developed a system for real-time control of vocal interactions among separately housed animals. The system is implemented on a field-programmable gate array (FPGA) and it allows imposing arbitrary communication networks among up to four animals. To minimize undesired transitive sound leakage, we adopted echo attenuation and sound squelching algorithms. In groups of three zebra finches, we restrict vocal communication in circular and in hierarchical networks and thereby mimic complex eavesdropping and middleman situations

Undirected singing rate as a non-invasive tool for welfare monitoring in isolated male zebra finches

Research on the songbird zebra finch (Taeniopygia guttata) has advanced our behavioral, hormonal, neuronal, and genetic understanding of vocal learning. However, little is known about the impact of typical experimental manipulations on the welfare of these birds. Here we explore whether the undirected singing rate can be used as an indicator of welfare. We tested this idea by performing a post hoc analysis of singing behavior in isolated male zebra finches subjected to interactive white noise, to surgery, or to tethering. We find that the latter two experimental manipulations transiently but reliably decreased singing rates. By contraposition, we infer that a high-sustained singing rate is suggestive of successful coping or improved welfare in these experiments. Our analysis across more than 300 days of song data suggests that a singing rate above a threshold of several hundred song motifs per day implies an absence of an acute stressor or a successful coping with stress. Because singing rate can be measured in a completely automatic fashion, its observation can help to reduce experimenter bias in welfare monitoring. Because singing rate measurements are non-invasive, we expect this study to contribute to the refinement of the current welfare monitoring tools in zebra finches.Fil: Yamahachi, Homare. Universitat Zurich; SuizaFil: Zai, Anja T.. Universitat Zurich; SuizaFil: Tachibana, Ryosuke O.. Universitat Zurich; SuizaFil: Stepien, Anna E.. Universitat Zurich; SuizaFil: Rodrigues, Diana I.. Universitat Zurich; SuizaFil: Cavé Lopez, Sophie. Universitat Zurich; SuizaFil: Lorenz, Corinna. Universite Paris Saclay; Francia. Universitat Zurich; SuizaFil: Arneodo, Ezequiel Matías. Universitat Zurich; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Giret, Nicolas. Universite Paris Saclay; FranciaFil: Hahnloser, Richard H. R.. Universitat Zurich; Suiz

Axonal Dynamics of Excitatory and Inhibitory Neurons in Somatosensory Cortex

Electrophysiology-delivery of fluorescent viral vectors-and two-photon microscopy were used to demonstrate the rapidity of axonal restructuring of both excitatory and inhibitory neurons in rodent cortical layer II/III following alterations in sensory experience

Growth Rules for the Repair of Asynchronous Irregular Neuronal Networks after Peripheral Lesions

© 2021 Sinha et al. This is an open access article distributed under the terms of the Creative Commons Attribution License. https://creativecommons.org/licenses/by/4.0/Several homeostatic mechanisms enable the brain to maintain desired levels of neuronal activity. One of these, homeostatic structural plasticity, has been reported to restore activity in networks disrupted by peripheral lesions by altering their neuronal connectivity. While multiple lesion experiments have studied the changes in neurite morphology that underlie modifications of synapses in these networks, the underlying mechanisms that drive these changes are yet to be explained. Evidence suggests that neuronal activity modulates neurite morphology and may stimulate neurites to selective sprout or retract to restore network activity levels. We developed a new spiking network model of peripheral lesioning and accurately reproduced the characteristics of network repair after deafferentation that are reported in experiments to study the activity dependent growth regimes of neurites. To ensure that our simulations closely resemble the behaviour of networks in the brain, we model deafferentation in a biologically realistic balanced network model that exhibits low frequency Asynchronous Irregular (AI) activity as observed in cerebral cortex. Our simulation results indicate that the re-establishment of activity in neurons both within and outside the deprived region, the Lesion Projection Zone (LPZ), requires opposite activity dependent growth rules for excitatory and inhibitory post-synaptic elements. Analysis of these growth regimes indicates that they also contribute to the maintenance of activity levels in individual neurons. Furthermore, in our model, the directional formation of synapses that is observed in experiments requires that pre-synaptic excitatory and inhibitory elements also follow opposite growth rules. Lastly, we observe that our proposed structural plasticity growth rules and the inhibitory synaptic plasticity mechanism that also balances our AI network both contribute to the restoration of the network to pre-deafferentation stable activity levels.Peer reviewe

Axons and synaptic boutons are highly dynamic in adult visual cortex

While recent studies of synaptic stability in adult cerebral cortex have focused on dendrites, how much axons change is unknown. We have used advances in axon labeling by viruses and in vivo two-photon microscopy to investigate axon branching and bouton dynamics in primary visual cortex (V1) of adult Macaque monkeys. A nonreplicative adeno-associated virus bearing the gene for enhanced green fluorescent protein (AAV.EGFP) provided persistent labeling of axons, and a custom-designed two-photon microscope enabled repeated imaging of the intact brain over several weeks. We found that large-scale branching patterns were stable but that a subset of small branches associated with terminaux boutons, as well as a subset of en passant boutons, appeared and disappeared every week. Bouton losses and gains were both approximately 7% of the total population per week, with no net change in the overall density. These results suggest ongoing processes of synaptogenesis and elimination in adult V1

Rapid axonal sprouting and pruning accompany functional reorganization in primary visual cortex

The functional architecture of adult cerebral cortex retains a capacity for experience−dependent change. This is seen following focal binocular lesions, which induce rapid changes in receptive field size and position. To follow the dynamics of the circuitry underlying these changes, we imaged the intrinsic long−range horizontal connections within the lesion projection zone (LPZ) in adult macaque primary visual cortex. To image the same axons over time, we combined viral vector−mediated EGFP transfer and two−photon microscopy. The lesion triggered, within the first week, an 2−fold outgrowth of axons toward the center of the LPZ. Over the subsequent month, axonal density declined due to a parallel process of pruning and sprouting but maintained a net increase relative to prelesion levels. The rate of turnover of axonal boutons also increased. The axonal restructuring recapitulates the pattern of exuberance and pruning seen in early development and correlates well with the functional changes following retinal lesion

A Bluetooth-Low-Energy Sensor Node for Acoustic Monitoring of Small Birds

Animals can generate sounds that serve a wide range of vital functions such as to defend themselves or their territories, to attract a partner, to maintain contact with other members of their social group, and to help themselves and their partner/group during navigation. Ethologists are interested in recording and analyzing these sounds, many of which are vocalizations. Advances in sensing and wireless technology permit today acoustic data acquisition and transmission in a wireless manner. In many applications, the wireless sensor needs to be placed on the animal's body and should be unobtrusive, light-weight, small, and long-lasting. This paper presents the design and development of an ultra-low power miniaturized and lightweight wireless sensor node for monitoring captive zebra finches. The node is designed to be worn with minimal effort by small-sized birds to collect, process, and send/receive data to/from a remote host via Bluetooth Low-Energy. The main feature of the developed node is the capability to stream compressed or uncompressed audio and temperature data continuously. Multiple nodes can monitor several birds simultaneously and acquire and transmit high-quality audio streams, one for each bird, with low audio interference. Due to the combination of low-power hardware and software techniques and technologies, the 1.4 g node achieves a lifetime of up to 24 h at 4 kHz sampling rate on a single zinc-air battery. Experimental results on birds confirm the functionality of the developed wireless node and the lifetime benefits of compression

Large-Scale Axonal Reorganization of Inhibitory Neurons following Retinal Lesions

interior, courtyard, 200