Reciprocal neural connections between the central posterior/prepacemaker nucleus and nucleus G in the gymnotiform fish, Apteronotus leptorhynchus

Control of noise-induced coherent oscillations in three-neuron motifs

The phenomenon of self-induced stochastic resonance (SISR) requires a nontrivial scaling limit between the deterministic and the stochastic timescales of an excitable system, leading to the emergence of coherent oscillations which are absent without noise. In this paper, we numerically investigate SISR and its control in single neurons and three-neuron motifs made up of the Morris–Lecar model. In single neurons, we compare the effects of electrical and chemical autapses on the degree of coherence of the oscillations due to SISR. In the motifs, we compare the effects of altering the synaptic time-delayed couplings and the topologies on the degree of SISR. Finally, we provide two enhancement strategies for a particularly poor degree of SISR in motifs with chemical synapses: (1) we show that a poor SISR can be significantly enhanced by attaching an electrical or an excitatory chemical autapse on one of the neurons, and (2) we show that by multiplexing the motif with a poor SISR to another motif (with a high SISR in isolation), the degree of SISR in the former motif can be significantly enhanced. We show that the efficiency of these enhancement strategies depends on the topology of the motifs and the nature of synaptic time-delayed couplings mediating the multiplexing connections.

Neurotrophins Time Point Intervention after Traumatic Brain Injury: From Zebrafish to Human

Traumatic brain injury (TBI) remains the leading cause of long-term disability, which annually involves millions of individuals. Several studies on mammals reported that neurotrophins could play a significant role in both protection and recovery of function following neurodegenerative diseases such as stroke and TBI. This protective role of neurotrophins after an event of TBI has also been reported in the zebrafish model. Nevertheless, reparative mechanisms in mammalian brain are limited, and newly formed neurons do not survive for a long time. In contrast, the brain of adult fish has high regenerative properties after brain injury. The evident differences in regenerative properties between mammalian and fish brain have been ascribed to remarkable different adult neurogenesis processes. However, it is not clear if the specific role and time point contribution of each neurotrophin and receptor after TBI is conserved during vertebrate evolution. Therefore, in this review, I reported the specific role and time point of intervention for each neurotrophic factor and receptor after an event of TBI in zebrafish and mammals.

Fiber connections of the diencephalic nucleus tuberis anterior in the weakly electric fish,Gymnotus cf. carapo: An in vivo tract-tracing study

Transport of biotinylated dextran amine shows the spatial segregation of mechanosensory afferents in the nucleus tuberis anterior (TA) of a gymnotiform fish, Gymnotus cf. carapo. Only the intermediate subdivision of this nucleus receives projections from the lateral region of the ventral torus semicircularis (TSv), which represents the principal midbrain center for mechanosensory information processing, and from the ventral nucleus praeeminentialis, which receives collaterals of ascending second order mechanosensory fibers that emerge from the mechanosensory lateral line lobe. Considering this aspect, a rostrocaudal subdivision of the TA is proposed. The TA also receives input from regions subserving other sensory modalities, suggesting a role in multisensory interaction. Another important finding of this work consisted in the demonstration of reciprocal connections between the TA and the inferior lobe of the hypothalamus, which is known to receive gustatory, visual, and electrosensory input and is therefore considered a multisensory integration center involved in feeding and aggressive behavior. Furthermore, reciprocal connections between the TA and the preelectromotor central-posterior/prepacemaker complex may provide an access for the processed mechanosensory information to interact with the transient modulations of the electric organ discharge that accompany different behaviors.