The coming years are likely to be turbulent due to a myriad of factors or polycrisis, including an escalation in climate extremes, emerging public health threats, weak productivity, increases in global economic instability and further weakening in the integrity of global democracy. These formidable challenges are not exogenous to the economy but are in some cases generated by the system itself. They can be overcome, but only with far-reaching changes to global economics.
View Article and Find Full Text PDFEarly sensory relay circuits in the vertebrate medulla often adopt a cerebellum-like organization specialized for comparing primary afferent inputs with central expectations. These circuits usually have a dual output, carried by center ON and center OFF neurons responding in opposite ways to the same stimulus at the center of their receptive fields. Here, we show in the electrosensory lateral line lobe of Gymnotiform weakly electric fish that basilar pyramidal neurons, representing 'ON' cells, and non-basilar pyramidal neurons, representing 'OFF' cells, have different intrinsic electrophysiological properties.
View Article and Find Full Text PDFAdult neurogenesis, an essential mechanism of brain plasticity, enables brain development along postnatal life, constant addition of new neurons, neuronal turnover, and/or regeneration. It is amply distributed but negatively modulated during development and along evolution. Widespread cell proliferation, high neurogenic, and regenerative capacities are considered characteristics of teleost brains during adulthood.
View Article and Find Full Text PDFThe anatomical organization of African Mormyrids' brain is a clear example of departure from the average brain morphotype in teleosts, probably related to functional specialization associated to electrosensory processing and sensory-motor coordination. The brain of Mormyrids is characterized by a well-developed rhombencephalic electrosensory lobe interconnected with relatively large mesencephalic torus semicircularis and optic tectum, and a huge and complex cerebellum. This unique morphology might imply cell addition from extraventricular proliferation zones up to late developmental stages.
View Article and Find Full Text PDFProliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described.
View Article and Find Full Text PDFTeleosts are a numerous and diverse group of fish showing great variation in body shape, ecological niches and behaviors, and a correspondent diversity in brain morphology, usually associated with their functional specialization. Weakly electric fish are a paradigmatic example of functional specialization, as these teleosts use self-generated electric fields to sense the nearby environment and communicate with conspecifics, enabling fish to better exploit particular ecological niches. We analyzed the development of the brain of the pulse type gymnotid Gymnotus omarorum, focusing on the brain regions involved directly or indirectly in electrosensory information processing.
View Article and Find Full Text PDFThis article deals with the electric organ and its discharge in Gymnotus coropinae, a representative species of one of the three main clades of the genus. Three regions with bilateral symmetry are described: (1) subopercular (medial and lateral columns of complex shaped electrocytes); (2) abdominal (medial and lateral columns of cuboidal and fusiform electrocytes); and (3) main [four columns, one dorso-lateral (containing fusiform electrocytes) and three medial (containing cuboidal electrocytes)]. Subopercular electrocytes are all caudally innervated whereas two of the medial subopercular ones are also rostrally innervated.
View Article and Find Full Text PDFWeakly electric fishes "electrically illuminate" the environment in two forms: pulse fishes emit a succession of discrete electric discharges while wave fishes emit a continuous wave. These strategies are present in both taxonomic groups of weakly electric fishes, mormyrids and gymnotids. As a consequence one can distinguish four major types of active electrosensory strategies evolving in parallel.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
November 2008
Pulse gymnotids extract information about the environment using the pulsed discharge of an electric organ. Cutaneous electroreceptor organs transduce and encode the changes that objects imprint on the self-generated transcutaneous electric field. This review deals with the role of a neural circuit, the fast electrosensory path of pulse gymnotids, in the streaming of self generated electrosensory signals.
View Article and Find Full Text PDFSome fish emit electric fields generated by the coordinated activation of electric organs. Such discharges are used for exploring the environment and for communication. This article deals with the development of the electric organ and its discharge in Gymnotus, a pulse genus in which brief discharges are separated by regular silent intervals.
View Article and Find Full Text PDFOne difficulty in understanding the brain is that of linking the structure of the neurons with their computational roles in neural circuits. In this paper we address this subject in a relative simple system, the fast electrosensory pathway of an electric fish, where sensory images are coded by the relative latency of a volley of single spikes. The main input to this path is a stream of discrete electric images resulting from the modulation of a self-generated carrier by the environment.
View Article and Find Full Text PDFConstraints introduced by signal carriers, pre-receptor mechanisms and receptor transduction are fundamental for shaping the signals used by the brain to build up perceptual images. This review analyses some of these constraints in the electrosensory system of pulse Gymnotids. First, it describes the characteristics and differences of electrolocation and electrocommunication carriers.
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