Estudio del procesamiento secuencial de información en el contexto de la electrorrecepción a través de técnicas de estimulación en ciclo cerrado

• Autores: Ángel Lareo Fernández
• Directores de la Tesis: Francisco de Borja Rodríguez Ortiz (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2023
• Idioma: español
• Tribunal Calificador de la Tesis: Eduardo Serrano Jerez (presid.) , Irene Elices Ocón (secret.) , Jorge Mejías Palomino (voc.)
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Nervous systems still overpower artificial systems fulfilling a whole set of complex tasks. Plenty of these tasks involve fast and robust processing of sequential information, so understanding the principles governing temporal coding in biology can draw relevant lessons in neuroscience and other fields. Although traditional unidirectional stimulus-response studies have drawn several conclusions in this regard, nervous systems operate in a constant feedback loop with the environment, so closed-loop methods can be applied to address the inherent closed-loop aspects of natural sequential information processing through online stimulation. In this context, the development of novel protocols of general applicability opens up a wide range of new possibilities. Temporal code-driven stimulation (TCDS), a closed-loop method for studying temporal sequences of activity in biological systems, was designed and implemented in this thesis. It adds to a long list of closed-loop stimulation techniques applied in neuroscience research. Particularly, it provides an easy and generalizable method to register, as binary codes, the sequential activity of a living system and trigger stimulus after the detection of predetermined sequences of events (a code). This method has been successfully applied to study weakly electric fish signaling. The properties of the electromotor system of weakly electric fish, which generates electric signals in the water to communicate, enable TCDS to be used to answer questions in the intersection between computational neuroscience and neuroethology. In the case of Gnathonemus petersii, a species of pulse-type weakly electric fish, patterns of sequences of pulse intervals (SPI) ¿with flexible, yet characteristic, temporal structure¿ have been related with behavior. Results from TCDS applied to electroreception using behavioral SPI stimulus showed that distinct responses arose from different triggering codes. According to preliminary results using a sine-wave stimulus, these results hold as long as the stimulation is presented in a closed-loop manner, which could be explained as a response from the system to an artificial social context implemented by TCDS stimulation. TCDS also enables the use of triggering codes with behavioral significance, which is expected to evoke more significant changes in the SPI pattern generation. In order to delve into the specifics of SPI pattern generation, a computational model of the electromotor command circuit was developed. It reproduces SPI patterns as a function of the inputs while keeping the same internal network configuration. The topology of the model is based on a simplified representation of the network with four neuron clusters (nuclei). An initial ad hoc tuned configuration (S-T) was built to reproduce nucleus characteristics and network topology as described by detailed morphological and electrophysiological studies. Then, a genetic algorithm (GA) was developed and applied to automatically tune the model connectivity¿s synaptic parameters. Results show that the set of SPI patterns is consistently reproduced, both for synthetic data and for recorded data. This model can be used as a tool to test novel hypotheses regarding temporal structure in electrogeneration.