Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-11-25T21:10:57Z No. of bitstreams: 1 JulianaMartinsDeAssis_DISSERT.pdf: 42758575 bytes, checksum: c413d7ee5565791b44bbb59e044748ab (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2015-11-25T22:48:32Z (GMT) No. of bitstreams: 1 JulianaMartinsDeAssis_DISSERT.pdf: 42758575 bytes, checksum: c413d7ee5565791b44bbb59e044748ab (MD5) / Made available in DSpace on 2015-11-25T22:48:32Z (GMT). No. of bitstreams: 1 JulianaMartinsDeAssis_DISSERT.pdf: 42758575 bytes, checksum: c413d7ee5565791b44bbb59e044748ab (MD5) Previous issue date: 2014-07-03 / O processo de codifica??o ? um aspecto fundamental do funcionamento cerebral. A transforma??o de est?mulos sensoriais em respostas neurofisiol?gicas tem sido objeto de estudo em diversas ?reas da Neuroci?ncia. Um dos modos mais utilizados para medir a efici?ncia de um c?digo neural ? pelo uso de medidas advindas da Teoria da Informa??o, como a informa??o m?tua. Utilizando estas ferramentas, estudos recentes mostraram que no c?rtex auditivo tanto registros de potenciais de campo local (LFPs - local field potentials) quanto os tempos de disparos de potenciais de a??o codificam informa??o sobre est?mulos sonoros. Todavia, n?o h? estudos aplicando ferramentas da Teoria da Informa??o para investigar a efici?ncia de c?digos que utilizem potenciais p?s-sin?pticos (PSPs - postsynaptics potentials), isoladamente e em conjunto com an?lises de LFPs. Estes sinais est?o relacionados visto que os LFPs s?o em parte constru?dos pela a??o conjunta de v?rios PSPs. A presente disserta??o reporta medidas de informa??o m?tua entre respostas de PSPs e LFPs obtidas no c?rtex auditivo prim?rio de ratos anestesiados e est?mulos sonoros de frequ?ncias distintas. Nossos resultados mostram que respostas de PSPs possuem informa??o sobre est?mulos sonoros, em n?veis compar?veis e mesmo maiores que as respostas de LFPs. Tamb?m encontramos que PSPs e LFPs codificam informa??o sonora independentemente, uma vez que a an?lise conjunta destes sinais n?o mostrou sinergia nem redund?ncia / Coding process is a fundamental aspect of cerebral functioning. The sensory stimuli transformation in neurophysiological responses has been a research theme in several areas of Neuroscience. One of the most used ways to measure a neural code e ciency is by the use of Information Theory measures, such as mutual information. Using these tools, recent studies show that in the auditory cortex both local eld potentials (LFPs) and action potential spiking times code information about sound stimuli. However, there are no studies applying Information Theory tools to investigate the e ciency of codes that use postsynaptics potentials (PSPs), alone and associated with LFP analysis. These signals are related in the sense that LFPs are partly created by joint action of several PSPs. The present dissertation reports information measures between PSP and LFP responses obtained in the primary auditory cortex of anaesthetized rats and auditory stimuli of distinct frequencies. Our results show that PSP responses hold information about sound stimuli in comparable levels and even greater than LFP responses. We have also found that PSPs and LFPs code sound information independently, since the joint analysis of these signals did neither show synergy nor redundancy.