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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.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/19381 |
| Date | 03 July 2014 |
| Creators | Assis, Juliana Martins de |
| Contributors | 96602767020, http://lattes.cnpq.br/3181888189086405, Abreu, Jean Faber Ferreira de, 03203469600, http://lattes.cnpq.br/7024428296425939, Schmidt, Kerstin Erika, 70024141437, http://lattes.cnpq.br/4902752912395893, Tort, Adriano Bretanha Lopes |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM NEUROCI?NCIAS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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