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Previous issue date: 2010-02-26 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior === The currently accepted model of sensory processing states that different senses are processed in parallel, and that the activity of specific cortical regions define the sensorial modality perceived by the subject. In this work we used chronic multielectrode extracellular recordings to investigate to which extent neurons in the visual and tactile primary cortices (V1 and S1) of anesthetized rats would respond to sensory modalities not traditionaly associated with these cortices. Visual stimulation yielded 87% of responsive neurons in V1, while 82% of S1 neurons responded to tactile stimulation. In the same stimulation sessions, we found 23% of V1 neurons responding to tactile stimuli and 22% of S1 neurons responding to visual stimuli. Our data supports an increasing body of evidence that indicates the existence multimodal processing in primary sensory cortices. Our data challenge the unimodal sensory processing paradigm, and suggest the need of a reinterpretation of the currently accepted model of cortical hierarchy. === O modelo de processamento sensorial mais aceito atualmente afirma que os sentidos s?o processados em paralelo, e que a atividade de c?rtices sensoriais espec?ficos define a modalidade sens?ria percebida subjetivamente. Neste trabalho utilizamos registros eletrofisiol?gicos cr?nicos de m?ltiplos neur?nios para investigar se neur?nios nos c?rtices prim?rios visual (V1) e t?til (S1) de ratos anestesiados podem responder a est?mulos das modalidades sensoriais n?o associadas tradicionalmente a estes c?rtices. Durante a estimula??o visual, 87% dos neur?nios de V1 foram responsivos, enquanto 82% dos neur?nios de S1 responderam ? estimula??o t?til. Nos mesmos registros, encontramos 23% dos neur?nios de V1 responsivos a est?mulos t?teis e 22% dos neur?nios de S1 responsivos a est?mulos visuais. Nossos dados corroboram uma crescente s?rie de evid?ncias que indica a presen?a de processamento multimodal nos c?rtices sensoriais prim?rios, o que desafia o paradigma do processamento sensorial unimodal e sugere a necessidade de uma reinterpreta??o do modelo de hierarquia cortical atualmente aceito.
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