Avaliação cognitiva e de respostas evocadas auditivas em regime permanente do rato Wistar audiogênico

Abstract

Seizures can cause morphological and functional changes in neural tissue, and may lead to cognitive functions impairment. Among all the comorbidities that can be generated as a consequence of the epileptogenic process, the memory impairment stands out, having a higher prevalence. Thus, this work was developed with the objective to assess the cognitive function in an epileptogenic circuitry, with concomitant recordings of auditory steady state responses (ASSR), using the genetic animal model named: Wistar audiogenic rat (WAR). These animals manifest a tonic-clonic convulsion induced by repeated highintensity sound stimulation involving mesencephalic substrates, as well as limbic seizures, after chronically applied high-intensity stimulation: audiogenic kindling. In order to answer the following hypothesis: "WARs acoustic-limbic facilitation harms auditory associative learning", Wistar rats (n = 82) and WARs (n = 67) were submitted to the following protocols: Sound stimulation followed by immunohistochemical analysis (cFos) to evaluate hyperexcitability; (2) Behavioral tests for locomotor function evaluation; (3) auditory and contextual fear conditioning and (4) new object recognition test. Our electrophysiological and immunohistochemical results suggest that there is a hyperexcitability in the acoustic pathway of WAR. We suggest that acoustic-limbic facilitation in WARs impairs learning on the auditory conditioning fear learning, but benefits the contextual conditioning fear learning. We suggest that this ambiguity of performance is due to the use of different neural circuits to mediate the conditioned responses, as well as the facility to associate the context present on the training day, modulated by WAR's hypersynchronous amygdalar projections