Medial Geniculate, Amygdalar and Cingulate Cortical Training-Induced Neuronal Activity during Discriminative Avoidance Learning in Rabbits with Auditory Cortical Lesions

Abstract

This study addressed the neural mediation of discriminative avoidance learning, wherein rabbits step in a wheel apparatus in response to an acoustic conditional stimulus, the CSϩ, to avoid a foot shock, and they learn to ignore a different stimulus, the CSϪ, not followed by foot shock. Previously, muscimolinduced inactivation of the amygdala in the first session of training prevented learning during the inactivation and permanently blocked the development of discriminative traininginduced neuronal activity (TIA) in the medial division of the medial geniculate nucleus (MGm). These results suggested that amygdalar neurons induce discriminative TIA in the MGm via basolateral (BL) amygdalar axonal projections to the auditory cortex. To test this hypothesis, the activity of neurons in the MGm was recorded during learning in rabbits with lesions of the auditory cortex. Recordings were also made in the lateral and BL amygdalar nuclei and in the cingulate cortex. In support of the hypothesis, discriminative learning in rabbits with lesions was impaired significantly during early training sessions 1-4; in these same sessions, discriminative TIA was abolished in the MGm, the BL nucleus, and the anterior cingulate cortex. The lesions also blocked posterior cingulate cortical discriminative TIA in training sessions 1-2 but spared TIA in sessions 3-7. Lateral amygdalar neurons showed gradual development of discrimination that was not significantly affected by the lesions. The results demonstrate a critical role of auditory cortex in early discriminative learning and in the production of early discriminative TIA in multiple areas.

Nicotinic acetylcholine receptors in rat forebrain that bind 18F‐nifene: Relating PET imaging, autoradiography, and behavior

“…In Section 2, we describe the performance of 12 rats trained on an auditory-cognitive task, i.e., auditory-cued active avoidance. Performance on this task is impaired by lesions of auditory cortex (Delay and Rudolph, 1994; Duvel et al, 2001; Ohl et al, 1999), and enhanced by systemic administration of nicotine (Erickson, 1971; Sansone et al, 1994a; Sansone et al, 1994b; Sansone et al, 1991; Yilmaz et al, 1997). Finally, in Section 3, we present 18 F-nifene binding data for six rats—the three best-performing and three worst-performing animals from the cohort in Section 2—in order to correlate performance with binding in selected brain regions.…”

On the interdependence of cognition and emotion

“…The low route has limited capacity for stimulus discrimination. Fear conditioning studies that find support for the low route typically require only detection of the presence or absence of a stimulus (Duvel, Smith, Talk, & Gabriel, 2001;LeDoux et al, 1989;Shi & Davis, 2001). When the task requires discriminating one stimulus from another (e.g., CS+ = high freq.…”

“…tone, CS− = low freq. tone), then cortical analysis appears to be necessary (Butler, Diamond, & Neff, 1957;Duvel et al, 2001;Komura et al, 2001;McCabe, McEchron, Green, & Schneiderman, 1993;Nicholson & Freeman, 2000;Thompson, 1962).…”

Thalamocortical and Corticothalamic Interaction in the Auditory System

“…The MGv and primary CT pathway are believed to carry fast, sensory specific inputs and peripheral tonotopic maps to the AI [114] . The MGm is found to be involved in neuronal plasticity during auditory fear conditioning [115][116][117][118] . Learning in a fear condition is possibly associated with an elevated alertness of the AC and amygdala, where the MGm also sends projections.…”