Neural Mechanisms of Selective Auditory Attention in Rats (Dissertation)

Abstract

of the Dissertation Neural Mechanisms of Selective Auditory Attention in Rats by Lung-Hao Tai Doctor of Philosophy in Neuroscience Stony Brook University 2008How does attention modulate sensory representations? In order to probe the underlying neural mechanisms, we established a simple rodent model of modality-specific attention. Rats were trained to perform distinct auditory two-tone discrimination and olfactory odor discrimination in a two alternative choice (2AC) paradigm.To determine auditory cortex's role in this frequency discrimination task, we used GABA-A receptor agonist muscimol to transiently and reversibly inactivate auditory cortexes bilaterally in rats performing simple interleaved auditory and olfactory discrimination. With olfactory discrimination performance serving as internal control for motivation and decision making capability, we found only auditory two-tone

Engaging in an auditory task suppresses responses in auditory cortex

“…3), in which target stimuli were similarly sub-optimal, no widespread suppression was observed when the auditory stimulus was selectively attended. Intermodal attention enhanced responses in some auditory cortical neurons and suppressed it in others 2220 , but it did not generate the large population effects observed in task-engaged suppression. Second, suppression resulting from engagement was general, for both target and non-target stimulus, and appeared independent of neural selectivity; responses selective for the location of the sound were not preferentially enhanced during the sound localization task (Fig.…”

“…Indeed, there was a slight, albeit nonsignificant, trend toward enhancement in the auditory block, as expected from recordings in an auditory area during an auditory task. A subset of single neurons showed strong modulation (either positive or negative) between the auditory and olfactory blocks, so that the very small net change between the blocks reflected a balance between the changes in the two conditions ( not shown; see 22 ). These results are inconsistent with the hypothesis that engaging in an auditory task per se suppresses responses in auditory cortex, and support the interpretation advanced above that suppression results from engaging in a task, regardless of sensory modality.…”

The auditory cortex mediates the perceptual effects of acoustic temporal expectation

“…3a). Using a similar behavioral paradigm, we have previously shown that muscimol inactivation of the auditory cortex impairs auditory performance on a simple auditory discrimination task but has no effect on an olfactory discrimination task 11 .…”