Auditory thalamus and auditory cortex are equally modulated by context during flexible categorization of sounds.
In a dynamic world, animals must adapt rapidly to changes in the meaning of environmental cues. Such changes can influence the neural representation of sensory stimuli. Previous studies have shown that associating a stimulus with a reward or punishment can modulate neural activity in the auditory cortex (AC) and its thalamic input, the medial geniculate body (MGB). However, it is not known whether changes in stimulus-action associations alone can also modulate neural responses in these areas. We designed a categorization task for rats in which the boundary that separated low- from high-frequency sounds varied several times within a behavioral session, thus allowing us to manipulate the action associated with some sounds without changing the associated reward. We developed a computational model that accounted for the rats' performance and compared predictions from this model with sound-evoked responses from single neurons in AC and MGB in animals performing this task. We found that the responses of 15% of AC neurons and 16% of MGB neurons were modulated by changes in stimulus-action association and that the magnitude of the modulation was comparable between the two brain areas. Our results suggest that the AC and thalamus play only a limited role in mediating changes in associations between acoustic stimuli and behavioral responses.
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.
Santiago
S
Jaramillo
Katharine
K
Borges
Anthony M
AM
Zador
D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D001307:Auditory Perception; D004192:Discrimination, Psychological; D005072:Evoked Potentials, Auditory; D005829:Geniculate Bodies / Q000166:cytology / Q000502:physiology*; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D012201:Reward; D013016:Sound
auditory; categorization; flexibility; reward; stimulus–action association