Neocortical sensory areas have associated primary and secondary thalamic nuclei. While primary nuclei transmit sensory information to cortex, secondary nuclei remain poorly understood. I recorded juxtasomally from the secondary somatosensory (POm) and visual (LP) nuclei of awake mice. POm activity correlated with whisking, but not precise whisker kinematics.
This movement modulation was not a result of sensory reafference, nor was it due to input from motor or somatosensory cortex, nor the superior colliculus. Whisking and pupil dilation were strongly correlated, reflecting arousal. Indeed LP, which is not part of the whisker system, tracked whisking equally well, indicating that POm activity does not encode whisker movement per se. The semblance of movement-related activity is likely instead a global effect of arousal on both nuclei. I then investigated how POm and LP may support feature-based attention.
I trained head-fixed mice to attend to one sensory modality while ignoring a second modality. I used multielectrode arrays to record simultaneously from both regions. In mice trained to respond to tactile stimuli and ignore visual stimuli, POm was robustly activated by touch and largely unresponsive to visual stimuli. The reverse pattern was observed when mice were trained to respond to visual stimuli and ignore touch, with POm now more robustly activated during visual trials. This POm activity was not explained by differences in movements (i.e., whisking, licking) resulting from the two tasks. LP exhibited similar phenomena.
I conclude that behavioral training reshapes activity in secondary thalamic nuclei. Secondary nuclei may respond to behaviorally relevant, reward-predicting stimuli regardless of stimulus modality.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/p241-s079 |
| Date | January 2023 |
| Creators | Petty, Gordon Highsmith |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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