Biology subjects

Funamizu, A.

Publications and source records attributed to Funamizu, A..

3 recordsLinked to original sources

bioRxiv2024

Global neural encoding of model-free and inference-based strategies in mice

When a simple model-free strategy does not provide sufficient outcomes, an inference-based strategy estimating a hidden task structure becomes essential for optimizing choices. However, the neural circuitry involved in inference-based strategies is still unclear. We developed a tone frequency discrimination task in head-fixed mice in which the tone category of the current trial depended on the category of the previous trial. When the tone category was repeated every trial, the mice continued to use the default model-free strategy, as well as when tone was randomly presented, to bias the choices. In contrast, the default strategy gradually shifted to an inference-based strategy when the tone category was alternated in each trial. Brain-wide electrophysiological recording during the overtrained phase suggested that the neural activity of the frontal and sensory cortices, hippocampus, and striatum was correlated with the reward expectation of both the model-free and inference-based strategies. These results suggest the global encoding of multiple strategies in the brain.

neuroscience↗

bioRxiv2023

Localized and global computation for integrating prior value and sensory evidence in the mouse cerebral cortex

Adaptive behavior requires integrating prior knowledge of action outcomes and sensory evidence for making decisions while maintaining prior knowledge for future actions. As outcome- and sensory-based decisions are often tested separately, it is unclear how these processes are integrated in the brain. In a tone frequency discrimination task with two sound durations and asymmetric reward blocks, we found that neurons in the medial prefrontal cortex of male mice represented the additive combination of prior reward expectations and choices. The sensory inputs and choices were selectively decoded from the auditory cortex irrespective of reward priors and the secondary motor cortex, respectively, suggesting localized computations of task variables are required within single trials. In contrast, all the recorded regions represented prior values that needed to be maintained across trials. We propose localized and global computations of task variables in different time scales in the cerebral cortex.

neuroscience↗

bioRxiv2023

Stable sound decoding despite modulated sound representation in the auditory cortex

The activity of neurons in the auditory cortex is driven by both sounds and non-sensory context. To investigate the neuronal correlates of non-sensory context, we trained head-fixed mice to perform a two-alternative choice auditory task in which either reward or stimulus expectation (prior) was manipulated in blocks. Using two-photon calcium imaging to record populations of single neurons in auditory cortex, we found that both stimulus and reward expectation modulated the activity of these neurons. A linear decoder trained on this population activity could decode stimuli as well or better than predicted by the animals performance. Interestingly, the optimal decoder was stable even in the face of variable sensory representations. Neither the context nor the mouses choice could be reliably decoded from the recorded neural activity. Our findings suggest that in spite of modulation of auditory cortical activity by task priors, auditory cortex does not represent sufficient information about these priors to exploit them optimally and that decisions in this task require that rapidly changing sensory information be combined with more slowly varying task information extracted and represented in brain regions other than auditory cortex.

neuroscience↗