Biology subjects

Romero-Sosa, J. L.

Publications and source records attributed to Romero-Sosa, J. L..

4 recordsLinked to original sources

bioRxiv2024

Neural coding of choice and outcome are modulated by uncertainty in orbitofrontal but not secondary motor cortex

Orbitofrontal cortex (OFC) and secondary motor cortex (M2) are both implicated in flexible reward learning but the conditions that differentially recruit these regions are not fully understood. We imaged calcium activity from single neurons in OFC or M2 during de novo learning of increasingly uncertain reward probability schedules. Predictions of choice were decoded from M2 neurons with high accuracy under all certainty conditions, but were more accurately decoded from OFC neurons under greater uncertainty. The number of choice- and reward-selective neurons was significantly higher in M2 than in OFC across schedules, but these proportions increased across levels of uncertainty only in OFC. Decoding accuracy of choice and outcome was predicted by behavioral strategies Win-Stay and Lose-Shift in OFC, but not M2. We also tested causal involvement of these regions with chemogenetic perturbation as rats learned increasing and then decreasing uncertainty schedules. Whereas inhibition of OFC neurons attenuated learning across all schedules, M2 neurons were found to support learning in the most certain reward schedule. Thus, OFC neurons preferentially encode choices and outcomes that foster a greater reliance on adaptive strategies under uncertainty. This reveals a novel functional heterogeneity within frontal cortex in support of flexible learning.

neuroscience↗

bioRxiv2023

A special role for Anterior Cingulate Cortex, but not Orbitofrontal Cortex or Basolateral Amygdala, in choices involving information

Subjects often are willing to pay a cost for information. In a procedure that promotes paradoxical choices, animals choose between a richer option followed by a cue that is rewarded 50% of the time (No-info) vs a leaner option followed by one of two cues that signal certain outcomes: one always rewarded (100%), and the other never rewarded, 0% (Info). Since decisions involve comparing the subjective value of options after integrating all their features, preference for information may rely on cortico-amygdalar circuitry. To test this, male and female rats were prepared with bilateral inhibitory DREADDs in the anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), basolateral amygdala (BLA), or null virus (control). We inhibited these regions after stable preference was acquired. We found that inhibition of ACC destabilized choice preference in female rats without affecting latency to choose or response rate to cues. A logistic regression fit revealed that the previous choice strongly predicted preference in control animals, but not in female rats following ACC inhibition. The results reveal a causal, sex-dependent role for ACC in decisions involving information.

neuroscience↗

bioRxiv2020

Differential excitability of PV and SST neurons results in distinct functional roles in inhibition stabilization of Up-states

Up-states are the best-studied example of an emergent neural dynamic regime. Computational models based on a single class of inhibitory neurons indicate that Up-states reflect bistable dynamical systems in which positive feedback is stabilized by strong inhibition and predict a paradoxical effect in which increased drive to inhibitory neurons results in decreased inhibitory activity. To date, however, computational models have not incorporated empirically defined properties of PV and SST neurons. Here we first, experimentally characterized the frequencycurrent (F-I) curves of pyramidal, PV, and SST neurons and confirmed a sharp difference between the threshold and slopes of PV and SST neurons. The empirically defined F-I curves were incorporated into a three-population computational model that simulated the empirically-derived firing rates of pyramidal, PV, and SST neurons. Simulations revealed that the intrinsic properties were sufficient to predict that PV neurons are primarily responsible for generating the nontrivial fixed points representing Up-states. Simulations and analytical methods demonstrated that while the paradoxical effect is not obligatory in a model with two classes of inhibitory neurons, it is present in most regimes. Finally, experimental tests validated predictions of the model that the Pyr{leftrightarrow}PV inhibitory loop is stronger than the Pyr{leftrightarrow}SST loop. SIGNIFICANCE STATEMENTMany cortical computations, such as working memory, rely on the local recurrent excitatory connections that define cortical circuit motifs. Up-states are among the simplest and best studied examples of neural dynamic regimes that rely on recurrent excitatory excitation. However, this positive feedback must be held in check by inhibition. To address the relative contribution of PV and SST neurons we characterized the intrinsic input-output differences between these classes of inhibitory neurons, and using experimental and theoretical methods show that the higher threshold and gain of PV leads to a dominant role in network stabilization.

neuroscience↗

bioRxiv2019

Musical expertise generalizes to superior temporal scaling in a Morse code tapping task

A key feature of the brains ability to tell time and generate complex temporal patterns is its capacity to produce similar temporal patterns at different speeds. For example, humans can tie a shoe, type, or play an instrument at different speeds or tempi--a phenomenon referred to as temporal scaling. While it is well established that training improves timing precision and accuracy, it is not known whether expertise improves temporal scaling. We quantified temporal scaling and timing precision in musicians and non-musicians as they learned to tap a Morse code sequence. We found that controls improved significantly over the course of days of training at the standard speed. In contrast, musicians exhibited a high level of temporal precision on the first day, which did not improve significantly with training. Although there was no significant difference in performance at the end of training at the standard speed, musicians were significantly better at temporal scaling--i.e., at reproducing the learned Morse code pattern at faster and slower speeds. Interestingly, both musicians and non-musicians exhibited a Weber-speed effect, where absolute temporal precision sharpened when producing patterns at the faster speed. These results are the first to establish that the ability to generate the same motor patterns at different speeds improves with extensive training and generalizes to non-musical domains.

neuroscience↗