Neural Representations of Post-Decision Accuracy and Reward Expectation in the Caudate Nucleus and Frontal Eye Field.

Performance monitoring that supports ongoing behavioral adjustments is often examined in the context of either choice confidence for perceptual decisions (i.e., "did I get it right?") or reward expectation for reward-based decisions (i.e., "what reward will I receive?"). However, our understanding of how the brain encodes these distinct evaluative signals remains limited because they are easily conflated, particularly in commonly used two-alternative tasks with symmetric rewards for correct choices. Previously we used a motion-discrimination task with asymmetric rewards to identify neural substrates of forming reward-biased perceptual decisions in the caudate nucleus (part of the striatum in the basal ganglia) and the frontal eye field (FEF, in prefrontal cortex). Here we leveraged this task design to partially decouple estimates of accuracy and reward expectation and examine their impacts on subsequent decisions and their representations in those two brain areas. We identified distinguishable representations of these two evaluative signals in individual caudate and FEF neurons, with regional differences in their distribution patterns and time courses. We observed that well-trained monkeys (both sexes) used both evaluative signals, infrequently but consistently, to adjust their subsequent decisions. We found further that these behavioral adjustments had reliable relationships with the neural representations of both evaluative signals in caudate, but not FEF. These results suggest that the cortico-striatal decision network may use diverse evaluative signals to monitor and adjust decision-making behaviors, adding to our understanding of the different roles that the FEF and caudate nucleus play in a diversity of decision-related computations.

Honeycomb: a template for reproducible psychophysiological tasks for clinic, laboratory, and home use

Objective: To improve the ability of psychiatry researchers to build, deploy, maintain, reproduce, and share their own psychophysiological tasks. Psychophysiological tasks are a useful tool for studying human behavior driven by mental processes such as cognitive control, reward evaluation, and learning. Neural mechanisms during behavioral tasks are often studied via simultaneous electrophysiological recordings. Popular online platforms such as Amazon Mechanical Turk (MTurk) and Prolific enable deployment of tasks to numerous participants simultaneously. However, there is currently no task-creation framework available for flexibly deploying tasks both online and during simultaneous electrophysiology. Methods: We developed a task creation template, termed Honeycomb, that standardizes best practices for building jsPsych-based tasks. Honeycomb offers continuous deployment configurations for seamless transition between use in research settings and at home. Further, we have curated a public library, termed BeeHive, of ready-to-use tasks. Results: We demonstrate the benefits of using Honeycomb tasks with a participant in an ongoing study of deep brain stimulation for obsessive compulsive disorder, who completed repeated tasks both in the clinic and at home. Conclusion: Honeycomb enables researchers to deploy tasks online, in clinic, and at home in more ecologically valid environments and during concurrent electrophysiology.

Honeycomb: a template for reproducible psychophysiological tasks for clinic, laboratory, and home use.

OBJECTIVE: To improve the ability of psychiatry researchers to build, deploy, maintain, reproduce, and share their own psychophysiological tasks. Psychophysiological tasks are a useful tool for studying human behavior driven by mental processes such as cognitive control, reward evaluation, and learning. Neural mechanisms during behavioral tasks are often studied via simultaneous electrophysiological recordings. Popular online platforms such as Amazon Mechanical Turk (MTurk) and Prolific enable deployment of tasks to numerous participants simultaneously. However, there is currently no task-creation framework available for flexibly deploying tasks both online and during simultaneous electrophysiology. METHODS: We developed a task creation template, termed Honeycomb, that standardizes best practices for building jsPsych-based tasks. Honeycomb offers continuous deployment configurations for seamless transition between use in research settings and at home. Further, we have curated a public library, termed BeeHive, of ready-to-use tasks. RESULTS: We demonstrate the benefits of using Honeycomb tasks with a participant in an ongoing study of deep brain stimulation for obsessive compulsive disorder, who completed repeated tasks both in the clinic and at home. CONCLUSION: Honeycomb enables researchers to deploy tasks online, in clinic, and at home in more ecologically valid environments and during concurrent electrophysiology.

Frontal eye field and caudate neurons make different contributions to reward-biased perceptual decisions.

Many decisions require trade-offs between sensory evidence and internal preferences. Potential neural substrates include the frontal eye field (FEF) and caudate nucleus, but their distinct roles are not understood. Previously we showed that monkeys' decisions on a direction-discrimination task with asymmetric rewards reflected a biased accumulate-to-bound decision process (Fan et al., 2018) that was affected by caudate microstimulation (Doi et al., 2020). Here we compared single-neuron activity in FEF and caudate to each other and to accumulate-to-bound model predictions derived from behavior. Task-dependent neural modulations were similar in both regions. However, choice-selective neurons in FEF, but not caudate, encoded behaviorally derived biases in the accumulation process. Baseline activity in both regions was sensitive to reward context, but this sensitivity was not reliably associated with behavioral biases. These results imply distinct contributions of FEF and caudate neurons to reward-biased decision-making and put experimental constraints on the neural implementation of accumulation-to-bound-like computations.

The caudate nucleus contributes causally to decisions that balance reward and uncertain visual information.

Our decisions often balance what we observe and what we desire. A prime candidate for implementing this complex balancing act is the basal ganglia pathway, but its roles have not yet been examined experimentally in detail. Here, we show that a major input station of the basal ganglia, the caudate nucleus, plays a causal role in integrating uncertain visual evidence and reward context to guide adaptive decision-making. In monkeys making saccadic decisions based on motion cues and asymmetric reward-choice associations, single caudate neurons encoded both sources of information. Electrical microstimulation at caudate sites during motion viewing affected the monkeys' decisions. These microstimulation effects included coordinated changes in multiple computational components of the decision process that mimicked the monkeys' similarly coordinated voluntary strategies for balancing visual and reward information. These results imply that the caudate nucleus plays causal roles in coordinating decision processes that balance external evidence and internal preferences.

Ongoing, rational calibration of reward-driven perceptual biases.

Decision-making is often interpreted in terms of normative computations that maximize a particular reward function for stable, average behaviors. Aberrations from the reward-maximizing solutions, either across subjects or across different sessions for the same subject, are often interpreted as reflecting poor learning or physical limitations. Here we show that such aberrations may instead reflect the involvement of additional satisficing and heuristic principles. For an asymmetric-reward perceptual decision-making task, three monkeys produced adaptive biases in response to changes in reward asymmetries and perceptual sensitivity. Their choices and response times were consistent with a normative accumulate-to-bound process. However, their context-dependent adjustments to this process deviated slightly but systematically from the reward-maximizing solutions. These adjustments were instead consistent with a rational process to find satisficing solutions based on the gradient of each monkey's reward-rate function. These results suggest new dimensions for assessing the rational and idiosyncratic aspects of flexible decision-making.

Mitochondrial prohibitin and its ubiquitination during spermatogenesis of the swimming crab Charybdis japonica.

It has been proposed that prohibitin (PHB) involved in multiple cellular functions, including cell proliferation, differentiation, apoptosis, senescence and carcinogenesis. Various cellular compartment location of PHB demonstrates its diverse roles. Based on the full-length sequence of PHB gene, we analyzed the deduced amino acid sequence and the predicted protein structure of this gene in the swimming crab Charybdis japonica. It shows that the structure and function of PHB are conservative. The expression level of PHB mRNA and protein in different tissues were analyzed by sqRT-PCR and western blot respectively, which showed its high expression in testis. We then traced PHB protein by immunofluorescence, and we found its diverse distribution in cytoplasm and mitochondria at different stages. We propose that PHB may participate actively in spermatogenic cell anti-apoptosis, cell nucleus distortion as well as acrosome morphogenesis during the spermatogenesis in Charybdis japonica. Furthermore, PHB was found to be ubiquitinated at different levels. Its signal was weak in spermatocytes and Stage 1 spermatids, stronger in stage 2-4 spermatids, and lowest in mature sperm. Our data shows that PHB may mediate the paternal mitochondrial material degradation by ubiquitination. We conclude that PHB is indispensable in the spermatogenesis of the swimming crab Charybdis japonica through different testis developmental stages.

Feasibility of in ovo diffusion tractography in the chick embryo using a dual-cooling technique.

PURPOSE: To evaluate the capability of a dual-cooling technique in suppressing motion artifact and to evaluate the feasibility of the noninvasive muscle fibers tracking using DTI during chick embryonic development. MATERIALS AND METHODS: Fifteen eggs were divided into three groups of 5 eggs each (one group for each imaging sequence), and eggs were imaged every 48 h from incubation day 4; embryos were imaged in ovo using three sequences of varying duration (T1, T2, and DTI). For each sequence, three preprocessing methods were used: no-cooling (NC), single-cooling (SC), and dual-cooling (DC). Two independent observers assessed images for motion artifact. The results of different preprocessing methods used for each sequence were compared by the χ(2) test. The Cohen kappa test was used to assess the interobserver variability. RESULTS: For T1 imaging, motion artifact was adequately suppressed by both SC and DC methods (χ(2) test; P > 0.05). For T2 imaging, motion artifact was also sufficiently suppressed by both SC and DC methods (χ(2) test; P > 0.05) except incubation day 19 (χ(2) test; P < 0.001). For DTI, motion artifact was less with DC than SC after 8 days (χ(2) test; P < 0.05). Hindlimb muscle fibers of chick embryo could be serially evaluated with DTI from 8 days using dual-cooling technique. CONCLUSION: The dual-cooling technique enables DTI of chick embryo in ovo with minimal motion artifact, which permits muscle fiber tracking by DTI during chick embryonic development possible, and can improve the imaging quality of conventional MRI with long duration and those sensitive to motion.

TGF-ß superfamily: how does it regulate testis development.

Testis development is a highly regulated sequence of developmental process that spans from the establishment of germ cell lineage during embryonic development to the periodic wave of spermatogenesis in adulthood. The normal development of testes and the fertility of male animals require specific cell types to respond correctly at a specific time point, the process of which is precisely regulated by various factors. Several members of the transforming growth factor-ß superfamily are shown to be the key mediators. They act as the extracellular ligand of signaling transduction that regulates the proliferation, differentiation, apoptosis and other cell behaviors to help coordinate the physiology of the cells to the overall development of the testis and the organism. This paper reviews the current understanding of some of TGF-ßs' major regulatory roles in the overall process of testis development, analyzes the current studies and their limitations and points out the research areas that need further investigation.