The influence of stimulus and behavioral histories on predictive control of smooth pursuit eye movements

The pursuit system has the ability to perform predictive control of eye movements. Even when the target motion is unpredictable due to velocity or direction changes, preceding changes in eye velocity are generated based on weighted averaging of past stimulus timing. However, it is still uncertain whether behavioral history influences the control of predictive pursuit. Thus, we attempted to clarify the influences of stimulus and behavioral histories on predictive pursuit to randomized target velocity. We used alternating-ramp stimuli, where the rightward velocity was fixed while the leftward velocity was either fixed (predictable) or randomized (unpredictable). Predictive eye deceleration was observed regardless of whether the target velocity was predictable or not. In particular, the predictable condition showed that the predictive pursuit responses corresponded to future target velocity. The linear mixed-effects model showed that both stimulus and behavioral histories of the previous two or three trials had influences on the predictive pursuit responses to the unpredictable target velocity. Our results suggest that the predictive pursuit system allows to track randomized target motion using the information from previous several trials, and the information of sensory input (stimulus) and motor output (behavior) in the past time sequences have partially different influences on predictive pursuit.

Prefrontal cortex represents heuristics that shape choice bias and its integration into future behavior

SummaryGoal-directed behavior requires integrating sensory information with prior knowledge about the environment. Behavioral biases that arise from these priors could increase positive outcomes when the priors match the true structure of the environment, but mismatches also happen frequently and could cause unfavorable outcomes. Biases that reduce gains and fail to vanish with training indicate fundamental suboptimalities arising from ingrained heuristics of the brain. Here, we report systematic, gain-reducing choice biases in highly-trained monkeys performing a motion direction discrimination task where only the current stimulus is behaviorally relevant. The monkey’s bias fluctuated at two distinct time scales: slow, spanning tens to hundreds of trials, and fast, arising from choices and outcomes of the most recent trials. Our finding enabled single trial prediction of biases, which influenced the choice especially on trials with weak stimuli. The pre-stimulus activity of neuronal ensembles in the monkey prearcuate gyrus represented these biases as an offset along the decision axis in the state space. This offset persisted throughout the stimulus viewing period, when sensory information was integrated, leading to a biased choice. The pre-stimulus representation of history-dependent bias was functionally indistinguishable from the neural representation of upcoming choice before stimulus onset, validating our model of single-trial biases and suggesting that pre-stimulus representation of choice could be fully defined by biases inferred from behavioral history. Our results indicate that the prearcuate gyrus reflects intrinsic heuristics that compute bias signals, as well as the mechanisms that integrate them into the oculomotor decision-making process.

Apples to apples? Neural correlates of emotion regulation differences between high- and low-risk adolescents

Adolescence has been noted as a period of increased risk taking. The literature on normative neurodevelopment implicates aberrant activation of affective and regulatory regions as key to inhibitory failures. However, many of these studies have not included adolescents engaging in high rates of risky behavior, making generalizations to the most at-risk populations potentially problematic. We conducted a comparative study of nondelinquent community (n = 24, mean age = 15.8 years, 12 female) and delinquent adolescents (n = 24, mean age = 16.2 years, 12 female) who completed a cognitive control task during functional magnetic resonance imaging, where behavioral inhibition was assessed in the presence of appetitive and aversive socioaffective cues. Community adolescents showed poorer behavioral regulation to appetitive relative to aversive cues, whereas the delinquent sample showed the opposite pattern. Recruitment of the inferior frontal gyrus, medial prefrontal cortex, and tempoparietal junction differentiated community and high-risk adolescents, as delinquent adolescents showed significantly greater recruitment when inhibiting their responses in the presence of aversive cues, while the community sample showed greater recruitment when inhibiting their responses in the presence of appetitive cues. Accounting for behavioral history may be key in understanding when adolescents will have regulatory difficulties, highlighting a need for comparative research into normative and nonnormative risk-taking trajectories.

Probabilistic Models of Larval Zebrafish Behavior: Structure on Many Scales

Nervous systems have evolved to combine environmental information with internal state to select and generate adaptive behavioral sequences. To better understand these computations and their implementation in neural circuits, natural behavior must be carefully measured and quantified. Here, we collect high spatial resolution video of single zebrafish larvae swimming in a naturalistic environment and develop models of their action selection across exploration and hunting. Zebrafish larvae swim in punctuated bouts separated by longer periods of rest called interbout intervals. We take advantage of this structure by categorizing bouts into discrete types and representing their behavior as labeled sequences of bout-types emitted over time. We then construct probabilistic models – specifically, marked renewal processes – to evaluate how bout-types and interbout intervals are selected by the fish as a function of its internal hunger state, behavioral history, and the locations and properties of nearby prey. Finally, we evaluate the models by their predictive likelihood and their ability to generate realistic trajectories of virtual fish swimming through simulated environments. Our simulations capture multiple timescales of structure in larval zebrafish behavior and expose many ways in which hunger state influences their action selection to promote food seeking during hunger and safety during satiety.

Apples to apples? Neural correlates of emotion regulation differences between high and low risk adolescents

Adolescence has been noted as a period of increased risk taking. The literature on normative neurodevelopment implicates aberrant activation of affective and regulatory regions as key to inhibitory failures. However, many of these studies have not included adolescents engaging in high rates of risky behavior, making generalizations to the most at-risk populations potentially problematic. We conducted a comparative study of non-delinquent community (N=24, Mage = 15.8 years, 12 female) and delinquent adolescents (N=24, Mage = 16.2 years, 12 female) who completed a cognitive control task during fMRI, where behavioral inhibition was assessed in the presence of appetitive and aversive socioaffective cues. Community adolescents showed poorer behavioral regulation to appetitive relative to aversive cues, whereas the delinquent sample showed the opposite pattern. Recruitment of the inferior frontal gyrus, medial prefrontal cortex, and tempoparietal junction differentiated community and high-risk adolescents, as delinquent adolescents showed significantly greater recruitment when inhibiting their responses in the presence of aversive cues, while the community sample showed greater recruitment when inhibiting their responses in the presence of appetitive cues. Accounting for behavioral history may be key in understanding when adolescents will have regulatory difficulties, highlighting a need for comparative research into normative and non-normative risk-taking trajectories.

Do School Discipline Policies Treat Students Fairly? Evidence From Arkansas

It is well documented that Black students are more likely to receive expulsions and suspensions than their White peers. These disparities are troubling, but researchers and policy makers need more information to fully understand the issue. We use 3 years (2010-2011 through 2012-2013) of state-wide student- and discipline incident-level data to assess whether non-White students are receiving harsher disciplinary consequences than their White peers for similar infractions and with similar behavioral history. We find that Black students received more severe (longer) punishments than their White peers for the same types of infractions, but that these disproportionalities are primarily across rather than within schools.

Feather picking / self-mutilating in psittacine birds. Recent data for the control

Feather picking /self-mutilating is the most frequent and serious problem of psittacine birds that the avian practitioners have to deal with in practice. The etiologic agents of this behavior may be infectious, parasitic, nutritional, but the most interesting among them are psychological (housing, environment, attention seeking etc). It is very difficult to establish accurate diagnosis, although some laboratory examinations may be helpful. Especially the behavioral history may be important for the identification of psychological causatives. Therapy of feather picking is not always possible. Pharmaceutical treatment, primarily with psychotropic drugs, improvement of the housing conditions and nutrition, closer relationship with the persons that the birds live with, may be useful to reduce or even to solve this problem. The prognosis is circumspect, because sometimes, in spite of the therapy, there is no improvement or it is temporary. Feather picking disorder is described in the present study. Recent data on the causative agents and the control of the disorder are also reported.

Tunneled Catheter Placement in a Pediatric Patient: A Novel Approach

Establishing venous access can be an important and often complex aspect of care for pediatric patients. When stable central venous access is required for long-term intravenous infusions, several options are available including peripherally inserted central catheters (PICC), tunneled catheters and ports. Both PICC placement and tunneled catheter placement include an exposed external segment of catheter, either in an extremity or on the chest. We present a pediatric patient with complex behavioral history who required long-term intravenous therapy. After careful review, the best option for the patient was determined to be a tunneled catheter that exited the skin in the right upper back, making it difficult to grab and pull out. The catheter was successfully placed and the patient appropriately completed his intravenous antibiotic course. Upon completion, the catheter was removed without complications. This tunneling technique to the scapular region may be useful for patients with psychiatric or neurodegenerative disorders where purposeful dislodgement may be a problem.