Topic: rhesus monkeys

Serial thinking is a cognitive function underpinning almost any of our daily actions. Our brain continuously encodes and learns ordered sequences that we can remember, process and replay as in motor planning and language production. Despite the pervasiveness of such computation, a full understanding of the neuronal machinery underpinning this function is still lacking. Psychophysical evidence suggests that the ordering of learned information can be solved resorting to a linear mental workspace, namely the mental line, in which the relevant items are mapped according to their arbitrary assigned

Value optimization is a defining principle of economic behavior. To uncover the underlying psychological and neural processes, we developed a behavioral task based on the ‘knapsack problem’. Given several items, each with a value and weight, the objective is to maximize value within the weight limit of the knapsack. Two rhesus monkeys solved a touchscreen-based version that equates weights with juice reward sizes. The animals performed well above chance and achieved at least 75% of the optimal reward value on 80% of all knapsack trials. We defined each unique set of items as an ‘instance,’ and

Increasing the magnitude of an offered reward for an action can improve performance. However, performance can suffer when the payoff is exceptionally large, a phenomenon dubbed “choking under pressure.” What is the neural basis of choking under pressure, and what are the neural mechanisms whereby potential rewards affect motor performance? To study the interaction between rewards and movement, we recorded neural population activity in the motor cortex of rhesus monkeys as they performed a challenging delayed-reaching task, in which the reward available for a successful reach was pre-cued. Bot

When navigating a familiar environment, your behavior may vary depending on your goals. For example, you might take a detour to check out a restaurant you have been curious about, but if you're in a rush, you will opt for the shortest route. Our research focuses on how the brain's neural population, particularly in regions associated with goal-directed behavior (the orbitofrontal cortex, OFC) and navigation (the retrosplenial cortex, RSC), orchestrates the transition between competing goals during navigation. To explore this, we designed a virtual-reality maze task for two Rhesus monkeys, wher

Understanding how the brain encodes movements is vital for motor control. Research suggests that this involves comparing proprioceptive inputs from the body with an internal model of expected movement. When these signals match, vestibular signals---which would otherwise stabilize the head against movements---are suppressed, allowing voluntary movement to occur. This mechanism implies that integrating proprioceptive and vestibular inputs is crucial for effective coordination. While previous studies indicate the involvement of multiple brain areas, with the PIVC at the forefront, the mechanisms

The self-ordered spatial search (SOSS) task is a touchscreen paradigm probing visuospatial working memory (SWM), that can be applied in non-human primate research in a preclinical translational setting. We examined the performance of the animals in the task on control baseline days and after a transient cognitive impairment induced by scopolamine, a muscarinic acetylcholine-receptor antagonist.Fourteen adult male rhesus monkeys performed the SOSS task daily, in 1-hour sessions with 300-500 trials each. In every trial the animals were shown a set of 4-8 identical cyan squares on a touchscreen,

The recent focus on graphene surface electrodes stems from their remarkable sensitivity, biocompatibility, and flexibility, making them a promising avenue for recording and perturbing neuronal activity. This technology holds potential for gaining better insights into cortical networks due to these characteristics. To comprehend local networks of the motor cortex and monitoring network changes during stimulation, we utilized subdurally positioned graphene electrodes for simultaneous recording and stimulation of the motor cortex in rhesus monkeys. Additionally, we implemented a wireless recordin

This study examined the long-term effects of low social status on adult prefrontal cortex (PFC), hippocampus (HIPPO) structure, functional connectivity and cognitive function using a translational rhesus monkey model.Twenty seven female rhesus monkeys (13 dominant -DOM-, 14 subordinate -SUB-) received structural- and resting-state functional MRI scans to examine the volume of and functional connectivity (FC) between HIPPO and PFC subregions important for executive function, working memory and reward monitoring (dorsolateral PFC(dlPFC) -Area 46-; orbitofrontal cortex(OFC) -Area 13-; medial PFC(

Understanding the neural underpinnings of social communication and emotional processing in non-human primates remains a significant challenge in neuroscience. In primates, studies using neuroimaging techniques such as fMRI, and electrophysiological recordings have identified several voice-sensitive cortical areas, i.e., the so-called voice patches. These voice patches are believed to be crucial for processing and distinguishing various vocalizations made by individuals of the same species (see for review Belin et al. 2018; and Bondin et al. 2021). In this study, we used fMRI (0.6 isotropic vox

Sequential decision-making in a dynamic environment requires foresight into future states often influenced by other agents. This study seeks to uncover the neural correlates underlying the computation of self and opponent action values in the brain. To achieve this, rhesus monkeys were trained in a competitive strategy board game, called “four-in-a-row,” in which they placed a series of stones on a 4-by-9 board, taking turns with a computer opponent. In this game, players win by placing a series of four stones horizontally, vertically, or diagonally, and the animal was rewarded only for winnin

Decision-making is a higher-order brain function that consists in choosing between behaviors/options. Basal ganglia (BG) dysfunction is known to be involved in decision-making deficits observed in patients suffering from BG-related disorders including neurological (e.g., Parkinson's disease) and psychiatric (e.g., obsessive compulsive disorders) disorders. However, the neural mechanisms and computations of decision-making in BG network are elusive and do not satisfactorily reflect the complex and known BG anatomy and physiology. Moreover, there are different types of value-related information