Biology subjects

Desrochers, T. M.

Publications and source records attributed to Desrochers, T. M..

10 recordsLinked to original sources

bioRxiv2026

Linking cross-species hemodynamics with neuronal activity in prefrontal cortex during abstract sequence viewing

The ability to identify and predict abstract sequential patterns enables a wide range of complex cognition and behavior, but the mechanisms mediating it remain poorly understood. Lateral prefrontal cortex (LPFC) has been implicated in abstract sequence tracking in both humans and macaques, but it is unclear whether underlying processes are shared across species. Furthermore, most existing evidence relies on hemodynamic responses, which can have variable relationships with neuronal activity in a region. We leverage a combination of human fMRI, monkey fMRI, and monkey electrophysiology to bridge these gaps. We find that humans and non-human primates show functionally homologous hemodynamic activation in LPFC during abstract sequence viewing, and neuronal responses within fMRI-targeted regions in macaques contain information about sensory and abstract variables in parallel. However, neuronal activity does not directly mirror hemodynamic responses, and abstract sequence responses are found both near and far from fMRI peaks. In contrast, distinct dynamics of spiking activity are selectively present near fMRI peaks, suggesting that temporal coordination across neurons may influence hemodynamic activity in prefrontal cortex. Together, these experiments establish a link between human brain activity, macaque fMRI, and single neuron responses, providing a window into the neural processes that mediate abstract sequence detection.

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bioRxiv2026

Nonhuman primates exhibit error type-dependent post-error slowing across modalities

Mistakes make up our daily lives. Once a mistake has been committed, it is common to pause before you continue. This slowing is called post-error slowing (PES). Although several theories have been proposed to account for PES in humans, findings across cognitive tasks show variation in how PES occurs, and it is unclear how this phenomenon may translate across modalities to a key model organism of human cognition, macaque monkeys. To determine whether monkeys exhibit PES, we tested three rhesus macaque monkeys in components of cognitive sequential decision-making tasks that used either eye tracking or touch screens to report responses. Here we show that monkeys exhibit non-adaptive, error type-dependent PES across modalities. Task structure and context also modulated PES in the eye tracking task, and no modality improved task performance following PES. These results suggest that monkey PES is a combination of cognitive and non-cognitive related responses to error that are modulated by task structures such as error type and task context. Overall, the flexibility in monkey PES is comparable to that of humans, further supporting the importance of monkeys as a translational model in investigating the mechanisms of PES.

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bioRxiv2026

Obsessive-compulsive disorder and abstract sequence task contributions shift prefrontal cortical connectivity

Obsessive-compulsive disorder (OCD) is characterized, in part, by repetitive, sequential behaviors, such as cleaning rituals, yet underlying neural circuitry related to abstract sequencing in OCD remains poorly understood. Prior work has implicated a set of cortical regions activated during abstract sequences, which are defined by rules rather than specific stimulus features (Desrochers et al., 2022). These regions include the rostrolateral prefrontal cortex (RLPFC) that is necessary for performance on abstract sequence tasks (Desrochers et al., 2015), as well as the anterior cingulate cortex/dorsolateral prefrontal cortex (ACC/DLPFC), supplementary motor area (SMA), middle temporal gyrus (MTG), and temporo-occipital junction (TOJ) that are differentially activated in OCD compared to healthy participants during abstract sequencing (Doyle et al., 2026). It remains unclear, however, whether these regions form a coordinated circuit, and how their interactions may differ in OCD. In the present study, we examined task based functional and effective connectivity among these regions using a previously published dataset. We tested hypotheses that connectivity within this circuit would be altered in OCD relative to healthy controls (HCs), and that prefrontal regions (ACC/DLPFC and RLPFC) would direct information to downstream regions (SMA, MTG, and TOJ) during a sequential task. We found that connectivity within this circuit differed significantly between groups. HCs exhibited less negative connectivity from the ACC/DLPFC to the TOJ and stronger positive coupling between the MTG and TOJ, as well as stronger coordination between the RLPFC and DLPFC, suggesting coordinated prefrontal control. In contrast, individuals with OCD showed increased connectivity between the RLPFC and MTG, indicating a more direct influence of RLPFC on posterior regions. Effective connectivity analyses further indicated that, across participants, the ACC/DLPFC and MTG function as central hubs of information flow, with task-related inputs entering the circuit via the TOJ, propagating through the MTG to the RLPFC, and subsequently modulating ACC/DLPFC and downstream regions. These findings suggest a shared underlying circuit architecture in OCD and healthy participants despite differences in functional coupling, particularly involving prefrontal cortical regions. Overall, differences arise at the level of functional coordination within a preserved circuit for abstract sequential processing in OCD, adding to current neurobiological models of OCD and suggesting a novel circuit that supports abstract sequencing.

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bioRxiv2024

Ramping dissociates motor and cognitive sequences in the parietal and prefrontal cortices

Humans complete different types of sequences as a part of everyday life. These sequences can be divided into two important categories: those that are abstract, in which the steps unfold according to a rule at super-second to minute time scale, and those that are motor, defined solely by individual movements and their order which unfold at the sub-second to second timescale. For example, the sequence of making spaghetti consists of abstract tasks (preparing the sauce and cooking the noodles) and nested motor actions (stir pasta water). Previous work shows neural activity increases (ramps) in the rostrolateral prefrontal (RLPFC) during abstract sequence execution (Desrochers et al., 2015, 2019). During motor sequence production, activity occurs in regions of the prefrontal cortex (Yewbrey et al., 2023). However, it remains unknown if ramping is a signature of motor sequence production as well or solely an attribute of abstract sequence monitoring and execution. We tested the hypothesis that significant ramping activity occurs during motor sequence production in the RLPFC. Contrary to our hypothesis, we did not observe significant ramping activity in the RLPFC during motor sequence production, but we found significant ramping activity in bilateral inferior parietal cortex, in regions distinct from those observed during an abstract sequence task. Our results suggest different prefrontal-parietal circuitry may underlie abstract versus motor sequence execution.

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bioRxiv2024

Cognitive sequences in obsessive-compulsive disorder are supported by frontal cortex ramping activity and mediated by symptom severity

Completing sequences is a routine part of daily life. Many are abstract, defined by a rule governing the order rather than the identity of individual steps (e.g., getting dressed). In obsessive-compulsive disorder (OCD), excessive ritualistic behaviors suggest a disruption in abstract sequence completion. Executing abstract sequences requires at least two levels in a hierarchy of cognitive control: abstract sequential control (tracking steps) and task switching (shifting between tasks). While task switching has been studied in OCD, little is known in a sequential context. Understanding both hierarchical control types is key to uncovering how abstract sequences with nested task switches are processed in OCD. Previous studies showed that the rostrolateral prefrontal cortex (RLPFC) supports abstract sequence monitoring in healthy individuals with an increase in activity across each sequence, a dynamic known as "ramping". Ramping outside the RLPFC is potentially indicative of other sequence-related processes such as progress towards a goal and increasing working memory load. Therefore, we hypothesized that abstract sequential control deficits would correspond to altered ramping dynamics in RLPFC and other cortical regions. Second, we predicted task switching deficits in OCD, coupled with altered activity in cortical regions canonically implicated in task level control. We found partial support for both hypotheses. Abstract sequential control did not show behavioral differences in OCD but did show increased overall ramping in the anterior cingulate cortex (ACC) and superior frontal sulcus (SFS) and ramping differences in additional, novel cortical regions according to abstract sequence complexity. In contrast, behavioral differences were observed for task switching in OCD without neural differences between the groups. Together, these results suggest a group of areas support sequential control differentially in OCD than in healthy controls, despite behavioral similarity, and that this observation is likely not the result of neural deficits in task switching. These findings thus provide insight into OCD during complex behaviors more similar to daily life where sequence and task level control are intertwined and may inform future potential treatment.

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bioRxiv2024

Monkey lateral prefrontal cortex subregions differentiate between perceptual exposure to visual stimuli

Each day, humans must parse visual stimuli with varying amounts of perceptual experience, ranging from incredibly familiar to entirely new. Even when choosing a novel to buy at a bookstore, one sees covers they have repeatedly experienced intermixed with recently released titles. Visual exposure to stimuli has distinct neural correlates in the lateral prefrontal cortex (LPFC) of nonhuman primates. However, it is currently unknown if this function may be localized to specific subregions within LPFC. Specifically, we aimed to determine whether the posterior fundus of area 46 (p46f), an area that responds to deviations from learned sequences, also responds to less frequently presented stimuli outside of the sequential context. We compare responses in p46f to the adjacent subregion, posterior ventral area 46 (p46v), which we propose may be more likely to show exposure-dependent responses due to its proximity to novelty responsive regions. To test whether p46f or p46v represent perceptual exposure, we performed awake functional magnetic resonance imaging (fMRI) on three male monkeys as they observed visual stimuli that varied in their number of daily presentations. Here we show that p46v, but not p46f, shows preferential activation to stimuli with low perceptual exposure, further localizing exposure-dependent effects in monkey LPFC. These results align with previous research that has found novelty responses in ventral LPFC and are consistent with the proposal that p46f performs a sequence-specific function. Further, they expand on our knowledge of the specific role of LPFC subregions and localize perceptual exposure processing within this broader brain region.

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bioRxiv2024

Monkey dorsolateral prefrontal cortex shows anatomically and functionally specific responses to sequential but not temporal or image changes

Sequential information permeates daily activities, such as when watching for the correct series of buildings to determine when to get off the bus or train. These sequences include periodicity (the spacing of the buildings), the identity of the stimuli (the kind of house), and higher-order more abstract rules that may not depend on the exact stimulus (e.g. house, house, house, business). Previously, we found that the posterior fundus of area 46 in the monkey lateral prefrontal cortex (LPFC) responds to rule changes in such abstract visual sequences. However, it is unknown if this region responds to other components of the sequence, i.e., image periodicity and identity, in isolation. Further, it is unknown if this region dissociates from other, more ventral LPFC subregions that have been associated with sequences and their components. To address these questions, we used awake functional magnetic resonance imaging in three male macaque monkeys during two no-report visual tasks. One task contained abstract visual sequences, and the other contained no visual sequences but maintained the same image periodicity and identities. We found the fundus of area 46 responded only to abstract sequence rule violations. In contrast, the ventral bank of area 46 responded to changes in image periodicity and identity, but not changes in the abstract sequence. These results suggest a functional specialization within anatomical substructures of LPFC to signal different kinds of stimulus regularities. This specialization may provide key scaffolding to identify abstract patterns and construct complex models of the world for daily living. Significance StatementDaily tasks, such as a bus commute, require tracking or monitoring your place (same, same, same, different building) until your stop. Sequence components such as rule, periodicity (timing), and item identity are involved in this process. While prior work located responses to sequence rule changes to area 46 of monkey lateral prefrontal cortex (LPFC) using awake monkey fMRI, less was known about other components. We found that LPFC subregions differentiated between sequence components. Area 46 posterior fundus responded to abstract visual sequence rule changes, but not to changes in image periodicity or identity. The converse was true for the more ventral, adjacent shoulder region. These results suggest that interactions between adjacent LPFC subregions provide key scaffolding for complex daily behaviors.

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bioRxiv2022

Monkey dorsolateral prefrontal cortex represents abstract visual sequences during a no-report task

Monitoring sequential information is an essential component of our daily lives. Many of these sequences are abstract, in that they do not depend on the individual stimuli, but do depend on an ordered set of rules (e.g., chop then stir when cooking). Despite the ubiquity and utility of abstract sequential monitoring, little is known about its neural mechanisms. Human rostrolateral prefrontal cortex (RLPFC) exhibits specific increases in neural activity (i.e., "ramping") during abstract sequences. Monkey dorsolateral prefrontal cortex (DLPFC) has been shown to represent sequential information in motor (not abstract) sequence tasks, and contains a sub-region, area 46, with homologous functional connectivity to human RLPFC. To test the prediction that area 46 may represent abstract sequence information, and do so with parallel dynamics to those found in humans, we conducted functional magnetic resonance imaging (fMRI) in monkeys. When monkeys performed no-report abstract sequence viewing, we found that left and right area 46 responded to abstract sequential changes. Interestingly, responses to rule and number changes overlapped in right area 46 and left area 46 exhibited responses to abstract sequence rules with changes in ramping activation, similar to that observed in humans. Together, these results indicate that monkey DLPFC monitors abstract visual sequential information, potentially with a preference for different dynamics in the two hemispheres. More generally, these results show that abstract sequences are represented in functionally homologous regions across monkeys and humans. Significance StatementDaily, we complete sequences that are "abstract" because they depend on an ordered set of rules (e.g., chop then stir when cooking) rather than the identity of individual items. Little is known about how the brain tracks, or monitors, this abstract sequential information. Based on previous human work showing abstract sequence related dynamics in an analogous area, we tested if monkey dorsolateral prefrontal cortex (DLPFC), specifically area 46, represents abstract sequential information using awake monkey fMRI. We found that area 46 responded to abstract sequence changes, with a preference for more general responses on the right and dynamics similar to humans on the left. These results suggest that abstract sequences are represented in functionally homologous regions across monkeys and humans.

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bioRxiv2021

A Role for Visual Areas in Physics Simulations

To engage with the world, we must regularly make predictions about the outcomes of physical scenes. How do we make these predictions? Recent evidence points to simulation - the idea that we can introspectively manipulate rich, mental models of the world - as one possible explanation for how such predictions are accomplished. While theories based on simulation are supported by computational models, neuroscientific evidence for simulation is lacking and many important questions remain. For instance, do simulations simply entail a series of abstract computations? Or are they supported by sensory representations of the objects that comprise the scene being simulated? We posit the latter and suggest that the process of simulating a sequence of physical interactions is likely to evoke an imagery-like envisioning of those interactions. Using functional magnetic resonance imaging, we demonstrate that when participants predict how a ball will fall through an obstacle-filled display, motion-sensitive brain regions are activated. We further demonstrate that this activity, which occurs even though no motion is being sensed, resembles activity patterns that arise while participants perceive the balls motion. This finding suggests that the process of simulating the balls movement is accompanied by a sensory representation of this movement. These data thus demonstrate that mental simulations recreate sensory depictions of how a physical scene is likely to unfold.

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bioRxiv2020

Abstract sequential task control is facilitated by practice and embedded motor sequences

Everyday task sequences, such as cooking, contain overarching goals (completing the meal), sub-goals (prepare vegetables), and motor actions (chopping). Such tasks generally are considered hierarchical because superordinate levels (e.g., goals) affect performance at subordinate levels (e.g., sub-goals and motor actions). However, there is debate as to whether this hierarchy is "strict" with unidirectional, top-down influences, and it is unknown if and how practice affects performance at the superordinate levels. To investigate these questions, we manipulated practice with sequences at the goal and motor action levels using an abstract, or non-motor, task sequence paradigm (Desrochers et al., 2015; Schneider & Logan, 2006). In three experiments, participants performed memorized abstract task sequences composed of simple tasks (e.g., color/shape judgements), where some contained embedded motor response sequences. We found that practice facilitated performance and reduced control costs for abstract task sequences and subordinate tasks. The interrelation was different between the hierarchical levels, demonstrating a strict relationship between abstract task sequence goals and sub-goals and a non-strict relationship between sub-goal and motor response levels. Under some conditions, the motor response level influenced the abstract task sequence level in a non-strict manner. Further, manipulating the presence or absence of a motor sequence after learning indicated that these effects were not the result of an integrated representation produced by practice. These experiments provide evidence for a mixed hierarchical model of task sequences and insight into the distinct roles of practice and motor processing in efficiently executing task sequences in daily life.

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