Idée - Computational neuroscience - # Rule-based modulation of sensorimotor processing across cortical areas

Flexible Rule-Dependent Sensorimotor Transformation Encoded in Cortical Population Dynamics

Q: How might the rule-dependent preparatory states in the motor cortex interact with other brain regions, such as the frontal and parietal areas, to enable flexible sensorimotor transformations

The rule-dependent preparatory states in the motor cortex likely interact with other brain regions, such as the frontal and parietal areas, through a network of interconnected pathways. The frontal cortex is known to play a crucial role in executive functions, including rule representation and cognitive control. It is involved in maintaining and updating rule representations, guiding sensorimotor transformations, and integrating contextual information for decision-making. The parietal cortex, on the other hand, is essential for processing sensory information, spatial awareness, and sensorimotor integration. The interaction between the motor cortex and these higher-order brain regions is likely bidirectional. The frontal cortex may provide top-down signals to the motor cortex to set the appropriate preparatory states based on the current rule. These signals could include abstract rule representations, task goals, and cognitive strategies. In return, the motor cortex may send feedback signals to the frontal cortex regarding the execution of motor plans, the outcome of sensorimotor transformations, and the need for adjustments in response to changing rules. The parietal cortex, with its role in sensory processing and spatial awareness, may contribute by providing real-time sensory feedback to the motor cortex to ensure accurate sensorimotor transformations. Overall, the interaction between the rule-dependent preparatory states in the motor cortex and other brain regions enables flexible sensorimotor transformations by integrating rule representations, sensory information, cognitive control, and motor planning.

Q: What are the potential mechanisms by which the motor cortex configures its preparatory states in a rule-dependent manner, and how might this process be disrupted in neurological or psychiatric disorders

The motor cortex configures its preparatory states in a rule-dependent manner through a combination of neural mechanisms involving synaptic plasticity, neural oscillations, and network dynamics. One potential mechanism is the modulation of synaptic strength and connectivity within the motor cortex based on the current rule. This could involve changes in the excitability of neurons, the strength of synaptic connections, and the balance between inhibitory and excitatory inputs. These synaptic changes may be driven by neuromodulatory signals from other brain regions, such as the frontal cortex, that encode rule information. Another mechanism could involve the synchronization of neural oscillations within the motor cortex to coordinate the activity of neuronal ensembles responsible for different motor plans. Oscillatory activity in specific frequency bands, such as beta and gamma rhythms, may play a role in organizing preparatory states for rule-dependent sensorimotor transformations. Disruption of these oscillatory patterns could lead to impaired rule-guided behavior. In neurological or psychiatric disorders, such as autism spectrum disorder or schizophrenia, disruptions in the mechanisms underlying rule-dependent preparatory states in the motor cortex may contribute to deficits in flexible behavior and cognitive control. For example, alterations in synaptic plasticity, aberrant neural oscillations, or dysfunctional connectivity between the motor cortex and other brain regions could lead to difficulties in adapting to changing rules, processing sensory information, and executing appropriate motor responses.

Q: Could the insights from this study on rule-based sensorimotor processing be extended to understand how the brain flexibly adapts to other types of contextual information, such as spatial or temporal cues, to guide behavior

The insights from this study on rule-based sensorimotor processing can be extended to understand how the brain flexibly adapts to other types of contextual information, such as spatial or temporal cues, to guide behavior. Just as the motor cortex configures its preparatory states based on task rules in the current study, other brain regions may similarly adjust their activity patterns in response to different contextual cues. For spatial cues, regions involved in spatial processing, such as the hippocampus and parietal cortex, may establish preparatory states that facilitate spatial navigation, memory encoding, and goal-directed movements. These preparatory states could involve the representation of spatial maps, landmarks, and directional information to guide behavior in spatially complex environments. Regarding temporal cues, areas involved in timing and temporal processing, such as the prefrontal cortex and basal ganglia, may set preparatory states that enable accurate timing of motor responses, synchronization of neural activity, and anticipation of upcoming events. These preparatory states could involve the encoding of temporal intervals, rhythmic patterns, and temporal expectations to optimize behavioral outcomes. By studying how different brain regions configure their preparatory states in response to various contextual cues, researchers can gain a comprehensive understanding of how the brain flexibly adapts to diverse environmental demands and orchestrates complex behaviors.

Concepts de base

Flexible selection of appropriate actions in response to sensory inputs is achieved through rule-dependent configuration of preparatory states in the motor cortex.

Résumé

The study investigated how task rules modulate the sensorimotor transformation in a cross-modal sensory selection task. Key findings:

Single-neuron and population activity in the somatosensory (S1, S2) and motor (MM, ALM) cortical areas reflected the current task rule, both before and in response to the tactile stimulus.
Neural subspaces containing the trial activity differed between the two rules across the cortical areas, and the pre-stimulus subspace overlap predicted the subsequent divergence of neural trajectories.
Pre-stimulus population states in the motor cortical areas (MM, ALM) shifted in a manner that tracked the rule switch, while the sensory cortical areas (S1, S2) showed limited rule-dependent changes.
Optogenetic disruption of pre-stimulus states within the motor cortical areas impaired rule-dependent tactile detection, but not simple tactile detection.

These results indicate that flexible selection of appropriate actions in response to sensory inputs is achieved through rule-dependent configuration of preparatory states in the motor cortex.

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biorxiv.org

Stats

"Approximately 15-35 percent of neurons showed significant difference between tHit and tCR responses in S1 (28.8%), S2 (17.9%), MM (32.9%) and ALM (23.4%)."
"The percentages of units showing significant discriminability (Bonferroni corrected 95% CI of AUC did not include 0.5) were higher in motor cortical regions (MM: 21.4%; ALM: 10.2%) than in sensory cortical regions (S1: 4.5%; S2: 2.5%)."
"Optogenetic inhibition of MM and ALM, but not S1 and S2, during the pre-stimulus period decreased tactile detection sensitivity in the cross-modal task."

Citations

"Flexible selection of appropriate actions in response to sensory inputs can occur via configuration of preparatory states in the motor cortex."
"Pre-stimulus population states in the motor cortical areas shifted in a manner that tracked the rule switch, while the sensory cortical areas showed limited rule-dependent changes."
"Optogenetic disruption of pre-stimulus states within the motor cortical areas impaired rule-dependent tactile detection, but not simple tactile detection."

Idées clés tirées de

Rule-based modulation of a sensorimotor transformation across cortical areas

by Chang,Y.-T.,... à www.biorxiv.org 08-22-2023

https://www.biorxiv.org/content/10.1101/2023.08.21.554194v2

Questions plus approfondies

How might the rule-dependent preparatory states in the motor cortex interact with other brain regions, such as the frontal and parietal areas, to enable flexible sensorimotor transformations

The rule-dependent preparatory states in the motor cortex likely interact with other brain regions, such as the frontal and parietal areas, through a network of interconnected pathways. The frontal cortex is known to play a crucial role in executive functions, including rule representation and cognitive control. It is involved in maintaining and updating rule representations, guiding sensorimotor transformations, and integrating contextual information for decision-making. The parietal cortex, on the other hand, is essential for processing sensory information, spatial awareness, and sensorimotor integration.
The interaction between the motor cortex and these higher-order brain regions is likely bidirectional. The frontal cortex may provide top-down signals to the motor cortex to set the appropriate preparatory states based on the current rule. These signals could include abstract rule representations, task goals, and cognitive strategies. In return, the motor cortex may send feedback signals to the frontal cortex regarding the execution of motor plans, the outcome of sensorimotor transformations, and the need for adjustments in response to changing rules. The parietal cortex, with its role in sensory processing and spatial awareness, may contribute by providing real-time sensory feedback to the motor cortex to ensure accurate sensorimotor transformations.
Overall, the interaction between the rule-dependent preparatory states in the motor cortex and other brain regions enables flexible sensorimotor transformations by integrating rule representations, sensory information, cognitive control, and motor planning.

What are the potential mechanisms by which the motor cortex configures its preparatory states in a rule-dependent manner, and how might this process be disrupted in neurological or psychiatric disorders

The motor cortex configures its preparatory states in a rule-dependent manner through a combination of neural mechanisms involving synaptic plasticity, neural oscillations, and network dynamics. One potential mechanism is the modulation of synaptic strength and connectivity within the motor cortex based on the current rule. This could involve changes in the excitability of neurons, the strength of synaptic connections, and the balance between inhibitory and excitatory inputs. These synaptic changes may be driven by neuromodulatory signals from other brain regions, such as the frontal cortex, that encode rule information.
Another mechanism could involve the synchronization of neural oscillations within the motor cortex to coordinate the activity of neuronal ensembles responsible for different motor plans. Oscillatory activity in specific frequency bands, such as beta and gamma rhythms, may play a role in organizing preparatory states for rule-dependent sensorimotor transformations. Disruption of these oscillatory patterns could lead to impaired rule-guided behavior.
In neurological or psychiatric disorders, such as autism spectrum disorder or schizophrenia, disruptions in the mechanisms underlying rule-dependent preparatory states in the motor cortex may contribute to deficits in flexible behavior and cognitive control. For example, alterations in synaptic plasticity, aberrant neural oscillations, or dysfunctional connectivity between the motor cortex and other brain regions could lead to difficulties in adapting to changing rules, processing sensory information, and executing appropriate motor responses.

Could the insights from this study on rule-based sensorimotor processing be extended to understand how the brain flexibly adapts to other types of contextual information, such as spatial or temporal cues, to guide behavior

The insights from this study on rule-based sensorimotor processing can be extended to understand how the brain flexibly adapts to other types of contextual information, such as spatial or temporal cues, to guide behavior. Just as the motor cortex configures its preparatory states based on task rules in the current study, other brain regions may similarly adjust their activity patterns in response to different contextual cues.
For spatial cues, regions involved in spatial processing, such as the hippocampus and parietal cortex, may establish preparatory states that facilitate spatial navigation, memory encoding, and goal-directed movements. These preparatory states could involve the representation of spatial maps, landmarks, and directional information to guide behavior in spatially complex environments.
Regarding temporal cues, areas involved in timing and temporal processing, such as the prefrontal cortex and basal ganglia, may set preparatory states that enable accurate timing of motor responses, synchronization of neural activity, and anticipation of upcoming events. These preparatory states could involve the encoding of temporal intervals, rhythmic patterns, and temporal expectations to optimize behavioral outcomes.
By studying how different brain regions configure their preparatory states in response to various contextual cues, researchers can gain a comprehensive understanding of how the brain flexibly adapts to diverse environmental demands and orchestrates complex behaviors.