Biology subjects

Safaie, M.

Publications and source records attributed to Safaie, M..

3 recordsLinked to original sources

bioRxiv2022

Preserved neural population dynamics across animals performing similar behaviour

Animals of the same species often exhibit similar behaviours that are advantageously adapted to their body and their environment. These behaviours are shaped by selection pressures over evolutionary timescales at the species level, yet each individual produces these behaviours using a different, uniquely constructed brain. It remains unclear how these common behavioural adaptations emerge from the idiosyncratic neural circuitry of a given individual. Here, we hypothesised that the adaptive behaviour of a species requires specific neural population latent dynamics. These latent dynamics should thus be preserved and identifiable across individuals within a species, regardless of the idiosyncratic aspects of each individuals brain. Using recordings of neural populations from monkey and mouse motor cortex, we show that individuals from the same species share surprisingly similar neural dynamics when they perform the same behaviour. The similarity in neural population dynamics extends beyond cortical regions to the dorsal striatum, an evolutionarily older structure, and also holds when animals con-sciously plan future movements without overt behaviour. These preserved dynamics are behaviourally-relevant, allowing decoding of intended and ongoing movements across individuals. We posit that these emergent neural population dynamics result from evolutionarily-imposed constraints on brain development, and reflect a fundamental property of the neural basis of behaviour.

neuroscience↗

bioRxiv2020

The dorsal striatum sets the sensitivity to effort

The dorsal striatum (dS) has been implicated in storing and retrieving procedural memories and controlling movement kinematics (e.g., speed). Since procedural memories are expressed through movements, the exact nature of the dS function has proven difficult to delineate. Here we challenged rats in complementary tasks designed to alleviate this performance confound. Surprisingly, dS lesions spared task-specific procedural memories but altered the kinematics of their expression in motor routines. Further behavioral analyses combined with simulations in the optimal control framework indicated that these alterations reflected an increased sensitivity to effort with preserved reward-seeking and ability to modulate movement speed. By setting the sensitivity to effort, the dS contributes to the optimization of the energy invested into voluntary movements. Such an elementary function of the dS might explain its implication in both procedural decisions and the control of movement speed.

neuroscience↗

bioRxiv2019

The Embodied Nature of Well-Timed Behavior

How animals adapt their movements to take advantage of behaviorally-relevant time intervals is not well understood, especially in the supra-second timescale. It has been proposed that motor timing depends on the emergence of self-sustained dynamics across ensembles of neurons. Alternatively, evidence from operant conditioning suggests that animals can develop motor routines to adapt their behavior to fixed temporal constraints. But it is unclear whether animals can accurately time their behavior without the help of motor routines. To address this issue, we used a task in which rats, freely moving on a motorized treadmill, could obtain a reward if they approached it after a fixed interval. Most animals took advantage of the treadmill length and its moving direction to develop, by trial-and-error, a unique motor routine whose execution resulted in the precise timing of their reward approaches. Noticeably, when proficient animals occasionally failed to follow this routine, the timing of their reward approaches was systematically poor. In a second step, we trained naive animals in modified versions of the task specifically designed to prevent the development of this motor strategy. Compared to rats trained in the first protocol, these animals never reached a comparable level of timing accuracy. We conclude that motor timing critically depends on the ability of animals to develop motor routines adapted to the structure of their environment. Our work also suggests that self-sustained neuronal activity alone may not be sufficient to support motor timing, at least in the supra-second timescale.

animal behavior and cognition↗