M. Jeannerod explores the concept of motor imagery in the context of motor actions, proposing that motor images share the same properties as motor representations, including functional relationships and causal roles in generating movement. The timing of simulated movements aligns with actual movements, suggesting similar neural mechanisms are activated during motor imagery. Neural mechanisms, such as increased tendinous reflexes and vegetative changes, are activated during motor imagery. Cortical activation patterns during motor imagery resemble those during actual movement execution, supporting the idea that mental training can have similar effects. A hierarchical model of action organization is proposed, where motor representations are stored and activated based on the completeness of the action. If the action is not executed, the system remains activated, allowing for rehearsal of the representation. This mechanism underlies conscious access to motor imagery and mental training. Motor imagery is distinguished from other types of imagery by the strong connection between verbal and non-verbal systems. Visual images are easily described verbally, while motor images are not. However, motor representations are cognitively accessible through indirect methods. Studies show that mental simulation of actions can be measured through reaction times, which follow Fitts' law, indicating similar amplitude-accuracy relations in both real and imagined movements. Motor imagery activates motor output, as evidenced by increased spinal reflex excitability during mental simulation. Autonomic responses, such as changes in heart rate and respiration, are also activated during mental simulation, suggesting a preparation for action. Motor imagery activates specific cortical areas, including the supplementary motor area (SMA), prefrontal cortex, and cerebellum, similar to actual movement. Functional MRI studies confirm that motor imagery activates the SMA and parietal areas, with activation levels varying based on the complexity of the task. The effects of mental training on motor performance are well-documented, showing improvements in motor skills and performance. Mental training can enhance motor performance through central changes, such as increased motor cortex excitability and improved synaptic efficacy. These changes suggest that mental practice can lead to real-world improvements in motor skills. The model of self-generated actions proposes that motor representations are internal models of the action's goal, organized hierarchically. These representations are activated and controlled through a series of levels, with feedback mechanisms ensuring accurate execution. The model also suggests that motor imagery and execution have different time constants, with imagery taking longer to become conscious. This distinction is important for understanding the role of motor imagery in motor learning and the neural mechanisms underlying mental practice. The model also highlights the role of the basal ganglia and other structures in motor control and learning, emphasizing the importance of neural traffic and activation in motor imagery and mental simulation.M. Jeannerod explores the concept of motor imagery in the context of motor actions, proposing that motor images share the same properties as motor representations, including functional relationships and causal roles in generating movement. The timing of simulated movements aligns with actual movements, suggesting similar neural mechanisms are activated during motor imagery. Neural mechanisms, such as increased tendinous reflexes and vegetative changes, are activated during motor imagery. Cortical activation patterns during motor imagery resemble those during actual movement execution, supporting the idea that mental training can have similar effects. A hierarchical model of action organization is proposed, where motor representations are stored and activated based on the completeness of the action. If the action is not executed, the system remains activated, allowing for rehearsal of the representation. This mechanism underlies conscious access to motor imagery and mental training. Motor imagery is distinguished from other types of imagery by the strong connection between verbal and non-verbal systems. Visual images are easily described verbally, while motor images are not. However, motor representations are cognitively accessible through indirect methods. Studies show that mental simulation of actions can be measured through reaction times, which follow Fitts' law, indicating similar amplitude-accuracy relations in both real and imagined movements. Motor imagery activates motor output, as evidenced by increased spinal reflex excitability during mental simulation. Autonomic responses, such as changes in heart rate and respiration, are also activated during mental simulation, suggesting a preparation for action. Motor imagery activates specific cortical areas, including the supplementary motor area (SMA), prefrontal cortex, and cerebellum, similar to actual movement. Functional MRI studies confirm that motor imagery activates the SMA and parietal areas, with activation levels varying based on the complexity of the task. The effects of mental training on motor performance are well-documented, showing improvements in motor skills and performance. Mental training can enhance motor performance through central changes, such as increased motor cortex excitability and improved synaptic efficacy. These changes suggest that mental practice can lead to real-world improvements in motor skills. The model of self-generated actions proposes that motor representations are internal models of the action's goal, organized hierarchically. These representations are activated and controlled through a series of levels, with feedback mechanisms ensuring accurate execution. The model also suggests that motor imagery and execution have different time constants, with imagery taking longer to become conscious. This distinction is important for understanding the role of motor imagery in motor learning and the neural mechanisms underlying mental practice. The model also highlights the role of the basal ganglia and other structures in motor control and learning, emphasizing the importance of neural traffic and activation in motor imagery and mental simulation.