**4. Rehabilitation strategies based on the functional characteristics of the brain and advances in clinical practice guidelines**

Research by Geyer et al. [27] showed that the human primary motor cortex consists of two different regions: the anterior portion (IVa area) and the posterior portion (IVp area). These two regions differ in cell structure and receptor density. The IVa area is located in the anterior (rostral) portion of the primary motor cortex. This area is phylogenetically ancient and is thus referred to as the old primary motor cortex (Old M1). Outputs from the Old M1 control physical movement via the corticospinal tract and spinal interneurons. Meanwhile, the IVp area is found in the posterior (caudal) portion of the primary motor cortex and, being a newer section of the motor cortex compared to the IVa, is known as the New M1. New M1 includes cortical motoneurons, which synapse directly with spinal motoneurons. These synaptic connections are not mediated by spinal interneurons and are involved in the execution of extremely masterful and complex movements [28].

In light of the neural network functional disparity between the IVa and IVp areas of the primary motor cortex, Sharma et al. [29] proposed the somatosensory feedback for the paretic limb as one factor influencing the recovery of motor function after stroke (**Figure 4A**). The authors suggested that increased neural activity in the IVp area due to somatosensory input is involved in the recovery of motor function. Loubinoux et al. [30] investigated brain areas involved in motor function recovery for stroke patients using fMRI. They found that stroke patients with high neural activity in the IVp area had favorable motor function recovery in the hand and that neural activity in the IVp area predicted motor performance 1 year later. This suggests that early poststroke stimulation of neural activity in the IVp area of the injured hemisphere is critical for rehabilitation. As described above, the IVa and IVp areas are structurally disparate, but they are also functionally different with respect to afferent somatosensory information processing. Strick et al. [31] investigated differences in neural activity in the rostral (IVa) and caudal (IVp) areas of the primary motor cortex in monkeys using inputs from different sensory modalities. Their study found that the rostral primary motor cortex has plentiful cells that respond to the characteristic sensory input of muscles and joints, while the caudal area has an abundance of cells responding to cutaneous sensation input. Thus, it was suggested that providing cutaneous sensation to the paretic limb was important for increasing excitation in the IVp area. It was further found that neural activity in this IVp area was influenced by actively drawing attention. Binkofski et al. [32] examined the effect that directing attention to behavior had on neural activity in the IVa and IVp areas of the human primary motor cortex using fMRI. The authors found that the neural activity in the IVp area was affected by drawing attention to behavior, but this effect was not present in the IVa area. This suggested that apart from providing simple sensory stimulation, directing participants' active attention would also be beneficial for increasing neural activity in the IVp area. To summarize, for poststroke motor function recovery, it is considered important to increase the neural activity of the IVp area by providing somatosensory input to the paretic limb while capturing the patient's active attention.

**307**

**Figure 4.**

*Rehabilitation Strategies and Key Related Mechanisms Involved in Stroke Recovery*

Sharma et al. [29] proposed, as a second factor involved in poststroke recovery of motor function, activities preceding movement (**Figure 4B**). We know that the IVp area is excited in the same way by both the abovementioned somatosensory input and mental representations, such as motor imagery and preceding movement. Using fMRI and healthy adults, Sharma et al. [33] conducted a study of neural activity in the primary motor cortex (IVa and IVp areas) while the subjects imagined movement. The results demonstrated that the relative involvement of imagining movement was larger in the IVp area than that in the IVa area. Sharma et al. [34] then explored the relationship between neural activity in the primary motor cortex (IVa and IVp areas) in stroke patients, while imagining movement and motor performance using fMRI. The authors found that, while imagining movement of the paretic hand, the neural activity in the injured side of the IVp area of stroke patients was positively correlated with motor performance. These studies suggest that the neural activity of the IVp area, when imagining movement, can be used as a tool to predict motor function in stroke patients and, further, that intervention with

*Three factors influencing motor function recovery after a stroke and the corresponding neural networks [29]. The injured hemisphere is shown in gray and the non-injured hemisphere in white. (A) Somatosensory feedback: This network can be accessed through somatosensory input such as peripheral nerve stimulation. (B) Processes preceding movement such as a movement plan: This network can be accessed through motor imagery or action observation. (C) Discharge via the corticospinal tract to produce movement: This network is involved* 

*in physical movement but predominantly through the combination of the other two (A and B).*

tasks involving motor imagery may increase excitation in the IVp area.

*DOI: http://dx.doi.org/10.5772/intechopen.91025*

*Rehabilitation Strategies and Key Related Mechanisms Involved in Stroke Recovery DOI: http://dx.doi.org/10.5772/intechopen.91025*

#### **Figure 4.**

*New Insight into Cerebrovascular Diseases - An Updated Comprehensive Review*

inhibition between the left and right cerebrum.

complex movements [28].

package) [23, 24], as well as research examining the effects of motor therapy, which combines CI therapy with the abovementioned rTMS and tDCS [25, 26]. In this way, it is essential that motor therapy in the rehabilitation of stroke patients be developed with sufficient consideration to the imbalance in interhemispheric

**4. Rehabilitation strategies based on the functional characteristics** 

Research by Geyer et al. [27] showed that the human primary motor cortex consists of two different regions: the anterior portion (IVa area) and the posterior portion (IVp area). These two regions differ in cell structure and receptor density. The IVa area is located in the anterior (rostral) portion of the primary motor cortex. This area is phylogenetically ancient and is thus referred to as the old primary motor cortex (Old M1). Outputs from the Old M1 control physical movement via the corticospinal tract and spinal interneurons. Meanwhile, the IVp area is found in the posterior (caudal) portion of the primary motor cortex and, being a newer section of the motor cortex compared to the IVa, is known as the New M1. New M1 includes cortical motoneurons, which synapse directly with spinal motoneurons. These synaptic connections are not mediated by spinal interneurons and are involved in the execution of extremely masterful and

In light of the neural network functional disparity between the IVa and IVp areas of the primary motor cortex, Sharma et al. [29] proposed the somatosensory feedback for the paretic limb as one factor influencing the recovery of motor function after stroke (**Figure 4A**). The authors suggested that increased neural activity in the IVp area due to somatosensory input is involved in the recovery of motor function. Loubinoux et al. [30] investigated brain areas involved in motor function recovery for stroke patients using fMRI. They found that stroke patients with high neural activity in the IVp area had favorable motor function recovery in the hand and that neural activity in the IVp area predicted motor performance 1 year later. This suggests that early poststroke stimulation of neural activity in the IVp area of the injured hemisphere is critical for rehabilitation. As described above, the IVa and IVp areas are structurally disparate, but they are also functionally different with respect to afferent somatosensory information processing. Strick et al. [31] investigated differences in neural activity in the rostral (IVa) and caudal (IVp) areas of the primary motor cortex in monkeys using inputs from different sensory modalities. Their study found that the rostral primary motor cortex has plentiful cells that respond to the characteristic sensory input of muscles and joints, while the caudal area has an abundance of cells responding to cutaneous sensation input. Thus, it was suggested that providing cutaneous sensation to the paretic limb was important for increasing excitation in the IVp area. It was further found that neural activity in this IVp area was influenced by actively drawing attention. Binkofski et al. [32] examined the effect that directing attention to behavior had on neural activity in the IVa and IVp areas of the human primary motor cortex using fMRI. The authors found that the neural activity in the IVp area was affected by drawing attention to behavior, but this effect was not present in the IVa area. This suggested that apart from providing simple sensory stimulation, directing participants' active attention would also be beneficial for increasing neural activity in the IVp area. To summarize, for poststroke motor function recovery, it is considered important to increase the neural activity of the IVp area by providing somatosensory input to the paretic

**of the brain and advances in clinical practice guidelines**

**306**

limb while capturing the patient's active attention.

*Three factors influencing motor function recovery after a stroke and the corresponding neural networks [29]. The injured hemisphere is shown in gray and the non-injured hemisphere in white. (A) Somatosensory feedback: This network can be accessed through somatosensory input such as peripheral nerve stimulation. (B) Processes preceding movement such as a movement plan: This network can be accessed through motor imagery or action observation. (C) Discharge via the corticospinal tract to produce movement: This network is involved in physical movement but predominantly through the combination of the other two (A and B).*

Sharma et al. [29] proposed, as a second factor involved in poststroke recovery of motor function, activities preceding movement (**Figure 4B**). We know that the IVp area is excited in the same way by both the abovementioned somatosensory input and mental representations, such as motor imagery and preceding movement. Using fMRI and healthy adults, Sharma et al. [33] conducted a study of neural activity in the primary motor cortex (IVa and IVp areas) while the subjects imagined movement. The results demonstrated that the relative involvement of imagining movement was larger in the IVp area than that in the IVa area. Sharma et al. [34] then explored the relationship between neural activity in the primary motor cortex (IVa and IVp areas) in stroke patients, while imagining movement and motor performance using fMRI. The authors found that, while imagining movement of the paretic hand, the neural activity in the injured side of the IVp area of stroke patients was positively correlated with motor performance. These studies suggest that the neural activity of the IVp area, when imagining movement, can be used as a tool to predict motor function in stroke patients and, further, that intervention with tasks involving motor imagery may increase excitation in the IVp area.

A third factor influencing recovery of motor function after stroke suggested by Sharma et al. [29] is discharge via the corticospinal tract to produce movement (**Figure 4C**). This network is involved in all physical movement but predominantly through the combination of the other two. That is, this neural network for producing movement is predominantly utilized via the mutual involvement of the neural network based on somatosensory feedback and the neural network preceding movement. As a specific example, Nilsen et al. [35] and López et al. [36] conducted a systematic review and found that combining mental practice and the use of motor imagery with physical movement improved intervention effects. Further, a Cochrane Review [37] also reported that mental practice interventions combined with motor therapy, including physical movement, were more effective than mental practice alone. We also reported that neurofeedback-based motor imagery training combined with physical movement contributed to improving upper extremity function in stroke patients [38]. These findings indicate that somatosensory feedback accompanying physical movement promotes the effects of motor imagery interventions. In other words, the neural network preceding movement and that for somatosensory feedback may work together to enhance motor performance.

To summarize, the factors influencing motor function recovery accompanying the reorganization of the IVp area after a stroke are (1) somatosensory feedback to the paretic side; (2) movement-preceding activities, which utilize motor imagery and action observation; and (3) discharge via the corticospinal tract to produce movement. As (3) is ultimately effective through the combination of the neural networks involved in (1) and (2), information processing combined with somatosensory input to the paretic limb should take priority in motor therapy for hemiparetic stroke patients exhibiting motor paresis. Next, treatment should precede mental practice interventions utilizing motor imagery induction, based on estimations from that information processing and from motor practice producing movement through an exercise program based on those movement-preceding activities. This step-by-step intervention strategy is considered vital.

Nevertheless, according to the Guidelines for the Management of Stroke [39], the following therapies are recommended for rehabilitation for upper limb dysfunction—for patients with mild paralysis, a therapy that suppresses the non-paralyzed upper limb and forces the use of the paralyzed upper limb in life is highly recommended (grade A). For moderate paralytic muscles (such as wrist and finger extensors), electrical stimulation is recommended (grade B). For patients with mild to moderate paralysis, training should be performed with repetition of certain movements (reach movement of the upper limb on the paralyzed side, goal-oriented movement, repetitive movement of both upper limbs, mirror therapy, repetitive facilitation exercise, etc.) is recommended (grade B). rTMS and tDCS may be considered, but care must be taken in patient selection and safety (grade C1).

Moreover, the following therapies are recommended for rehabilitation for gait disorders—increasing the amount of limb training associated with walking or of walking itself is strongly recommended to improve walking ability (grade A). For stroke hemiplegic patients with equinovarus feet, it is recommended to use short leg braces to improve walking (grade B). Botulinum therapy and intramuscular nerve block to the tibial nerve or the lower leg muscle using 5% phenol is recommended when the spastic equinovarus foot hinders walking and ADL (grade B). Tendon transfer may be considered for patients presenting with spastic equinus and abnormal gait (grade C1). Biofeedback using electromyogram and joint angle is also recommended to improve walking (grade B). Functional electrical stimulation is recommended for chronic stroke patients with drooping foot, but the duration of treatment effect is short (grade B). Treadmill training is recommended because it improves walking speed and endurance in ambulatory stroke patients (grade B).

**309**

*Rehabilitation Strategies and Key Related Mechanisms Involved in Stroke Recovery*

Walking training using a walking assist robot is recommended for those who cannot

Furthermore, the following therapies are recommended for rehabilitation in cases of movement disorders and ADL. For stroke sequelae, active rehabilitation from the early stage is strongly recommended to promote the recovery of dysfunction and disability (grade A). It is strongly recommended to increase the amount and frequency of training early after onset to promote more effective recovery of disability in patients (grade A). For lower limb function and ADL, repeated task

Based on the above guidelines, it is necessary to consider three points: (1) dose dependency, (2) task dependency, and (3) neuroplasticity, in order to promote

In clinical practice, it is important to perform optimal rehabilitation for stroke patients while keeping the functional characteristics of the brain and the existing

In this chapter, we outlined the neural mechanisms underlying motor function recovery after stroke-related brain injury. We have also outlined the corresponding rehabilitation strategies based on the functional characteristics of the brain and advances in clinical practice guidelines. We discussed how, considering the functional characteristics of the primary motor area, it is important during the early stages after stroke to increase the somatosensory input to the paralyzed side and combine mental practices using motor imagery. The existing guidelines highlighted the importance of dose dependency, task dependency, and neuroplasticity, in promoting effective functional recovery in stroke rehabilitation. Understanding the rehabilitation strategies and key related mechanisms involved in stroke recovery is indispensable for the development of highly effective poststroke rehabilitation.

Previous studies have shown that the recovery of motor function after stroke is acutely related to the functional replacement of damaged neuronal circuits and the interhemispheric imbalance model. Therefore, it is important to promote neuroplasticity related to motor function recovery in rehabilitation. In addition to the use of evidence-based clinical practice guidelines, rehabilitation strategies that take into account the functional characteristics of the brain may maximize the recovery of motor function in stroke patients. In the future, it is expected that improved intervention strategies will be widely applied in the clinical setting by accumulating

knowledge about the pathology of relevant cases and brain areas.

The authors declare no conflict of interest.

*DOI: http://dx.doi.org/10.5772/intechopen.91025*

walk within 3 months of onset (grade B).

training is recommended (grade B).

guidelines in mind.

**5. Final remarks**

**6. Future directions**

**Conflict of interest**

effective functional recovery in stroke rehabilitation.

#### *Rehabilitation Strategies and Key Related Mechanisms Involved in Stroke Recovery DOI: http://dx.doi.org/10.5772/intechopen.91025*

Walking training using a walking assist robot is recommended for those who cannot walk within 3 months of onset (grade B).

Furthermore, the following therapies are recommended for rehabilitation in cases of movement disorders and ADL. For stroke sequelae, active rehabilitation from the early stage is strongly recommended to promote the recovery of dysfunction and disability (grade A). It is strongly recommended to increase the amount and frequency of training early after onset to promote more effective recovery of disability in patients (grade A). For lower limb function and ADL, repeated task training is recommended (grade B).

Based on the above guidelines, it is necessary to consider three points: (1) dose dependency, (2) task dependency, and (3) neuroplasticity, in order to promote effective functional recovery in stroke rehabilitation.

In clinical practice, it is important to perform optimal rehabilitation for stroke patients while keeping the functional characteristics of the brain and the existing guidelines in mind.
