Neuroprotective and Neurorestorative Processes after Spinal Cord Injury: The Case of the Bulbospinal Respiratory Neurons

Figure 1

Diagram showing the spontaneous neural plasticity of the respiratory drive after cervical spinal cord injury. Green color represents active neural network. Red color represents silent or inactive neuronal network. (a, b) Unilateral injury leads to inactivation of ipsilateral premotoneurons from the brainstem or spinal cord (C1 interneurons). (c) In subchronic condition, the neurorestorative pathways include activation of CPP (contralateral premotoneurons in subchronic condition). (d) In chronic rerouting of unilateral premotoneurons through collateral connection to C1 interneurons. These last interneurons relay to phrenic motoneurons. BS: brainstem; C1–C3: cervical levels; EMG: electromyogram of hemidiaphragm SC: spinal cord; PMN: phrenic motoneuron; PN: phrenic nerve.

(a) Intact

(b) C2 unilateral injury

(c) Subchronic condition

(d) Chronic condition