Intraspinal microstimulation A novel technique for the functional recovery of spinal cord injury

Nonspecific neuronal activity elicited by intraspinal microstimulation in the intermediate and ventral gray matter of thoracic spinal segments caudal to a complete spinal cord transection significantly increased the rat hindlimb Basso, Beattie, Bresnahan locomotor score by activating the central pattem generator located in the lumbar spinal cord. However, the best region for intraspinal microstimulation is unclear. Using an incomplete spinal cord injury model at T8, we compared the use of intraspinal microstimulation to activate the spinal cord in rats with a spontaneous recovery group. The intraspinal microstimulation group recovered sooner and showed three kinds of movement： the left hindlimb, the left hindlimb toes, and the paraspinal muscles and tails. These had different microstimulation thresholds. There was mild hyperplasia of the astrocytes surrounding the tips of the microelectrodes and slight inflammatory reactions nearby. These results indicate that implantation of microelectrodes was relatively safe and induced minimal damage to the lumbar-sacral spinal cord. Intraspinal microstimulation in the lumbar sacral spinal cord may improve leg movements after spinal cord injury. Non-specific intraspinal microstimulation may be a novel technique for the recovery of spinal cord injuries.

Modulating Motor Behaviors by Electrical Stimulation of Specific Nuclei in Pigeons

Pigeons （Columba livia） have excellent flying and orienting abilities and are ideal study subjects for biologists who re- search the underlying neurological mechanisms that modulate flying and allow birds to find their way home. These mechanisms also attract the engineers who want to apply pigeon locomotion to the design of flying robots. Here, we identified the mo- tor-related brain nuclei and revealed their relationship in spatial distribution in pigeons under light anesthesia and freely moving conditions respectively. Flapping and lateral body movements were successfully elicited when electrical microstimulation was applied to the diencephalon, medial part of the midbrain, and medulla oblongata of lightly anesthetized pigeons （N = 28） whose heads were fixed. The current thresholds for stimulating different nuclei and behavior ranged from 10 pA to 20 ~tA. During freely moving tests （N = 24）, taking off and turning were induced by a wireless stimulator through microelectrodes implanted in specific nuclei or brain regions. The results showed that electrical stimulation of these nuclei elicited the desired motor behavior. In addition, regulatory mechanisms were identified in the motor-related regions and nuclei of pigeons. Overlapping in the behavior elicited by stimulation of different regions indicates that complicated neural networks regulate motor behavior. Therefore, more studies need to be conducted involving simultaneous stimulation at multiple points within the nuclei involved in the networks.