Cutaneous Inputs to Dorsal Column Nuclei in Adult Macaque Monkeys Subjected to Unilateral Lesion of the Primary Motor Cortex or of the Cervical Spinal Cord and Treatments Promoting Axonal Growth.

The highly interconnected somatosensory and motor systems are subjected to connectivity changes at close or remote locations following a central nervous system injury. What is the impact of unilateral injury of the primary motor cortex (hand area; MCI) or of the cervical cord (hemisection at C7-C8 level; SCI) on the primary somatosensory (cutaneous) inputs to the dorsal column nuclei (DCN) in adult macaque monkeys? The effects of treatments promoting axonal growth were assessed. In the SCI group (n = 4), 1 monkey received a control antibody and 3 monkeys a combination treatment of anti-Nogo-A antibody and brain-derived neurotrophic factor (BDNF).

Assessment of the effect of continuous theta burst stimulation of the motor cortex on manual dexterity in non-human primates in a direct comparison with invasive intracortical pharmacological inactivation.

Non-invasive reversible perturbation techniques of brain output such as continuous theta burst stimulation (cTBS), commonly used to modulate cortical excitability in humans, allow investigation of possible roles in functional recovery played by distinct intact cortical areas following stroke. To evaluate the potential of cTBS, the behavioural effects of this non-invasive transient perturbation of the hand representation of the primary motor cortex (M1) in non-human primates (two adult macaques) were compared with an invasive focal transient inactivation based on intracortical microinfusion of GABA-A agonist muscimol. The effects on the contralateral arm produced by cTBS or muscimol were directly compared based on a manual dexterity task performed by the monkeys, the "reach and grasp" drawer task, allowing quantitative assessment of the grip force produced between the thumb and index finger and exerted on the drawer's knob.

Role of primary motor cortex in the control of manual dexterity assessed via sequential bilateral lesion in the adult macaque monkey: A case study.

From a case study, we describe the impact of unilateral lesion of the hand area in the primary motor cortex (M1) on manual dexterity and the role of the intact contralesional M1 in long-term functional recovery. An adult macaque monkey performed two manual dexterity tasks: (i) "modified Brinkman board" task, assessed simple precision grip versus complex precision grip, the latter involved a hand postural adjustment; (ii) "modified Klüver board" task, assessed movements ranging from power grip to precision grip, pre-shaping and grasping. Two consecutive unilateral M1 lesions targeted the hand area of each hemisphere, the second lesion was performed after stable, though incomplete, functional recovery from the primary lesion.

Distinction between hand dominance and hand preference in primates: a behavioral investigation of manual dexterity in nonhuman primates (macaques) and human subjects.

Background The present study aimed to determine and confront hand preference (hand chosen in priority to perform a manual dexterity task) and hand dominance (hand with best motor performance) in eight macaques (Macaca fascicularis) and in 20 human subjects (10 left-handers and 10 right-handers). Methods Four manual dexterity tests have been executed by the monkeys, over several weeks during learning and stable performance phases (in controlled body position): the modified Brinkman board, the reach and grasp drawer, the tube and the bimanual board tasks. Three behavioral tests, adapted versions from the monkeys tasks (modified Brinkman board, tube and bimanual board tasks), as well as a handedness questionnaire, have been conducted in human subjects.

Long-term motor cortical map changes following unilateral lesion of the hand representation in the motor cortex in macaque monkeys showing functional recovery of hand functions.

Purpose: How are motor maps modified within and in the immediate vicinity of a damaged zone in the motor cortex of non-human primates?

Methods: In eight adult macaque monkeys subjected to a restricted chemical lesion of the hand area in the primary motor cortex (M1), motor maps were established using intracortical micro-stimulation (ICMS) techniques. The monkeys were subdivided into five animals without treatment, whereas three monkeys received an anti-Nogo-A antibody treatment.

Results: Following permanent M1 injury, the lesion territory became largely non micro-excitable several months post-lesion, in spite of some recovery of hand function.

Behavioral assessment of manual dexterity in non-human primates.

The corticospinal (CS) tract is the anatomical support of the exquisite motor ability to skillfully manipulate small objects, a prerogative mainly of primates(1). In case of lesion affecting the CS projection system at its origin (lesion of motor cortical areas) or along its trajectory (cervical cord lesion), there is a dramatic loss of manual dexterity (hand paralysis), as seen in some tetraplegic or hemiplegic patients. Although there is some spontaneous functional recovery after such lesion, it remains very limited in the adult.