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

Abstract

Abstract-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 Klü ver 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. Following each lesion, the manual dexterity of the contralesional hand was affected in a comparable manner, effects being progressively more deleterious from power grip to simple and then complex precision grips. Both tasks yielded consistent data, namely that the secondary M1 lesion did not have a significant impact on the recovered performance from the primary M1 lesion, which took place 5 months earlier. In conclusion, the intact contralesional M1 did not play a major role in the long-term functional recovery from a primary M1 lesion targeted to the hand area. Ó

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

“…The number of inactivation/perturbation sessions was kept to a minimum, to avoid motor cortex damage which may compromise the main injury studies. Complementary behavioural data from Mk‐CA and additional histological data from Mk‐DG were reported in recent publications (Kaeser et al., ; Savidan, Kaeser, Belhaj‐Saif, Schmidlin, & Rouiller, ). All procedures, including purchase of monkeys from a recognized supplier and detention conditions at the University of Fribourg, were conducted according to the guidelines edited by the Swiss federal law on animal protection, reviewed and approved by the local ethical committee (“Commission cantonale de surveillance de l'expérimentation animale”), and finally authorized by the competent veterinary authorities (cantonal and federal), under the license number 2014_42_FR.…”

“…At each site, a volume of 0.5–0.55 μl of muscimol solution was infused in about 30 s. The total amount of muscimol delivered in Mk‐CA was 4.75 μg (Table ). The corresponding muscimol infusion parameters were recently reported for Mk‐DG (Savidan et al., ), representing a total amount of 35 μg (Table ).…”

“…Muscimol was infused in the monkey awake (head stabilized), in the hand representation of the left M1 in Mk‐CA and of the right M1 in Mk‐DG, respectively, using a Hamilton syringe and a 30‐Gauge cannula. The concentration of muscimol in the saline solution was 1 μg/μl in Mk‐CA and accidentally 5 μg/μl in Mk‐DG (see also Savidan et al., ). In Mk‐CA, muscimol was intracortically infused along three penetrations (Figure b), at three distinct sites (depths) previously identified with ICMS below the tecapeek grid (below the dura; nine infusion sites in total).…”

“…In Mk‐DG, when the two hemispheres were still intact, cTBS inactivation sessions were conducted in the right M1, including one sham session, within a time window of 3 days (Figure a). Later, the opposite left M1 was mapped and permanently injured for the purpose of another study (Savidan et al., ). Finally, 4 months later, the intact right M1 was mapped with ICMS before conducting a muscimol inactivation session (Figure a), with however an overdose of muscimol (see below).…”

“…Under anaesthesia maintained by endotracheal inhalation of sevoflurane 2.5%, combined with Propofol (0.1 mg kg −1 min −1 ) intravenous infusion (Lanz et al., ), a rectangular Tecapeek chronic chamber was surgically implanted unilaterally above the rostral part of the central sulcus according to topographic coordinates (Shimazu, Maier, Cerri, Kirkwood, & Lemon, ). The chronic chamber includes two squared tecapeek grids containing 49 holes each with a diameter of 500 μm perpendicular to the surface (Figure b), allowing the trans‐dural penetrations with tun microelectrodes (Savidan et al., ; Schmidlin et al., ). ICMS was performed under light sedation maintained with repeated intramuscular injections of ketamine (1.25 mg/kg) combined with medetomidine (0.07 mg/kg).…”