Follow-up of cortical activity and structure after lesion with laser speckle imaging and magnetic resonance imaging in nonhuman primates

Abstract

Abstract. The nonhuman primate model is suitable to study mechanisms of functional recovery following lesion of the cerebral cortex (motor cortex), on which therapeutic strategies can be tested. To interpret behavioral data (time course and extent of functional recovery), it is crucial to monitor the properties of the experimental cortical lesion, induced by infusion of the excitotoxin ibotenic acid. In two adult macaque monkeys, ibotenic acid infusions produced a restricted, permanent lesion of the motor cortex. In one monkey, the lesion was monitored over 3.5 weeks, combining laser speckle imaging (LSI) as metabolic readout (cerebral blood flow) and anatomical assessment with magnetic resonance imaging (T2-weighted MRI). The cerebral blood flow, measured online during subsequent injections of the ibotenic acid in the motor cortex, exhibited a dramatic increase, still present after one week, in parallel to a MRI hypersignal. After 3.5 weeks, the cerebral blood flow was strongly reduced (below reference level) and the hypersignal disappeared from the MRI scan, although the lesion was permanent as histologically assessed post-mortem. The MRI data were similar in the second monkey. Our experiments suggest that LSI and MRI, although they reflect different features, vary in parallel during a few weeks following an excitotoxic cortical lesion. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Rapid high resolution imaging of diffusive properties in turbid media

“…Microsecond acquisition times will however additionally demand a fast and sensitive camera as well as sufficient laser power. [20]. Sample also shows a slight intensity contrast -not shown -due to the finite reflectivity of the correction tape.…”

“…Figure 6 shows a contrast map [20] of white paper (l * 11 ± 1 μm), the right side of which is covered with correction tape (l * ≈1-2 μm) with part of the correction tape removed (single scratch). The spatially averaged l * of paper and correction tape were determined using DWS.…”

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

“…After reaching the plateau of behavioral performances, 17 weeks and 3 days after the primary lesion, a second MRI scan was performed to localize the lesion and its extent, following a similar procedure as the first MRI scan during the PreL (see also Peuser et al, 2011). The MRI acquisitions were done under anesthesia, induced with a mixture of ketamine (KetasolÒ 10 mg/kg; i.m.)…”

“…Following a ''learning" period in order to reach a stable performance (see Chatagny et al, 2013;Kaeser et al, 2014), 3 months of pre-lesion behavioral data were collected. During this pre-lesion period (PreL), a structural MRI of reference was acquired (method described in Peuser et al, 2011); in addition, a chronic chamber and epidural grid were implanted over the M1 hand area on the left hemisphere. Once the monkey recovered from the surgery, the behavioral tasks resumed.…”

Principles and Fundamentals of Optical Imaging

“…illumination usually applied. Additional complications, specifi c to LSI and not present in OIS, are the limited signal to noise ratio and the sensitivity of the method to vibrations and body movements, for example, due to breathing and heartbeat [ 43 ].…”