Laser-induced accurate frontal cortex damage: a new tool for brain study

New laser-based technique for anatomical-functional study of the medial prefrontal cortex (MPFC) of the brain of experimental animals (rats) is presented. The technique is based on making accurate well-controlled lesions to small MPFC and subsequent observing behavioral alterations in the lesioned animals relative to control ones. Laser produces smaller and more accurate lesions in comparison to those obtained by traditional methods, such as: mechanical action, chemical means, and electrical currents. For producing the brain lesions, a 10 W CO2 CW laser is employed for reasons of its sufficiently high power, which is combined with relatively low cost-per-Watt ratio. In our experience, such power rating is sufficient for making MPFC lesions. The laser radiation is applied in a form of pulse series via hollow circular metallic waveguide made of stainless steel. The waveguide is of inner diameter 1.3 mm and 95 mm long. The anesthetized animals are placed in stereotaxic instrument. Via perforations made in the skull bone, the MPFC is exposed to the laser radiation. Several weeks later (after animal recuperation), standard behavioral tests are performed. They reveal behavioral changes, which point to a damage of some small regions of the MPFC. These results correlate with the histological data, which reveal the existence of small and accurate MPFC lesions. The present technique has good prospects for use in anatomical- functional studies of brain by areas. In addition, this technique appears to have considerable promise as a treatment method for some pathologies, e.g. the Parkinson's disease.