The intrinsic imaging system serves as a monitoring tool before or during in vivo experiments. It is optimized for invasively localizing the brain areas or the spinal cord which are activated during different stimuli or combinations of stimuli.
Before the two-photon imaging, using traditional intrinsic imaging technique helps to find the location of maximal functional responses through the intact skull. The technique is based on the measurement of the intrinsic differences in light absorbance between the oxy and deoxy forms of hemoglobin. Stimulus-induced neural activity increases oxyhemoglobin concentration thereby the light absorption, so the activated areas appear as darker regions (BOLD signal).
Intrinsic imaging in the V1 area of the visual cortex during moving grating visual stimulation followed by Intrinsic Imaging System. Figures show the activated darker (or red on the lower figure) regions as intrinsic responses as a function of time.
Femtonics’s Intrinsic Imaging System provides precise, functional guidance for targeting the region of interest before the cranial window is opened. This can be especially convenient to locate higher order sensory areas which often can be rather difficult using the anatomical position only. The system is available as a stand-alone system or can be fully integrated into any Femtonics microscope to present an additional feature right on the spot offering the option to use it at any time during an experiment.
The wavelength of the LEDs in the system is selected to have the highest change in absorbance between different forms of hemoglobin. This reduces the time necessary for imaging and decreases the natural noise caused by the long term changes in the brain state. Due to the improved image quality the system can dissolve the activity not only spatially but also temporally with less than 1s resolution. This helps the identification of sequentially activated brain regions and identifies higher order sensory regions.
MES’s Intrinsic software module is used to evaluate the activity-related intrinsic signals. Stimulation evoked signals can be added by StimVisual software module. StimVisual allows loading visual stimulus and other stimuli can be triggered such as tactile, whisker, auditory or odor stimuli. For stimulate the visual cortex with different set of visual stimulations, we also recommend to use our video projector system as imput system.