Imaging cortical electrical stimulation in vivo: fast intrinsic optical signal versus voltage-sensitive dyes

Abstract

We applied high-temporal-resolution optical imaging utilizing both the fast intrinsic optical signal (fIOS) and voltage-sensitive dyes (VSDs) to observe the spatiotemporal characteristics of rat somatosensory cortex during electrical stimulation. We find that changes in both the fIOS and VSD signals occur rapidly (<30 ms) after the stimulus is applied, suggesting that both membrane depolarization and transmembrane ion movement occur shortly after the stimulus, preceding the more gradual physiological changes in oxygen consumption revealed by the slower component of the intrinsic optical signal. We find that the VSD signal spreads through a much larger area of cortex than the fIOS.

Intrinsic optical imaging of directional selectivity in rat barrel cortex: Application of a multidirectional magnetic whisker stimulator

“…In the work described in the present paper, we take a first step toward mapping the somatotopic structure of the barrel cortex using the intrinsic optical signal. Higher resolution imaging techniques, such as voltage sensitive dye imaging (Tsytsarev et al, 2008), however, will be essential for the full investigation of the more subtle sensitivities investigated (Andermann and Moore, 2006). These issues include distinguishing between the correlated vs. uncorrelated hypotheses (i.e., whether directional preference is biased toward a neuron's nearest somatotopic neighbor, or away from it), and the observation of a preference for sensitivity to the rostral-caudal direction.…”

Study of the cortical representation of whisker directional deflection using voltage-sensitive dye optical imaging

“…All animals were initially anesthetized with intraperitoneal ketamine (90 mg/kg, Hospira) and xylazine (2.0 mg/kg body weight, i.m., Hospira) and then sustained with urethane (1.25 g/kg), and furosemidae sulfate (0.1 mg/kg body weight, i.m., Hospira) (Tsytsarev et al, 2008). Body temperature was maintained at 37°C with a heating blanket (Harvard Apparatus, Holliston, MA).…”

“…For initial optical imaging, we constructed a functional map using first frame analysis as defined above for each individual trial (Tsytsarev et al, 2008) and then averaging the data for each stimulus. As a result we received an image of the activated area in each frame as a response to each stimulus ( Fig.…”

High-dynamic-range fluorescence laminar optical tomography (HDR-FLOT)

“…Increasing the penetration depth would broaden the application of FLOT for neuroscience research. Since the optical properties of the living mouse brain are too complicated to mimic using a simple phantom, a 150-μm glass capillary filled with voltage-sensitive dye (commonly used for reporting neural activities [6, [32][33][34][35]) was inserted into a mouse brain in vivo to demonstrate the feasibility of HDR-FLOT to increase penetration depth.…”