Jianyoung Wu's Lab
Propagating Waves in Neocortical Slices:
The movies show waves of neuronal activity in tangential slices of rat occipital cortex. The slices were stained with voltage-sensitive dye (NK3630) and the dye changes its color (absorption) when the transmembrane potential of the neurons are changed. Imaging was performed by a 464 element photodiode array at a rate of 1600 frames /sec. The oscillations (4 - 12 Hz) were induced by perfusing slices with 100 mM carbachol and 10 mM bicuculline. The optical signal on each optical detector is a summation of depolarization/hyperpolarization of about 1,000 neurons. The optical signal of the oscillations was about 0.01% of the resting light intensity. The signal on each detector is normalized to its own max-min and assigned to a color according to a linear color scale (on the top of the image). The oscillations were organized spatially as propagating waves. All wave patterns shown in the movies were formed spontaneously without manipulations. Imaging apparatus and the methods are described in detail in Wu and Cohen (1993), Wu et al., (1999), and Jin et al. (2002) and Bao and Wu 2003 (see my publication page for full reference).
This movie shows wave patterns during a period of about 600 ms of oscillations with 6 cycles of oscillations. The bottom trace is the activity on one optical detector located near the center of the image (marked by a small box). The small red square sliding on the bottom trace indicates the time of the current image of the movie. Each oscillation cycle is associated with three plane waves started from the edges of the slice (about 4 x 6 mm) and collided near the center of the imaging field. These three waves occurred spontaneously at the edge of the field without stimulation. The slice is about 4 x 6 mm and the image field is 3 mm in diameter covering the center of the slice.
This movie shows ring-shaped waves started at the upper left quadrant of the view field. In this period many cycles (21 were shown) started from the same location. The field of view is the same as the one for Movie 1. The wave patterns and the initiation site of the waves are, however, very different from that of Movie 1, suggesting that the wave pattern and initiation points are dynamically organized.
This movie shows waves with two spiral patterns. The slice is about 4 x 6 mm and the image field is 3 mm in diameter covering the center of the slice. The rest are the same as Movie 1 and 2.
Movie 4 is from a coronal slice, about 3 mm long and 1.5 mm wide. The orientation of the slice is shown in Figure 5 left (main article). Movie 5 is from a tangential slice, about 3 mm in diameter. The orientation of the slice is shown in Figure 7B left (main article). The signal amplitude is color coded according to a linear pseudo-color scale (top left, peak to red and valley to blue, peak to valley equivalent to 4 x 10-4 for Movie 4 and 2 x 10-4 for Movie 5 respectively). The frame rate is 1600 frames/sec for both movies. When playing at normal speed of 30 frame/second, the movies are about 50 times slower than the real events. The bottom right panel is the VSD signal from one optical detector. The location of the detector is marked by a black box in the movie image. When playing the movies, a red dot is flying on the trace, indicating the time of the current frame. The Movie 4 is made from the same slice used in Figure 5 (different trial). The Movie 5 is made from the same slice used in Figure 7B (different trial).