Table of Contents

Giorgio Ascoli, Editor

# Chapter 8:

### Predicting emergent properties of neuronal ensembles using a database of individual neurons, by Gwen A. Jacobs, Ph. D. and Colin S. Pittendrigh

Legends for color images and animation:

Figure 2_color_image:
3D reconstructions of individual neurons. A. An image from the database, showing a dorsal view of four different reconstructed neurons. Three of the neurons are primary sensory afferents, the fourth neuron is a primary sensory interneuron, whose axon projects anterior to higher centers of the nervous system. The axons of the sensory neurons have been labeled with arrow heads. All neurons have been scaled and aligned to the database and are shown in their correct spatial relationships to each other. Each of the sensory neurons has been color coded according to it's peak directional tuning in body coordinates. The inset shows a color wheel indicating air current direction in body coordinates. Yellow indicates air currents directed at the animal's head in the horizontal plane. B. Inset shows four neurons in A with an outline of the terminal abdominal ganglion. Scale bar: 40 microns

Figure 4: color image:
Functional representation of two different stimulus parameters within a neural map. A. Combined image of the entire ensemble of sensory neurons which innervate the filiform mechanoreceptor hairs on the left cercus shown in parasaggital view. The viewing plane has been rotated along the X axis to illustrate several functional aspects of the neural map. Axes have been labeled x, y or z to indicate orientation in 3D space. Each colored cloud represents a population of sensory neurons tuned to a specific air current direction in body coordinates. Sensory cells tuned to similar air current directions overlap anatomically. Note that the directional tuning of the sensory afferents changes in a continuous fashion along a circular contour. Inset: The color wheel corresponds to the peak directional tuning in body coordinates; yellow indicates air currents directed at the animal's head in the horizontal plane. B. Same population of sensory neurons as shown in A color coded according to frequency tuning. Sensory neurons tuned to low frequencies are colored red and neurons tuned to higher stimulus frequencies are colored green. Note the lack of anatomical segregation between the two populations of sensory neurons. Scale bar: The distance between ticks on the cross hairs is 40 microns.

Figure 6_color_animation:
Predictions of dynamic patterns of activity within the neural map. This animation shows a sequence of activity patterns within the map in response to a predicted 100 Hz sine wave air current which alternates direction back and forth across the animal's body. The direction of the stimulus is encoded by two different activity patterns: a horseshoe shaped pattern when the stimulus is directed at the left side of the animal's body followed by a "C" shaped pattern when the air current changes direction towards the animal's lower right. Each image shows the relative contribution of sensory neurons tuned to low frequencies (red clouds) and sensory neurons tuned to higher frequencies (green clouds). Note that at some phases of the activity pattern both sets of afferents tuned to the same directions are activated together and at other phases cells tuned to opposite directions are activated together. The animation shows the predicted spatio-temporal pattern of activity that would result from this dynamic stimulus.

Figure 7 color image:
Prediction of excitatory inputs to an identified interneuron. The images represent a quantitative prediction of the spatial distribution of excitatory inputs to the interneuron, color coded according to the peak directional tuning of the sensory neurons. In the top panel, a primary sensory interneuron has been superimposed over the map, illustrating the spatial location of it's dendrites with respect to specific regions of the neural map. In the bottom image the interneuron's dendrites have been color coded according to their spatial location within the map and the distribution of excitatory inputs to the dendrites. The images represent a quantitative prediction of the spatial distribution of excitatory inputs to the interneuron.