Receptive field

It is interesting that the stimulus compounds used in the study differ widely in their molecular structures, and yet they all interact with antibodies to thaumatin. It is, therefore, probable that a single receptor-structure responds to all sweet stimuli,there being a variation in the relative effectiveness of sweet stimuli across individual nerve-fibers, and the characteristics of all receptor sites do not appear to be identical. Earlier elec-trophysiological studies of single primary, afferent taste-neurons uniformly agreed that individual fibers very often have multiple sensitivities, and that individual, gustatory receptors are part of the receptive field of more than one afferent fiber. " We have yet to learn how these interact, and the nature of their excitatory, or possible inhibitory, relations, or both. 

Of the several approaches that draw upon this general description, radial basis function networks (RBFNs) (Leonard and Kramer, 1991) are probably the best-known. RBFNs are similar in architecture to back propagation networks (BPNs) in that they consist of an input layer, a single hidden layer, and an output layer. The hidden layer makes use of Gaussian basis functions that result in inputs projected on a hypersphere instead of a hyperplane. RBFNs therefore generate spherical clusters in the input data space, as illustrated in Fig. 12. These clusters are generally referred to as receptive fields. 

Variations on RBFNs have been developed that project the inputs on hyperellipses instead of hyperspheres. These ellipsoidal basis function networks allow nonunity and unequal input weights, except zero and negative values, causing elongation and contraction of the spherical receptive fields into ellipsoidal receptive fields (Kavuri and Venkatasubramanian, 1993). 

The extent of the branching displayed by the dendrites is a useful index of their functional importance. Dendritic trees represent the expression of the receptive fields, and large fields can receive inputs from multiple origins. A cell with a less developed dendritic ramification, such as the cerebellar granule cell, has synapses with a more homogeneous population of afferent sources. 

The biochemical neuron has another role as a transducer of external analog signals to impulse signals, where the external signals are received at the receptive field and transduced to impulse signals by cutting off at a certain threshold value. 

Edeline JM (1999) Learning-induced physiological plasticity in the thalamo-cortical sensory systems a critical evaluation of receptive field plasticity, map changes and their potential mechanisms. Prog Neurobiol 57 165-224... 

Hosl, M. (1990). Pheromone-sensitive neurons in the deutocerebrum of Periplaneta americana receptive fields on the antenna. Journal of Comparative Physiology A 167 321-327. 

Figure 2.11 A simple cell responds to lines or edges oriented at a particular orientation. It may be constructed by receiving input from several of the center-surround neurons found in the lateral geniculate nucleus. (Reproduced from D. H. Hubei and T. N. Wiesel. Receptive fields, binocular interaction and functional architecture in the cat s visual cortex. Journal of Physiology, Vol. 160, pp. 106-154, 1962, by permission of Blackwell Publishing, UK.)...

Most cells of the interblob region respond to lines or bars of a particular orientation. They do not respond to color or show any color opponency. In contrast to the cells found inside the blobs, the receptive field of the cells found in the interblob region is very small. The response characteristic of the neurons of the interblob regions is arranged... 

The receptive field of the cells found in V4 is quite large. The corpus callosum connects both hemispheres of the brain. Since the corpus callosum also plays a role in color perception (see Section 2.6) and V4 also has connections with the corpus callosum, it is the first possible area where color constant cells can occur. As we will see later on, the entire scene plays an important role in color perception. The perceived color of a point is dependent not only on the light reflected from that point but also on the light that is reflected from the surrounding area (Judd 1960). It also depends on the colors seen previously by the same observer. 

Figure 2.16 Motion selective cell. The receptive field of the cell is shown on the left. The cell only responds to motion in a preferred direction. (Reproduced from S. Zeki. An Exploration of Art and the Brain. Oxford University Press, Oxford, 1999 by permission of S. Zeki, University College London, UK.)...

Huhel DH and Wiesel TN 1962 Receptive fields, binocular interaction and functional architecture in the cat s visual cortex. Journal of Physiology 160, 106-154. 

Schiele B and Crowley JL 1996 Object recognition using multidimensional receptive field histograms In Fourth European Conference On Computer Vision, Cambridge, UK, April 14-18 (eds. Buxton B and Cipolla R), pp. 610-619. Springer-Verlag, Berlin. 

Schiele B and Crowley JL 2000 Recognition without correspondence using multidimensional receptive field histograms. International Journal of Computer Vision 36(1), 31-52. 

Reproduced from D. H. Hubei and T. N. Wiesel. Receptive fields,... 

Kaplan E. 1991. The receptive field structure of retinal ganglion cells in cat and monkey. Vision and Visual... 

Zhou, Y., Wang, W., Ren, B., and Shou, T., 1994, Receptive field properties of cat retinal ganglion cells during short-term IOP elevation. Invest. Ophthalmol. Vis. Sci. 35(6) 2758-2764. 

Fig. 7 Antagonistic center/surround interaction is the basic model of a foveal retinal ganglion cell receptive field. Note that the center mechanism is characterized by a narrow and tall response (sensitivity) profile, whereas the surround is broad and has a low, spatially extended profile. The response profiles are established by preganghonic circuitry. The ganglion cell performs the linear operation of subtracting the center and surround signals. If the surround mechanism is selectively attenuated it may lead to a response that monotonically grows with center stimulation. As a result the spatial transfer function loses tuning. The exact spatial frequency at which tuning occurs reflects on the diameter and optimal interplay between center and surround (after Enroth-CugeU and Robson, 1966)...

Figure 2. Taste systems of the rat geniculate (GG) and petrosal (PG) ganglia. Location of receptive fields indicated by a dot on tongue for each neuron studied. Examples are shown of elicited spike discharge for neurons from the six different neural groups identified.

In contrast to M cells, P cells have small cell bodies with small dendritic arborizations resulting in small receptive fields. P cells are also wavelength-selective. P cell output thus contributes to fine feature analysis and color vision. P cells are classified anatomically as midget ganglion cells. 

Edge Detection and Center-Sunround Receptive Fields... 

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