What chiefly distinguishes cerebral cortex from other parts of the central nervous system is the great diversity of its cell types and interconnexions. It would be astonishing if such a structure did not profoundly modify the response patterns of fibres coming into it. In the cat's visual cortex, the receptive field arrangements of single cells suggest that there is indeed a degree of complexity far exceeding anything yet seen at lower levels in the visual system. In a previous paper we described receptive fields of single cortical cells, observing responses to spots of light shone on one or both retinas (Hubel & Wiesel, 1959). In the present work this method is used to examine receptive fields of a more complex type (Part I) and to make additional observations on binocular interaction (Part II). This approach is necessary in order to understand the behaviour of individual cells, but it fails to deal with the problem of the relationship of one cell to its neighbours. In the past, the technique of recording evoked slow waves has been used with great success in studies of functional anatomy. It was employed by Talbot & Marshall (1941) and by Thompson, Woolsey & Talbot (1950) for mapping out the visual cortex in the rabbit, cat, and monkey. Daniel & Whitteiidge (1959) have recently extended this work in the primate. Most of our present knowledge of retinotopic projections, binocular overlap, and the second visual area is based on these investigations. Yet the method of evoked potentials is valuable mainly for detecting behaviour common to large populations of neighbouring cells; it cannot differentiate functionally between areas of cortex smaller than about 1 mm2. To overcome this difficulty a method has in recent years been developed for studying cells separately or in small groups during long micro-electrode penetrations through nervous tissue. Responses are correlated with cell location by reconstructing the electrode tracks from histological material. These techniques have been applied to

Receptive fields, binocular interaction and functional architecture in the cat's visual cortex

▪ Abstract Synaptic transmission is a dynamic process. Postsynaptic responses wax and wane as presynaptic activity evolves. This prominent characteristic of chemical synaptic transmission is a crucial determinant of the response properties of synapses and, in turn, of the stimulus properties selected by neural networks and of the patterns of activity generated by those networks. This review focuses on synaptic changes that result from prior activity in the synapse under study, and is restricted to short-term effects that last for at most a few minutes. Forms of synaptic enhancement, such as facilitation, augmentation, and post-tetanic potentiation, are usually attributed to effects of a residual elevation in presynaptic [Ca2+]i, acting on one or more molecular targets that appear to be distinct from the secretory trigger responsible for fast exocytosis and phasic release of transmitter to single action potentials. We discuss the evidence for this hypothesis, and the origins of the different kinetic phases...

/pdf/short-term-synaptic-plasticity-5d4dx79319.pdf

Short-Term Synaptic Plasticity

In the central nervous system the visual pathway from retina to striate cortex provides an opportunity to observe and compare single unit responses at several distinct levels. Patterns of light stimuli most effective in influencing units at one level may no longer be the most effective at the next. From differences in responses at successive stages in the pathway one may hope to gain some understanding of the part each stage plays in visual perception. By shining small spots of light on the light-adapted cat retina Kuffler (1953) showed that ganglion cells have concentric receptive fields, with an 'on' centre and an 'off ' periphery, or vice versa. The 'on' and 'off' areas within a receptive field were found to be mutually antagonistic, and a spot restricted to the centre of the field was more effective than one covering the whole receptive field (Barlow, FitzHugh & Kuffler, 1957). In the freely moving lightadapted cat it was found that the great majority of cortical cells studied gave little or no response to light stimuli covering most of the animal's visual field, whereas small spots shone in a restricted retinal region often evoked brisk responses (Hubel, 1959). A moving spot of light often produced stronger responses than a stationary one, and sometimes a moving spot gave more activation for one direction than for the opposite. The present investigation, made in acute preparations, includes a study of receptive fields of cells in the cat's striate cortex. Receptive fields of the cells considered in this paper were divided into separate excitatory and inhibitory ('on' and 'off') areas. In this respect they resembled retinal ganglion-cell receptive fields. However, the shape and arrangement of excitatory and inhibitory areas differed strikingly from the concentric pattern found in retinal ganglion cells. An attempt was made to correlate responses to moving stimuli

http://hubel.med.harvard.edu/papers/HubelWiesel1959JPhysiol.pdf

Receptive fields of single neurones in the cat's striate cortex

Introduction to synaptic circuits, Gordon M.Shepherd and Christof Koch membrane properties and neurotransmitter actions, David A.McCormick peripheral ganglia, Paul R.Adams and Christof Koch spinal cord - ventral horn, Robert E.Burke olfactory bulb, Gordon M.Shepherd, and Charles A.Greer retina, Peter Sterling cerebellum, Rodolfo R.Llinas and Kerry D.Walton thalamus, S.Murray Sherman and Christof Koch basal ganglia, Charles J.Wilson olfactory cortex, Lewis B.Haberly hippocampus, Thomas H.Brown and Anthony M.Zador neocortex, Rodney J.Douglas and Kevan A.C.Martin Gordon M.Shepherd. Appendix: Dendretic electrotonus and synaptic integration.

The synaptic organization of the brain

Anatomical and physiological observations in monkeys indicate that the primate visual system consists of several separate and independent subdivisions that analyze different aspects of the same retinal image: cells in cortical visual areas 1 and 2 and higher visual areas are segregated into three interdigitating subdivisions that differ in their selectivity for color, stereopsis, movement, and orientation. The pathways selective for form and color seem to be derived mainly from the parvocellular geniculate subdivisions, the depth- and movement-selective components from the magnocellular. At lower levels, in the retina and in the geniculate, cells in these two subdivisions differ in their color selectivity, contrast sensitivity, temporal properties, and spatial resolution. These major differences in the properties of cells at lower levels in each of the subdivisions led to the prediction that different visual functions, such as color, depth, movement, and form perception, should exhibit corresponding differences. Human perceptual experiments are remarkably consistent with these predictions. Moreover, perceptual experiments can be designed to ask which subdivisions of the system are responsible for particular visual abilities, such as figure/ground discrimination or perception of depth from perspective or relative movement--functions that might be difficult to deduce from single-cell response properties.

https://science.sciencemag.org/content/sci/240/4853/740.full.pdf

Segregation of form, color, movement, and depth: anatomy, physiology, and perception

THE DISCHARGES carried in the optic nerve fibers contain all the information which the central nervous system receives from the retina. A correct interpretation of discharge patterns therefore constitutes an important step in the analysis of visual events. Further, investigations of nervous activity arising in the eye reveal many aspects of the functional organization of the neural elements within the retina itself. Following studies of discharges in the optic nerve of the eel’s eye by Adrian and Matthews (2,3), Hartline and his colleagues described the discharge pattern in the eye of the Limulus in a series of important and lucid papers (for a summary see 20). In the Limulus the relationship between the stimulus to the primary receptor cell and the nerve discharges proved relatively simple, apparently because the connection between sense cell and nerve fiber was a direct one. Thus, when stimulation is confined to one receptor the discharge in a single Limulus nerve fiber will provide a good indication of excitatory events which take place as a result of photochemical processes. Discharges last for the duration of illumination and their frequency is a measure of stimulus strength. Lately, however, it was shown by Hartline et al. (22) that inhibitory interactions may be revealed when several receptors are excited. On the whole, the Limulus preparation shows many features which are similar to other simple sense organs, for instance, stretch receptors. In the latter, however, instead of photochemical events, stretch-deformation acts as the adequate stimulus on sensory terminals and is translated into a characteristic discharge pattern. The discharge from the cold-blooded vertebrate retina (mainly frogs) proved much more complex. Hartline found three main types when recording from single optic nerve fibers: (i) “on” discharges, similar to those in the Limulus, firing for the duration of the light stimulus, (ii) “off” discharges appearing when a light stimulus was withdrawn, and (iii) ‘con-off” discharges, a combination of the former two, with activity confined mainly to onset and cessation of illumination. The mammalian discharge patterns were studied in a number of species by Granit and his co-workers in the course of their extensive work on the physiology of the visual system (summaries in 13, 15). On the whole, they did not observe any fundamental differences between frog and mammalian discharge types (see later).

Discharge patterns and functional organization of mammalian retina

NEURONS AND G .LIAL CELLS in most parts of the nervo us system are intimately apposed, separated from each other by channels about 150 A. wide. It is natural to wonder whether the two types of cell influence one another either “electrically” (i.e., by current flow from one cell to the other) or by the release of a substance. It has been shown in the leech nervous system that if current is supplied to the interior of a nerve cell through an intracellular electrode, very little will enter the neighboring glial cell; most will pass through the intercellular clefts which have a relatively low resistance. Similarly, currents which flow during nerve impulses alter the membrane potential of the surrounding glia to a negligible extent good agreement with subsequent findings that the (10) clefts These results were in l between neurons and glial cells served as channels for the rapid diffusion of ions and of small molecules both in the leech and in amphibia (l&9). In the central nervous system of the leech, which contains smooth muscle cells in its connective tissue capsule, the effect of massive neuronal activity on the resting potential of glial cells could not be studied adequately because the preparation under these conditions and dislodged the electrode (1 0) . moved

Stephen W. Kuffler

Papers

Discharge patterns and functional organization of mammalian retina

Effect of nerve impulses on the membrane potential of glial cells in the central nervous system of amphibia.

Change of organization in the receptive fields of the cat's retina during dark adaptation

Physiological properties of glial cells in the central nervous system of amphibia.

Glia in the leech central nervous system: physiological properties and neuron-glia relationship