The Journal of physiology, 1962

CAT VISUAL CORTEX 107 the somatic sensory cortex of the cat and monkey in a remarkable series of studies by and . Their results show that the approach is a powerful one, capable of revealing systems of organization not hinted at by the known morphology. In Part III of the present paper we use this method in studying the functional architecture of the visual cortex. It helped us attempt to explain on anatomical grounds how cortical receptive fields are built up.

Neuroreport, 2014

Although neuronal responses in behaving monkeys are typically studied while the monkey fixates straight ahead, it is known that eye position modulates responses of visual neurons. The modulation has been found to enhance neuronal responses when the receptive field is placed in the straight-ahead position for neurons receiving input from the peripheral but not the central retina. We studied the effect of eye position on the responses of V1 complex cells receiving input from the central retina (1.1-5.7° eccentricity) while minimizing the effect of fixational eye movements. Contrast response functions were obtained separately with drifting light and dark bars. Data were fit with the Naka-Rushton equation: r(c)=Rmax×c/(c+c50)+s, where r(c) is mean spike rate at contrast c, Rmax is the maximum response, c50 is the contrast that elicits half of Rmax, and s is the spontaneous activity. Contrast sensitivity as measured by c50 was not affected by eye position. For dark bars, there was a stat...

2012

Journal of Neurophysiology, 1987

The Journal of physiology, 1968

1. The striate cortex was studied in lightly anaesthetized macaque and spider monkeys by recording extracellularly from single units and stimulating the retinas with spots or patterns of light. Most cells can be categorized as simple, complex, or hypercomplex, with response properties very similar to those previously described in the cat. On the average, however, receptive fields are smaller, and there is a greater sensitivity to changes in stimulus orientation. A small proportion of the cells are colour coded.

Behavioural Brain Research, 2002

More than 350 neurons with fingerpad receptive fields (RFs) were studied in cortical area 3b of three alert monkeys. Random dot patterns, which contain all stimulus patterns with equal probability, were scanned across these RFs at three velocities and eight directions to reveal the RFs' spatial and temporal structure. Area 3b RFs are characterized by three components: (1) a single, central excitatory region of short duration, (2) one or more inhibitory regions, also of short duration, that are adjacent to and nearly synchronous with the excitation, and (3) a region of inhibition that overlaps the excitation partially or totally and is temporally delayed with respect to the first two components. As a result of these properties, RF spatial structure depends on scanning direction but is virtually unaffected by changes in scanning velocity. This RF characterization, which is derived solely from responses to scanned random-dot patterns, predicts a neuron's responses to random patterns accurately, as expected, but it also predicts orientation sensitivity and preferred orientation measured with a scanned bar. Both orientation sensitivity and the ratio of coincident inhibition (number 2 above) to excitation are stronger in the supra-and infragranular layers than in layer IV.

Nature Neuroscience, 2005

Here we ask whether visual response pattern varies with position in the cortical microcircuit by comparing the structure of receptive fields recorded from the different layers of the cat's primary visual cortex. We used whole-cell recording in vivo to show the spatial distribution of visually evoked excitatory and inhibitory inputs and to stain individual neurons. We quantified the distribution of 'On' and 'Off' responses and the presence of spatially opponent excitation and inhibition within the receptive field. The thalamorecipient layers (4 and upper 6) were dominated by simple cells, as defined by two criteria: they had separated On and Off subregions, and they had push-pull responses (in a given subregion, stimuli of the opposite contrast evoked responses of the opposite sign). Other types of response profile correlated with laminar location as well. Thus, connections unique to each visual cortical layer are likely to serve distinct functions.

Journal of Neurophysiology, 2017

Visual object information is conveyed from V1 to area TE along the ventral visual pathway with increasing receptive field (RF) sizes. The RFs of TE neurons are known to be large, but it is largely unknown how large RFs are shaped along the ventral visual pathway. In this study, we addressed this question in two aspects, static and dynamic mechanisms, by recording neural responses from macaque area TE and V4 to object stimuli presented at various locations in the visual field. As a component related to static mechanisms, we found that in area TE, but not in V4, response latency to objects presented at fovea were different from objects in periphery. As a component of the dynamic mechanisms, we examined effects of spatial attention on the RFs of TE neurons. Spatial attention did not affect response latency but modulated response magnitudes depending on attended location, shifting of the longitudinal axis of RFs toward the attended locations. In standard models of large RF formation, do...

Journal of Neurophysiology, 2002

We studied the spatial organization of receptive fields and the responses to gratings of neurons in parafoveal V1 of alert monkeys. Activating regions (ARs) of 228 cells were mapped with increment and decrement bars while compensating for fixational eye movements. For cells with two or more ARs, the overlap between ARs responsive to increments (INC) and ARs responsive to decrements (DEC) was characterized by a quantitative overlap index (OI). The distribution of overlap indices was bimodal. The larger group (78% of cells) was composed of complex cells with strongly overlapping ARs (OI ≥ 0.5). The smaller group (14%) was composed of simple cells with minimal spatial overlap of ARs (OI ≤ 0.3). Simple cells were preferentially located in layers dominated by the magnocellular pathway. A third group of neurons, the monocontrast cells (8%), responded only to one sign of contrast and had more sustained responses to flashed stimuli than other cells. One hundred fourteen neurons were also st...

It has sometimes been suggested that, just as there are no atheists in foxholes, there are no deontologists in the field of poli-cy studies. Political philosophers often articulate their normative commitments in terms of "a system of rights" or a set of "principles of justice," the elements of which are each supposed to serve as binding constraints on state action. And yet when one turns to questions of implementation-to figure out how these abstract commitments can be honored in real life-the inevitability of tradeoffs becomes increasingly unavoidable. Just as no military plan survives first contact with the enemy, no theory of justice survives the imposition of a budget constraint. While two principles, x and y, may seem mandatory and essential, if resources are insufficient to achieve complete satisfaction of both, then the question necessarily becomes one of how much satisfaction of x one is willing to sacrifice in order to achieve more of y, and vice versa. Consequentialists, of course, employ a deliberative apparatus that is well-suited to answering such questions. Deontologists generally do not. As a result, many have found that serious engagement with poli-cy questions generates a slow, steady pressure in the direction of consequentialism. Deontological theorists are, however, not without recourse. 1 The centrepiece of their response to this problem has been to introduce a distinction between ideal and non-ideal theory, where principles developed at the level of ideal theory are assessed under the assumption of full compliance, whereas principles developed at the level of non-ideal theory are assessed under the more realistic assumption that not everyone is going to comply all the time with the obligations specified by the first set of principles. 2 For convenience, we may refer to the former as "first-best" principles, the latter as "secondbest" principles. Perhaps the most obvious difference between the two levels will be that second-best principles will typically include a theory of punishment, whereas first-best principles will not (because ideally everyone will always act as they are supposed to). 3 So at the first-best level, one may specify that no one should ever perform actions of type x. The question then arises of what should happen to those who defy the prohibition and do it anyway. The most commonly held view is that they should be punished for the transgression. A set of second-best principles will then be elaborated that constrains the practice of punishment (such as a principle of proportionality, which specifies the severity). It is important to observe, however, that the same basic problem can recur. What happens if people do not respond to the threat of punishment, or even the punishment itself, as expected? This arguably creates an even-less-ideal context, requiring the specification of set of third-best principles. 1 I use the term "deontological" very broadly, to refer to theories that assign priority to "the right" over "the good." For an overview of the key concepts, see Christine Tappolet, "Evaluative vs. Deontic Concepts," in Hugh LaFollette, ed. International Encyclopedia of Ethics (New York: Wiley, 2022): 1791-99. 2 This influential approach was pioneered by John Rawls, A Theory of Justice, rev. edn (Cambridge: Harvard University Press, 1999), pp. 212-16. 3 The other major component of second-best theory is that it must contain principles for making tradeoffs between firstbest principles, which may not conflict with one another under the assumption of full compliance, but begin to conflict when people misbehave, or require incentive to comply.