Receptive field

About: Receptive field is a research topic. Over the lifetime, 8537 publications have been published within this topic receiving 596428 citations.

Two Distinct Mechanisms of Suppression in Human Vision

Abstract: Cortical visual neurons in the cat and monkey are inhibited by stimuli surrounding their receptive fields (surround suppression) or presented within their receptive fields (cross-orientation or overlay suppression). We show that human contrast sensitivity is similarly affected by two distinct suppression mechanisms. In agreement with the animal studies, human surround suppression is tightly tuned to the orientation and spatial frequency of the test, unlike overlay suppression. Using a double-masking paradigm, we also show that in humans, overlay suppression precedes surround suppression in the processing sequence. Surprisingly, we find that, unlike overlay suppression, surround suppression is only strong in the periphery (>1° eccentricity). This result argues for a new functional distinction between foveal and peripheral operations.

Visual space is compressed in prefrontal cortex before eye movements

Abstract: Saccadic eye movements cause substantial shifts in the retinal image as we take in visual scenes, but our perception is stable and continuous; here, visual receptive fields are shown to shift dramatically towards the saccadic goal, running counter to the long-standing hypothesis of receptive field remapping as the basis of perceived stability. As we take in a visual scene we make rapid eye movements — called saccades — that bring different parts of the scene to the fovea, the region of the retina with highest acuity. These eye movements cause substantial shifts in the retinal image, but our perception of the visual world is stable and continuous. Tirin Moore and colleagues find a possible mechanism for this stability in prefrontal neurons. They show that during preparation for eye movement, neurons shift their visual receptive fields (those regions of space that neurons are most responsive to) in order to massively over-represent behaviourally relevant areas, consistent with human visual perception. These findings run counter to a long-standing hypothesis — that receptive fields predictively remap, shifting the representation of visual space by neurons in the brain in anticipation of the outcome of each eye movement. We experience the visual world through a series of saccadic eye movements, each one shifting our gaze to bring objects of interest to the fovea for further processing. Although such movements lead to frequent and substantial displacements of the retinal image, these displacements go unnoticed. It is widely assumed that a primary mechanism underlying this apparent stability is an anticipatory shifting of visual receptive fields (RFs) from their presaccadic to their postsaccadic locations before movement onset1. Evidence of this predictive ‘remapping’ of RFs has been particularly apparent within brain structures involved in gaze control2,3,4. However, critically absent among that evidence are detailed measurements of visual RFs before movement onset. Here we show that during saccade preparation, rather than remap, RFs of neurons in a prefrontal gaze control area massively converge towards the saccadic target. We mapped the visual RFs of prefrontal neurons during stable fixation and immediately before the onset of eye movements, using multi-electrode recordings in monkeys. Following movements from an initial fixation point to a target, RFs remained stationary in retinocentric space. However, in the period immediately before movement onset, RFs shifted by as much as 18 degrees of visual angle, and converged towards the target location. This convergence resulted in a threefold increase in the proportion of RFs responding to stimuli near the target region. In addition, like in human observers5,6, the population of prefrontal neurons grossly mislocalized presaccadic stimuli as being closer to the target. Our results show that RF shifts do not predict the retinal displacements due to saccades, but instead reflect the overriding perception of target space during eye movements.

Nonlinear summation of M- and L-cone inputs to phasic retinal ganglion cells of the macaque

Abstract: We have studied the responses of ganglion cells in the macaque retina to stimuli that alternate in color. With most color combinations, the phasic retinal ganglion cells, which sum input from M- and L-cones in both center and surround, showed a response with twice the alternation frequency at equal luminance. This frequency doubling was directly related to the degree to which the M- and L-cones were stimulated out-of-phase with one another, and thus varied with the wavelength combinations used. It was absent with wavelength combinations that lay along tritanopic confusion lines, when at equal luminance the M- and L-cones are not modulated. Such a frequency-doubled response is evidence for a nonlinearity at or before M- and L-cone summation. The effect became much smaller or was abolished when the receptive field center alone was stimulated, indicating that its mechanism lies in the surround or in a center-surround interaction. Also, it was much more marked at high luminance levels, being almost absent at retinal illuminances below 100 td. Its origin is not clear, but it seems to derive more from the L- than the M-cone. The results imply that phasic cells, through this nonlinearity, could respond to the red-green equal luminance borders used in some psychophysical experiments.

Mapping a complete neural population in the retina.

Abstract: Recording simultaneously from essentially all of the relevant neurons in a local circuit is crucial to understand how they collectively represent information. Here we show that the combination of a large, dense multielectrode array and a novel, mostly automated spike-sorting algorithm allowed us to record simultaneously from a highly overlapping population of >200 ganglion cells in the salamander retina. By combining these methods with labeling and imaging, we showed that up to 95% of the ganglion cells over the area of the array were recorded. By measuring the coverage of visual space by the receptive fields of the recorded cells, we concluded that our technique captured a neural population that forms an essentially complete representation of a region of visual space. This completeness allowed us to determine the spatial layout of different cell types as well as identify a novel group of ganglion cells that responded reliably to a set of naturalistic and artificial stimuli but had no measurable receptive field. Thus, our method allows unprecedented access to the complete neural representation of visual information, a crucial step for the understanding of population coding in sensory systems.

Topography and nociceptive receptive fields of climbing fibres projecting to the cerebellar anterior lobe in the cat

Abstract: 1. The cutaneous receptive fields of 225 climbing fibres projecting to the forelimb area of the C3 zone in the cerebellar anterior lobe were mapped in the pentobarbitone-anaesthetized cat. Responses in climbing fibres were recorded as complex spikes in Purkinje cells. 2. A detailed topographical organization of the nociceptive climbing fibre input to the C3 zone was found. In the medial C3 zone climbing fibres with receptive fields covering proximal and/or lateral parts of the forelimb projected most medially. Climbing fibres with receptive fields located more medially on the forelimb projected successively more laterally. The sequence of receptive fields found in the lateral C3 zone was roughly the reverse of that in the medial C3 zone. Climbing fibres with receptive fields restricted to the digits projected preferentially to the caudal part of the forelimb area, whereas those with receptive fields covering both proximal and ventral areas of the forearm projected to more rostral parts. 3. The representation of the forelimb was uneven. Receptive fields with a focus on the digits or along the lateral side of the forearm dominated. 4. The proximal borders of the receptive fields were located close to joints. The area from which maximal responses were evoked was usually located eccentrically within the receptive field. Based on spatial characteristics the receptive fields could be divided into eight classes, which in turn were tentatively divided into subclasses. Similar subclasses of receptive fields were found in different cats. This classification was further supported by the results of a quantitative analysis of eighty-nine climbing fibres. The receptive fields of these climbing fibres were mapped with standardized noxious stimulation. 5. Climbing fibres terminating within sagittal strips (width, 100-300 microns; length, greater than 1 mm) had receptive fields which belonged to the same subclass. There were commonly abrupt changes in receptive fields between such microzones. Most classes of receptive fields were found in both the medial and the lateral parts of the C3 zone. However, receptive fields with a focus on the ventral side of either the metacarpals, the wrist or the forearm were found only in the medial part of the C3 zone. Furthermore, the class of receptive fields restricted to the lateral side of the upper arm and shoulder was only found in the lateral part of the C3 zone. 6. In the discussion, it is proposed that climbing fibres projecting to each microzone carry information from spinal multireceptive reflex arcs acting on a single muscle or a group of synergistic muscles.(ABSTRACT TRUNCATED AT 400 WORDS)