scholarly journals Attention operates uniformly throughout the classical receptive field and the surround

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Bram-Ernst Verhoef ◽  
John HR Maunsell

Shifting attention among visual stimuli at different locations modulates neuronal responses in heterogeneous ways, depending on where those stimuli lie within the receptive fields of neurons. Yet how attention interacts with the receptive-field structure of cortical neurons remains unclear. We measured neuronal responses in area V4 while monkeys shifted their attention among stimuli placed in different locations within and around neuronal receptive fields. We found that attention interacts uniformly with the spatially-varying excitation and suppression associated with the receptive field. This interaction explained the large variability in attention modulation across neurons, and a non-additive relationship among stimulus selectivity, stimulus-induced suppression and attention modulation that has not been previously described. A spatially-tuned normalization model precisely accounted for all observed attention modulations and for the spatial summation properties of neurons. These results provide a unified account of spatial summation and attention-related modulation across both the classical receptive field and the surround.

1993 ◽  
Vol 10 (4) ◽  
pp. 765-779 ◽  
Author(s):  
Michael H. Rowe ◽  
James F. Cox

AbstractWe have used frequency-domain methods to characterize the spatial receptive-field structure of cat retinal W cells. For most ON- and OFF-center tonic and phasic W cells, measurements of responsivity to drifting gratings at various spatial frequencies could be adequately described by a difference-of-Gaussians (DOG) function, consistent with the presence of center and surround mechanisms that are approximately Gaussian in shape and whose signals are combined additively. Estimates of the responsivity of the center mechanisms of tonic and phasic W cells were similar, but both were significantly lower than the corresponding values for X or Y cells. The width of the center mechanisms of tonic W cells, phasic W cells, and Y cells did not differ significantly from each other, but all were significantly larger than the width of X-cell centers. Surround parameters did not vary significantly among the four groups of ganglion cells. Measurements of contrast gain in both tonic and phasic W cells gave values that were significantly lower than in X or Y cells.Virtually all of the phasic W cells in our sample displayed evidence of spatial non-linearities in their receptive fields, in the form of either d.c. responses to drifting sine-wave gratings or second harmonic responses to counterphased gratings. The spatial resolution of the mechanism underlying these nonlinearities was typically higher than that of the center mechanism of these cells. Most tonic W cells exhibited linear spatial summation, although a subset gave strong second harmonic responses to counterphased gratings.Spatial-responsivity measurements for most ON-OFF and directionally selective W cells were not adequately described by DOG functions. These cells did, however, show evidence of spatial nonlinearities similar to those seen in phasic W cells. Suppressed-by-contrast cells gave both modulated and unmodulated responses to drifting gratings which both appeared to involved rectification, but which differed from each other in both spatial resolution and contrast gain.These data confirm earlier reports that the receptive fields of tonic and most ON- or OFF-center phasic W cells appear to include classical center and surround mechanisms. However, the receptive fields of some phasic cells, as well as ON-OFF and directionally selective W cells may have quite different structures. Our results also suggest that phasic, ON-OFF, directionally selective, suppressed-by-contrast, and a subset of tonic W cells may all receive nonlinear inputs with characteristics similar to those described in the receptive fields of retinal Y cells. If so, this has important implications for identifying and understanding the presynaptic circuitry of W cells, as well as the nature of their output to both telencephalic and midbrain visual targets.


1994 ◽  
Vol 11 (4) ◽  
pp. 703-720 ◽  
Author(s):  
Ming Sun ◽  
A. B. Bonds

AbstractThe two-dimensional organization of receptive fields (RFs) of 44 cells in the cat visual cortex and four cells from the cat LGN was measured by stimulation with either dots or bars of light. The light bars were presented in different positions and orientations centered on the RFs. The RFs found were arbitrarily divided into four general types: Punctate, resembling DOG filters (11%); those resembling Gabor filters (9%); elongate (36%); and multipeaked-type (44%). Elongate RFs, usually found in simple cells, could show more than one excitatory band or bifurcation of excitatory regions. Although regions inhibitory to a given stimulus transition (e.g. ON) often coincided with regions excitatory to the opposite transition (e.g. OFF), this was by no means the rule. Measurements were highly repeatable and stable over periods of at least 1 h. A comparison between measurements made with dots and with bars showed reasonable matches in about 40% of the cases. In general, bar-based measurements revealed larger RFs with more structure, especially with respect to inhibitory regions. Inactivation of lower cortical layers (V-VI) by local GABA injection was found to reduce sharpness of detail and to increase both receptive-field size and noise in upper layer cells, suggesting vertically organized RF mechanisms. Across the population, some cells bore close resemblance to theoretically proposed filters, while others had a complexity that was clearly not generalizable, to the extent that they seemed more suited to detection of specific structures. We would speculate that the broadly varying forms of cat cortical receptive fields result from developmental processes akin to those that form ocular-dominance columns, but on a smaller scale.


2008 ◽  
Vol 100 (2) ◽  
pp. 646-656 ◽  
Author(s):  
Ben Scholl ◽  
Michael Wehr

Sensory deafferentation results in rapid shifts in the receptive fields of cortical neurons, but the synaptic mechanisms underlying these changes remain unknown. The rapidity of these shifts has led to the suggestion that subthreshold inputs may be unmasked by a selective loss of inhibition. To study this, we used in vivo whole cell recordings to directly measure tone-evoked excitatory and inhibitory synaptic inputs in auditory cortical neurons before and after acoustic trauma. Here we report that acute acoustic trauma disrupted the balance of excitation and inhibition by selectively increasing and reducing the strength of inhibition at different positions within the receptive field. Inhibition was abolished for frequencies far below the trauma-tone frequency but was markedly enhanced near the edges of the region of elevated peripheral threshold. These changes occurred for relatively high-level tones. These changes in inhibition led to an expansion of receptive fields but not by a simple unmasking process. Rather, membrane potential responses were delayed and prolonged throughout the receptive field by distinct interactions between synaptic excitation and inhibition. Far below the trauma-tone frequency, decreased inhibition combined with prolonged excitation led to increased responses. Near the edges of the region of elevated peripheral threshold, increased inhibition served to delay rather than abolish responses, which were driven by prolonged excitation. These results show that the rapid receptive field shifts caused by acoustic trauma are caused by distinct mechanisms at different positions within the receptive field, which depend on differential disruption of excitation and inhibition.


1983 ◽  
Vol 50 (6) ◽  
pp. 1479-1496 ◽  
Author(s):  
D. R. Kenshalo ◽  
O. Isensee

Recordings were made from single SI cortical neurons in the anesthetized macaque monkey. Each isolated cortical neuron was tested for responses to a standard series of mechanical stimuli. The stimuli included brushing the skin, pressure, and pinch. The majority of cortical neurons responded with the greatest discharge frequency to brushing the receptive field, but neurons were found in areas 3b and 1 that responded maximally to pinching the receptive field. A total of 68 cortical nociceptive neurons were examined in 10 animals. Cortical neurons that responded maximally to pinching the skin were also tested for responses to graded noxious heat pulses (from 35 to 43, 45, 47, and 50 degrees C). If the neuron failed to respond or only responded to 50 degrees C, the receptive field was also heated to temperatures of 53 and 55 degrees C. Fifty-six of the total population of nociceptive neurons were tested for responses to the complete series of noxious heat pulses: 46 (80%) exhibited a progressive increase in the discharge frequency as a function of stimulus intensity, and the spontaneous activity of two (4%) was inhibited. One population of cortical nociceptive neurons possessed restricted, contralateral receptive fields. These cells encoded the intensity of noxious mechanical and thermal stimulation. Sensitization of primary afferent nociceptors was reflected in the responses of SI cortical nociceptive neurons when the ascending series of noxious thermal stimulation was repeated. The population of cortical nociceptive neurons with restricted receptive fields exhibited no adaptation in the response during noxious heat pulses of 47 and 50 degrees C. At higher temperatures the response often continued to increase during the stimulus. The other population of cortical nociceptive neurons was found to have restricted, low-threshold receptive fields on the contralateral hindlimb and, in addition, could be activated only by intense pinching or noxious thermal stimuli delivered on any portion of the body. The stimulus-response functions obtained from noxious thermal stimulation of the contralateral hindlimb were not different from cortical nociceptive neurons with small receptive fields. However, nociceptive neurons with large receptive fields exhibited a consistent adaptation during a noxious heat pulse of 47 and 50 degrees C. Based on the response characteristics of these two populations of cortical nociceptive neurons, we conclude that neurons with small receptive fields possess the ability to provide information about the localization, the intensity, and the temporal attributes of a noxious stimulus.4+.


1997 ◽  
Vol 78 (1) ◽  
pp. 366-382 ◽  
Author(s):  
Earl L. Smith ◽  
Yuzo Chino ◽  
Jinren Ni ◽  
Han Cheng

Smith, Earl L., III, Yuzo Chino, Jinren Ni, and Han Cheng. Binocular combination of contrast signals by striate cortical neurons in the monkey. J. Neurophysiol. 78: 366–382, 1997. With the use of microelectrode recording techniques, we investigated how the contrast signals from the two eyes are combined in individual cortical neurons in the striate cortex of anesthetized and paralyzed macaque monkeys. For a given neuron, the optimal spatial frequency, orientation, and direction of drift for sine wave grating stimuli were determined for each eye. The cell's disparity tuning characteristics were determined by measuring responses as a function of the relative interocular spatial phase of dichoptic stimuli that consisted of the optimal monocular gratings. Binocular contrast summation was then investigated by measuring contrast response functions for optimal dichoptic grating pairs that had left- to right-eye interocular contrast ratios that varied from 0.1 to 10. The goal was to determine the left- and right-eye contrast components required to produce a criterion threshold response. For all functional classes of cortical neurons and for both cooperative and antagonistic binocular interactions, there was a linear relationship between the left- and right-eye contrast components required to produce a threshold response. Thus, for example for cooperative binocular interactions, a reduction in contrast to one eye was counterbalanced by an equivalent increase in contrast to the other eye. These results showed that in simple cells and phase-specific complex cells, the contrast signals from the two eyes were linearly combined at the subunit level before nonlinear rectification. In non-phase-specific complex cells, the linear binocular convergence of contrast signals could have taken place either before or after the rectification process, but before spike generation. In addition, for simple cells, vector analysis of spatial summation showed that the inputs from the two eyes were also combined in a linear manner before nonlinear spike-generating mechanisms. Thus simple cells showed linear spatial summation not only within and between subregions in a given receptive field, but also between the left- and right-eye receptive fields. Overall, the results show that the effectiveness of a stimulus in producing a response reflects interocular differences in the relative balance of inputs to a given cell, however, the eye of origin of a light-evoked signal has no specific consequence.


1988 ◽  
Vol 59 (4) ◽  
pp. 1253-1276 ◽  
Author(s):  
R. Metherate ◽  
N. Tremblay ◽  
R. W. Dykes

1. Two-hundred and seven neurons were examined for changes in their responsiveness during the iontophoretic administration of acetylcholine (ACh) in barbiturate-anesthetized cats. 2. The laminar locations of 78 cells were determined. Cholinoceptive neurons were found in all cortical layers and ranged from 50% of the cells tested in layer I to 78% in layer VI. 3. When the responsiveness of a neuron was measured by the magnitude of the discharge generated by a fixed dose of glutamate, 30 of 47 cases (64%) were potentiated, and 4 (8%) were depressed when ACh was administered during glutamate-induced excitation. 4. ACh administered during glutamate excitation was significantly more effective in altering neuronal responsiveness than was ACh administered alone (P less than 0.001). 5. When the responsiveness of a neuron was measured by the magnitude of the discharge generated by a standard somatic stimulus applied to the receptive field, 42 of 52 cases (81%) were potentiated during ACh application. This was again different from ACh treatment alone where only 4 of 27 tests (15%) resulted in subsequent enhancement of the response to somatic stimuli. 6. ACh generally increased the responsiveness of neurons with peripheral receptive fields and caused the appearance of a receptive field in some cells lacking one. 7. In many cases the changes in excitability, as measured by responses either to glutamate or to somatic stimulation, remained for prolonged time periods. When glutamate was used to test excitability, 34% (16 of 47) of the enhancements lasted more than 5 min. When somatic stimuli were used 29% (15 of 52) lasted more than 5 min. With both measures some neurons still displayed enhanced responses more than 1 h after the treatment with ACh. 8. ACh appears to act as a permissive agent that allows modification of the effectiveness with which previously existing afferent inputs drive somatosensory cortical neurons. 9. This mechanism to alter neuronal responsiveness has many of the characteristics necessary to account for the reorganization observed in somatosensory cortex following alterations in its afferent drive and may be related to some forms of learning and memory.


2006 ◽  
Vol 18 (4) ◽  
pp. 562-579 ◽  
Author(s):  
Ko Sakai ◽  
Haruka Nishimura

Contextual modulation reported in early- to intermediate-level visual areas could be an essential component to signal border ownership (BO) that specifies the direction of figure along a contour. The surrounding regions that evoke significant suppression or facilitation are highly localized and asymmetric with respect to the center of the classical receptive field (CRF). We propose a hypothesis that such surrounding modulation is a basis for BO-selectivity. Although this idea has been discussed for several years, it is uncertain how many of a vast variety of surrounding organizations could signal correctly the direction of ownership, and how many could signal consistently for various stimuli. We carried out computationally a population study of the surrounding effects to investigate how many cells exhibit effective and consistent BO signals. We tested hundreds of various organizations, and found that most of the asymmetric, iso-orientation suppressive regions, regardless of position or size, lead to surprisingly high consistency in the direction of ownership for various stimuli. The combinations of iso-orientation suppression and cross-orientation facilitation indicate both high robustness and consistency in the ownership determination. We constructed a model for BO-selective neurons based on the surrounding effects, and investigated whether the model reproduces major characteristics of the neuronal responses, including a variety in the BO selectivity among neurons, consistency with respect to various stimuli, invariance to stimulus size, and co-selectivity to BO and contrast. The model reproduced successfully the major characteristics of BO-selective neurons.


2021 ◽  
Author(s):  
Giordano Ramos-Traslosheros ◽  
Marion Silies

In Drosophila, direction-selective neurons implement a mechanism of motion computation similar to cortical neurons, using contrast-opponent receptive fields with ON and OFF subunits. It is not clear how the presynaptic circuitry of direction-selective neurons in the OFF pathway supports this computation, because all major inputs are OFF-rectified neurons. Here, we reveal the biological substrate for motion computation in the OFF pathway. Three interneurons, Tm2, Tm9 and CT1, also provide information about ON stimuli to the OFF direction-selective neuron T5 across its receptive field, supporting a contrast-opponent receptive field organization. Consistent with its prominent role in motion detection, variability in Tm9 receptive field properties is passed on to T5, and calcium decrements in Tm9 in response to ON stimuli are maintained across behavioral states, while spatial tuning is sharpened by active behavior. Together, our work shows how a key neuronal computation is implemented by its constituent neuronal circuit elements to ensure direction selectivity.


2018 ◽  
Author(s):  
Ricardo Kienitz ◽  
Joscha T. Schmiedt ◽  
Katharine A. Shapcott ◽  
Kleopatra Kouroupaki ◽  
Richard C. Saunders ◽  
...  

SummaryGrowing evidence suggests that distributed spatial attention may invoke theta (3-9 Hz) rhythmic sampling processes. The neuronal basis of such attentional sampling is however not fully understood. Here we show using array recordings in visual cortical area V4 of two awake macaques that presenting separate visual stimuli to the excitatory center and suppressive surround of neuronal receptive fields elicits rhythmic multi-unit activity (MUA) at 3-6 Hz. This neuronal rhythm did not depend on small fixational eye movements. In the context of a distributed spatial attention task, during which the monkeys detected a spatially and temporally uncertain target, reaction times (RT) exhibited similar rhythmic fluctuations. RTs were fast or slow depending on the target occurrence during high or low MUA, resulting in rhythmic MUA-RT cross-correlations at at theta frequencies. These findings suggest that theta-rhythmic neuronal activity arises from competitive receptive field interactions and that this rhythm may subserve attentional sampling.HighlightsCenter-surround interactions induce theta-rhythmic MUA of visual cortex neuronsThe MUA rhythm does not depend on small fixational eye movementsReaction time fluctuations lock to the neuronal rhythm under distributed attention


2001 ◽  
Vol 18 (6) ◽  
pp. 973-981 ◽  
Author(s):  
L.E. MAHON ◽  
R.L. DE VALOIS

Cell responses to drifting Cartesian (parallel) and non-Cartesian (concentric, radial, and hyperbolic) stimuli were recorded in and beyond the classical receptive field (CRF) in the lateral geniculate nucleus (LGN), V1, and V2 of anesthetized monkeys. Many cells were equally responsive to Cartesian and non-Cartesian, especially concentric, gratings. Around 15% of cells in each area were significantly more responsive to concentric compared to parallel gratings; however, cells significantly more responsive to parallel compared to concentric gratings were more numerous in the cortex. While many cells responded to hyperbolic and radial gratings, few were most responsive to these gratings. Cell selectivity decreased for Cartesian and increased for non-Cartesian gratings from V1 to V2 and the relative response varied as a function of stimulus extent with respect to the CRF. Complex, nonoriented, nondirectional cells with a low aspect ratio (AR) responded best to non-Cartesian gratings. These results cannot be fully explained using Gabor linear/energy models of simple and complex receptive fields (RFs) although such models predict some cells to respond equally to Cartesian and non-Cartesian gratings. Cells significantly more responsive to non-Cartesian gratings can be accounted for by CRF selectivity influenced by modulation from the nonclassical receptive field (nCRF). The present study shows that Cartesian/non-Cartesian selectivity is not an emergent property of V4 cells but is present at all levels of early visual processing being subserved by a subset of cells with specific tuning properties.


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