scholarly journals Attentional Modulation of Visual Responses by Flexible Input Gain

2009 ◽  
Vol 101 (4) ◽  
pp. 2089-2106 ◽  
Author(s):  
Geoffrey M. Ghose
Keyword(s):  
Receptive Field ◽  
Spatial Attention ◽  
Sensory Integration ◽  
Suppressive Effect ◽  
Common Mechanism ◽  
Visual Responses ◽  
Attentional Modulation ◽  
Low Contrast ◽  
Imaging Results ◽  
Input Gain

Although it is clear that sensory responses in the cortex can be strongly modulated by stimuli outside of classical receptive fields as well as by extraretinal signals such as attention and anticipation, the exact rules governing the neuronal integration of sensory and behavioral signals remain unclear. For example, most experiments studying sensory interactions have not explored attention, while most studies of attention have relied on the responses to relatively limited sets of stimuli. However, a recent study of V4 responses, in which location, orientation, and spatial attention were systematically varied, suggests that attention can both facilitate and suppress specific sensory inputs to a neuron according to behavioral relevance. To explore the implications of such input gain, we modeled the effects of a center-surround organization of attentional modulation using existing receptive field models of sensory integration. The model is consistent with behavioral measurements of a suppressive effect that surrounds the facilitatory locus of spatial attention. When this center-surround modulation is incorporated into realistic models of sensory integration, it is able to explain seemingly disparate observations of attentional effects in the neurophysiological literature, including spatial shifts in receptive field position and the preferential modulation of low contrast stimuli. The model is also consistent with recent formulations of attention to features in which gain is variably applied among cells with different receptive field properties. Consistent with functional imaging results, the model predicts that spatial attention effects will vary between different visual areas and suggests that attention may act through a common mechanism of selective and flexible gain throughout the visual system.

Effects of attention and stimulus interaction on visual responses of inferior temporal neurons in macaque

1988 ◽  
Vol 60 (1) ◽  
pp. 344-364 ◽  
Author(s):  
T. Sato
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Discrimination Task ◽  
Temporal Cortex ◽  
Pattern Discrimination ◽  
Suppressive Effect ◽  
Neutral Stimulus ◽  
Inferior Temporal Cortex ◽  
Visual Response ◽  
Visual Responses

1. Extracellular discharges were recorded from neurons in the inferior temporal cortex (area TE) of three macaque monkeys while they performed visual fixation and pattern discrimination tasks. For the pattern discrimination task, monkey was trained to release the lever quickly at the onset of one of two pattern stimuli and to release the lever at the dimming of the other pattern. During this task, neutral light stimulus (light bar) to which the monkey was not required to respond was presented once a trial either prior to the onset of the discriminandum or during presentation of the pattern that dimmed later. The neuronal activities evoked by the neutral stimulus under these two conditions were compared. 2. When the discriminanda were located at the center or at 5 degrees in the contralateral visual field, one-half of the neurons showed significantly smaller responses to the neutral stimulus when it was presented during presentation of the dimming pattern than when it was presented prior to the onset of the discriminandum. 3. The suppressive effect depended on the location of the two stimuli. When the neutral stimulus was located in the ipsilateral visual field and the pattern was located in the contralateral visual field, the response to the neutral stimulus was suppressed. However, when the pattern was located in the ipsilateral visual field (5 degrees visual angle), still within the receptive field for many neurons, the suppressive effect of the pattern on the response to the neutral stimulus in the contralateral visual field was almost undetectable. 4. When the pattern was located nearer the fovea than was the neutral stimulus, the suppressive effect was greater than when the pattern was located more peripherally to the neutral stimulus. Different from the receptive field of more primary visual neurons, this suppressive effect did not appear to be related to the neuron's responsiveness to the patterns nor to precise stimulus location in the receptive field. 5. The magnitude of suppression by the attended pattern on the visual response during the pattern discrimination task correlated with the suppression noted in the presence of a fixation spot during the fixation tasks, while the animals did not fixate on the attended pattern. The response of some neurons to the neutral stimulus prior to pattern presentation during the pattern discrimination task was enhanced slightly compared with the response recorded during the simple fixation task.(ABSTRACT TRUNCATED AT 400 WORDS)

Nonlinear integration of multispectral information: Human colour vision analogues to sensory integration in rattlesnake

2012 ◽  
Vol 25 (0) ◽  
pp. 179
Author(s):  
Vincent A. Billock ◽  
Brian H. Tsou
Keyword(s):  
Spectral Sensitivity ◽  
Information Integration ◽  
Sensory Integration ◽  
Colour Vision ◽  
Neural Model ◽  
Neural Firing ◽  
Visual Responses ◽  
Neural Synchronization ◽  
Synchronization Mechanism ◽  
Integration Problems

Information integration occurs at every sensory scale and although distinctions are made for integration between and within senses, integration at intermediate scales may exploit familiar mechanisms. Here, we explore this idea by applying a sensory integration mechanism to some poorly understood multispectral integration problems in human colour vision. Billock and Tsou (IMRF, 2011) used a binding-like neural synchronization mechanism to model intensity-dependent (inverse) enhancement of visual responses by auditory stimulation in cat. The same model also applies to mutual enhancement of visual and infrared responses in rattlesnake, suggesting that a similar mechanism could model integration of spectral information in human colour vision. For example, chromatic brightness is thought to be a vector-like nonlinear combination of luminance and chromatic channels; its neural correlate is unknown. We model its spectral sensitivity by pairwise excitatory synchronization between luminance (broadband) neurons and cortically rectified L+M- and S+M-L- LGN neurons. Similarly, the yellow lobe of the yellow-blue opponent channel is known to be a nonlinearly enhanced combination of long- and medium-wavelength-sensitive inputs, but no sensible neural model for this interaction has been advanced. We model the spectral sensitivity of ‘yellowness’ using excitatory synchronization between cortically rectified L+M+S- and M+L- LGN units. The inputs for both simulations were macaque neural firing rate data (DeValois et al., 1966). Fascinatingly, in both cases, multispectral integration in human colour vision was well modeled using the rattlesnake/cat neural synchronization equations without any use of fitting parameters. This is the first application of sensory integration concepts to human colour vision transformations.

scholarly journals The Effect of Attention on Neuronal Responses to High and Low Contrast Stimuli

2010 ◽  
Vol 104 (2) ◽  
pp. 960-971 ◽  
Author(s):  
Joonyeol Lee ◽  
John H. R. Maunsell
Keyword(s):  
Cerebral Cortex ◽  
Visual Cortex ◽  
Rhesus Monkeys ◽  
Receptive Fields ◽  
Visual Area ◽  
Neuronal Responses ◽  
Attentional Modulation ◽  
Low Contrast ◽  
Middle Temporal ◽  
Visual Area Mt

It remains unclear how attention affects the tuning of individual neurons in visual cerebral cortex. Some observations suggest that attention preferentially enhances responses to low contrast stimuli, whereas others suggest that attention proportionally affects responses to all stimuli. Resolving how attention affects responses to different stimuli is essential for understanding the mechanism by which it acts. To explore the effects of attention on stimuli of different contrasts, we recorded from individual neurons in the middle temporal visual area (MT) of rhesus monkeys while shifting their attention between preferred and nonpreferred stimuli within their receptive fields. This configuration results in robust attentional modulation that makes it possible to readily distinguish whether attention acts preferentially on low contrast stimuli. We found no evidence for greater enhancement of low contrast stimuli. Instead, the strong attentional modulations were well explained by a model in which attention proportionally enhances responses to stimuli of all contrasts. These data, together with observations on the effects of attention on responses to other stimulus dimensions, suggest that the primary effect of attention in visual cortex may be to simply increase the strength of responses to all stimuli by the same proportion.

Response selectivity of neurons in area MT of the macaque monkey during reversible inactivation of area V1

1992 ◽  
Vol 67 (6) ◽  
pp. 1437-1446 ◽  
Author(s):  
P. Girard ◽  
P. A. Salin ◽  
J. Bullier
Keyword(s):  
Receptive Field ◽  
Macaque Monkey ◽  
Direction Selectivity ◽  
Area 17 ◽  
Visual Responses ◽  
Area Mt ◽  
Reversible Inactivation ◽  
Mt Neurons ◽  
Preferred Direction ◽  
Blocking Index

1. Behavioral results in the monkey and clinical studies in human show remarkable residual visual capacities after a lesion of area V1. Earlier work by Rodman et al. demonstrated that visual activity can be recorded in the middle temporal area (MT) of the macaque monkey several weeks after a complete lesion of V1. These authors also tested the effect of a reversible block of area V1 on the visual responses of a small number of neurons in area MT and showed that most of these cells remain visually responsive. From the results of that study, however, it is difficult to assess the contribution of area 17 to the receptive-field selectivity of area MT neurons. To address this question, we have quantitatively measured the effects of a reversible inactivation of area 17 on the direction selectivity of MT neurons. 2. A circular part of the opercular region of area V1 was reversibly inactivated by cooling with a Peltier device. A microelectrode was positioned in the lower layers of V1 to control the total inactivation of that area. Eighty percent of the sites recorded in the retinotopically corresponding region of MT during inactivation of V1 were found to be visually responsive. The importance of the effect was assessed by calculating the blocking index (0 for no effect, 1 for complete inactivation). Approximately one-half of the quantitatively studied neurons gave a blocking index below 0.6, illustrating the strong residual responses recorded in many neurons. 3. Receptive-field properties were examined with multihistograms. It was found that, during inactivation of V1, the preferred direction changed for most neurons but remained close to the preferred direction or to its opposite in the control situation. During inactivation of V1, the average tuning curve of neurons became broader mostly because of strong reductions in the response to directions close to the preferred and nonpreferred. Very little change was observed in the responses for directions at 90 degrees to the optimal. These results are consistent with a model in which direction selectivity is present without an input from V1 but is reinforced by the spatial organization of this excitatory input. 4. Residual responses were found to be highly dependent on the state of anesthesia because they were completely abolished by the addition of 0.4-0.5% halothane to the ventilation gases. Finally, visual responses were recorded in area MT several hours after an acute lesion of area 17.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Visual attention is available at a task-relevant location rapidly after a saccade

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Tao Yao ◽  
Madhura Ketkar ◽  
Stefan Treue ◽  
B Suresh Krishna
Keyword(s):  
Eye Movements ◽  
Spatial Attention ◽  
Spatial Location ◽  
Temporal Analysis ◽  
Neuronal Population ◽  
Attentional Modulation ◽  
Attention Task ◽  
Fine Grained ◽  
The One ◽  
Precise Time

Maintaining attention at a task-relevant spatial location while making eye-movements necessitates a rapid, saccade-synchronized shift of attentional modulation from the neuronal population representing the task-relevant location before the saccade to the one representing it after the saccade. Currently, the precise time at which spatial attention becomes fully allocated to the task-relevant location after the saccade remains unclear. Using a fine-grained temporal analysis of human peri-saccadic detection performance in an attention task, we show that spatial attention is fully available at the task-relevant location within 30 milliseconds after the saccade. Subjects tracked the attentional target veridically throughout our task: i.e. they almost never responded to non-target stimuli. Spatial attention and saccadic processing therefore co-ordinate well to ensure that relevant locations are attentionally enhanced soon after the beginning of each eye fixation.

scholarly journals Evidence for a common mechanism of spatial attention and visual awareness: Towards construct validity of pseudoneglect

PLoS ONE ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. e0212998 ◽  
Author(s):  
Jiaqing Chen ◽  
Jagjot Kaur ◽  
Hana Abbas ◽  
Ming Wu ◽  
Wenyi Luo ◽  
...  
Keyword(s):  
Construct Validity ◽  
Spatial Attention ◽  
Visual Awareness ◽  
Common Mechanism

Lateral geniculate neurons in behaving primates. I. Responses to two-dimensional stimuli

1991 ◽  
Vol 66 (3) ◽  
pp. 777-793 ◽  
Author(s):  
J. W. McClurkin ◽  
T. J. Gawne ◽  
B. J. Richmond ◽  
L. M. Optican ◽  
D. L. Robinson
Keyword(s):  
Receptive Field ◽  
Visual Information ◽  
Receptive Fields ◽  
Nonlinear Behavior ◽  
Temporal Patterns ◽  
Two Dimensional ◽  
Visual Responses ◽  
Linear Summation ◽  
Lateral Geniculate ◽  
Opposite Contrast

1. Using behaving monkeys, we studied the visual responses of single neurons in the parvocellular layers of the lateral geniculate nucleus (LGN) to a set of two-dimensional black and white patterns. We found that monkeys could be trained to make sufficiently reliable and stable fixations to enable us to plot and characterize the receptive fields of individual neurons. A qualitative examination of rasters and a statistical analysis of the data revealed that the responses of neurons were related to the stimuli. 2. The data from 5 of the 13 "X-like" neurons in our sample indicated the presence of antagonistic center and surround mechanisms and linear summation of luminance within center and surround mechanisms. We attribute the lack of evidence for surround antagonism in the eight neurons that failed to exhibit center-surround antagonism either to a mismatch between the size of the pixels in the stimuli and the size of the receptive field or to the lack of a surround mechanism (i.e., the type II neurons of Wiesel and Hubel). 3. The data from five other neurons confirm and extend previous reports indicating that the surround regions of X-like neurons can have nonlinearities. The responses of these neurons were not modulated when a contrast-reversing, bipartite stimulus was centered on the receptive field, which suggests a linear summation within the center and surround mechanisms. However, it was frequently the case for these neurons that stimuli of identical pattern but opposite contrast elicited responses of similar polarity, which indicates nonlinear behavior. 4. We found a wide variety of temporal patterns in the responses of individual LGN neurons, which included differences in the magnitude, width, and number of peaks of the initial on-transient and in the magnitude of the later sustained component. These different temporal patterns were repeatable and clearly different for different visual patterns. These results suggest that visual information may be carried in the shape as well as in the amplitude of the response waveform.

Corticogeniculate neurons, corticotectal neurons, and suspected interneurons in visual cortex of awake rabbits: receptive-field properties, axonal properties, and effects of EEG arousal

1987 ◽  
Vol 57 (4) ◽  
pp. 977-1001 ◽  
Author(s):  
H. A. Swadlow ◽  
T. G. Weyand
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Receptive Field ◽  
Receptive Fields ◽  
Spontaneous Firing ◽  
Visual Responses ◽  
Firing Rates ◽  
Axonal Conduction ◽  
Conduction Velocities ◽  
Stimulation Of

The intrinsic stability of the rabbit eye was exploited to enable receptive-field analysis of antidromically identified corticotectal (CT) neurons (n = 101) and corticogeniculate (CG) neurons (n = 124) in visual area I of awake rabbits. Eye position was monitored to within 1/5 degrees. We also studied the receptive-field properties of neurons synaptically activated via electrical stimulation of the dorsal lateral geniculate nucleus (LGNd). Whereas most CT neurons had either complex (59%) or motion/uniform (15%) receptive fields, we also found CT neurons with simple (9%) and concentric (4%) receptive fields. Most complex CT cells were broadly tuned to both stimulus orientation and velocity, but only 41% of these cells were directionally selective. We could elicit no visual responses from 6% of CT cells, and these cells had significantly lower conduction velocities than visually responsive CT cells. The median spontaneous firing rates for all classes of CT neurons were 4-8 spikes/s. CG neurons had primarily simple (60%) and concentric (9%) receptive fields, and none of these cells had complex receptive fields. CG simple cells were more narrowly tuned to both stimulus orientation and velocity than were complex CT cells, and most (85%) were directionally selective. Axonal conduction velocities of CG neurons (mean = 1.2 m/s) were much lower than those of CT neurons (mean = 6.4 m/s), and CG neurons that were visually unresponsive (23%) had lower axonal conduction velocities than did visually responsive CG neurons. Some visually unresponsive CG neurons (14%) responded with saccadic eye movements. The median spontaneous firing rates for all classes of CG neurons were less than 1 spike/s. All neurons synaptically activated via LGNd stimulation at latencies of less than 2.0 ms had receptive fields that were not orientation selective (89% motion/uniform, 11% concentric), whereas most cells with orientation-selective receptive fields had considerably longer synaptic latencies. Most short-latency motion/uniform neurons responded to electrical stimulation of the LGNd (and visual area II) with a high-frequency burst (500-900 Hz) of three or more spikes. Action potentials of these neurons were of short duration, thresholds of synaptic activation were low, and spontaneous firing rates were the highest seen in rabbit visual cortex. These properties are similar to those reported for interneurons in several regions in mammalian central nervous system. Nonvisual sensory stimuli that resulted in electroencephalographic arousal (hippocampal theta activity) had a profound effect on the visual responses of many visual cortical neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Attentional Recruitment of Inter-Areal Recurrent Networks for Selective Gain Control

2002 ◽  
Vol 14 (7) ◽  
pp. 1669-1689 ◽  
Author(s):  
Richard H. R. Hahnloser ◽  
Rodney J. Douglas ◽  
Klaus Hepp
Keyword(s):  
Receptive Field ◽  
Network Architecture ◽  
Receptive Fields ◽  
Sensory Information ◽  
Gain Control ◽  
External Noise ◽  
Stimulus Selection ◽  
Low Contrast ◽  
Winner Take All ◽  
Higher Visual Areas

There is strong anatomical and physiological evidence that neurons with large receptive fields located in higher visual areas are recurrently connected to neurons with smaller receptive fields in lower areas. We have previously described a minimal neuronal network architecture in which top-down attentional signals to large receptive field neurons can bias and selectively read out the bottom-up sensory information to small receptive field neurons (Hahnloser, Douglas, Mahowald, & Hepp, 1999). Here we study an enhanced model, where the role of attention is to recruit specific inter-areal feedback loops (e.g., drive neurons above firing threshold). We first illustrate the operation of recruitment on a simple example of visual stimulus selection. In the subsequent analysis, we find that attentional recruitment operates by dynamical modulation of signal amplification and response multistability. In particular, we find that attentional stimulus selection necessitates increased recruitment when the stimulus to be selected is of small contrast and of small distance away from distractor stimuli. The selectability of a low-contrast stimulus is dependent on the gain of attentional effects; for example, low-contrast stimuli can be selected only when attention enhances neural responses. However, the dependence of attentional selection on stimulus-distractor distance is not contingent on whether attention enhances or suppresses responses. The computational implications of attentional recruitment are that cortical circuits can behave as winner-take-all mechanisms of variable strength and can achieve close to optimal signal discrimination in the presence of external noise.

Sign in / Sign up

Export Citation Format

Share Document