scholarly journals Precise visuotopic organization of the blind spot representation in primate V1

2015 ◽  
Vol 113 (10) ◽  
pp. 3588-3599 ◽  
Author(s):  
João C. B. Azzi ◽  
Ricardo Gattass ◽  
Bruss Lima ◽  
Juliana G. M. Soares ◽  
Mario Fiorani
Keyword(s):  
Neuronal Activity ◽  
Receptive Fields ◽  
Blind Spot ◽  
Mapping Method ◽  
Optic Disk ◽  
Topographic Map ◽  
Multiple Electrodes ◽  
Neuronal Mechanisms ◽  
Global Mapping ◽  
Direction Tuning

The optic disk is a region of the retina consisting mainly of ganglion cell axons and blood vessels, which generates a visual scotoma known as the blind spot (BS). Information present in the surroundings of the BS can be used to complete the missing information. However, the neuronal mechanisms underlying these perceptual phenomena are poorly understood. We investigate the topography of the BS representation (BSR) in cortical area V1 of the capuchin monkey, using single and multiple electrodes. Receptive fields (RFs) of neurons inside the BSR were investigated using two distinct automatic bias-free mapping methods. The first method (local mapping) consisted of randomly flashing small white squares. For the second mapping method (global mapping), we used a single long bar that moved in one of eight directions. The latter stimulus was capable of eliciting neuronal activity inside the BSR, possibly attributable to long-range surround activity taking place outside the borders of the BSR. Importantly, we found that the neuronal activity inside the BSR is organized topographically in a manner similar to that found in other portions of V1. On average, the RFs inside the BS were larger than those outside. However, no differences in orientation or direction tuning were found between the two regions. We propose that area V1 exhibits a continuous functional topographic map, which is not interrupted in the BSR, as expected by the distribution of photoreceptors in the retina. Thus V1 topography is better described as “visuotopic” rather than as a discontinuous “retinotopic” map.

Topographic map reorganization in cat area 17 after early monocular retinal lesions

2002 ◽  
Vol 19 (1) ◽  
pp. 85-96 ◽  
Author(s):  
KAZUKI MATSUURA ◽  
BIN ZHANG ◽  
TAKAFUMI MORI ◽  
EARL L. SMITH ◽  
JON H. KAAS ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Optic Disk ◽  
Area 17 ◽  
Topographic Map ◽  
Retinal Lesions ◽  
The World ◽  
Blind Spots ◽  
Made In

Neither discrete peripheral retinal lesions nor the normal optic disk produces obvious holes in one's percept of the world because the visual brain appears to perceptually “fill in” these blind spots. Where in the visual brain or how this filling in occurs is not well understood. A prevailing hypothesis states that topographic map of visual cortex reorganizes after retinal lesions, which “sews up” the hole in the topographic map representing the deprived area of cortex (cortical scotoma) and may lead to perceptual filling in. Since the map reorganization does not typically occur unless retinotopically matched lesions are made in both eyes, we investigated the conditions in which monocular retinal lesions can induce comparable map reorganization. We found that following monocular retinal lesions, deprived neurons in cat area 17 can acquire new receptive fields if the lesion occurred relatively early in life (8 weeks of age) and the lesioned cats experienced a substantial period of recovery (>3 years). Quantitative determination of the monocular and binocular response properties of reactivated units indicated that responses to the lesioned eye for such neurons were remarkably robust, and that the receptive-field properties for the two eyes were generally similar. Moreover, excitatory or inhibitory binocular interactions were found in the majority of experimental units when the two eyes were activated together. These results are consistent with the hypothesis that map reorganization after monocular retinal lesions require experience-dependent plasticity and may be involved in the perceptual filling in of blind spots due to retinal lesions early in life.

scholarly journals A predictive focus of gain modulation encodes target trajectories in insect vision

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Steven D Wiederman ◽  
Joseph M Fabian ◽  
James R Dunbier ◽  
David C O’Carroll
Keyword(s):  
Target Location ◽  
Insect Vision ◽  
Gain Modulation ◽  
Brain Hemispheres ◽  
Contrast Gain ◽  
Enhanced Sensitivity ◽  
Neuronal Mechanisms ◽  
New Locations ◽  
Direction Tuning ◽  
Predictive Processes

When a human catches a ball, they estimate future target location based on the current trajectory. How animals, small and large, encode such predictive processes at the single neuron level is unknown. Here we describe small target-selective neurons in predatory dragonflies that exhibit localized enhanced sensitivity for targets displaced to new locations just ahead of the prior path, with suppression elsewhere in the surround. This focused region of gain modulation is driven by predictive mechanisms, with the direction tuning shifting selectively to match the target’s prior path. It involves a large local increase in contrast gain which spreads forward after a delay (e.g. an occlusion) and can even transfer between brain hemispheres, predicting trajectories moved towards the visual midline from the other eye. The tractable nature of dragonflies for physiological experiments makes this a useful model for studying the neuronal mechanisms underlying the brain’s remarkable ability to anticipate moving stimuli.

Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. I. Receptive Fields and Discharge Patterns

1999 ◽  
Vol 81 (2) ◽  
pp. 825-834 ◽  
Author(s):  
Iran Salimi ◽  
Thomas Brochier ◽  
Allan M. Smith
Keyword(s):  
Receptive Field ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Single Cells ◽  
Precision Grip ◽  
Receptive Fields ◽  
Pressure Change ◽  
Discharge Pattern ◽  
Cortical Cells ◽  
Discharge Patterns

Neuronal activity in somatosensory cortex of monkeys using a precision grip. I. Receptive fields and discharge patterns. Three adolescent Macaca fascicularis monkeys weighing between 3.5 and 4 kg were trained to use a precision grip to grasp a metal tab mounted on a low friction vertical track and to lift and hold it in a 12- to 25-mm position window for 1 s. The surface texture of the metal tab in contact with the fingers and the weight of the object could be varied. The activity of 386 single cells with cutaneous receptive fields contacting the metal tab were recorded in Brodmann’s areas 3b, 1, 2, 5, and 7 of the somatosensory cortex. In this first of a series of papers, we describe three types of discharge pattern, the receptive-field properties, and the anatomic distribution of the neurons. The majority of the receptive fields were cutaneous and covered less than one digit, and a χ2 test did not reveal any significant differences in the Brodmann’s areas representing the thumb and index finger. Two broad categories of discharge pattern cells were identified. The first category, dynamic cells, showed a brief increase in activity beginning near grip onset, which quickly subsided despite continued pressure applied to the receptive field. Some of the dynamic neurons responded to both skin indentation and release. The second category, static cells, had higher activity during the stationary holding phase of the task. These static neurons demonstrated varying degrees of sensitivity to rates of pressure change on the skin. The percentage of dynamic versus static cells was about equal for areas 3b, 2, 5, and 7. Only area 1 had a higher proportion of dynamic cells (76%). A third category was identified that contained cells with significant pregrip activity and included cortical cells with both dynamic or static discharge patterns. Cells in this category showed activity increases before movement in the absence of receptive-field stimulation, suggesting that, in addition to peripheral cutaneous input, these cells also receive strong excitation from movement-related regions of the brain.

Alteration of Medullary Dorsal Horn Neuronal Activity Following Inferior Alveolar Nerve Transection in Rats

2001 ◽  
Vol 86 (6) ◽  
pp. 2868-2877 ◽  
Author(s):  
Koichi Iwata ◽  
Takao Imai ◽  
Yoshiyuki Tsuboi ◽  
Akimasa Tashiro ◽  
Akiko Ogawa ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Neuronal Activity ◽  
Dynamic Range ◽  
Escape Behavior ◽  
Receptive Fields ◽  
Inferior Alveolar Nerve ◽  
Skin Incision ◽  
Medullary Dorsal Horn ◽  
Whisker Pad ◽  
Wdr Neurons

The effects of inferior alveolar nerve (IAN) transection on escape behavior and MDH neuronal activity to noxious and nonnoxious stimulation of the face were precisely analyzed. Relative thresholds for escape from mechanical stimulation applied to the whisker pad area ipsilateral to the transection were significantly lower than that for the contralateral and sham-operated whisker pad until 28 days after the transection, then returned to the preoperative level at 40 days after transection. A total of 540 neurons were recorded from the medullary dorsal horn (MDH) of the nontreated naive rats [low-threshold mechanoreceptive (LTM), 27; wide dynamic range (WDR), 31; nociceptive specific (NS), 11] and sham-operated rats with skin incision (LTM, 34; WDR, 30; NS, 23) and from the ipsilateral (LTM, 82; WDR, 82; NS, 31) and contralateral MDH relative to the IAN transection (LTM, 77; WDR, 82; NS, 33). The electrophysiological properties of these neurons were precisely analyzed. Background activity of WDR neurons on the ipsilateral side relative to the transection was significantly increased at 2–14 days after the operation as compared with that of naive rats. Innocuous and noxious mechanical-evoked responses of LTM and WDR neurons were significantly enhanced at 2–14 days after IAN transection. The mean area of the receptive fields of WDR neurons was significantly larger on the ipsilateral MDH at 2–7 days after transection than that of naive rats. We could not observe any modulation of thermal responses of WDR and NS neurons following IAN transection. Also, no MDH neurons were significantly affected in the rats with sham operations. The present findings suggest that the increment of neuronal activity of WDR neurons in the MDH following IAN transection may play an important role in the development of the mechano-allodynia induced in the area adjacent to the area innervated by the injured nerve.

Lipopolysaccharide effects on neuronal activity in rat basal forebrain and hypothalamus during sleep and waking

2000 ◽  
Vol 278 (3) ◽  
pp. R620-R627
Author(s):  
Xinzheng Xi ◽  
Linda A. Toth
Keyword(s):  
Neuronal Activity ◽  
Basal Forebrain ◽  
Preoptic Area ◽  
Intraperitoneal Administration ◽  
Brain Regions ◽  
Neuronal Firing ◽  
Firing Patterns ◽  
Firing Rates ◽  
Neuronal Mechanisms ◽  
The Brain

Peripheral administration of lipopolysaccharide (LPS) is associated with alterations in sleep and the electroencephalogram. To evaluate potential neuronal mechanisms for the somnogenic effects of LPS administration, we used unanesthetized rats to survey the firing patterns of neurons in various regions of rat basal forebrain (BF) and hypothalamus during spontaneous sleep and waking and during the epochs of sleep and waking that occurred after the intraperitoneal administration of LPS. In the brain regions studied, LPS administration was associated with altered firing rates in 39% of the neurons examined. A larger proportion of LPS-responsive units showed vigilance-related alterations in firing rates compared with nonresponsive units. Approximately equal proportions of LPS-responsive neurons showed increased and decreased firing rates after LPS administration, with some units in the lateral preoptic area of the hypothalamus showing particularly robust increases. These findings are consistent with other studies showing vigilance-related changes in neuronal activity in various regions of BF and hypothalamus and further demonstrate that peripheral LPS administration alters neuronal firing rates in these structures during both sleep and waking.

The Adaptive Significance of the Location of the Optic Disk

Perception ◽  
1987 ◽  
Vol 16 (5) ◽  
pp. 649-654 ◽  
Author(s):  
Aries Arditi
Keyword(s):  
Visual Space ◽  
Spatial Arrangement ◽  
Blind Spot ◽  
Adaptive Significance ◽  
The Other ◽  
Optic Disk ◽  
Horizontal Position ◽  
Fixation Distance ◽  
Adaptive Property ◽  
Blind Spots

Although the ‘filling in’ of each blind spot by healthy retina in the other eye has long been described as an adaptive property of the spatial arrangement of the optic disks, an explanation of why the disks are specifically located where they are has yet to be proposed. A rationale for their horizontal position in humans is offered that is based on the projections of the blind spots in visual space in relation to fixation distance and to the protrusion of the bony facial occlusion of the nose bridge.

Computation of motion direction by quail retinal ganglion cells that have a nonconcentric receptive field

2000 ◽  
Vol 17 (2) ◽  
pp. 263-271 ◽  
Author(s):  
HIROYUKI UCHIYAMA ◽  
TAKAHIDE KANAYA ◽  
SHOICHI SONOHATA
Keyword(s):  
Receptive Field ◽  
Retinal Ganglion Cells ◽  
Japanese Quail ◽  
Ganglion Cells ◽  
Receptive Fields ◽  
Object Motion ◽  
Directional Selectivity ◽  
Retinal Ganglion ◽  
Motion Direction ◽  
Neuronal Mechanisms

One type of retinal ganglion cells prefers object motion in a particular direction. Neuronal mechanisms for the computation of motion direction are still unknown. We quantitatively mapped excitatory and inhibitory regions of receptive fields for directionally selective retinal ganglion cells in the Japanese quail, and found that the inhibitory regions are displaced about 1–3 deg toward the side where the null sweep starts, relative to the excitatory regions. Directional selectivity thus results from delayed transient suppression exerted by the nonconcentrically arranged inhibitory regions, and not by local directional inhibition as hypothesized by Barlow and Levick (1965).

Kernel-Based Equiprobabilistic Topographic Map Formation

1998 ◽  
Vol 10 (7) ◽  
pp. 1847-1871 ◽  
Author(s):  
Marc M. Van Hulle
Keyword(s):  
Density Estimation ◽  
Ad Hoc ◽  
Receptive Fields ◽  
Learning Rule ◽  
Basis Functions ◽  
Nonparametric Density Estimation ◽  
Topographic Map ◽  
Fixed Topology ◽  
Local Input ◽  
Learning Schemes

We introduce a new unsupervised competitive learning rule, the kernel-based maximum entropy learning rule (kMER), which performs equiprobabilistic topographic map formation in regular, fixed-topology lattices, for use with nonparametric density estimation as well as nonparametric regression analysis. The receptive fields of the formal neurons are overlapping radially symmetric kernels, compatible with radial basis functions (RBFs); but unlike other learning schemes, the radii of these kernels do not have to be chosen in an ad hoc manner: the radii are adapted to the local input density, together with the weight vectors that define the kernel centers, so as to produce maps of which the neurons have an equal probability to be active (equiprobabilistic maps). Both an “online” and a “batch” version of the learning rule are introduced, which are applied to nonparametric density estimation and regression, respectively. The application envisaged is blind source separation (BSS) from nonlinear, noisy mixtures.

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