scholarly journals Cortical magnification factor and population receptive field size in human V1 predict the bottom-up saliency map

2014 ◽  
Vol 14 (10) ◽  
pp. 537-537
Author(s):  
X. Zhang ◽  
F. Fang
Keyword(s):  
Receptive Field ◽  
Saliency Map ◽  
Field Size ◽  
Magnification Factor ◽  
Bottom Up ◽  
Receptive Field Size ◽  
Cortical Magnification ◽  
Cortical Magnification Factor

scholarly journals Radial asymmetries in population receptive field size and cortical magnification factor in early visual cortex

2017 ◽  
Vol 17 (10) ◽  
pp. 587
Author(s):  
Ben Harvey ◽  
Jan Brascamp ◽  
Sónia Ferreira ◽  
Miguel Castelo-Branco ◽  
Serge Dumoulin ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Field ◽  
Field Size ◽  
Magnification Factor ◽  
Receptive Field Size ◽  
Early Visual Cortex ◽  
Cortical Magnification ◽  
Cortical Magnification Factor

Radial asymmetries in population receptive field size and cortical magnification factor in early visual cortex

NeuroImage ◽  
2018 ◽  
Vol 167 ◽  
pp. 41-52 ◽  
Author(s):  
Maria Fatima Silva ◽  
Jan W. Brascamp ◽  
Sónia Ferreira ◽  
Miguel Castelo-Branco ◽  
Serge O. Dumoulin ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Field ◽  
Field Size ◽  
Magnification Factor ◽  
Receptive Field Size ◽  
Early Visual Cortex ◽  
Cortical Magnification ◽  
Cortical Magnification Factor

Dynamics and Formation of Self-Organizing Maps

1991 ◽  
Vol 3 (1) ◽  
pp. 54-66 ◽  
Author(s):  
Jun Zhang
Keyword(s):  
Transfer Functions ◽  
Mathematical Formulation ◽  
Field Size ◽  
Magnification Factor ◽  
Self Organizing Maps ◽  
Cortical Magnification ◽  
Binary Input ◽  
Cortical Magnification Factor ◽  
External Stimuli ◽  
Cortical Map

Amari (1983, 1989) proposed a mathematical formulation on the self-organization of synaptic efficacies and neural response fields under the influence of external stimuli. The dynamics as well as the equilibrium properties of the cortical map were obtained analytically for neurons with binary input-output transfer functions. Here we extend this approach to neurons with arbitrary sigmoidal transfer function. Under the assumption that both the intracortical connection and the stimulus-driven thalamic activity are well localized, we are able to derive expressions for the cortical magnification factor, the point-spread resolution, and the bandwidth resolution of the map. As a highlight, we show analytically that the receptive field size of a cortical neuron in the map is inversely proportional to the cortical magnification factor at that map location, the experimentally well-established rule of inverse magnification in retinotopic and somatotopic maps.

Receptive Field Size and Response Latency Are Correlated Within the Cat Visual Thalamus

2005 ◽  
Vol 93 (6) ◽  
pp. 3537-3547 ◽  
Author(s):  
Chong Weng ◽  
Chun-I Yeh ◽  
Carl R. Stoelzel ◽  
Jose-Manuel Alonso
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Response Latency ◽  
Time Course ◽  
Frequency Tuning ◽  
Receptive Fields ◽  
Cortical Cell ◽  
Field Size ◽  
Receptive Field Size ◽  
Spatial Frequency Tuning

Each point in visual space is encoded at the level of the thalamus by a group of neighboring cells with overlapping receptive fields. Here we show that the receptive fields of these cells differ in size and response latency but not at random. We have found that in the cat lateral geniculate nucleus (LGN) the receptive field size and response latency of neighboring neurons are significantly correlated: the larger the receptive field, the faster the response to visual stimuli. This correlation is widespread in LGN. It is found in groups of cells belonging to the same type (e.g., Y cells), and of different types (i.e., X and Y), within a specific layer or across different layers. These results indicate that the inputs from the multiple geniculate afferents that converge onto a cortical cell (approximately 30) are likely to arrive in a sequence determined by the receptive field size of the geniculate afferents. Recent studies have shown that the peak of the spatial frequency tuning of a cortical cell shifts toward higher frequencies as the response progresses in time. Our results are consistent with the idea that these shifts in spatial frequency tuning arise from differences in the response time course of the thalamic inputs.

Hebb-Type Dynamics is Sufficient to Account for the Inverse Magnification Rule in Cortical Somatotopy

1990 ◽  
Vol 2 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Kamil A. Grajski ◽  
Michael M. Merzenich
Keyword(s):  
Computer Simulation ◽  
Receptive Field ◽  
Cortical Neuron ◽  
Inverse Relationship ◽  
Unit Area ◽  
Skin Surface ◽  
Field Size ◽  
Synaptic Modification ◽  
Somatotopic Map ◽  
Cortical Magnification

The inverse magnification rule in cortical somatotopy is the experimentally derived inverse relationship between cortical magnification (area of somatotopic map representing a unit area of skin surface) and receptive field size (area of restricted skin surface driving a cortical neuron). We show by computer simulation of a simple, multilayer model that Hebb-type synaptic modification subject to competitive constraints is sufficient to account for the inverse magnification rule.

scholarly journals SUVOKIAMO ATKARPOS ILGIO PRIKLAUSOMYBĖ NUO JOS ATVAIZDO VIETOS AKIES TINKLAINĖJE

Psichologija ◽  
2011 ◽  
Vol 43 ◽  
pp. 78-91
Author(s):  
A. Dzekevičiūtė ◽  
A. Daugirdienė ◽  
A. Švegžda ◽  
R. Stanikūnas ◽  
H. Vaitkevičius
Keyword(s):  
Visual Field ◽  
Line Length ◽  
The Other ◽  
Size Perception ◽  
Normal Vision ◽  
Magnification Factor ◽  
Extremum Point ◽  
Cortical Magnification ◽  
Cortical Magnification Factor ◽  
The Given

Tyrimo tikslas yra patikrinti, kaip keičiasi objekto dydžio suvokimas, kintant jo projekcijos padėčiai akies tinklainėje, ir kaip objekto dydžio suvokimas priklauso nuo akies tinklainės receptorių (kūgelių ir lazdelių) tankio. Tiriamieji, žiūrėdami viena akimi ir fiksuodami žvilgsnį, dalijo skirtingų ilgių atkarpas – nustatydavo suvokiamą vidurį. Atkarpos dalių santykio nuo atkarpos ilgio funkcija turėjo lūžio tašką (66,7 proc. tiriamiesiems, kai atkarpos ilgis 7 laipsniai, 23,33 proc. – 13 laipsnių, kiti neturėjo). Rezultatai aiškinami skirtingu kūgelių ir lazdelių tankiu akies tinklainėje ir skirtinga kūgelių ir lazdelių įtaka.Pagrindiniai žodžiai: dydžio suvokimas, žievinis didinimo veiksnys, fotoreceptorių tankis.Perceived Size of a Line Depending on Its Projection Place on the RetinaDzekevičiūtė A., Daugirdienė A., Švegžda A., Stanikūnas R., Vaitkevičius H. SummaryIt is known that objects located in the centre of the visual field are perceived as larger than the objects located in the periphery (Пиаже, 1978). The image of an object differs from its perception object. The perceived size of an object depends on the size of its image in the visual cortex. This stems from the so-called cortical magnification factor. It is assumed that the same quantity of receptors sends information to the same area of the cortex. But photoreceptors are different – rods and the cones. It is not clear whether the different type of receptors make a different influence on the above-mentioned distortion of mapping. Also, the image of the object on the retina is perceived differently, depending on its location on the retina. Our goal was to explore how this subjective expansion changes while moving away from the centre of the retina, because there are no data on this, phenomenon.Method. Thirty normal or corrected to normal vision adults participated in the study. Five different length lines (5, 7, 10, 13, 15 degrees) were represented on the computer’s monitor one line at a time. Participants had monoculary bisected lines into two subjectively equal parts fixating sight on a cross located at the given end of the line.Results. The ratio ρ (length of the line near the cross / length of the other part) was calculated. This ratio as a function of the length of the whole line was not monotonic: when the line was short, ρ decreased, but then it began to increase. Three groups of results were formed considering the ratio of the line length (where the function had the extremum point). The largest group (66.67%) had the extremum point when the line length was 7 deg. The second group (23.33%) had the extremum point when the line length was 13 deg. The last group (10%) had not clear extremum point and was excluded from the calculation. Changes of the ρ value cannot be explained by the perceptual instability of the length of the line (Brown, 1953). There could be a correlation between the value of ρ and the density of all receptors in the retina where the line was projected.Conclusions. Humans make a bias while monocular by bisecting a line: the part near the point of fixation is perceived as bigger than the other part. The function of the line size ratio changes not monotonically – it has an extremum point. Most often, the extremum point is observed when the line size is 7 deg. This point is near the point where the density of rods exceeds that of cones. Other subjects show the extremum point when line size is 13 deg., but the reasons for such a point shift remain unclear. Some subjects have no extremum point.Key words: size perception, cortical magnification factor, density of photoreceptors.

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