scholarly journals Spatiotemporal dynamics of surround suppression in cat V1: Stimulus-size and orientation-contrast

2010 ◽  
Vol 6 (6) ◽  
pp. 891-891
Author(s):  
S. Shimegi ◽  
H. Kida ◽  
A. Ishikawa ◽  
H. Sato
Keyword(s):  
Spatiotemporal Dynamics ◽  
Stimulus Size ◽  
Surround Suppression ◽  
Orientation Contrast

Spatial Organization and Magnitude of Orientation Contrast Interactions in Primate V1

2002 ◽  
Vol 88 (5) ◽  
pp. 2796-2808 ◽  
Author(s):  
H. E. Jones ◽  
W. Wang ◽  
A. M. Sillito
Keyword(s):  
Spatial Organization ◽  
Image Features ◽  
Response Patterns ◽  
Surround Suppression ◽  
Contrast Effects ◽  
Specific Suppression ◽  
Orientation Contrast ◽  
Classical Receptive Field ◽  
Simple Variation ◽  
Different Response

We have explored the spatial organization of orientation contrast effects in primate V1. Our stimuli were either concentric patches of drifting grating of varying orientation and diameter or grating patches displaced in x–y coordinates around a central patch overlying the classical receptive field (CRF). All cells in the sample exhibited response suppression to iso-oriented stimuli exceeding the CRF. Changing the outer stimulus orientation revealed five response patterns: 1) orientation alignment suppression (17% of cells)—a suppressive component tuned to the same orientation as the cell's optimal, 2) orientation contrast facilitation (63%)—responses to orientation contrast stimuli exceeded those to the center stimulus alone, 3) nonorientation specific suppression (3%), 4) mixed general suppression and alignment suppression (14%), and 5) orientation contrast suppression (14%)—cross-oriented stimuli evoked stronger suppression than iso-oriented stimuli. Thus most cells (94%) showed larger responses to orientation contrast stimuli than to iso-oriented stimuli, and over one-half showed orientation contrast facilitation. There appeared to be a spatially structured organization of the zones driving the different response patterns with respect to the CRF. Nonorientation-specific suppression and orientation contrast suppression were predominantly evoked by orientation contrast borders located within the CRF, and orientation contrast facilitation was mainly driven by surround stimuli lying outside the CRF. This led to different response patterns according to border location. Zones driving orientation contrast facilitation were not necessarily contiguous to, nor uniformly distributed around, the CRF. Our data support two processes underlying orientation contrast enhancement effects: a simple variation in the strength of surround suppression drawing on the fact that surround suppression is tuned to the same orientation as the CRF and a second process driven by orientation contrast that enhanced cells' responses to CRF stimulation by either dis-inhibition or orientation contrast facilitation. We suggest these processes may serve to enhance response levels to salient image features such as junctions and corners and may contribute to orientation pop-out.

scholarly journals Spatiotemporal dynamics of surround suppression in cat V1: spatial-frequency dependency

2010 ◽  
Vol 6 (6) ◽  
pp. 892-892
Author(s):  
A. Ishikawa ◽  
S. Shimegi ◽  
H. Kida ◽  
H. Sato
Keyword(s):  
Spatial Frequency ◽  
Spatiotemporal Dynamics ◽  
Surround Suppression ◽  
Frequency Dependency

Evidence for a Stimulus Size-Response Position Correspondence Effect

2012 ◽  
Author(s):  
Barbara Treccani ◽  
Roberta Sellaro ◽  
Remo Job ◽  
Roberto Cubelli
Keyword(s):  
Stimulus Size ◽  
Response Position ◽  
Correspondence Effect

ASSESSMENT OF THE SPATIOTEMPORAL DYNAMICS OF THE MACROPHYTE THICKET ECOSYSTEMS IN THE NEVA BAY AND THE ADJACENT WATERS OF THE EASTERN GULF OF FINLAND

2017 ◽  
Author(s):  
Ekaterina Maksimova ◽  
Ekaterina Maksimova ◽  
Vladimir Zhigulsky ◽  
Vladimir Zhigulsky ◽  
Vladimir Shuisky ◽  
...  
Keyword(s):  
Aquatic Vegetation ◽  
Temporal Dynamics ◽  
Negative Impact ◽  
Spatiotemporal Dynamics ◽  
Gulf Of Finland ◽  
Active Growth ◽  
Nesting Sites ◽  
Significant Negative Impact ◽  
And Migration ◽  
Neva Bay

The macrophyte thicket ecosystems of higher aquatic vegetation in the Neva Bay (NB) and Eastern Gulf of Finland (EGoF) perform many important roles, including acting as the habitats, nesting sites and migration sites for aquatic and semi-aquatic birds, creating the specific conditions necessary for the spawning and growth of many species of fish, and taking part in the self-purification of the aquatic ecosystems. Many anthropogenic disturbances, hydraulic works in particular, have a significant negative impact on these macrophyte thicket ecosystems. In recent years, the active growth of a new type of macrophyte thicket has been observed in the NB. This is due to the aftereffects of the construction of the Saint Petersburg Flood Prevention Facility Complex (FPFC). It is quite likely that the total macrophyte thicket area in these waters is currently increasing. In the future, it will be necessary to assess the environmental impacts of the hydraulic works on the macrophyte thicket of the NB and EGoF, taking into account the background processes of the spatiotemporal dynamics of the reed beds in the waters in question. To do this, it will be necessary to carry out a comprehensive study of these ecosystems and identify patterns in their spatial and temporal dynamics. The program of the study has been developed and is currently being implemented by Eco-Express-Service, a St. Petersburg eco-design company.

Sign in / Sign up

Export Citation Format

Share Document