Higher-harmonic adaptation and the detection of squarewave gratings

Greenlee, Mark W.; Magnussen, Svein

doi:10.1016/0042-6989(87)90187-8

Cited by 10 publications

(4 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the two differ, psychophysical and electrophysiological thresholds rise, but at high test contrasts VEP amplitude is enhanced when adapted at high, and tested at low temporal frequencies. This is in agreement with all psychophysical threshold findings (Blakemore & Campbell, 1969;Greenlee & Magnussen, 1987;Greenlee & Heitger, 1988;Greenlee et al, 1991), with all VEP studies testing at low contrasts (Blakemore & Campbell, 1969;Mecacci & Spinelli, 1976;Manahilov & Vassilev, 1986;Suter et al, 1991), with all VEP studies where adapting and test frequency was identical (Ho & Berkley, 1988;Heinrich & Bach, 2001a), and with all VEP studies testing over a wide range of contrasts with differing adapting and test frequencies (Bach et al, 1988;Heinrich & Bach, 2001b). Further, this hypothesis fits well with findings by Georgeson (1985), where apparent contrast was not reduced when testing at contrasts higher than the adapting contrast, suggesting that contrast adaptation is not simply a shift of the contrast response function to higher contrast levels.…”

Section: Discussionsupporting

confidence: 85%

Contrast adaptation: Paradoxical effects when the temporal frequencies of adaptation and test differ

Heinrich¹,

Bach²

2002

Vis Neurosci

View full text Add to dashboard Cite

Previous studies of human contrast adaptation employing visually evoked potentials (VEP) have revealed contradictory results, namely, either a reduction or an enhancement in VEP amplitude. In a cross-adaptation experiment, we explored the possibility that differences in the temporal frequency of adapting and test patterns played a role. Phase-reversing checkerboard stimuli [1-deg check size, temporal frequency 8.5 or 17 reversals per second (rps)] served as adaptation and test pattern with contrasts of 0 or 97%. In 13 subjects, we recorded both retinal (PERG) and cortical (VEP) steady-state responses simultaneously. In a balanced block design, all four combinations of the temporal adaptation and test frequencies were employed. Contrast adaptation reduced the PERG amplitude by about 20% in every temporal condition (P < 0.001). The VEP amplitude was strongly affected by adaptation, but the effect differed in magnitude and sign depending on condition: With identical adaptation and test frequency, amplitude was reduced by 15% (P = 0.07) at 8.5 rps and by 38% at 17 rps (P < 0.05). Adapting at 8.5 rps and testing at 17 rps had a tiny (14%) insignificant effect, whereas adapting at 17 rps and testing at 8.5 rps revealed an amplitude enhancement of 27% (P < 0.05). These strong temporal cross-adaptation effects (in the VEP, but not in the PERG) suggest that the adaptable cortical mechanisms (gain control) can be narrowly tuned in their temporal properties. A sizable adaptation effect can even change its sign when varying the temporal frequency by a factor of two. This finding resolves contradictions between previous VEP adaptation studies and reconciles them with psychophysical findings.

show abstract

Section: Discussionsupporting

confidence: 85%

Contrast adaptation: Paradoxical effects when the temporal frequencies of adaptation and test differ

Heinrich¹,

Bach²

2002

Vis Neurosci

View full text Add to dashboard Cite

show abstract

“… Magnussen and Kurtenbach (1980) demonstrated that adding a second oriented adapting pattern decreased the TAE on the subsequent target, suggesting a inhibitory lateral interaction between the two patterns (see also Greenlee & Magnussen, 1987 , 1988 ). In the current study, we investigated the cross-orientation interaction in center-surround oriented gratings by manipulating the orientation of the adapter center and surround and observed its effects on the TAE.…”

Section: Discussionmentioning

confidence: 89%

“…The authors concluded that a lateral inhibition process was involved because the inhibitory effect from neurons inhibiting the vertical (and near vertical) orientation channels caused by the first adapter was inhibited by the second adapter (see also Kurtenbach & Magnussen, 1981 ). Similarly, Greenlee and Magnussen (1987 , 1988 ) implemented a method of sequential adaptation in which two adapting patterns were alternating in time during the adaptation phase and estimated the contrast threshold of a following target grating. Their results showed that, when the two adapting gratings were of the same spatial frequency or orientation, the target threshold increased, suggesting a suppressive effect.…”

Section: Introductionmentioning

confidence: 99%

The role of lateral modulation in orientation-specific adaptation effect

2022

Self Cite

View full text Add to dashboard Cite

Center-surround modulation in visual processing reflects a normalization process of contrast gain control in the responsive neurons. Prior adaptation to a clockwise (CW) tilted grating, for example, leads to the percept of counterclockwise tilt in a vertical grating, referred to as the tilt-aftereffect (TAE). We previously reported that the magnitude of the TAE is modulated by adding a same-orientation annular surround to an adapter, suggesting inhibitory lateral modulation. To further examine the property of this lateral modulation effect on the perception of a central target, we here used center-surround sinusoidal patterns as adapters and varied the adapter surround and center orientations independently. The target had the same spatial extent as the adapter center with no physical overlap with the adapter surround. Participants were asked to judge the target orientation as tilted either CW or counterclockwise from vertical after adaptation. Results showed that, when the surround orientation was held constant, the TAE magnitude was determined by the adapter center, peaking between 10° and 20° of tilt. More important, the adapter surround orientation modulated the adaptation effect such that the TAE magnitude first decreased and then increased as the surround orientation became increasingly more different from that of the center, suggesting that the surround modulation effect was indeed orientation specific. Our data can be accounted for by a divisive inhibition model, in which (1) the adaptation effect is represented by increasing the normalizing constant and (2) the surround modulation is captured by two multiplicative sensitivity parameters determined by the adapter surround orientation.

show abstract

“…they showed the visual system to perform contrast gradient analysis over a field width of typically 0.5°. Greenlee and Magnussen (1987) investigated the deteetion of low spatial square wave gratings by measuring the contrast threshold for a 0.33 cpd square wave grating after adaptation to high contrast sine gratings (1 and 3 cpd; not affecting the threshold for the 0.33 cpd square wave grating) and an 0.33 cpd square wave missing its fundamental frequency (increasing the threshold). The latter result is in accordance with the finding of Campbell ('/ al.…”

Section: Introductionmentioning

confidence: 99%