Responses of monkey inferior temporal neurons to luminance-, motion-, and texture-defined gratings

1995 ◽  
Vol 73 (4) ◽  
pp. 1341-1354 ◽  
Author(s):  
G. Sary ◽  
R. Vogels ◽  
G. Kovacs ◽  
G. A. Orban
Keyword(s):  
Visual Perception ◽  
Relative Motion ◽  
Discrimination Task ◽  
Stimulus Presentation ◽  
Response Strength ◽  
The Other ◽  
Orientation Discrimination ◽  
Macaque Monkeys ◽  
Tuning Width ◽  
Visual Cortical

1. We recorded from neurons responsive to gratings in the inferior temporal (IT) cortices of macaque monkeys. One of the monkeys performed an orientation discrimination task; the other maintained fixation during stimulus presentation. Stimuli consisted of gratings based on discontinuities in luminance, relative motion, and texture. 2. IT cells responded well to gratings defined solely by relative motion, implying either direct or indirect motion input into IT, an area that is part of the ventral visual cortical pathway. 3. Response strength in general did not depend on the cue used to define the gratings. Latency values observed for the two static grating types (luminance- and texture-defined gratings) were similar, but significantly shorter than those measured for the kinetic gratings. 4. Stimulus orientation had a significant effect in 27%, 27%, and 9% of the cells tested with luminance-, kinetic-, and texture-defined gratings, respectively. 5. Only a small proportion of cells were orientation sensitive for more than one defining cue. The average preferred orientation for luminance and kinetic gratings matched; the tuning width was similar for the two cues. 6. Our results indicate that IT cells may contribute to cue-invariant coding of boundaries and edges. We discuss the relevance of these results to visual perception.

Enhancement of inferior temporal neurons during visual discrimination

1987 ◽  
Vol 58 (6) ◽  
pp. 1292-1306 ◽  
Author(s):  
B. J. Richmond ◽  
T. Sato
Keyword(s):  
Spatial Attention ◽  
Trial Type ◽  
Discrimination Task ◽  
Temporal Cortex ◽  
Pattern Discrimination ◽  
Response Strength ◽  
The Other ◽  
Inferior Temporal Cortex ◽  
Attention Task ◽  
Type Pattern

1. Previous results have shown that spatially directed attention enhances the stimulus-elicited responses of neurons in some areas of the brain. In the inferior temporal (IT) cortex, however, directing attention toward a stimulus mildly inhibits the responses of the neurons. Inferior temporal cortex is involved in pattern discrimination, but not spatial localization. If enhancement signifies that a neuron is participating in the function for which that part of cortex is responsible, then pattern discrimination, not spatial attention, should enhance responses of IT neurons. The influence of pattern discrimination behavior on the responses of IT neurons was therefore compared with previously reported suppressive influences of both spatial attention and the fixation point. 2. Single IT neurons were recorded from two monkeys while they performed each of five tasks. One task required the monkey to make a pattern discrimination between a bar and a square of light. In the other four tasks the same bar of light appeared, but the focus of spatial attention could differ, and the fixation point could be present or absent. Either attention to (without discrimination of) the bar stimulus or the presence of the fixation point attenuated responses slightly. These two suppressive influences produced a greater attenuation when both were present. 3. The visual conditions and motor requirements when the bar stimulus appeared in the discrimination task were identical to those of the trials in the stimulus attention task. However, one-half of the responsive neurons showed significantly stronger responses to the bar stimulus when it appeared in the discrimination task than when it appeared in the stimulus attention task. For most of these neurons, discrimination just overcame the combined effect of the two suppressive influences. For six other neurons, the response strength was significantly greater during the discrimination task than during any other task. 4. The monkeys achieved an overall correct performance rate of 90% in both the discrimination and stimulus attention tasks. To achieve this performance in the discrimination task they adopted a strategy in which they performed one trial type, bar stimulus attention trials, perfectly (100%) and the other trial type, pattern trials, relatively poorly (84% correct).(ABSTRACT TRUNCATED AT 400 WORDS)

The Effect of Feature Uncertainty on Spatial Discriminations

Perception ◽  
1988 ◽  
Vol 17 (5) ◽  
pp. 565-577 ◽  
Author(s):  
Rufin Vogels ◽  
Hilde Eeckhout ◽  
Guy A Orban
Keyword(s):  
Spatial Frequency ◽  
Discrimination Task ◽  
Processing Time ◽  
Stimulus Presentation ◽  
The Other ◽  
Stimulus Processing ◽  
Uncertainty Condition ◽  
The Subject ◽  
Stimulus Offset

Just noticeable differences (JNDs) in orientation and spatial frequency were measured under two conditions. In one condition the subject was cued before stimulus presentation as to the feature to be discriminated on that trial, while in the other condition the subject was cued only after stimulus offset. JNDs were larger in the latter, feature uncertainty, condition. This feature uncertainty effect increased with decreasing stimulus processing time. The results suggest that this feature uncertainty effect is of sensorial origin. They also demonstrate that it is possible for humans to address selectively those mechanisms that are most relevant for a given discrimination task.

Effects of Simultaneous and Successive Stimulus Presentation on Visual Discriminations by Aphasic Patients

1970 ◽  
Vol 13 (2) ◽  
pp. 369-381 ◽  
Author(s):  
Deedra L. Engmann ◽  
Robert H. Brookshire
Keyword(s):  
Discrimination Task ◽  
Stimulus Presentation ◽  
Simultaneous Presentation ◽  
Single Stimulus ◽  
Successive Discrimination ◽  
The Other ◽  
Successive Presentation ◽  
Gradual Improvement ◽  
Hospital Patients ◽  
Visual Discriminations

In order to determine whether aphasic and nonaphasic subjects would perform differentially in simultaneous and successive discrimination tasks, 10 aphasic and 10 nonaphasic hospital patients performed in a successive and a simultaneous discrimination task in which 2 stimuli were presented on each trial, and in a successive discrimination with a single stimulus presented on each trial. Aphasic and nonaphasic subjects learned the successive discrimination task with a single stimulus faster than the other two discriminations. When the discrimination involved two stimuli, simultaneous presentation of stimuli resulted in faster learning by aphasic subjects than did successive presentation. Learning of visual discriminations by aphasic and nonaphasic subjects appeared to occur all at once, rather than as gradual improvement over trials. The hypothesis that aphasic subjects would have difficulty with inhibition of responses to negative discriminative stimuli was not supported.

scholarly journals A Role of Amygdala in Visual Perception and Cognition in Macaque Monkeys (Macaca fuscata and Macaca mulatta)

1990 ◽  
Vol 161 (Supplement) ◽  
pp. 95-120 ◽  
Author(s):  
EIICHI IWAI ◽  
MASAO YUKIE ◽  
JOJI WATANABE ◽  
KAZUO HIKOSAKA ◽  
HIDEO SUYAMA ◽  
...  
Keyword(s):  
Visual Perception ◽  
Macaca Mulatta ◽  
Macaca Fuscata ◽  
Macaque Monkeys

Auditory Temporal Order Perception in Younger and Older Adults

1998 ◽  
Vol 41 (5) ◽  
pp. 1052-1060 ◽  
Author(s):  
Peter J. Fitzgibbons ◽  
Sandra Gordon-Salant
Keyword(s):  
Older Adults ◽  
Temporal Processing ◽  
Discrimination Task ◽  
Temporal Order ◽  
Stimulus Presentation ◽  
Complex Stimulus ◽  
Frequency Range ◽  
Identification Task ◽  
Relative Pitch ◽  
Single Sequence

This investigation examined the abilities of younger and older listeners to discriminate and identify temporal order of sounds presented in tonal sequences. It was hypothesized that older listeners would exhibit greater difficulty than younger listeners on both temporal processing tasks, particularly for complex stimulus patterns. It was also anticipated that tone order discrimination would be easier than tone order identification for all listeners. Listeners were younger and older adults with either normal hearing or mild-to-moderate sensorineural hearing losses. Stimuli were temporally contiguous three-tone sequences within a 1/3 octave frequency range centered at 4000 Hz. For the discrimination task, listeners discerned differences between standard and comparison stimulus sequences that varied in tonal temporal order. For the identification task, listeners identified tone order of a single sequence using labels of relative pitch. Older listeners performed more poorly than younger listeners on the discrimination task for the more complex pitch patterns and on the identification task for faster stimulus presentation rates. The results also showed that order discrimination is easier than order identification for all listeners. The effects of hearing loss on the ordering tasks were minimal.

Deficits in Complex Visual Perception Following Unilateral Temporal Lobectomy

1998 ◽  
Vol 10 (3) ◽  
pp. 395-407 ◽  
Author(s):  
Krystel R. Huxlin ◽  
William H. Merigan
Keyword(s):  
Visual Field ◽  
Visual Perception ◽  
Temporal Cortex ◽  
Stimulus Presentation ◽  
Texture Segmentation ◽  
Temporal Lobectomy ◽  
Long Term Memory ◽  
Additional Control ◽  
Short And Long Term ◽  
Visual Discriminations

Although human temporal cortex is known to be important for short- and long-term memory, its role in visual perception is not well understood. In this study, we compared the performance of three patients with unilateral temporal lobectomies to that of normal controls on both fisimplefl and ficomplexfl visual discriminations that did not involve explicit memory components. Two types of complex tasks were tested that involved discriminations secondary to texture segmentation. These were contrasted with simple discriminations using luminance-defined stimuli. Patients showed impaired thresholds only on tasks involving texture segmentation, performing as well as controls when the targets were defined by luminance rather than texture. The minimum stimulus presentation times for threshold performance were also measured for all tasks and found to be elevated in temporal lobectomy patients relative to controls. Although the magnitude of the deficits observed was substantial, loss was equivalent in ipsi- and contra-lesional regions of the visual field. Additional control experiments showed that the patients' perceptual deficits were not due, even in part, to disturbances of basic visual capacities such as acuity and contrast sensitivity. Our results indicate that temporal lobe damage disrupts complex, but not simple, visual discriminations throughout the visual field.

Experimental Studies on the Uncomfortable Loudness Level

1971 ◽  
Vol 14 (2) ◽  
pp. 262-270 ◽  
Author(s):  
S. D. G. Stephens ◽  
C. M. B. Anderson
Keyword(s):  
Test Anxiety ◽  
Free Field ◽  
Experimental Studies ◽  
Stimulus Presentation ◽  
Normal Hearing ◽  
The Other ◽  
Personality Measures ◽  
Loudness Level

A number of experimental determinations of the uncomfortable loudness level (ULL) at 1000 Hz were made on several groups of normal-hearing subjects, using various methods of stimulus presentation and applying different personality measures to the subjects. The same mean levels were found for both earphone and free-field presentations. In experienced subjects the monaural-binaural difference was between 2.5 and 4 dB in different experiments. In naive subjects this difference was 6 dB. In two groups of subjects, ULL was found to be significantly negatively correlated with their test anxiety scores, but this correlation did not hold for the other two groups tested. Naive subjects showed little difference in intersubject variance with the manual or Bekesy presentation techniques.

scholarly journals The influence of vortices upon the resitance experienced by solids moving through a liquid

1928 ◽  
Vol 119 (781) ◽  
pp. 146-156 ◽  
Keyword(s):  
Perfect Fluid ◽  
Relative Motion ◽  
Constant Velocity ◽  
Fluid Motion ◽  
Resultant Force ◽  
The Other ◽  
Two Dimensional ◽  
Perfect Fluids ◽  
Potential Problems ◽  
The Moment

(1) It is not so long ago that it was generally believed that the "classical" hydrodynamics, as dealing with perfect fluids, was, by reason of the very limitations implied in the term "perfect," incapable of explaining many of the observed facts of fluid motion. The paradox of d'Alembert, that a solid moving through a liquid with constant velocity experienced no resultant force, was in direct contradiction with the observed facts, and, among other things, made the lift on an aeroplane wing as difficult to explain as the drag. The work of Lanchester and Prandtl, however, showed that lift could be explained if there was "circulation" round the aerofoil. Of course, in a truly perfect fluid, this circulation could not be produced—it does need viscosity to originate it—but once produced, the lift follows from the theory appropriate to perfect fluids. It has thus been found possible to explain and calculate lift by means of the classical theory, viscosity only playing a significant part in the close neighbourhood ("grenzchicht") of the solid. It is proposed to show, in the present paper, how the presence of vortices in the fluid may cause a force to act on the solid, with a component in the line of motion, and so, at least partially, explain drag. It has long been realised that a body moving through a fluid sets up a train of eddies. The formation of these needs a supply of energy, ultimately dissipated by viscosity, which qualitatively explains the resistance experienced by the solid. It will be shown that the effect of these eddies is not confined to the moment of their birth, but that, so long as they exist, the resultant of the pressure on the solid does not vanish. This idea is not absolutely new; it appears in a recent paper by W. Müller. Müller uses some results due to M. Lagally, who calculates the resultant force on an immersed solid for a general fluid motion. The result, as far as it concerns vortices, contains their velocities relative to the solid. Despite this, the term — ½ ρq 2 only was used in the pressure equation, although the other term, ρ ∂Φ / ∂t , must exist on account of the motion. (There is, by Lagally's formulæ, no force without relative motion.) The analysis in the present paper was undertaken partly to supply this omission and partly to check the result of some work upon two-dimensional potential problems in general that it is hoped to publish shortly.

scholarly journals Age effects on the development of stimulus over-selectivity are mediated by cognitive flexibility and selective attention

2020 ◽  
Vol 45 (1) ◽  
pp. 89-96
Author(s):  
Michelle P. Kelly ◽  
Phil Reed
Keyword(s):  
Selective Attention ◽  
Cognitive Flexibility ◽  
Visual Discrimination ◽  
Discrimination Task ◽  
The Other ◽  
Distractor Task ◽  
Typically Developing ◽  
Cognitive Variables ◽  
Typically Developing Children ◽  
Developmental Trends

Stimulus over-selectivity is said to have occurred when only a limited subset of the total number of stimuli present during discrimination learning controls behavior, thus, restricting learning about the range, breadth, or all features of a stimulus. The current study investigated over-selectivity of 100 typically developing children, aged 3–7 (mean = 65.50 ± 17.31 SD months), using a visual discrimination task. Developmental trends in over-selectivity and their relationship to some cognitive variables (i.e., selective attention, sustained attention, and cognitive flexibility) were the target. Over-selectivity decreased with age, but this effect was mediated by the development of cognitive flexibility. Over-selectivity increased when a distractor task was introduced, which was not mediated by the other cognitive variables under investigation. The current results assist in the establishment of the theoretical underpinnings of over-selectivity by offering evidence of its underlying determinants and relating these to developmental trends.

scholarly journals CONSTRAINING THE PREFERRED-FRAME α1, α2 PARAMETERS FROM SOLAR SYSTEM PLANETARY PRECESSIONS

2014 ◽  
Vol 23 (01) ◽  
pp. 1450006 ◽  
Author(s):  
L. IORIO
Keyword(s):  
Binary System ◽  
Solar System ◽  
Relative Motion ◽  
A Priori ◽  
The Other ◽  
Preferred Frame ◽  
General Relativistic ◽  
Ppn Parameters ◽  
Invariable Plane ◽  
Analytical Expressions

Analytical expressions for the orbital precessions affecting the relative motion of the components of a local binary system induced by Lorentz-violating Preferred Frame Effects (PFE) are explicitly computed in terms of the Parametrized Post-Newtonian (PPN) parameters α1, α2. Preliminary constraints on α1, α2 are inferred from the latest determinations of the observationally admitted ranges [Formula: see text] for any anomalous Solar System planetary perihelion precessions. Other bounds existing in the literature are critically reviewed, with particular emphasis on the constraint [Formula: see text] based on an interpretation of the current close alignment of the Sun's equator with the invariable plane of the Solar System in terms of the action of a α2-induced torque throughout the entire Solar System's existence. Taken individually, the supplementary precessions [Formula: see text] of Earth and Mercury, recently determined with the INPOP10a ephemerides without modeling PFE, yield α1 = (0.8±4) × 10-6 and α2 = (4±6) × 10-6, respectively. A linear combination of the supplementary perihelion precessions of all the inner planets of the Solar System, able to remove the a priori bias of unmodeled/mismodeled standard effects such as the general relativistic Lense–Thirring precessions and the classical rates due to the Sun's oblateness J2, allows to infer α1 = (-1 ± 6) × 10-6, α2 = (-0.9 ± 3.5) × 10-5. Such figures are obtained by assuming that the ranges of values for the anomalous perihelion precessions are entirely due to the unmodeled effects of α1 and α2. Our bounds should be improved in the near-mid future with the MESSENGER and, especially, BepiColombo spacecrafts. Nonetheless, it is worthwhile noticing that our constraints are close to those predicted for BepiColombo in two independent studies. In further dedicated planetary analyses, PFE may be explicitly modeled to estimate α1, α2 simultaneously with the other PPN parameters as well.

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