Quantitative determination of orientational and directional components in the response of visual cortical cells to moving stimuli

Wörgötter, Florentin; Eysel, Ulf

doi:10.1007/bf00354980

Cited by 100 publications

(79 citation statements)

References 19 publications

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“…Wörgötter & Eysel 1987;Wörgötter et al 1990;DeValois & DeValois 1990). These studies provide evidence that generalized stimuli covering large portions of the receptor surface can be well suited to predict responses to specific and/or more spatially restricted stimuli.…”

Section: Physiology Of Ripple Spectramentioning

confidence: 74%

Spectral integration plasticity in cat auditory cortex induced by perceptual training

et al. 2007

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We investigated the ability of cats to discriminate differences between vowel-like spectra, assessed their discrimination ability over time, and compared spectral receptive fields in primary auditory cortex (AI) of trained and untrained cats. Animals were trained to discriminate changes in the spectral envelope of a broad-band harmonic complex in a 2-alternative forced choice procedure. The standard stimulus was an acoustic grating consisting of a harmonic complex with a sinusoidally modulated spectral envelope ('ripple spectrum'). The spacing of spectral peaks was conserved at 1, 2, or 2.66 peaks/octave. Animals were trained to detect differences in the frequency location of energy peaks, corresponding to changes in the spectral envelope phase. Average discrimination thresholds improved continuously during the course of the testing from phase-shifts of 96° at the beginning to 44° after 4-6 months of training.Responses of AI single units and small groups of neurons to pure tones and ripple spectra were modified during perceptual discrimination training with vowel-like ripple stimuli. The transfer function for spectral envelope frequencies narrowed and the tuning for pure tones sharpened significantly in discriminant versus naive animals. By contrast, control animals that used the ripple spectra only in a lateralization task showed broader ripple transfer functions and narrower pure-tone tuning than naïve animals.

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Section: Physiology Of Ripple Spectramentioning

confidence: 74%

Spectral integration plasticity in cat auditory cortex induced by perceptual training

et al. 2007

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“…The spatial frequency bandwidth at half-maximal height (SF bw ), in cycles per degree (cpd), was calculated as 1.65␣ and subsequently converted to octaves. The orientation tuning was characterized as orientation bias (OB) (Wörgötter and Eysel, 1987;Leventhal et al, 2003), which is a complex number incorporating all of the data points on the tuning curve within a vector summation:…”

Section: Methodsmentioning

confidence: 99%

Functional Organization of Envelope-Responsive Neurons in Early Visual Cortex: Organization of Carrier Tuning Properties

Baker

2012

J. Neurosci.

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It is well established that visual cortex neurons having similar selectivity for orientation, direction of motion, ocular dominance, and other properties of first-order (luminance-defined) stimuli are clustered into a columnar organization. However, the cortical architecture of neuronal responses to second-order (contrast/texture-defined) stimuli is poorly understood. A useful second-order stimulus is a contrast envelope, consisting of a finely detailed pattern (carrier) whose contrast varies on a coarse spatial scale (envelope). In this study, we analyzed the cortical organization of carrier tuning properties of neurons, which responded to contrast-modulated stimuli. We examined whether neurons tuned to similar carrier properties are clustered spatially and whether such spatial clusters are arranged in columns. To address these questions, we recorded single-unit activity, multiunit activity, and local field potentials simultaneously from area 18 of anesthetized cats, using single-channel microelectrodes and multielectrode arrays. Our data showed that neurons tuned to similar carrier spatial frequency are distributed in a highly clustered manner; neurons tuned to similar carrier orientation are also significantly clustered. Neurons along linear arrays perpendicular to the brain surface always exhibited similar optimal carrier spatial frequency, indicating a columnar organization. Multi-pronged tetrode recordings indicated that the diameter of these columns is Ն450 m. Optimal carrier orientation was also significantly clustered but with finer-grain organization and greater scatter. These results indicate a fine anatomical structure of cortical organization of second-order information processing and suggest that there are probably more maps in cat area 18 than previously believed.

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“…The within-group response pattern was represented on a polar plot using the radial position of each stimulus with respect to the center of the parametric configuration, and the unimodality of the selectivity was determined by a fast Fourier transform of these plots 42 . Unimodal selectivities will be reflected in a Fourier spectrum dominated by the firstorder component.…”

Section: Recordings It Recordingsmentioning

confidence: 99%

Inferotemporal neurons represent low-dimensional configurations of parameterized shapes

2001

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articlesThe capacity to categorize stimuli is fundamental to all living organisms 1,2 . Theories of categorization agree upon the importance of the similarity between stimuli to account for many aspects of categorization performance [3][4][5] . However, it is not straightforward to compute the degree of similarity between stimuli that can vary across a high number of dimensions, like complex shapes. Fortunately, the similarities among a set of complex stimuli can often be described in a more compact way [6][7][8] . Indeed, stimuli from many behaviorally relevant sets can be represented in a low-dimensional representation space in which the proximity between stimuli is related to their similarity. For example, by presenting the randomly ordered shapes of Fig. 1d in a particular order (Fig. 1a-c), the similarities can be easily described by a twodimensional square-like configuration. Several behavioral studies that have varied complex shape differences parametrically revealed that primates are able to represent the similarities between shapes in a low-dimensional representation space without ever seeing these stimuli in their parametric configuration 9-12 .Here we aim to study directly the neural basis of these lowdimensional representation spaces. Object recognition and categorization in macaques is thought to depend on the inferotemporal cortex (IT) 13,14 . Single IT neurons are selective for moderately complex object features 15 , but several studies have found little relationship between the similarities between complex objects and the responses of single IT neurons 16,17 . However, one needs to manipulate shape similarity parametrically to investigate how the responses of IT neurons to complex stimuli are related to the proximity of these stimuli in a low-dimensional space. Thus, we investigated whether the response pattern across a population of IT neurons can reveal a low-dimensional and faithful representation of shape similarity using parameterized shapes. Behavioral studies with parameterized shapes have shown that the similarities among these complex stimuli can be represented using a low number of dimensions. Using psychophysical measurements and single-cell recordings in macaque inferotemporal (IT) cortex, we found an agreement between low-dimensional parametric configurations of shapes and the representation of shape similarity at the behavioral and neuronal level. The shape configurations, computed from both the perceived and neuron-based similarities, revealed a low number of dimensions and contained the same stimulus order as the parametric configurations. However, at a metric level, the behavioral and neural representations deviated consistently from the parametric configurations. These findings suggest an ordinally faithful but metrically biased representation of shape similarity in IT.As the analysis of the visual input in the visual system is highly nonlinear, the neuronal representation space could deviate from the configurations in parameter space in several ways. Previous psychophysical stu...

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Quantitative determination of orientational and directional components in the response of visual cortical cells to moving stimuli

Cited by 100 publications

References 19 publications

Spectral integration plasticity in cat auditory cortex induced by perceptual training

Spectral integration plasticity in cat auditory cortex induced by perceptual training

Functional Organization of Envelope-Responsive Neurons in Early Visual Cortex: Organization of Carrier Tuning Properties

Inferotemporal neurons represent low-dimensional configurations of parameterized shapes

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