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You searched for +publisher:"Universidade Federal de Minas Gerais" +contributor:("Jean-Christophe Houzel"). One record found.

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1. Ana Luiza Turchetti Maia. Modulação centro-contorno em campos receptivos do wulst visual.

Degree: 2011, Universidade Federal de Minas Gerais

Neurons in the primary visual cortex (V1) typically show response suppression when stimulated by oriented stimuli larger than their classical receptive fields (CRF). Here, we investigate the prevalence, strength and feature selectivity of center-surround modulation in the owl visual wulst, an area that presents close hodological and physiological similarities to V1. In total, we recorded 167 neurons using standard single-unit extracellular recordings in awake burrowing owls, Athene cunicularia. Our dataset consisted of units that presented evoked activity larger than baseline and were significantly modulated by stimulus size. In a subset of neurons (n=145), we evaluated the response to drifting sinusoidal grating of increasing size centered in the middle of CRF fitted with a difference of two integrated Gaussians, one modeling excitatory center mechanisms and the other one modeling inhibitory surround. Among well-fitted units (n=144), 88% of visual wulst neurons were suppressed by co-stimulating center and surround areas. The magnitude of this suppression was widely distributed (median=33%) and correlated to the ratio between center (median=2.17º, n=114) and surround sizes (median=7.84º, n=86). In most cells, the suppressive effect appeared already at the start of the response, up to 30ms after response latency. When stimulating with a surround patch of grating, 74% out of 38 units showed response levels similar to baseline. The remaining units reached this level only when the inner border of the surround patch was moved away from the CRF border. As we introduced a 0.9º gap between center and surround (n=28), absence of response change was observed in 78.6% and 57.2% of units when center and surround gratings were collinear and orthogonal, respectively. Stimulus contrast variation (10% and 97%, n=33) showed that CRF size in these neurons is not invariant, as it is slightly larger at low contrast in 88% of units. Besides, in 67% of neurons, suppression index was larger for higher contrast, showing a tendency to be less suppressed for larger receptive field sizes. We did not find facilitatory effects when surround was orthogonal to center. Mean CRF size, as well as suppression index, was statistically not different between simple and complex cells. However, in a subset of neurons with suppression >5% (n=66), 80.3% of the evaluated cells presented an increase in phase-modulation depth of the response as stimulus size was increased. We conclude that center-surround modulation in visual wulst neurons is a robust phenomenon, probably related to perceptual saliency.

Neurônios do córtex visual primário (V1) apresentam uma resposta tipicamente supressiva quando estimulados por estímulos orientados maiores que seu campo receptivo clássico (CRC). Neste trabalho investigamos a prevalência, magnitude e estímulo-dependência da modulação centro-contorno no wulst visual da coruja, uma área que apresenta estreitas similaridades hodológicas e fisiológicas com V1. Ao todo, registramos 167 neurônios utilizando técnicas padrão de…

Advisors/Committee Members: Jerome Paul Laurent Baron, Jerome Paul Laurent Baron, Mário Fiorani Júnior, Jean-Christophe Houzel, Christopher Kushmerick, Andre Ricardo Massensini.

Subjects/Keywords: Fisiologia Teses.; Modulação centro-contorno; Campo receptivo clássico; Wulst visual da coruja

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APA (6th Edition):

Maia, A. L. T. (2011). Modulação centro-contorno em campos receptivos do wulst visual. (Thesis). Universidade Federal de Minas Gerais. Retrieved from http://hdl.handle.net/1843/BUOS-8NNGV8

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Maia, Ana Luiza Turchetti. “Modulação centro-contorno em campos receptivos do wulst visual.” 2011. Thesis, Universidade Federal de Minas Gerais. Accessed September 24, 2020. http://hdl.handle.net/1843/BUOS-8NNGV8.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Maia, Ana Luiza Turchetti. “Modulação centro-contorno em campos receptivos do wulst visual.” 2011. Web. 24 Sep 2020.

Vancouver:

Maia ALT. Modulação centro-contorno em campos receptivos do wulst visual. [Internet] [Thesis]. Universidade Federal de Minas Gerais; 2011. [cited 2020 Sep 24]. Available from: http://hdl.handle.net/1843/BUOS-8NNGV8.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Maia ALT. Modulação centro-contorno em campos receptivos do wulst visual. [Thesis]. Universidade Federal de Minas Gerais; 2011. Available from: http://hdl.handle.net/1843/BUOS-8NNGV8

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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