Lauri Nurminen

University of Houston | U of H, UH · College of Optometry

A defining feature of the cortex is its laminar organization, which is likely critical for cortical information processing. For example, visual stimuli of different size evoke distinct patterns of laminar activity. Visual information processing is also influenced by the response variability of individual neurons and the degree to which this variabi...

Visual perception is affected by spatial context. In visual cortex, neuronal responses to stimuli inside the receptive field (RF) are suppressed by stimuli in the RF surround. To understand the circuits and cortical layers processing spatial context, we simultaneously recorded across all layers of macaque primary visual cortex while presenting stim...

Sensory information travels along feedforward connections through a hierarchy of cortical areas, which, in turn, send feedback connections to lower-order areas. Feedback has been implicated in attention, expectation, and sensory context, but the mechanisms underlying these diverse feedback functions are unknown. Using specific optogenetic inactivat...

In the cerebral cortex, sensory information travels along feedforward connections through a hierarchy of areas, which, in turn, send a denser network of feedback connections to lower-order areas. Feedback has been implicated in attention, expectation, and sensory context, but the cellular mechanisms underlying these diverse feedback functions are u...

Visual perception is profoundly affected by spatial context. In visual cortex, neuronal responses to stimuli inside their receptive field (RF) are suppressed by contextual stimuli in the RF surround (surround suppression). How do neuronal RFs integrate information across visual space, and what role do different cortical layers play in the processin...

Surround modulation (SM) is a fundamental property of sensory neurons in many species and sensory modalities. SM is the ability of stimuli in the surround of a neuron's receptive field (RF) to modulate (typically suppress) the neuron's response to stimuli simultaneously presented inside the RF, a property thought to underlie optimal coding of senso...

Neural responses to visual stimuli are strongest in the classical receptive field, but they are also modulated by stimuli in a much wider region. In the primary visual cortex, physiological data and models suggest that such contextual modulation is mediated by recurrent interactions between cortical areas. Outside the primary visual cortex, imaging...

The individual error between model and data at different eccentricities subtracted from error for all visual areas (VOIAVA). a–e) for ESN (see Fig. 7 legend for details). In each VOI, the data is restricted to a resampled subset of voxels to make the errors comparable. f–j) Same for ESF. The error bars show the standard error of mean across all act...

Same as Fig. S2 but for different functional areas. a–f) ESN g–l) ESF. (TIF)

Significance of BOLD signals spread and the suppressive and facilitative interactions for the Subject 3 (data points in Figure 2).“+” sign means significantly positive (sign test, p<0.05) and “–” sign means significantly negative (p<0.05) value. The test was conducted across voxels in each VOI. (DOCX)

As in Table S1, but for the group analysis (data points in Figure 3). The test was conducted across subjects. (DOCX)

Fitting a 3rd order polynomial (a–d) and linear (e–h) functions to correlation between C and S vectors versus average dM, (See Fig. 6). First data for 14 subjects was included for fitting, and one subject was left out. Then the procedure was repeated for all the subjects (dashed gray lines (a–d) and light blue lines (e–h)). The left and right colum...

A visual stimulus activates different sized cortical area depending on eccentricity of the stimulus. Here, our aim is to understand whether the visual field size of a stimulus or cortical size of the corresponding representation determines how strongly it interacts with other stimuli. We measured surround modulation of blood-oxygenation-level-depen...

In primary visual cortex (V1), neuronal responses to stimuli inside the receptive field (RF) are usually suppressed by stimuli in the RF surround. This suppression is orientation specific. Similarly, in human vision surround stimuli can suppress perceived contrast of a central stimulus in an orientation-dependent manner. The surround consists of tw...

The percept of a contrast target is substantially affected by co-occurring changes in mean luminance or underlying ("pedestal") contrast elements. These two types of modulatory effects have traditionally been studied as separate phenomena. However, regardless of different higher-level mechanisms, both classes of phenomena will necessarily also depe...

When we are viewing natural scenes, every saccade abruptly changes both the mean luminance and the contrast structure falling on any given retinal location. Thus it would be useful if the two were independently encoded by the visual system, even when they change simultaneously. Recordings from single neurons in the cat visual system have suggested...

Surround modulation of perceived contrast has been almost exclusively studied in short-range conditions, i.e., in situations where a tiny gap, at most, separates center from surround. Existing long-range studies suggest that suppression extends to 12-cycle distance, whereas facilitation of perceived contrast is suggested to arise from visual field...

Contextual modulation is a fundamental feature of sensory processing, both on perceptual and on single-neuron level. When the diameter of a visual stimulus is increased, the firing rate of a cell typically first increases (summation field) and then decreases (surround field). Such an area summation function draws a comprehensive profile of the rece...

Human medial occipital cortex comprises multiple visual areas, each with a distinct retinotopic representation of visual environment. We measured spatial frequency (SF) tuning curves with functional magnetic resonance imaging (fMRI) and found consistent differences between these areas. Areas V1, V2, VP, V3, V4v, and V3A were all band-pass tuned, wi...