Université de Fribourg

Effects of lactate on the early visual cortex of non-human primates, investigated by pharmaco-MRI and neurochemical analysis

Pföstl, Veronika von ; Li, Juan ; Zaldivar, Daniel ; Goense, Jozien ; Zhang, Xiaozhe ; Serr, Nadine ; Logothetis, Nikos K. ; Rauch, Alexander

In: NeuroImage, 2012, vol. 61, no. 1, p. 98–105

In contrast to the limited use of functional magnetic resonance imaging (fMRI) in clinical diagnostics, it is currently a mainstay of neuroimaging in clinical and basic brain research. However, its non-invasive use in combination with its high temporal and spatial resolution would make fMRI a perfect diagnostic tool. We are interested in whether a pharmacological challenge imposed on the brain...

Université de Fribourg

Theta coupling between V4 and prefrontal cortex predicts visual short-term memory performance

Liebe, Stefanie ; Hoerzer, Gregor M. ; Logothetis, Nikos K. ; Rainer, Gregor

In: Nature Neuroscience, 2012, vol. 15, no. 3, p. 456-464

Short-term memory requires communication between multiple brain regions that collectively mediate the encoding and maintenance of sensory information. It has been suggested that oscillatory synchronization underlies intercortical communication. Yet, whether and how distant cortical areas cooperate during visual memory remains elusive. We examined neural interactions between visual area V4 and...

Université de Fribourg

Own-species bias in the representations of monkey and human face categories in the primate temporal lobe

Sigala, R. ; Logothetis, Nikos K. ; Rainer, Gregor

In: Journal of Neurophysiology, 2011, vol. 105, no. 6, p. 2740-2752

Face categorization is fundamental for social interactions of primates and is crucial for determining conspecific groups and mate choice. Current evidence suggests that faces are processed by a set of well-defined brain areas. What is the fine structure of this representation, and how is it affected by visual experience? Here, we investigated the neural representations of human and monkey face...

Université de Fribourg

Dissociable effects of natural image structure and color on LFP and spiking activity in the lateral prefrontal cortex and extrastriate visual area V4

Liebe, Stefanie ; Logothetis, Nikos K. ; Rainer, Gregor

In: The Journal of Neuroscience, 2011, vol. 31, no. 28, p. 10215-10227

Visual perception is mediated by unique contributions of the numerous brain regions that constitute the visual system. We performed simultaneous recordings of local field potentials (LFPs) and single unit activity (SUA) in areas V4 and lateral prefrontal cortex to characterize their contribution to visual processing. Here, we trained monkeys to identify natural images at different degradation...

Université de Fribourg

Directed coupling in local field potentials of macaque V4 during visual short-term memory revealed by multivariate autoregressive models

Hoerzer, Gregor M. ; Liebe, Stefanie ; Schloegl, Alois ; Logothetis, Nikos K. ; Rainer, Gregor

In: Frontiers in Computational Neuroscience, 2010, vol. 4, no. 14, p. -

Processing and storage of sensory information is based on the interaction between different neural populations rather than the isolated activity of single neurons. In order to characterize the dynamic interaction and transient cooperation of sub-circuits within a neural network, multivariate autoregressive (MVAR) models have proven to be an important analysis tool. In this study, we apply...

Université de Fribourg

Temporal kernel CCA and its application in multimodal neuronal data analysis

Bießmann, Felix ; Meinecke, Contact Information, Frank C. ; Gretton, Contact Information, Arthur ; Rauch, Alexander ; Rainer, Gregor ; Logothetis, Nikos K. ; Müller, Klaus-Robert

In: Machine Learning, 2010, vol. 79, no. 1-2, p. 5-27

Data recorded from multiple sources sometimes exhibit non-instantaneous couplings. For simple data sets, cross-correlograms may reveal the coupling dynamics. But when dealing with high-dimensional multivariate data there is no such measure as the cross-correlogram. We propose a simple algorithm based on Kernel Canonical Correlation Analysis (kCCA) that computes a multivariate temporal filter...

Université de Fribourg

Color and shape interactions in the recognition of natural scenes by human and monkey observers

Liebe, Stefanie ; Fischer, Elvira ; Logothetis, Nikos K. ; Rainer, Gregor

In: Journal of Vision, 2009, vol. 9, no. 5, p. 14

Trichromatic color vision is a fundamental aspect of the visual system shared by humans and non-human primates. In human observers, color has been shown to facilitate object identification. However, little is known about the role that color plays in higher level vision of non-human primates. Here, we addressed this question and studied the interaction between luminance- and color-based structural...