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Université de Fribourg

Divergent solutions to visual problem solving across mammalian species

Mustafar, Faiz ; Harvey, Michael A. ; Khani, Abbas ; Arató, József ; Rainer, Gregor

In: eNeuro, 2018, vol. 5, no. 4, p. -

Our understanding of the neurobiological underpinnings of learning and behavior relies on the use of invasive techniques, which necessitate the use of animal models. However, when different species learn the same task, to what degree are they actually producing the same behavior and engaging homologous neural circuitry? This question has received virtually no recent attention, even as the...

Université de Fribourg

Distinct frequency specialization for detecting dark transients in humans and tree shrews

Khani, Abbas ; Mustafar, Faiz ; Rainer, Gregor

In: Cell Reports, 2018, vol. 23, no. 8, p. 2405–2415

Despite well-known privileged perception of dark over light stimuli, it is unknown to what extent this dark dominance is maintained when visual transients occur in rapid succession, for example, during perception of moving stimuli. Here, we address this question using dark and light transients presented at different flicker frequencies. Although both human participants and tree shrews...

Université de Fribourg

Astrocytic and neuronal oxidative metabolism are coupled to the rate of glutamate–glutamine cycle in the tree shrew visual cortex

Sonnay, Sarah ; Poirot, Jordan ; Just, Nathalie ; Clerc, Anne-Catherine ; Gruetter, Rolf ; Rainer, Gregor ; Duarte, João M. N.

In: Glia, 2018, vol. 66, no. 3, p. 477–491

Astrocytes play an important role in glutamatergic neurotransmission, namely by clearing synaptic glutamate and converting it into glutamine that is transferred back to neurons. The rate of this glutamate–glutamine cycle (VNT) has been proposed to couple to that of glucose utilization and of neuronal tricarboxylic acid (TCA) cycle. In this study, we tested the hypothesis that glutamatergic...

Université de Fribourg

Basal forebrain activation enhances between-trial reliability of low-frequency local field potentials (LFP) and spiking activity in tree shrew primary visual cortex (V1)

Luna, Paolo De ; Veit, Julia ; Rainer, Gregor

In: Brain Structure and Function, 2017, vol. 222, no. 9, p. 4239–4252

Brain state has profound effects on neural processing and stimulus encoding in sensory cortices. While the synchronized state is dominated by low-frequency local field potential (LFP) activity, low-frequency LFP power is suppressed in the desynchronized state, where a concurrent enhancement in gamma power is observed. Recently, it has been shown that cortical desynchronization co-occurs with ...

Université de Fribourg

Neural coding of image structure and contrast polarity of Cartesian, hyperbolic and polar gratings in the primary and secondary visual cortex of the tree shrew

Poirot, Jordan ; Luna, Paolo De ; Rainer, Gregor

In: Journal of Neurophysiology, 2016, p. -

We comprehensively characterize spiking and visual evoked potential (VEP) activity in tree shrew V1 and V2 using Cartesian, hyperbolic and polar gratings. Neural selectivity to structure of Cartesian gratings was higher than other grating classes in both visual areas. From V1 to V2, structure selectivity of spiking activity increased, while corresponding VEP values tended to decrease, suggesting...

Université de Fribourg

Diversification of the cold-adapted butterfly genus Oeneis related to Holarctic biogeography and climatic niche shifts

Kleckova, I. ; Cesanek, M. ; Fric, Z. ; Pellissier, Loïc

In: Molecular Phylogenetics and Evolution, 2015, vol. 92, p. 255–265

Both geographical and ecological speciation interact during the evolution of a clade, but the relative contribution of these processes is rarely assessed for cold-dwelling biota. Here, we investigate the role of biogeography and the evolution of ecological traits on the diversification of the Holarctic arcto-alpine butterfly genus Oeneis (Lepidoptera: Satyrinae). We reconstructed the molecular...

Université de Fribourg

Tree shrews (Tupaia belangeri) exhibit novelty preference in the novel location memory task with 24-h retention periods

Nair, Jayakrishnan ; Topka, Marlene ; Khani, Abbas ; Isenschmid, Manuela ; Rainer, Gregor

In: Frontiers in Psychology - Cognitive Science, 2014, vol. 5, p. 303

Novelty preference is pervasive in mammalian species, and describes an inherent tendency to preferentially explore novelty. The novel location memory task studied here assesses the ability of animals to form accurate memories of a spatial configuration, consisting of several identical objects placed within an arena. Tree shrews were first familiarized with a particular object configuration during...