170,831 research outputs found
On the use of information theory for the analysis of the relationship between neural and imaging signals
No full textFunctional magnetic resonance imaging (fMRI) is a widely used method for studying the neural basis of cognition and of sensory function. A potential problem in the interpretation of fMRI data is that fMRI measures neural activity only indirectly, as a local change of deoxyhemoglobin concentration due to the metabolic demands of neural function. To build correct sensory and cognitive maps in the human brain, it is thus crucial to understand whether fMRI and neural activity convey the same type of information about external correlates. While a substantial experimental effort has been devoted to the simultaneous recordings of hemodynamic and neural signals, so far, the development of analysis methods that elucidate how neural and hemodynamic signals represent sensory information has received less attention. In this article, we critically review why the analytical framework of information theory, the mathematical theory of communication, is ideally suited to this purpose. We review the principles of information theory and explain how they could be applied to the analysis of fMRI and neural signals. We show that a critical advantage of information theory over more traditional analysis paradigms commonly used in the fMRI literature is that it can elucidate, within a single framework, whether an empirically observed correlation between neural and fMRI signals reflects either a similar stimulus tuning or a common source of variability unrelated to the external stimuli. In addition, information theory determines the extent to which these shared sources of stimulus signal and of variability lead fMRI and neural signals to convey similar information about external correlates. We then illustrate the formalism by applying it to the analysis of the information carried by different bands of the local field potential. We conclude by discussing the current methodological challenges that need to be addressed to make the information-theoretic approach more robustly applicable to the simultaneous recordings of neural and imaging data
Lost without a map: Pursuing primate homologies with functional imaging.
No full textPetkov CI, Kayser C, Logothetis N. Lost without a map: Pursuing primate homologies with functional imaging. In: Brain Mapping Research Trends. New York: Nova Science; 2008: 174-194
Visual modulation of neurons in auditory cortex
No full textKayser C, Petkov CI, Logothetis NK. Visual modulation of neurons in auditory cortex. Cereb Cortex. 2008;18(7):1560-74
Tuning to sound frequency in auditory field potentials
No full textKayser C, Petkov CI, Logothetis NK. Tuning to sound frequency in auditory field potentials. J Neurophysiol. 2007;98(3):1806-9
2-C-trifluoromethyl substituted pentoses
No full textThe synthesis of racemic 2-C-trifluoromethyl ribose and racemic 2-C-trifluoromethyl arabinose is described. The four step reaction sequence includes diastereoselective enol ether addition to methyl trifluoropyruvate, diastereoselective dihydroxylation of the CC double bond with potassium osmate, lactonization, and finally SMEAH reduction to give the lactol. 2-C-Trifluoromethyl pentoses exhibit unexpected anomeric and tautomeric stabilities
Synthese von trifluormethylsubstituierten Kohlenhydraten. Neue Strategien mit Methyl 3,3,3-trifluorpyruvat als building block für 2-C-Trifluormethylpentosen
No full text2-C-trifluoromethyl substituted 3-deoxypentoses
No full textAn efficient synthesis of 2-C-trifluoromethyl substituted 3-deoxypentoses starting from trifluoropyruvates is described
The electrophysiological Background of the fMRI Signal
No full textKayser C, Logothetis N. The electrophysiological Background of the fMRI Signal. In: Ulmer S, Jansen O, eds. fMRI. Basics and Clinical Applications. Berlin: Springer; 2009: 23-33
Fixations in natural scenes: interaction of image structure and image content
No full textKayser C, Nielsen KJ, Logothetis NK. Fixations in natural scenes: interaction of image structure and image content. Vision Res. 2006;46(16):2535-45
Imaging cross-modal influences in auditory cortex.
No full textKayser C, Petkov CI, Logothetis N. Imaging cross-modal influences in auditory cortex. In: Naumer M, Kaiser J, eds. Multisensory Object Perception in the Primate Brain. Springer; 2010: 123-137
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