Cognitive neuroscience 2.0: building a cumulative science of human brain function

 

http://www.cell.com/trends/cognitive-sciences/abstract/S1364-6613(10)00201-9

 

Interpreting brain images: reflections on an adolescent field

Book review; the book might be interesting.

 

 

Feed: TRENDS IN COGNITIVE SCIENCES
Posted on: dinsdag 28 september 2010 6:00
Author: TRENDS IN COGNITIVE SCIENCES
Subject: Interpreting brain images: reflections on an adolescent field

 

Nikolaus Kriegeskorte.

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Optogenetic interrogation of neural circuits: technology for probing mammalian brain structures

http://www.nature.com/nprot/journal/v5/n3/full/nprot.2009.226.html

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Naoki Kogo, PhD
Laboratory of Experimental Psychology
Department of Psychology, University of Leuven, Belgium
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Optogenetic fMRI Sheds Light on the Neural Basis of the BOLD Signal

 

 

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Optogenetic fMRI Sheds Light on the Neural Basis of the BOLD Signal

via Journal of Neurophysiology current issue by Palmer, H. S. on 10/4/10

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used as a measure of neuronal activity, despite an incomplete understanding of the hemodynamic and neural bases for BOLD signals. Recent work by Lee and colleagues investigated whether activating genetically specified neurons elicits BOLD responses. Integrating optogenetic control of specific cells and fMRI showed that stimulating excitatory neurons triggers a positive BOLD signal with conventional kinetics locally and delayed weaker BOLD signals distally.

 

 

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Global and local fMRI signals driven by neurons defined optogenetically by t...

 

 

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Global and local fMRI signals driven by neurons defined optogenetically by type and wiring

via Nature - Issue - nature.com science feeds by Karl Deisseroth on 5/16/10

Global and local fMRI signals driven by neurons defined optogenetically by type and wiring

Nature 465, 788 (2010). doi:10.1038/nature09108

Authors: Jin Hyung Lee, Remy Durand, Viviana Gradinaru, Feng Zhang, Inbal Goshen, Dae-Shik Kim, Lief E. Fenno, Charu Ramakrishnan & Karl Deisseroth

Despite a rapidly-growing scientific and clinical brain imaging literature based on functional magnetic resonance imaging (fMRI) using blood oxygenation level-dependent (BOLD) signals, it remains controversial whether BOLD signals in a particular region can be caused by activation of local excitatory neurons. This difficult question is central to the interpretation and utility of BOLD, with major significance for fMRI studies in basic research and clinical applications. Using a novel integrated technology unifying optogenetic control of inputs with high-field fMRI signal readouts, we show here that specific stimulation of local CaMKIIα-expressing excitatory neurons, either in the neocortex or thalamus, elicits positive BOLD signals at the stimulus location with classical kinetics. We also show that optogenetic fMRI (ofMRI) allows visualization of the causal effects of specific cell types defined not only by genetic identity and cell body location, but also by axonal projection target. Finally, we show that ofMRI within the living and intact mammalian brain reveals BOLD signals in downstream targets distant from the stimulus, indicating that this approach can be used to map the global effects of controlling a local cell population. In this respect, unlike both conventional fMRI studies based on correlations and fMRI with electrical stimulation that will also directly drive afferent and nearby axons, this ofMRI approach provides causal information about the global circuits recruited by defined local neuronal activity patterns. Together these findings provide an empirical foundation for the widely-used fMRI BOLD signal, and the features of ofMRI define a potent tool that may be suitable for functional circuit analysis as well as global phenotyping of dysfunctional circuitry.

 

 

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Modeling and analyzing mechanisms underlying fMRI-based decoding of information conveyed in cortical columns

 

Feed: ScienceDirect Publication: NeuroImage
Posted on: donderdag 23 september 2010 7:04
Author: ScienceDirect Publication: NeuroImage
Subject: Modeling and analyzing mechanisms underlying fMRI-based decoding of information conveyed in cortical columns

 

Publication year: 2010 Source: NeuroImage, In Press, Accepted Manuscript, Available online 22 September 2010 Denis, Chaimow , Essa, Yacoub , Kamil, Ugurbil , Amir, Shmuel Multivariate machine learning algorithms applied to human functional MRI (fMRI) data can decode information conveyed by cortical columns, despite the voxel-size being large relative to the width of columns. Several mechanisms have been proposed to underlie decoding of stimulus orientation or the stimulated eye. These include: (I) aliasing of high spatial-frequency components, including the main frequency of the columnar organization by the large voxels, (II) contributions from local irregularities in the columnar organization, (III) contributions from large-scale non-columnar organizations (IV), functionally selective veins with biased draining regions, and (V) complex spatio-temporal filtering of neuronal activity by fMRI voxels. Here we...

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Self-organisation in the human visual system–visuo-motor processing with congenitally abnormal V1 input

 

Feed: ScienceDirect Publication: Neuropsychologia
Posted on: woensdag 22 september 2010 6:25
Author: ScienceDirect Publication: Neuropsychologia
Subject: Self-organisation in the human visual system–visuo-motor processing with congenitally abnormal V1 input

 

Publication year: 2010 Source: Neuropsychologia, In Press, Accepted Manuscript, Available online 21 September 2010 Barbara, Wolynski , Martin, Kanowski , Synke, Meltendorf , Wolfgang, Behrens-Baumann , Michael B., Hoffmann Due to an abnormal projection of the temporal retina the albinotic primary visual cortex receives substantial input from the ipsilateral visual field. To test whether representation abnormalities are also evident in higher tier visual, and in motor and somatosensory cortices, brain activity was measured with fMRI in 14 subjects with albinism performing a visuo-motor task. During central fixation, a blue or red target embedded in a distractor array was presented for 250ms in the left or right visual hemifield. After a delay, the subjects were prompted to indicate with left or right thumb button presses the target presence in the...

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