TY  - JOUR
A1  - Ehrenfeld, Stephan
A1  - Herbort, Oliver
A1  - Butz, Martin V.
T1  - Modular neuron-based body estimation: maintaining consistency over different limbs, modalities, and frames of reference
JF  - Frontiers in Computational Neuroscience
N2  - This paper addresses the question of how the brain maintains a probabilistic body state estimate over time from a modeling perspective. The neural Modular Modality Frame (nMMF) model simulates such a body state estimation process by continuously integrating redundant, multimodal body state information sources. The body state estimate itself is distributed over separate, but bidirectionally interacting modules. nMMF compares the incoming sensory and present body state information across the interacting modules and fuses the information sources accordingly. At the same time, nMMF enforces body state estimation consistency across the modules. nMMF is able to detect conflicting sensory information and to consequently decrease the influence of implausible sensor sources on the fly. In contrast to the previously published Modular Modality Frame (MMF) model, nMMF offers a biologically plausible neural implementation based on distributed, probabilistic population codes. Besides its neural plausibility, the neural encoding has the advantage of enabling (a) additional probabilistic information flow across the separate body state estimation modules and (b) the representation of arbitrary probability distributions of a body state. The results show that the neural estimates can detect and decrease the impact of false sensory information, can propagate conflicting information across modules, and can improve overall estimation accuracy due to additional module interactions. Even bodily illusions, such as the rubber hand illusion, can be simulated with nMMF. We conclude with an outlook on the potential of modeling human data and of invoking goal-directed behavioral control.
KW  - information
KW  - posterior parietal cortex
KW  - hand
KW  - population code
KW  - conflicting information
KW  - multimodal interaction
KW  - probabilistic inference
KW  - modular body schema
KW  - sensor fusion
KW  - multisensory perception
KW  - fusion
KW  - representation
KW  - multisensory processing
KW  - see
KW  - implementation
KW  - perspective
KW  - multisensory integration
KW  - population codes
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122253
VL  - 7
IS  - 148
ER  - 
TY  - JOUR
A1  - Xiu, Daiming
A1  - Geiger, Maximilian J.
A1  - Klaver, Peter
T1  - Emotional face expression modulates occipital-frontal effective connectivity during memory formation in a bottom-up fashion
JF  - Frontiers in Behavioral Neuroscience
N2  - This study investigated the role of bottom-up and top-down neural mechanisms in the processing of emotional face expression during memory formation. Functional brain imaging data was acquired during incidental learning of positive ("happy"), neutral and negative ("angry" or "fearful") faces. Dynamic Causal Modeling (DCM) was applied on the functional magnetic resonance imaging (fMRI) data to characterize effective connectivity within a brain network involving face perception (inferior occipital gyrus and fusiform gyrus) and successful memory formation related areas (hippocampus, superior parietal lobule, amygdala, and orbitofrontal cortex). The bottom-up models assumed processing of emotional face expression along feed forward pathways to the orbitofrontal cortex. The top-down models assumed that the orbitofrontal cortex processed emotional valence and mediated connections to the hippocampus. A subsequent recognition memory test showed an effect of negative emotion on the response bias, but not on memory performance. Our DCM findings showed that the bottom-up model family of effective connectivity best explained the data across all subjects and specified that emotion affected most bottom-up connections to the orbitofrontal cortex, especially from the occipital visual cortex and superior parietal lobule. Of those pathways to the orbitofrontal cortex the connection from the inferior occipital gyrus correlated with memory performance independently of valence. We suggest that bottom-up neural mechanisms support effects of emotional face expression and memory formation in a parallel and partially overlapping fashion.
KW  - medial temporal lobe
KW  - human orbitofrontal cortex
KW  - subsequent memory
KW  - recognition memory
KW  - fMRI
KW  - event-related fMRI
KW  - posterior parietal cortex
KW  - short-term-memory
KW  - human brain
KW  - prefrontal activity
KW  - neural mechanisms
KW  - Dynamic Causal Modeling
KW  - facial affect
KW  - memory formation
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143211
VL  - 9
IS  - 90
ER  -