Biomedical subjects

Scott L Fairhall

Publications and source records attributed to Scott L Fairhall.

3 recordsLinked to original sources

PubMed2006

Effective connectivity within the distributed cortical network for face perception.

Face perception elicits activation within a distributed cortical network in the human brain. The network includes visual ("core") regions, as well as limbic and prefrontal ("extended") regions, which process invariant facial features and changeable aspects of faces, respectively. We used functional Magnetic Resonance Imaging and Dynamic Causal Modeling to investigate effective connectivity and functional organization between and within the core and the extended systems. We predicted a ventral rather than dorsal connection between the core and the extended systems during face viewing and tested whether valence and fame would alter functional coupling within the network. We found that the core system is hierarchically organized in a predominantly feed-forward fashion, and that the fusiform gyrus (FG) exerts the dominant influence on the extended system. Moreover, emotional faces increased the coupling between the FG and the amygdala, whereas famous faces increased the coupling between the FG and the orbitofrontal cortex. Our results demonstrate content-specific dynamic alterations in the functional coupling between visual-limbic and visual-prefrontal face-responsive pathways.

Adult↗

PubMed2006

Volition and the idle cortex: beta oscillatory activity preceding planned and spontaneous movement.

Prior to the initiation of spontaneous movement, evoked potentials can be seen to precede awareness of the impending movement by several hundreds of milliseconds, meaning that this recorded neural activity is the result of unconscious processing. This study investigates the neural representations of impending movement with and without awareness. Specifically, the relationship between awareness and 'idling' cortical oscillations in the beta range (18-24Hz) was assessed. It was found that, in situations where there was awareness of the impending movement, pre-movement evoked potentials were associated with a decrease in beta range oscillations. In contrast, when awareness of the impending movement was not present, the onset of the pre-movement potential was associated with tonic levels of beta range oscillations. A model is considered where by distributed neural activity remains outside of conscious awareness through the persistence of tonic slow wave cortical oscillations.

Adult↗

PubMed2006

Temporal dynamics of masked word reading.

The repercussions of unconscious priming on the neural correlates subsequent cognition have been explored previously. However, the neural dynamics during the unconscious processing remains largely uncharted. To assess both the complexity and temporal dynamics of unconscious cognition the present study contrasts the evoked response from classes of masked stimuli with three different levels of complexity; words, consonant strings, and blanks. The evoked response to masked word stimuli differed from both consonant strings and blanks, which did not differ from each other. This response was qualitatively different to any evoked potential observed when stimuli were consciously visible and peaked at 140ms, earlier than is usually associated with differences between words and strings and 100ms earlier than word-consonant string differences in the visible condition. The evoked response demonstrates a qualitatively distinct signature of unconscious cognition and directly demonstrates the extraction of abstract information under subliminal conditions.

Adult↗