Friday, March 12, 2010

Two views of brain function

Two views of brain function:

Publication year: 2010
Source: Trends in Cognitive Sciences, In Press, Corrected Proof, Available online 4 March 2010
Marcus E., Raichle

Traditionally studies of brain function have focused on task-evoked responses. By their very nature, such experiments tacitly encourage a reflexive view of brain function. Although such an approach has been remarkably productive, it ignores the alternative possibility that brain functions are mainly intrinsic, involving information processing for interpreting, responding to and predicting environmental demands. Here I argue that the latter view best captures the essence of brain function, a position that accords well with the allocation of the brain's energy resources. Recognizing the importance of intrinsic activity will require integrating knowledge from cognitive and systems neuroscience with cellular and molecular..."

A New Spin on Conductivity: Electric Signals Can Propagate through an Insulator

Possible inorganic myelin sheath?

A New Spin on Conductivity: Electric Signals Can Propagate through an Insulator:

An electric insulator, in the simplest terms, blocks the flow of electric current. So it would be a bit counterintuitive, to say the least, if a current on one side of an insulator could produce voltage on the other. [More]

Friday, March 05, 2010

Reduced Neural Selectivity Increases fMRI Adaptation with Age during Face Discrimination

Key project finally published! This took quite a while, but it was worth it.

[Link to article if you have journal access]
[Link to Pubmed abstract access]

By Joshua O., Goh , Atsunobu, Suzuki , Denise C., Park
Beckman Institute, University of Illinois, Urbana-Champaign, IL, USA; Center for Vital Longevity, University of Texas, Dallas, TX, USA.

Ventral-visual activity in older adults has been characterized by dedifferentiation, or reduced distinctiveness, of responses to different categories of visual stimuli such as faces and houses, that typically elicit highly specialized responses in the fusiform and parahippocampal brain regions respectively in young adults (Park et al., 2004). In the present study, we demonstrate that age-related neural dedifferentiation applies to within-category stimuli (different types of faces) as well, such that older adults process less distinctive representations for individual faces than young adults. We performed a functional magnetic resonance imaging adaptation experiment while young and older participants made same-different judgments to serially presented face-pairs that were Identical, Moderate in similarity through morphing, or Different. As expected, older adults showed adaptation in the fusiform face area (FFA), during the Identical as well as the Moderate conditions relative to the Different condition. Young adults showed adaptation during the Identical condition, but minimal adaptation to the Moderate condition. These results indicate that older adults' FFA treated the morphed faces as Identical faces, reflecting decreased fidelity of neural representation of faces with age.

NeuroImage, In Press, Accepted Manuscript, Available online 6 February 2010