Papers for the month of June 2013

"Emerging Structure-Function Relations in the Developing Face Processing System."
Cerebral Cortex, Jun 13. [Epub ahead of print]:

Mouse over here for a brief summary or click to open article in a new tab.To evaluate emerging structure-function relations in a neural circuit that mediates complex behavior, we investigated age-related differences among cortical regions that support face recognition behavior and the fiber tracts through which they transmit and receive signals using functional neuroimaging and diffusion tensor imaging. we observed a dynamic association between emerging structural and functional architecture in the developing brain may provide important clues about the mechanisms by which neural circuits become organized and optimized in the human cortex.

"Extending, changing, and explaining the brain"
Biology and Philosophy, 28:613-638

Mouse over here for a brief summary or click to open article in a new tab.This paper addresses concerns raised by Datteri (2009) and Craver (2010) about the value of BCI systems as a research tool, beyond neuro-engineering applications.

"Time course of motor preparation during visual search with flexible stimulus-response association"
The Journal of Neuroscience, 33:10057-65

Mouse over here for a brief summary or click to open article in a new tab.Whether allocation of visuospatial attention can be divorced from saccade preparation has been the subject of intense research efforts. We performed a causal assessment of this controversy by delivering an air puff to one eye to invoke the trigeminal blink reflex as monkeys performed a visual search task with a flexible stimulus-response association. Blinks effectively remove saccadic inhibition and prematurely trigger the impending saccade in reaction time tasks, thus providing a behavioral evaluation of the premotor plan. The blink-triggered saccades provide support for concurrent encoding of visuospatial attention and saccade preparation during visual search.

"Bodies adapt orientation-independent face representations"
Frontiers in Perception Science, 4:413

Mouse over here for a brief summary or click to open article in a new tab.Here we demonstrate that bodies without visible faces activate and adapt the representation of faces not according to the orientation of the body, but rather in an orientation independent manner.

"Identifying Emotions on the Basis of Neural Activation"
PLOS One, 2013:1

Mouse over here for a brief summary or click to open article in a new tab.We attempt to determine the discriminability and organization of neural activation corresponding to the experience of specific emotions. Method actors were asked to self-induce nine emotional states (anger, disgust, envy, fear, happiness, lust, pride, sadness, and shame) while in an fMRI scanner. Using a Gaussian Naïve Bayes pooled variance classifier, we demonstrate the ability to identify specific emotions experienced by an individual at well over chance accuracy on the basis of: 1) neural activation of the same individual in other trials, 2) neural activation of other individuals who experienced similar trials, and 3) neural activation of the same individual to a qualitatively different type of emotion induction. Factor analysis identified valence, arousal, sociality, and lust as dimensions underlying the activation patterns. These results suggest a structure for neural representations of emotion and inform theories of emotional processing.

"The nuisance of nuisance regression: Spectral misspecification in a common approach to resting-state fMRI preprocessing reintroduces noise and obscures functional connectivity"
NeuroImage, 82:208-225

Mouse over here for a brief summary or click to open article in a new tab.Bandpass filtering and nuisance regression are intended to reduce noise in resting-state fMRI research, yet when fMRI data are filtered, but regressors are not, noise is poorly controlled and synchronous noise in introduced into the fMRI data. We demonstrate that simultaneous bandpass filtering and nuisance regression eliminates this source of bias and better controls for noise in resting-state fMRI data.

"White matter microstructure, alcohol exposure, and familial risk for alchol dependence"
Psychiatry Research Neuroimaging, 212:43-53

Mouse over here for a brief summary or click to open article in a new tab.Offspring from families with alcohol dependence were contrasted with offspring from control families using diffusion tensor imaging to determine if differences in white matter tracts would be seen. Results show that both familial loading for alcohol dependence and personal alcohol exposure contribute to white matter integrity of selected tracts.

"Limited Encoding of Effort by Dopamine Neurons in a Cost-Benefit Trade-off Task"
The Journal of Neuroscience, 33(19):8288-8300

Mouse over here for a brief summary or click to open article in a new tab.Animals are thought to evaluate the desirability of action options using a unified scale that combines predicted benefits (“rewards”), costs, and the animal’s internal motivational state. Midbrain dopamine neurons have long been associated with the reward part of this equation, but it is unclear whether these neurons also estimate the costs of taking an action. We studied the spiking activity of dopamine neurons in the substantia nigra pars compacta of monkeys (Macaca mulatta) during a reaching task in which the energetic costs incurred (friction loads) and the benefits gained (drops of food) were manipulated independently. Although the majority of dopamine neurons encoded the upcoming reward alone, a subset predicted net utility of a course of action by signaling the expected reward magnitude discounted by the invested cost in terms of physical effort. In addition, the tonic activity of some dopamine neurons was slowly reduced in conjunction with the accumulated trials, which is consistent with the hypothesized role for tonic dopamine in the invigoration or motivation of instrumental responding. The present results shed light on an often-hypothesized role for dopamine in the regulation of the balance in natural behaviors between the energy expended and the benefits gained, which could explain why dopamine disorders, such as Parkinson’s disease, lead to a breakdown of that balance.
Archive: May 2013