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Nancy J Lobaugh

Publications and source records attributed to Nancy J Lobaugh.

7 recordsLinked to original sources
PubMed2006

Children recruit distinct neural systems for implicit emotional face processing.

The ability to properly distinguish facial emotions has a protracted development, not maturing until well into adolescence. Emotional faces activate emotion-specific neural networks in adults; whether these networks are operational in children is not known. Using an implicit face-processing task in 10-year-old children, we determined that the emotions of fear, disgust and sadness recruited distinct neural systems. These systems included a number of regions typically associated with processing emotions in adults, namely the amygdala and parahippocampal gyrus, insula and cingulate gyrus, as well as the fusiform and superior temporal gyri. Thus, in spite of immature behavioral responses to emotional faces in explicit tasks, neural networks for emotion-specific processing are present in young children.

Brain↗
PubMed2005

Neuroanatomical differences between mouse strains as shown by high-resolution 3D MRI.

The search for new mouse models of human disease requires a sensitive metric to make three-dimensional (3D) anatomical comparisons in a rapid and quantifiable manner. This is especially true in the brain, where changes in complex shapes such as the hippocampus and ventricles are difficult to assess with 2D histology. Here, we report that the 3D neuroanatomy of three strains of mice (129S1/SvImJ, C57/Bl6, and CD1) is significantly different from one another. Using image co-registration, we 'morphed' together nine brains of each strain scanned by magnetic resonance imaging at (60 microm)3 resolution to synthesize an average image. We applied three methods of comparison. First, we used visual inspection and graphically examined the standard deviation of the variability in each strain. Second, we annotated 42 neural structures and compared their volumes across the strains. Third, we assessed significant local deviations in volume and displacement between the two inbred strains, independent of prior anatomical knowledge.

Algorithms↗
PubMed2005

Accelerated and amplified neural responses in visual discrimination: Two features are processed faster than one.

Psychological and neurophysiological models of visual processing have traditionally emphasized hierarchical models to explain how separate features of visual stimuli are combined. This concept has been challenged recently with the demonstration of simultaneous activation of multiple visual areas and rapid feedback to primary cortices. Here, we show human visual processing may involve similar mechanisms. Subjects discriminated targets from nontargets as a function of shape, color, or the conjunction of these features while event-related brain potentials (ERPs) were recorded. ERP components from 100 to 200 ms across posterior occipital-temporal cortices were fastest and largest for conjunction targets. These enhanced early responses were followed by task-specific sustained posterior activity (300-500 ms). Faster reaction times were correlated with enhanced and faster early processing in the visual ventral areas. These data demonstrate the human visual system conjoins features rapidly, accelerating and amplifying the processing of relevant stimulus dimensions.

Adult↗
PubMed2004

Partial least squares analysis of neuroimaging data: applications and advances.

Partial least squares (PLS) analysis has been used to characterize distributed signals measured by neuroimaging methods like positron emission tomography (PET), functional magnetic resonance imaging (fMRI), event-related potentials (ERP) and magnetoencephalography (MEG). In the application to PET, it has been used to extract activity patterns differentiating cognitive tasks, patterns relating distributed activity to behavior, and to describe large-scale interregional interactions or functional connections. This paper reviews the more recent extension of PLS to the analysis of spatiotemporal patterns present in fMRI, ERP, and MEG data. We present a basic mathematical description of PLS and discuss the statistical assessment using permutation testing and bootstrap resampling. These two resampling methods provide complementary information of the statistical strength of the extracted activity patterns (permutation test) and the reliability of regional contributions to the patterns (bootstrap resampling). Simulated ERP data are used to guide the basic interpretation of spatiotemporal PLS results, and examples from empirical ERP and fMRI data sets are used for further illustration. We conclude with a discussion of some caveats in the use of PLS, including nonlinearities, nonorthogonality, and interpretation difficulties. We further discuss its role as an important tool in a pluralistic analytic approach to neuroimaging.

Adult↗
PubMed2004

Spatiotemporal analysis of event-related potentials to upright, inverted, and contrast-reversed faces: effects on encoding and recognition.

In an n-back face recognition task where subjects responded to repeated stimuli, ERPs were recorded to upright, inverted, and contrast-reversed faces. The effects of inversion and contrast reversal on face encoding and recognition were investigated using the multivariate spatiotemporal partial least squares (PLS) analysis. The configural manipulations affected early processing (100-200 ms) at posterior sites: Inversion effects were parietal and lateral, whereas contrast-reversal effects were more occipital and medial, suggesting different underlying generators. A later reactivation of face processing areas was unique to inverted faces, likely due to processing difficulties. PLS also indicated that the "old-new" repetition effect was maximal for upright faces and likely involved frontotemporal areas. Marked processing differences between inverted and contrast-reversed faces were seen, but these effects were similar at encoding and recognition.

Adult↗
PubMed2003

Functional connectivity of the medial temporal lobe relates to learning and awareness.

Learning with awareness is believed to require the involvement of the medial temporal lobe (MTL). In this study, the hypothesis tested was that this involvement is best appreciated by the pattern of MTL functional connectivity with other brain areas. In a sensory learning paradigm, human subjects were classified as AWARE or UNAWARE, on the basis of whether they noted that one of two tones predicted a visual event. Only AWARE subjects acquired and reversed a differential response to the tones. However, learned facilitation was evident in both groups. MTL activity, indexed by blood flow changes measured with positron emission tomography, was correlated with facilitation in both groups but in opposite directions (greater MTL activity was related to less facilitation in AWARE subjects but more facilitation in UNAWARE subjects). Discrimination and reversal in AWARE subjects involved anterior medial, inferior prefrontal, and lateral occipital cortices. Furthermore, unique regional patterns of MTL functional connectivity were observed: AWARE subjects engaged dorsolateral prefrontal and lateral occipital cortices, whereas UNAWARE subjects showed a more spatially restricted network involving contralateral MTL regions and the thalamus. In the AWARE group, the MTL functional connectivity pattern overlapped with regions associated with facilitation and discrimination, but in UNAWARE subjects, the MTL pattern was related only to facilitation. These results suggest that the MTL and functional connected regions, including dorsolateral and medial prefrontal cortex, acted to link facilitation and discrimination patterns in AWARE subjects. Thus, the contribution of the MTL to learning and awareness is shaped by the pattern of interregional interactions, the neural context.

Acoustic Stimulation↗