Biomedical subjects

Peter C Hansen

Publications and source records attributed to Peter C Hansen.

6 recordsLinked to original sources

PubMed2005

Color of scents: chromatic stimuli modulate odor responses in the human brain.

Color has a profound effect on the perception of odors. For example, strawberry-flavored drinks smell more pleasant when colored red than green and descriptions of the "nose" of a wine are dramatically influenced by its color. Using functional magnetic resonance imaging, we demonstrate a neurophysiological correlate of these cross-modal visual influences on olfactory perception. Subjects were scanned while exposed either to odors or colors in isolation or to color-odor combinations that were rated on the basis of how well they were perceived to match. Activity in caudal regions of the orbitofrontal cortex and in the insular cortex increased progressively with the perceived congruency of the odor-color pairs. These findings demonstrate the neuronal correlates of olfactory response modulation by color cues in brain areas previously identified as encoding the hedonic value of smells.

Adult↗

PubMed2004

Visual word recognition: the first half second.

We used magnetoencephalography (MEG) to map the spatiotemporal evolution of cortical activity for visual word recognition. We show that for five-letter words, activity in the left hemisphere (LH) fusiform gyrus expands systematically in both the posterior-anterior and medial-lateral directions over the course of the first 500 ms after stimulus presentation. Contrary to what would be expected from cognitive models and hemodynamic studies, the component of this activity that spatially coincides with the visual word form area (VWFA) is not active until around 200 ms post-stimulus, and critically, this activity is preceded by and co-active with activity in parts of the inferior frontal gyrus (IFG, BA44/6). The spread of activity in the VWFA for words does not appear in isolation but is co-active in parallel with spread of activity in anterior middle temporal gyrus (aMTG, BA 21 and 38), posterior middle temporal gyrus (pMTG, BA37/39), and IFG.

Adult↗

PubMed2004

M-cell deficit and reading disability: a preliminary study of the effects of temporal vision-processing therapy.

BACKGROUND: This study examines the following questions: In moderately disabled readers, will temporal vision-processing therapy procedures that benefit reading comprehension, visual attention, and oculomotor skills ameliorate M-cell processing deficits as measured with coherent motion threshold testing? And will the results show a corresponding improvement in oral reading and verbal skills? METHOD: A sample of 16 moderately disabled readers, evaluated in a study completed 6 months earlier, were retested with another form of the Gates-MacGinitie Reading Test. Each participant was additionally tested for coherent motion, oral reading, and word attack skills. During the succeeding 6 months, fifteen 45-minute therapy sessions were administered once a week (as the school schedule permitted). After completing 15 therapy sessions, the initial testing procedures were repeated. RESULTS: All four variables--namely, Gates-MacGinitie Reading Test, Coherent Motion Threshold Test, Gray Oral Reading Test, and Woodcock-Johnson Word Attack Test--revealed significant improvements after temporal vision therapy. Half of the 16 participants improved 2 or more years in reading comprehension, compared to no significant mean difference following the 6-month "control period" before the onset of therapy. CONCLUSIONS: This research supports the value of rendering temporal vision therapy to children identified as moderately reading disabled (RD). The diagnostic procedures and the dynamic therapeutic techniques discussed in this article have not been previously used for the specific purpose of ameliorating an M-cell deficit. Improved temporal visual-processing skills and enhanced visual motion discrimination appear to have a salutary effect on magnocellular processing and reading comprehension in RD children with M-cell deficits.

Child↗

PubMed2003

The perception of "sine-wave speech" by adults with developmental dyslexia.

Numerous studies have shown that, as a group, children or adults with developmental dyslexia perceive isolated syllables or words abnormally. Continuous speech containing reduced acoustic information also might prove perceptually difficult to such listeners. They might, however, exploit the intact syntactic and semantic features present in whole utterances, thereby compensating fully for impaired speech perception. "Sine-wave speech" sentences afford a test of these competing possibilities. The sentences contain only 4 frequency-modulated sine waves, lacking many acoustic cues present in natural speech. Adults with and without dyslexia were asked to orally reproduce 9 sine-wave utterances, each occurring in 4 immediately successive trials. Participants with dyslexia reported fewer words than did control listeners. Practice, phonological contrasts, and word position affected both groups similarly. Comprehension of sine-wave sentences seems impaired in many, but not all, adults with dyslexia. A reduced auditory memory capacity may contribute to this deficit.

Adult↗

PubMed2003

Coherent motion threshold measurements for M-cell deficit differ for above- and below-average readers.

BACKGROUND: Research during the past 20 years has influenced the management of diagnosis and treatment of children identified as having learning-related vision problems. The intent of this study is to determine whether coherent motion threshold testing can distinguish better-than-average non-disabled (ND) readers from those who are moderately reading disabled (RD) among sixth-grade students. METHOD: A sample of 23 better-than-average non-disabled readers (> or = 80th percentile) and 27 moderately disabled readers (< or = 32nd percentile) were identified using a standardized reading comprehension test. Each participant was tested for coherent motion threshold. Previous psychophysical and fMRI research with adults suggests that coherent motion threshold is a valid measure of magnocellular (M-cell) integrity. RESULTS: The average of two coherent motion threshold trials was significantly greater for moderately reading disabled subjects than for above-average readers (p < 0.01). The mean threshold percentage of dots required to observe lateral motion was 9.2% for moderately reading disabled readers and 4.6% for superior readers (p = 0.001). CONCLUSION: The outcome of this preliminary study provides an efficient procedure to identify sixth-grade students whose reading disability may be associated with an M-cell deficit. Our previous investigations involving visual processing, visual attention, and oculomotor therapy have resulted in significant improvements in reading comprehension, visual attention, and eye movements. It remains to be demonstrated whether vision therapy has an impact on the M-cell deficit, as measured with coherent motion threshold testing for moderately disabled readers.

Case-Control Studies↗

PubMedDate not supplied

On the relationship between dynamic visual and auditory processing and literacy skills; results from a large primary-school study.

Three hundred and fifty randomly selected primary school children completed a psychometric and psychophysical test battery to ascertain relationships between reading ability and sensitivity to dynamic visual and auditory stimuli. The first analysis examined whether sensitivity to visual coherent motion and auditory frequency resolution differed between groups of children with different literacy and cognitive skills. For both tasks, a main effect of literacy group was found in the absence of a main effect for intelligence or an interaction between these factors. To assess the potential confounding effects of attention, a second analysis of the frequency discrimination data was conducted with performance on catch trials entered as a covariate. Significant effects for both the covariate and literacy skill was found, but again there was no main effect of intelligence, nor was there an interaction between intelligence and literacy skill. Regression analyses were conducted to determine the magnitude of the relationship between sensory and literacy skills in the entire sample. Both visual motion sensitivity and auditory sensitivity to frequency differences were robust predictors of children's literacy skills and their orthographic and phonological skills.

Auditory Perception↗