Biomedical subjects

Heather Bortfeld

Publications and source records attributed to Heather Bortfeld.

4 recordsLinked to original sources

PubMed2006

Assessing infants' cortical response to speech using near-infrared spectroscopy.

Sensitivity to spoken language is an integral part of infants' formative development, yet relatively little is known about the neural mechanisms that underlie the emerging ability to perceive and process speech. This is in large part because there are a limited number of non-invasive techniques available to measure brain functioning in human infants. Near-infrared spectroscopy (NIRS), an optical imaging technique that estimates changes in neuronal activity by measuring changes in total hemoglobin concentration and oxygenation, may be a viable procedure for assessing the relation between speech processing and brain function in human infants. While auditory processing data have been gathered from newborn and preterm infants using NIRS, such data have not been collected from older infants. Many behavioral measures used to establish linguistic sensitivity in this population are accompanied by visual stimuli; however, it is unclear how coupling of auditory and visual stimuli influences neural processing. Here we studied cortical activity in infants aged 6-9 months, as measured by NIRS, during exposure to linguistic stimuli paired with visual stimuli and compared this to the activity observed in the same regions during exposure to visual stimuli alone. Results dissociate infants' hemodynamic responses to multimodal and unimodal stimuli, demonstrating the utility of NIRS for studying perceptual development in infants. In particular, these findings support the use of NIRS to study the neurobiology of language development in older infants, a task that is difficult to accomplish without the use of attention-getting visual stimuli.

Female↗

PubMed2005

Mommy and me: familiar names help launch babies into speech-stream segmentation.

How do infants find the words in the tangle of speech that confronts them? The present study shows that by as early as 6 months of age, infants can already exploit highly familiar words-including, but not limited to, their own names-to segment and recognize adjoining, previously unfamiliar words from fluent speech. The head-turn preference procedure was used to familiarize babies with short passages in which a novel word was preceded by a familiar or a novel name. At test, babies recognized the word that followed the familiar name, but not the word that followed the novel name. This is the youngest age at which infants have been shown capable of segmenting fluent speech. Young infants have a powerful aid available to them for cracking the speech code. Their emerging familiarity with particular words, such as their own and other people's names, can provide initial anchors in the speech stream.

Attention↗

PubMed2003

Comprehending idioms cross-linguistically.

Speakers of three different languages (English, Latvian, and Mandarin) rated sets of idioms from their language for the analyzability of the relationship between each phrase's literal and figurative meaning. For each language, subsets of idioms were selected based on these ratings. Latvian and Mandarin idioms were literally translated into English. Across three experiments, people classified idioms from the three languages according to their figurative meanings. Response times and error rates indicate that participants were able to interpret unfamiliar (e.g., other languages') idioms depending largely on the degree to which they were analyzable, and that different forms of processing were used both within and between languages depending on this analyzability. Results support arguments for a continuum of analyzability (Bortfeld & McGlone, 2001), along which figurative speech ranges from reflecting general conceptual structures to specific cultural and historical references.

Cognition↗

PubMedDate not supplied

Using near-infrared spectroscopy to assess neural activation during object processing in infants.

The capacity to represent the world in terms of numerically distinct objects (i.e., object individuation) is a milestone in early cognitive development and forms the foundation for more complex thought and behavior. Over the past 10 to 15 yr, infant researchers have expended a great deal of effort to identify the origins and development of this capacity. In contrast, relatively little is known about the neural mechanisms that underlie the ability to individuate objects, in large part because there are a limited number of noninvasive techniques available to measure brain functioning in human infants. Recent research suggests that near-IR spectroscopy (NIRS), an optical imaging technique that uses relative changes in total hemoglobin concentration and oxygenation as an indicator of neural activation, may be a viable procedure for assessing the relation between object processing and brain function in human infants. We examine the extent to which increased neural activation, as measured by NIRS, could be observed in two neural areas known to be involved in object processing, the primary visual cortex and the inferior temporal cortex, during an object processing task. Infants aged 6.5 months are presented with a visual event in which two featurally distinct objects emerge successively to opposite sides of an occluder and neuroimaging data are collected. As predicted, increased neural activation is observed in both the primary visual and inferior cortex during the visual event, suggesting that these neural areas support object processing in the young infant. The outcome has important implications for research in cognitive development, developmental neuroscience, and optical imaging.

Cerebrovascular Circulation↗