Tuller, Betty

The current study uses a diabetic rat model to measure the effects of pulsatile
versus continuous insulin delivery on IRS-2 in the liver. The purpose is to determine if
pulsatile, compared with continuous, insulin delivery leads to reduced insulin resistance
in diabetic rats. Insulin signaling in the liver is mediated primarily through IRS-2 and
tissue responsiveness to insulin may be detected by monitoring the lRS-2 signaling
pathway. Western blots were performed to measure IRS-2 protein levels for each
delivery condition and treatment day. Results revealed that overall, the pulsatile insulin
delivery method showed a significant increase in IRS-2 levels over the continuous insulin
delivery method by treatment day 5. These findings imply that the pulsatile delivery
method, over a period of time, triggers more insulin receptor action. Conversely, the
results of the continuous delivery system show a decrease in IRS-2 levels as the number
of doses of insulin increased.

This experiment investigated the role of sentence meaning in auditory language comprehension. Tokens from a GOAT-COAT speech voicing continuum were embedded in carrier sentences that were biased toward either a "goat" or "coat" interpretation and presented to subjects for a word identification task. The identification function showed a boundary shift in favor of the biased context, and an interaction localized to the ambiguous boundary region. Response times were largest in the boundary region and the interaction between the two factors was localized to the boundary region and the voiced endpoint. There was also a response time advantage for context consistent responses specifically in the boundary region. These results and those of earlier research (Connine, 1987; Connine & Clifton, 1987) are described in terms of interactive activation of potential response categories by acoustic parameter and sentence context.

The convention of representing pitch distances within a circular symmetric scheme has a long history. Perception of the pitch pattern of pairs of circular tones (Shepard, 1964) was examined in three different orderings of the comparison tone. Consistent with previous reports, when tone pairs were randomized the pitch was equally likely to be judged as ascending or descending as the frequency change neared the half-octave. In the ordered conditions, the pitch boundary was sensitive to the direction of frequency change such that hysteresis effects were observed for all subjects. A matrix was constructed of directional pitch judgments to all pairs of circular tones presented randomly. Perception of selected pairs was then predicted on the basis of map region consistency. The results indicate that perception of pitch change is influenced not only by the frequency difference between members of a pair, but also by preceding percepts.

Facial recognition memory is a specialized system in the human brain, with an effect of familiarity playing a role in the brain activations involved. Previous studies examining the familiar face processing system have used college-aged subjects. However, memory disorders, like those associated with Alzheimer's disease, typically affect adults over sixty. In an attempt to reveal possible differences between young and older adults', two different age groups were subjected to fMRI analysis while viewing face images with varying familiarity (family, famous and novel). The result showed a significant difference in activations for various cortical areas including the precuneus, cingulate cortex, and fusiform gyrus. Among the differences, an overall trend of greater activation in the left hemisphere for younger subjects compared to the older group was revealed. The results have implications for the study of memory disorders afflicting older adults, like Alzheimer's disease.

This study investigated the interaction of acoustic and semantic information for phoneme categorization during sentence comprehension. Voice onset time (VOT) was manipulated to form a goat-to-coat voicing continuum; target stimuli from this continuum were embedded in sentences biased toward `goat' or `coat'. Sentences were presented in conjunction with three distinct experimental tasks and several temporal positions. Experiment 1A used a cross-modal identification task (Borsky, Tuller, and Shapiro, 1998) to cue stimulus identification at the target; the results showed sentence context biases on identifications and sentence context congruency effects on response times for mid-range stimuli. Experiment 1B used a cross-modal identification task 450 ms after the target; results showed sentence biases on identifications that extended to the endpoints and no sentence context congruency effects on response times. Experiment 2 used a cross-modal interference task (CMI) with the same auditory stimuli. The primary task was listening to the sentences for comprehension; the interference task was a word/non-word decision to an unrelated visual probe that appeared at one of three temporal positions. This was the only task for which no explicit judgments about the identity of the target were required. Response times at the embedded target showed a significant effect of VOT only. The 450 ms later probe position showed a significant VOT x Context interaction; response times were significantly longer for endpoint stimuli when sentence meaning was biased toward the opposite endpoint. These results were interpreted as initially context-independent phonological processing followed by context integration. Experiment 3 used a word-monitoring task; subjects saw the word `goat' or `coat' briefly on a computer screen, then listened to the same sentence stimuli used for the other experiments. The task was to press a button as soon as the monitoring target was heard in the sentence. Results showed that sentence context did not bias identifications. However, response times were significantly longer when sentence context was incongruent with the monitoring target. Taken together, the results of the three distinct tasks support an account of phonological processing in which phoneme categorization is initially independent unless an explicit judgment about the identity of the target is required.