An fMRI study of temporal sequencing of motor regulation guided by an auditory cue—a comparison with visual guidance

The neuronal system to process and transfer auditory information to the higher motor areas was investigated using fMRI. Two different types of internal modulation of auditory pacing (1 Hz) were combined to design a 2×2 condition experiment, and the activation was compared with that under a visual guidance. The bilateral anterior portion of the BA22 (ant-BA22) and the left BA41/42 were more extensively activated by the combined modulation condition under the auditory cue than that under the visual cue. Among the four auditory conditions with or without the two types of internal modulation, the activation in the ant-BA22 was augmented only on the left side by the combined modulation condition. The left ant-BA22 may be especially involved in integrating the external auditory cue with internal modulation, while the activation on the right side did not depend on the complexity. The role of the left BA41/42 in motor regulation may be more specific to the processing of an auditory cue than that on the right side. These two areas in the left temporal lobe may be organized as a subsystem to handle the timing of complex movements under auditory cues, while the higher motor areas in the frontal lobe support both sensory modalities for the cue. This architecture may be considered as ‘audio-motor control’, which is similar to the visuo-motor control of the front-parietal network.     

The role of regional heterogeneity in age-related differences in functional hemispheric asymmetry: an fMRI study

Neuroimaging literature has documented age-related hemispheric asymmetry reduction in frontal regions during task performances. As most studies employed working memory paradigms, it is therefore less clear if this pattern of neural reorganization is constrained by working memory processes or it would also emerge in other cognitive domains which are predominantly lateralized. Using blocked functional magnetic resonance imaging (fMRI), the present study used a homophone judgment task and a line judgment task to investigate age-related differences in functional hemispheric asymmetry in language and visuospatial processing respectively. Young and older adults achieved similar task accuracy although older adults required a significantly longer time. Age-related functional hemispheric asymmetry reduction was found only in dorsal inferior frontal gyrus and was associated with better performance when the homophone condition was contrasted against fixation, and not line condition. Our data thus highlights the importance of considering regional heterogeneity of aging effects together with general age-related cognitive processes.     

The influence of babbling patterns on the processing of speech

This study compared the preference of 27 British English- and 26 Welsh-learning infants for nonwords featuring consonants that occur with equal frequency in the input but that are produced either with equal frequency (Welsh) or with differing frequency (British English) in infant vocalizations. For the English infants a significant difference in looking times was related to the extent of production of the nonword consonants. The Welsh infants, who showed no production preference for either consonant, exhibited no such influence of production patterns on their response to the nonwords. The results are consistent with a previous study that suggested that pre-linguistic babbling helps shape the processing of input speech, serving as an articulatory filter that selectively makes production patterns more salient in the input.     

Distinguishing novelty and familiarity effects in infant preference procedures

This paper considers possible problems researchers might face when interpreting the results of studies that employ variants of the preference procedure. Infants show a tendency to shift their preference from familiar to novel stimuli with increasing exposure to the familiar stimulus, a behaviour that is exploited by the habituation paradigm. This change in attentional preference with exposure leads us to suggest that researchers interested in infants' pre‐experimental or spontaneous preferences should beware of the potentially confounding effects of exposing infants to familiarization trials prior to employing the preference procedure. The notion that infant attentional preference is dynamic also calls into question the use of the direction of post‐familiarization preference per se when interpreting the knowledge or strategies available to infants. We look into the results of a cross‐modal word learning study to show how the interpretation of results may be difficult when infants exhibit a significant preference in an unexpected direction. As a possible solution to this problem we propose that significant preferences in both directions should be sought at multiple intervals over time. Copyright © 2004 John Wiley & Sons, Ltd.     

Association of maternal smoking during pregnancy and infant neurobehavioral status

The association of maternal smoking during pregnancy with neurobehavioral status was examined in 344 Japanese infants. Based on a questionnaire, their mothers were classified into three groups, Nonsmokers, Exsmokers, and Smokers. The Neonatal Behavioral Assessment Scale was administered three days after birth. Among the three groups, on the seven clusters and their 28 behavioral subscales there were no significant differences. The infants of Smokers had lower scores than those of Exsmokers and Nonsmokers on two behavioral items, general tone and peak of excitement. General tone remained significant after adjustment for covariates.     

Critical role of the 65-kDa isoform of glutamic acid decarboxylase in consolidation and generalization of Pavlovian fear memory

Evidence suggests that plasticity of the amygdalar and hippocampal GABAergic system is critical for fear memory formation. In this study we investigated in wild-type and genetically manipulated mice the role of the activity-dependent 65-kDa isozyme of glutamic acid decarboxylase (GAD65) in the consolidation and generalization of conditioned fear. First, we demonstrate a transient reduction of GAD65 gene expression in the dorsal hippocampus (6 h post training) and in the basolateral complex of the amygdala (24 h post training) during distinct phases of fear memory consolidation. Second, we show that targeted ablation of the GAD65 gene in Gad65(-/-) mice results in a pronounced context-independent, intramodal generalization of auditory fear memory during long-term (24 h or 14 d) but not short-term (30 min) memory retrieval. The temporal specificity of both gene regulation and memory deficits in Gad65 mutant mice suggests that GAD65-mediated GABA synthesis is critical for the consolidation of stimulus-specific fear memory. This function appears to involve a modulation of neural activity patterns in the amygdalo-hippocampal pathway as indicated by a reduction in theta frequency synchronization between the amygdala and hippocampus of Gad65(-/-) mice during the expression of generalized fear memory.