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Temporal Processing (temporal + processing)
Selected AbstractsSeasonal changes in frequency tuning and temporal processing in single neurons in the frog auditory midbrainDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005Jozien BM Goense Abstract Frogs rely on acoustic signaling to detect, discriminate, and localize mates. In the temperate zone, reproduction occurs in the spring, when frogs emerge from hibernation and engage in acoustically guided behaviors. In response to the species mating call, males typically show evoked vocal responses or other territorial behaviors, and females show phonotactic responses. Because of their strong seasonal behavior, it is possible that the frog auditory system also displays seasonal variation, as evidenced in their vocal control system. This hypothesis was tested in male Northern leopard frogs by evaluating the response characteristics of single neurons in the torus semicircularis (TS; a homolog of the inferior colliculus) to a synthetic mating call at different times of the year. We found that TS neurons displayed a seasonal change in frequency tuning and temporal properties. Frequency tuning shifted from a predominance of TS units sensitive to intermediate frequencies (700,1200 Hz) in the winter, to low frequencies (100,600 Hz) in the summer. In winter and early spring, most TS neurons showed poor, or weak, time locking to the envelope of the amplitude-modulated synthetic call, whereas in late spring and early summer the majority of TS neurons showed robust time-locked responses. These seasonal differences indicate that neural coding by auditory midbrain neurons in the Northern leopard frog is subject to seasonal fluctuation. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source] Auditory and speech processing and reading development in Chinese school children: behavioural and ERP evidenceDYSLEXIA, Issue 4 2005Xiangzhi Meng Abstract By measuring behavioural performance and event-related potentials (ERPs) this study investigated the extent to which Chinese school children's reading development is influenced by their skills in auditory, speech, and temporal processing. In Experiment 1, 102 normal school children's performance in pure tone temporal order judgment, tone frequency discrimination, temporal interval discrimination and composite tone pattern discrimination was measured. Results showed that children's auditory processing skills correlated significantly with their reading fluency, phonological awareness, word naming latency, and the number of Chinese characters learned. Regression analyses found that tone temporal order judgment, temporal interval discrimination and composite tone pattern discrimination could account for 32% of variance in phonological awareness. Controlling for the effect of phonological awareness, auditory processing measures still contributed significantly to variance in reading fluency and character naming. In Experiment 2, mismatch negativities (MMN) in event-related brain potentials were recorded from dyslexic children and the matched normal children, while these children listened passively to Chinese syllables and auditory stimuli composed of pure tones. The two groups of children did not differ in MMN to stimuli deviated in pure tone frequency and Chinese lexical tones. But dyslexic children showed smaller MMN to stimuli deviated in initial consonants or vowels of Chinese syllables and to stimuli deviated in temporal information of composite tone patterns. These results suggested that Chinese dyslexic children have deficits in auditory temporal processing as well as in linguistic processing and that auditory and temporal processing is possibly as important to reading development of children in a logographic writing system as in an alphabetic system. Copyright © 2005 John Wiley & Sons, Ltd. [source] Visual, auditory and cross-modal processing of linguistic and nonlinguistic temporal patterns among adult dyslexic readersDYSLEXIA, Issue 2 2005Ann Meyler Abstract This study examined visual, auditory, and cross-modal temporal pattern processing at the nonlinguistic and sublexical linguistic levels, and the relationships between these abilities and decoding skill. The central question addressed whether dyslexic readers are impaired in their perception of timing, as assessed by sensitivity to rhythm. Participants were college-level adult dyslexic and normal readers. The dyslexic adults evidenced generalized impairment in temporal processing: they were less accurate and slower than normal readers when required to detect the temporal gap that differentiated pairs of patterns. Impairment was greatest when processing visual syllables. Temporal pattern processing correlated to decoding ability only among normal readers. It is suggested that high-functioning dyslexics may cope with temporal processing problems by adopting a predominantly holistic, orthographic strategy when decoding. It is proposed that there may be cumulative effects of processing demands from different sources including modality, stimulus complexity, and linguistic demands, and that combinations of these may interact to impact temporal processing ability. Moreover, there may be fundamentally distinct and dissociable temporal processing abilities, each of which may be differently linked developmental dyslexia. Copyright © 2005 John Wiley & Sons, Ltd. [source] Dyslexia and music: measuring musical timing skillsDYSLEXIA, Issue 1 2003Katie Overy Abstract Over the last few decades, a growing amount of research has suggested that dyslexics have particular difficulties with skills involving accurate or rapid timing, including musical timing skills. It has been hypothesised that music training may be able to remediate such timing difficulties, and have a positive effect on fundamental perceptual skills that are important in the development of language and literacy skills (Overy, 2000). In order to explore this hypothesis further, the nature and extent of dyslexics' musical difficulties need to be examined in more detail. In the present study, a collection of musical aptitude tests (MATs) were designed specifically for dyslexic children, in order to distinguish between a variety of musical skills and sub-skills. 15 dyslexic children (age 7,11, mean age 9.0) and 11 control children (age 7,10, mean age 8.9) were tested on the MATs, and their scores were compared. Results showed that the dyslexic group scored higher than the control group on 3 tests of pitch skills (possibly attributable to slightly greater musical experience), but lower than the control group on 7 out of 9 tests of timing skills. Particular difficulties were noted on one of the tests involving rapid temporal processing, in which a subgroup of 5 of the dyslexic children (33%) (mean age 8.4) was found to account for all the significant error. Also, an interesting correlation was found between spelling ability and the skill of tapping out the rhythm of a song, which both involve the skill of syllable segmentation. These results support suggestions that timing is a difficulty area for dyslexic children, and suggest that rhythm skills and rapid skills may need particular attention in any form of musical training with dyslexics. Copyright © 2003 John Wiley & Sons, Ltd. [source] Kindling Limits the Interictal Neuronal Temporal Response Properties in Cat Primary Auditory CortexEPILEPSIA, Issue 2 2005Pamela A. Valentine Summary:,Purpose: The present study examined the effect of electrical kindling on the interictal temporal response properties of single units recorded from primary auditory cortex (AI) of the adult cat. Methods: Cats were permanently implanted with electrodes in AI, kindled twice daily for 40 sessions, and the contralateral AI was subsequently mapped. Kindling stimulation consisted of 1-s trains of biphasic square-wave pulses applied at a frequency of 60 Hz, 100 ,A above the afterdischarge (AD) threshold. The EEG activity was recorded during each kindling session, and the behavioral manifestation was scored. Subsequent to kindling, multiple single-unit responses were recorded under ketamine anesthesia in response to 1-s-long periodic click trains, with click rates between 2 and 64 Hz. Neuronal responses were characterized according to their ability to respond in time-locked fashion to the clicks. Results: Kindling stimulation resulted in progression of the AD characteristics and seizure behavior, with six of 10 kindled cats reaching a fully generalized state. In the fully kindled cats, the best modulation frequencies and limiting following rates for the single-unit responses were significantly lower compared with those of naive and sham controls. Conclusions: Repeated epileptiform activity interferes with temporal processing in cat auditory cortex in the interictal state. This may have implications for people with epileptic foci in auditory-related areas. [source] Computational constraints between retrieving the past and predicting the future, and the CA3-CA1 differentiationHIPPOCAMPUS, Issue 5 2004Alessandro Treves Abstract The differentiation between the CA3 and CA1 fields of the mammalian hippocampus is one of the salient traits that set it apart from the organization of the homologue medial wall in reptiles and birds. CA3 is widely thought to function as an autoassociator, but what do we need CA1 for? Based on evidence for a specific role of CA1 in temporal processing, I have explored the hypothesis that the differentiation between CA3 and CA1 may help solve a computational conflict. The conflict is between pattern completion, or integrating current sensory information on the basis of memory, and prediction, or moving from one pattern to the next in a stored sequence. CA3 would take care of the former, while CA1 would concentrate on the latter. I have found the hypothesis to be only weakly supported by neural network simulations. The conflict indeed exists, but two mechanisms that would relate more directly to a functional CA3-CA1 differentiation were found unable to produce genuine prediction. Instead, a simple mechanism based on firing frequency adaptation in pyramidal cells was found to be sufficient for prediction, with the degree of adaptation as the crucial parameter balancing retrieval with prediction. The differentiation between the architectures of CA3 and CA1 has a minor but significant, and positive, effect on this balance. In particular, for a fixed anticipatory interval in the model, it increases significantly the information content of hippocampal outputs. There may therefore be just a simple quantitative advantage in differentiating the connectivity of the two fields. Moreover, different degrees of adaptation in CA3 and CA1 cells were not found to lead to better performance, further undermining the notion of a functional dissociation. © 2004 Wiley-Liss, Inc. [source] Fat-water separation in dynamic objects using an UNFOLD-like temporal processingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Riad Ababneh PhD Abstract Purpose To separate fat and water signals in dynamic imaging. Because important features may be embedded in fat, and because fat may take part in disease processes, separating fat and water signals may be of great importance in a number of clinical applications. This work aims to achieve such separation at nearly no loss in temporal resolution compared to usual, nonseparated acquisitions. In contrast, the well-known 3-point Dixon method may cause as much as a 3-fold reduction in temporal resolution. Materials and Methods The proposed approach involves modulating the echo time TE from frame to frame, to force fat signals to behave in a conspicuous manner through time, so they can be readily identified and separated from water signals. The strategy is inspired from the "unaliasing by Fourier encoding the overlaps in the temporal direction" (UNFOLD) method, although UNFOLD involves changes in the sampling function rather than TE, and aims at suppressing aliased material rather than fat. Results The method was implemented at 1.5 T and 3 T, on cardiac cine and multiframe steady-state free precession sequences. In addition to phantom results, in vivo results from volunteers are presented. Conclusion Good separation of fat and water signals was achieved in all cases. J. Magn. Reson. Imaging 2010;32:962,970. © 2010 Wiley-Liss, Inc. [source] Neural correlates of deficient response inhibition in mentally disordered violent individualsBEHAVIORAL SCIENCES & THE LAW, Issue 1 2008Ian Barkataki Ph.D. In this study, response inhibition and associated neural activation during a motor inhibition paradigm were investigated in (i) men with antisocial personality disorder (APD) with a history of violence (n,=,14), (ii) men with schizophrenia with a history of violence (n,=,12), (iii) men with schizophrenia without a history of violence (n,=,12), and (iv) healthy control subjects (n,=,14) using functional magnetic resonance imaging (fMRI). At the behavioural level, individuals with schizophrenia showed impaired performance across all conditions, whereas an increased error rate was seen in the APD group only during the conditions requiring inhibition. At the neural level, both violent groups showed reduced thalamic activity, compared with controls, in association with modulation of inhibition by task demands. In addition, the violent schizophrenia group, compared with controls, showed reduced activity in the caudate nucleus during the condition requiring inhibition. It is concluded that violence may not be specifically associated with impaired voluntary inhibition in schizophrenia but this is likely in APD. Reduced thalamic function, perhaps due to its known association with sensorimotor disturbances, is implicated in violent behaviour across both disorders. In addition, caudate dysfunction may contribute, given its role in timing and temporal processing as well as suppression of motor actions, to deficient inhibition and violent behaviour in schizophrenia. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||