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Sophie K Scott

Publications and source records attributed to Sophie K Scott.

At least 19 recordsLinked to original sources
PubMed2006

Positive emotions preferentially engage an auditory-motor "mirror" system.

Social interaction relies on the ability to react to communication signals. Although cortical sensory-motor "mirror" networks are thought to play a key role in visual aspects of primate communication, evidence for a similar generic role for auditory-motor interaction in primate nonverbal communication is lacking. We demonstrate that a network of human premotor cortical regions activated during facial movement is also involved in auditory processing of affective nonverbal vocalizations. Within this auditory-motor mirror network, distinct functional subsystems respond preferentially to emotional valence and arousal properties of heard vocalizations. Positive emotional valence enhanced activation in a left posterior inferior frontal region involved in representation of prototypic actions, whereas increasing arousal enhanced activation in presupplementary motor area cortex involved in higher-order motor control. Our findings demonstrate that listening to nonverbal vocalizations can automatically engage preparation of responsive orofacial gestures, an effect that is greatest for positive-valence and high-arousal emotions. The automatic engagement of responsive orofacial gestures by emotional vocalizations suggests that auditory-motor interactions provide a fundamental mechanism for mirroring the emotional states of others during primate social behavior. Motor facilitation by positive vocal emotions suggests a basic neural mechanism for establishing cohesive bonds within primate social groups.

Acoustic Stimulation↗
PubMed2006

What is the relationship between phonological short-term memory and speech processing?

Traditionally, models of speech comprehension and production do not depend on concepts and processes from the phonological short-term memory (pSTM) literature. Likewise, in working memory research, pSTM is considered to be a language-independent system that facilitates language acquisition rather than speech processing per se. We discuss couplings between pSTM, speech perception and speech production, and we propose that pSTM arises from the cycling of information between two phonological buffers, one involved in speech perception and one in speech production. We discuss the specific role of these processes in speech processing, and argue that models of speech perception and production, and our understanding of their neural bases, will benefit from incorporating them.

Attention↗
PubMed2006

Converging language streams in the human temporal lobe.

There is general agreement that, after initial processing in unimodal sensory cortex, the processing pathways for spoken and written language converge to access verbal meaning. However, the existing literature provides conflicting accounts of the cortical location of this convergence. Most aphasic stroke studies localize verbal comprehension to posterior temporal and inferior parietal cortex (Wernicke's area), whereas evidence from focal cortical neurodegenerative syndromes instead implicates anterior temporal cortex. Previous functional imaging studies in normal subjects have failed to reconcile these opposing positions. Using a functional imaging paradigm in normal subjects that used spoken and written narratives and multiple baselines, we demonstrated common activation during implicit comprehension of spoken and written language in inferior and lateral regions of the left anterior temporal cortex and at the junction of temporal, occipital, and parietal cortex. These results indicate that verbal comprehension uses unimodal processing streams that converge in both anterior and posterior heteromodal cortical regions in the left temporal lobe.

Adult↗
PubMed2006

The neural correlates of declining performance with age: evidence for age-related changes in cognitive control.

The neural system involved in cognitive control includes the anterior cingulate cortex (ACC) and the lateral prefrontal cortex (PFC). Neural activity within these structures is sensitive to aging. We investigated the hypothesis that decline in performance with age results in increased cognitive control, as indexed by greater activity within the ACC and lateral PFC. Using positron emission tomography we measured neural activity during a range of verbal decision-making tasks in 16 subjects aged 37-83 years. Conditions were separated behaviorally on the basis of their sensitivity to aging. This allowed the comparison of age-dependent and age-independent conditions, revealing the neural correlates of age-dependent decline in performance. We then modeled the relationship between age, decision type, performance, and frontal lobe activity. ACC activity was independently predicted by age and decision-making accuracy, indicating that in older individuals ACC response is more sensitive to declining performance. We also found strong functional connectivity between the ACC and lateral PFC and observed that activation of the lateral PFC was qualitatively different over time in different age groups. Thus, the ACC and lateral PFC show distinct responses to age-related decline in decision-making performance. This suggests that greater cognitive control is employed as individuals age and their performance declines.

Adult↗
PubMed2006

Neural correlates of intelligibility in speech investigated with noise vocoded speech--a positron emission tomography study.

Functional imaging studies of speech perception in the human brain have identified a key role for auditory association areas in the temporal lobes (bilateral superior temporal gyri and sulci) in the perceptual processing of the speech signal. This is extended to suggest some functional specialization within this bilateral system, with a particular role for the left anterior superior temporal sulcus (STS) in processing intelligible speech. In the current study, noise-vocoded speech was used to vary the intelligibility of speech parametrically. This replicated the finding of a selective response to intelligibility in speech in the left anterior superior temporal sulcus, in contrast to the posterior superior temporal sulcus, which showed a response profile insensitive to the degree of intelligibility. These results are related to theories of functional organization in the human auditory system, which have indicated that there are separate processing streams, with different functional roles, running anterior and posterior to primary auditory cortex. Specifically, it is suggested that an anterior stream processing intelligibility can be distinguished from a posterior stream associated with transient representations, important in spoken repetition and working memory.

Acoustic Stimulation↗
PubMed2005

Now you hear it, now you don't: transient traces of consonants and their nonspeech analogues in the human brain.

The apparently effortless identification of speech is one of the human auditory cortex' finest and least understood functions. This is partly due to difficulties to tease apart effects of acoustic and phonetic attributes of speech sounds. Here we present evidence from magnetic source imaging that the auditory cortex represents speech sounds (such as [g] and [t]) in a topographically orderly fashion that is based on phonetic features. Moreover, this mapping is dependent on intelligibility. Only when consonants are identifiable as members of a native speech sound category is topographical spreading out in the auditory cortex observed. Feature separation in the cortex also varies with a listener's ability to tell these easy-to-confuse consonants from one another. This is the first demonstration that speech-specific maps of features can be identified in human auditory cortex, and it will further help us to delineate speech processing pathways based on models from functional neuroimaging and non-human primates.

Adult↗
PubMed2005

Lexical retrieval constrained by sound structure: the role of the left inferior frontal gyrus.

Positron emission tomography was used to investigate two competing hypotheses about the role of the left inferior frontal gyrus (IFG) in word generation. One proposes a domain-specific organization, with neural activation dependent on the type of information being processed, i.e., surface sound structure or semantic. The other proposes a process-specific organization, with activation dependent on processing demands, such as the amount of selection needed to decide between competing lexical alternatives. In a novel word retrieval task, word reconstruction (WR), subjects generated real words from heard non-words by the substitution of either a vowel or consonant. Both types of lexical retrieval, informed by sound structure alone, produced activation within anterior and posterior left IFG regions. Within these regions there was greater activity for consonant WR, which is more difficult and imposes greater processing demands. These results support a process-specific organization of the anterior left IFG.

Adult↗
PubMed2005

Auditory processing--speech, space and auditory objects.

There have been recent developments in our understanding of the auditory neuroscience of non-human primates that, to a certain extent, can be integrated with findings from human functional neuroimaging studies. This framework can be used to consider the cortical basis of complex sound processing in humans, including implications for speech perception, spatial auditory processing and auditory scene segregation.

Acoustic Stimulation↗
PubMed2004

Retrieving meaning after temporal lobe infarction: the role of the basal language area.

During speech comprehension the auditory association cortex in the superior temporal cortex is involved in perceptual analysis of the speech signal, whereas the basal language area in the inferior temporal cortex mediates access to word meaning. Disruption of the interaction between the superior and inferior temporal cortices is one factor that may determine recovery from aphasic stroke. We used positron emission tomography to investigate semantic processing within inferior temporal cortex in control subjects and after infarction involving the superior temporal cortex. In the control group, semantic decision making on clear speech activated both anterior fusiform gyri. Chronic aphasic patients were impaired at the task and demonstrated reduced activation within the left anterior fusiform gyrus. A similar pattern of impaired performance and reduced left anterior fusiform gyrus activation was observed when control subjects heard perceptually degraded speech. Performance in both groups predicted activity in the right anterior fusiform gyrus and the temporal poles, where accuracy linearly correlated with activity. These results demonstrate that the function of the basal language area is sensitive to changes in the quality of perceptual input. In addition, different profiles of response observed in each hemisphere suggest distinct contributions of both left and right inferior temporal cortices to the semantic processing of speech.

Adult↗
PubMed2004

Auditory processing skills and phonological representation in dyslexic children.

It is now well-established that there is a causal connection between children's phonological skills and their acquisition of reading and spelling. Here we study low-level auditory processes that may underpin the development of phonological representations in children. Dyslexic and control children were given a battery of phonological tasks, reading and spelling tasks and auditory processing tasks. Potential relations between deficits in dyslexic performance in the auditory processing tasks and phonological awareness were explored. It was found that individual differences in auditory tasks requiring amplitude envelope rise time processing explained significant variance in phonological processing. It is argued that developmentally, amplitude envelope cues may be primary in establishing well-specified phonological representations, as these cues should yield important rhythmic and syllable-level information about speech.

Anomia↗
PubMed2004

The neural representation of concrete nouns: what's right and what's left?

In a recent paper, Fiebach and Friederici review the literature in the functional imaging of abstract and concrete nouns, and present an fMRI study. They conclude that (a) there is no evidence for a right hemispheric imaginal system that is specifically associated with concrete nouns, and (b) there is evidence supporting aspects of both the context-availability and dual-coding accounts of noun processing. I relate this result to aspects of process and representation, and the anatomy of the ventral temporal lobe.

Decision Making↗
PubMed2004

Cortical processing of complex sound: a way forward?

The organization of the cortical auditory system remains controversial. In particular, the extent to which there is regional specialization in the cortical processing of complex sound is unclear. Here, we ask whether we are currently asking the right questions of auditory cortex, or using the appropriate techniques to do so. A key factor that will promote such understanding in the future will be increasing dialogue between workers using electrophysiological recording methods to assess the response properties of single neurons and those using imaging techniques to map regional organization. In the future, further insights will be obtained by efforts to test hypotheses developed on the basis of one approach by the use of the other. Imaging can tell the neurophysiologists where to look, and work on single neurons can constrain network models based on imaging. There is a crucial need for better understanding of the anatomy of the auditory cortex in different species and for comparative studies that will underpin both approaches.

Acoustic Stimulation↗
PubMed2004

Monitoring and the controlled processing of meaning: distinct prefrontal systems.

Distinct prefrontal regions are specialized for the controlled processing of semantic information. We have dissociated components of this system used in semantic decision-making across different perceptual conditions. Nineteen subjects were presented with auditory word sequences, on which they made semantic or syllabic decisions, while neural activity was measured using PET. Contrasting the semantic with syllabic tasks, there was activation within left rostral prefrontal cortex (RPFC) when the stimuli were presented as clear speech, reducing when the stimuli were presented in acoustically degraded form. In contrast, activation of the right dorsolateral prefrontal cortex (DLPFC) was observed with the degraded stimuli, an effect that inversely correlated with accuracy on the task. We have thus demonstrated two prefrontal systems where activity is differentially modulated by the "quality" of information held in working memory. This dissociation is likely to represent an alteration in the type of cognitive operations employed during task performance, where left RPFC is activated during extensive semantic elaboration and right DLPFC is recruited as the monitoring demands, associated with items held in working memory, increase. The function of these separate systems is integrated during the performance of verbal problem-solving tasks although they are differentially sensitive to stimulus degradation.

Adult↗
PubMed2004

A positron emission tomography study of the neural basis of informational and energetic masking effects in speech perception.

Positron emission tomography (PET) was used to investigate the neural basis of the comprehension of speech in unmodulated noise ("energetic" masking, dominated by effects at the auditory periphery), and when presented with another speaker ("informational" masking, dominated by more central effects). Each type of signal was presented at four different signal-to-noise ratios (SNRs) (+3, 0, -3, -6 dB for the speech-in-speech, +6, +3, 0, -3 dB for the speech-in-noise), with listeners instructed to listen for meaning to the target speaker. Consistent with behavioral studies, there was SNR-dependent activation associated with the comprehension of speech in noise, with no SNR-dependent activity for the comprehension of speech-in-speech (at low or negative SNRs). There was, in addition, activation in bilateral superior temporal gyri which was associated with the informational masking condition. The extent to which this activation of classical "speech" areas of the temporal lobes might delineate the neural basis of the informational masking is considered, as is the relationship of these findings to the interfering effects of unattended speech and sound on more explicit working memory tasks. This study is a novel demonstration of candidate neural systems involved in the perception of speech in noisy environments, and of the processing of multiple speakers in the dorso-lateral temporal lobes.

Acoustic Stimulation↗
PubMed2003

The role of the rostral frontal cortex (area 10) in prospective memory: a lateral versus medial dissociation.

Using the H(2)(15)O PET method, we investigated whether previous findings of regional cerebral blood flow (rCBF) changes in the polar and superior rostral aspects of the frontal lobes (principally Brodmann's area (BA) 10) during prospective memory (PM) paradigms (i.e. those involving carrying out an intended action after a delay) can be attributed merely to the greater difficulty of such tasks over the baseline conditions typically employed. Three different tasks were administered under four conditions: baseline simple RT; attention-demanding ongoing task only; ongoing task plus a delayed intention (unpracticed); ongoing task plus delayed intention (practiced). Under prospective memory conditions, we found significant rCBF decreases in the superior medial aspects of the rostral prefrontal cortex (BA 10) relative to the baseline or ongoing task only conditions. However more lateral aspects of area 10 (plus the medio-dorsal thalamus) showed the opposite pattern, with rCBF increases in the prospective memory conditions relative to the other conditions. These patterns were broadly replicated over all three tasks. Since both the medial and lateral rostral regions showed: (a) instances where rCBF was lower during a more effortful condition (as estimated by increased RTs and error rates) than in a less effortful one; and (b) there was no correlation between rCBF and RT durations or number of errors in these regions, a simple task difficulty explanation of the rCBF changes in the rostral aspects of the frontal lobes during prospective memory tasks is rejected. Instead, the favoured explanation concentrates upon the particular processing demands made by these situations irrespective of the precise stimuli used or the exact nature of the intention. Moreover, the results suggest different roles for medial and lateral rostral prefrontal cortex, with the former involved in suppressing internally-generated thought, and the latter in maintaining it.

Adult↗
PubMed2003

The neuroanatomical and functional organization of speech perception.

A striking property of speech perception is its resilience in the face of acoustic variability (among speech sounds produced by different speakers at different times, for example). The robustness of speech perception might, in part, result from multiple, complementary representations of the input, which operate in both acoustic-phonetic feature-based and articulatory-gestural domains. Recent studies of the anatomical and functional organization of the non-human primate auditory cortical system point to multiple, parallel, hierarchically organized processing pathways that involve the temporal, parietal and frontal cortices. Functional neuroimaging evidence indicates that a similar organization might underlie speech perception in humans. These parallel, hierarchical processing 'streams', both within and across hemispheres, might operate on distinguishable, complementary types of representations and subserve complementary types of processing. Two long-opposing views of speech perception have posited a basis either in acoustic feature processing or in gestural motor processing; the view put forward here might help reconcile these positions.

Acoustic Stimulation↗
PubMed2003

Going beyond the information given: a neural system supporting semantic interpretation.

Relating the meaning of a word to the context in which it is encountered is central to comprehension. We investigated the neural basis of this process. Subjects made decisions based on a semantic property of single nouns. The lack of sentence context created ambiguity, as nouns may have several, unrelated semantic identities. Contrasted with unambiguous decisions about each noun's sound structure, the semantic task resulted in activity in the left superior frontal gyrus (SFG), activity that was dependent on choice reaction time. This identified the left SFG as an executive component of a distributed cognitive system that relates a word's meaning to its semantic context to facilitate comprehension.

Adult↗