Katherine L. (Katie) Wheat | Maastricht University (original) (raw)
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Papers by Katherine L. (Katie) Wheat
This thesis explored a possible role of Broca's area (specifically the pars opercularis of left i... more This thesis explored a possible role of Broca's area (specifically the pars opercularis of left inferior frontal gyrus and neighbouring precentral gyrus; LIFGpo/PCG) in accessing sublexical phonology during visual word recognition. In Experiments 1 to 4, behavioural masked sublexical phonological priming effects were tested during lexical decision and reading aloud in English. No sublexical phonological effects were found during the lexical decision tasks, but significant sublexical phonological priming effects were found during reading aloud. In Experiment 5, masked sublexical phonological priming effects were then tested during a silent reading task using magnetoencephalography. Sublexical phonological priming effects were localised to LIFGpo/PCG within ~200 ms for real word targets and within ~75 ms for nonword targets. This indicates an early sensitivity to sublexical phonological information at LIFGpo/PCG during silent reading of English. In Experiment 6 chronometric functional magnetic resonance imaging guided transcranial magnetic stimulation was used to create focal and transient virtual lesions to LIFGpo/PCG in order to test the hypothesis that the putative early sublexical phonological representations seen at LIFGpo/PCG are functionally necessary for visual word recognition. Dutch participants underwent transcranial magnetic stimulation during reading aloud as compared to picture naming.
Brain and language, 2012
a b s t r a c t Magnetoencephalography (MEG) has shown pseudohomophone priming effects at Broca's... more a b s t r a c t Magnetoencephalography (MEG) has shown pseudohomophone priming effects at Broca's area (specifically pars opercularis of left inferior frontal gyrus and precentral gyrus; LIFGpo/PCG) within 100msofviewingaword.ThisisconsistentwithBroca′sareainvolvementinfastphonologicalaccessduringvisualwordrecognition.Hereweusedonlinetranscranialmagneticstimulation(TMS)toinvestigatewhetherLIFGpo/PCGisnecessaryfor(notjustcorrelatedwith)visualwordrecognitionby100 ms of viewing a word. This is consistent with Broca's area involvement in fast phonological access during visual word recognition. Here we used online transcranial magnetic stimulation (TMS) to investigate whether LIFGpo/PCG is necessary for (not just correlated with) visual word recognition by 100msofviewingaword.ThisisconsistentwithBroca′sareainvolvementinfastphonologicalaccessduringvisualwordrecognition.Hereweusedonlinetranscranialmagneticstimulation(TMS)toinvestigatewhetherLIFGpo/PCGisnecessaryfor(notjustcorrelatedwith)visualwordrecognitionby100 ms. Pulses were delivered to individually fMRI-defined LIFGpo/PCG in Dutch speakers 75-500 ms after stimulus onset during reading and picture naming. Reading and picture naming reactions times were significantly slower following pulses at 225-300 ms. Contrary to predictions, there was no disruption to reading for pulses before 225 ms. This does not provide evidence in favour of a functional role for LIFGpo/PCG in reading before 225 ms in this case, but does extend previous findings in picture stimuli to written Dutch words.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2010
Debate surrounds the precise cortical location and timing of access to phonological information d... more Debate surrounds the precise cortical location and timing of access to phonological information during visual word recognition. Therefore, using whole-head magnetoencephalography (MEG), we investigated the spatiotemporal pattern of brain responses induced by a masked pseudohomophone priming task. Twenty healthy adults read target words that were preceded by one of three kinds of nonword prime: pseudohomophones (e.g., brein-BRAIN), where four of five letters are shared between prime and target, and the pronunciation is the same; matched orthographic controls (e.g., broin-BRAIN), where the same four of five letters are shared between prime and target but pronunciation differs; and unrelated controls (e.g., lopus-BRAIN), where neither letters nor pronunciation are shared between prime and target. All three priming conditions induced activation in the pars opercularis of the left inferior frontal gyrus (IFGpo) and the left precentral gyrus (PCG) within 100 ms of target word onset. However, for the critical comparison that reveals a processing difference specific to phonology, we found that the induced pseudohomophone priming response was significantly stronger than the orthographic priming response in left IFG/PCG at ϳ100 ms. This spatiotemporal concurrence demonstrates early phonological influences during visual word recognition and is consistent with phonological access being mediated by a speech production code.
This thesis explored a possible role of Broca's area (specifically the pars opercularis of left i... more This thesis explored a possible role of Broca's area (specifically the pars opercularis of left inferior frontal gyrus and neighbouring precentral gyrus; LIFGpo/PCG) in accessing sublexical phonology during visual word recognition. In Experiments 1 to 4, behavioural masked sublexical phonological priming effects were tested during lexical decision and reading aloud in English. No sublexical phonological effects were found during the lexical decision tasks, but significant sublexical phonological priming effects were found during reading aloud. In Experiment 5, masked sublexical phonological priming effects were then tested during a silent reading task using magnetoencephalography. Sublexical phonological priming effects were localised to LIFGpo/PCG within ~200 ms for real word targets and within ~75 ms for nonword targets. This indicates an early sensitivity to sublexical phonological information at LIFGpo/PCG during silent reading of English. In Experiment 6 chronometric functional magnetic resonance imaging guided transcranial magnetic stimulation was used to create focal and transient virtual lesions to LIFGpo/PCG in order to test the hypothesis that the putative early sublexical phonological representations seen at LIFGpo/PCG are functionally necessary for visual word recognition. Dutch participants underwent transcranial magnetic stimulation during reading aloud as compared to picture naming.
Brain and language, 2012
a b s t r a c t Magnetoencephalography (MEG) has shown pseudohomophone priming effects at Broca's... more a b s t r a c t Magnetoencephalography (MEG) has shown pseudohomophone priming effects at Broca's area (specifically pars opercularis of left inferior frontal gyrus and precentral gyrus; LIFGpo/PCG) within 100msofviewingaword.ThisisconsistentwithBroca′sareainvolvementinfastphonologicalaccessduringvisualwordrecognition.Hereweusedonlinetranscranialmagneticstimulation(TMS)toinvestigatewhetherLIFGpo/PCGisnecessaryfor(notjustcorrelatedwith)visualwordrecognitionby100 ms of viewing a word. This is consistent with Broca's area involvement in fast phonological access during visual word recognition. Here we used online transcranial magnetic stimulation (TMS) to investigate whether LIFGpo/PCG is necessary for (not just correlated with) visual word recognition by 100msofviewingaword.ThisisconsistentwithBroca′sareainvolvementinfastphonologicalaccessduringvisualwordrecognition.Hereweusedonlinetranscranialmagneticstimulation(TMS)toinvestigatewhetherLIFGpo/PCGisnecessaryfor(notjustcorrelatedwith)visualwordrecognitionby100 ms. Pulses were delivered to individually fMRI-defined LIFGpo/PCG in Dutch speakers 75-500 ms after stimulus onset during reading and picture naming. Reading and picture naming reactions times were significantly slower following pulses at 225-300 ms. Contrary to predictions, there was no disruption to reading for pulses before 225 ms. This does not provide evidence in favour of a functional role for LIFGpo/PCG in reading before 225 ms in this case, but does extend previous findings in picture stimuli to written Dutch words.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2010
Debate surrounds the precise cortical location and timing of access to phonological information d... more Debate surrounds the precise cortical location and timing of access to phonological information during visual word recognition. Therefore, using whole-head magnetoencephalography (MEG), we investigated the spatiotemporal pattern of brain responses induced by a masked pseudohomophone priming task. Twenty healthy adults read target words that were preceded by one of three kinds of nonword prime: pseudohomophones (e.g., brein-BRAIN), where four of five letters are shared between prime and target, and the pronunciation is the same; matched orthographic controls (e.g., broin-BRAIN), where the same four of five letters are shared between prime and target but pronunciation differs; and unrelated controls (e.g., lopus-BRAIN), where neither letters nor pronunciation are shared between prime and target. All three priming conditions induced activation in the pars opercularis of the left inferior frontal gyrus (IFGpo) and the left precentral gyrus (PCG) within 100 ms of target word onset. However, for the critical comparison that reveals a processing difference specific to phonology, we found that the induced pseudohomophone priming response was significantly stronger than the orthographic priming response in left IFG/PCG at ϳ100 ms. This spatiotemporal concurrence demonstrates early phonological influences during visual word recognition and is consistent with phonological access being mediated by a speech production code.