tag:blogger.com,1999:blog-9048879464910781933.post6837183700036518995..comments2023-10-12T00:25:24.119-07:00Comments on Talking Brains: Lexical phonology and the posterior STGGreg Hickokhttp://www.blogger.com/profile/16656473495682901613noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-9048879464910781933.post-29449303017718803362008-08-18T16:14:00.000-07:002008-08-18T16:14:00.000-07:00Ok, I took a quick peek at the paper. I still lik...Ok, I took a quick peek at the paper. I still like it, but it isn't what I thought it was based on the abstract. I had thought it was a perceptual repetition priming effect, but it is not. It is a production effect. <BR/><BR/>Subjects listened to pseudowords and then immediately repeated each item. The manipulation was that some of the p-words were presented multiple times such that the subjects became familiar with them. This led to decreased repetition RTs and a decrease in signal in Spt. <BR/><BR/>Graves et al refer to the activation focus as "posterior superior temporal gyrus." Based on the coordinates (see Brad's comment above), and the projection of the activation onto an anatomical image, the activation is in the posterior planum temporale region: that is, in the posterior Sylvian fissure at parietal-temporal boundary (Spt). <BR/><BR/>Spt is a sensory-motor area that is not specific to speech. Although this region activates both during the perception and production of speech, in a study that Brad was deeply involved in, we showed that Spt responded just as well to perception and production of tonal/melodic stimuli as it does to speech stimuli (Hickok et al. 2003). Subsequent work by TB Wast (now former) grad student, Judy Pa, showed that this same region is modulated by output modality: Spt activates less when skilled pianists imagine playing a novel melody than when they imagine humming a novel melody (Pa & Hickok, 2008). This suggests that Spt is motor-effector specific, similar to sensory-motor areas in the parietal lobe (AIP, LIP, etc.). In other words, it walks and talks like a sensory-motor integration area...<BR/><BR/>Why does Spt show a familiarity effect in repeating non-words? We have suggested that this sensory-motor circuit is recruited for low frequency words that require sensory guidance, i.e., from phonological word forms stored (or recently activated in) the STS. So novel non-words maximally drive the system because production must be guided by the sensory representation. Once they are learned, however, "motor memory" can take some of the load and Spt activation is reduced. <BR/><BR/>All of this is consistent with the effects of lesions to this area, which are associated with condition aphasia, etc. etc. (see Hickok et al., 2003, Hickok & Poeppel, 2004, 2007 for details).<BR/><BR/><BR/>Buchsbaum, B., Hickok, G., & Humphries, C. (2001). Role of Left Posterior Superior Temporal Gyrus in Phonological Processing for Speech Perception and Production. Cognitive Science, 25, 663-678.<BR/><BR/>Hickok, G., Buchsbaum, B., Humphries, C., & Muftuler, T. (2003). Auditory-motor interaction revealed by fMRI: Speech, music, and working memory in area Spt. Journal of Cognitive Neuroscience, 15, 673-682.<BR/><BR/>Hickok, G. & Poeppel, D. (2004). Dorsal and ventral streams: A framework for understanding aspects of the functional anatomy of language. Cognition, 92, 67-99.<BR/><BR/>Hickok, G. & Poeppel, D. (2007). The cortical organization of speech processing. Nature Reviews Neuroscience, 8, 393-402.<BR/><BR/>Pa, J. & Hickok, G. (2008). A Parietal-Temporal Sensory-Motor Integration Area for the Human Vocal Tract: Evidence from an fMRI Study of Skilled Musicians. Neuropsychologia, 46, 362-368.Greg Hickokhttps://www.blogger.com/profile/16656473495682901613noreply@blogger.comtag:blogger.com,1999:blog-9048879464910781933.post-10779387421567357362008-08-18T15:09:00.000-07:002008-08-18T15:09:00.000-07:00Geez. I'm going to have to read this paper no...Geez. I'm going to have to read this paper now. This is interesting because (i) it is not where I'd expect to see activations associated with a "phonological lexicon" and (ii) this is not what we are finding in a very similar experiment. I would expect phonological word-forms to be stored/processed in the STS. This is where activations show up in speech minus non-speech comparisons and in the Okada & Hickok (2006) paper that contrasted high vs. low density words. In our own repetition priming experiment (Kenny Vaden's study -- still in the works!) we seem to be seeing STS activation. Maybe it is the non-word stimuli that are driving the Spt activation in the Graves study. <BR/><BR/>Okada, K. & Hickok, G. (2006). Identification of lexical-phonological networks in the superior temporal sulcus using fMRI. Neuroreport, 17, 1293-1296.Greg Hickokhttps://www.blogger.com/profile/16656473495682901613noreply@blogger.comtag:blogger.com,1999:blog-9048879464910781933.post-80652621360154141702008-08-18T14:18:00.000-07:002008-08-18T14:18:00.000-07:00just a note:the coordinates of their repetition ef...just a note:<BR/><BR/>the coordinates of their repetition effect are -51, -38, 22.<BR/><BR/>see the post "where is Spt?"<BR/>http://talkingbrains.blogspot.com/2007/05/where-is-area-spt.html<BR/><BR/>In the comments of that post I noted that the average Talairach coordinates for Spt (defined mainly in working memory paradigms) were at -50, -38, 20. Nearly identical coordinates and from their image in Figure 2 it's pretty clear that the cluster in located in the posterior portion of the planum temporale.<BR/><BR/><BR/>Brad BuchsbaumBrad Buchsbaumhttps://www.blogger.com/profile/10757537675625801119noreply@blogger.comtag:blogger.com,1999:blog-9048879464910781933.post-52008946407704915132008-08-17T21:29:00.000-07:002008-08-17T21:29:00.000-07:00Lexical-phonological access, if I understand the t...Lexical-phonological access, if I understand the term correctly, refers to phonological perception at a relatively high level of phonologic organization, eg. word-forms or holistic word perception. It can be used to avoid making claims you cannot resolve immediately about the precise level of phonological organization along linguistic divisions, phonetic, phonological, syllabic, etc., like when we find brain activity related to some aspect of speech sound processing, and it falls into the dark space of word/syllable/multiple-morphemes. <BR/><BR/>Since Graves and colleagues used repetition-priming, they are likely using single, repeating pseudowords or syllable-units of some sort to induce repetition inhibition. If they saw a reduction in activity, a conservative interpretation is not going to make specific claims about which organized phonological representation(s) was/were primed.Kenny Vadenhttps://www.blogger.com/profile/10302975210699422514noreply@blogger.comtag:blogger.com,1999:blog-9048879464910781933.post-71780602571099292572008-08-17T11:23:00.000-07:002008-08-17T11:23:00.000-07:00Sorry, but I am not sure to understand. In both ex...Sorry, but I am not sure to understand. In both experiments, repetition priming was observed in pSTG for both pseudowords and words?<BR/><BR/>So I do not understand the term 'lexical phonology'... I need to read this paper but I think that we need a reasonable definition of what are (?) speech perception, phonological processing, lexical processing and so on (also, I am not sure that 'word frequency is (always) a putative index of lexical phonological access').<BR/><BR/>Refering of one of mine favorite paper : 'the implicit goal of speech perception studies is to understand sublexical stages in the process of speech recognition'. Not so clear, especially regarding some 'lexical/non-lexical' phonological acess'...<BR/><BR/>Marc SatoAnonymousnoreply@blogger.com