White Matter Connectivity in Persistent Developmental Stuttering

Aslant tract (cyan) in a AWS and CON subject [Kronfeld Duenias et al., BSAF 2016]
Developmental stuttering affects about 5% of the children and 1% of the adult population. Our lab examines the differences in white matter pathways and functional responses between adults who do and do not stutter, and relates white matter properties to cognitive skills in adults who stutter. We used dMRI to quantify anatomical properties of white matter in specific language and motor pathways. Together with our colleagues Ofer Amir and Ruth Ezrati-Vinacour (Tel-Aviv University) we further assessed performance on a wide array of cognitive tasks. Our findings demonstrate the involvement of the frontal aslant tract in stuttering (Kronfeld Duenias et al., 2016). This newly discovered pathway has previously been related to performance on semantic fluency tasks, and is believed to be part of a novel “motor pathway” involved in language production. Further discoveries have established the involvement of right dorsal tracts and frontal callosal pathways in stuttering. These findings draw a picture of stuttering as a complex developmental clinical condition that involves multiple pathways in both hemispheres, as well as intact communication between the hemispheres. (Funding: ISF grant 513/11 to Ben-Shachar and Amir)

  • Kronfeld-Duenias, V., Amir, O., Ezrati-Vinacour, R., Civier, O. and Ben-Shachar, M. (2016). Dorsal and ventral language pathways in persistent developmental stuttering. Cortex 81, 79-92.
  • Kronfeld-Duenias, V., Amir, O., Ezrati-Vinacour, R., Civier, O., Ben-Shachar, M. (2014). The frontal aslant tract underlies speech fluency in persistent developmental stuttering. Brain Structure and Function 221, 365–381.
  • Civier, O., Kronfeld-Duenias, V., Amir, O., Ezrati, R., and Ben-Shachar, M. (2015). Reduced fractional anisotropy in the anterior corpus callosum is associated with reduced speech fluency in persistent developmental stuttering. Brain and Language 143, 20-31.
  • Halag-Milo, T., Stoppelman, N., Kronfeld-Duenias, V., Civier, O., Amir, O., Ezrati-Vinacour, R. and Ben-Shachar, M. (2016). Beyond production: Brain responses during speech perception in adults who stutter. NeuroImage: Clinical 11, 328–338.

Extracting word structure information in Hebrew

Responses to Hebrew pseudowords consisting of real roots show reduced accuracy and increased RT compared to invented roots. Yablonski and Ben-Shachar, In Press.

Morphological structure provides valuable information about word meaning, spelling, and word pronunciation, particularly in Hebrew, a language with a uniquely deep orthography. We are beginning to study the neural pathways that underlie word structure extraction in Hebrew and English readers. In two recent experiments, we have established that adult Hebrew readers extract information about root-reality when exposed to pseudonouns and pseudoverbs (Yablonski and Ben-Shachar, In Press). In a recent collaboration with Jo Taylor and Kathy Rastle (Royal Holloway, University of London), we show that similar processes in English readers are associated with specific white matter pathways (work in progress). We plan to assess the contribution of these pathways for morphological processing in Hebrew readers, to examine the universality of morphological pathways across orthography and language systems.

  • Yablonski, M. and Ben-Shachar, M. (In Press). The Morpheme Interference Effect in Hebrew: a Generalization across the Verbal and Nominal Domains. The Mental Lexicon 11(2), 277-307.

Functional responsivity within the reading pathways of adults and children

Major cortical regions and fiber tracts in the reading pathways [Ben-Shachar et al., CONB 2007]
Prior work by Ben-Shachar, Wandell and colleagues examined the functional responsivity and sensitivity of specific cortical regions within the reading system in school age children (Ben-Shachar et al., 2007, 2011), as well as the white matter pathways that communicate information between these cortical regions (Ben-Shachar et al., 2007; Yeatman et al., 2011, 2012). We have shown that adults show enhanced sensitivity to written words in the ventral occipito-temporal cortex, and that this enhanced sensitivity develops between the ages 7 to 12. By the time the child reaches 12 years of age, their sensitivity typically matches the values measured in adults. Moreover, change in cortical sensitivity to written words correlates with change in the ability to recognize written words fast. In collaboration with colleagues in Stanford (Wandell) and Tel-Aviv University (Mukamel, Friedmann), we continue to study cortical responses to letter and word position (Ossmy et al., Cortex 2014 and ongoing studies). (Funding: BSF 2011314 to Ben-Shachar, Wandell and Friedmann)

  • Ossmy, O., Ben-Shachar, M. and Mukamel, R. (2014). Decoding letter position in word reading. Cortex 59, 74-83.
  • Ben-Shachar, M., Dougherty, R. F. and Wandell, B. A. (2007). White matter pathways in reading. Current Opinions in Neurobiology 17: 258-270.
  • Ben-Shachar, M., Dougherty, R.F., Deutsch, G.K., and Wandell, B.A. (2011). The development of cortical sensitivity to visual word forms. Journal of Cognitive Neuroscience 23(9), 2387-99.
  • Yeatman, J.D., Dougherty, R.F., Rykhlevskaia, E., Sherbondy, A.J., Deutsch, G.K., Wandell, B.A. and Ben-Shachar, M. (2011). Anatomical Properties of the Arcuate Fasciculus Predict Phonological and Reading Skills in Children. Journal of Cognitive Neuroscience 23(11), 3304-17.
  • Ben-Shachar, M., Dougherty, R. F., Deutsch, G. K., and Wandell, B. A. (2007). Contour and word form processing in human ventral occipito-temporal cortex. Cerebral Cortex 17, 1604-11.

White matter pathways underlying sensorimotor synchronizationBlecher_fig3

Auditory-motor synchronization is hypothesized to rely on a tight coupling between auditory and motor neural systems. In a recent study (Blecher, Tal and Ben-Shachar, NeuroImage 2016), we tested this hypothesis and examined the contribution of fronto-temporal and callosal connections to specific measures of rhythmic synchronization. We found significant correlations between asynchrony and fractional anisotropy in the left (but not right) arcuate fasciculus and in the temporal segment of the corpus callosum. These results indicate that auditory-motor synchronization skills are associated with anatomical pathways that have been previously related to phonological awareness, thus offering a possible anatomical basis for the behavioral covariance between these abilities. In ongoing studies, we continue to test the predictions that emanate from this study in adults, children and in atypical developmental populations.

  • Blecher, T., Tal, I. and Ben-Shachar, M. (2016). White matter microstructural properties correlate with sensorimotor synchronization abilities. NeuroImage 138, 1-12.