Thursday, May 27, 2010

Syntax found in the brain -- not in Broca's area

Syntactic processing and Broca's area have been cozy bedfellows ever since work in the 1970s showed that patients with Broca's aphasia had difficulty comprehending syntactically complex sentences. Despite the fact that further lesion based evidence severely weakened the relationship (e.g., Broca's aphasics are pretty good at grammaticality judgments) subsequent PET and fMRI studies prolonged the marriage by showing that the comprehension of complex sentences activates Broca's area more than simple sentences. These days a look at the literature on Broca's area and sentence processing is full of controversy with proposals ranging from the region supporting syntactic movement processing (Grodzinsky) hierarchical structure and phrase structure building (Friederici), "linearization" (Bornkessel-Schlesewsky), and several more domain-general functions such as cognitive control (Novick), "unification" (Hagoort) and working memory (Caplan; Rogalsky/Hickok).

Meanwhile, evidence has been accumulating that the anterior temporal lobe may house a network that behaves much more like a syntactic computation system in that it seems to be highly correlated with the presence or absence of syntactic information in a sentence (Dronkers, et al. 2004; Friederici, et al., 2000; Humphries, et al. 2005,2006; Mazoyer et al., 1993; Rogalsky & Hickok, 2008; Stowe et al., 1998; Vandenberghe, Nobre, & Price, 2002).

A new study in Brain and Language weighs in on the issue using the psycholinguists' favorite work of literature, Alice in Wonderland. Unlike most psycholinguistic nods to Lewis Carroll (a.k.a. Charles Lutwidge Dodgson), the study by Jonathan Brennan and colleagues did not use Jabberwocky sentences, but instead had subjects listen to text from Alice while chillin' in a giant magnetic donut. The authors calculated word-by-word the amount of syntactic structure that was involved in integrating each word (basically a syntactic tree node counting analysis). These values were then correlated with the fMRI signal.

So what brain region correlated with syntactic structure? You guessed it: the anterior temporal lobe.

References

Brennan, J., Nir, Y., Hasson, U., Malach, R., Heeger, D., & Pylkkänen, L. (2010). Syntactic structure building in the anterior temporal lobe during natural story listening Brain and Language DOI: 10.1016/j.bandl.2010.04.002

Bornkessel-Schlesewsky I, Schlesewsky M, von Cramon DY. 2009. Word order and Broca's region: evidence for a supra-syntactic perspective. Brain Lang. 111:125-139.

Caplan D, Alpert N, Waters G, Olivieri A. 2000. Activation of Broca's area by syntactic processing under conditions of concurrent articulation. Hum Brain Mapp. 9:65-71.

Friederici AD, Meyer M, von Cramon DY. 2000. Auditory languge comprehension: An event-related fMRI study on the processing of syntactic and lexical information. Brain and Language. 74:289-300.

Grodzinsky, Y. (2001). The neurology of syntax: Language use without Broca’s area. Behavioral and Brain Sciences, 23(01), 1–21.

Hagoort P. 2005. On Broca, brain, and binding: a new framework. Trends Cogn Sci. 9:416-423.

Humphries C, Binder JR, Medler DA, Liebenthal E. 2006. Syntactic and semantic modulation of neural activity during auditory sentence comprehension. J Cogn Neurosci. 18:665-679.

Humphries C, Love T, Swinney D, Hickok G. 2005. Response of anterior temporal cortex to syntactic and prosodic manipulations during sentence processing. Human Brain Mapping. 26:128-138.

Mazoyer BM, Tzourio N, Frak V, Syrota A, Murayama N, Levrier O, Salamon G, Dehaene S, Cohen L, Mehler J. 1993. The cortical representation of speech. Journal of Cognitive Neuroscience. 5:467-479.

Novick JM, Trueswell JC, Thompson-Schill SL. 2005. Cognitive control and parsing: reexamining the role of Broca's area in sentence comprehension. Cogn Affect Behav Neurosci. 5:263-281.

Rogalsky C, Matchin W, Hickok G. 2008. Broca's Area, Sentence Comprehension, and Working Memory: An fMRI Study. Front Hum Neurosci. 2:14.

Rogalsky C, Hickok G. 2009. Selective Attention to Semantic and Syntactic Features Modulates Sentence Processing Networks in Anterior Temporal Cortex. Cereb Cortex. 19:786-796.

Stowe LA, Broere CA, Paans AM, Wijers AA, Mulder G, Vaalburg W, Zwarts F. 1998. Localizing components of a complex task: sentence processing and working memory. Neuroreport. 9:2995-2999.

Vandenberghe R, Nobre AC, Price CJ. 2002. The response of left temporal cortex to sentences. J Cogn Neurosci. 14:550-560.

2 comments:

Blink said...

Thank you very much for this very interesting article. I was just planning to look for articles about syntactic processing.
However, you mentioned Dronkers et al., 2004, but I don't see it in your references section.
Could you inform me of the title of this research, please ? Thanks for the consideration you will pay to my request.

Greg Hickok said...

Here's the Dronker's et al. ref:
Dronkers, N. F., Wilkins, D. P., Van Valin, R. D., Jr., Redfern, B. B., & Jaeger, J. J. (2004). Lesion analysis of the brain areas involved in language comprehension. Cognition, 92(1-2), 145-177.