Research

Language is a key human trait, and an essential aspect of our ability to interact with others. It allows us to combine and recombine a finite set of linguistic elements, to communicate an infinite range of meaning and ideas.

I am interested in understanding how this powerful communication system is processed in the mind and brain. My research focuses on the neural mechanisms that support spoken language comprehension. Using neuroimaging and behavioural techniques, I investigate how different properties of the speech input engage the underlying neural architecture to produce successful comprehension.

Neuro-cognitive mechanisms of language processing

PNAS
Bilateral netwok for pragmatic interpretation (orange) and LH network for grammatical combination (blue); from Bozic et al (2010) PNAS

Our work shows that speech information interfaces with two joint but distinct processing systems: a left lateralised (LH) fronto-temporal brain network that supports complex grammatical combination, and a broad bilateral network (whose functional properties are traced back to nonhuman primates) that supports semantic and pragmatic interpretation of the incoming utterance (Bozic et al, 2010; Marslen-Wilson, Bozic & Tyler, 2014).

Working in different languages, we showed that only grammatical complexity consistently activates the LH fronto-temporal network (English: Bozic et al, 2010; 2015; Polish: Szlachta et al, 2012; Bozic et al, 2013; Italian: Carota et al, 2016; Russian: Klimovich-Gray et al, forthcoming). On the other hand, the bilateral processing network seems to have extensive processing capacities: in addition to supporting the mapping of sound to meaning for simple words such as dog, it also supports the processing of perceptually complex words like claim (which have another word, clay, embedded in them; Bozic et al, 2010), derivationally complex words (warmth, archer; Bozic et al, 2013), as well as simple syntactic structures like ‘I sing’ or ‘the cat’ (Bozic et al, 2015).

HBM
Multivariate RSA results showing dissociation between the functional properties of the left-lateralised and the bilateral processing networks; from Bozic et al (2015)

 

The two networks integrate their processing via synchronised neural oscillations in real time, with the most prominent oscillations for grammatical combination triggered in the gamma band (20–60 Hz; Fonteneau, Bozic and Marslen-Wilson, 2015).

oscilations

Bilingualism

The second major strand of my research is bilingualism. I am interested in understanding the cognitive and the neural consequences of the ability to speak two (or more) languages.

With my PhD student Andrea Olguin we are testing the hypothesis that knowing two languages enhances our ability for selective attention and inhibition of irrelevant information. This view has received substantial attention in the scientific literature and the popular media, yet it remains controversial whether it holds true and what mechanisms might be supporting it.

Our research aims to address this controversy by examining the neural encoding of attended and unattended naturalistic speech; and comparing these effects in early bilinguals, late bilinguals, and monolinguals.

More to come..