Two principles of organization in the prefrontal cortex are cognitive hierarchy and degree of automaticity

Abstract

The lateral prefrontal cortex is known to be organized by cognitive hierarchies following a posterior-to-anterior gradient. Here we test whether this model applies across different cognitive domains by varying levels of cognitive hierarchy in first language, second language and non-language domains. These domains vary in their degree of automaticity with first language being the most automatic. For second language/non-language a clear gradient pattern of activation depending on the level of hierarchy is observed in the prefrontal cortex with the highest level of hierarchy recruiting its most anterior region, whereas for first language the highest level of hierarchy recruits its most posterior region. Moreover, second language/non-language and first language differ in the structural connectivity of their underlying networks. The current data strongly suggest that functional segregation of the prefrontal cortex is determined by cognitive hierarchy and the degree of automaticity.

A rostro-caudal axis for language in the frontal lobe: The role of executive control in speech production

“…Similarly, studying the "regional co-variation" of this network in language processing tasks and tasks of nonverbal executive control should provide valuable information as to the functional (and potentially evolutionary) relationship between the human capacity for language and general reasoning and action. Importantly, this putative relationship brings with it the caveat that the involvement of pFC regions in different speech production tasks may not so much reflect executive processes as tied to speech production per se than to the various contingencies in which speech is elicited (Gherig et al, 2012;Jeon and Friederici, 2013). Future research aiming at disentangling such co-variation will face this methodological problem, necessitating careful construction of its materials and methods, as well as ecologically informed interpretation of the results.…”

“…Of highest importance is the necessity to establish the functional-anatomic relationships between the various executive components of pFC and posterior primary and multisensory regions engaged in phonological perception and storage, lexical-conceptual memory and sensorimotor interface (Hickok and Poeppel, 2007), as well as other abilities often deemed 'peripheral' to language processing such as reading (Dehaene and Cohen, 2011), music (Uddén and Bahlmann, 2012) or bilingualism (Bialystok, 2009;Jeon and Friederici, 2013). In the mean time, this discussion hopefully shows the theoretical and empirical import of a comprehensive picture of the frontal lobe as the main executive component of human language.…”

Broca's area processes the hierarchical organization of observed action

“…This effect was likely due to the extensive piano experience of the participant and the concurrent acquisition of neuronal mechanisms in Broca's area that represent action hierarchy. Based on the findings by Rüschemeyer et al (2006), as well as Jeon and Friederici (2013), it is conceivable that Broca's area is not necessarily activated by processing a simple hand motion action. Rather, Broca's area may come into play only when processing an unfamiliar hand motion sequence.…”

“…However, BA 44 of non-native speakers is consistently active, regardless of the degree of complexity of sentences (see also Rüschemeyer et al, 2005; Yokoyama et al, 2006). Moreover, Jeon and Friederici (2013) demonstrated that the syntactical analysis of complex non-native sentence recruited BA 47. Thus, only BA 44 of native speakers showed complexity-dependent activation.…”

Maturation of language networks in children: A systematic review of 22years of functional MRI

“…The emergence of this skill coincides with structural maturation of dorsal language tracts in the brain (Brauer, Anwander, Perani, & Friederici, 2013). These tracts interconnect lower-level regions of the Perception-Action Cycle (Jeon & Friederici, 2013) and support sound-to-motor mapping in adults (Saur et al, 2008). We hypothesise that these dorsal tracts -and the cortical regions they connect -become increasingly involved in language processing as skills become automatised during childhood (at least for relatively simple language skills).…”