A Study of Word Complexity Under Conditions of Non-experimental, Natural Overt Speech Production Using ECoG

Abstract

The linguistic complexity of words has largely been studied on the behavioral level and in experimental settings. Only little is known about the neural processes underlying it in uninstructed, spontaneous conversations. We built up a multimodal neurolinguistic corpus composed of synchronized audio, video, and electrocorticographic (ECoG) recordings from the fronto-temporo-parietal cortex to address this phenomenon based on uninstructed, spontaneous speech production. We performed extensive linguistic annotations of the language material and calculated word complexity using several numeric parameters. We orthogonalized the parameters with the help of a linear regression model. Then, we correlated the spectral components of neural activity with the individual linguistic parameters and with the residuals of the linear regression model, and compared the results. The proportional relation between the number of consonants and vowels, which was the most informative parameter with regard to the neural representation of word complexity, showed effects in two areas: the frontal one was at the junction of the premotor cortex, the prefrontal cortex, and Brodmann area 44. The postcentral one lay directly above the lateral sulcus and comprised the ventral central sulcus, the parietal operculum and the adjacent inferior parietal cortex. Beyond the physiological findings summarized here, our methods may be useful for those interested in ways of studying neural effects related to natural language production and in surmounting the intrinsic problem of collinearity between multiple features of spontaneously spoken material.

Single-neuronal elements of speech production in humans

“…Using Neuropixels probes to obtain acute, fine-scaled recordings from single neurons in the language-dominant prefrontal cortex [3][4][5][6] in a region proposed to be involved in word planning [3][4][5][6][7][8][9][10][11][12] and production [13][14][15][16] -we find a strikingly detailed organization of phonetic representations at a cellular level. In particular, we find that the activities of many of the neurons closely mirrored the way in which the word sounds were produced, meaning that they reflected how individual planned phonemes were generated through specific articulators 58,59 .…”

“…As part of deep brain stimulator implantation at our institution, participants are often awake and microelectrode recordings are used to optimize anatomical targeting of the deep brain structures 46 . During these cases, the electrodes often traverse part of the posterior language-dominant prefrontal cortex [3][4][5][6] in an area previously shown be involved in word planning [3][4][5][6][7][8][9][10][11][12] and sentence construction [13][14][15][16] and which broadly connects with premotor areas involved in their articulation [51][52][53] and lexical processing [17][18][19] by imaging studies (Extended Data Fig. 1a,b).…”

“…1a; section on 'Acute intraoperative single-neuronal recordings'). These recordings were obtained from the posterior middle frontal gyrus 10,[46][47][48][49][50] in a region known to be broadly involved in word planning [3][4][5][6][7][8][9][10][11][12] and sentence construction [13][14][15][16] and to connect with neighbouring motor areas shown to play a role in articulation [17][18][19] and lexical processing [51][52][53] (Extended Data Fig. 1a).…”

“…To produce fluent speech, linguistic analyses suggest a structured succession of processes involved in planning the arrangement and structure of phonemes in individual words 1,2 . These processes are thought to occur rapidly during natural speech and to recruit prefrontal regions in parts of the broader language network known to be involved in word planning [3][4][5][6][7][8][9][10][11][12] and sentence construction [13][14][15][16] and which widely connect with downstream areas that play a role in their motor production [17][18][19] . Cortical surface recordings have also demonstrated that phonetic features may be regionally organized 20 and that they can be decoded from local-field activities across posterior prefrontal and premotor areas [21][22][23] , suggesting an underlying cortical structure.…”

Perspectiva de Reducir la Edad de la Responsabilidad Penal Frente a Delitos Contra el Patrimonio

“…En ese sentido, este proceso permitió la formulación de un enunciado del problema con respecto a los fenómenos observados (Islam y Faraj, 2022). Este enfoque adoptó un diseño de análisis temático permite una comprensión integral (Glanz, et al, 2022).…”