Friday, December 7, 2018

Maps and Streams, Vocal Learning, and the Anatomy of Speech

The dual stream model of speech processing--originally proposed by Carl Wernicke in 1874 and modernized by me and David Poeppel in a series of three publications in 2000, 2004, and 2007--has become, it seems, the standard model of the field. It holds that speech processing is achieved along two task-dependent streams: a dorsal "how" stream important for speech production and a ventral "what" stream important for speech recognition.

Of course there is disagreement on the details, which is a healthy thing. The most prominent disagreement comes in the form of an alternative formulation by Rauschecker and Scott in a 2009 publication.  I commented on the problems with their proposal in a previous post. Here I want to highlight and discuss the main functional anatomic disagreement, which concerns the branching point of the two streams.  Rauschecker's monkey work suggests an early (A1) divergence, as this figure from R&S indicates:

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R&S, sticking close to the monkey anatomy, translate that into a human architecture with the same branch point, meaning that everything ~caudal to A1 is dorsal and everything ~rostral to A1 is ventral.



In contrast, we've argued that the branch point is fairly deep into the system, in the vicinity of the pSTS (yellow phonological network in figure) or caudal parabelt in monkey auditory cortex anatomy terms:



The evidence for this comes from a variety of sources (neuropsych, imaging) that we have recited again and again in various publications. I won't rehash it here. For some recent evidence for an "auditory phonological area" that is consistent with the H&P proposal, see this Twitter thread.

An advantage of the R&S view is that it can be viewed as more parsimonious or conservative in the evolutionary sense, sticking closer to the anatomy as it is understood in the monkey. I think this is a reasonable tack. The question, then, is whether there is empirical justification for a different architecture in the human. My long-time position on this is that the empirical evidence is overwhelming and therefor justifies a different architecture in humans compared to macaques.
but here I want to step back and consider some functional-behavioral arguments that I think reconcile to some extent the R&S and H&P viewpoints and show that they are not all that different after all.

The basic insight is that the auditory-motor repertoire of monkeys and humans is dramatically different. There is general agreement that the vocal-learning capacities of monkeys is limited whereas humans are arguably the most prodigious vocal learners in the animal kingdom. What this means is that the auditory-motor repertoire of monkeys is going to be limited to relatively simple behaviors like orienting to sound and not to behaviors where the perceived sound must be reproduced by the monkey. Perhaps it is no surprise that the monkey dorsal stream, in Rauschecker's hands (cf, Middlebrooks), is spatial perception oriented.

Speech is different. The phonological form of a word must be used both as a means to access the meaning of the word, a ventral stream "what" function, and as a target for a motor speech action, a dorsal stream "how" function.  Now, look back at the first figure in this post and play natural selection for a moment. If you were going to evolve a network that could represent higher-level information about word forms AND use them in both ventral and dorsal streams, where would you put such a network? A good candidate is the lighter shaded area just ventrolateral to A1 and extending posterior from there. This is the yellow shaded box/area in the H&P figure, the "Mid-post STS", which in our model is part of both the ventral and dorsal streams.  R&S assign this zone as part of the dorsal stream (red in their human architecture figure) but they acknowledge some interaction between that posterior zone and the more anterior portion of their ventral stream, as the arrow in their figure indicates.

What I'd like to communicate with these points is that (1) the H&P model architecture is perfectly consistent the monkey architecture assuming some reasonable evolutionary expansions, (2) R&S assume a similar expansion into that same zone in humans, meaning that (3) the two models are not really that different at this level: H&P refer to the mid-posterior zone as part of both streams whereas R&S call it part of the dorsal stream that nonetheless interacts with both streams.

Conclusion: perhaps there is more agreement about the details of the dual stream architecture than the pictures and claims suggest.

Monday, November 26, 2018

POSTDOCTORAL POSITIONS at the BCBL- Basque Center on Cognition Brain and Language (San Sebastián, Basque Country, Spain) www.bcbl.eu (Center of excellence Severo Ochoa)


The Basque Center on Cognition Brain and Language (San Sebastián, Basque Country, Spain) offers three postdoctoral positions in three main broad areas or research:
(1)-Language, reading and developmental disorders: How language acquisition, comprehension, production, and reading take place in the human brain. Special attention will be paid to language disorders and the development of computerized tools for their early diagnosis and treatment.
(2)-Multilingualism and second language learning: The cognitive and brain mechanisms of language acquisition and processing in a second language. Special attention will be paid to multilingualism within the school system and to the development of new educational technologies for second language learning.
(3)- Neurodegeneration, brain damage and healthy aging: Language and Cognition: Early cognitive and brain markers related to language for neurodegenerative diseases (Alzheimer, Parkinson); neural plasticity and language functions through brain stimulation in the awake patient during surgical brain operations; developing of computerized diagnostic and training tools for aphasic patients and neurodegenerative diseases.
The BCBL (center of excellence Severo Ochoa) promotes a rich research environment without substantial teaching obligations. It provides access to the most advanced behavioral and neuroimaging techniques, including 3 Tesla MRI, a whole-head MEG system, four ERP labs, a NIRS lab, a baby lab including an eyetracker, two eyetracking labs, and several well-equipped behavioral labs.  There are excellent technical support staff and research personnel (PhD and postdoctoral students). The positions have a term of appointment of 2 years with a possible renewal.

We are looking for cognitive neuroscientists or experimental psychologists with a background in psycholinguistics and/or neighboring cognitive neuroscience areas, computational modelers, and physicists and/or engineers with fMRI/MEG expertise.

Candidates should have a strong publication track record.

Deadline: February 1rst, 2019.

We encourage immediate applications as the selection process will be ongoing and the appointment may be made before the deadline.

To submit your application please follow this link: http://www.bcbl.eu/calls, applying for Postdoc_SO_2018 and upload:
  1. Your curriculum vitae.
  2. A cover letter/statement describing your research interests (4000 characters maximun)
  3. The names of two referees who would be willing to write letters of recommendation

For information about the positions, please contact Manuel Carreiras (info@bcbl.eu).

Friday, November 16, 2018

POSTDOCTORAL RESEARCH POSITIONS IN THE NEUROBIOLOGY OF LANGUAGE AT THE UNIVERSITY OF TEXAS AT HOUSTON



Multiple Postdoctoral research positions are available in the Tandon Lab at The University of Texas in Houston as part of the newly formed Texas Epilepsy Neurotechnologies and Neuroinformatics (TENN) Institute. Positions are funded either via multi-year Institute funding or by NIH funds (U01 and R01). The lab uses multimodal approaches – fMRI, lesional analysis following epilepsy surgery, intracranial recordings and direct stimulation to create and validate network level representations of language. Lab Collaborators include Greg Hickok (UCI), Stanislas Dehaene (NeuroSpin), Nathan Crone (JHU), Simon Fisher Baum (Rice) and Xaq Pitkow (Rice-Baylor); the post-doc will benefit from a close interaction with these experts in the fields of reading, semantics, speech production and computational neuroscience.

The selected individual must have a Ph.D. in one or more of the following: neuroscience, psychology, cognitive science, mathematics, electrical engineering or computer science. Previous experience in neural time series data analysis, functional imaging studies of language, or studies of speech production are desirable – but not crucial. They must possess the ability to independently code in any or all of the following: MATLAB, R or Python.

They are expected to be highly motivated, team players with a passion to study cognitive processes using any or all of the various modalities available in the lab – imaging, direct recordings and closed-loop cortical stimulation – in humans. Given the multiple unpredictable variables and privacy issues around data collection in human patients, the individual must possess high ethical and professional standards and be adaptable. A strong publication record and excellent academic credentials are highly desirable.

CONTACT:

More information @ www.tandonlab.org

Wednesday, October 24, 2018

BCBL Post Doc on neurocomputational basis of language learning and statistical learning

The Basque Center on Cognition Brain and Language – BCBL- (San Sebastián, Basque Country, Spain) is offering a postdoctoral position focused on neurocomputational basis of language learning and statistical learning, as part of ERC-funded research project (PI: Ram Frost).

The successful candidate will join an interdisciplinary team of researchers studying the cognitive and neural mechanisms underlying statistical learning and language learning from behavioural and computational perspectives. Work undertaken related to this position will contribute to integrating these different perspectives in an explicit neurocomputational framework.

We are interested in candidates with strong computational expertise, particularly in the domain of computational linguistics/neural networks /connectionist modelling / deep learning. Candidates should be proficient in python programming. Use of distributed computational techniques (parallelization on GPUs or CPUs) is an asset. Applicants able to demonstrate such computational expertise will be considered from the cognitive sciences, broadly construed, including psychology, computational linguistics, computational neuroscience, computer science, machine learning, and cognitive science.

In addition to strong computational skills, the successful candidate will demonstrate a high level of independence, and a strong publication record. As part of a broader ERC-funded statistical learning research program, the candidate will also have the opportunity to interact with and (if desired) complete research stays at related research groups at the BCBL, the Hebrew University, and the University of Toronto, so as to better integrate the computational models with related behavioural and neural data.

Deadline: December 15th, 2018.

To submit your application please follow this link: http://www.bcbl.eu/calls, applying for Computational Postdoc 2018_02 and upload:
  1.  A curriculum vitae.
  2. A cover letter/statement describing your research interests (4000 characters max).
  3. Two reference letters submitted directly by the referees through the outline system.
 For more information about the specifics of the position, please contact Ram Frost (ram.frost@mail.huji.ac.il) and for broader information about the BCBL please contact Manuel Carreiras (info@bcbl.eu)

Monday, October 15, 2018

Ph.D. training opportunities at BCBL, San Sebastian, Spain

Dear colleagues,

The Spanish Ministry of Science, Innovation and Universities has published the call for PhD Students 2018. The application period is from 09/10/18 to 29/10/18 at 15:00h.

The call offers up to 4 PhD Student positions to join the BCBL within the Severo Ochoa accreditation (SEV-2015-0490). 

The PhD students will join RESEARCH LINE “Language, reading and developmental disorders” and will work under the supervision of Prof. Carreiras, Dr. Lallier and Dr. Molinaro respectively and RESEARCH LINE "Neurodegeneration, brain damage and in healthy aging: Language and Cognition(Language and Memory Control)" under the supervision of Dr. Paz-Alonso
For more information:

Please, should you be interested in the position, do not hesitate to contact Ana Fernández (a.fernandez@bcbl.eu), Project Manager of the BCBL. She will be very pleased to support you in the submission process.





Dear colleagues,

The Spanish Ministry of Science, Innovation and Universities has published the call for PhD Students 2018. The application period is from 9/10/18 to 29/10/18 at 15:00h.

The call offers up to 1 PhD Student position (4-year contract ) to join the following Research Funded Project:

PSI2017-82941-P- REFO – Phonemic retuning induced by reading acquisition – PI Dr. Clara Martin
Key words: Reading acquisition, Phonemic retuning, Phoneme-grapheme conversion, Dyslexia, Word perception and production 
Summary of the project: 
Learning to read changes the way one perceives spoken words and boosts performance in phonemic tasks. In fact, in expert readers, spoken words with inconsistent phonemes (i.e., phonemes that have many spellings) are recognized slower and less accurately than those with consistent phonemes (i.e., that have only one possible spelling; “orthographic consistency effect”). Plus, reading acquisition induces a boost in phonemic awareness (i.e., ability to distinguish and manipulate the minimal sounds of speech). Here, we make the claim that those consequences of reading acquisition (RA) can be explained by a unique and common phenomenon, which is the recalibration of phonemic representations (PRs) by literacy acquisition. More specifically, we claim that (1) PRs (in perception and production) become more stable (less dispersed) when learning to read, accounting for the phonemic awareness boost during RA. We also argue that (2) this recalibration varies with the consistency of the reading system (i.e., (in)consistency of phoneme-to-grapheme conversions), which would in turn explain the “orthographic consistency effect”. We will explore such recalibration by means of the first longitudinal cross-linguistic study examining the position and dispersion of PRs, together with processing speed (both in perception and production of phonemes and words). We will compare Spanish and French children on target phonemes that are shared by the two languages but that do not systematically follow the same phoneme-to-grapheme conversion rules (e.g., the phoneme /b/, consistent in French -always spelled ‘b’- and inconsistent in Spanish -spelled ‘b’ or ‘v’-). Children will be tested in a longitudinal design before and after RA in order to explore the developmental pattern of phonemic recalibration during literacy acquisition. By comparing dyslexic children with their matched controls, we will also test the hypothesis that (3) stabilization of PRs during RA is impaired in dyslexic patients. Such result would account for the (previously reported) lack of phonemic awareness boost and “consistency effects” in this population. This proposal provides the first systematic investigation of phonemic recalibration during literacy acquisition, which is highly relevant for the fields of language development and impaired reading acquisition, enabling better detection of risks of dyslexia and the creation of remediation tools. 


Individuals interested in the PhD position should have:
  •  Strong theoretical and methodological background in cognitive neuroscience or experimental psychology with a special focus on psycholinguistics and/or neighboring cognitive neuroscience areas.
  •  Good level of written and spoken English.
Research experience in the domain of speech perception and production, especially with acoustics/phonetics analysis techniques, will be an asset. Possession of a Master degree in the area of psycholinguistics or cognitive sciences (or any other related area) is highly recommended and will be positively valued. Speaking Spanish and/or French would also be a plus to facilitate preparation of stimulus materials and running experiments with Spanish and French native participants.

For more information:
Please, should you be interested in the position, do not hesitate to contact Ana Fernández (a.fernandez@bcbl.eu), Project Manager of the BCBL. She will be very pleased to support you in the submission process.

Wednesday, August 15, 2018

ECoG Post-doc opportunities with Nitin Tandon, Stan Dehaene, Nathan Crone, Xaq Pitkow & me


POSTDOCTORAL RESEARCH POSITION
SPONSORED BY BRAIN INITIATIVE GRANT

Postdoctoral research positions are available in the lab of Nitin Tandon at Houston. This position is funded by a BRAIN Initiative U01 grant funded project that uses electro-corticographic (ECoG) recordings and fMRI on a large cohort (n=80) to evaluate psycholinguistic models of reading and speech production to create network level representation of language. Collaborators on the project include Greg Hickok, Stanislas Dehaene, Nathan Crone and Xaq Pitkow; the post-doc will benefit from a close interaction with these experts in the fields of reading, semantics, speech production and computational neuroscience.
The selected individuals are expected to be a highly motivated, team players with a passion to study cognitive processes using imaging, direct recordings and closed-loop cortical stimulation in humans. They will be responsible for
1)    data collection in the epilepsy monitoring unit and in the MRI scanner
2)    ECoG data analysis using an analysis pipelines existent in the lab and via the development of innovative analytic strategies including machine learning and AI approaches
3)    data presentation at conferences and manuscript preparation.
The selected individual must have a Ph.D. in one or more of the following: neuroscience, psychology, cognitive science, mathematics, electrical engineering or computer science. Previous experience in neural time series data analysis, functional imaging studies of language, or studies of speech production are desirable – but not crucial. They must possess the ability to independently code in any or all of the following: MATLAB, R or python.

Given the multiple unpredictable variables and privacy issues around data collection in human patients, the individual must possess high ethical and professionalism standards, be able to adapt to a changing environment, reorganize schedules dynamically, and work with short deadlines. A strong publication record and excellent academic credentials are highly desirable.

CONTACT DR. NITIN TANDON:
Nitin.Tandon@uth.tmc.edu