Biomedical subjects

Peter F Dominey

Publications and source records attributed to Peter F Dominey.

5 recordsLinked to original sources

PubMed2005

ERP correlates of lexical analysis: N280 reflects processing complexity rather than category or frequency effects.

In the context of language processing, the N280 is an anterior negative event-related potential profile associated with the lexical categorization of grammatical function words versus content words. Subsequent studies suggested that this effect was related to word statistics including length and frequency in the lexicon. The current research tests the hypothesis that the N280 effect is related to an index of grammatical complexity. We recorded event-related potentials during a sentence reading task. Comparing content versus function words revealed the classic N280. Within function words, we compared the relative pronouns 'qui' and 'que' (which are identical for length and frequency) that in French indicate a subsequent simple (subject-subject) and complex (subject-object) relative clause, respectively. A left anterior N280 effect was observed only for 'que', supporting our hypothesis that the N280 reflects grammatical complexity that can be confounded with lexical category and statistical properties.

Adult↗

PubMed2005

Linear recursive distributed representations.

Connectionist networks have been criticized for their inability to represent complex structures with systematicity. That is, while they can be trained to represent and manipulate complex objects made of several constituents, they generally fail to generalize to novel combinations of the same constituents. This paper presents a modification of Pollack's Recursive Auto-Associative Memory (RAAM), that addresses this criticism. The network uses linear units and is trained with Oja's rule, in which it generalizes PCA to tree-structured data. Learned representations may be linearly combined, in order to represent new complex structures. This results in unprecedented generalization capabilities. Capacity is orders of magnitude higher than that of a RAAM trained with back-propagation. Moreover, regularities of the training set are preserved in the new formed objects. The formation of new structures displays developmental effects similar to those observed in children when learning to generalize about the argument structure of verbs.

Algorithms↗

PubMed2003

Training with cognitive sequences improves syntactic comprehension in agrammatic aphasics.

A major open question in cognitive neuroscience concerns the modularity of language: does human language rely, in part, on neural processes that are not language specific? Such reliance would predict that learning should transfer between non-linguistic and linguistic domains via this common neural basis. To test this prediction, we studied effects of non-linguistic cognitive sequence training on syntactic comprehension of six left-hemisphere damaged aphasic patients. Syntactic comprehension impairment was quantified before and after 10 weeks of training on a non-linguistic sequence processing task. This task used a transformational rule specifically corresponding to the transformation required for understanding a particular type of sentence referred to as relativised. Non-linguistic sequencing improved significantly with training (day effect: F(9,45)=3.7, <0.005). Moreover, a significant transfer of this improvement was observed for relativised, but not active nor passive sentences (pre-post x type interaction: F(2,10)=4.72, <0.05). The specificity of this transfer indicates that language relies partially on functional and neural processes that are not language specific.

Aged↗

PubMed2003

Neurological basis of language and sequential cognition: evidence from simulation, aphasia, and ERP studies.

The current research addresses the hypothesis that certain aspects of sequential cognition have made substantial contributions to the human language processing capability, from a functional neurophysiology perspective. We first describe a cognitive sequence processing model that was developed based on the functional neuroanatomy of primate cortex and basal ganglia. We demonstrate how this model is capable of simulating the behavior of human infants in extracting serial, temporal and abstract structure from language-like sound sequences as revealed in recent psycholinguistic experiments. We then demonstrate how, through training, this model can perform adult level syntactic comprehension, based on dissociated processing streams for open vs. closed class words. The model subsequently predicts: (1) that impaired syntactic processing (as in agrammatic aphasia) will be associated with impairments in corresponding non-linguistic cognitive sequencing tasks, and (2) that neurophysiological processes (as revealed by ERPs) involved in syntactic processing should also be involved in the corresponding non-linguistic cognitive sequencing tasks. Data confirming these predictions are reviewed. We conclude that the study of sequential cognition will provide a new paradigm for the investigation of the neurophysiological bases of language.

Aphasia, Broca↗

PubMed2002

Human brain potentials reveal similar processing of non-linguistic abstract structure and linguistic syntactic structure.

This research tested the hypothesis that shared or related neurophysiological processes are required for treating (a) non-linguistic abstract structure and (b) some aspects of linguistic syntactic structure. In language, one syntactic structure can be used to create an open class of sentences. We have previously proposed a relation between this generative aspect of syntactic structure and the abstract structure of non-linguistic sequences. For instance, the sequences 'ABCBAC' and 'DEFEDF' have different serial order or serial structure, but share the same abstract structure '123213'. Our recent studies of neuropsychology, simulation and ERPs argued that similar neurophysiological processes are involved in treating non-linguistic abstract structure and certain aspects of linguistic syntactic structure. The current research tests this hypothesis by examining the ERP profile evoked during the processing of non-linguistic sequences vs. sentences. Ten healthy subjects were trained to discriminate between syntactically correct and incorrect sequences and sentences presented visually on a video screen. During the subsequent ERP recording, subjects discriminated between correct and incorrect sequences and sentences presented visually on the screen. This discrimination task yielded, for anomalies in both the abstract and syntactic conditions, a late positivity around 550 ms with partially overlapping topography. These results support our hypothesis that shared or related neurophysiological processes are required for treating non-linguistic abstract structure and aspects of linguistic syntactic structure. However, they also suggest that the overlap between these two types of processing is not complete.

Adult↗