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Biomedical subjects

A D Friederici

Publications and source records attributed to A D Friederici.

80 records · Page 5Linked to original sources
PubMed1983

Aphasics' perception of words in sentential context: some real-time processing evidence.

The perception of words belonging to different grammatical classes was investigated in Wernicke's and Broca's aphasics. The experimental used a word monitoring task, which varied the target's word class, as well as the sentential context. The sensitivity to semantic context was very similar for both aphasic groups. Processing differences for the two groups were found, however, with respect to different word classes. It appears that Broca's aphasics are unable to process grammatical morphemes as features of a phrasal frame. Wernicke's aphasics, however, seem to retain the ability to process syntactic as well as some semantic information, at least, during sentence perception.

Adult↗
PubMed1982

Syntactically and semantically based computations: processing of prepositions in agrammatism.

Six Broca's and six Wernicke's aphasics were tested for their processing of prepositions in different linguistic tasks which placed increasing emphasis on the use of syntactic knowledge. Subjects performed a variety of tasks involving the production and perception of sentences containing prepositions. Agrammatics' production performance was very poor. Although their comprehension performance was superior to production when asked to complete a sentence selecting the target item out of four prepositions their comprehension performance was no longer superior to production in tasks where correct performance strongly depends upon the knowledge of sentence form. These results support the view of a general incapacity of agrammatics to use knowledge of sentence structure in production and in comprehension.

Aphasia↗
PubMedDate not supplied

Functional asymmetry of human prefrontal cortex: encoding and retrieval of verbally and nonverbally coded information.

There are several views about the organization of memory functions in the human prefrontal cortex. One view assumes a process-specific brain lateralization according to different memory subprocesses, that is, encoding and retrieval. An alternative view emphasizes content-specific lateralization of brain systems involved in memory processes. This study addresses this apparent inconsistency between process- and content-specific lateralization of brain activity by investigating the effects of verbal and nonverbal encoding on prefrontal activations during encoding and retrieval of environmental novel sounds using fMRI. An intentional memory task was applied in which subjects were required either to judge the sounds' loudness (nonverbal encoding task) or to indicate whether or not a sound can be verbally described (verbal encoding task). Retrieval processes were examined in a subsequent yes/no recognition test. In the study phase the right posterior dorsolateral prefrontal cortex (PFC) was activated in both tasks. During verbal encoding additional activation of the left dorsolateral PFC was obtained. Retrieval-related fMRI activity varied as a function of encoding task: For the nonverbal task we detected an activation focus in the right posterior dorsolateral PFC whereas an activation in the left dorsolateral PFC was observed for the verbal task. These findings indicate that the right dorsolateral PFC is engaged in encoding of auditory information irrespective of encoding task. The lateralization of PFC activity during retrieval was shown to depend on the availability of verbal codes, with left hemispheric involvement for verbally and right hemispheric activation for nonverbally coded information.

Acoustic Stimulation↗
PubMedDate not supplied

Modularity of object and place memory in children.

The present study investigated modularity of object and place memory in children with the reaction time/accuracy paradigm. The memory task was presented in two spatial arrays, a frame with landmarks and a grid. Modularity was tested using perceptual size judgment (what-interference) and movement direction judgment (where-interference). Latencies of object memory were increased by same-system what-interference in all age groups indicating limited capacity of an object memory system. With respect to accuracy of object and place memory, only young children's performance was susceptible to same-system interference of perceptual judgment.

Age Factors↗