Schizophrenia and semantic aphasia: a clinical comparison

Neuropsychological dimensions related to alterations of verbal self-monitoring neural networks in schizophrenic language: systematic review

Although schizophrenia has traditionally been interpreted as a disorder of thought, contemporary perspectives suggest that it may be more appropriate to conceptualize it as a disorder of language connectivity. The linguistic anomalies present in schizophrenia possess distinctive characteristics that, despite certain connections, are not comparable to aphasic disorders. It is proposed that these anomalies are the result of dysfunctions in verbal self-monitoring mechanisms, which may influence other neuropsychological dimensions. This study set out to examine the neuropsychological dimensions associated with alterations in the neural networks of verbal self-monitoring in schizophrenic language, based on the scientific evidence published to date. Exhaustive searches were conducted in PubMed, Web of Science, and Scopus to identify magnetic resonance studies that evaluated verbal self-monitoring mechanisms in schizophrenia. Of a total of 133 articles identified, 22 were selected for qualitative analysis. The general findings indicated alterations in frontotemporoparietal networks and in systems such as the insula, amygdala, anterior cingulate cortex, putamen, and hippocampus. Despite the heterogeneity of the data, it is concluded that language plays a fundamental role in schizophrenia and that its alterations are linked with other neuropsychological dimensions, particularly emotional and perceptual ones.

Disordered verbalizations in schizophrenia: a speech disturbance or thought disorder?

This research provides empirical data relevant to the long-standing theoretical issue of whether disordered speech in schizophrenia should be viewed as a speech disturbance or a thought disorder. The study analyzed whether schizophrenia patients with disordered speech on one test also show strange nonverbal behavior and unrealistic ideas on other assessments. One hundred eighty-four patients, including 55 schizophrenia patients, were assessed at the acute phase and followed up twice, over 4.5 years. Patients were assessed (1) with a standardized measure that can elicit disordered speech, (2) with a different measure that can elicit an atypical sorting of objects and an intermingling of personal ideas, and (3) for delusions (unrealistic thinking). Schizophrenia patients with disordered speech on the Proverbs Test also (1) sorted objects strangely on the Object Sorting Test (P <.05), (2) showed an intermingling of personal ideas into their thinking (P <.01), and (3) had delusional ideas when assessed at two successive follow-ups over a multiyear period (P <.001). The data suggest that most schizophrenia patients and other psychotic patients with disordered speech also show strange nonverbal behavior and unrealistic ideas/beliefs. These data support a theoretical framework in which disordered speech in schizophrenia and other types of psychotic patients is viewed as not just due to a speech disorder, but is often part of a broader constellation that includes gross reality distortions, strange behavior and ideas, and disordered thinking.

Dissociable processes for learning the surface structure and abstract structure of sensorimotor sequences

A sensorimotor sequence may contain information structure at several different levels. In this study, we investigated the hypothesis that two dissociable processes are required for the learning of surface structure and abstract structure, respectively, of sensorimotor sequences. Surface structure is the simple serial order of the sequence elements, whereas abstract structure is defined by relationships between repeating sequence elements. Thus, sequences ABCBAC and DEFEDF have different surface structures but share a common abstract structure, 123213, and are therefore isomorphic. Our simulations of sequence learning performance in serial reaction time (SRT) tasks demonstrated that (1) an existing model of the primate fronto-striatal system is capable of learning surface structure but fails to learn abstract structure, which requires an additional capability, (2) surface and abstract structure can be learned independently by these independent processes, and (3) only abstract structure transfers to isomorphic sequences. We tested these predictions in human subjects. For a sequence with predictable surface and abstract structure, subjects in either explicit or implicit conditions learn the surface structure, but only explicit subjects learn and transfer the abstract structure. For sequences with only abstract structure, learning and transfer of this structure occurs only in the explicit group. These results are parallel to those from the simulations and support our dissociable process hypothesis. Based on the synthesis of the current simulation and empirical results with our previous neuropsychological findings, we propose a neuro-physiological basis for these dissociable processes: Surface structure can be learned by processes that operate under implicit conditions and rely on the fronto-striatal system, whereas learning abstract structure requires a more explicit activation of dissociable processes that rely on a distributed network that includes the left anterior cortex.

Schizophrenic neologism versus aphasic neologism: characteristics in writings of Japanese schizophrenic patients

Three cases of schizophrenia with ideographic neologisms in Japanese are presented and compared with aphasic neologisms reported in Japanese literature. Schizophrenic neologisms are different from aphasic neologisms in nature. The contrast becomes obvious when both are compared in Japanese writing based on the dual writing system of kanji (Chinese characters, ideogram) and kana (phonetic characters, syllabogram).

Diagnostic validity of a short neurobehavioral test for screening of parietal lobe lesions

Disturbances stemming from lesions of the parietal lobes can produce the most wide-ranging and diagnostically ambiguous symptoms of any of the cortical regions. Currently, parietal assessment and research is hampered by the lack of a specific, brief battery which emphasizes sensory-perceptual rather than cognitive aspects of parietal lobe disease. The Neurological Tests of Parietal Impairment (NTPI) is a battery designed to fulfill this need, providing a broad but brief assessment of major neurobehavioral symptoms of parietal insult. The present study was a preliminary attempt to investigate the diagnostic validity of the NTPI, comparing 7 focal left and 7 focal right parietal lesion cases with 7 focal left and 4 focal right frontal lobe cases, and 5 cases with diffuse cortical disease. The NTPI was found correctly to lateralize right parietal patients and successfully to discriminate them from patients with both right and left frontal lesions on all NTPI subtests except those involving complex receptive speech. Diffuse lesion cases could not be differentiated from parietal patients on the NTPI, as expected. Left parietal patients were not correctly lateralized as effectively as right parietal cases by the NTPI, nor could their performance be differentiated from that of the frontal lesion cases. Possible reasons for this finding were discussed.