Hot off the presses! Jun 01 Cortex

The Jun 01 issue of the Cortex is now up on Pubget (About Cortex): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Cover Figure
  - Cortex 45(6):e1 (2009)
  
• Editorial Board/Title Page
  - Cortex 45(6):i (2009)
  
• Contents
  - Cortex 45(6):v (2009)
  
• Hartline's limulus
  - Cortex 45(6):695-696 (2009)
  
• Electrophysiological correlates of different anomic patterns in comparison with normal word production
  - Cortex 45(6):697-707 (2009)
  Different forms of anomia are observed in aphasia, which can be related to impaired semantic, lexical or phonological processes. In the present study, we analysed electrophysiological correlates of different patterns of anomia in six aphasic speakers. Event-related potentials (ERPs) were recorded during picture naming in each anomic speaker and in 15 healthy controls. Waveform analysis and temporal segmentation indicated a difference between high and low frequency words in the control group between 270 and 330 msec after picture onset. The ERPs recorded in the patients were compared to the control group. The time-windows of divergent ERP correlates were very similar between successful and erroneous naming, but they were differently distributed in the 6 patients. Two patients with conduction aphasia and impaired phonological encoding had normal electro-cortical activity during the first 300 msec and abnormal patterns between 300 and 450 msec. Two patients with lexical-s! emantic impairment had earlier ERP abnormalities starting immediately after visual processes. The two patients with less severe anomia and preponderance of omission errors displayed abnormal ERPs between 280 and 350 msec. These results indicate that abnormal electro-cortical correlates of anomic profiles can be observed in different time-windows, which seem to correspond to the time course of the impaired encoding processes.
• Serial order short-term memory capacities and specific language impairment: No evidence for a causal association
  - Cortex 45(6):708-720 (2009)
  This study re-explored the nature of verbal short-term memory (STM) deficits in children with specific language impairment (SLI), by distinguishing item and serial order STM processes. Recent studies have shown serial order STM capacity to be a critical determinant of language development, relative to item STM. In Experiment 1, 12 children with SLI, 12 age-matched children and 12 language-matched children were administered serial order recognition and reconstruction tasks. Experiment 2 assessed implicit serial learning abilities via a Hebb learning task. The SLI group showed impaired performance for the serial order reconstruction and recognition tasks, relative to language-matched and/or age-matched control groups. However, normal serial position effects were observed in all SLI children in the serial order reconstruction task, suggesting normal coding of serial position information. Similarly, performance on the Hebb serial learning task was at chronological age appr! opriate levels. Experiment 3 showed that the group differences observed for the serial order STM tasks in Experiment 1 disappeared when the SLI group was compared to a mental age-matched control group. Experiment 4 showed similar performance levels in the SLI group and the mental age-matched control group for a nonword recognition task assessing item STM capacities. This study shows that children with SLI have no specific impairments for serial order and item STM components but that poorer general cognitive efficiency is related to functional limitations in verbal STM tasks. The data are in line with limited information processing accounts of SLI.
• A novel, illustrated questionnaire to distinguish projector and associator synaesthetes
  - Cortex 45(6):721-729 (2009)
  Individual differences in synaesthesic experiences have recently received much interest, with synaesthetes typically being classified as either projectors (seeing colours projected externally in space) or associators (experiencing colours in their "minds eye"). However, the current standard method of ascertaining these differences through self-reported ratings of statements has been found to be unreliable. Here, we report a test–retest comparison of two sequentially presented questionnaires, asking participants to rate how well the depictions reflect their own experiences. The first questionnaire used standard rating statements, while the second presented the synaesthetic experience in a visual, illustrated format. Results from 12 female synaesthetes highlighted the test–retest consistency with the illustrated questionnaire to be significantly higher than statements alone, suggesting that the visual presentation more approximates and reflects the synaesthetic e! xperience. Through doing so, the illustrated questionnaire is considered to enable an accurate and reliable partition of synaesthetes into projectors and associators.
• Leftward motion restores number space in neglect
  - Cortex 45(6):730-737 (2009)
  In the present study, a group of patients with left-sided neglect performed a number comparison task that co-occurred either with coherent motion in different directions or with random motion. Their performance was compared to that of a healthy control group and to a group of patients with right hemisphere damage (RHD) but no signs of neglect. The presence of leftward motion alleviated the difficulties that neglect patients typically show for a number smaller than the reference number 5 (i.e., number 4). Moreover, the standard distance effect was only present when the task co-occurred with leftward motion. These effects were not present in a group of participants with RHD without neglect or in a control group. The present data extend the effects of optokinetic stimulation (OKS) to representational neglect, suggesting that an external redirection of attention by the perception of motion may restore the altered access to the representation of the mental number line in ne! glect.
• Noun and verb differences in picture naming: Past studies and new evidence
  - Cortex 45(6):738-758 (2009)
  We re-examine the double dissociation view of noun–verb differences by critically reviewing past lesion studies reporting selective noun or verb deficits in picture naming, and reporting the results of a new picture naming study carried out with aphasic patients and comparison participants. Since there are theoretical arguments and empirical evidence that verb processing is more demanding than noun processing, in the review we distinguished between cases that presented with large and small differences between nouns and verbs. We argued that the latter cases may be accounted for in terms of greater difficulty in processing verbs than nouns. For the cases reporting large differences between nouns and verbs we assessed consistency in lesion localization and consistency in diagnostic classification. More variability both in terms of diagnostic category and lesion sites was found among the verb impaired than the noun impaired patients. In the experimental study, nine aphasic patients and nine age matched neurologically unimpaired individuals carried out a picture naming study that used a large set of materials matched for age of acquisition and in addition to accuracy measures, latencies were also recorded. Despite the patients' variable language deficits, diagnostic category and the matched materials, all patients performed faster and more accurately in naming the object than the action pictures. The comparison participants performed similarly. We also carried out a qualitative analysis of the errors patients made and showed that different types of errors were made in response to object and action pictures. We concluded that action naming places more and different demands on the language processor than object naming. The conclusions of the literature review and the results of the experimental study are discussed in relation to claims previous studies have made on the basis of the double dissociation found between nouns and verbs. We argue that these claims are only justified when it can be shown that the impairments to the two categories occur for the same underlying reason and that the differences between the two categories are large.
• Neural differences in the processing of true and false sentences: Insights into the nature of 'truth' in language comprehension
  - Cortex 45(6):759-768 (2009)
  The inquiry on the nature of truth in language comprehension has a long history of opposite perspectives. These perspectives either consider that there are qualitative differences in the processing of true and false statements, or that these processes are fundamentally the same and only differ in quantitative terms. The present study evaluated the processing nature of true and false statements in terms of patterns of brain activity using event-related functional-Magnetic-Resonance-Imaging (fMRI). We show that when true and false concept-feature statements are controlled for relation strength/ambiguity, their processing is associated to qualitatively different processes. Verifying true statements activates the left inferior parietal cortex and the caudate nucleus, a neural correlate compatible with an extended search and matching process for particular stored information. In contrast, verifying false statements activates the fronto-polar cortex and is compatible with a ! reasoning process of finding and evaluating a contradiction between the sentence information and stored knowledge.
• Unusual use of objects after unilateral brain damage. The technical reasoning model
  - Cortex 45(6):769-783 (2009)
  It has been suggested that gesture engrams, conceptual knowledge and/or the ability to infer function from structure can support object use. The present paper proposes an alternative view which is based upon the idea that object use requires solely the ability to reason about technical means provided by objects. Technical means are abstract principles which are not linked with any object representation (e.g., cutting involves the opposition between dense and permeable material). The technical reasoning model predicts that the inability to perform technical reasoning should impair performance in any situation requiring the use of objects (in a conventional way or not). Twenty left brain-damaged (LBD) patients, 11 right brain-damaged (RBD) patients and 41 healthy controls were examined on experimental tests assessing the conventional use of objects (e.g., screwing a screw with a screwdriver), conceptual knowledge about object function, pantomime of object use and recogni! tion of object utilization gestures. We also designed the Unusual Use of Objects Test, which demands unusual applications of objects to achieve a purpose for which the usually applied object is not provided (e.g., screwing a screw with a knife). The key findings are that only LBD patients have more difficulties on the Unusual Use of Objects Test than controls or RBD patients, and that the severity of their impairment is correlated with that on conventional use of objects. Correlations with tests assessing conceptual knowledge as well as with tests of pantomime of object use and recognition of object utilization gestures were weaker. These results support the technical reasoning model and question the role of conceptual knowledge and gesture engrams in object use. Since the technical reasoning model also predicts two distinct technical disorders, the discussion focuses on the existence of these disorders in regard to individual performance profiles obtained in the Unusual Us! e of Objects Test.
• Are the same phoneme and lexical layers used in speech production and comprehension? A case-series test of model of aphasic speech production
  - Cortex 45(6):784-790 (2009)
  In this paper, we investigate the claim that although the same lexical units are involved in speech production and comprehension, there are separate input and output phoneme layers (Foygel and Dell, 2000). Data from a case series of aphasic patients are used to test this claim by examining the relationship between performance on a test of picture naming and performance on tests of phonological input. Estimates of each patient's semantic-lexical and phonological impairments in speech production were derived from Foygel and Dell's computational model of picture naming. It was found that the strength of the semantic-lexical impairments in speech production was significantly correlated with performance on auditory comprehension tests. This finding is consistent with the claim that the same lexical units are involved in speech comprehension and production. Conversely, the correlations between the strength of the phonological lesions in speech production and performance on t! ests of phonological input were non-significant, consistent with Foygel and Dell's claim that there are distinct input and output phoneme layers.
• Writing about mirror writing
  - Cortex 45(6):791-792 (2009)