Cortical memory mechanisms and language origins

We have previously proposed that cortical auditory-vocal networks of the monkey brain can be partly homologized with language networks that participate in the phonological loop. In this paper, we suggest that other linguistic phenomena like semantic and syntactic processing also rely on the activation of transient memory networks, which can be compared to active memory networks in the primate. Consequently, short-term cortical memory ensembles that participate in language processing can be phylogenetically tracked to more simple networks present in the primate brain, which became increasingly complex in hominid evolution. This perspective is discussed in the context of two current interpretations of language origins, the "mirror-system hypothesis" and generativist grammar.     

The transition to increased automaticity during finger sequence learning in adult males who stutter

The present study compared the automaticity levels of persons who stutter (PWS) and persons who do not stutter (PNS) on a practiced finger sequencing task under dual task conditions. Automaticity was defined as the amount of attention required for task performance. Twelve PWS and 12 control subjects practiced finger tapping sequences under single and then dual task conditions. Control subjects performed the sequencing task significantly faster and less variably under single versus dual task conditions while PWS' performance was consistently slow and variable (comparable to the dual task performance of control subjects) under both conditions. Control subjects were significantly more accurate on a colour recognition distracter task than PWS under dual task conditions. These results suggested that control subjects transitioned to quick, accurate and increasingly automatic performance on the sequencing task after practice, while PWS did not. Because most stuttering treatment programs for adults include practice and automatization of new motor speech skills, findings of this finger sequencing study and future studies of speech sequence learning may have important implications for how to maximize stuttering treatment effectiveness. Educational objectives: As a result of this activity, the participant will be able to: (1) Define automaticity and explain the importance of dual task paradigms to investigate automaticity; (2) Relate the proposed relationship between motor learning and automaticity as stated by the authors; (3) Summarize the reviewed literature concerning the performance of PWS on dual tasks; and (4) Explain why the ability to transition to automaticity during motor learning may have important clinical implications for stuttering treatment effectiveness.     

Do distractors interfere with memory for study pairs in associative recognition?

In an associative recognition task, distractors generally consist of a rearrangement of the items composing the study pairs. This makes it possible that processing the distractors generates retroactive interference on memory for the study pairs. In Experiment 1, we explored this possibility in ayes/no recognition test concerning previously learned arbitrary associations between visual symbols and auditory syllables. Rearranged pairs had a deleterious impact on the accuracy and the speed of responses to related correct pairs. This effect did not vary as a function of the number of training blocks, and furthermore, in Experiment 2, the same effect was observed for overlearned small multiplication facts. These results suggest that exposure to potentially confounding information generates interference even if this information is known to be incorrect. Some implications are outlined, especially with regard to the widespread use of multiple-choice tests in knowledge evaluation.     

Word frequency and word likeness mirror effects in episodic recognition memory

Estes and Maddox (2002) suggested that the word frequency mirror effect in episodic recognition memory might be due to word likeness rather than to the frequency of experience with a word per se. We examined their suggestion using a factorial manipulation of frequency and neighborhood density, a measure used in lexical memory research to measure orthographic word likeness. For study with no specified task, main effects of density and frequency were in the mirror order, confirming the hypothesized mirror effect of word likeness but not its role in producing the frequency mirror effect. Lexical decision study increased the size of both mirror effects, even though the density manipulation had a negligible effect on lexical decision performance for words. Post hoc analyses showed that neither mirror effect could be explained by differences in lower order measures of word likeness (letter and bigram frequency). The joint orders of frequency and density results were mirrored across new and old conditions in accordance with attention likelihood theory (ALT), but density effects on z-ROC slope suggest that ALT may require extension to accommodate the effect of word likeness on response confidence.     

The validity of the hospital anxiety and depression scale and the geriatric depression scale in Parkinson's disease

We assessed the concurrent validity of the Hospital Anxiety and Depression Scale (HADS) and the Geriatric Depression Scale (GDS) against the Hamilton Rating Scale for Depression (Ham-D) in patients with Parkinson's disease (PD). Forty-six non-demented PD patients were assessed by a neurologist on the Ham-D. Patients also completed four mood rating scales: the HADS, the GDS, the VAS and the Face Scale. For the HADS and the GDS, Receiver Operating Characteristics (ROC) curves were obtained and the positive and negative predictive values (PPV, NPV) were calculated for different cut-off scores. Maximum discrimination between depressed and non-depressed PD patients was reached at a cut-off score of 10/11 for both the HADS and the GDS. At the same cut-off score of 10/11 for both the HADS and the GDS, the high sensitivity and NPV make these scales appropriate screening instruments for depression in PD. A high specificity and PPV, which is necessary for a diagnostic test, was reached at a cut-off score of 12/13 for the GDS and at a cut-off score of 11/12 for the HADS. The results indicate the validity of using the HADS and the GDS to screen for depressive symptoms and to diagnose depressive illness in PD.     

MMPI--2 Code-Type Congruence of Injured Workers

In this study, the authors examined the stability of Minnesota Multiphasic Personality Inventory--2 (J. N. Butcher, W. G. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989) code types in a sample of 94 injured workers with a mean test-retest interval of 21.3 months (SD = 14.1). Congruence rates for undefined code types were 34% for high-point codes, 22% for 2-point codes, and 22% for 3-point codes. The data provide tentative evidence suggesting that defined code types are more stable than undefined code types. Cohen's kappa, a statistic that controls for chance agreement, was calculated for each clinical scale for both 2-point and 3-point code types. Only 2 of the 20 kappa coefficients were not significant at the p = .05 level.