An age-related deficit in prefrontal cortical function associated with refreshing information

Older adults are slower than young adults to think of an item they just saw, that is, to engage or execute (or both) the simple reflective operation of refreshing just-activated information. In addition, they derive less long-term memory benefit from refreshing information. Using functional magnetic resonance imaging (fMRI), we found that relative to young adults, older adults showed reduced refresh-related activity in an area of dorsolateral prefrontal cortex (left middle frontal gyrus, Brodmann's Area 9), but not in other refresh-related areas. This provides strong evidence that a frontal component of the circuit that subserves this basic cognitive process is especially vulnerable to aging. Such a refresh deficit could contribute to poorer performance of older than young adults on a wide range of cognitive tasks.     

When looks are everything: appearance similarity versus kind information in early induction

The goal of this research was to examine mechanisms underlying early induction--specifically, the relation between induction and categorization. Some researchers argue that even early in development, induction is based on category-membership information, whereas others argue that early induction is based primarily on similarity. Children 4 and 5 years of age participated in two types of tasks: categorization and induction. Both tasks were performed with artificial animal-like categories in which appearance was pitted against category membership. Although the children readily acquired category-membership information and subsequently used this information in categorization tasks, they ignored category membership during the induction task, relying instead on the appearance of items. These results support the idea that early in development, induction is similarity based.     

Memory for people and their actions: further evidence for an age-related associative deficit

The associative deficit hypothesis (M. Naveh-Benjamin, 2000) attributes age-related memory deficits to the inability to encode and retrieve bound units of information. The present experiment extended this deficit to a new form of stimuli, dynamic displays of people and their performance of everyday actions. Older and younger adults viewed a series of brief video clips, each showing a different person performing a different action, and were tested over memory for individual people, individual actions, and the person-action combinations. Older adults did exhibit an associative deficit, and this was related to an increased proportion of false alarms on the associative test.     

Modelling age-related changes in information processing

Researchers in cognitive ageing seldom take advantage of explicit quantitative models of information processing to account for age differences in cognition. Where quantitative models have been used, these models typically remain silent about the details of information processing. The lack of explicit cognitive models has consequences for the interpretation of a number of empirical results. Using a specific class of models called random walk models, I review evidence showing that the empirical relations taken as support for global age-related changes are consistent with a number of possible age effects on information processing. In addition, I demonstrate that these models can be used to account for age differences within the context of individual experiments and such modelling has important implications for the interpretation of age differences in performance.     

Conditioning decorticate canines in Culler's laboratory: some reflexions and second thoughts

Rapid expansion and increasing specialization, characteristics of the progress of science in general, occurred in physiological psychology in the 1930s. The development of E. A. K. Culler's laboratory at the University of Illinois may be representative of this phenomenon. Controversial problems raised during the writer's participation in the laboratory, such as conditioning in the decorticate and distribution and function of the cerebral auditory system, are considered from a present-day perspective. It is suggested that conceptual constraints imposed by some outstanding leaders, as illustrated with Pavlov, may no longer play the dominant role as described earlier in psychology's growth.     

Predictors of suicidal thoughts: Mood instability versus neuroticism

The personality trait neuroticism predicts depression and suicidal thoughts. Neuroticism is also linked to mood instability (MI)¹ that is common in patients with depression. This study investigated (a) whether MI predicts suicidal thoughts in depressed patients and (b) the relationship of MI to neuroticism. All 129 patients with Major Depression (MINI interview) were assessed on MI (Affective Lability Scale), neuroticism (Short Eysenck Neuroticism Scale), depression (Beck Depression Inventory), and suicidal thoughts (Beck Scale for Suicidal Ideation). Participants also completed the Perceived Stress Scale, Mood Disorder Questionnaire and five clinical questions on MI. Factor analysis of the Eysenck Neuroticism Scale revealed unstable moods as one of three main factors. Only depression severity and MI predicted suicidal thoughts once other variables including neuroticism were controlled. Mediation analyses showed that MI mediated the relationship between neuroticism and suicidal thoughts. These results suggest that MI as measured by the Affective Lability Scale typifies the type of depression that predicts suicidal thoughts and that MI may be more directly associated with suicidal thoughts than neuroticism. This demonstrates the clinical value of assessing MI rather than neuroticism in the treatment of patients with depression with suicidal thoughts.     

Selective deficit of conceptual structures in aphasia: Class versus thematic relations

Conceptual structures in aphasia were investigated by means of a nonverbal test. The understanding of class and thematic relationships was demonstrated to be selectively impaired according to varieties of aphasic deficit. Broca's aphasics showed difficulty evaluating a thematic relationship and did not differ from normal controls as far as class relationships were concerned. The opposite happened for Wernicke's aphasics whose defect seems to be selectively restricted to class relationships.     

Syntactic loss versus processing deficit: an assessment of two theories of agrammatism and syntactic comprehension deficits

This research evaluated Grodzinsky's (1984, 1986a) syntactic loss and Kolk and van Grunsven's (1985) working memory impairment explanations of syntactic comprehension deficits in agrammatic aphasics. Four aphasic patients were evaluated who showed different patterns of impairment on morphological and structural aspects of production. The comprehension tasks compared performance on full and truncated passive sentences. The syntactic loss hypothesis predicted worse performance on truncated than full passives, while the working memory deficit hypothesis predicted the reverse. Neither hypothesis was supported, as the patients performed at a similar level on both types of passives. In addition, there was little relation between the patients' production indices and their comprehension level. The results argue against any global theory of agrammatism that attempts to attribute all agrammatic speech and co-occurring syntactic comprehension deficits to the same source.     

Heuristics versus direct calculation,and age-related differences in multiplication: an evidence accumulation account of plausibility decisions in arithmetic

We offer a new theoretical angle for cognitive arithmetic, which is that evidence accumulation may play a role in problem plausibility decisions. We build upon previous studies that have considered such a hypothesis, and here formally evaluate the paradigm. We develop the finding that performance differences, due to variations in strategy use and aging effects, can indeed be reasonably explained through these accumulation-to-bound cognitive models. Results suggest that these models may be effectively used to learn more about the underlying cognitive processes. In this study, we modelled young (18–24) and older (68–82) adults’ solution times in performing arithmetic verification (e.g. whether 8?×?5?=?41 is true/false). The domain-relevant factors in strategy use (problem-verification heuristics) and aging differences (older/younger adult groups) were analyzed by a response process model of the latency data, that is fit by participant and item. Lower thresholds accounted for the faster response times (RTs) for problems solved with heuristics (arithmetic rule-violation checking strategies), as opposed to problems solved by calculation approaches. A more rapid accumulation accounted for faster RTs on problems in which two arithmetic rules were violated (strategy combination) rather than one. Third, higher thresholds (i.e. preferring to have greater certainty before responding) accounted for older adults’ slower speed. These findings are in support of accumulation models being relevant for more complex cognitive tasks, as well as to account for the age-related differences therein.     

Maintenance versus manipulation of information held in working memory: an event-related fMRI study.

One model of the functional organization of lateral prefrontal cortex (PFC) in primates posits that this region is organized in a dorsal/ventral fashion subserving spatial and object working memory, respectively. Alternatively, it has been proposed that a dorsal/ventral subdivision of lateral PFC instead reflects the type of processing performed upon information held in working memory. We tested this hypothesis using an event-related fMRI method that can discriminate among functional changes occurring during temporally separated behavioral subcomponents of a single trial. Subjects performed a delayed-response task with two types of trials in which they were required to: (1) retain a sequence of letters across the delay period (maintenance) or (2) reorder the sequence into alphabetical order across the delay period (manipulation). In each subject, activity during the delay period was found in both dorsolateral and ventrolateral PFC in both types of trials. However, dorsolateral PFC activity was greater in manipulation trials. These findings are consistent with the processing model of the functional organization of working memory in PFC.     

Emotion recognition in schizophrenia: further investigation of generalized versus specific deficit models

In this study, the authors examined the nature of emotion perception in schizophrenia. Two samples of people with schizophrenia, one receiving acute care for a recent exacerbation of symptoms and the other receiving extended care, were compared with a nonclinical control group on emotion perception and general perception measures. The nonclinical control group obtained the highest scores on all of the study measures, and the acutely ill group obtained the lowest scores. Furthermore, the acutely ill sample had a specific deficit in emotion perception that remained present after controlling for performance on the general perception tasks. Conversely, the deficits in emotion discrimination in the extended-care sample reflected generalized poor performance. Differences in performance on the emotion identification task between the 2 clinical groups were reduced when controlling for active symptoms.