Reading ability is negatively related to Stroop interference

Stroop interference is often taken as evidence for reading automaticity even though young and poor readers, who presumably lack reading automaticity, present strong interference. Here the relationship between reading skills and Stroop interference was studied in a 7th-grade sample. Greater interference was observed in children diagnosed with reading disability (dyslexia) than in unimpaired children. Moreover, poorer reading skills were found to correlate with greater Stroop interference in the general school population. In correlation and regression analyses, interference was primarily associated with reading speed, with an additional unique contribution of reading accuracy. Color naming errors were few and not comparably related to reading skills. The relation of reading skill to Stroop interference was examined in computational modeling simulations. The production model of Roelofs [Roelofs, A. (2003). Goal-referenced selection of verbal action: modeling attentional control in the Stroop task. Psychological Review, 110, 88-125], in which interference is primarily due to word stimuli having direct access to word form encoding whereas color naming must pass through concept activation and lemma selection, was found to account well for the human data after imposing covariation constraints on parameters controlling word processing and blocking latency, in modifications not affecting the model's previous fit to other data. The connectionist model of Cohen, Dunbar, and McClelland [Cohen, J. D., Dunbar, K., & McClelland, J. L. (1990). On the control of automatic processes: a parallel distributed processing account of the Stroop effect. Psychological Review, 97, 332-361], in which interference is caused by differential route strength, implementing an automaticity account, approximated the observed patterns with network-wide parameter manipulations not specific to reading, such as processing speed and response threshold, likely to affect previously optimized performance. On the basis of the empirical and modeling data we argue for a direct link between reading skill and interference, beyond the effects of executive functioning.     

Statistical learning is related to reading ability in children and adults

There is little empirical evidence showing a direct link between a capacity for statistical learning (SL) and proficiency with natural language. Moreover, discussion of the role of SL in language acquisition has seldom focused on literacy development. Our study addressed these issues by investigating the relationship between SL and reading ability in typically developing children and healthy adults. We tested SL using visually presented stimuli within a triplet learning paradigm and examined reading ability by administering the Wide Range Achievement Test (WRAT-4; Wilkinson & Robertson, 2006). A total of 38 typically developing children (mean age of 9;5 years, range 6;4-12;5) and 37 healthy adults (mean age of 21 years, range 18-34) were assessed. In children, SL was significantly related to reading ability. Importantly, this relationship was independent of grade and also age. The adult data, too, revealed that SL was significantly related to reading ability. A regression analysis of the combined child and adult data revealed that SL accounted for a unique amount of variance in reading ability, after age and attention had been taken into consideration. For the first time, this study provides empirical evidence that a capacity for more effective SL is related to higher reading ability in the general population.     

Multidimensional assessment of empathic abilities in patients with insular glioma

Recent studies have provided evidence that there are two possible systems for empathy: affective empathy (AE) and cognitive empathy (CE). Neuroimaging paradigms have proven that the insular cortex is involved in empathy processing, particularly in AE. However, these observations do not provide causal evidence for the role of the insula in empathy. Although impairments in empathy have been described following insular damage in a few case studies, it is not clear whether insular cortex is involved in CE and whether these two systems are impaired independently or laterally in patients with insular gliomas. In this study, we assessed 17 patients with an insular glioma, 17 patients with a noninsular glioma, and 30 healthy controls using a method that combined a self-report empathy questionnaire with the emotion recognition task, assessment of empathy for others’ pain, and the emotional perspective-taking paradigm. We found that patients with an insular glioma had lower scores for empathic concern and perspective taking than did either healthy controls or lesion controls. The patients’ abilities to recognize facial emotions, perceive others’ pain, and understand the emotional perspectives of others were also significantly impaired. Furthermore, we did not observe a laterality effect on either AE or CE among those with insular lesions. These findings revealed that both AE and CE are impaired in patients with an insular glioma and that the insular cortex may be a central neuroanatomical structure in both the AE and CE systems.     

Children with autism are impaired in the understanding of teaching

Children learn novel information using various methods, and one of the most common is human pedagogical communication or teaching – the purposeful imparting of information from one person to another. Neuro‐typically developing (TD) children gain the ability to recognize and understand teaching as a core method for acquiring knowledge from others. However, it is not known when children with Autism Spectrum Disorder (ASD) acquire the ability to recognize and understand teaching. This study (total N = 70) examined whether children with ASD recognize the two central elements that define teaching: (1) that teaching is an intentional activity; and (2) that teaching requires a knowledge difference between teacher and learner. Theory of mind understanding was also tested. Compared to individually matched TD children, high cognitively functioning children with ASD were impaired in their comprehension of both components of teaching understanding, and their performance was correlated with theory of mind understanding. These findings could have broad implications for explaining learning in children with autism, and could help in designing more effective interventions, which could ultimately lead to improved learning outcomes for everyday life skills, school performance, health, and overall well‐being.     

Memory deficits are associated with impaired ability to modulate neuronal excitability in middle-aged mice

Normal aging disrupts hippocampal neuroplasticity and learning and memory. Aging deficits were exposed in a subset (30%) of middle-aged mice that performed below criterion on a hippocampal-dependent contextual fear conditioning task. Basal neuronal excitability was comparable in middle-aged and young mice, but learning-related modulation of the post-burst afterhyperpolarization (AHP)—a general mechanism engaged during learning—was impaired in CA1 neurons from middle-aged weak learners. Thus, modulation of neuronal excitability is critical for retention of context fear in middle-aged mice. Disruption of AHP plasticity may contribute to contextual fear deficits in middle-aged mice—a model of age-associated cognitive decline (AACD).Plasticity of intrinsic neuronal excitability increases the overall storage capacity of neurons and therefore likely plays a critical role in learning and memory (Zhang and Linden 2003). Increased neuronal excitability via reductions of the post-burst afterhyperpolarization (AHP) is hypothesized as a general mechanism underlying learning and memory tasks (Disterhoft et al. 1986; Disterhoft and Oh 2006). The AHP serves to limit subsequent firing in response to excitation (Madison and Nicoll 1984; Lancaster and Adams 1986; Storm 1990; Sah and Bekkers 1996). Generally speaking, the size of the AHP is inversely related to neuronal excitability, and the measurement of the AHP is routinely used as an index of neuronal excitability.Our laboratory and others have shown that AHP reductions are observed in hippocampal neurons from animals that learn hippocampal-dependent tasks including trace eyeblink conditioning in rabbit and rat (de Jonge et al. 1990; Moyer Jr et al. 1996, 2000; Kuo 2004) and spatial water maze in rat and mouse (Oh et al. 2003; Tombaugh et al. 2005; Ohno et al. 2006b). Learning-related reductions in the AHP have also been observed in cortical neurons following odor discrimination (Saar et al. 1998) and extinction learning (Santini et al. 2008). In vitro, activity-dependent plasticity of the AHP is induced using physiologically relevant stimuli (Kaczorowski et al. 2007). Because the AHP serves to limit subsequent firing, learning-related reductions in the AHP are poised to facilitate mechanisms crucial for information storage, such as long-term potentiation (LTP), synaptic integration (Sah and Bekkers 1996), metaplasticity (Le Ray et al. 2004), and spike-timing dependent plasticity (STDP) (Le Ray et al. 2004).Hippocampal neurons from naïve aged rodents and rabbits show a decrement in basal excitability evidenced by a robust enhancement of the AHP (Landfield and Pitler 1984; Moyer Jr et al. 1992, 2000; Oh et al. 1999; Kumar and Foster 2002, 2004; Power et al. 2002; Hemond and Jaffe 2005; Murphy et al. 2006b; Gant and Thibault 2008). Enhancement of the AHP in hippocampal neurons in aged animals correlates with impaired performance on learning paradigms that depend on a functional hippocampus, such as trace eyeblink and spatial water maze (Moyer Jr et al. 2000; Tombaugh et al. 2005; Murphy et al. 2006a). Pharmaceuticals aimed at reducing the AHP and increasing basal excitability (Moyer Jr et al. 1992; Moyer Jr and Disterhoft 1994) have been successful at restoring performance of aged rats on trace eyeblink conditioning (Deyo et al. 1989; Straube et al. 1990; Kowalska and Disterhoft 1994). Interestingly, AHPs from neurons recorded from aged learners are indistinguishable from young learners; both are reduced compared to that of aged weak-learners (Moyer Jr et al. 2000; Tombaugh et al. 2005). These data suggest that mechanisms that permit learning-related modulation of the AHP are also critical determinants of learning abilities in an aged population. To date, age-related impairments in hippocampal-dependent tasks and biophysical alterations in hippocampal neurons have largely focused on studies that compare animals at extreme ends of the aging spectrum.In an effort to better understand physiological changes that underlie the onset of early cognitive decline, the development of rodent models of “normal” age-associated cognitive decline (AACD), as well as mild cognitive impairment (MCI), is critical (Pepeu 2004). Therefore, we set out to characterize the development of age-related deficits indicative of hippocampal dysfunction in middle-aged C57Bl6/SJL mice and to examine the biophysical changes in hippocampal neurons that accompany such deficits.Recently, age-related deficits in contextual fear memory following trace fear conditioning were reported in a subset of middle-aged rats (Moyer Jr and Brown 2006). Because the dorsal hippocampus is critical for trace and contextual fear conditioning in mice and rats (McEchron et al. 1998; Chowdhury et al. 2005; Misane et al. 2005), trace fear conditioning is an ideal paradigm for exploring cellular mechanisms that underlie early-age-related cognitive decline.Here we investigate the effects of “early” aging on trace fear conditioning by comparing performance outcomes of young (2 mo, n = 7; and 4 mo, n = 8) and middle-aged (8 mo, n = 22) male C57/SJL F1 hybrid mice. Mice were trained and tested singly, and the experimenter was blind to the training and retention status of the mice. All animal procedures were approved by the Northwestern University Animal Care and Use Committee. Preliminary data were reported previously (Kaczorowski 2006).To assess hippocampal function with aging, young and middle-aged mice were trained on a trace fear conditioning task followed by retention tests of the auditory conditioned stimulus (CS) and contextual CS memory. The basic protocol for trace fear conditioning has been described previously (Ohno et al. 2006a). Mice were trained in a Plexiglas conditioning chamber with a stainless-steel floor grid used for shock delivery. After the baseline period (150 sec), mice received four pairings of the CS (tone; 15 sec, 3 kHz, 75 dB) and US (shock; 1 sec, 0.7 mA). The CS and unconditioned stimulus (US) were separated by a 30-sec empty trace interval. The intertrial interval was set at 210 ± 10 sec. The training chamber was wiped with 95% ethyl alcohol, illuminated with a 10-W bulb in an otherwise dark room, and provided with 65-dB white noise to make it distinct. During training on trace fear conditioning, no effect of age was observed on measures of baseline freezing (F_(2,34) = 2.0, P = 0.15), the expression of freezing during tone (F_(2,34) = 0.6, P = 0.6), or post-shock freezing (F_(2,34) = 0.2, P = 0.8), suggesting that middle-aged and young mice do not differ in measures of anxiolysis or expression of behavioral freezing (measured index of fear) (Fig. 1A).Open in a separate windowFigure 1.Onset of early aging deficits in 8-mo-old middle-aged mice. (A) Baseline (BL) freezing and auditory CS freezing during trace fear conditioning was similar between young (2 mo and 4 mo) and middle-aged (8 mo) mice. (B1) Mean baseline freezing and retention of the auditory CS memory (tones 1–4) were comparable in young (2 mo and 4 mo) and middle-aged (8 mo) mice. (B2) Middle-aged mice showed a significant decrease in freezing compared to young (2 mo and 4 mo) mice when exposed to the original context chamber where they had been trained 1 d earlier; (*) P < 0.05.Retention of the auditory CS:US memory was tested 24 h later in a novel context that differed in its location, size, scent, lighting, background noise, and flooring (bedding) compared to the training chamber. Data from three mice (one young, two middle-aged) were excluded because of video malfunction. Following a 150-sec baseline, mice received four presentations of the tone CS in the absence of footshock. Neither baseline freezing (F_(2,31) = 2.6, P = 0.1) nor conditional freezing in response to the tone CS (F_(2,31) = 1.6, P = 0.2) differed between young and middle-aged mice (Fig. 1B1). Thus, retention of the auditory CS following trace fear conditioning was intact in middle-aged compared to young mice. Although deficits in retention of auditory trace fear have been reported in aged mice and rats (Blank et al. 2003; McEchron et al. 2004; Villarreal et al. 2004), the results herein agree with report of intact trace fear memory in middle-aged rats (Moyer Jr and Brown 2006).One hour after this testing, retention of the contextual fear memory was assessed by placing mice in the original context (in the absence of the tone and footshock) and measuring freezing for 10 min. A subtle but significant difference in freezing was observed as a function of age (F_(2,31) = 4.3, P = 0.02; Fig. 1B ​2).2). A student''s post-hoc t-test revealed that mean freezing (collapsed across 10 min) of middle-aged mice was reduced compared to 2-mo (P < 0.05) and 4-mo (P < 0.05) young mice. Contextual fear memory deficits have been similarly reported in aged mice (Fukushima et al. 2008). Studies that failed to observe contextual fear deficits in aged (>18 mo) mice may result from a floor effect because young mice showed weak conditioning to the context (∼30% freezing) (Feiro and Gould 2005; Gould and Feiro 2005) or employment of delay (Corcoran et al. 2002; Feiro and Gould 2005; Gould and Feiro 2005) compared to trace procedures (Moyer Jr and Brown 2006). Although differences in experimental parameters are plausible, heterogeneity in the performance of aged mice may make detection of age-related impairments difficult owing to increased variability.Open in a separate windowFigure 2.Selective deficits on retention of contextual fear in middle-aged weak-learner mice. (A,B) Summary plot and histogram show young mice (100%, n = 6) at 2 mo of age showed robust recall of contextual fear memory (range 75%–99%) with mean and standard deviation (SD) of 91% ± 10%, whereas retention of middle-aged mice (n = 21) varied to a much greater extent (range 21%–95%; M, SD = 74% ± 19%). Distribution of middle-aged mice relative to their mean percent freezing shows two distinct populations. Middle-aged mice with freezing levels less than 3 SD from the mean freezing in young wild-type (WT) mice (61%, dashed line) were characterized as having weak contextual fear memory (weak learners) and those with freezing levels ≥62% as having strong contextual fear memory (learners). (C) Baseline (BL) freezing, expression of post-shock freezing and freezing during retention tests for auditory CS and trace CS memories, were comparable in both weak-learners and learners. (D) Selective deficits in retention of contextual fear memories were observed in middle-aged weak learners as compared to middle-aged learners; (*) P < 0.05.Previous studies in the rat report heterogeneity in spatial water maze and contextual fear conditioning in middle-aged and/or aged rats compared to young animals (Fischer et al. 1992; Wyss et al. 2000; Moyer Jr and Brown 2006). Therefore, we determined if middle-aged impairments of context fear (Fig. 2A) were driven by a subset of impaired mice. The degree of age-related impairment in each middle-aged mouse was determined by comparison to a reference group of young mice tested concurrently (shown in Fig. 1). The behavioral criterion for retention of contextual fear in middle-aged mice was set at 61%, which was 3 standard deviations (SD) below the mean freezing in young mice (mean and SD, 91% ± 10%; Fig. 1). A bimodal distribution of freezing of middle-aged mice was observed (Fig. 2B), where 70% of middle-aged mice performed above criterion and were labeled learners (n = 14), and 30% of middle-aged mice performed below criterion and were labeled as weak learners (n = 6). Comparison on measures of baseline freezing (F_(1,18) = 1.8, P = 0.2) and expression of post-shock freezing (F_(1,18) = 2.1, P = 0.2) revealed no differences between the groups during auditory trace fear training (Fig. 2C). Similarly, no differences in baseline freezing (F_(1,18) = 0.03, P = 0.9) or acquisition/recall of conditioned auditory trace fear (tone, F_(1,18) = 0.08, P = 0.8; trace, F_(1,18) = 2.4, P = 0.1) were observed 24 h later during retention tests. Thus, deficits ascribed to middle-aged weak learners were limited to contextual processing/retention, where middle-aged weak learners responded to the contextual CS with significantly lower levels of freezing compared to middle-aged learners (F_(1,18) = 47, P = 0.001; Fig. 2D). To summarize, we found that onset of cognitive decline in the C56Bl6/SJL mice was first apparent in a subset of middle-aged mice. Middle-aged weak learners showed a mild but specific deficit in hippocampal-dependent contextual learning/memory (spatial learning) but not hippocampal-dependent auditory trace learning/memory (temporal learning), assessed following trace fear conditioning.Given that contextual fear deficits occurred in a subset of middle-age mice, we were able to directly assess age-related alterations in excitability and AHP plasticity in CA1 neurons as they relate to learning abilities (learners vs. weak learners). Within 1 h of cessation of behavioral tests, middle-aged learners and weak learners were decapitated under deep halothane anesthesia and their brains quickly removed and placed into ice-cold artificial cerebral spinal fluid (aCSF): 125 mM NaCl, 25 mM glucose, 25 mM NaHCO₃, 2.5 mM KCl, 1.25 mM NaH₂PO₄, 2 mM CaCl₂, 1 MgCl₂ (pH 7.5, bubbled with 95%O₂/5%CO₂). Naïve mice were removed from their home cage and underwent identical decapitation procedures. Slices (300 μm) of the dorsal hippocampus and adjacent cortex were made using a Leica vibratome. The slices were first incubated for 30 min at 34°C in bubbled aCSF, and held at room temperature in bubbled aCSF for 1–4 h before use. Recording electrodes prepared from thin-walled capillary glass were filled with potassium methylsulfate-based internal solution and had a resistance of 5–6 MΩ.Whole-cell current-clamp recordings were performed on CA1 hippocampal pyramidal neurons of middle-aged learners (n = 36, 14 mice) and weak-learners (n = 15, 6 mice), as well as middle-aged naïve mice (n = 35 cells, 18 mice). Neuronal excitability was compared by measuring the post-burst AHP generated by 25 action potentials at 50 Hz (Fig. 3A), a stimulus shown to reliably evoke an AHP of sizable—but not maximal—amplitude from hippocampal neurons of mice (Ohno et al. 2006b). A significant difference in the peak amplitude of the AHP from learners, weak learners, and naïve mice was observed (F_(2,83) = 5, P < 0.01). Because the peak AHP and sAHP amplitudes did not differ between neurons from weak-learners and naïve mice (Fig. 3B). No differences in membrane resistance (F_(2,83) = 1.6, P = 0.2) or action potential properties, elicited using a brief (2 msec) near threshold current step (pA), were observed (Open in a separate window^aP < 0.05 compared to Weak L.^bP < 0.05 compared to Naïve.^cP < 0.05 compared to Pooled.Open in a separate windowFigure 3.Learning-related AHP plasticity is impaired in middle-aged weak-learner mice. (A) Representative traces showing the sAHP is reduced in neurons from (black) middle-aged learners compared to (blue) weak-learner mice and (gray) naïve mice. (Inset) The medium AHP (mAHP) of neurons from (black) learner mice was decreased compared to (blue) weak-learner mice and (gray) naïve mice. (B) No differences in the AHP from naïve and weak learners were observed; therefore, their data were pooled, and mean AHP was plotted by time on a log scale. (Inset) The mean amplitude of the peak AHP (1 msec) and sAHP (600 msec) was significantly reduced in neurons from learners compared to AHPs from weak learners and naïve labeled control; (*)P < 0.05.The results presented here are important in two respects. First, we demonstrate that the successful acquisition and recall of trace fear conditioning results in a significant reduction in the AHP in CA1 hippocampal neurons from the mouse. Our data are similar to previous reports showing learning-related reductions of the AHP in hippocampal neurons following training on hippocampal-dependent tasks (Disterhoft and Oh 2007) and thus strengthen the case for neuronal excitability change as a general mechanism underlying hippocampal-dependent learning. Second, we demonstrate that the onset of age-related cognitive decline in the C56Bl6/SJL mouse (termed “weak learners”) first manifests as a specific deficit in spatial associative learning in a subset of middle-age mice. These data, combined with a previous report from middle-aged rats (Moyer Jr and Brown 2006), suggest that initiation of age-related hippocampal dysfunction results in specific spatial—as opposed to temporal—deficits in associative learning and memory during middle age. By combining trace fear conditioning with whole-cell patch-clamp recordings in middle-aged mice, we revealed that “early” age-related impairments in spatial associative learning—like those in the aged hippocampus (Tombaugh et al. 2005)—result in part from an impairment of AHP plasticity of hippocampal neurons. Because AHP reductions are poised to facilitate mechanisms crucial for information storage, it is interesting that trace fear conditioning facilitates the long-term potentiation (LTP) of field excitatory postsynaptic potentials in the CA1 region of the rat hippocampus (Song et al. 2008).Generally speaking, both LTP and activation of AHP currents (I_AHP and sI_AHP) are sensitive to changes in intracellular Ca²⁺ (Storm 1990; Sah 1996; Malenka and Nicoll 1999). Thus, dysregulation of Ca²⁺ homeostasis in the hippocampus of middle-aged rats via enhancement of Ca²⁺-induced Ca²⁺ release (CICR) is an important finding (Gant et al. 2006). Age-related enhancement of Ca²⁺-dependent AHPs has been shown to raise the threshold for induction of LTP (Kumar and Foster 2004). These data support our hypothesis that impairments in contextual fear reported herein, as well as deficits in spatial water maze reported in middle-aged rats (Frick et al. 1995; Markowska 1999; Kadish et al. 2009), result from dysfunction of AHP plasticity.Studies in middle-aged mice have important implications for the treatment of “normal” age-associated cognitive decline (AACD), as well as mild cognitive impairment (MCI) (Pepeu 2004). Further studies aim to examine alterations in cholinergic function in our middle-aged mouse model, as the cholinergic agonist carbachol suppressed the AHP in neurons from naïve middle-aged mice (Supplemental Fig. 1). Activation of cholinergic receptors shape neuronal excitability and synaptic throughput (Tai et al. 2006) through multiple Ca²⁺-dependent processes (Gahwiler and Brown 1987; Tai et al. 2006). Restoration of cholinergic function has been shown to rescue deficits on hippocampal-dependent tasks in aged rodent and mouse models of Alzheimer''s disease (AD) (Disterhoft and Oh 2006), as well as in human AD patients (Cummings et al. 1998; Morris et al. 1998; Pettigrew et al. 1998), and therefore is a potential target aimed at the rescue of early age-related cognitive decline.     

Auditory repetition priming is impaired in pure alexic patients

Alexia without agraphia, or "pure" alexia, is an acquired impairment in reading that leaves writing skills intact. Repetition priming for visually presented words is diminished in pure alexia. However, it is not possible to verify whether this priming deficit is modality-specific or modality independent because reading abilities are compromised. Hence, auditory repetition priming was assessed with lexical decision and word stem completion tasks in pure alexic patients with lesions in left inferior temporal-occipital cortex and the splenium. Perceptually based, modality-specific priming models predict intact auditory priming, since auditory association cortex is spared in the patients. Alternatively, modality-independent models, which suggest that priming reflects the temporary modification of an amodal system, might predict impairments. Baseline performance was matched in the patients and controls, although lexical decision priming measures showed an interaction between group and repetition lag. The patients showed intact immediate priming but significantly less priming than controls at longer delays. Furthermore, word stem completion priming was abolished in the patients. One explanation for the deficit is that left inferior temporal-occipital cortex supports amodal aspects of priming, as suggested by recent neuroimaging results. Another possibility is that long-term auditory priming relies on covert orthographic representations which were unavailable in the patients. The results provide support for interactive models of word identification.     

Activity engagement is related to level, but not change in cognitive ability across adulthood

It is unclear whether the longitudinal relation between activity participation and cognitive ability is due to preserved differentiation (active individuals have higher initial levels of cognitive ability), or differential preservation (active individuals show less negative change across time). This distinction has never been evaluated after dividing time-varying activity into its two sources of variation: between-person and within-person variability. Further, few studies have investigated how the association between activity participation and cognitive ability may differ from early to older adulthood. Using the PATH Through Life Project, we evaluated whether between- and within-person variation in activity participation was associated with cognitive ability and change within cohorts aged 20-24 years, 40-44 years, and 60-64 years at baseline (n = 7,152) assessed on three occasions over an 8-year interval. Multilevel models indicated that between-person differences in activity significantly predicted baseline cognitive ability for all age cohorts and for each assessed cognitive domain (perceptual speed, short-term memory, working memory, episodic memory, and vocabulary), even after accounting for sex, education, occupational status, and physical and mental health. In each case, greater average participation was associated with higher baseline cognitive ability. However, the size of the relationship involving average activity participation and baseline cognitive ability did not differ across adulthood. Between-person activity and within-person variation in activity level were both not significantly associated with change in cognitive test performance. Results suggest that activity participation is indeed related to cognitive ability across adulthood, but only in relation to the starting value of cognitive ability, and not change over time.     

CANTAB explicit memory is less impaired in addicted schizophrenia patients

It has been suggested that in order to sustain the lifestyle of substance abuse, addicted schizophrenia patients would have less negative symptoms, better social skills, and less cognitive impairments. Mounting evidence supports the first two assumptions, but data lack regarding cognition in dual diagnosis schizophrenia. Seventy-six schizophrenia outpatients (DSM-IV) were divided into two groups: with (n = 44) and without (n = 32) a substance use disorder. Motor speed and visuo-spatial explicit memory were investigated using CANTAB. As expected, dual diagnosis patients showed a better cognitive performance. Our results suggest either that substance abuse relieves the cognitive deficits of schizophrenia or that the patients with less cognitive deficits are more prone to substance abuse.     

Studying social cognition in patients with schizophrenia and patients with frontotemporal dementia: theory of mind and the perception of sarcasm

We investigated social cognition and theory of mind in patients with schizophrenia and in patients with frontotemporal dementia in order to elucidate the cognitive mechanisms involved in the breakdown of these skills in psychiatric and neurological patients. Our tasks included videotaped scenarios of social interactions depicting sincere, sarcastic and paradoxical remarks, as well as lies. We found impaired performance of the schizophrenia group on all theory of mind conditions despite their intact understanding of sincere statements. In contrast, the FTD group performed poorly only when they had to rely on paralinguistic cues indicating sarcasm or lies, and not on paradoxical remarks or sarcasm when given additional verbal cues. Our findings suggest that, while current deficits in social and interpersonal functioning in patients with FTD may reflect a decrement in previously acquired skills, similar deficits in patients with schizophrenia may reflect an altogether inadequately learned process.     

Athletic background is related to superior trunk proprioceptive ability,postural control,and neuromuscular responses to sudden perturbations

Trunk motor control is essential for athletic performance, and inadequate trunk motor control has been linked to an increased risk of developing low back and lower limb injury in athletes. Research is limited in comparing relationships between trunk neuromuscular control, postural control, and trunk proprioception in athletes from different sporting backgrounds. To test for these relationships, collegiate level long distance runners and golfers, along with non-athletic controls were recruited. Trunk postural control was investigated using a seated balance task. Neuromuscular control in response to sudden trunk loading perturbations was measured using electromyography and kinematics. Proprioceptive ability was examined using active trunk repositioning tasks. Both athlete groups demonstrated greater trunk postural control (less centre of pressure movement) during the seated task compared to controls. Athletes further demonstrated faster trunk muscle activation onsets, higher muscle activation amplitudes, and less lumbar spine angular displacement in response to sudden trunk loading perturbations when compared to controls. Golfers demonstrated less absolute error and variable error in trunk repositioning tasks compared to both runners and controls, suggestive of greater proprioceptive ability. This suggests an interactive relationship between neuromuscular control, postural control, and proprioception in athletes, and that differences exist between athletes of various training backgrounds.     

Sensitivity to stimulus similarity is associated with greater sustained attention ability

Sustained attention is critical for tasks where perceptual information must be continuously processed, like reading or driving; however, the cognitive processes underlying sustained attention remain incompletely characterized. In the experiments that follow, we explore the relationship between sustaining attention and the contents and maintenance of task-relevant features in an attentional template. Specifically, we administered the gradual onset continuous performance task (gradCPT), a sensitive measure of sustained attention, to a large web-based sample (N>20,000) and a smaller laboratory sample for validation and extension. The gradCPT requires participants to respond to most stimuli (city scenes – 90 %) and withhold to rare target images (mountain scenes – 10 %). By using stimulus similarity to probe the representational content of task-relevant features—assuming either exemplar- or category-based feature matching—we predicted that RTs for city stimuli that were more “mountain-like” would be slower and “city-like” mountain stimuli would elicit more erroneous presses. We found that exemplar-based target-nontarget (T-N) similarity predicted both RTs and erroneous button presses, suggesting a stimulus-specific feature matching process was adopted. Importantly, individual differences in the degree of sensitivity to these similarity measures correlated with conventional measures of attentional ability on the gradCPT as well as another CPT that is perceptually less demanding. In other words, individuals with greater sustained attention ability (assessed by two tasks) were more likely to be influenced by stimulus similarity on the gradCPT. These results suggest that sustained attention facilitates the construction and maintenance of an attentional template that is optimal for a given task.     

Neuropragmatics: Extralinguistic pragmatic ability is better preserved in left-hemisphere-damaged patients than in right-hemisphere-damaged patients

The aim of the present study is to compare the pragmatic ability of right- and left-hemisphere-damaged patients excluding the possible interference of linguistic deficits. To this aim, we study extralinguistic communication, that is communication performed only through gestures. The Cognitive Pragmatics Theory provides the theoretical framework: it predicts a gradient of difficulty in the comprehension of different pragmatic phenomena, that should be valid independently of the use of language or gestures as communicative means. An experiment involving 10 healthy individuals, 10 right- and 9 left-hemisphere-damaged patients, shows that pragmatic performance is better preserved in left-hemisphere-damaged (LHD) patients than in right-hemisphere-damaged (RHD) patients.     

Impaired ability to give a meaning to personally significant events in patients with schizophrenia

Schizophrenia is a severe mental illness affecting sense of identity. Autobiographical memory deficits observed in schizophrenia could contribute to this altered sense of identity. The ability to give a meaning to personally significant events (meaning making) is also critical for identity construction and self-coherence. Twenty-four patients with schizophrenia and 24 control participants were asked to recall five self-defining memories. We assessed meaning making in participants’ narratives (spontaneous meaning making) and afterwards asked them explicitly to give a meaning to their memories (cued meaning making). We found that both spontaneous and cued meaning making were impaired in patients with schizophrenia. This impairment was correlated with executive dysfunctions and level of negative symptoms. Our results suggest that patients’ difficulties in drawing lessons about past experiences could contribute to explain the lack of coherence observed in their life trajectories and their impaired social adjustment abilities. Implications for psychotherapy are also discussed.     

Visual recognition of biological motion is impaired in children with autism

Autistic children and typically developing control children were tested on two visual tasks, one involving grouping of small line elements into a global figure and the other involving perception of human activity portrayed in point-light animations. Performance of the two groups was equivalent on the figure task, but autistic children were significantly impaired on the biological motion task. This latter deficit may be related to the impaired social skills characteristic of autism, and we speculate that this deficit may implicate abnormalities in brain areas mediating perception of human movement.     

Susceptibility to induction of long-term depression is associated with impaired memory in aged Fischer 344 rats

The current study employed aged and young male Fischer 344 rats to examine the relationship between long-term depression (LTD), age, and memory. Memory performance was measured on two tasks that are sensitive to hippocampal function; inhibitory avoidance and spatial discrimination on the Morris water maze. The slope of the extracellular excitatory postsynaptic field potential was recorded from CA3-CA1 synapses in hippocampal slices. Low frequency stimulation (LFS) induced a modest LTD only in aged animals under standard recording conditions. The decrease in synaptic transmission examined only in aged animals correlated with memory scores on the spatial task and LTD was not observed in aged animals with the highest memory scores. LTD induction was facilitated by increasing the Ca(2+)/Mg(2+) ratio of the recording medium or employing a paired-pulse stimulation paradigm. Age differences disappeared when LFS was delivered under conditions of elevated Ca(2+)/Mg(2+) in the recording medium. Using multiple induction episodes under conditions which facilitate LTD-induction, no age-related difference was observed in the maximum level of LTD. The results indicate that the increased susceptibility to LTD induction is associated with impaired memory and results from a shift in the induction process. The possible relationship between LTD and memory function is discussed.     

Resting gamma power is linked to reading ability in adolescents

Infants who have more power within the gamma frequency range at rest develop better language and cognitive abilities over their first 3 years of life (Benasich et al., 2008). This positive trend may reflect the gradual increase in resting gamma power that peaks at about 4 years (Takano & Ogawa, 1998): infants further along the maturational curve may exhibit both increased resting gamma power and more advanced language and cognitive function. Similar to other neural characteristics such as synaptic density, resting gamma power subsequently decreases with further development into adulthood (Tierney, Strait, O'Connell & Kraus, 2013). If previously reported relationships between resting gamma power and behavioral performance reflect variance in maturation, at least in part, negative correlations between resting gamma and behavior may predominate in later developmental stages, during which resting gamma activity is decreasing. We tested this prediction by examining resting gamma activity and language‐dependent behavioral performance, reflected by a variety of reading‐related tests, in adolescents between the ages of 14 and 15 years. Consistent with our predictions, resting gamma power inversely related to every aspect of reading assessed (i.e. reading fluency, rapid naming, and basic reading proficiency). Our results suggest that resting gamma power acts as an index of maturational progress in adolescents.