The effect of Parkinson's disease on time estimation as a function of stimulus duration range and modality

The present research sought to investigate the role of the basal ganglia in timing of sub- and supra-second intervals via an examination of the ability of people with Parkinson's disease (PD) to make temporal judgments in two ranges, 100-500 ms, and 1-5 s. Eighteen non-demented medicated patients with PD were compared with 14 matched controls on a duration-bisection task in which participants were required to discriminate auditory and visual signal durations within each time range. Results showed that patients with PD exhibited more variable duration judgments across both signal modality and duration range than controls, although closer analyses confirmed a timing deficit in the longer duration range only. The findings presented here suggest the bisection procedure may be a useful tool in identifying timing impairments in PD and, more generally, reaffirm the hypothesised role of the basal ganglia in temporal perception at the level of the attentionally mediated internal clock as well as memory retrieval and/or decision-making processes.     

How fair treatment affects saliva cortisol release in stressed low and high type-A behavior individuals

The effects of fair treatment on saliva cortisol release of low and high Type-A behavior participants in high or low stress conditions are studied. Based on the Injustice Stress Theory (Vermunt & Steensma, 2001), predictions were made about fair treatment as a stress reducing factor. The results support the expected effect of fair treatment in that high type-A behavior participants in the low stress conditions had lower saliva cortisol levels after fair treatment while this effect was absent in the neutral condition, while low type-A behavior participants showed lower saliva cortisol release in the high stress conditions after fair treatment while this effect was absent in the neutral condition. Moreover, saliva cortisol scores are correlated positively with negative affect scores and negatively with positive affect scores. The discussion focuses on theoretical implications and suggestions for future research.     

Using TD learning to simulate working memory performance in a model of the prefrontal cortex and basal ganglia

Delayed-response tasks (DRTs) have been used to assess working memory (WM) processes in human and nonhuman animals. Experiments have shown that the basal ganglia (BG) and dorsolateral prefrontal cortex (DLPFC) subserve DRT performance. Here, we report the results of simulation studies of a systems-level model of DRT performance. The model was trained using the temporal difference (TD) algorithm and uses an actor-critic architecture. The matrisomes of the BG represent the actor and the striosomes represent the critic. Unlike existing models, we hypothesize that the BG subserve the selection of both motor- and cognitive-related information in these tasks. We also assume that the learning of both processes is based on reward presentation. A novel feature of the model is the incorporation of delay-active neurons in the matrisomes, in addition to DLPFC. Another novel feature of the model is the subdivision of the matrisomal neurons into segregated winner-take-all (WTA) networks consisting of delay- versus transiently-active units.Our simulation model proposes a new neural mechanism to account for the occurrence of perseverative responses in WM tasks in striatal-, as well as in prefrontal damaged subjects. Simulation results also show that the model both accounts for the phenomenon of time shifting of dopamine phasic signals and the effects of partial reinforcement and reward magnitude on WM performance at both behavioral and neural levels. Our simulation results also found that the TD algorithm can subserve learning in delayed-reversal tasks.     

Neural network processing of natural language: II. Towards a unified model of corticostriatal function in learning sentence comprehension and non-linguistic sequencing

A central issue in cognitive neuroscience today concerns how distributed neural networks in the brain that are used in language learning and processing can be involved in non-linguistic cognitive sequence learning. This issue is informed by a wealth of functional neurophysiology studies of sentence comprehension, along with a number of recent studies that examined the brain processes involved in learning non-linguistic sequences, or artificial grammar learning (AGL). The current research attempts to reconcile these data with several current neurophysiologically based models of sentence processing, through the specification of a neural network model whose architecture is constrained by the known cortico-striato-thalamo-cortical (CSTC) neuroanatomy of the human language system. The challenge is to develop simulation models that take into account constraints both from neuranatomical connectivity, and from functional imaging data, and that can actually learn and perform the same kind of language and artificial syntax tasks. In our proposed model, structural cues encoded in a recurrent cortical network in BA47 activate a CSTC circuit to modulate the flow of lexical semantic information from BA45 to an integrated representation of meaning at the sentence level in BA44/6. During language acquisition, corticostriatal plasticity is employed to allow closed class structure to drive thematic role assignment. From the AGL perspective, repetitive internal structure in the AGL strings is encoded in BA47, and activates the CSTC circuit to predict the next element in the sequence. Simulation results from Caplan's [Caplan, D., Baker, C., & Dehaut, F. (1985). Syntactic determinants of sentence comprehension in aphasia. Cognition, 21, 117-175] test of syntactic comprehension, and from Gomez and Schvaneveldts' [Gomez, R. L., & Schvaneveldt, R. W. (1994). What is learned from artificial grammars?. Transfer tests of simple association. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 396-410] artificial grammar learning experiments are presented. These results are discussed in the context of a brain architecture for learning grammatical structure for multiple natural languages, and non-linguistic sequences.     

Layer and regional effects of environmental enrichment on the pyramidal neuron morphology of the rat

The environmental enrichment (EE) paradigm is widely used to study experience-dependent brain plasticity. Several studies have investigated functional and anatomical EE effects. However, as EE effects are different according to cerebral region, cortical layer, dendritic field and morphological index considered, a univocal characterization of neuronal morphological changes following rearing in enriched environments is lacking.Aim of the present study was to characterize in the rat the effects of EE on the neuronal morphology of frontal and parietal cortical regions, the main target areas of the stimulation provided by the paradigm. Male Wistar rats were housed in an enriched environment for 3.5 months from the 21st postnatal day. For the morphological analysis, biotinylated dextran amine (BDA)-labeled pyramidal neurons were selected from frontal (M1–M2) and parietal (S1–S2) cortical layers III and V. Apical and basal dendritic branching and spines were analyzed using the Sholl method.Results showed that EE increased branching and spines in both layers of frontal cortex, but had a greater effect on apical arborization. In parietal cortex, EE significantly affected branching and spines in layer III but not layer V neurons, in which only a tendency to be influenced by the rearing conditions was observed in basal arborization.It is hypothesized that these multifaceted morphological EE effects are connected to the heavy involvement of a sensory-motor circuit engaged in the guidance of voluntary action and in motor learning activated by EE stimulation.     

Serum cortisol,testosterone, and testosterone-binding globulin responses to competitive fighting in human males

Levels of circulating cortisol, testosterone, and testosterone-binding globulin were measured in 15 male wrestlers in relation to wrestling bouts and their outcomes. Concentrations of cortisol and testosterone increased consistently during wrestling bouts, while levels of testosterone-binding globulin dropped. Winners of competive matches showed greater increases in both cortisol and testosterone than losers. These findings indicate that humans, like other social mammals, may undergo specific endocrine changes in response to victory or defeat.     

父母感知的家庭压力对儿童问题行为的影响：父母心理攻击和儿童应激下皮质醇反应的中介作用

儿童问题行为受到环境与个体因素的协同影响。研究以北京150名五、六年级儿童及其家长为被试,探究心理攻击和应激下皮质醇反应在父母感知的家庭压力与儿童问题行为间的中介作用。采用儿童版特里尔社会应激测试测量儿童应激下皮质醇反应,并由家长报告感知的家庭压力、对儿童的心理攻击及儿童的问题行为。结果发现：(1)父母感知的家庭压力可正向预测儿童问题行为;(2)心理攻击在父母感知的家庭压力与儿童问题行为间起中介作用;(3)心理攻击和儿童应激下皮质醇反应在父母感知的家庭压力与儿童问题行为之间起链式中介作用。研究揭示了父母感知压力对儿童问题行为影响的心理和生理机制,从父母和儿童角度为减少儿童问题行为提供了参考。     

The effects of gender,long-term need for recovery and trait inhibition-rumination on morning and evening saliva cortisol secretion

Abstract

The aim of this study was to investigate the long-term effects of need for recovery from work and trait rumination on saliva cortisol secretion. The sample consisted of 76 white-collar workers, 52 men and 24 women who had previously provided baseline data four years earlier and volunteered to participate in the present study. In the present study, saliva cortisol secretion was measured over seven consecutive days, on awakening, and at 10 p.m. No relationships were found between the independent variables and morning saliva cortisol levels. High trait rumination at baseline, however, was significantly related to higher evening cortisol levels for both women and men. Baseline need for recovery from work was strongly related to evening cortisol secretion for women, but in the opposite direction than expected. The present results add to the small but equivocal body of literature that has examined the long-term effects of work strain on cortisol secretion.     

Cortisol Response Following Exposure Treatment for PTSD in Rape Victims

This study examined changes in salivary cortisol levels pre- to posttreatment in adult female rape victims diagnosed with posttraumatic stress disorder (PTSD) randomly assigned to be treated with either prolonged exposure therapy or eye movement desensitization and reprocessing. Salivary cortisol was collected at baseline, Session 3, and Session 9. A significant decrease in salivary cortisol levels was observed in individuals classified as treatment responders in both treatment conditions. Findings suggest that successful exposure-based treatments for PTSD that result in trauma-related and depressive symptom reduction may impact the action of the hypothalamic–pituitary–adrenal axis as measured by changes in level of salivary cortisol from pre- to posttreatment.     

Decomposition of warning effects in Parkinson's disease

ABSTRACT

Neutral warning signals speed voluntary reactions by reducing temporal uncertainty and by triggering a brief burst of arousal. We attempted to isolate the phasic arousal mechanism in people with Parkinson's disease (PD) using a clock display to minimize temporal uncertainty. In this condition, the speeding of responses in a color-discrimination task by an accessory stimulus was the fully equivalent to the effect in age-matched control subjects. This indicates preserved phasic arousal in PD. Temporal preparation based on warning cues also appeared to be normal. By contrast, in a condition with high temporal uncertainty, the accessory stimulus (an air puff to the foot) impaired accuracy for the patients but not the neurologically normal subjects. The data are consistent with the view that PD disrupts internal but not external control of alertness.