Trevor W. Robbins

Bio: Trevor W. Robbins is an academic researcher from University of Cambridge. The author has contributed to research in topics: Prefrontal cortex & Impulsivity. The author has an hindex of 231, co-authored 1137 publications receiving 164437 citations. Previous affiliations of Trevor W. Robbins include Centre national de la recherche scientifique & Massachusetts Institute of Technology.

Disrupted `reflection' impulsivity in cannabis users but not current or former ecstasy users

Abstract: Evidence for serotonin involvement in impulsivity has generated interest in the measurement of impulsivity in regular ecstasy users, who are thought to display serotonergic dysfunction However, current findings are inconsistent Here, we used a recently developed Information Sampling Test to measure 'reflection' impulsivity in 46 current ecstasy users, 14 subjects who used ecstasy in the past, 15 current cannabis users and 19 drug-naive controls Despite elevated scores on the Impulsivity subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire, the current and previous ecstasy users did not differ significantly from the drug-naive controls on the Information Sampling Test In contrast, the cannabis users sampled significantly less information on the task, and tolerated a lower level of certainty in their decision-making, in comparison to the drug-naive controls The effect in cannabis users extends our earlier observations in amphetamine- and opiate-dependent individuals (Clark, et al, 2006, Biological Psychiatry 60: 515-522), and suggests that reduced reflection may be a common cognitive style across regular users of a variety of substances However, the lack of effects in the two ecstasy groups suggests that the relationship between serotonin function, ecstasy use and impulsivity is more complex

Selective depletion of cortical noradrenaline by anti-dopamine beta-hydroxylase-saporin impairs attentional function and enhances the effects of guanfacine in the rat.

Abstract: Rationale Previous data indicate that depletion of cortical noradrenaline (NA) impairs performance of an attentional five-choice serial reaction time task (5CSRT) under certain conditions. This study employed a novel immunotoxin, anti-dopamine-beta hydroylase (DβH)–saporin, to make relatively selective lesions of the noradrenergic projections to the prefrontal cortex (PFC) in rats trained to perform the 5CSRT.

Lateralisation of striatal function: evidence from 18F-dopa PET in Parkinson's disease

Abstract: Objectives: The aetiology of the cognitive changes seen in Parkinson's disease (PD) is multifactorial but it is likely that a significant contribution arises from the disruption of dopaminergic pathways. This study aimed to investigate the contribution of the dopaminergic system to performance on two executive tasks using 18F-6-fluorodopa positron emission tomography (18F-dopa PET) in PD subjects with early cognitive changes. Methods: 16 non-demented, non-depressed PD subjects were evaluated with the Tower of London (TOL) spatial planning task, a verbal working memory task (VWMT) and 18F-dopa PET, all known to be affected in early PD. Statistical parametric mapping (SPM) localised brain regions in which 18F-dopa uptake covaried with performance scores. Frontal cortical resting glucose metabolism was assessed with 18F-fluoro-2-deoxy-D-glucose (18F-FDG) PET. Results: SPM localised significant covariation between right caudate 18F-dopa uptake (Ki) and TOL scores and between left anterior putamen Ki and VWMT performance. No significant covariation was found between task scores and 18F-dopa Ki values in either limbic or cortical regions. Frontal cortical glucose metabolism was preserved in all cases. Conclusions: These findings support a causative role of striatal dopaminergic depletion in the early impairment of executive functions seen in PD. They suggest that spatial and verbal executive tasks require integrity of the right and left striatum, respectively, and imply that the pattern of cognitive changes manifest by a patient with PD may reflect differential dopamine loss in the two striatal complexes.

Disruptive effects of muscimol infused into the basal forebrain on conditional discrimination and visual attention: differential interactions with cholinergic mechanisms

Abstract: The behavioural effects of GABAergic manipulation of the basal forebrain were investigated using two behavioural tasks, which previous studies have shown to yield dissociable effects following quisqualate-induced lesions of the basal forebrain: a five-choice serial reaction time task, involving approaching the location of a brief visual stimulus that is associated with reward; and a conditional visual discrimination task, requiring retrieval of information about a discriminative stimulus that stays constant over time. Following acquisition of the tasks, chronic guide cannulae were stereotaxically implanted into the basal forebrain. Those animals trained on the conditional visual discrimination task showed a dose-dependent reduction in choice accuracy and a lengthening of latency to respond correctly to the visual stimulus following administration of the GABA-A agonist, muscimol (1, 2, 3 ng/µl/hem). While certain of these deficits, for example response latency, could be restored to control levels by co-administration of the GABA-A antagonist, bicuculline, none of the behavioural impairments could be significantly attenuated by systemic co-administration of the cholinesterase inhibitor, physostigmine (0.05, 0.1, 0.2 mg/kg, IP). Similarly, a dose dependent effect of muscimol (1, 1.5, 2 ng/µl/hem) on choice accuracy and correct response latency was observed on performance of the five-choice attentional task. However, in contrast to the conditional task, significant attenuation of the impairment in choice accuracy was obtained following administration of physostigmine (0.05 and 0.1 mg/kg). Attenuation of muscimol-induced deficits by administration of bicuculline was also observed. It is therefore evident that although manipulation of GABAergic activity in the region of the basal forebrain produces profound deficits in different tasks of cognitive function, only some of these may be due to modulation of the magnocellular cholinergic projection to the neocortex.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Control of goal-directed and stimulus-driven attention in the brain

Abstract: We review evidence for partially segregated networks of brain areas that carry out different attentional functions. One system, which includes parts of the intraparietal cortex and superior frontal cortex, is involved in preparing and applying goal-directed (top-down) selection for stimuli and responses. This system is also modulated by the detection of stimuli. The other system, which includes the temporoparietal cortex and inferior frontal cortex, and is largely lateralized to the right hemisphere, is not involved in top-down selection. Instead, this system is specialized for the detection of behaviourally relevant stimuli, particularly when they are salient or unexpected. This ventral frontoparietal network works as a 'circuit breaker' for the dorsal system, directing attention to salient events. Both attentional systems interact during normal vision, and both are disrupted in unilateral spatial neglect.

An integrative theory of prefrontal cortex function

Abstract: ▪ Abstract The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

Chapter 11 Working memory

Abstract: Publisher Summary This chapter focuses on the modern notion of short-term memory, called working memory. Working memory refers to the temporary maintenance of information that was just experienced or just retrieved from long-term memory but no longer exists in the external environment. These internal representations are short-lived, but can be maintained for longer periods of time through active rehearsal strategies, and can be subjected to various operations that manipulate the information in such a way that makes it useful for goal-directed behavior. Working memory is a system that is critically important in cognition and seems necessary in the course of performing many other cognitive functions, such as reasoning, language comprehension, planning, and spatial processing. This chapter demonstrates the functional importance of dopamine to working memory function in several ways. Elucidation of the cognitive and neural mechanisms underlying human working memory is an important focus of cognitive neuroscience and neurology for much of the past decade. One conclusion that arises from research is that working memory, a faculty that enables temporary storage and manipulation of information in the service of behavioral goals, can be viewed as neither a unitary, nor a dedicated system. Data from numerous neuropsychological and neurophysiological studies in animals and humans demonstrates that a network of brain regions, including the prefrontal cortex, is critical for the active maintenance of internal representations.