Dr Natalia Lawrence
Senior Lecturer (in Translational Medicine)

Key publications | Publications by category | Publications by year

Key publications



Lawrence NS, Verbruggen F, Morrison S, Adams RC, Chambers CD (2015). Stopping to food can reduce intake. Effects of stimulus-specificity and individual differences in dietary restraint. Appetite, 85, 91-103.

Abstract:
Stopping to food can reduce intake. Effects of stimulus-specificity and individual differences in dietary restraint.

Overeating in our food-rich environment is a key contributor to obesity. Computerised response-inhibition training could improve self-control in individuals who overeat. Evidence suggests that training people to inhibit motor responses to specific food pictures can reduce the subsequent choice and consumption of those foods. Here we undertook three experiments using the stop-signal task to examine the effects of food and non-food related stop-training on immediate snack food consumption. The experiments examined whether training effects were stimulus-specific, whether they were influenced by the comparator (control) group, and whether they were moderated by individual differences in dietary restraint. Experiment 1 revealed lower intake of one food following stop- vs. double- (two key-presses) response training to food pictures. Experiment 2 offered two foods, one of which was not associated with stopping, to enable within- and between-subjects comparisons of intake. A second control condition required participants to ignore signals and respond with one key-press to all pictures. There was no overall effect of training on intake in Experiment 2, but there was a marginally significant moderation by dietary restraint: Restrained eaters ate significantly less signal-food following stop- relative to double-response training. Experiment 3 revealed that stop- vs. double-response training to non-food pictures had no effect on food intake. Taken together with previous findings, these results suggest some stimulus-specific effects of stop-training on food intake that may be moderated by individual differences in dietary restraint.
 Abstract.  Author URL Full text
Lawrence NS, O‘Sullivan J, Parslow D, Javaid M, Adams RC, Chambers CD, Kos K, Verbruggen F (2015). Training response inhibition to food is associated with weight loss and reduced energy intake. Appetite, 95, 17-28.

Abstract:
Training response inhibition to food is associated with weight loss and reduced energy intake

The majority of adults in the UK and US are overweight or obese due to multiple factors including excess energy intake. Training people to inhibit simple motor responses (key presses) to high-energy density food pictures reduces intake in laboratory studies. We examined whether online response inhibition training reduced real-world food consumption and weight in a community sample of adults who were predominantly overweight or obese (N = 83). Participants were allocated in a randomised, double-blind design to receive four 10-min sessions of either active or control go/no-go training in which either high-energy density snack foods (active) or non-food stimuli (control) were associated with no-go signals. Participants' weight, energy intake (calculated from 24-h food diaries), daily snacking frequency and subjective food evaluations were measured for one week pre- and post-intervention. Participants also provided self-reported weight and monthly snacking frequency at pre-intervention screening, and one month and six months after completing the study. Participants in the active relative to control condition showed significant weight loss, reductions in daily energy intake and a reduction in rated liking of high-energy density (no-go) foods from the pre-to post-intervention week. There were no changes in self-reported daily snacking frequency. At longer-term follow-up, the active group showed significant reductions in self-reported weight at six months, whilst both groups reported significantly less snacking at one- and six-months. Excellent rates of adherence (97%) and positive feedback about the training suggest that this intervention is acceptable and has the potential to improve public health by reducing energy intake and overweight.
 Abstract. Full text
Dymond S, Lawrence NS, Dunkley BT, Yuen KS, Hinton EC, Dixon MR, Cox WM, Hoon ae, Munnelly A, Muthukumaraswamy SD, et al (2014). Almost winning: induced MEG theta power in insula and orbitofrontal cortex increases during gambling near-misses and is associated with BOLD signal and gambling severity. Neuroimage, 91, 210-219.

Abstract:
Almost winning: induced MEG theta power in insula and orbitofrontal cortex increases during gambling near-misses and is associated with BOLD signal and gambling severity.

In slot machine gambling, the "near-miss effect" (when a losing display physically resembles an actual win display) has been implicated in pathological gambling (PG). Functional magnetic resonance imaging (fMRI) with PG and non-PG participants shows that near-misses recruit reward-related circuitry, but little is known about the temporal dynamics and oscillatory changes underlying near-misses. The present multi-modal imaging study investigated the near-miss effect by combining the spatial resolution of blood oxygen-level dependent (BOLD)-fMRI with the spatial and temporal resolution of magnetoencephalography (MEG) during a slot machine task in PG and non-PG groups. Given previous findings on outcome (win and near-miss) processing, functional overlap was hypothesized between induced changes in temporal oscillations and BOLD response to wins and near-misses in PG. We first validated our task in a sample of varying gambling severity using BOLD-fMRI and then compared PG and non-PG participants using MEG to investigate changes in induced oscillatory power associated with win and near-miss, relative to loss, outcomes. Across both modalities, near-misses recruited similar brain regions to wins, including right inferior frontal gyrus and insula. Using MEG, increased theta-band (4-7Hz) oscillations to near-misses were observed in the insula and right orbitofrontal cortex (OFC). Furthermore, this theta-band activity was positively associated with gambling severity. These findings demonstrate that the near-miss effect in insula and OFC is associated with induced theta oscillations. The significance of these findings for theories of PG and the development of potential biomarkers and therapeutic targets is discussed.
 Abstract.  Author URL
Caseras X, Lawrence NS, Murphy K, Wise RG, Phillips ML (2013). Ventral striatum activity in response to reward: differences between bipolar I and II disorders. Am J Psychiatry, 170(5), 533-541.

Abstract:
Ventral striatum activity in response to reward: differences between bipolar I and II disorders.

OBJECTIVE: Little is known about the neurobiology of bipolar II disorder. While bipolar I disorder is associated with abnormally elevated activity in response to reward in the ventral striatum, a key component of reward circuitry, no studies have compared reward circuitry function in bipolar I and bipolar II disorders. Furthermore, associations among reward circuitry activity, reward sensitivity, and striatal volume remain underexplored in bipolar and healthy individuals. The authors examined reward activity in the ventral striatum in participants with bipolar I and II disorders and healthy individuals, the relationships between ventral striatal activity and reward sensitivity across all participants, and between-group differences in striatal gray matter volume and relationships with ventral striatal activity across all participants. METHOD: Twenty healthy comparison subjects and 32 euthymic bipolar I (N=17) and bipolar II (N=15) patients underwent a neuroimaging reward paradigm during functional MRI scanning, structural scanning, and completed psychometric and clinical assessments. RESULTS: Region-of-interest analyses revealed significant ventral striatal activity in all participants during reward anticipation that was significantly greater in bipolar II patients compared with the other groups. Ventral striatal activity during reward anticipation correlated positively with reward sensitivity and fun seeking across all participants. Bipolar II patients had significantly greater left putamen volume than bipolar I patients, and left putamen volume correlated positively with left ventral striatal activity to reward anticipation in all participants. CONCLUSIONS: Abnormally elevated ventral striatal activity during reward anticipation may be a potential biomarker of bipolar II disorder. These findings highlight the importance of adopting a dimensional approach in the study of neural mechanisms supporting key pathophysiological processes that may cut across psychiatric disorders.
 Abstract.  Author URL Full text
Lawrence NS, Hinton EC, Parkinson JA, Lawrence AD (2012). Nucleus accumbens response to food cues predicts subsequent snack consumption in women and increased body mass index in those with reduced self-control. Neuroimage, 63(1), 415-422.

Abstract:
Nucleus accumbens response to food cues predicts subsequent snack consumption in women and increased body mass index in those with reduced self-control.

Individuals have difficulty controlling their food consumption, which is due in part to the ubiquity of tempting food cues in the environment. Individual differences in the propensity to attribute incentive (motivational) salience to and act on these cues may explain why some individuals eat more than others. Using fMRI in healthy women, we found that food cue related activity in the nucleus accumbens, a key brain region for food motivation and reward, was related to subsequent snack food consumption. However, both nucleus accumbens activation and snack food consumption were unrelated to self-reported hunger, or explicit wanting and liking for the snack. In contrast, food cue reactivity in the ventromedial prefrontal cortex was associated with subjective hunger/appetite, but not with consumption. Whilst the food cue reactivity in the nucleus accumbens that predicted snack consumption was not directly related to body mass index (BMI), it was associated with increased BMI in individuals reporting low self-control. Our findings reveal a neural substrate underpinning automatic environmental influences on consumption in humans and demonstrate how self-control interacts with this response to predict BMI. Our data provide support for theoretical models that advocate a 'dual hit' of increased incentive salience attribution to food cues and poor self-control in determining vulnerability to overeating and overweight.
 Abstract.  Author URL
Jollant F, Lawrence NS, Olie E, O‘Daly O, Malafosse A, Courtet P, Phillips ML (2010). Decreased activation of lateral orbitofrontal cortex during risky choices under uncertainty is associated with disadvantageous decision-making and suicidal behavior. Neuroimage, 51(3), 1275-1281.

Abstract:
Decreased activation of lateral orbitofrontal cortex during risky choices under uncertainty is associated with disadvantageous decision-making and suicidal behavior.

Decision-making impairment has been linked to orbitofrontal cortex lesions and to different disorders including substance abuse, aggression and suicidal behavior. Understanding the neurocognitive mechanisms of these impairments could facilitate the development of effective treatments. In the current study, we aimed to explore the neural and cognitive basis of poor decision-making ability associated with the vulnerability to suicidal behavior, a public health issue in most western countries. Twenty-five not currently depressed male patients, 13 of whom had a history of suicidal acts (suicide attempters) and 12 of whom had none (affective controls), performed an adapted version of the Iowa Gambling Task during functional Magnetic Resonance Imaging. Task-related functional Regions-of-Interest were independently defined in 15 male healthy controls performing the same task (Lawrence et al., 2009). In comparison to affective controls, suicide attempters showed 1) poorer performance on the gambling task 2) decreased activation during risky relative to safe choices in left lateral orbitofrontal and occipital cortices 3) no difference for the contrast between wins and losses. Altered processing of risk under conditions of uncertainty, associated with left lateral orbitofrontal cortex dysfunction, could explain the decision-making deficits observed in suicide attempters. These impaired cognitive and neural processes may represent future predictive markers and therapeutic targets in a field where identification of those at risk is poor and specific treatments are lacking. These results also add to our growing understanding of the role of the orbitofrontal cortex in decision-making and psychopathology.
 Abstract.  Author URL

Back | Top of page | Edit Profile | Refresh page