Frontal Lobe Functioning

Neurobehavioural and cognitive function is linked to childhood trauma in homeless adults

by Graham Pluck

Premorbid and current neuropsychological function in opiate abusers receiving treatment

by Graham Pluck

Better Without (Lateral) Frontal Cortex? Insight Problems Solved by Frontal Patients

by Alessio Toraldo

Reverberi C., Toraldo A., D’Agostini S., Skrap M. (2005). Brain 128, 2882-2890.

A recently proposed theory on frontal lobe functions claims that the prefrontal cortex, particularly its dorso-lateral... more A recently proposed theory on frontal lobe functions claims that the prefrontal cortex, particularly its dorso-lateral aspect, is crucial in defining a set of responses suitable for a particular task, and biasing these for selection. This activity is carried out for virtually any kind of non-routine tasks, without distinction of content. The aim of this study is to test the prediction of Frith's ‘sculpting the response space’ hypothesis by means of an ‘insight’ problem-solving task, namely the matchstick arithmetic task. Starting from Knoblich et al.'s interpretation for the failure of healthy controls to solve the matchstick problem, and Frith's theory on the role of dorsolateral frontal cortex, we derived the counterintuitive prediction that patients with focal damage to the lateral frontal cortex should perform better than a group of healthy participants on this rather difficult task. We administered the matchstick task to 35 patients (aged 26–65 years) with a single focal brain lesion as determined by a CT or an MRI scan, and to 23 healthy participants (aged 34–62 years). The findings seemed in line with theoretical predictions. While only 43% of healthy participants could solve the most difficult matchstick problems (‘type C’), 82% of lateral frontal patients did so (Fisher's exact test, P < 0.05). In conclusion, the combination of Frith's and Knoblich et al.'s theories was corroborated.

Compositionality of Rule Representations in Human Prefrontal Cortex

by Carlo Reverberi

Reverberi C, Görgen K, Haynes JD. (2011) Compositionality of Rule Representations in Human Prefrontal Cortex. Cerebral Cortex

Rules are widely used in everyday life to organize actions and thoughts in accordance with our internal goals. At the... more Rules are widely used in everyday life to organize actions and thoughts in accordance with our internal goals. At the simplest level, single rules can be used to link individual sensory stimuli to their appropriate responses. However, most tasks are more complex and require the concurrent application of multiple rules. Experiments on humans and monkeys have shown the involvement of a frontoparietal network in rule representation. Yet, a fundamental issue still needs to be clarified: Is the neural representation of multiple rules compositional, that is, built on the neural representation of their simple constituent rules? Subjects were asked to remember and apply either simple or compound rules. Multivariate decoding analyses were applied to functional magnetic resonance imaging data. Both ventrolateral frontal and lateral parietal cortex were involved in compound representation. Most importantly, we were able to decode the compound rules by training classifiers only on the simple rules they were composed of. This shows that the code used to store rule information in prefrontal cortex is compositional. Compositional coding in rule representation suggests that it might be possible to decode other complex action plans by learning the neural patterns of the known composing elements.

Cognitive vulnerability and frontal brain asymmetry: Common predictors of first prospective depressive episode

by Alexander Shackman

Nusslock, R., Shackman, A. J., Coan, J. A., Harmon-Jones, E., Alloy, L. B. & Abramson, L. Y. (2011). Relations between cognitive and neurophysiological vulnerability to depression. Journal of Abnormal Psychology, 120, 497-503.

The hopelessness theory of depression proposes that individuals with a depressogenic cognitive style are more likely... more The hopelessness theory of depression proposes that individuals with a depressogenic cognitive style are more likely to become hopeless and experience depression following negative life events. Although the neurophysiological underpinnings of cognitive style remain speculative, research indicates that decreased relative left frontal brain electrical activity holds promise as a trait-like marker of depression. This begs the question: Do measures of depressogenic cognitive style and resting frontal brain asymmetry index a common vulnerability? The present study provides preliminary support for this hypothesis. At baseline assessment, increased cognitive vulnerability to depression was associated with decreased relative left frontal brain activity at rest in individuals with no prior history of, or current, depression. Following baseline assessment, participants were followed prospectively an average of 3 years with structured diagnostic interviews at 4-month intervals. Both cognitive vulnerability and asymmetric frontal cortical activity prospectively predicted onset of first depressive episode in separate univariate analyses. Furthermore, multivariate analyses indicated that cognitive vulnerability and frontal asymmetry represented shared, rather than independent, predictors of first depression onset.

Awareness of everyday executive difficulties precede overt executive dysfunction in schizotypal subjects

by Keith Laws

Much evidence indicates that schizophrenic patients exhibit deficits on tests of executive functioning. It is... more Much evidence indicates that schizophrenic patients exhibit deficits on tests of executive functioning. It is therefore hypothesized that individuals with high schizotypal personality traits that may have a predisposition to schizophrenia, are also likely to exhibit impairments in neuropsychological tests of executive function. The sample consisted of 65 healthy controls that were divided into high and low scorers on the Schizotypal Personality Questionnaire (SPQ-B: Raine et al., 1995). Participants completed a battery of executive tasks (category and letter fluency, the Hayling test, Zoo map); however, a MANOVA revealed no significant differences
between high and low SPQ scorers. Nevertheless, high SPQ scorers scored significantly higher on the Dysexecutive Questionnaire (DEX) self-rating scale of everyday executive problems; and these self-ratings correlated significantly with the disorganisation and cognitive–perceptual features of the SPQ-B, but not with the interpersonal features. This suggests that perceived executive dysfunction is pre-morbidly present and may become evident in test performance only with the onset of schizophrenia itself.