Dissociable contributions of the left and right posterior medial orbitofrontal cortex in motivational control of goal-directed behavior.

Several findings from both human neuroimaging and nonhuman primate studies suggest that the posterior medial orbitofrontal cortex (OFC) may be critical for the motivational control of goal-directed behavior. The present study was conducted to clarify the role of the left and right posterior medial OFC in that function by examining the effects of focal unilateral lesions to this region on the performance on an incentive working memory task. The study covered patients who had undergone surgery for an ACoA aneurysm and normal control subjects (C). The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) posterior part of the gyrus rectus, and without such a resection (GR-). Participants performed a 2-back working memory task under three motivational conditions (penalty, reward, and no-incentive). The C group performed worse in the penalty condition and better in the reward condition as compared to the no-incentive condition. Similar results were obtained for the GR- group. Performance of the LGR+ group did not depend on incentive manipulations, whereas the RGR+ group performed better in both the penalty and reward conditions than in the no-incentive condition. The results show that the posterior medial OFC is involved in the motivational modulation of working memory performance. Our findings also suggest that the left posterior medial OFC plays a crucial role in this function, whereas the right posterior medial OFC is particularly involved in the processing of the punishing aspect of salient events and it probably mediates in guiding behavior on the basis of negative outcomes of action.

[Preoperative anxiety assessed by questionnaires and patient declarations]. / Kwestionariuszowy i deklaratywny poziom leku chorych przed operacja.

BACKGROUND: The perioperative period can be anxiety-provoking for any patient scheduled for surgery. The anxiety can be divided into three categories: physiological, psychological and behavioural. For objective assessment, special questionnaires have been used, yet since they are too complicated for everyday use, simpler methods have been proposed. We have compared three measurements of anxiety to determine their equivalence in assessing anxiety before surgery: the State Trait Anxiety Inventory (STAI), the Visual Analogue Scale (VAS) and patient declaration in the form of an answer to a single question. METHODS: Thirty-eight ASA I and II adult patients, of both sexes, aged 18-60 years, and scheduled for elective abdominal or ENT surgery, were enrolled into the study. All patients were interviewed one day before the procedure and were asked to complete the STAI questionnaire, rate their fear on the VAS, and answer the question: "Are you afraid of anything?" The Kolmogorow-Smirnov test, t-Student test and r-Pearson correlation test were used for statistical analysis. RESULTS: Sixty six per cent of the questioned patients expressed a feeling of fear and their mean STAI-T (traid) score was 42.9 +/- 7.9, STAI-S (scale) 44.6 +/- 10.5. The VAS score was 3.7 +/- 2.6. Among those who did not declare a feeling of fear, the scores were: STAI-T: 36.9 +/- 8.2, STAI-S: 41.0 +/- 6.3, and VAS: 1.5 +/- 1.7. Females expressed a feeling of fear more often than males (p=0.03). There were no statistically significant differences related to age, the type of scheduled surgery or ASA score. The results obtained by all methods were closely correlated. CONCLUSION: We conclude that, since the results of anxiety measurement were comparable in all tests, a simple question or the VAS scale should be sufficient for proper assessment of preoperative anxiety.

Cognitive inhibition in patients with medial orbitofrontal damage.

Inhibition underlies cognitive processes such as overcoming habitual responses, suppressing of goal-irrelevant information, and switching of attention between stimuli or task rules. These processes are thought to depend on the frontal lobes. However, the precise role of the ventral frontal regions (orbitofrontal cortex) in these processes remains elusive. In the present study, our goal was to clarify the role of the orbitofrontal cortex in cognitive inhibition by examining the effects of focal lesions to the medial orbitofrontal cortex (posterior part of the gyrus rectus) on performance in tasks that required inhibitory control. Patients who had undergone surgery for an anterior communicating artery aneurysm and normal control subjects (C) participated in the study. The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). The Stroop Color-Word test, Trail Making B test, and the Category test were used as instruments for assessing response inhibition, switching between concrete stimuli, and switching between abstract task rules, respectively. In addition, the Digit Symbol test was used to examine sustained attention and processing speed. In the Stroop Color-Word test, the RGR+ group performed worse than all other groups. In the Trail Making B test, the RGR+ and LGR+ groups performed worse than both the GR- and C groups. In the Category test and Digit Symbol test, the groups did not differ significantly from each other. Our study indicates a specific contribution of the medial orbitofrontal cortex to response inhibition and stimulus-based switching of attention.

The role of the human ventromedial prefrontal cortex in memory for contextual information.

There is a growing body of evidence that the ventromedial prefrontal cortex (VMPFC) is implicated in the new learning of visual items. Little is known, however, as to the involvement of that portion of the prefrontal cortex in the learning of temporal and spatial relationship of those items. The aim of the present study, therefore, was to investigate the role of the VMPFC in memory for temporal and spatial order. Patients who had undergone surgery of the anterior communicating artery aneurysm, and normal control subjects (C), participated in the study. The patients were subdivided into three groups: with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). Subjects were presented with two memory tests: a temporal order (TO) test and a spatial order (SO) test. In the TO test, the LGR+ and RGR+ groups performed worse than the C group, while the GR- group did not differ significantly from the C group. In the SO test, the LGR+ and RGR+ groups did not differ significantly from the C and GR- groups. However, the trend appears to be the same for both tests, although only the TO test provides statistically significant group differences. Our results thus suggest that the VMPFC is involved in memory for contextual information. Together with previous findings, the data suggest that the learning of the relationship between items as well as the learning of those items are mediated by overlapping areas of the VMPFC.

Memory for object and object-location after lesions to the ventromedial prefrontal cortex in humans.

The aim of the present study was to investigate the effect of small unilateral lesions to the ventromedial portion of the prefrontal cortex on two memory functions: memory for objects and memory for object locations. Patients, who had undergone surgery of the anterior communicating artery aneurysm, and normal control subjects, participated in the study. The patients were subdivided into two groups: with and without unilateral resection of the gyrus rectus. Subjects were presented with two memory tests, that required remembering either simultaneously presented visual stimuli (object memory test; OMT) or locations of the stimuli (location memory test; LMT). In the OMT, patients with resection of the gyrus rectus were impaired in comparison to patients without resection and normal control subjects. In the LMT, the three groups did not differ from each other. Our results suggest that the ventromedial prefrontal cortex is specifically involved in memory for objects.