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- Title
Decision Making And Autonomic Function In Frontal Lobe Lesions.
- Authors
keshav Kumar, J.; Sathyaprabha, T. N.; Bhat, Dhananjaya I.
- Abstract
Every important aspect of life is preceded by decision making. Ranging from simple ones like when to wake up, what to eat to complex ones like which stock to invest in, whether to have a surgery, and whether to quit smoking, to name a few examples. Decision making involves, at its most basic level, the selection of one option from several alternatives. Properly executed decision making gives rise to some of the most elevated human abilities, such as ethics, politics, and financial reasoning (Naqvi, Shiv & Bechara, 2006). The role of prefrontal cortex in human decision-making has become a recent focus of study (Godefroy and Rousseaux, 1997; Rogers et al., 1999b; Satish et al., 1999; Bechara et al., 2000a; Sanfey et al., 2003). Anatomically, there is evidence that different frontal regions contribute uniquely to different decision sub processes The orbitofrontal cortex (OFC) appears to be relevant in situations involving incentive gain best-guess estimations, and the emotional experience associated with gains and losses. The dorsolateral prefrontal cortex (DLPFC) tends to be most involved in manipulating decision relevant information online, and in conscious deliberation during decisions. Other important frontal areas include the anterior cingulate (AC), involved in conflict processing and outcome relevant processing and the frontopolar cortex, which has been implicated in rule-based deciding, and selfgenerated information. Yet another neuroanotomically distinct area involved in decision making is ventromedial prefrontal cortex (VMF). Studies on VMF damage patients has shown that they are prone to impulsive decision making in real life and these same patients are impaired on laboratory decision-making tasks that require balancing rewards, punishments and risk (Bechara et al., 1994, 1997, 2000b; Rogers et al., 1999b; Sanfey et al., 2003). Moreover, damaged VMF disrupts social behavior profoundly. When there is a lesion due to a tumor/cyst in any of the areas mentioned the decision making will be impaired. The Somatic Marker Hypothesis proposes that 'somatic marker' biasing signals from the body are represented and regulated in the emotion circuitry of the brain, particularly the ventromedial prefrontal cortex (VMPFC), to help regulate decision-making in situations of complexity and uncertainty( Damasio, 1996; Bechara et al 2000). When making decisions, a crude biasing signals (a somatic marker) arising from the periphery or the central representation of the periphery indicates our emotional reaction to a response option. For every response option contemplated, a somatic state is generated, including sensations from the viscera, internal milieu, and the skeletal and smooth muscles (Damasio, 2004). These somatic markers serve as an indicator of the value of what is represented and also as a booster signal for continued working memory and attention (Damasio et al 1991; Damasio, 1996). In normal samples, Bechara et al. (1994, 1996) found a positive correlation between performance on the Iowa Gambling Task (IGT) and differential somatic markers for advantageous or disadvantageous decisions. Methodology: The present study looks into the psycho physiological changes associated with emotionally driven decision making- which is the performance of IGT in healthy control and frontal lobe lesion patients - using heart rate variability. The clinical sample consisted of 10 frontal lobe lesion patients diagnosed on the basis of CT & MRI by neurosurgeon. The patients were recruited from inpatient and outpatient department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore. A matched sample with the clinical group in gender and age was selected. Tools used- General Health Questionnaire (GHQ) (Goldberg and Hillier, 1972), Neurobehavioral Rating Scale (Levin, 1987): Iowa Gambling Test (IGT) (adapted from Bechara et al., 1994) and Autonomic Functions Test conducted in the Neurophysiology lab. Results: Both groups were comparable in terms of age gender education and marital status. The lesion location was on the frontal lobe. Both groups differ significantly on the General Health Questionnaire. The statistical analysis using chi square gives a p value of .001. On the Neurobehavioral Rating Scale there is significant difference between the patient group and control group. The chi square evaluation yields a p value of .000. On IGT, there was significant difference between the two groups on (C+D)-(A+B), p=.035 and no difference was found in the subsequent sections (P>.05). The basal heart rate variability (HRV) on supine posture, there was no significant difference between the groups (p>.05). The sitting heart rate variability (HRV) shown in the above table comparing the groups show there is no significant difference between both the groups (p>.05). The HRV assessed while doing IGT was found to be not significantly different between the two groups (p>.05). Implications: The current study gives an implication towards utility of IGT as a clinical instrument. The Neurophysiological changes are subtle and SMH is questionable in the face of other areas taking up the role. The possible compensatory mechanism contributed by OFC and VMPFC in DLPFC lesions and the use of this compensatory mechanism in retraining.
- Subjects
BENGALURU (India); FRONTAL lobe; DECISION making; FRONTAL lobe diseases; NATIONAL Institute of Mental Health (U.S.); WISCONSIN Card Sorting Test; HEART beat; PREFRONTAL cortex; GENERAL Health Questionnaire
- Publication
Journal of Cancer Research & Therapeutics, 2017, Vol 13, pS351
- ISSN
0973-1482
- Publication type
Article