The explanatory power of the Selfish Brain theory Selfish brain theory

1 explanatory power of selfish brain theory

1.1 investigative approach of selfish brain theory
1.2 energy procurement brain
1.3 healthy , diseased brain: energy supply through allocation or food intake
1.4 obesity - build-up in supply chain

the explanatory power of selfish brain theory
investigative approach of selfish brain theory

the brain performs many functions human organism. of cognitive nature or concern regulation of motor system. lesser investigated aspect of brain activity regulation of energy metabolism. selfish brain theory shed new light on function. states brain behaves selfishly controlling energy fluxes in such way allocates energy before needs of other organs satisfied. internal energy consumption of brain high. although mass constitutes 2% of entire body weight, consumes 20% of carbohydrates ingested on 24-hour period. corresponds 100 g of glucose per day, or half daily requirement human being. 30-year-old office worker body weight of 75 kg , height of 1.85 m consumes approx. 200 g glucose per day.

before scientific community assumed energy needs of brain, muscles , organs met in parallel. hypothalamus, area of upper brainstem, thought play central role in regulating 2 feedback loops within narrow limits.

the lipostatic theory established gordon c kennedy in 1953 describes fat deposition feedback system. hypothalamus receives signals circulating metabolic products or hormones how adipose tissue there in body prevailing metabolic status. using these signals hypothalamus can adapt absorption of nutrients body’s fat depots remain constant, i.e. lipostasis achieved.
the glucostatic theory developed in same year jean mayer describes blood glucose feedback system. according theory hypothalamus controls absorption of nutrients via receptors measure glucose level in blood. in way glucose concentration set adjusting intake of nutrients. interestingly enough, mayer included brain in calculations. although considered food intake served safeguard energy homoeostasis of central nervous system, did imply energy flux body brain passive process.

on basis of these theories number of international research groups still position origin of obesity in disorder in 1 of 2 above described feedback systems. however, there scenarios in weight regulation can not explained in way. example, upon inanition of body (e.g. during fasting) organs such heart, liver, spleen , kidneys dramatically lose weight (approx. 40%) , blood glucose concentration falls. during time, however, brain mass hardly changes (less 2% on average). further example illustrates inherent conflict between these 2 explanatory approaches: although large amounts of appetite suppressing hormone leptin released in obese individuals, still afflicted ravenous hunger once blood glucose falls.

the selfish brain theory links in seamlessly traditions of lipo- , glucostatic theories. new “selfish brain” theory assumes there feedback control system supraordinate blood glucose , fat feedback control systems.

a feedback system meant here in cerebral hemispheres, integrating organ entire central nervous system, control atp concentration (adenosine-triposphate - form of energy currency organism) of neurons (see 3). in way cerebral hemispheres ensure primacy of brain’s energy supply , therefore considered in selfish brain theory wings of central authority governs energy metabolism. whenever required cerebral hemispheres direct energy flux body brain maintain energy status. in contrast ideas of jean mayer, selfish brain theory assumes active energy on demand process. controlled cerebral atp sensors react sensitively changes in atp in neurons on entire brain.

the selfish brain theory combines theories of kennedy , mayer, considering blood glucose , fat feedback control systems complex. regulates energy flux environment body, i.e. intake of nutrients. regulated hypothalamic nucleus. here there sensors record changes in both blood glucose , fat depots, , activate biochemical processes maintain body weight.

for achieving goal of maintaining energy homeostasis in brain, cerebral hemispheres depend on subordinate feedback loops, since these loops send signals energy procurement control organ. if these signals not processed correctly, e.g. due impairments in amygdala or hippocampus, energy supply brain not endangered, anomalies such obesity can still result. origin of not found in blood glucose or fat feedback control systems, rather in regulating instances within cerebral hemispheres.

energy procurement brain

the brain can cover energy needs (particularly of cerebral hemispheres) either allocation or nutrient intake. corresponding signal subordinate regulatory system originates in cerebral hemispheres. phylogenetically recent part of brain characterized high plasticity , high capacity learn process. able adapt regulatory processes processing responses periphery, memorizing results of individual feedback loops , behaviors, , anticipating possible build-ups.

energy procurement brain complicated 3 factors. firstly, brain requests energy whenever needed. can store energy in restricted form. peters therefore refers energy on demand system. secondly, brain exclusively dependent on glucose atp-substrate. lactate , betahydroxybutyric acid can considered substrates, under conditions, e.g. considerable stress levels or malnutrition. thirdly, brain separated rest of body’s circulation blood-brain-barrier. blood glucose has brought there via special, insulin-independent transporter.

the healthy , diseased brain: energy supply through allocation or food intake

allocation represents way healthy brain secures energy supply when acutely needed. diverts blood glucose periphery , leads across blood-brain-barrier. important role here played stress system, neural pathways lead directly organs (heart, muscle, adipose tissue, liver, pancreas, etc.) , acts indirectly on these organs via bloodstream stress hormones adrenaline , cortisol. system ensures glucose transported brain, , uptake musculature , adipose tissue reduced. in order achieve that, release of insulin , effect on organs halted.

the acute supply of energy brain intake of nutrients presents problems organism. in event of emergency food intake activated if allocation insufficient, , must taken sign of disease. in case required energy can not requested body, , can taken directly environment. pathology due defects lying within control centers of brain such hippocampus, amygdala , hypothalamus. these may due mechanical (tumors, injuries), genetic defects (lacking brain-derived neurotrophic factor (bdnf) receptors or leptin receptors), faulty programming (post-traumatic stress disorder, conditioning of eating behavior, advertising sweets) or false signals may arise due influence of antidepressants, drugs, alcohol, pesticides, saccharin or viruses.

such disorders can have negative impact on number of behavioral types:

eating behavior (eating, drinking)
social behavior (e.g. dealing conflicts, sexuality)
behavior during food procurement (movement, orientation)

diseases can result. selfish brain” research group has concentrated above on obesity pathology.

the following applies irrespective of nature of energy provision: brain never gives on being selfish. peters therefore differentiates healthy diseased brain through ability compete energy requirements under adverse conditions there excessive demands body. contraposes selfish brain high fitness can tap bodies energy reserves in times of short food supply @ expense of body mass, , selfish brain low fitness , unable this, , instead takes in additional food , bears risk of developing obesity.

obesity - build-up in supply chain

the selfish brain theory can considered new way understand obesity. disorders in control centers of brain such hippocampus, amygdala , hypothalamus thought underlie this, outlined above. whatever type of disruption exists, entails energy procurement brain accomplished less allocation , more intake of nutrients though muscles have no additional energy requirement. if 1 imagines energy supply of human organism supply-chain passes outside world numerous options nutrient intake via body brain end user , control organ, obesity can considered being caused build-up in supply-chain. characterized excessive accumulation of energy in adipose tissue or blood. allocation failure expressed weakening of sympathetic nervous system (sns). result energy intended brain enters buffer storage areas, i.e. adipose tissue , musculature. small proportion reaches brain. in order cover huge energy needs brain commands individual consume more food. accumulation process escalates, , buffer storage areas continuously filled up. leads development of obesity. in many cases, @ time dependent on affected individual s personal disposition, obesity can overlain diabetes mellitus. in such situation adipose tissue , musculature can no longer accept energy, , energy accumulates in blood hyperglycemia results.