certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure , function , manufacture , and use of the devices and methods disclosed herein . one or more examples of these embodiments are illustrated in the accompanying drawings . those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non - limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims . the features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments . such modifications and variations are intended to be included within the scope of the present invention . fig1 is a schematic view of a human stomach 100 . esophagus 102 , which meets stomach 100 at antrum 104 , serves as an inlet for ingested food content . at the uppermost region of stomach 100 resides fundus 106 . fundus 106 is the region of the stomach where most of the ghrelin hormone producing cells reside . stomach 100 is generally defined by greater curvature 108 and lesser curvature 110 , and is bound by anterior wall 112 . at the lowermost region of the stomach reside angular notch 114 , pylorus 116 and duodenum 118 . together , angular notch 114 , pylorus 116 and duodenum 118 serve as an outlet for the contents of the stomach to pass into the intestines ( not shown ); the digestive process being aided by gall bladder 122 . ghrelin expression zones 120 are defined within stomach 100 in areas generally defined by fundus 106 and duodenum 118 . fig2 is a schematic view of human stomach 100 following a magenstrasse and mill ( m & amp ; m ) surgical procedure . the m & amp ; m surgical procedure is generally accomplished by creating a vertical transection , division or separation 200 of the gastric cavity of stomach 100 generally along lesser curvature 110 from antrum 104 to a point roughly 4 - 6 cm from pylorus 116 . a transorally delivered bougie ( not shown ) is often placed into the pylorus . the bougie is pressed against lesser curvature 110 with a stapling device ( not shown ) and helps determine the location of separation 200 . the size of the bougie chosen by the surgeon aids in determining the size of the lumen of first stomach chamber 202 . the bougie also helps the surgeon create a lumen in chamber 202 that is uniform in diameter . as may be appreciated , the performance of an m & amp ; m surgical procedure serves the function of partitioning stomach into a first chamber 202 and a second chamber 204 . first chamber 202 contains and permits flow therethrough of food content and dietary lipids ( not shown ). second chamber 204 contains the bulk of the ghrelin hormone producing cells present in stomach 100 . it should be appreciated that similar procedures for separating the stomach , whether physically or virtually are contemplated and may be performed in place of or in concert with the m & amp ; m surgical procedure disclosed herein . details of such a procedure are disclosed herein with respect to fig1 a - 10e . fig3 is schematic partially transparent view of human stomach 100 following a magenstrasse and mill ( m & amp ; m ) surgical procedure and implantation of a controlled evacuation device 300 . in this particular embodiment , controlled evacuation device 300 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 302 and an outlet 304 . in this particular embodiment , controlled evacuation device 300 is illustrated as a conical or funnel shaped device where inlet 302 substantially surrounds the space between vertical separation 200 and the bottom portion of anterior wall 112 to substantially create a seal between first chamber 202 and second chamber 204 , although it should be understood that various other shapes may be employed by one having ordinary skill in the art without departing from the scope of the present invention . accordingly , in this embodiment , controlled evacuation device 300 may prevent contact within the stomach of the non - activated ghrelin cells and dietary lipids of first chamber 202 in order to induce or maintain a fat burning metabolic state , thereby causing weight loss in an obese patient . as will be discussed in greater detail later herein , controlled evacuation device 300 may comprise a valve which is functional to provide controlled one - way fluid flow therethrough , and to prevent retrograde flow of food content and dietary lipids through controlled evacuation device 300 by way of peristaltic stomach motions . as may be appreciated , controlled evacuation device 300 may have alternate forms and placements within stomach 100 without departing from the scope of the present invention . fig4 is a schematic view of human stomach 100 following a magenstrasse and mill ( m & amp ; m ) surgical procedure and creation of a passive biological one - way valve 400 . in this particular embodiment , passive biological one - way valve 400 is functional to regulate the contact between dietary lipids of first chamber 202 and the non - activated ghrelin cells contained within second chamber 204 in order to achieve a desired effect . passive biological one - way valve 400 may be formed , for example , via tissue folding or tissue removal . cross - sectional views of a passive biological one - way valve taken along section line a - a will be discussed in greater detail later herein with respect to fig6 a and 6b . further , passive biological one - way valve 400 may also include an implantable prosthetic device such as a one - way osmotic membrane . as may be appreciated , passive biological one - way valve 400 may have alternate forms and placements within stomach 100 without departing from the scope of the present invention . fig5 a and 5b are schematic partially transparent views of human stomach 100 following the implantation of a gastric sleeve 500 . in these particular embodiments , gastric sleeve 500 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 502 and an outlet 504 . in these particular embodiments , gastric sleeve 500 is secured at its inlet 502 to esophagus 102 near antrum 104 via anchoring stent 506 . in fig5 a , outlet 504 extends to a point beyond pylorus 116 , but terminates prior to ghrelin expression zone 120 of duodenum 118 . in fig5 b , outlet 504 extends to a point beyond ghrelin expression zone 120 of duodenum 118 . in this manner , the length of gastric sleeve 500 may be tailored to the specific needs of the patient , as determined by their physician without departing from the scope of the present invention . accordingly , food content and dietary lipids are effectively separated from the ghrelin hormone producing cells present in fundus 106 and / or duodenum 118 , thereby preventing activation of ghrelin by the enzyme ghrelin - octanoyl acyl - transferase ( goat ). this isolation may aid in reducing or eliminating hunger sensations , as well as inducing or maintaining a fat burning metabolic state , thereby causing weight loss in an obese patient . as may be appreciated , gastric sleeve 500 may have alternate forms and placements within stomach 100 with the primary function remaining as separating food content and dietary lipids from the ghrelin hormone producing cells present in fundus 106 . further , it should be understood that known gastric sleeves and sleeve gastrectomy methods may be employed , without changing or altering the scope of the present invention . fig6 a is a cross - sectional view of a passive biological one - way valve 400 in an open position , as taken along section line a - a of fig4 . as disclosed previously herein , passive biological one - way valve 400 may be formed , for example , via tissue plication or tissue removal . accordingly , in this particular embodiment , passive biological one - way valve 400 includes a first tissue fold 602 and a second tissue fold 604 which cooperate to form a valve which separates second chamber 204 of stomach 100 from the formed outlet chamber 606 . in the open position of fig6 a , the stomach fluids contained within second chamber 204 are free to be evacuated into outlet chamber 606 , and subsequently through outlet passage 608 . as may be appreciated , passive biological one - way valve 400 may have alternate forms ( e . g ., one or more plications may be created to obtain the desired effect ) and placements within stomach 100 with the primary function remaining as controlling evacuation of stomach fluids from second chamber 204 . fig6 b is a cross - sectional view of a passive biological one - way valve 400 in a closed position , as taken along section line a - a of fig4 . as disclosed previously herein , passive biological one - way valve 400 may be formed , for example , via tissue plication or tissue removal . accordingly , in this particular embodiment , passive biological one - way valve 400 includes a first tissue fold 602 and a second tissue fold 604 which cooperate to form a valve which separates second chamber 204 of stomach 100 from the formed outlet chamber 606 . in the closed position of fig6 b , the stomach fluids contained within second chamber 204 are collected before being evacuated into outlet chamber 606 , and subsequently through outlet passage 608 . in this embodiment , dietary lipids are prevented from contacting the ghrelin producing cells in second chamber 204 . as may be appreciated , passive biological one - way valve 400 may have alternate forms and placements within stomach 100 with the primary function remaining as controlling evacuation of stomach fluids from second chamber 204 . fig7 is a schematic partially transparent view of a controlled evacuation device 700 comprising a duck bill valve . in this particular embodiment , controlled evacuation device 700 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 702 and an outlet 704 . within the internal bore resides a duck bill valve formed by a first elongated member 706 and a second elongated member 708 . first elongated member 706 and a second elongated member 708 are resiliently biased to a normally closed configuration as seen in fig7 , but allow for passage of materials therethrough . in one embodiment , the material passing therethrough is the stomach fluids contained within second chamber 204 as described previously herein with respect to fig3 . fig8 is a schematic partially transparent view of a controlled evacuation device 800 comprising an internal ball valve . in this particular embodiment , controlled evacuation device 800 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 802 and an outlet 804 . within the internal bore resides a ball valve formed by a first elongated member 806 and a second elongated member 808 which interact with a ball 810 . ball 810 may be resiliently biased to a normally closed configuration as seen in fig8 , but allow for passage of materials therethrough . in one embodiment , the material passing therethrough is the stomach fluids contained within second chamber 204 as described previously herein with respect to fig3 . as may be appreciated , ball 810 may be constructed of a suitable material such as polyetheretherketone ( peek ) or silicone and have a suitable size and shape for use within a human stomach . fig9 is a schematic partially transparent view of a controlled evacuation device 900 comprising an osmotic membrane . in this particular embodiment , controlled evacuation device 900 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 902 and an outlet 904 . within the internal bore resides an osmotic membrane 906 . osmotic membrane 906 allows for one - way fluid passage therethrough . in one embodiment , the fluid passing therethrough is the stomach fluids contained within second chamber 204 as described previously herein with respect to fig3 . fig1 a - 10e illustrate a schematic view of human stomach 100 undergoing the basic steps of a modified magenstrasse and mill ( m & amp ; m ) type surgical procedure . in fig1 a , a first division or separation 1000 is created in stomach 100 . in fig1 b , a second division or separation 1002 is created in stomach 100 . in fig1 c , first division or separation 1000 is separated to create two distinct stomach chambers ; first stomach chamber 202 and second stomach chamber 204 . in fig1 d , second division or separation 1002 is also separated to further define first stomach chamber 202 and second stomach chamber 204 . in fig1 e , second stomach chamber 204 is secured to inert structural tissue 1004 in the abdominal cavity of the patient by sutures 1006 or the like . in this manner , narrow passage 1008 between first division or separation 1000 and second division or separation 1002 serves as the only fluid communication passage between first stomach chamber 202 and second stomach chamber 204 , thereby controlling the fluid communication between the dietary lipids contained within first stomach chamber 202 and the ghrelin hormone producing cells present second stomach chamber 204 . this in turn prevents activation of the non - activated ghrelin cells which will induce or maintain a fat burning metabolic state , thereby causing weight loss in an obese patient . as may be appreciated , passage 1008 may further include a valve means ( not shown ) which may , for example , comprise either an implanted mechanical device or a surgically created biological one - way valve which have been detailed previously herein in other embodiments . fig1 is a schematic partially transparent view of human stomach 100 following the implantation of a duodenal sleeve 1100 . in this particular embodiment , duodenal sleeve 1100 is anchored at its inlet 1108 by anchoring stent 1102 within duodenum 118 . in these particular embodiments , duodenal sleeve 1100 is an implanted device having a tubular configuration with an internal bore passing therethrough , thereby defining an inlet 1108 and an outlet 1110 . in fig1 , outlet 1110 of duodenal sleeve 1100 extends to a point beyond ghrelin expression zone 120 of duodenum 118 ( see fig1 ). in this manner , the length of duodenal sleeve 1100 may be tailored to the specific needs of the patient , as determined by their physician without departing from the scope of the present invention . accordingly , food content and dietary lipids 1104 pass through duodenal sleeve 1100 in a direction indicated by flow arrow 1106 and are effectively separated from the ghrelin hormone producing cells present in duodenum 118 , thereby preventing activation of ghrelin by the enzyme ghrelin - octanoyl acyl - transferase ( goat ). this isolation may aid in reducing or eliminating hunger sensations , as well as inducing or maintaining a fat burning metabolic state , thereby causing weight loss in an obese patient . as may be appreciated , duodenal sleeve 1100 may have alternate forms and placements within duodenum 118 with the primary function remaining as separating food content and dietary lipids from the ghrelin hormone producing cells present in duodenum 118 . further , it should be understood that known duodenal sleeves and sleeve gastrectomy methods may be employed , without changing or altering the scope of the present invention . fig1 is schematic partially transparent view of human stomach 100 following a magenstrasse and mill ( m & amp ; m ) surgical procedure and implantation of a controlled evacuation device 1200 and a duodenal sleeve 1100 . controlled evacuation device 1200 includes an inlet 1202 and an outlet 1204 and comprises a valve which is functional to provide controlled one - way fluid flow therethrough , and to prevent retrograde flow of food content and dietary lipids through controlled evacuation device 1200 by way of peristaltic stomach motions . accordingly , in this embodiment , controlled evacuation device 1200 may prevent contact within the stomach of the non - activated ghrelin cells and dietary lipids of first chamber 202 in order to induce or maintain a fat burning metabolic state , thereby causing weight loss in an obese patient . as may be appreciated , controlled evacuation device 1200 may have alternate forms ( e . g ., a passive biological one - way valve as in fig4 above ) and placements within stomach 100 without departing from the scope of the present invention . the m & amp ; m procedure of fig1 is equivalent to that of the m & amp ; m procedure detailed previously herein with respect to fig2 . the implantation of duodenal sleeve 1100 is equivalent to that of the procedure detailed previously herein with respect to fig1 . fig1 is schematic partially transparent view of human stomach 100 following a sleeve gastrectomy procedure and implantation of a duodenal sleeve 1100 . in fig1 , a division or separation 1302 is created in stomach 100 in order to create two distinct stomach portions ; first portion 1304 and second portion 1306 . in this embodiment , second portion 1306 comprising fundus 106 is excised leaving stomach 100 having portion 1304 as its new effective volume . in this manner , the ghrelin producing portions of fundus 106 are removed from the body and are therefore incapable of being contacted by the dietary lipids and food content within stomach 100 . non - limiting disclosures of the sleeve gastrectomy procedure can be found an example of this is disclosed in us2005 / 0131386a1 , jun . 16 , 2005 “ method and device for minimally invasive implantation of biomaterial ”, which is hereby incorporated by reference in their entirety . the implantation of duodenal sleeve 1100 is equivalent to that of the procedure detailed previously herein with respect to fig1 . fig1 a - c are schematic views of hydrophilic foam barrier 1400 . in fig1 a , hydrophilic foam barrier 1400 is a unitary implantable device , whereas in fig1 b and 14c barrier 1400 is a segmented ingestible device . in these figures , barrier 1400 is constructed from multiple smaller sections 1402 . each section 1402 would be small enough to pass in the expanded state shown . one embodiment of a construction method would be to hold the sections together with bioabsorbable suture 1404 . that way , barrier 1400 could be implanted in one easily maneuverable piece , but would break up into passable sections in the unlikely event that it becomes dislodged from the gastric fixturing means ( discussed below ). the idea described in this document uses a moist barrier to repel lipids from areas of the stomach or small bowel that contain goat . in one embodiment , barrier 1400 is a highly hydrophilic and is constructed of a porous material . fig1 a - c are schematic partially transparent views of human stomach 100 following a transoral introduction and laparoscopic fixation of hydrophilic foam barrier 1400 . fig1 a illustrates a first step in the process wherein barrier 1400 is rolled , compressed and inserted into stomach 100 orally . fig1 b illustrates a second step in the process wherein barrier 1400 is unrolled and positioned in fundus 106 using a flexible endoscope with standard tools ( not shown ). fig1 c illustrates a third step in the process wherein using a laparoscopic device 1500 , the anterior and posterior layers of stomach 100 are forced into contact with barrier 1400 , not compressing the barrier fully . fasteners 1502 are inserted through the anterior stomach layer , barrier 1400 and the posterior stomach layer in order to hold barrier 1400 in place . fig1 d - e are a schematic view and cross sectional view respectively of human stomach 100 following a transoral introduction and laparoscopic fixation of an hydrophilic foam barrier 1400 and details thereof . as shown and described previously herein with respect to fig1 a - c , fig1 d illustrates barrier 1400 fastened between the anterior stomach layer and the posterior stomach layer via fasteners 1502 and further includes a section line a - a . fig1 e as taken along section line a - a illustrates barrier 1400 fastened between the anterior stomach layer and the posterior stomach layer via fasteners 1502 in order to be better understood . fig1 f - g is are schematic partially transparent views of human stomach 100 following a transoral introduction and laparoscopic fixation of a barrier illustrating a water path and a lipid path respectively within stomach 100 . in fig1 f a portion of water 1504 introduced by ingestion is retained in barrier 1400 . also , secretions from fundus area 106 of stomach 100 can pass through barrier 1400 for drainage , because they are water based . however , as seen in fig1 g , ingested lipids 1506 are repelled by barrier 1400 due to the fact that the porous material is engorged with water 1504 , and lipids 1506 are hydrophobic . therefore , it is ensured that lipids 1506 do not contact the goat containing tissue within fundus 106 . this isolation may aid in reducing or eliminating hunger sensations , as well as inducing or maintaining a fat burning metabolic state , thereby causing weight loss in an obese patient . one skilled in the art will appreciate further features and advantages of the invention based on the above - described embodiments . accordingly , the invention is not to be limited by what has been particularly shown and described , except as indicated by the appended claims . all publications and references cited herein are expressly incorporated herein by reference in their entirety .
methods and devices regulate the activation of ghrelin hormones within a stomach in order to treat weight disorders , to promote learning and memory functions , to treat stress - induced depression , and to control sleep duration . in one embodiment , a method for regulating activation of ghrelin hormones within a stomach comprises a means for isolating non - activated ghrelin hormones from food content and dietary lipids within the stomach . these means for isolating may take any number of forms and may comprise one or more of a surgical procedure , an implanted device , or an ingestible substance .