***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Post-traumatic stress disorder ( PTSD ) is a condition which can develop from exposure to a severe traumatic event such as those occurring during wars or natural disasters . Benzodiazepines and selective serotonin reuptake inhibitors ( SSRIs ) are considered the gold st and ard for PTSD treatment , but their side effects pose a serious problem . While regular physical exercise is regarded as a mood elevator and known to enhance cognitive function , its direct role in rescuing core symptoms of PTSD including anxiety and depression-like behaviors and cognitive impairment is unclear . In the present study using the single-prolonged stress ( SPS ) rat model of PTSD ( 2h restrain , 20 min forced swimming , 15 min rest , and 1 - 2 min diethyl ether exposure ) , we examined the beneficial effect of moderate treadmill exercise on SPS-induced behavioral deficits including anxiety and depression-like behaviors and memory impairment .  Male Wistar rats were r and omly assigned into four groups : control ( sedentary ) , exercised , SPS ( no exercise ) , or SPS-exercised . Rats were exercised on a rodent treadmill for 14 consecutive days . Rats in all groups were tested for anxiety-like behaviors using open field ( OF ) , light-dark and elevated-plus maze tests . All rats were tested for short-term and long-term memory in the radial arm water maze test . Rats were then sacrificed , blood was collected ( for corticosterone levels ) , and individual organs ( spleen , adrenals , and thymus ) harvested . Results suggest that moderate physical exercise ameliorates SPS-induced behavioral deficits in rats ABSTRACT Although colloquial wisdom and some studies suggest an association between regular aerobic exercise and emotional well-being , the nature of this link remains poorly understood . We hypothesised that aerobic exercise may change the way people respond to their emotions . Specifically , we tested whether individuals experiencing difficulties with emotion regulation would benefit from a previous session of exercise and show swifter recovery than their counterparts who did not exercise . Participants ( N = 80 ) completed measures of emotion response tendencies , mood , and anxiety , and were r and omly assigned to either stretch or jog for 30 minutes . All participants then underwent the same negative and positive mood inductions , and reported their emotional responses . Analyses showed that more perceived difficulty generating regulatory strategies and engaging in goal -directed behaviours after the negative mood induction predicted more intense and persistent negative affect in response to the stressor , as would be expected . Interactions revealed that aerobic exercise attenuated these effects . Moderate aerobic exercise may help attenuate negative emotions for participants initially experiencing regulatory difficulties . This study contributes to the literature on aerobic exercise ’s therapeutic effects with experimental data , specifically in the realm of emotional processing Previous results indicated that stress impairs learning and memory . In this research , the effects of preventive , therapeutic and regular continually running activity on  chronic stress-induced memory deficit in rats were investigated . 70 male rats were r and omly divided into seven groups as follows : Control , Sham , Stress-Rest , Rest-Stress , Stress-Exercise , Exercise-Stress and Exercise-Stress & Exercise groups . Chronic restraint stress was applied 6 h/day for 21days and treadmill running 1 h/day .  Memory function was evaluated by the passive avoidance test . The results revealed that running activities had therapeutic effect on mid and long-term memory deficit and preventive effects on short and mid-term memory deficit in stressed rats . Regular continually running activity improved mid and long-term memory compared to Exercise-Stress group . The beneficial effects of exercise were time-dependent in stress conditions . Finally , data corresponded to the possibility that treadmill running had a more important role on treatment rather than on prevention on memory impairment induced by stress Despite the important role that attending to novel events plays in human behavior , there is limited information about the neuroanatomical underpinnings of this vital activity . This study investigated the relative contributions of the frontal and posterior parietal lobes to the differential processing of novel and target stimuli under an experimental condition in which subjects actively directed attention to novel events . Event-related potentials were recorded from well-matched frontal patients , parietal patients , and non-brain-injured subjects who controlled their viewing duration ( by button press ) of line drawings that included a frequent , repetitive background stimulus , an infrequent target stimulus  , and  infrequent , novel visual stimuli . Subjects also responded to target stimuli by pressing a foot pedal . Damage to the frontal cortex result ed in a much greater disruption of response to novel stimuli than to design ated targets . Frontal patients exhibited a widely distributed , profound reduction of the novelty P3 response and a marked diminution of the viewing duration of novel events . In contrast , damage to posterior parietal lobes was associated with a substantial reduction of both target P3 and novelty P3 amplitude ; however , there was less disruption of the processing of novel than of target stimuli . We conclude that two nodes of the neuroanatomical network for responding to and processing novelty are the prefrontal and posterior parietal regions , which participate in the voluntary allocation of attention to novel events . Injury to this network is indexed by reduced novelty P3 amplitude , which is tightly associated with diminished attention to novel stimuli . The prefrontal cortex may serve as the central node in determining the allocation of attentional re sources to novel events , whereas the posterior parietal lobe may provide the neural substrate for the dynamic process of updating one 's internal model of the environment to take into account a novel event Purpose Impairment of learning and memory processes has been demonstrated by many studies using different stressors . Other reports suggested that exercise has a powerful behavioral intervention to improve cognitive function and brain health . In this research , we investigated protective effects of treadmill running on  chronic stress – induced memory deficit in rats . Methods Fifty male Wistar rats were r and omly divided into five groups ( n=10 ) as follows : Control ( Co ) , Sham ( Sh ) , Stress ( St ) , Exercise ( Ex ) and Stress and Exercise ( St & Ex ) groups . Chronic restraint stress was applied by 6h/day/21days and also treadmill running at a speed 20 - 21m/min for 1h/day/21days . Memory function was evaluated by the passive avoidance test in different intervals ( 1 , 7 and 21 days ) after foot shock . Results Our results showed that : 1 ) Although exercise alone showed beneficial effects especially on short and mid-term memory ( P<0.05 ) in comparison with control group , but synchronized exercise with stress had not significantly improved short , mid and long-term memory deficit in stressed rats . 2 ) Short and mid-term memory deficit was significantly ( P<0.05 ) observed in synchronized exercise with stress and stress groups with respect to normal rats . 3 ) Memory deficit in synchronized exercise with stress group was nearly similar to stressed rats . 4 ) Helpful effects of exercise were less than harmful effects of stress when they were associated together . Conclusion The data correspond to the possibility that although treadmill running alone has helpful effects on learning and memory consolidation , but when it is synchronized with stress there is no significant benefit and protective effects in improvement of memory deficit induced by chronic stress . However , it is has a better effect than no training on memory deficit in stressed rats Psychological stress , induced by the Trier Social Stress Test ( TSST ) , has repeatedly been shown to alter memory performance . Although factors influencing memory performance such as stimulus nature ( verbal/pictorial ) and emotional valence have been extensively studied , results whether stress impairs or improves memory are still inconsistent . This study aim ed at exploring the effect of TSST on item versus associative memory for neutral , verbal , and pictorial stimuli . 48 healthy subjects were recruited , 24 participants were r and omly assigned to the TSST group and the remaining 24 participants were assigned to the control group .  Stress reactivity was measured by psychological ( subjective state anxiety ratings ) and physiological ( Galvanic skin response recording ) measurements . Subjects performed an item-association memory task for both stimulus types ( words , pictures ) simultaneously , before , and after the stress/non-stress manipulation . The results showed that memory recognition for pictorial stimuli was higher than for verbal stimuli . Memory for both words and pictures was impaired following TSST ; while the source for this impairment was specific to associative recognition in pictures , a more general deficit was observed for verbal material , as expressed in decreased recognition for both items and associations following TSST . Response latency analysis indicated that the TSST manipulation decreased response time but at the cost of memory accuracy . We conclude that stress does not uniformly affect memory ; rather it interacts with the task ’s cognitive load and stimulus type . Applying the current study results to patients diagnosed with disorders associated with traumatic stress , our findings in healthy subjects under acute stress provide further support for our assertion that patients ’ impaired memory originates in poor re collection processing following depletion of attentional re sources 1 . Hazelrigg , T. Cell 95 , 451–460 ( 1998 ) . 2 . Tiedge , H. , Bloom , F. E. & Richter , D. Science 283 , 186–187 ( 1999 ) . 3 . Huang , E. P. Curr . Biol . 9 , R168–R170 ( 1999 ) . 4 . Gao , F. B. Bioessays 20 , 7–78 ( 1998 ) . 5 . Kuhl , D. & Skehel , P. Curr . Opin . Neurobiol . 8 , 600–606 ( 1998 ) . 6 . Palade , G. Science 189 , 347–358 ( 1975 ) . 7 . Spacek , J. & Harris , K. M. J. Neurosci 17 , 190–203 ( 1997 ) . 8 . Berridge , M. J. Neuron 21 , 13–26 ( 1998 ) . 9 . Matlack , K. E. S. , Mothes , W. & Rapoport , T. A. Cell 92 , 381–390 ( 1998 ) . 10 . Gorlich , D. & Rapoport , T. A. Cell 75 , 615–630 ( 1993 ) . 11 . Bailey , C. H. , Bartsch , D. & K and el , E. R. Proc . Natl . Acad . Sci . USA 93 , 13445–13452 ( 1996 ) . 12 . Schuman , E. M. Neuron 18 , 339–342 ( 1997 ) . 13 . Pelham , H. R. Trends . Biochem . Sci . 15 , 483–486 ( 1990 ) . 14 . Lledo , P.M. , Zhang , X. , Sudhof , T. C. , Malenka , R. C. & Nicoll , R. A. Science 279 , 399–403 ( 1998 ) . 15 . Chan , J. , Aoki , C. & Pickel , V. M. J. Neurosci . Methods 33 , 113–127 ( 1990 ) . brief communications Memory impairment is commonly noted in stroke survivors , and can lead to delay of functional recovery . Exercise has been proved to improve memory in adult healthy subjects . Such beneficial effects are often suggested to relate to hippocampal synaptic plasticity , which is important for memory processing . Previous evidence showed that in normal rats , low intensity exercise can improve synaptic plasticity better than high intensity exercise . However , the effects of exercise intensities on hippocampal synaptic plasticity and spatial memory after brain ischemia remain unclear . In this study , we investigated such effects in brain ischemic rats . The middle cerebral artery occlusion ( MCAO ) procedure was used to induce brain ischemia . After the MCAO procedure , rats were r and omly assigned to sedentary ( Sed ) , low-intensity exercise ( Low-Ex ) , or high-intensity exercise ( High-Ex ) group . Treadmill training began from the second day post MCAO procedure , 30 min/day for 14 consecutive days for the exercise groups . The Low-Ex group was trained at the speed of 8 m/min , while the High-Ex group at the speed of 20 m/min . The spatial memory , hippocampal brain-derived neurotrophic factor ( BDNF ) , synapsin-I , postsynaptic density protein 95 ( PSD-95 ) , and dendritic structures were examined to document the effects . Serum corticosterone level was also quantified as stress marker . Our results showed the Low-Ex group , but not the High-Ex group , demonstrated better spatial memory performance than the Sed group . Dendritic complexity and the levels of BDNF and PSD-95 increased significantly only in the Low-Ex group as compared with the Sed group in bilateral hippocampus . Notably , increased level of corticosterone was found in the High-Ex group , implicating higher stress response . In conclusion , after brain ischemia , low intensity exercise may result in better synaptic plasticity and spatial memory performance than high intensity exercise ; therefore , the intensity is suggested to be considered during exercise training RATIONALE Exposure to intermittent hypoxia ( IH ) , such as occurs in sleep-disordered breathing , is associated with substantial cognitive impairments , oxidative stress and inflammation , and increased neuronal cell losses in brain regions underlying learning and memory in rats .  Physical activity ( PA ) is now recognized as neuroprotective in models of neuronal injury and degeneration . OBJECTIVES To examine whether PA will ameliorate IH-induced deficits . METHODS Young adult Sprague-D 
    Output:
    
Within animal models , chronic stress is associated with memory impairment and chronic exercise has both a preventive and therapeutic effect in attenuating stress-induced memory impairment .