***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: The development of  stimulus selectivity in the primary sensory cortex of higher vertebrates is considered in a general mathematical framework . A synaptic evolution scheme of a new kind is proposed in which incoming patterns rather than converging afferents compete . The change in the efficacy of a given synapse depends not only on instantaneous pre- and postsynaptic activities but also on a slowly varying time-averaged value of the postsynaptic activity . Assuming an appropriate nonlinear form for this dependence , development of selectivity is obtained under quite general conditions on the sensory environment . One does not require nonlinearity of the neuron 's integrative power nor does one need to assume any particular form for intracortical circuitry . This is first illustrated in simple cases , e.g. , when the environment consists of only two different stimuli presented alternately in a r and om manner . The following formal statement then holds : the state of the system converges with probability 1 to points of maximum selectivity in the state space . We next consider the problem of early development of  orientation selectivity and binocular interaction in primary visual cortex . Giving the environment an appropriate form , we obtain orientation tuning curves and ocular dominance comparable to what is observed in normally reared adult cats or monkeys . Simulations with binocular input and various types of normal or altered environments show good agreement with the relevant experimental data . Experiments are suggested that could test our theory further Young ( ages 18 - 22 years ) and older ( ages 61 - 87 years ) adults ( N = 106 ) played the Virtual Week board game , which involves simulating common prospect i ve memory ( PM ) tasks of everyday life ( e.g. , taking medication ) , and performed working memory ( WM ) and vigilance tasks . The Virtual Week game includes regular ( repeated ) and irregular ( nonrepeated ) PM tasks with cues that are either more or less focal to other ongoing activities . Age differences in PM were reduced for repeated tasks , and performance improved over the course of the week , suggesting retrieval was more spontaneous or habitual . Correlations with WM within each age group were reduced for PM tasks that had more regular or focal cues . WM ( but not vigilance ) ability was a strong predictor of irregular PM tasks with less focal cues . Taken together , these results support the hypothesis that habitual and focally cued PM tasks are less dem and ing of attentional re sources ( specifically , WM ) , whereas tasks that are more dem and ing of controlled attentional processes produce larger age differences , which may be attributable to individual differences in WM Background : Repetitive transcranial magnetic stimulation over the left dorsolateral prefrontal cortex ( DLPFC ) has been documented to influence striatal and orbitofrontal dopaminergic activity implicated in reward processing . However , the exact neuropsychological mechanisms of how DLPFC stimulation may affect the reward system and how trait hedonic capacity may interact with the effects remains to be eluci date d. Objective : In this sham-controlled study in healthy individuals , we investigated the effects of a single session of neuronavigated intermittent theta burst stimulation ( iTBS ) on reward responsiveness , as well as the influence of trait hedonic capacity . Methods : We used a r and omized crossover single session iTBS design with an interval of 1 week . We assessed reward responsiveness using a rewarded probabilistic learning task and measured individual trait hedonic capacity ( the ability to experience pleasure ) with the temporal experience of pleasure scale question naire . Results : As expected , the participants developed a response bias toward the most rewarded stimulus ( rich stimulus ) . Reaction time and accuracy for the rich stimulus were respectively shorter and higher as compared to the less rewarded stimulus ( lean stimulus ) . Active or sham stimulation did not seem to influence the outcome . However , when taking into account individual trait hedonic capacity , we found an early significant increase in the response bias only after active iTBS . The higher the individual 's trait hedonic capacity , the more the response bias toward the rich stimulus increased after the active stimulation . Conclusion : When taking into account trait hedonic capacity , one active iTBS session over the left DLPFC improved reward responsiveness in healthy male participants with higher hedonic capacity . This suggests that individual differences in hedonic capacity may influence the effects of iTBS on the reward system This individual differences study examined the separability of three often postulated executive functions-mental set shifting ( " Shifting " ) , information updating and monitoring ( " Updating " ) , and inhibition of prepotent responses ("Inhibition")- and their roles in complex " frontal lobe " or " executive " tasks . One hundred thirty-seven college students performed a set of relatively simple experimental tasks that are considered to predominantly tap each target executive function as well as a set of frequently used executive tasks : the Wisconsin Card Sorting Test ( WCST ) , Tower of Hanoi ( TOH ) , r and om number generation ( RNG ) , operation span , and dual tasking .  Confirmatory factor analysis indicated that the three target executive functions are moderately correlated with one another , but are clearly separable . Moreover , structural equation modeling suggested that the three functions contribute differentially to performance on complex executive tasks . Specifically , WCST performance was related most strongly to Shifting , TOH to Inhibition , RNG to Inhibition and Updating , and operation span to Updating . Dual task performance was not related to any of the three target functions . These results suggest that it is important to recognize both the unity and diversity of executive functions and that latent variable analysis is a useful approach to study ing the organization and roles of executive functions Prospect i ve memory ( PM ) refers to a complex cognitive ability that underpins the delayed execution of previously formulated intentions . PM performance declines early in normal aging and this process is accentuated in Alzheimer 's disease . The left frontopolar cortex ( BA10 ) has been consistently assigned a major role in PM functioning , but whether it can be noninvasively modulated to enhance PM performance in aged people has not been addressed so far . Here , we investigated the effects of modulating left BA10 by means of theta burst stimulation ( TBS ) , using either excitatory ( intermittent TBS ) , inhibitory ( continuous TBS ) or control ( vertex ) TBS in healthy aged subjects . The behavioral effects were assessed using a reliable and ecological virtual reality PM task that included both event- and time-based retrievals . As compared with vertex stimulation , event-based PM performance significantly improved after excitatory stimulation , whereas inhibitory stimulation had no significant effect . Additionally , and across the different types of stimulation , performance for congruent links between the event-based PM cue and the action to be performed was significantly better as compared with incongruent links . In conclusion , intermittent TBS might provide a relevant interventional strategy to counteract the decline of cognitive functions and memory abilities in normal aging Dopamine is implicated in movement , learning , and motivation , and in illnesses such as Parkinson 's disease , schizophrenia , and drug addiction . Little is known about the control of dopamine release in humans , but research in experimental animals suggests that the prefrontal cortex plays an important role in regulating the release of dopamine in subcortical structures . Here we used [(11)C]raclopride and positron emission tomography to measure changes in extracellular dopamine concentration in vivo after repetitive transcranial magnetic stimulation ( rTMS ) of the dorsolateral prefrontal cortex in healthy human subjects . Repetitive TMS of the left dorsolateral prefrontal cortex caused a reduction in [(11)C]raclopride binding in the left dorsal cau date nucleus compared with rTMS of the left occipital cortex . There were no changes in binding in the putamen , nucleus accumbens , or right cau date . This shows that rTMS of the prefrontal cortex induces the release of endogenous dopamine in the ipsilateral cau date nucleus . This finding has implication s for the therapeutic and research use of rTMS in neurological and psychiatric disorders It has been 30 years since the discovery that repeated electrical stimulation of neural pathways can lead to long-term potentiation in hippocampal slices . With its relevance to processes such as learning and memory , the technique has produced a vast literature on mechanisms of synaptic plasticity in animal models . To date , the most promising method for transferring these methods to humans is repetitive transcranial magnetic stimulation ( rTMS ) , a noninvasive method of stimulating neural pathways in the brain of conscious subjects through the intact scalp . However , effects on synaptic plasticity reported are often weak , highly variable between individuals , and rarely last longer than 30 min . Here we describe a very rapid method of conditioning the human motor cortex using rTMS that produces a controllable , consistent , long-lasting , and powerful effect on motor cortex physiology and behavior after an application period of only 20 - 190 The present study aim ed to investigate the role of frontopolar cortex in prospect i ve memory ( PM ) by means of inhibitory theta-burst stimulation ( cTBS ) . " Experiment 1"-8 volunteers were evaluated after inhibitory cTBS over left Brodmann area ( BA ) 10 , right BA10 , and Cz . In the PM procedure , sequences of 4 words each were presented . During the intersequence delay , subjects had to repeat the sequence in the observed order ( ongoing task forward ) or in the reverse order ( backward ) . At the occurrence of a target word , subjects had to press a key on the keyboard ( PM task ) . Recall and recognition of the target words were also tested . PM accuracy was lower after cTBS over left BA10 compared with Cz ( P = 0.012 ) , whereas it was comparable in right BA10 and Cz conditions . No other significant differences between the 3 conditions were found . " Experiment 2"-8 subjects were administered the same experimental PM procedure as above after inhibitory cTBS over left BA46 and Cz . In this case , none of the tested effects were significant . Our findings corroborate the hypothesis that within the prefrontal cortex , the left BA10 is specifically involved in the mediation of processes related to the execution of delayed intentions The involvement of frontopolar cortex in mediating prospect i ve memory processes has been evidence d by various studies , mainly by means of neuroimaging techniques . Recently , one transcranial magnetic stimulation study documented that transient inhibition of left Brodmann Area ( BA ) 10 impaired verbal prospect i ve memory . This result raises the issue of whether the BA 10 involvement in prospect i ve memory functioning may be modulated by the physical characteristics of the stimuli used . The present study aim ed to investigate the role of the frontopolar cortex in visual-spatial PM by means of the application of inhibitory theta-burst stimulation .  Twelve volunteers were evaluated after inhibitory theta-burst stimulation over left BA 10 , right BA10 and CZ ( control condition ) . In the prospect i ve memory procedure , sequences of four spatial positions ( black squares ) each were presented . During the inter-sequence delay , subjects had to reproduce the sequence in the observed order ( ongoing task forward ) or the reverse order ( backward ) . At the occurrence of a target position , subjects had to press a key on the keyboard ( prospect i ve memory score ) . Recall and recognition of the target positions were also tested . We found that prospect i ve memory accuracy was lower after theta-burst stimulation over right BA10 than CZ ( p<0.01 ) , whereas it was comparable in left BA10 and CZ conditions . No significant difference was found among the three conditions on recall and recognition of target positions and on ongoing task performance . Our findings provide a novel strong evidence for a specific involvement of right frontopolar cortex in visual-spatial prospect i ve memory . In the context of previous data providing evidence for left BA 10 involvement in verbal prospect i ve memory , our results also suggest material -specific lateralization of prospect i ve memory processes in BA 10 Although previous studies have shown that the rostral prefrontal cortex ( rPFC ) plays a crucial role in executive tasks , the various functions of the rPFC in the humans are still understudied . Here we used transcranial magnetic stimulation ( TMS ) with continuous theta burst stimulation ( cTBS ) to interfere with the executive control functions of the right rostrolateral PFC ( RLPFC ) or the right rostromedial PFC ( RMPFC ) . Subjects performed a task-switching paradigm , which included spatial detection ( SD ) , prospect i ve memory ( PM ) and working memory ( WM ) tasks , after cTBS . The performance of 18 healthy volunteers was evaluated on different days after cTBS over the right RLPFC , the right RMPFC , and the vertex ( serving as a control site ) . The application of cTBS over the RLPFC significantly increased the switching costs ( SCs ) of the error rates ( ERs ) when switching to the PM task , while RMPFC-cTBS decreased SCs of ERs when switching to the WM task , compared with the control vertex site . These findings provide evidence for a differential role of the RLPFC and the RMPFC in executive functions , with a specific involvement of the RLPFC and the RMPFC in PM , and WM , respectively The brain-derived neurotrophic factor gene ( BDNF ) is one of many genes thought to influence synaptic plasticity in the adult brain and shows a common single nucleotide polymorphism ( BDNF Val66Met ) in the normal population that is associated with differences in hippocampal volume and episodic memory . It is also thought to influence possible synaptic changes in motor cortex following a simple motor learning task . Here we extend these studies by using new non-invasive transcranial magnetic stimulation ( TMS ) and transcranial direct current stimulation ( TDCS ) techniques that directly test the excitability and plasticity of neuronal circuits in human motor cortex in subjects at rest . We investigated whether the susceptibility to TMS probes of plasticity is significantly influenced by the BDNF polymorphism . Val66Met carriers were matched with Val66Val individuals and tested on the following protocol s : continuous and intermittent theta burst TMS ; median nerve paired associative stimulation ; and homeostatic plasticity in the TDCS/1 Hz rTMS model . The response of Met allele carriers differed significantly in all protocol s compared with the response of Val66Val individuals . We suggest that this is due to the effect of BNDF on the susceptibility of synapses to undergo LTP/LTD . The circuits tested here are implicated in the pathophysiology of movement disorders such as dystonia and are 
    Output:
    
A systematic review of iTBS studies revealed variability in reliability of effects though most were in the theorized direction .
TBS protocol s appear to be effective in modulating prefrontal cortical excitability in previously theorized directions .
HIGHLIGHTSPrefrontal cTBS has a significant attenuating effect on executive functions .
The cognitive effects of prefrontal iTBS are mostly in the theorized direction .
These data suggest that TBS is a reliable means of modulating prefrontal activity