| Pituitary tumors are the most common intracranial tumors following the meningioma,accounting for about 16.5%of central nervous system tumors(CNS).More than 50%of pituitary adenomas will overproduce one or more specific hormones,and these tumors are clinically called secretory pituitary adenomas or functional pituitary adenomas.Even if the size of these functional pituitary adenomas are small,their excessive secretion of hormones can cause endocrine disorders and then affect body functions.In recent decades,the combination of drug therapy,radiotherapy,and surgical intervention has significantly improved the treatment effect of pituitary adenomas.However,some studies have found that even pituitary adenoma patients who have recovered from this disease still have persistent cognitive dysfunction,which seriously affects the normal life.In particular,the dysfunctions of executive control and attention processing are important influences that affect the patients’ daily life.Therefore,the recovery standard of patients with pituitary adenoma is unscientific only depending on the hormone and MRI assessment.It is essential to explore the cognitive dysfunctions in these patients,especially the executive control and attention processing.Generally,this study mainly tried to explore these patients’ cognitive deficits and the potential neural mechanisms by integrating abnormal endogenous hormone levels with nerve electrophysiology.The main research is mainly conducted through the following four parts:Part Ⅰ:In this part,we employ an event-related potentials(ERPs)technique to quantitatively assess response activation and inhibition before and after the surgical treatment of prolactinomas.We identified P300 across all study populations that could reflect response activation and inhibition.Across the three groups,the Nogo stimuli evoked larger frontal-central P300 than the Go stimuli did.In contrast,the Go trials elicited larger parietal P300 than the Nogo trials did.The peak latency of P300 was significantly delayed in both the pre-operative and the post-operative groups compared to the HCs.The amplitude of P300 in both the Go and the Nogo conditions was significantly decreased in the pre-operative patients compared with that of the HCs.At 6 months post-operatively,the prolactinoma patients showed an increase in amplitude of P300 during both the Go and the Nogo tasks.These findings indicate that the prolactinoma patients suffer from deficits in response activation and inhibition,which could be improved by surgical treatment.Part Ⅱ:Except for the executive controls in daily life,the attention processing also plays a pivotal role in the cognitive process.The study aims to identify the electrophysiological change that relates to attention processing in pituitary patients before and after treatment.Across three groups(preoperative pituitary,postoperative pituitary patients and healthy participants),all emotional stimuli evoked P200 components.Compared with the HCs or postoperative patients,the amplitudes of P200 in the preoperative patients were higher.Moreover,The amplitudes of P200 decreased in the postoperative patients,which were similar to that in the HCs.The attention processing was improved after surgery,but no signifificant differences were detected between the postoperative patients and HCs.Compared with that of the HCs and postoperative patients,the P200 component elicited by negative stimuli is higher in preoperative patients,which may illustrate compensatory activity after.attention impairments.Furthermore,these data indicate that improvements in attention processing may be attributed to the amelioration of endocrine disorders.Part Ⅲ:This study has demonstrated prolactinomas show the impaired executive controls.Because these parts mainly focused on.the broad-band Event-related potentials(ERPs)which only reflect the phase-locked neural activity evoked by the stimuli.Event-related neural oscillations at different frequency bands could provide more information.Oscillatory activity at distinct frequencies is associated with a variety of cognitive functions.Therefore,the relationship between neural oscillations related to inhibitory control and prolactin levels is still not very clear.Compared to the HCs,the patients demonstrated worse performance and their prolactin levels negatively correlated with behavioral results.Meanwhile,patients,P300 amplitudes in the Go and Nogo conditions were smaller than the HCs.The amplitudes of N200nogo in patients were smaller than the HCs as well.Lower frontal theta power was found in the patients than the HCs in both Go and Nogo conditions,which indicated a deficit in response activation and inhibition.Moreover,the PRL levels mediated the relationship between frontal theta power and behavior performance,implying that lower frontal theta power caused the dysfunction of response control by abnormally high PRL levels.Patients also showed lower occipital alpha power than the HCs,which suggested that the impaired response inhibition may arise from deficient attention control.The third part has confirmed the impaired attention processing also appear in these patients.Taken together,the present study revealed the neurocognitive discrepancies between prolactinomas and the HCs.The frontal theta oscillation was highlighted as the electrophysiological markers of the impaired response control in prolactinomas.Part Ⅳ:The second part of this research confirms that patients with pituitary adenoma have impairments in attention processing.Although the results showed that there was no significant correlation between serum hormones and P200 amplitude,there was a marginally significant correlation between the level of prolactin and P200 amplitude.Brain injury models have confirmed the correlation between cognitive functions and specific brain regions,but this chapter will mainly focus on whether there are abnormalities in the network of attention processing in prolactinomas.Compared with the HCs,larger frontoparietal theta and alpha coherence were found in the patients,especially in the right-lateralized hemisphere,which indicated a deficit in attention processing.Moreover,the frontoparietal coherence was positively correlated with altered prolactin levels,implying the significance of prolactin for adaptive brain compensation in prolactinomas.Taken together,this research showed the variations in attention processing between the HCs and prolactinomas.In summary,this experiment uses event-related potentials,event-related neural oscillations and event-related phase coherence to explore the relationship between the patients’ executive control,attention processing as well as the brain networks and the level of endogenous hormones,respectively.These findings reveal the neural mechanisms of executive control and attention processing from the perspective of information processing in the brain,thereby providing a method for clinical evaluation of the disease state of patients with pituitary adenoma,which can be convenient and effective cognition monitoring indicators. |
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