Neural Correlates Of Verbal Memory Research Articles

Memory performance predicts response to psychotherapy for depression in bipolar disorder: A pilot randomized controlled trial with exploratory functional magnetic resonance imaging

ObjectiveThis pilot randomized controlled trial compared Cognitive Behavior Therapy (CBT) and Supportive Psychotherapy (SP) for the treatment of depression in bipolar I disorder. We also examined whether exploratory verbal memory, executive functioning, and neural correlates of verbal memory during functional magnetic resonance imaging (fMRI) predicted change in depression severity. MethodsThirty-two adults (ages 18–65) with DSM-IV bipolar I disorder meeting current criteria for a major depressive episode were randomized to 18 weeks of CBT or SP. Symptom severity was assessed before, at the mid-point, and after the 18-week intervention. All participants completed a brief pre-treatment neuropsychological testing battery (including the California Verbal Learning Test-2nd Edition, Delis Kaplan Executive Functioning System [DKEFS] Trail-making Test, and DKEFS Sorting Test), and a sub-set of 17 participants provided usable fMRI data while completing a verbal learning paradigm that consisted of encoding word lists. ResultsCBT and SP yielded comparable improvement in depressive symptoms from pre- to post-treatment. Better retention of learned information (CVLT-II long delay free recall vs. Trial 5) and recognition (CVLT-II hits) were associated with greater improvement in depression in both treatments. Increased activation in the left dorsolateral prefrontal cortex and right hippocampus during encoding was also related to depressive symptom improvement. LimitationsSample size precluded tests of clinical factors that may interact with cognitive/neural function to predict treatment outcome. ConclusionNeuropsychological assessment and fMRI offer additive information regarding who is most likely to benefit from psychotherapy for bipolar depression.

Neural correlates of verbal memory in youth with heavy prenatal alcohol exposure.

Prenatal alcohol exposure can impact both brain development and neurobehavioral function, including verbal learning and recall, although the relation between verbal recall and brain structure in this population has not been examined fully. We aimed to determine the structural neural correlates of verbal learning and recall in youth with histories of heavy prenatal alcohol exposure using a region of interest (ROI) approach. As part of an ongoing multisite project, subjects (age 10-16years) with prenatal alcohol exposure (AE, n=81) and controls (CON, n=81) were tested using the CVLT-C and measures of cortical volume, surface area, and thickness as well as hippocampal volume were derived from MRI. Group differences in brain and memory indices were tested with ANOVA. Multiple regression analyses tested whether brain ROIs significantly predicted memory performance. The AE group had lower scores than the CON group on all CVLT-C variables (ps≤.001) and volume and surface area (ps<.025), although results varied by ROI. No group differences in cortical thickness were found. The relations between cortical structure and memory performance differed between group among some ROIs, particularly those in the frontal cortex, generally with smaller surface area and/or thinner cortex predicting better performance in CON but worse performance in AE. Cortical surface area appears to be the most sensitive index to the effects of prenatal alcohol exposure, while cortical thickness appears to be the least sensitive. These findings also indicate that the neural correlates of verbal memory are altered in youth with heavy prenatal alcohol exposure compared to controls.

Right inferior frontal gyrus activation is associated with memory improvement in patients with left frontal low-grade glioma resection.

Patients with low-grade glioma (LGG) have been studied as a model of functional brain reorganization due to their slow-growing nature. However, there is no information regarding which brain areas are involved during verbal memory encoding after extensive left frontal LGG resection. In addition, it remains unknown whether these patients can improve their memory performance after instructions to apply efficient strategies. The neural correlates of verbal memory encoding were investigated in patients who had undergone extensive left frontal lobe (LFL) LGG resections and healthy controls using fMRI both before and after directed instructions were given for semantic organizational strategies. Participants were scanned during the encoding of word lists under three different conditions before and after a brief period of practice. The conditions included semantically unrelated (UR), related-non-structured (RNS), and related-structured words (RS), allowing for different levels of semantic organization. All participants improved on memory recall and semantic strategy application after the instructions for the RNS condition. Healthy subjects showed increased activation in the left inferior frontal gyrus (IFG) and middle frontal gyrus (MFG) during encoding for the RNS condition after the instructions. Patients with LFL excisions demonstrated increased activation in the right IFG for the RNS condition after instructions were given for the semantic strategies. Despite extensive damage in relevant areas that support verbal memory encoding and semantic strategy applications, patients that had undergone resections for LFL tumor could recruit the right-sided contralateral homologous areas after instructions were given and semantic strategies were practiced. These results provide insights into changes in brain activation areas typically implicated in verbal memory encoding and semantic processing.

Neural correlates of verbal memory encoding during semantic and structural processing tasks.

Eighteen participants were imaged using fMRI to explore whether brain regions predicting successful verbal memory encoding during semantic decisions would continue to predict encoding during structural (non-semantic) decisions. Consistent with prior studies, left inferior frontal and fusiform regions were more active during semantic than structural decisions, and activity was greater for remembered than forgotten words during semantic decisions. Critically, structural decisions yielded significantly greater activity for remembered than forgotten words in these regions providing evidence that a common frontal-temporal network supports verbal memory encoding irrespective of orienting task. Further analysis revealed activity associated with successful encoding in the right precentral gyrus, suggesting other regions may also play a role in verbal encoding during non-semantic processing.