Separable neuronal circuitries for manipulable and non-manipulable objects in working memory.

Differential Neural Activation for Updating Rule versus Stimulus Information in Working Memory

Effective connectivity within the neural system for object-directed action representation during aware and unaware tool processing

Patients with schizophrenia exhibit impairments in working memory that often appear in attenuated form in persons at high risk for the illness. The authors hypothesized that deviations in task-related brain activation and deactivation would occur in persons with an at-risk mental state performing a working memory task that entailed the maintenance and manipulation of letters. Participants at ultra high risk for developing psychosis (N=60), identified using the Comprehensive Assessment of At-Risk Mental States, and healthy comparison subjects (N=38) 14 to 29 years of age underwent functional MRI while performing a verbal working memory task. Group differences in brain activation were identified using analysis of covariance. The two groups did not show significant differences in speed or accuracy of performance, even after accounting for differences in education. Irrespective of task condition, at-risk participants exhibited significantly less activation than healthy comparison subjects in the left anterior insula. During letter manipulation, at-risk persons exhibited greater task-related deactivation within the default-mode network than comparison subjects. Region-of-interest analysis in the at-risk group revealed significantly greater right dorsolateral prefrontal cortex activation during manipulation of letters. Despite comparable behavioral performance, at-risk participants performing a verbal working memory task exhibited altered brain activation compared with healthy subjects. These findings demonstrate an altered pattern of brain activation in at-risk persons that contains elements of reduced function as well as compensation.

In children, the importance of detecting deficits after mild traumatic brain injury (mTBI) or concussion has grown with the increasing popularity of leisure physical activities and contact sports. Whereas most postconcussive symptoms (PCS) are similar for children and adults, the breadth of consequences to children remains largely unknown. To investigate the effect of mTBI on brain function, we compared working memory performance and related brain activity using blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in 15 concussed youths and 15 healthy age-matched control subjects. Neuropsychological tests, self-perceived PCS, and levels of anxiety and depression were also assessed. Our results showed that, behaviorally, concussed youths had significantly worse performances on the working memory tasks, as well as on the Rey figure delayed recall and verbal fluency. fMRI results revealed that, compared to healthy children, concussed youths had significantly reduced task-related activity in bilateral dorsolateral prefrontal cortex, left premotor cortex, supplementary motor area, and left superior parietal lobule during performance of verbal and nonverbal working memory tasks. Additionally, concussed youths also showed less activation than healthy controls in the dorsal anterior cingulate cortex, left thalamus, and left caudate nucleus during the nonverbal task. Regression analysis indicated that BOLD signal changes in bilateral dorsolateral prefrontal cortex were significantly correlated with performance such that greater activities in these regions, relative to the control condition, were associated with greater accuracy. Our findings confirmed functional alterations in brain activity after concussion in youths, a result similar to that observed in adults. However, significant differences were noted. In particular, the observation of reduced working memory accuracy suggests that youths may be unable to engage compensatory strategies to maintain cognitive performance after mTBI. This has significant implications for safe return to daily activities, including competitive sport.

Background: The underlying brain mechanisms of altered cognitive function associated with adjuvant chemotherapy for breast cancer, commonly designated “chemobrain”, have yet to be determined. Recent research indicates that compromised cognitive function may already exist prior to treatment, adding to the complexity of determining the true impact of adjuvant chemotherapy on brain function. We examined whether two common symptoms associated with breast cancer diagnosis, worry and fatigue, might influence neurocognitive responses during functional magnetic resonance imaging (fMRI) before adjuvant therapy. Methods: Seventy five women (29–75 years) awaiting either adjuvant chemotherapy (n=25) or radiation therapy (n=25) for localized breast cancer and age-matched controls without breast cancer (n=25) were enrolled. Participants performed a verbal working memory task (VWMT) with varying levels of demand for cognitive control during fMRI scanning and provided self-reports of worry and fatigue after scanning. Imaging data were analyzed using the general linear model implemented in SPM5; comparative statistics were used to determine group differences in self-report and behavioral measures. Results: In general, the pre-chemotherapy group showed compromised cognitive functioning relative to the other groups. Specifically, they reported higher worry than the pre-radiation therapy (p=.036) and control (p=.047) groups. The pre-chemotherapy group also identified greater fatigue than controls (p=.04); the pre-radiation group reported a fatigue level between the other two groups. In the VWMT, the pre-chemotherapy group was less accurate than controls (p=.05), while the mean accuracy for the pre-radiation group again fell between these two groups. fMRI results showed that the control group selectively increased recruitment of executive control brain regions including the left inferior frontal gyrus (LIFG) and the anterior cingulate cortex (ACC) in response to high vs. low demand conditions. However, recruitment of LIGF and ACC by the control group was greater than that by both the pre-chemotherapy (p=.01 and p=.003 respectively) and the pre-radiation groups (p=.027 and p=.02 respectively). Overall, higher fatigue was correlated with failure to increase recruitment of the LIFG and ACC in high vs. low demand conditions (p=.002 and p=.078 respectively). Greater worry was correlated with failure to suppress task-irrelevant activation of default network regions, particularly the posterior cingulate cortex, in high vs. low demand conditions, and with lower accuracy in the VWMT (p=.01). Thus, fatigue and worry made independent contributions to altered neurocognitive responses prior to any adjuvant treatment. Discussion: These findings suggest that women awaiting adjuvant chemotherapy are vulnerable to compromised cognitive functioning, specifically in the domains of attention and working memory, related to higher worry and fatigue. Worry and fatigue may contribute to the cognitive impact often attributed to adjuvant chemotherapy. Therapeutic interventions to counteract worry and fatigue hold potential for optimizing cognitive function prior to adjuvant treatment for breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD04-08.

Stimulus-dependent modulation of working memory for identity monitoring: A functional MRI study

Decoding verbal working memory representations of Chinese characters from Broca's area

Functional heterogeneity within Broca's area during verbal working memory

Distinct neural correlates of associative working memory and long-term memory encoding in the medial temporal lobe

We used 15O-labelled water in a PET study to test the efficiency of cochlear implants (CIs) in transmitting auditory information to the brain in 10 profoundly deaf subjects. Five were postlingually deaf, and five were prelingually deaf. All the subjects were right-handed. White noise and verbal stimuli, delivered through the CIs, were used for cortical activation. Similar tasks were performed by six right-handed hearing subjects as a control group. In the postlingually deaf subjects, verbal stimulation activated the transverse temporal gyri (primary auditory cortices) mainly on the side contralateral to the CI. The left posterior superior temporal gyrus (Wernicke's area), and the left inferior frontal gyrus (Broca's area) were also activated irrespective of stimulated side. The location of these activated foci was the same as that of the control group. White noise stimulation led to an increase of regional cerebral blood flow (rCBF) only in the primary auditory cortices of the postlingually deaf subjects, only on the side contralateral to the CI, and the intensity of activation was less than that obtained with verbal stimulation. In the prelingually deaf subjects, Wernicke's area and Broca's area were significantly activated by verbal stimulation, whereas there was no activation in the primary auditory cortices. White noise did not activate the primary auditory cortex in the prelingually subjects. These findings suggest that cortical representation of language is not dependent on early auditory experience, while processing in the primary auditory cortices is experience-dependent. The postlingually deaf subjects had a greater increase of rCBF in the Broca's and Wernicke's areas and better sentence comprehension than the prelingually deaf subjects, which suggest a parallel relation between rCBF increase and the ability to recognize spoken language. H2(15)O-PET with auditory stimulation is an effective means of objectively quantifying the response of auditory and association cortices after CIs in deaf subjects.

Voxel-Based Morphometry Reveals Increased Gray Matter Density in Broca's Area in Male Symphony Orchestra Musicians

OPINION article Front. Hum. Neurosci., 09 December 2011Sec. Cognitive Neuroscience volume 5 - 2011 | https://doi.org/10.3389/fnhum.2011.00162

Aim: In this manuscript, we report data on the association between executive functions screened by Frontal Assessment Battery, Five Digit Test and Digit Span with self-reported depressive symptoms and sleep complaints in non-demented older adults.Methods: A total sample of 95 non-demented older adults performed Geriatric Depression Scale short version, Frontal Assessment Battery, Five Digit Test, Digit Span, and clinical interview. We split participants in groups stratified by age according to: young-old (60–69 years of age), old-old (70–79 years), and oldest-old (>80 years) and compared these three groups on the sociodemographic characteristics and executive functions performance. We carried out Poisson regression with robust error variance to verify sleep complaints and depression effects on executive functions performance. Gender, age, years of formal education, use of antidepressants and of benzodiazepines were considered as confounding variables, taking into account executive functions as dependent and sleep complaints and depression as independent variables.Results: Controlling the effect of age, gender, years of formal education, use of benzodiazepines and of antidepressants there was a significant influence of depression in motor programming, inhibitory control, and working memory. Individuals without depression show motor programming scores 68.4% higher, inhibitory control scores 3 times greater and working memory scores also 3 times greater than individuals without depression. There was a significant influence of sleep complaints in phonemic fluency, motor programming, inhibitory control, and working memory. Individuals without sleep complaints show phonemic fluency scores 2 times greater than, motor programming scores 85.9% higher, inhibitory control scores 3 times greater and working memory scores also 3 times greater than individuals without sleep complaints.Conclusions: Sleep complaints are associated with phonemic fluency, motor programming, inhibitory control, and working memory impairment. Depression symptoms presence are associated with motor programming and working memory performances. Depression and sleep complaints interaction would determine worse phonemic fluency, inhibitory control and working memory cognitive performance than these two conditions alone.

A functional magnetic resonance imaging study of mental subtraction in human subjects

Risperidone and Divalproex Differentially Engage the Fronto-Striato-Temporal Circuitry in Pediatric Mania: A Pharmacological Functional Magnetic Resonance Imaging Study