Brain and Behavior

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation tool suited to alter cortical excitability and activity via the application of weak direct electrical currents. An increasing number of studies in the addiction literature suggests thattDCSmodulates subjective self‐reported craving through stimulation of dorsolateral prefrontal cortex (DLPFC). The major goal of this study was to explore effects of bilateralDLPFCstimulation on resting state networks (RSNs) in association with drug craving modulation. We targeted three large‐scaleRSNs; the default mode network (DMN), the executive control network (ECN), and the salience network (SN).

Fifteen males were recruited after signing written informed consent. We conducted a double‐blinded sham‐controlled crossover study. Twenty‐minute “real” and “sham”tDCS(2 mA) were applied over theDLPFCon two separate days in random order. Each subject received both stimulation conditions with a 1‐week washout period. The anode and cathode electrodes were located over the right and leftDLPFC, respectively. Resting statefMRIwas acquired before and after real and sham stimulation. Subjective craving was assessed before and after eachfMRIscan. TheRSNs were identified using seed‐based analysis and were compared using a generalized linear model.

Subjective craving decreased significantly after realtDCScompared to sham stimulation (p = .03). Moreover, the analysis shows significant modulation ofDMN,ECN, andSNafter realtDCScompared to sham stimulation. Additionally, alteration of subjective craving score was correlated with modified activation of the three networks.

Given the observed alteration of the targeted functional brain networks in methamphetamine users, new potentials are highlighted fortDCSas a network intervention strategy and rsfMRIas a suitable monitoring method for these interventions.

Perturbations in neural function provoked by a drug are thought to induce neural adaptations, which, in the absence of the drug, give rise to withdrawal symptoms. Previously published structural data from this study indicated that the progressive development of physical dependence is associated with increasing density of white matter tracts between the anterior cingulum bundle and the precuneus.

Using functional magnetic resonance imaging, we compared 11 smokers after 11 h of abstinence from nicotine and after satiation, with 10 nonsmoking controls, using independent component analysis for brain network comparisons as well as a whole brain resting‐state functional connectivity analysis using the anterior cingulate cortex as a seed.

Independent component analysis demonstrated increased functional connectivity in brain networks such as the default mode network associated with the withdrawal state in multiple brain regions. In seed‐based analysis, smokers in the withdrawal state showed stronger functional connectivity than nonsmoking controls between the anterior cingulate cortex and the precuneus, caudate, putamen, and frontal cortex (P < 0.05). Among smokers, compared to the satiated state, nicotine withdrawal was associated with increased connectivity between the anterior cingulate cortex and the precuneus, insula, orbital frontal gyrus, superior frontal gyrus, posterior cingulate cortex, superior temporal, and inferior temporal lobe (P < 0.02). The intensity of withdrawal‐induced craving correlated with the strength of connectivity between the anterior cingulate cortex and the precuneus, insula, caudate, putamen, middle cingulate gyrus, and precentral gyrus (r = 0.60–0.76; P < 0.05).

In concordance with our previous report that structural neural connectivity between the anterior cingulate area and the precuneus increased in proportion to the progression of physical dependence, resting‐state functional connectivity in this pathway increases during nicotine withdrawal in correlation with the intensity of withdrawal‐induced craving. These findings suggest that smoking triggers structural and functional neural adaptations in the brain that support withdrawal‐induced craving.

In previous imaging studies the insular cortex (IC) has been identified as an essential part of the processing of a wide spectrum of perception and sensorimotor integration. Yet, there are no systematic lesion studies in a sufficient number of patients examining whether processing of vestibular and the interaction of somatosensory and vestibular signals take place in the IC.

We investigated acute stroke patients with lesions affecting the IC in order to fill this gap. In detail, we explored signs of a vestibular tone imbalance such as the deviation of the subjective visual vertical (SVV). We applied voxel‐lesion behaviour mapping analysis in 27 patients with acute unilateral stroke.

Our data demonstrate that patients with lesions of the posterior IC have an abnormal tilt of SVV. Furthermore, re‐analysing data of 20 patients from a previous study, we found a positive correlation between thermal perception contralateral to the stroke and the severity of the SVV tilt.

We conclude that the IC is a sensory brain region where different modalities might interact.

Loss of hemispheric asymmetry during cognitive tasks has been previously demonstrated in the literature. In the context of language, increased right hemisphere activation is observed with aging. Whether this relates to compensation to preserve cognitive function or dedifferentiation implying loss of hemispheric specificity without functional consequence, remains unclear.

With a multifaceted approach, integrating structural and functional imaging data during a word retrieval task, in a group of younger and older adults with equivalent cognitive performance, we aimed to establish whether interactions between hemispheres or reorganization of dominant hemisphere networks preserve function. We examined functional and structural connectivity on data from our previously published functional activation study. Functional connectivity was measured using psychophysiological interactions analysis from the left inferior frontal gyrus (LIFG) and the left insula (LINS), based on published literature, and the right inferior frontal gyrus (RIFG) based on our previous study.

Although RIFG showed increased activation, its connectivity decreased with age. Meanwhile, LIFG and LINS connected more bilaterally in the older adults. White matter integrity, measured by fractional anisotropy (FA) from diffusion tensor imaging, decreased significantly in the older group. Importantly, LINS functional connectivity to LIFG correlated inversely with FA.

We demonstrate that left hemispheric language areas show higher functional connectivity in older adults with intact behavioral performance, and thus, may have a role in preserving function. The inverse correlation of functional and structural connectivity with age is in keeping with emerging literature and merits further investigation with tractography studies and in other cognitive domains.

Bell's palsy is a common neurological problem that leads to peripheral palsy of the facial nerve. Most patients have a favorable response with or without treatment while some are left with significant facial deformity. Identification of factors which influence the outcome in patients with Bell's palsy may help clinicians counsel better.

A prospective cross‐sectional study was carried out in the Department of Neurology Nobel Medical College, Biratnagar, between February 2020 and February 2021 after obtaining ethical clearance from the institutional review committee. Patients were assessed at the time of presentation to hospital and followed up at 1 week, 1 month, and 3 months after the onset of illness to evaluate for recovery.

Sixty‐two (61.4%) of 101 patients had a favorable outcome at the follow up on the third month, achieving H‐B grade 2 or lower, while 33 (32.7%) had moderate dysfunction and 6 (5.9%) had severe dysfunction. The following factors were associated with favorable outcome: younger age of onset (p < .001), lower initial H‐B grade of III or IV (p = .001), lesser degree of amplitude reduction on affected side as compared to unaffected side (p = .001) and absence of hypertension and diabetes. The following factors did not influence outcome at three months: duration of Bell's palsy (p = 0.142), side of face affected, and gender (p = .09).

Most of the patients with Bell's palsy have favorable outcomes. Age, hypertension, initial H‐B grade, and extent of facial nerve degeneration as recorded by nerve conduction studies are important predictors of outcome.

To compare the incidence and clinical features of individuals presenting in emergency rooms (ER) with facial palsy during the Italian COVID‐19 outbreak and in the same period of 2019.

We retrospectively reviewed the medical records for all accesses to the six ER in the province of Reggio Emilia, Italy, during the first phase of the COVID‐19 pandemic (27 February‐3 May 2020) to identify all cases of diagnosed facial palsy. Clinical information was retrieved for each patient and compared with that of facial palsy cases presenting in 2019.

Between 27 February and 3 May 2020, 38 patients presented to provincial ERs for facial palsy; in 2019, there were 22 cases, for an incidence rate ratio of 1.73 (95% CI 1.02–2.92) for the 2020 cohort. Of the 2020 cohort, eight patients (21%) presented with active or recent symptoms consistent with COVID‐19 infection, compared with 2 (9%) in 2019 (p = .299); one was tested and resulted positive for SARS‐CoV‐2. Moreover, patients were younger (−11 years, p = .037) than those of the previous year and manifested a longer lag (+1.1 days, p = .001) between symptoms onset and ER presentation.

We observed a higher occurrence of facial palsy during the COVID‐19 outbreak compared to the same period of the previous year; 21% of patients presenting with facial palsy had active or recent symptoms consistent with SARS‐CoV‐2 infection, suggesting an excess risk of facial palsy during or after COVID‐19. These patients searched for medical attention later, probably because of the fear of contracting COVID‐19 during assistance.

Clinically, Parkinson's disease (PD) presents with asymmetric motor symptoms. The left nigrostriatal system appears more susceptible to early degeneration than the right, and a left‐lateralized pattern of early neuropathological changes is also described in several neurodegenerative conditions, including Alzheimer's disease, frontotemporal dementia, and Huntington's disease. In this study, we evaluated hemispheric differences in estimated rates of atrophy in a large, well‐characterized cohort of PD patients.

Our cohort included 205 PD patients who underwent clinical assessments and T1‐weighted brain MRI's. Patients were classified into Early (n = 109) and Late stage (n = 96) based on disease duration, defined as greater than or less than 10 years of motor symptoms. Cortical thickness was determined using FreeSurfer, and a bootstrapped linear regression model was used to estimate differences in rates of atrophy between Early and Late patients.

Our results show that patients classified as Early stage exhibit a greater estimated rate of cortical atrophy in left frontal regions, especially the left insula and olfactory sulcus. This pattern was replicated in left‐handed patients, and was not influenced by the degree of motor symptom asymmetry (i.e., left‐sided predominant motor symptoms). Patients classified as Late stage exhibited greater atrophy in the bilateral occipital, and right hemisphere‐predominant cortical areas.

We show that cortical degeneration in PD differs between cerebral hemispheres, and findings suggest a pattern of early left, and late right hemisphere with posterior cortical atrophy. Further investigation is warranted to elucidate the underlying mechanisms of this asymmetry and pathologic implications.