Does stress damage the brain?

Studies in animals showed that stress results in damage to the hippocampus, a brain area involved in learning and memory, with associated memory deficits. The mechanism involves glucocorticoids and possibly serotonin acting through excitatory amino acids to mediate hippocampal atrophy. Patients with posttraumatic stress disorder (PTSD) from Vietnam combat and childhood abuse had deficits on neuropsychological measures that have been validated as probes of hippocampal function. In addition, magnetic resonance imaging (MRI) showed reduction in volume of the hippocampus in both combat veterans and victims of childhood abuse. In combat veterans, hippocampal volume reduction was correlated with deficits in verbal memory on neuropsychological testing. These studies introduce the possibility that experiences in the form of traumatic stressors can have long-term effects on the structure and function of the brain.     

Does personality change as a result of fetal tissue transplantation in the brain?

This study examined the effects on personality of transplantation of fetal tissue into the brains of participants in a double-blind placebo control trial for the treatment of Parkinson's disease (PD). Thirty persons with PD (equal numbers of males and females) participated in a larger study investigating the efficacy of transplantation of fetal neural tissue versus placebo surgery. Participants were randomly assigned to receive either the fetal transplant or placebo surgery. The blind was lifted for all patients approximately 13 months after surgery, at which time individuals who had received the placebo surgery could choose to receive the transplant surgery. In this study 12 persons originally received the transplant and 18 received placebo surgery. The NEO Five-Factor Inventory (NEO-FFI), a commonly used measure of personality characteristics, was administered to participants at baseline, 12, and 24 months after surgery. Scores at baseline for the Openness and Agreeableness scales were significantly higher for this sample of PD patients than scores for the normative group. There were no changes on any of the five scales from baseline to 12 months for the total group. The only significant change in the original transplant group was a decrease in Conscientiousness from baseline to 24 months. There were no changes over time among the group who had placebo surgery first and then the transplant. Results indicate that personality, as measured by the NEO-FFI, basically remained stable during the two-year follow-up period of this study. In this case, no change is regarded as a positive outcome.     

Does the brain make waves to improve stability?

In many ways, roboticians and the human brain are faced with the same problem: How does one control movement from a distance? In both cases, delays in the transmission of information play an important role, either because the distances to be covered are long (imagine controlling a robot arm on the moon from a command center on Earth), or because the underlying hardware is slow (nerves transmit information much more slowly than wires, radio waves or light). Delays have a debilitating effect on feedback control systems; causes and effects can bounce back and forth between distant sites, resulting in oscillatory behavior that can grow without bound. Control engineers have developed the concept of wave variables to combat this problem—by mimicking a flexible rod, wave variables constrain movement of the master and slave during the delay, ensuring stable overall behavior [G. Niemeyer, J.J.E. Slotine, Stable adaptive teleoperation, IEEE J. Ocean Eng. 16 (1991) 152–162; G. Niemeyer, J.J.E. Slotine, Toward bilateral internet teleoperation, in: Beyond Webcams, an Introduction to Online Robots, MIT Press, 2002]. Mother Nature may, however, deserve the patent on this solution. As we show here, the properties of nerves, muscles and sensory organs combine to form a natural wave variable control system that is immune to the problems of feedback delays.     

Does the brain oscillate? The dispute on neuronal synchronization

Astract. The present essay concisely analyses the contemporary neurobiological debate concerning the hypothesis of the temporal correlation advanced to solve the perceptual problem of linking different features in a unitary object or visual scene. Although fascinating and grounded on simulations and brain models, in addition to important electrophysiological findings on the sensory systems, this hypothesis is regarded as not conclusive, and it still excites numerous critical observations from different approaches. Nevertheless, it has contributed to an innovative use of the idea of cortical oscillations, as regards its usual employment in reference to the electrical activity of the brain. It also opens a new perspective in the assumption of the temporal pattern to read the neural code.     

Does sleep restore the topology of functional brain networks?

Previous studies have shown that healthy anatomical as well as functional brain networks have small‐world properties and become less optimal with brain disease. During sleep, the functional brain network becomes more small‐world‐like. Here we test the hypothesis that the functional brain network during wakefulness becomes less optimal after sleep deprivation (SD). Electroencephalography (EEG) was recorded five times a day after a night of SD and after a night of normal sleep in eight young healthy subjects, both during eyes‐closed and eyes‐open resting state. Overall synchronization was determined with the synchronization likelihood (SL) and the phase lag index (PLI). From these coupling strength matrices the normalized clustering coefficient C (a measurement of local clustering) and path length L (a measurement of global integration) were computed. Both measures were normalized by dividing them by their corresponding C‐s and L‐s values of random control networks. SD reduced alpha band C/C‐s and L/L‐s and theta band C/C‐s during eyes‐closed resting state. In contrast, SD increased gamma‐band C/C‐s and L/L‐s during eyes‐open resting state. Functional relevance of these changes in network properties was suggested by their association with sleep deprivation‐induced performance deficits on a sustained attention simple reaction time task. The findings indicate that SD results in a more random network of alpha‐coupling and a more ordered network of gamma‐coupling. The present study shows that SD induces frequency‐specific changes in the functional network topology of the brain, supporting the idea that sleep plays a role in the maintenance of an optimal functional network. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.     

Does a "moderate" alcohol intake damage the brain?

A range of volumetric and neurochemical analyses were carried out on the brains of 14 "moderate" drinkers. These data were compared with previous studies from controls and alcoholics. Volumetric measurements consistently suggest a loss of cerebral tissue although the differences were not statistically significant. Changes in the lipid and water content of the white matter were noted and the significance of these changes in relation to the pathogenesis of reversible brain shrinkage caused by alcohol abuse is discussed.     

Narcissists’ social pain seen only in the brain

Narcissism is a complex phenomenon, involving a level of defensive self-enhancement. Narcissists have avoidant attachment styles, maintain distance in relationships and claim not to need others. However, they are especially sensitive to others’ evaluations, needing positive reflected appraisals to maintain their inflated self-views, and showing extreme responses (e.g. aggression) when rejected. The current study tested the hypothesis that narcissists also show hypersensitivity in brain systems associated with distress during exclusion. We measured individual differences in narcissism (Narcissistic Personality Inventory) and monitored neural responses to social exclusion (Cyberball). Narcissism was significantly associated with activity in an a priori anatomically defined social pain network (anterior insula, dorsal anterior cingulate cortex and subgenual anterior cingulate cortex) during social exclusion. Results suggest hypersensitivity to exclusion in narcissists may be a function of hypersensitivity in brain systems associated with distress, and suggests a potential pathway that connects narcissism to negative consequences for longer-term physical and mental health—findings not apparent with self-report alone.     

Does the neurologist contribute to the care of patients with chronic back pain?

OBJECTIVE: To review the disposition and outcome of patients with back pain seen in a neurology clinic, and determine the value of the neurologist's input. BACKGROUND: Back pain is a common cause of referral to the neurology clinic, but it is not clear how much the neurologist contributes to the care of such patients. DESIGN/METHODS: We reviewed all new patients and new consultations seen for the following reasons: low back pain; 'sciatica'; 'back and leg pain', and 'spinal stenosis'. Patients were evaluated by a single attending neurologist at a general neurology clinic over a 2-year period (January 1997 through December 1998). RESULTS: During the 2-year period, there were 97 patients seen for the above reasons. The chief complaint was low back pain alone in 73, while it was combined with another symptom in 24 (leg pain in 18, buttock or hip pain in 6). Thirty-three patients were self-referred, 56 were referred by a healthcare professional, 3 were referred by attorneys, and the referral source was unclear in 5. Median age was (range 25-90) years. Forty-eight were males. Based on the clinical data (history and examination), clinical diagnoses were radiculopathy in 28, myelopathy in 2, uncomplicated spondylosis in 27, and other non-neurologic conditions in 45. Tests performed after the visit included X-rays in 31, CT in 1, MRI in 16, and EMG in 17. 'Final' diagnoses were radiculopathy in 29 patients, myelopathy in 2 (total neurologic n = 30), uncomplicated spondylosis in 27, and other non-neurologic diagnoses in 41 (total non-neurologic n = 67). The non-neurologic diagnoses included periarticular pain, bursitis, muscle strain, soft tissue injury, and vertebral compression fractures. Final dispositions in the non-neurologic group (n = 67) were: nonsteroidal anti-inflammatories (NSAIDs) in 34 patients; analgesics or muscle relaxants in 37; physical therapy for 19, and none (including rest and observation) for 22. Four patients were referred for epidural blocks. (Many patients had more than one final disposition.) Final dispositions in the neurologic group (n = 39) were: physical therapy (n = 9); NSAIDs (n = 12); analgesics or muscle relaxants (n = 12), and epidural blocks (n = 3). Three patients were referred for surgery, but only 1 had an operation. CONCLUSIONS: Of patients with back pain and related symptoms seen in a neurology clinic, about two thirds have non-neurologic conditions. These patients are usually treated symptomatically with medications, rest, and physical therapy, all of which could be managed by primary care physicians. In the neurologic group, the vast majority is treated in the same way as the non-neurologic group. When more specific measures are needed, such as surgery or pain management procedures (e.g., epidural blocks), then the patients could be evaluated directly by the proper specialist (pain management or spine surgery) rather than the neurologist. The neurologist's input does not significantly affect the diagnosis or the management, so that the neurologist appears to have no useful role in the management of such patients.