Under the influence of light: How light pollution disrupts personality and metabolism in hermit crabs.

Anthropogenic disturbances are known to cause significant physiological and behavioural changes in animals and, thus, are the critical focus of numerous studies. Light pollution is an increasingly recognised source of disturbance that has the potential to impact animal physiology and behaviour. Here, we investigate the effect of constant light on a personality trait and metabolic rate in the European hermit crab Pagurus bernhardus. We used Bayesian mixed models to estimate average behavioural change (i.e. sample mean level behavioural plasticity) and between- and within-individual variation in boldness in response to laboratory light. Hermit crabs experiencing constant light were consistently less bold and had a higher metabolic rate than those kept under a standard laboratory light regime (12:12 h light/dark). However, there was no effect of light on individual consistency in behaviour. As boldness is associated with coping with risk, hermit crabs exposed to light pollution at night may experience increased perceived predation risk, adjusting their behaviour to compensate for the increased conspicuousness. However, reduced boldness could lead to lower rates of foraging and this, in combination with elevated metabolic rate, has the potential for a reduction in energy balance.

Transcranial magnetic stimulation, deep brain stimulation and personal identity: ethical questions, and neuroethical approaches for medical practice.

Neurotechnology provides means to engage micro- and macrostructural networks of the brain to both mitigate the manifestations of several neurological and psychiatric disorders, and alter cognition and motoric activity. Such capacity also generates questions of how these interventions may affect personal identity. This paper discusses the ethical implications regarding changes to personal identity that arise from the therapeutic use of transcranial magnetic stimulation (TMS) and deep brain stimulation (DBS) technologies. In addition, we raise the question of whether changes in personal identity, as a side effect of these interventions, are ethically acceptable and whether such alterations of personality foster patients' sense of well-being and autonomy. First, we provide a series of case vignettes that afford an overview of the ways that various neurological interventions can affect personal identity. Second, we offer a brief working definition of personal identity in order to delineate an ethical framework that we deem necessary for the responsible use of neurostimulation technologies. In so doing, we argue that neurostimulation therapy, as a doctoring act, should be directed, and adherent to goals of restoring and/or preserving patients' personal identity. To this end, we offer an ethical framework that we believe enables sound decisions about the right and good use of TMS and DBS.

Deep brain stimulation, personal identity and policy.

A range of implantable brain-interfacing devices (IBIDs) is currently in use and development for the treatment of movement disorders and disorders of mood, behaviour and thought. These include cochlear implants, deep brain stimulation (DBS), prosthetic limbs, and optogenetic interventions (the combined use of genetics and optics to control individual cells). While implantable non-brain devices, such as implantable cardioverter defibrillators, began receiving US Food and Drug Administration approval in 1980, the development of IBIDs is recent, with the approval of DBS for Parkinson's disease in 1997. The expansion in use of IBIDs from neurological to psychiatric conditions is even more recent, with current trials underway for a range of disorders including depression, OCD, addiction, Alzheimer's disease and Tourette's syndrome. Emerging applications of existing IBIDs and new devices in development differ from currently approved devices and applications in two potentially crucial ways: 1) They target conditions traditionally seen as psychiatric; and/or 2) They target and modify functions or traits tied closely to agency, personal identity and personhood. As such, understanding patients' and caregivers' conceptions of personal identity in the context of disease and treatment is important not only for the informed consent process, but also for questions of public policy.

Electroencephalographic, personality, and executive function measures associated with frequent mobile phone use.

The present study employs standardized data acquired from the Brain Resource International Database to study the relationship between mobile phone usage, personality, and brain function (n = 300). Based on the frequency and duration of mobile phone usage, three groups were formed. The findings suggest a subtle slowing of brain activity related to mobile phone use that is not explained by differences in personality. These changes are still within normal physiological ranges. Better executive function in mobile phone users may reflect more focused attention, possibly associated with a cognitive training effect (i.e., frequently making phone calls in distracting places), rather than a direct effect of mobile phone use on cognition.

Chronic deep brain stimulation of the subthalamic nucleus for Parkinson's disease: effects on cognition, mood, anxiety and personality traits.

OBJECTIVE: To evaluate modifications occurring in cognitive functions and behavioural aspects in a group of 72 consecutive patients with Parkinson's disease (PD) 15 months after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN). METHODS: 72 consecutive PD patients bilaterally implanted for DBS of the STN were evaluated before and after surgery with a mean follow-up of 15 months. A neuropsychological assessment was performed to evaluate reasoning (Raven Colour Matrices), memory (Bisyllabic Word Repetition Test, Corsi's Block-Tapping Test, Paired-Associate Learning) and frontal executive functions (Trail Making Test Part B, Nelson Modified Card Sorting Test, phonemic and category verbal fluency tasks). Mood and suicidal ideation were evaluated using the Beck Depression Inventory (BDI). Anxiety was measured by means of the State-Trait Anxiety Inventory and personality traits were evaluated with the Structured Clinical Interview for the DSM-III-R Axis II Disorders (SCID-II). Assessment of thought disorders and apathy was based on subitems of the Unified Parkinson's Disease Rating Scale. RESULTS: The comparisons between pre- and postoperative neuropsychological test scores showed a significant worsening only in phonemic and semantic verbal fluency tasks, while fewer errors were found in the Nelson Modified Card Sorting Test. Globally, behavioural assessment evidenced a small improvement in mood, as assessed by the BDI, in obsessive-compulsive and paranoid personality traits (SCID-II). Thought disorders worsened while suicidal ideation, anxiety and apathy showed no postoperative modifications. The analysis of individual outcomes (+/-1 SD criterion) evidenced a relevant postoperative cognitive decline in 3 patients out of 65 (4.5%). Moreover, following implantation, 1 patients exhibited psychosis (1.5%), 2 patients experienced a clinically relevant worsening of depressive symptoms (3%), 7 patients showed an increase in anxiety (12%) and 3 patients a worsening in depression and anxiety symptoms (3%). On the contrary, 12 patients (20%) showed a relevant improvement in mood and 14 patients (23%) a relevant reduction of anxiety symptoms after the surgery. CONCLUSIONS: The present study confirms that STN DBS is cognitively safe since the only relevant change observed was a mild decrease in verbal fluency tasks. Globally, a small postoperative improvement was found in the BDI, and in two SCID-II subscales concerning obsessive-compulsive and paranoid personality traits, even though postoperative behavioural disturbances can occur in individual patients.

Neurobehavioral sequelae of cranial irradiation in adults: a review of radiation-induced encephalopathy.

PURPOSE: To examine behavioral dimensions of treatment outcomes for patients receiving cranial irradiation. Radiation encephalopathy is one of these and refers to significant cognitive and emotional dysfunction following radiation therapy to the brain. Issues of definition, estimated incidence, pathophysiologic mechanisms, and recommended research designs are reviewed in relationship to functional neurobehavioral outcomes. PATIENTS AND METHODS: Twenty-nine studies of adults receiving therapeutic cranial irradiation (TCI) involving 748 patients and 18 studies of prophylactic cranial irradiation (PCI) involving 368 patients are reviewed. Assessment of patient outcomes are summarized for research published since 1980, with specific attention to adverse changes in cognitive and emotional functioning. RESULTS: Analyses revealed that 213 TCI patients and 100 PCI patients showed encephalopathy attributed to radiation. Manifestations of the late delayed effects of radiotherapy on brain function are related to patient age, total dose of irradiation, fraction sizes, and timing of chemotherapy. Radiation encephalopathy appears to be more common than the pathologic tissue injury of radiation necrosis. Accurate diagnosis of these neurobehavioral sequelae can require follow-up over a period of years with sensitive assessment procedures. CONCLUSIONS: It is likely that the true incidence of treatment-related side effects of cranial irradiation in adults who survive more than 6 months without brain tumor growth or recurrence has been significantly underestimated. Research designs that include formal neuropsychologic assessment in conjunction with other neurodiagnostic tests can provide more comprehensive evaluation of long-term neurobehavioral outcomes.