ABSTRACT
The Eurasian red squirrel (Sciurus vulgaris) is an emblematic species for conservation, and its decline in the British Isles exemplifies the impact that alien introductions can have on native ecosystems. Indeed, red squirrels in this region have declined dramatically over the last 60 years due to the spread of squirrelpox virus following the introduction of the gray squirrel (Sciurus carolinensis). Currently, red squirrel populations in Britain are fragmented and need to be closely monitored in order to assess their viability and the effectiveness of conservation efforts. The situation is even more dramatic in the South of England, where S. vulgaris survives only on islands (Brownsea Island, Furzey Island, and the Isle of Wight). Using the D-loop, we investigated the genetic diversity and putative ancestry of the squirrels from Southern England and compared them to a European dataset composed of 1,016 samples from 54 populations. We found that our three populations were more closely related to other squirrels from the British Isles than squirrels from Europe, showed low genetic diversity, and also harbored several private haplotypes. Our study demonstrates how genetically unique the Southern English populations are in comparison with squirrels from the continental European range. We report the presence of four private haplotypes, suggesting that these populations may potentially harbor distinct genetic lineages. Our results emphasize the importance of preserving these isolated red squirrel populations for the conservation of the species.
ABSTRACT
BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is an approved therapeutic treatment of major depressive disorder and has increasing clinical use throughout the world. However, it remains unclear whether an rTMS course for depression may also produce cognitive enhancement. In a recent meta-analysis of sham-controlled randomized controlled studies (RCTs) conducted in patients with neuropsychiatric conditions, no evidence was found for generalized cognitive enhancing effects across cognitive domains with active compared to sham rTMS. Notwithstanding, there remains the possibility of cognitive effects following an rTMS course that are more highly specific, for example, in specific clinical conditions, or at the individual task level. This study aimed to determine whether a therapeutic rTMS course in patients with depression is associated with cognitive enhancing effects at the task level. METHODS: A systematic review and meta-analysis of outcomes on individual neuropsychological tasks from sham-controlled RCTs where an rTMS course was administered to the dorsolateral prefrontal cortex (DLPFC) in patients with depression. RESULTS: Eighteen studies met the inclusion criteria. Active rTMS treatment showed no specific enhancing effects on the majority of cognitive tasks. Modest effect size improvements with active compared to sham rTMS treatment were found for performance on the Trail Making Test Parts A (g = 0.28, 95% CI = 0.06-0.50) and B (g = 0.26, 95% CI = 0.06-0.47). CONCLUSION: A therapeutic rTMS course administered to the prefrontal cortex for depression may produce modest cognitive enhancing effects specific to psychomotor speed, visual scanning, and set-shifting ability.
Subject(s)
Cognition/physiology , Depressive Disorder, Major/physiopathology , Depressive Disorder, Major/therapy , Prefrontal Cortex/physiology , Transcranial Magnetic Stimulation , Depression , Depressive Disorder, Major/psychology , Female , Humans , Male , Randomized Controlled Trials as Topic , Research Design , Treatment OutcomeABSTRACT
Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a therapeutic intervention for neuropsychiatric illnesses and has demonstrated efficacy for treatment of major depression. However, an unresolved question is whether a course of rTMS treatment results in effects on cognitive functioning. In this systematic review and meta-analysis we aimed to quantitatively determine whether a course of rTMS has cognitive enhancing effects. We examined cognitive outcomes from randomised, sham-controlled studies conducted in patients with neuropsychiatric conditions where rTMS was administered to the dorsolateral prefrontal cortex (DLPFC) across repeated sessions, searched from PubMed/MEDLINE and other databases up until October 2015. Thirty studies met our inclusion criteria. Cognitive outcomes were pooled and examined across the following domains: Global cognitive function, executive function, attention, working memory, processing speed, visual memory, verbal memory and visuospatial ability. Active rTMS treatment was unassociated with generalised gains across the majority of domains of cognitive functioning examined. Secondary analyses revealed a moderate sized positive effect for improved working memory in a small number of studies in patients with schizophrenia (k = 3, g = 0.507, 95 % CI = [0.183-0.831], p < .01). Therapeutic rTMS when administered to the DLPFC in patients with neuropsychiatric conditions does not result in robust cognitive enhancing effects.
