Small fish, large river: Surprisingly minimal genetic structure in a dispersal-limited, habitat specialist fish.

Genetic connectivity is expected to be lower in species with limited dispersal ability and a high degree of habitat specialization (intrinsic factors). Also, gene flow is predicted to be limited by habitat conditions such as physical barriers and geographic distance (extrinsic factors). We investigated the effects of distance, intervening pools, and rapids on gene flow in a species, the Tuxedo Darter (), a habitat specialist that is presumed to be dispersal-limited.

Diversity within the Redeye Bass, Micropterus coosae (Perciformes: Centrarchidae) species group, with descriptions of four new species.

The Redeye Bass, Micropterus coosae, was described from the Mobile River basin, Chattahoochee, and Savannah rivers in Alabama and Georgia, USA, by Hubbs and Bailey (1940). At that time the authors recognized significant variation in the Black Warrior River population, and noted that with further study this form may be recognized as a separate taxon. An examination of variation in morphology and mitochondrial DNA supported this observation, and highlighted additional species-level variation, resulting in descriptions of a total of four new species: Micropterus cahabae, new sp.

Timing of clade divergence and discordant estimates of genetic and morphological diversity in the Slender Madtom, Noturus exilis (Ictaluridae).

Phylogeographic relationships, the timing of clade diversification, and the potential for cryptic diversity in the Slender Madtom, Noturus exilis, was investigated using mitochondrial Cyt b, nuclear RAG2, shape analysis, and meristic and pigmentation data. Three well-supported and deeply divergent clades were recovered from analyses of genetic data: Little Red River (White River drainage) clade, Arkansas+Red River (Mississippi River) clade, and a large clade of populations from the rest of the range of the species. Recovered clades showed little to no diagnostic morphological differences, supporting previous hypotheses of morphological conservatism in catfishes, and indicating morphology may commonly underestimate diversity in this group of fishes.

Sex differences in the correlation of emotional control and amygdala volumes in adolescents.

We examined male and female adolescents (8-18 years of age) that were scanned with structural brain MRI and looked for a correlation between volume of the right or the left amygdala and parent-reported ability of emotional control. A sex difference was found in the correlation between emotional control and the corrected volume of the left amygdala (that is the amygdala volume adjusted for total cranial volume). In girls, smaller left amygdala volumes were associated with better emotional control.

Discordant molecular and morphological evolution in buffalofishes (Actinopterygii: Catostomidae).

Buffalofishes (Genus Ictiobus) are large, robust-bodied suckers adapted to large rivers and lakes of North America. Currently recognized species are readily diagnosed by morphological characters, and the group is known from fossils dating back to the Miocene. However, sympatrically occurring species in the Mississippi River Basin are known to hybridize in nature and in the laboratory.

Abnormal development of the anterior cingulate in childhood-onset schizophrenia: a preliminary quantitative MRI study.

The anterior cingulate is a key component of neural networks subserving attention and emotion regulation, functions often impaired in patients with psychosis. The study aimed to examine anterior cingulate volumes and sulcal morphology in a group of patients with childhood-onset schizophrenia (COS) compared with controls. Brain magnetic resonance imaging (MRI) scans were obtained in 13 COS and 18 matched control children, ages 6-17 years.

Superior temporal gyrus differences in childhood-onset schizophrenia.

The posterior superior temporal gyrus (STG) is the approximate site of Wernicke's area, a language region, which in previous studies has been reported to be abnormal in adults with schizophrenia. The present study assesses volumetric differences in the superior temporal gyrus of subjects with childhood-onset schizophrenia (COS). MRI scans of 18 subjects diagnosed with childhood-onset schizophrenia and 16 age- and sex-matched normals were analyzed to assess possible volume differences.

Gender differences in the left inferior frontal gyrus in normal children.

This study examined frontal lobe subregions in 46 normal children and adolescents (25 females, mean age: 11.08, SD: 3.07; and 21 males, mean age: 10.

Thought disorder and nucleus accumbens in childhood: a structural MRI study.

Thought disorder has been described as a hallmark feature in both adult and childhood-onset schizophrenia. The nucleus accumbens (NAc) has been repeatedly proposed as a critical station for modulating gating of information flow and processing of information within the thalamocortical circuitry. The aim of the present study was to investigate the relationship of thought disorder measures, which were administered to 12 children with schizophrenia and 15 healthy age-matched controls, and NAc volumes obtained from high-resolution volumetric magnetic resonance imaging analyses.

Anterior cingulate, gyrus rectus, and orbitofrontal abnormalities in elderly depressed patients: an MRI-based parcellation of the prefrontal cortex.

Objective: To examine structural abnormalities in subregions of the prefrontal cortex in elderly patients with depression, the authors explored differences in gray matter, white matter, and CSF volumes by applying a parcellation method based on magnetic resonance imaging (MRI).

Method: Twenty-four elderly patients with major depression and 19 group-matched comparison subjects were studied with high-resolution MRI. Cortical surface extraction, tissue segmentation, and cortical parcellation methods were applied to obtain volume measures of gray matter, white matter, and CSF in seven prefrontal subregions: the anterior cingulate, gyrus rectus, orbitofrontal cortex, precentral gyrus, superior frontal cortex, middle frontal cortex, and inferior frontal cortex.

Proton magnetic resonance spectroscopic imaging of the brain in childhood autism.

Background: Autism is a developmental disorder of unknown neurologic basis. Based on prior work, we used proton magnetic resonance spectroscopic imaging ((1)H- MRSI) to investigate brain structures, including cingulate and caudate, that we hypothesized would reveal metabolic abnormalities in subjects with autism.

Methods: In 22 children with autism, 5 to 16 years old, and 20 age-matched healthy control subjects, (1)H-MRSI assessed levels of N-acetyl compounds (NAA), choline compounds (Cho), and creatine plus phosphocreatine (Cr) at 272 msec echo-time and 1.

Cortical sulcal maps in autism.

This study presents the first three-dimensional mapping of cortical sulcal patterns in autism, a pervasive developmental disorder, the underlying neurobiology of which remains unknown. High-resolution T(1)-weighted MRI scans were acquired in 21 autistic (age 10.7 +/- 3.