The role of the dentate gyrus in the formation of contextual representations

The hippocampus is involved in encoding and integrating contextual information. Recently, it has been suggested that the dorsal dentate gyrus (dDG) hippocampal subregion may mediate the formation of contextual representations of the spatial environment through a conjunctive encoding process whereby incoming multimodal information is integrated into a single higher‐order representation. Despite anatomical evidence in support of this claim, behavioral evidence is limited. Therefore, a contextual associative learning paradigm was used to determine whether the dDG supports the formation of integrated contextual representations. Male Long‐Evans rats were randomly assigned as controls or to receive bilateral intracranial infusions of colchicine into the dDG. Following recovery from surgery, each rat was tested on an appetitive task that required animals to form an association between a cue (odor) and a context to receive a food reward. Each rat received 10 trials per day and was tested for 10 consecutive days. Upon completion of testing, animals were tested on an additional two‐choice olfactory and contextual discrimination task. The testing order was counterbalanced across animals. Results showed that control animals successfully acquired the contextual associative learning task for olfactory stimuli as indicated by improved performance across the 10 testing days. In contrast, animals with dDG lesions were impaired in the ability to acquire the odor‐context associations. Results from follow‐up odor and context discrimination tests indicated that both groups acquired the discriminations at similar rates. Therefore, it is unlikely that deficits in performance on the contextual associative learning task were due to an inability to discriminate between odors or contexts. The present findings provide further support for DG involvement in the formation of conjunctive contextual representations. © 2012 Wiley Periodicals, Inc.     

A Randomized Experimental Test of the Efficacy of EMDR Treatment on Negative Body Image in Eating Disorder Inpatients

Eye Movement Desensitization and Reprocessing (EMDR) therapy is being used by some clinicians to treat eating disorders. Although there is anecdotal and case study data supporting its use, there are no controlled studies examining its effectiveness with this population. This study examined the short and long-term effects of EMDR in a residential eating disorders population. A randomized, experimental design compared 43 women receiving standard residential eating disorders treatment (SRT) to 43 women receiving SRT and EMDR therapy (SRT+EMDR) on measures of negative body image and other clinical outcomes. SRT+EMDR reported less distress about negative body image memories and lower body dissatisfaction at posttreatment, 3-month, and 12-month follow-up, compared to SRT. Additional comparisons revealed no differences between the conditions pre to posttreatment on other measures of body image and clinical outcomes. The empirical evidence reported here suggests that EMDR may be used to treat specific aspects of negative body image in conjunction with SRT, but further research is necessary to determine whether or not EMDR is effective for treating the variety of eating pathology presented by eating disorder inpatients.     

Cerebral Blood Flow Abnormalities in Children With Sickle Cell Disease: A Systematic Review

A systematic review was performed to assess whether cerebral blood flow with different imaging modalities could identify brain abnormalities in children with sickle cell disease where structural magnetic resonance imaging and transcranial Doppler velocity appeared normal. A total of 11 studies were identified which reported cerebral blood flow abnormalities alongside structural magnetic resonance imaging or transcranial Doppler velocity abnormalities in patients with sickle cell disease. Potential for bias was assessed with the quality assessment of diagnostic accuracy studies scale in addition to treatment bias. Subjects of each study were categorized into patients with and without stroke. The prevalence of abnormalities for each modality was then separately calculated in each group. The included studies had mostly moderate degrees of bias. The prevalence of blood flow abnormalities compared with structural magnetic resonance imaging abnormalities was equal to or lower in patients with stroke and equal to or greater in patients without stroke. Blood flow abnormalities were more prevalent than transcranial Doppler abnormalities in four studies of patients without stroke and in one study of patients with stroke. The studies suggest that the assessment of cerebral blood flow in sickle cell disease can be of potential value in addressing brain abnormalities at the tissue level; however, further studies are warranted.     

Disease-Specific Quality of Life in Young Patients With Tourette Syndrome

Tourette syndrome is a neurodevelopmental disorder characterized by multiple tics and is often associated with comorbid behavioral problems. Research with generic instruments in child populations showed that comorbid disorders can have a greater impact on health-related quality of life than tic severity. This study investigated the usefulness of a newly developed disease-specific instrument, the Gilles de la Tourette Syndrome–Quality of Life Scale for Children and Adolescents (GTS-QOL-C&A), in assessing health-related quality of life in young patients with Tourette syndrome with and without behavioral comorbidity. We recruited 75 patients with Tourette syndrome (60 males; age 12.4 ± 3.2 years). All participants were evaluated by a neuropsychiatrist and completed a standardized psychometric battery, including the GTS-QOL-C&A, Child Depression Inventory, and Multidimensional Anxiety Scale for Children. Forty-two patients (56%) fulfilled diagnostic criteria for at least one comorbidity: obsessive-compulsive disorder (n = 25 patients [33.3%]); attention deficit/hyperactivity disorder (n = 6 patients [8%]); both (n = 11 patients [14.7%]). The GTS-QOL-C&A demonstrated usefulness in differentiating “pure” Tourette syndrome from Tourette syndrome “plus” behavioral problems with regard to health-related quality of life scores for the obsessive-compulsive subscale. In addition to focusing on core tic symptoms, the GTS-QOL-C&A showed sensitivity to the impact of behavioral comorbidities on health-related quality of life and can usefully complement existing nonspecific instruments.     

Nonverbal imitation skills in children with specific language delay

Research in children with language problems has focussed on verbal deficits, and we have less understanding of children's deficits with nonverbal sociocognitive skills which have been proposed to be important for language acquisition. This study was designed to investigate elicited nonverbal imitation in children with specific language delay (SLD). It is argued that difficulties in nonverbal imitation, which do not involve the processing of structural aspects of language, may be indicative of sociocognitive deficits. Participants were German-speaking typically developing children (n = 60) and children with SLD (n = 45) aged 2–3½ years. A novel battery of tasks measured their ability to imitate a range of nonverbal target acts that to a greater or lesser extent involve sociocognitive skills (body movements, instrumental acts on objects, pretend acts). Significant group differences were found for all body movement and pretend act tasks, but not for the instrumental act tasks. The poorer imitative performance of the SLD sample was not explained by motor or nonverbal cognitive skills. Thus, it appeared that the nature of the task affected children's imitation performance. It is argued that the ability to establish a sense of connectedness with the demonstrator was at the core of children's imitation difficulty in the SLD sample.     

Regulation of glutamate release by heteromeric nicotinic receptors in layer V of the secondary motor region (Fr2) in the dorsomedial shoulder of prefrontal cortex in mouse

We studied how nicotinic acetylcholine receptors (nAChRs) regulate glutamate release in the secondary motor area (Fr2) of the dorsomedial murine prefrontal cortex, in the presence of steady agonist levels. Fr2 mediates response to behavioral situations that require immediate attention and is a candidate for generating seizures in the frontal epilepsies caused by mutant nAChRs. Morphological analysis showed a peculiar chemoarchitecture and laminar distribution of pyramidal cells and interneurons. Tonic application of 5 µM nicotine on Layer V pyramidal neurons strongly increased the frequency of spontaneous glutamatergic excitatory postsynaptic currents. The effect was inhibited by 1 µM dihydro‐β‐erythroidine (which blocks α4‐containing nAChRs) but not by 10 nM methyllicaconitine (which blocks α7‐containing receptors). Excitatory postsynaptic currents s were also stimulated by 5‐iodo‐3‐[2(S)‐azetidinylmethoxy]pyridine, selective for β2‐containing receptors, in a dihydro‐β‐erythroidine ‐sensitive way. We next studied the association of α4 with different populations of glutamatergic terminals, by using as markers the vesicular glutamate transporter type (VGLUT) 1 for corticocortical synapses and VGLUT2 for thalamocortical projecting fibers. Immunoblots showed higher expression of α4 in Fr2, as compared with the somatosensory cortex. Immunofluorescence showed intense VGLUT1 staining throughout the cortical layers, whereas VGLUT2 immunoreactivity displayed a more distinct laminar distribution. In Layer V, colocalization of α4 nAChR subunit with both VGLUT1 and VGLUT2 was considerably stronger in Fr2 than in somatosensory cortex. Thus, in Fr2, α4β2 nAChRs are expressed in both intrinsic and extrinsic glutamatergic terminals and give a major contribution to control glutamate release in Layer V, in the presence of tonic agonist levels. Synapse 00:000–000, 2013 . © 2013 Wiley Periodicals, Inc.     

Selected topics of the DGPPN Congress 2012

European Archives of Psychiatry and Clinical Neuroscience -