Lesões na parte ventral do núcleo anteromedial do tálamo (AMv) interferem no processamento da memória aversiva predatória sem no entanto influenciar as respostas de defesa inatas do animal frente a um predador. O escopo deste trabalho foi entender melhor o papel do AMv e investigar se seus alvos de projeção corticais também interferem no processamento da memória aversiva. No primeiro experimento detectamos que o AMv participa da aquisição da memória aversiva. As áreas corticais pré-límbica, cingulada anterior, visual anteromedial e retroesplenial ventral, recebem e integram entre si projeções oriundas do AMv, além de enviar projeções para a amígdala e hipocampo. Estas áreas corticais estão seletivamente recrutadas durante a exposição ao predador, e observamos que lesões neuroquímicas afetaram severamente a formação da memória aversiva. Nossos dados sugerem que há um circuito de áreas corticais que está criticamente envolvido no processo mnemônico aqui abordado, e fornece as primeiras evidências para a hipótese de módulos corticais a partir do conectoma do rato. / Neurochemical lesions placed into ventral part of anteromedial thalamic nucleus (AMv) disrupt contextual, but not innate, fear responses to predatory threats. In the present investigation, we determined whether the AMv is involved in the acquisition and/or retrieval of the conditioned responses, and if its cortical targets are involved in the fear memory processing. In the first assay, we found that AMv has a critical role in the acquisition of conditioned responses. The cortical areas prelimbic (PL), anterior cingulate area (ACA), anteromedial visual area (VISam) and the ventral part of retrosplenial area (RSPv), receive projections from AMv and are recruited during predator exposure. The integrity of these cortical areas is required for the processing of the mnemonic processes here addressed. Our data corroborate current ideas on functional cortical modules, and help to elucidate how they are involved in the acquisition of fear memories related to life threatening situations.

Lesões na parte ventral do núcleo anteromedial do tálamo (AMv) interferem no processamento da memória aversiva predatória sem no entanto influenciar as respostas de defesa inatas do animal frente a um predador. O escopo deste trabalho foi entender melhor o papel do AMv e investigar se seus alvos de projeção corticais também interferem no processamento da memória aversiva. No primeiro experimento detectamos que o AMv participa da aquisição da memória aversiva. As áreas corticais pré-límbica, cingulada anterior, visual anteromedial e retroesplenial ventral, recebem e integram entre si projeções oriundas do AMv, além de enviar projeções para a amígdala e hipocampo. Estas áreas corticais estão seletivamente recrutadas durante a exposição ao predador, e observamos que lesões neuroquímicas afetaram severamente a formação da memória aversiva. Nossos dados sugerem que há um circuito de áreas corticais que está criticamente envolvido no processo mnemônico aqui abordado, e fornece as primeiras evidências para a hipótese de módulos corticais a partir do conectoma do rato. / Neurochemical lesions placed into ventral part of anteromedial thalamic nucleus (AMv) disrupt contextual, but not innate, fear responses to predatory threats. In the present investigation, we determined whether the AMv is involved in the acquisition and/or retrieval of the conditioned responses, and if its cortical targets are involved in the fear memory processing. In the first assay, we found that AMv has a critical role in the acquisition of conditioned responses. The cortical areas prelimbic (PL), anterior cingulate area (ACA), anteromedial visual area (VISam) and the ventral part of retrosplenial area (RSPv), receive projections from AMv and are recruited during predator exposure. The integrity of these cortical areas is required for the processing of the mnemonic processes here addressed. Our data corroborate current ideas on functional cortical modules, and help to elucidate how they are involved in the acquisition of fear memories related to life threatening situations.

Repetitive Störungen manifestieren sich als Leitsymptom in der Zwangsstörung und dem Tourette-Syndrom. Die Symptome werden als enthemmte Stereotypien eines desinhibierten Basalganglien-thalamo-kortikalen (BGTC) Regelkreises verstanden. Überdies wird als neurochemisches Korrelat ein dysregulatives Dopamin (DA)-System innerhalb dieser Kerngebiete nahegelegt, welches über ein überaktives Dopamintransporter (DAT)-System erklärt werden könnte. In der Induktion repetitiver Erkrankungen ist die Interaktion des BGTC Regelkreises und des DA-Systems dennoch unklar. In der vorliegenden Arbeit wurden daher anhand von zwei Pathologiemodellen (Ratte) mit unterschiedlich induzierter Dysregulation des DA-Systems (transgen versus pharmakologisch) die dysfunktionalen Einheiten im BGTC Regelkreises vergleichend untersucht. Im transgenen Modell führte die zentralnervöse DAT-Überexpression: (1) zu einer verstärkten Genexpression des vesikulären Monoamintransporter 2 (VMAT2) sowie des DA-Rezeptors 1 und DA–Rezeptors 2 (DRD1, DRD2), (2) zu einem reduzierten DA-Spiegel mit erhöhter DA-Umsatzrate und veränderten serotonergen- und GABAergen-System, und (3) zu perserverativen Verhalten. Im Gegensatz dazu zeigte die chronische Applikation mit dem D2-Agonisten Quinpirol im pharmakologischen Modell: (1) eine Reduktion des DAT, VMAT2 und DRD2, (2) eine reduzierte DA-Umsatzrate und (3) zwanghaftes Kontrollverhalten. Die Ergebnisse legen nahe, dass die unterschiedlichen klinischen Subtypen der Zwangsstörung unterschiedlichen neurobiologischen Veränderungen zugrunde liegen könnten. Ferner bietet das hier vorgestellte transgene Modell erfolgsversprechende Ansatzpunkte um als neues valides Tiermodell der repetitiven Störungen etabliert zu werden. / Repetitive disorders manifest as the cardinal symptom in obsessive-compulsive disorder and Tourette syndrome. The symptoms are understood as disinhibited stereotypies of a basal ganglia-thalamo-cortical (BGTC) circuit. Furthermore, it is suggested that a dysregulated dopamine (DA) system within this circuit is the underlying neurochemical correlate which could be explained by an overactive dopamine transporter (DAT). At this point, it is still unclear how the BGTC circuit and the DA system interact in the induction of repetitive disorders. Therefore we investigated the dysfunctional unities within the BGTC circuit by comparing two pathological rat models (transgenic versus pharmacologic) with different induced dopaminergic dysregulation. The DAT overexpressing rat model showed: (1) increased gene expression of the vesicular monoamine transporter 2 (VMAT2), DA receptor D1 (DRD1) and DA receptor D2 (DRD2), (2) lower levels of DA with an increased DA metabolism and alterations in the serotonin- and GABA system, and (3) perseverative behavior. In contrast, the chronic application of the D2 receptor agonist quinpirole resulted in the pharmacologic model in: (1) lower gene expressions of the DAT, VMAT2 and DRD2, (2) reduced DA-turnover and (3) compulsive control behavior. These results suggest that different clinical subtypes of obsessive-compulsive disorder caused by different neurobiological alterations. In addition, the presented transgenic model provides the opportunity to be established as a new valid animal model of repetitive disorders.