The ability to represent the world accurately relies on simultaneous coarse and fine-grained neural information coding, capturing both gist and detail of an experience. The longitudinal axis of the hippocampus may provide a gradient of representational granularity in spatial and episodic memory in rodents and humans [1-8]. Rodent place cells in the ventral hippocampus exhibit significantly larger place fields and greater autocorrelation than those in the dorsal hippocampus [1, 9-11], which may underlie a coarser and slower changing representation of space [10, 12]. Recent evidence suggests that properties of cellular dynamics in rodents can be captured with fMRI in humans during spatial navigation [13] and conceptual learning [14]. Similarly, mechanisms supporting granularity along the long axis may also be extrapolated to the scale of fMRI signal. Here, we provide the first evidence for separable scales of representation along the human hippocampal anteroposterior axis during navigation and rest by showing (1) greater similarity among voxel time courses and (2) higher temporal autocorrelation in anterior hippocampus (aHPC), relative to posterior hippocampus (pHPC), the human homologs of ventral and dorsal rodent hippocampus. aHPC voxels exhibited more similar activity at each time point and slower signal change over time than voxels in pHPC, consistent with place field organization in rodents. Importantly, similarity between voxels was related to navigational strategy and episodic memory. These findings provide evidence that the human hippocampus supports an anterior-to-posterior gradient of coarse-to-fine spatiotemporal representations, suggesting the existence of a cross-species mechanism, whereby lower neural similarity supports more complex coding of experience.

We have previously shown that the connectivity of the hippocampus to other regions of the default mode network (DMN) is a strong indicator of memory ability in people with temporal lobe epilepsy (TLE). Recent work in the cognitive neuroscience literature has suggested that the anterior and posterior aspects of the hippocampus have distinct connections to the rest of the DMN and may support different memory operations. Further, structural analysis of epileptogenic hippocampi has found greater atrophy, characterized by mesial temporal sclerosis, in the anterior region of the hippocampus. Here, we used resting state FMRI data to parcellate the hippocampus according to its functional connectivity to the rest of the brain in people with left lateralized TLE (LTLE) and right lateralized TLE (RTLE), and in a group of neurologically healthy controls. We found similar anterior and posterior compartments in all groups. However, there was weaker connectivity of the epileptogenic hippocampus to multiple regions of the DMN. Both TLE groups showed reduced connectivity of the posterior hippocampus to key hubs of the DMN, the posterior cingulate cortex (PCC) and the medial pre-frontal cortex (mPFC). In the LTLE group, the anterior hippocampus also showed reduced connectivity to the DMN, and this effect was influenced by the presence of mesial temporal sclerosis. When we explored brain-behavior relationships, we found that reduced connectivity of the left anterior hippocampus to the DMN hubs related to poorer verbal memory ability in people with LTLE, and reduced connectivity of the right posterior hippocampus to the PCC related to poorer visual memory ability in those with RTLE. These findings may inform models regarding functional distinctions of the hippocampal anteroposterior axis.

Objectives Bipolar disorder (BD) is associated with elevated reward sensitivity and persistent positive affect, yet the neural mechanisms underlying these patterns are not well understood. In the present study, we examined putative disruptions in communication within a well-known corticolimbic reward circuit during reward processing as a potential contributing mechanism to these symptoms. Methods The present investigation employed a within- and between-subjects design utilizing a monetary and social incentive delay task among adults with bipolar disorder type I (BD; N=24) and a healthy non-psychiatric control group (HC; N=25) during fMRI. Participants in the BD group were remitted at the time of testing. Results Functional connectivity analyses revealed increased connectivity between the ventral striatum (VS) seed region and orbitofrontal cortex (OFC) as well as the amygdala during processing of reward receipt in the BD group. After omission of expected rewards, the BD group showed decreased functional connectivity between the ventral striatum and a medial frontopolar cortex (mFPC) region associated with consideration of behavioral alternatives. Follow-up analyses within the BD group showed that increased VS-OFC connectivity after reward receipt, and decreased VS-mFPC connected after reward omission, were associated with higher levels of subthreshold mania symptoms. Conclusions Results point toward potential mechanisms implicated in elevated reward sensitivity in BD. Enhanced VS-OFC connectivity after reward receipt may be involved in elevated valuation of rewards whereas blunted VS-mFPC connectivity after reward omission may reflect a failure to consider behavioral alternatives to reward pursuit.

Cognitive-behavioural therapy (CBT) is an empirically supported treatment for anxiety disorders. CBT treatments are based on disorder-specific protocols that have been developed to target individual anxiety disorders, despite that anxiety disorders frequently co-occur and are comorbid with depression. Given the high rates of diagnostic comorbidity, substantial overlap in dimensional symptom ratings, and extensive evidence that the mood and anxiety disorders share a common set of psychological and biological vulnerabilities, transdiagnostic CBT protocols have recently been developed to treat the commonalities among the mood and anxiety disorders. We conducted a selective review of empirical developments in the transdiagnostic CBT treatment of anxiety and depression (2008)(2009)(2010)(2011)(2012)(2013). Preliminary evidence suggests that theoretically based transdiagnostic CBT approaches lead to large treatment effects on the primary anxiety disorder, considerable reduction of diagnostic comorbidity, and some preliminary effects regarding the impact on the putative, shared psychological mechanisms. However, the empirical literature remains tentative owing to relatively small samples, limited direct comparisons with disorder-specific CBT protocols, and the relative absence of the study of disorder-specific compared with shared mechanisms of action in treatment. We conclude with a treatment conceptualization of the new transdiagnostic interventions as complementary, rather than contradictory, to disorderspecific CBT. W W W L'ensemble croissant des traitements par thérapie cognitivocomportementale pour les troubles anxieux : approches spécifiques par trouble et approches transdiagnostiquesLa thérapie cognitivo-comportementale (TCC) est un traitement soutenu empiriquement pour les troubles anxieux. Les traitements par TCC sont basés sur des protocoles spécifiques par trouble qui ont été élaborés pour cibler les troubles anxieux individuels, malgré qu'il y ait fréquemment cooccurrence et comorbidité des troubles anxieux avec la dépression. Étant donné les taux élevés de comorbidité diagnostique, le chevauchement substantiel des classements dimensionnels des symptômes, et les preuves multiples que les troubles anxieux et de l'humeur partagent un ensemble commun de vulnérabilités psychologiques et biologiques, des protocoles transdiagnostiques de la TCC ont récemment été mis au point pour traiter les éléments communs aux troubles anxieux et de l'humeur. Nous avons mené une revue sélective des développements empiriques du traitement transdiagnostique par TCC de l'anxiété et de la dépression (2008 -2013). Les données probantes préliminaires suggèrent que les approches transdiagnostiques de la TCC basées sur la théorie entraînent d'importants effets de traitement sur le trouble anxieux primaire, une réduction considérable de la comorbidité diagnostique, et certains effets préliminaires en ce qui concerne l'effet sur les mécanismes psychologiques présumés partagés. Toutefois, la littérature empirique demeure provisoire en ra...

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