To investigate connectivity between primary somatosensory area (S1) and striate cortex (V1) in the blind, we used dynamic causal modeling of functional MRI acquired while 15 blind (9 early-onset and 6 late-onset) and 24 sighted subjects performed a tactile Braille discrimination task with their right hand. Five regions of interest were selected from either the ventral or dorsal pathways: left S1, anterior intraparietal sulcus (aIPS), superior occipital gyrus (SOG), inferior occipital gyrus (IOG), and V1. Bayesian model comparison showed that a cortico-cortical feedback pathway model without direct connections between V1 and S1 performed better than that with direct connections. In the blind, baseline connectivity and its discrimination-specific modulation in aIPS-SOG and aIPS-IOG were positive and bi-directional, while they were negative in the sighted. Thus visual deprivation may induce reorganization of the visual cortical areas due to the competitive shift for tactile inputs. The early blind showed stronger connectivity than the late blind in the dorsal pathway (aIPS-V1 through SOG) and in SOG-IOG bi-directionally. Task performance positively correlated with baseline connectivity of SOG-V1 and SOG-IOG across blind subjects. Therefore, dorsal visual regions are involved in the functional shift in V1 from visual to tactile information processing in blind subjects.

A single dose of DCS or VPA might enhance exposure-based cognitive therapy of anxiety disorders by reducing the vulnerability to reinstatement and preventing relapses of fear-conditioned responses.

Although patients with major depressive disorder typically have a reduced hippocampal volume, particularly in the cornu ammonis 1 (CA1), animal studies suggest that depressive mood is related to the dentate gyrus (DG). In this study, our objective was to clarify which hippocampal subregions are functionally associated with depressive mood in humans. We conducted a functional MRI (fMRI) study on 27 cognitively intact volunteers. Subjects performed a modified version of a delayed matching-to-sample task in an MRI scanner to investigate pattern separation-related activity during each phase of encoding, delay, and retrieval. In each trial, subjects learned a pair of sample cues. Functional MR images were acquired at a high spatial resolution, focusing on the hippocampus. Subjects also completed the Beck Depression Inventory (BDI), a questionnaire about depressive mood. Depending on the similarity between sample cues, activity in the DG/CA3 and medial CA1 in the anterior hippocampus changed only during encoding. Furthermore, the DG/CA3 region was more active during successful encoding trials compared to false trials. Activity in the DG/CA3 and lateral CA1 was negatively correlated with BDI scores. These results suggest that the DG/CA3 is the core region for pattern separation during the encoding phase and interacts with the medial CA1, depending on the similarity of the stimuli, to achieve effective encoding. Impaired activity in the DG/CA3, as well as in the lateral CA1, was found to be associated with depressive symptoms, even at a subclinical level.