Seralynne D Vann

..This new evidence for independent functions shows that the mammillary bodies are more than just a hippocampal relay...

..This recall/recognition dissociation provides further evidence for neuroanatomical divisions within recognition memory processes...

..The convergent evidence that mammillary body atrophy impairs recall but spares familiarity-based recognition appears irreconcilable with single-process models...

..This study provides the first clear evidence that the VTNg is critical for memory, and consequently indicates that diencephalic-hippocampal models of memory should be extended to incorporate the limbic midbrain...

..This change in strategy is consistent with anatomical data showing that the dysgranular region is the primary recipient of visual inputs to the rat retrosplenial cortex...

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..At the same time, the remaining mammillary nuclei also contribute to spatial learning, though this may be in a qualitatively different manner...

..These findings show that lesion size is a critical factor and may explain why some studies have failed to find comparable deficits after retrosplenial cortex lesions...

..Future models of spatial and recognition memory will have to extend beyond the hippocampus and perirhinal cortex to incorporate a wider network of cortical and subcortical structures...

..These results provide support for the suggestion that mammillothalamic tract lesions disrupt visuo-spatial encoding...

..Together, these results suggest that mammillary body damage causes an encoding deficit when learning new spatial tasks, resulting in a suboptimal mode of performance, which may reflect a loss of directional heading information...

..From the pattern of impairments it also appears that, with training, rats with lateral mammillary body lesions are able to recruit other navigational systems or that there is some degree of redundancy within the head-direction system...

..This account suggests a role for the mammillary bodies that is independent of their hippocampal inputs...

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..Combining these findings with the results of previous functional and anatomical studies suggests that the granular and dysgranular retrosplenial subregions function in close conjunction to support spatial learning...

..The findings also suggest further functional differences within retrosplenial subregions as area 29 received the large majority of efferents from the subiculum...

..This selective effect of anterior thalamic damage upon retrosplenial activity may both amplify the disruptive effects of anterior thalamic lesions and help to explain the posterior cingulate hypoactivity found in Alzheimer's disease...

..Consequently, the findings suggest that structural learning is heavily dependent on cortico-hippocampal interactions. In contrast, subcortical inputs (such as those from the anterior thalamus) contribute to geometric learning...

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..These results show a subtle impairment in spatial memory performance that is not as severe as that seen when more complete lesions of the retrosplenial cortex are made...

..These limbic projections to the mammillary bodies and anterior thalamus comprise a circuit that is vital for memory, within which the two major components could convey parallel, independent information...

..Such distal effects challenge more traditional views of neuropathology as they reveal how extensive covert pathology might accompany localised overt pathology, and so impair memory...

..The present study not only demonstrates a role for the retrosplenial cortex in allocentric spatial memory, but also explains why previous excitotoxic lesions have failed to detect any deficits...

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..g. nucleus reuniens. These anatomical findings not only reveal novel ways of grouping the neurons within the medial mammillary nucleus, but also indicate that the mammillothalamic connections support cognition in multiple ways...

..Other comparisons revealed underlying similarities with the corresponding projections in the rat brain...

..The overall findings demonstrate the efficacy of this new behavioral task and advance our understanding of object recognition...

..Given how closely imagined experiences match episodic memories, the absence of this function mediated by the hippocampus, may also fundamentally affect the ability to vividly re-experience the past...

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..No other structure was consistently associated with memory. These findings support models of diencephalic memory mechanisms that require hippocampal inputs for recall, but not for key elements of recognition...

..There is, however, growing evidence that when interpreting the effects of retrosplenial lesions, account should be given of the lesion method and its interaction with lesion size...