Projections from the anterodorsal and anteroveniral nucleus of the thalamus to the limbic cortex in the rat

Abstract

The present study characterized the projections of the anterodorsal (AD) and the anteroventral (AV) thalamic nuclei to the limbic cortex. Both AD and AV project to the full extent of the retrosplenial granular cortex in a topographic pattern. Neurons in caudal parts of both nuclei project to rostral retrosplenial cortex, and neurons in rostral parts of both nuclei project to caudal retrosplenial cortex. Within AV, the magnocellular neurons project primarily to the retrosplenial granular a cortex, whereas the parvicellular neurons project mainly to the retrosplenial granular b cortex. AD projections to retrosplenial cortex terminate in very different patterns than do AV projections: The AD projection terminates with equal density in layers I, III, and IV of the retrosplenial granular cortex, whereas, in contrast, the AV projections terminate very densely in layer Ia and less densely in layer IV. Further, both AD and AV project densely to the postsubicular, presubicular, and parasubicular cortices and lightly to the entorhinal (only the most caudal part) cortex and to the subiculum proper (only the most septal part). Rostral parts of AD project equally to all three subicular cortices, whereas neurons in caudal AD project primarily to the postsubicular cortex. Compared to AD, neurons in AV have a less extensive projection to the subicular cortex, and this projection terminates primarily in the postsubicular and presubicular cortices. Further, the AD projection terminates in layers I, II/III, and V of postsubiculum, whereas the AV projection terminates only in layers I and V.

Beyond Spatial Memory: The Anterior Thalamus and Memory for the Temporal Order of a Sequence of Odor Cues

“…It is possible that mPFC lesions affect memory for temporal order regardless of the number of items and interitem delay, whereas hippocampal and AT lesions only affect temporal separation for numerous, closely linked items. Although the apparently similar deficits on memory for temporal order observed after both AT and hippocampal lesions may be attributable to their strong connections via the fornix, mamillary bodies, retrosplenial cortex, and subicular regions (Wyss and Van Groen, 1992;Shibata, 1993;Van Groen and Wyss, 1995;Shibata, 1998;van Groen et al, 1999), interconnections also exist between the AT nuclei and the mPFC (van Groen et al, 1999;Shibata and Naito, 2005), so the AT lesion effect on memory for temporal order in the current study may reflect both AT-hippocampal and AT-mPFC interactions. Future work on the effects of crossed unilateral hippocampal, mPFC, and AT lesions on memory for temporal order using the procedures used in the current study may help answer this question.…”

Coexpression of vesicular glutamate transporters 1 and 2, glutamic acid decarboxylase and calretinin in rat entorhinal cortex

“…Several of these nuclei host neurons that express CR (Résibois and Rogers 1992). A major thalamic input arrives from the nucleus reuniens of the thalamus (NRT; Beckstead 1978, Wouterlood et al 1990Vertes et al 2006) whereas additional diencephalic input is supplied by the paratenial, periventricular and anteromedial thalamic nuclei (Beckstead 1978;van Groen et al 1995) and the ventromedial hypothalamic nucleus (Canteras et al 1994). Several of these nuclei contain CR neurons (Résibois and Rogers 1992;Arai 1994).…”

Decoding signal processing in thalamo-hippocampal circuitry: implications for theories of memory and spatial processing

“…The pathways mediating these signals share similar connectivity, arising from Gudden's tegmental nuclei-mammillary bodies-anterior thalamic nuclei-retrosplenial/entorhinal cortices-hippocampal formation (the latter including the hippocampus and the subicular cortices ( Fig. 1) (Gonzalo-Ruiz et al, 1997;Shibata, 1993;Swanson and Cowan, 1977; Van Groen and Wyss, 1995;van Groen et al, 1999;Witter et al, 1990). The anatomical substrates of these parallel pathways at a thalamic level involves the anterodorsal and anteroventral nuclei, respectively.…”

“…The Papez's pathways mediating theta rhythm share remarkably similar connectivity to those mediating head-direction signals. Both pathways involve the tegmental nuclei, mammillary bodies, anterior thalamic nuclei and subicular cortices (Gonzalo-Ruiz et al, 1997;Shibata, 1993;Swanson and Cowan, 1977;Van Groen and Wyss, 1995;van Groen et al, 1999;Witter et al, 1990). Thalamo-hippocampal circuitry involved in theta rhythm is represented by the anterovetral thalamic nucleus and subiculum together with medial entorhinal cortex.…”