The anterior thalamus is critical for overcoming interference in a context-dependent odor discrimination task.

Abstract

The anterior thalamus (AT) is anatomically interconnected with the hippocampus and other structures known to be involved in memory, and the AT is involved in many of the same learning and memory functions as the hippocampus. For example, like the hippocampus, the AT is involved in spatial cognition and episodic memory. The hippocampus also has a well-documented role in contextual memory processes, but it is not known whether the AT is similarly involved in contextual memory. In the present study, we assessed the role of the AT in contextual memory processes by temporarily inactivating the AT and training rats on a recently developed context-based olfactory list learning task, which was designed to assess the use of contextual information to resolve interference. Rats were trained on one list of odor discrimination problems, followed by training on a second list in either the same context or a different context. In order to induce interference, some of the odors appeared on both lists with their predictive value reversed. Control rats that learned the two lists in different contexts performed significantly better than rats that learned the two lists in the same context. However, AT lesions completely abolished this contextual learning advantage, a result that is very similar to the effects of hippocampal inactivation. These findings demonstrate that the AT, like the hippocampus, is involved in contextual memory and suggest that the hippocampus and AT are part of a functional circuit involved in contextual memory.

Acute modulation of the cholinergic system in the mouse brain detected by pharmacological resting-state functional MRI

“…The cholinergic network is known to be involved in learning and memory and the functional connections that are affected by scopolamine are involved in higher cognitive functions such as spatial memory, episodic memory, contextual memory, attention etc. (Aggleton et al, 2010;Burwell et al, 2004;Fell et al, 2006a,b;Fernandez and Tendolkar, 2006;Law and Smith, 2012;Leech and Sharp, 2014;Lenartowicz and McIntosh, 2005;Marchand et al, 2013;Teixeira et al, 2006). Countless behavior studies in humans and rodents (Hasselmo, 2006;Klinkenberg and Blokland, 2010) show that blockade of cholinergic synaptic transmission leads to disruption of these types of memory functions (Klinkenberg and Blokland, 2010).…”

Functional heterogeneity of the limbic thalamus: From hippocampal to cortical functions

“…Therefore, it is not surprising to observe that memory for temporal order or the use of contextual information to resolve conflicts in an olfactory list learning task are equally impaired by hippocampal and thalamic lesions (Butterly et al, 2012;Fortin et al, 2002;Kesner et al, 2002;Law and Smith, 2012;Wolff et al, 2006). Similarly, concerning the role of the hippocampus in contextual fear conditioning, the latest data available indicate that posttraining hippocampal lesions disrupt the recall of remote but not recent contextual fear memories, in a manner strikingly evocative of the effect of ATN lesions (Dupire et al, 2013;Marchand et al, 2013;Zelikowsky et al, 2012).…”

“…The animals could therefore use the context to resolve interferences. The anterior thalamic lesion prevented the animals to do so, indicating a role for this region in contextual memory (Law and Smith, 2012). Importantly, contextual processing cannot be reduced to pure spatial learning.…”

Mediodorsal but not anterior thalamic nuclei lesions impair acquisition of a conditional discrimination task

“…A recent review of rodent data indicates a major functional dissociation within the limbic thalamus between the anterior (ATN) and mediodorsal (MD) thalamic nuclei, the former supporting essentially hippocampal functions and the latter contributing to prefrontal cortical functions . At the crossroad between direct and indirect hippocampal and midbrain inputs, the ATN are essential to spatial navigation (Jankowski et al, 2013), but recent experimental data (Dupire et al, 2013;Law & Smith, 2012;Marchand, Faugere, Coutureau, & Wolff, 2013;) as well as the study of clinical cases (Carlesimo, Lombardi, & Caltagirone, 2011;Gold & Squire, 2006;Harding, Halliday, Caine, & Kril, 2000;Pergola & Suchan, 2013) indicate that this region may play a broader role in cognition. The MD, on the other hand, entertains privileged links with all divisions of the prefrontal cortex, including the OFC and the mPFC (Groenewegen, 1988).…”