Deficits in prospective memory following damage to the medial subdivision of the mediodorsal thalamic nucleus

Abstract

Identifying the neurocognitive mechanisms that lead individuals remembering to execute an intention at the right moment (prospective memory, PM) and how such mechanisms are influenced by the features of that intention is a fundamental theoretical challenge. In particular, the functional contribution of subcortical regions to PM is still unknown. This study was aimed at investigating the role of the medial subdivision of the mediodorsal thalamic nucleus (mMDT) in PM, with particular focus on the processes that are mediated by the projections from/to this structure. We analysed the performance of a patient (OG) with a right-sided lesion involving the mMDT in a series of PM tasks that varied for focality (i.e., overlapping of processes for the PM and ongoing tasks) and emotional valence of the stimuli, comparing the patient's performance with that of a control group. We found that the mMDT damage led to deficits in PM that were modulated by focality and emotional valence. OG indeed showed: a greater cost in the ongoing performance when a non-focal PM task was added; a slowing down in retrieving the intentions, in particular when these were associated with focal PM cues; an abnormal performance in the task with positive PM cues. Our findings provide evidence of a contribution of mMDT to PM and suggest a modulation of prefrontal-dependent strategic monitoring and a possible interaction with the limbic structures in the integration of emotion and PM processes. They also give support to the still controversial idea that connections with the perirhinal cortex mediate familiarity-based recognition.

The Regulatory Role of the Human Mediodorsal Thalamus

“…Executive functions, attention control , prospective memory, arousal, motivation, language, and behavioral deficits are also often reported in the acute phase of focal MD lesions 44 , 45 , but in general LTM deficits outlast them [33] . At the chronic phase (>3 months after lesion onset), most patients have a poorly defined complaint of being less efficient or having slight memory problems.…”

Resting‐state pulvinar‐posterior parietal decoupling in PTSD and its dissociative subtype

“…Here, the mediodorsal nucleus presents as an interesting thalamic structure given its reciprocal connectivity with regions underlying executive functions (Golden, Graff-Radford, Jones, & Benarroch, 2017), memory (Cona, Laera, Edelstyn, & Bisiacchi, 2018), and emotion-all factors involved in the posttraumatic response (Metzger, 2010). Accordingly, additional research is urged to identify the effects of trauma on the binding properties and ability of the pulvinar to modulate alpha, as these activities may be central to the restoration of large-scale networks in PTSD and may inform further novel adjunctive treatments for PTSD, such as neurofeedback .…”

“…In addition, it is critical that future research investigates the connectivity of additional highorder thalamic nuclei to determine whether rsFC reductions are a global thalamic phenomenon in PTSD or are specific to the pulvinar nuclei. Here, the mediodorsal nucleus presents as an interesting thalamic structure given its reciprocal connectivity with regions underlying executive functions (Golden, Graff-Radford, Jones, & Benarroch, 2017), memory (Cona, Laera, Edelstyn, & Bisiacchi, 2018), and emotion-all factors involved in the posttraumatic response (Metzger, 2010).…”