Involvement of the Mediodorsal Nucleus of the Thalamus in Higher Order Cognitive Processes

Study Overview
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Brief Summary
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The aim is to expand evidence about the importance of the mediodorsal nucleus of the thalamus as a key node in human higher-order cognitive functions such as learning, decision-making, and adaptive behavior. Thus, the project proposes to assess global cognition along with higher-order cognition integrity via sensitive behavior tasks in patients with well localized lesions (mediodorsal thalamic infarcts) compared with healthy participants.

Detailed Description
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The recruitment of patients with isolated thalamic lesion after stroke is known to be a challenge that the investigators overcame through the expertise of neurologists within their stroke unit. First, they will describe the cognitive profile consecutive to a lesion of the thalamus, assessed with standardized neuropsychological tests. Second, and more specifically, they will study performances at experimental tasks focusing on higher-order cognition (decision-making, updating, interference managing, multitasking). They will use the automatic localization method already performed : the lesions will be manually segmented from T1 morphologic sequences, and then normalized in a template. Finally a numerical atlas of thalamus will be applied on the lesions, determining the injured substructure and the lesion volume. Besides, this method will be compared with new high resolution thalamus-centered anatomical sequences allowing direct and individual identification of the involved thalamic nucleus.

Official Title
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Involvement of the Mediodorsal Nucleus of the Thalamus in Higher Order Cognitive Processes : a Study in Patients With a Thalamic Infarct

Conditions
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Thalamic Infarction

Intervention / Treatment
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* Other: neuroimaging
* Other: Neuropsychological assessment


Participation Criteria
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Eligibility Criteria
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Inclusion criteria for patients: French as their mother tongue Absence of cognitive deterioration before the stroke. Visual, auditory (equipment authorized) and oral or written skills sufficient for the proper assessment using neuropsychological tests. First infarct affecting the thalamus. At least seven years' schooling from primary school Signed informed consent Chronic lesion (> 3 months) Inclusion criteria for controls: French as their mother tongue Absence of cognitive complain Visual, auditory (equipment authorized) and oral or written skills sufficient for the proper assessment using neuropsychological tests. At least seven years of school from primary school Signed informed consent Exclusion criteria for patients: Neurological deficit or significant residual disability at inclusion. Aphasia, agnosia, apraxia or severe neglect, as demonstrated by clinical examination and neuropsychological tests. Subjects with a contraindication to MRI. General, neurological or psychiatric progressive disease. Exclusion criteria for controls: Subjects with a contraindication to MRI. General, neurological or psychiatric progressive disease.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: patient with first thalamic infarct<br>Patient with first thalamic infarct, they will undergo detailed neuropsychological assessment of memory, language, executive functions and mood along detailed neuroimaging including high-resolution imaging of the thalamus, DTI and resting state fMRI. | Other: neuroimaging<br>* neuroimaging including high-resolution imaging of the thalamus, DTI and resting state fMRI<br>Other: Neuropsychological assessment<br>* neuropsychological assessment of memory, language, executive functions and mood<br>|
| Other: healthy subject matched with control<br>Healthy subject matched with control, they will undergo detailed neuropsychological assessment of memory, language, executive functions and mood along detailed neuroimaging including high-resolution imaging of the thalamus, DTI and resting state fMRI. | Other: neuroimaging<br>* neuroimaging including high-resolution imaging of the thalamus, DTI and resting state fMRI<br>Other: Neuropsychological assessment<br>* neuropsychological assessment of memory, language, executive functions and mood<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Performance at the SET (Six Elements Test) | Performances of patients with a mediodorsal thalamic infarct in tasks assessing higher order cognition compared to healthy participants. Assessment of multitasking : 6 sub-tasks have to be achieved within 15 minutes. They include arithmetic tasks, image naming tasks, and dictation of a known route. Quantitative scores are derived from quantitative et qualitative data, then interpreted with international normative values. | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Performances at the PASAT (Pace Auditory Serial Addition Test) updating during working memory | Performances of patients with a mediodorsal thalamic infarct in sensitive executive tests compared to healthy participants.The PASAT assesses the updating during working memory. | Day 1 | 
| Performances at the Brown-Petterson task | Performances of patients with a mediodorsal thalamic infarct in sensitive executive tests compared to healthy participants. The Brown-Petterson task focuses on the management of interference during working memory. | Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Mediodorsal nucleus, higher order cognition