Dissociable spatial and non-spatial attentional deficits after circumscribed thalamic stroke

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurology

Background:

• Thalamic nuclei are crucial for sensory, motor, and cognitive functions, including attention.
• Attentional deficits are common after thalamic stroke, but the specific roles of thalamic subregions remain unclear.
• The Theory of Visual Attention (TVA) provides a framework to measure distinct attentional parameters.

Purpose of the Study:

• To investigate the functional relevance of specific thalamic nuclei and vascular territories for distinct attentional subfunctions.
• To correlate lesion locations within the thalamus with specific attentional deficits using parameter-based assessment and lesion symptom mapping.

Main Methods:

• Studied 16 patients with focal thalamic lesions and compared them to 52 age-matched controls.
• Assessed four attentional parameters using the Theory of Visual Attention (TVA): visual short-term memory storage capacity (VSTM), processing speed, selective control, and spatial weighting.
• Performed lesion symptom mapping in standard stereotactic space to identify the relationship between lesion location and attentional deficits.

Main Results:

• Thalamic lesion patients showed mild group-level impairments in visual processing speed and VSTM.
• Lateral thalamic lesions were associated with deficits in processing speed.
• Medial thalamic lesions were linked to spatial bias and extinction phenomena.
• A posterior thalamic lesion case demonstrated an ipsilesional spatial bias, consistent with the Neural Theory of Visual Attention (NTVA).
• An anterior-medial thalamic lesion case exhibited reduced selective attentional control.

Conclusions:

• Distinct vascular subregions of the thalamus are associated with specific attentional syndromes.
• Lateral thalamic lesions primarily affect visual processing speed.
• Medial thalamic lesions are associated with spatial attentional biases and extinction.