Thalamic activation during an attention-to-prepulse startle modification paradigm: a functional MRI study

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Prepulse inhibition (PPI) of the startle reflex is a measure of early information processing.
• Selective attention modulates PPI, with medial frontal-thalamic circuitry implicated in animal models.
• Previous research lacked human functional neuroimaging data on attention's effect on PPI circuitry.

Purpose of the Study:

• To investigate differential brain activation within the medial frontal-thalamic circuitry during attended versus ignored prepulse inhibition (PPI) using fMRI.
• To examine the role of attention in modulating brain responses related to PPI.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was performed on ten healthy subjects.
• Subjects listened to attended and ignored tones as prepulses to a startle stimulus during fMRI.
• Regions of interest were identified on structural MRI and coregistered to fMRI data.

Main Results:

• The right thalamus, including anterior and mediodorsal nuclei, showed greater fMRI response to attended PPI than ignored PPI.
• The startle-alone condition resulted in deactivation in these thalamic regions.
• The transitional medial cortex (Brodmann Area 32) exhibited varied responses based on attention and stimulus conditions.

Conclusions:

• Findings support the involvement of the thalamus in modulating PPI in humans, extending previous animal model research.
• This study provides a foundation for further fMRI investigations into the neural circuitry of PPI modulation.
• Understanding these mechanisms is crucial for studying normal and disordered PPI modulation.