Temporal Information Entropy of the Blood-Oxygenation Level-Dependent Signals Increases in the Activated Human...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Time-domain analysis of blood-oxygen-level-dependent (BOLD) signals aids in identifying brain regions activated by stimuli.
• Characterizing information encoded in the temporal dynamics of BOLD signals within activated clusters remains underexplored.

Purpose of the Study:

• To investigate spatial and temporal information encoding within the BOLD signal of the human visual cortex during photic stimulation.
• To analyze information processing in the primary visual cortex (V1) using Shannon entropy.

Main Methods:

• Utilized Shannon entropy to quantify spatial and temporal information in BOLD signals.
• Analyzed BOLD signal distribution within small, highly activated voxel clusters in V1 during rest and stimulation.
• Focused on contralateral V1 during hemifield photic stimulation.

Main Results:

• Observed significant increases in temporal information entropy (2-4%) in contralateral V1 during activation.
• Noted a corresponding decrease in spatial information entropy in contralateral V1.
• Found increased spatial and temporal mutual information in contralateral V1.
• No significant changes were observed in ipsilateral V1.

Conclusions:

• The first cortical stage of visual processing involves a spatiotemporal rearrangement of intracluster BOLD responses.
• BOLD mapping's spatial resolution limitations may obscure functional specialization of small neuronal populations.
• Temporal domain analysis of BOLD signals, specifically increased temporal information entropy, can reveal information encoding not captured by spatial maps.