Exploring Starlab’s EEG Cognitive Tasks Battery: The N-Back Task & Working Memory

Understanding the N-Back Task and Its Role in Working Memory

In our ongoing exploration of Starlab’s EEG Cognitive Tasks Battery, we have previously discussed the Auditory Steady-State Response (ASSR), Resting-State EEG, and the Auditory Oddball task. Now, we turn our attention to the N-back task, a widely used paradigm to assess working memory—the brain’s ability to temporarily store and manipulate information.

The N-back task is a cognitive challenge where participants view a sequence of numbers on a screen and respond based on predefined rules. We incorporate two conditions to assess different levels of working memory load:

0-Back Condition (Low Working Memory Load)

• No need to remember previous numbers—participants only identify a predefined target number.

• Example: Press the red button if the number is 7; press the blue button otherwise.

• This condition primarily engages attention and response selection, requiring minimal working memory.

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1-Back Condition (Higher Working Memory Demand)

• Participants must compare each number to the previous one:

  • ✅ Press the red button if the current number matches the previous one.

  • ❌ Press the blue button if it is different.

• This condition requires continuous updating and maintenance of information, making it a more demanding test of working memory.

Figure 1. Illustration of the N-Back Task:  In the 0-back condition, participants respond only to a predefined target number, requiring minimal working memory. In the 1-back condition, participants compare each number to the one before, demanding continuous memory updating. The increasing cognitive load from 0-back to 1-back reflects the brain’s ability to store and manipulate information in real time.

Neural Signatures of Working Memory: PNwm

One of the key EEG markers associated with working memory during the N-back task is PNwm. This neural component is linked to working memory processing and reflects the brain’s ability to efficiently track and update relevant information. Studying PNwm provides valuable insights into cognitive function and potential impairments.

Investigating Working Memory Deficits in Alzheimer’s Disease

At Starlab, in collaboration with Ace Alzheimer Center Barcelona, we recently conducted a study examining EEG data from participants with:

• Subjective Cognitive Decline (SCD)

• Mild Cognitive Impairment without Alzheimer’s biomarkers (MCI-)

• Mild Cognitive Impairment with Alzheimer’s biomarkers (MCI+)

Key Findings

Our results showed a significant reduction in PNwm in MCI+ patients. This suggests that individuals with Alzheimer’s biomarkers already exhibit early deficits in working memory processing. These findings align with growing evidence that working memory impairments emerge in the preclinical and prodromal stages of Alzheimer’s disease.

Figure 2. Event-Related Potentials (ERP) for the N-back task (1-back minus 0-back) across the three participant groups: SCD, MCI-, and MCI+. The PNwm, a negative deflection occurring between 300 ms and 600 ms, is visibly reduced in MCI+ patients, indicating early deficits in working memory processing associated with Alzheimer’s biomarkers.

Why This Matters

Understanding these early neural changes is critical for improving early diagnosis and intervention strategies for Alzheimer’s disease. EEG-based cognitive assessments, such as the N-back task, can help identify subtle cognitive impairments before clinical symptoms become apparent.

Stay tuned as we continue to explore how EEG can reveal crucial insights into cognitive function, brain health, and neurodegenerative disorders.

About Starlab

Starlab is dedicated to advancing neuroscience through cutting-edge EEG research. Our Cognitive Tasks Battery provides a powerful framework for understanding brain function in both healthy individuals and clinical populations.

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