Sequential working memory refers to a specific aspect of working memory, a cognitive system responsible for temporarily holding and manipulating information in one's mind. In the case of sequential working memory, the focus is on the temporary storage and processing of information in a sequential or ordered fashion. This cognitive function is crucial for tasks that require individuals to remember and manipulate information in a specific sequence, such as following directions, comprehending language, mental calculations, and problem-solving.
Key characteristics of sequential working memory include:
Temporary Storage: It involves holding a series of items, events, or information in one's mind for a brief period. This information can encompass numbers, letters, words, or other stimuli that need to be remembered in a particular order.
Order Maintenance: One of the primary functions of sequential working memory is to maintain the order or sequence of the items. This is especially important in tasks like arithmetic calculations, where the order of operations matters.
Processing and Manipulation: In addition to storage, sequential working memory allows for the manipulation and processing of the information being held. This enables individuals to reorder items mentally, perform mental arithmetic, or understand the structure of a sentence, for example.
Capacity Limit: Like working memory in general, sequential working memory has a limited capacity. The number of items or events that can be effectively held and processed in sequence varies among individuals but typically falls within a range of 5 to 9 items.
Role in Complex Cognitive Functions: Sequential working memory is integral to various higher cognitive functions, including problem-solving, decision-making, language comprehension, and learning. It plays a fundamental role in these processes by facilitating the maintenance and manipulation of information in a sequential manner.
Neurological Basis: Research has identified several brain regions, including the prefrontal cortex and the hippocampus, as being involved in working memory, including sequential working memory. These regions play a significant role in the neural underpinnings of this cognitive function.
Deficits in sequential working memory can affect a person's ability to follow instructions, perform calculations, comprehend complex sentences, and engage in tasks that require processing information in a specific order. Understanding the nature of sequential working memory is vital in fields such as cognitive psychology, education, and neuroscience, as it provides insights into how individuals process and manage information in everyday tasks and problem-solving.
The prefrontal cortex and hippocampus may support sequential working memory beyond episodic memory and spatial navigation. This stereoelectroencephalography (SEEG) study investigated how the dorsolateral prefrontal cortex (DLPFC) interacts with the hippocampus in the online processing of sequential information. Twenty patients with epilepsy (eight women, age 27.6 ± 8.2 years) completed a line ordering task with SEEG recordings over the DLPFC and the hippocampus. Participants showed longer thinking times and more recall errors when asked to arrange random lines clockwise (random trials) than to maintain ordered lines (ordered trials) before recalling the orientation of a particular line. First, the ordering-related increase in thinking time and recall error was associated with a transient theta power increase in the hippocampus and a sustained theta power increase in the DLPFC (3-10 Hz). In particular, the hippocampal theta power increase correlated with the memory precision of line orientation. Second, theta phase coherences between the DLPFC and hippocampus were enhanced for ordering, especially for more precisely memorized lines. Third, the theta band DLPFC → hippocampus influence was selectively enhanced for ordering, especially for more precisely memorized lines. This study suggests that theta oscillations may support DLPFC-hippocampal interactions in the online processing of sequential information 1)
This SEEG study provides interesting insights into the neural mechanisms underlying sequential working memory, emphasizing the role of theta oscillations and DLPFC-hippocampal interactions. While the results are promising, the limited sample size and patient population raise concerns about generalizability. Further research should broaden the scope of tasks and populations to better understand the practical implications of these findings for real-world cognitive functions involving sequential memory.