Memory

Original Editor - Cindy John- Chu Top Contributors - Cindy John-Chu, Lucinda hampton, Nikhil Benhur Abburi, Umamah Ejaz, Tolulope Adeniji, Ewa Jaraczewska, Vidya Acharya, Rucha Gadgil, Naomi O'Reilly and Kim Jackson

Introduction

A cognitive model

Memory is the brain’s ability to encode, store, and retrieve information when needed. It plays a vital role in enabling us to carry out everyday tasks, build relationships, learn new things, and grow as individuals. In essence, memory shapes our experiences and forms the foundation of our identity.

Memories are stored in the brain through the strengthening of synaptic connections between neurons. Key structures involved in memory processing include the hippocampus, parahippocampal gyrus, fornix, mammillary bodies, and cingulate gyrus.

However, memory function is not always flawless. With age, it may take longer to recall information, reflecting the natural changes in the brain over time.

Formation of Memory

The areas of the human brain involved in memory formation.

To form new memories, information must first be transformed into a usable format through a process called encoding. Once encoded, the information is stored in the brain for future use. Although most stored memories remain outside our conscious awareness, they can be accessed when needed through the process of retrieval, which brings them into conscious thought.

Key regions of the brain involved in memory formation include the hippocampus, cingulate cortex, prefrontal cortex, and amygdala.

Types of Memory

Three main categories of memory have been identified namely as:

• Immediate memory (sensory amd working memory)
• Short-term memory
• Long-term memory

Sensory Memory

Structure of brain

Sensory memory (SM) is the shortest form of memory, responsible for briefly storing impressions of sensory information after the original stimulus has ended. It captures input from the five senses with high accuracy but for a very limited duration. This type of memory is stored automatically and cannot be extended through rehearsal. Sensory memory transitions into short-term memory through the process of attention, which involves selectively focusing on specific aspects of the environment while filtering out irrelevant stimuli.

Working Memory

Working memory is a temporary storage system with limited capacity that actively holds and manipulates information needed for ongoing cognitive tasks such as comprehension, learning, and reasoning. It involves passive storage and active processing. It is sometimes considered a form of procedural short-term memory due to its active manipulation of information.

Short-Term Memory

Short-term memory (STM) refers to the temporary storage of information for a brief period, typically lasting a few seconds. It results from the conscious effort to retain sensory input within that limited time frame..Short-term memory (STM), also referred to as primary or working memory, involves the simultaneous processing and temporary storage of information. It holds a limited amount of data for a brief duration, typically between 15 seconds and 1 minute. STM can be transferred into long-term memory through a process called consolidation, which is strengthened by repetition, meaningful associations with prior knowledge, and personal interest in the material. The prefrontal cortex plays a key role in managing short-term memory functions.

Long-Term Memory

Model of working memory operation in the spiking neuron network accompanied by astrocytes.

Short-term memory (STM), also known as working memory, allows us to hold and use small amounts of information for a brief period—typically between 15 seconds and 1 minute. It enables us to remember and process information at the same time. Through a process called consolidation, STM can turn into long-term memory. This process is supported by repetition, connecting new information to what we already know, or paying close attention to topics we find interesting. The prefrontal cortex is the main brain region involved in short-term memory.

Long-term memory is usually divided into two types:

• Explicit memory (also called declarative memory) includes memories we are aware of, such as facts and events. It has two parts: episodic memory, which is about personal experiences or specific events, and semantic memory, which is about general knowledge, like facts about the world.
• Implicit memory is mostly unconscious and includes things we do without thinking, like skills and habits. This includes procedural memory, such as knowing how to drive a car, ride a bike, or use a computer.

False Memories

Imagination

We often think of memory as a camera that captures moments exactly as they happened, but in reality, it's more like a collage—pieces of information put together, sometimes with mistakes or added details. Research has shown that human memory is quite fragile. We can easily make errors, and even small suggestions can lead to false memories.

Although scientists are still studying how false memories form, it's clear that they can happen to almost anyone.

People can be influenced to remember their past differently—and sometimes even recall entire events that never actually happened. When this happens, they may feel very confident in these false memories and can describe them in great detail. Studies like these help explain why some people strongly believe in memories that are clearly impossible, such as events that couldn’t have happened due to biology or geography.

Memory Difficulties in Neurological and Psychiatric Conditions

Memory impairment is highly prevalent in people with neurological and psychiatric conditions, with consequences such as reduction in independence and complicating rehabilitation processes. One example of this is in progressive conditions like Alzheimer’s disease, where the memory decline usually begins with episodic memory (such as recalling recent conversations) and eventually affects both semantic and procedural memory systems. Individuals with vascular dementia may experience difficulties with memory retention, particularly with transient information, but they typically struggle more with attention and planning. Along with concentration issues, hallucinations, and motor symptoms, people with Lewy body dementia also struggle with episodic memory

Mental health conditions like depression can cause problems with working memory and recall, especially in older adults, and their symptoms can mimic those of early-stage dementia. PTSD sufferers may experience unpleasant flashbacks and have trouble recalling unrelated events. Another condition in which people commonly struggle with verbal memory and learning, making it difficult for them to carry out daily tasks and participate in social activities, is schizophrenia.

Memory Assessment

The following are the lists for evaluating an individual memory functions:

1. Wechsler Memory Scale

2. Word-listing learning and memory

How to Improve Memory

There are several ways to support and improve memory, including eating a healthy diet, exercising regularly, not smoking, keeping blood sugar, cholesterol, and blood pressure at normal levels, and avoiding a sedentary lifestyle. A book review by Sleister (2014) also highlighted that retrieval practice—a method of actively recalling previously learned information—can strengthen and improve memory over time.

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Disorders of Memory

It's normal to forget things once in a while. e.g., where we put our keys. People who forget things more often than others may have mild cognitive impairment. Prolong memory issues can also have an underlying pathology like below:

• Alzheimer's Disease
• Other types of ⁣⁣dementia
• Stroke
• Depression
• Head Trauma
• Brain Metastasis
• Kidney, Liver, or Thyroid problems
• Reactions to certain medicines
• Substance use
• AmnesiasSee how memories can have adverse effects, links below.
• Post Traumatic Stress Disorder
• Mental health and Forced Displacement
• Mental Health Stress and Resilience in Times of COVID-19