Human Memory

Which Part of the Brain Controls Memory?

There are three main areas of the brain: the cerebrum, the cerebellum, and the brain stem. As well as hemispheres and lobes. They play key roles in encoding, storing, and retrieving memories.

Consisting of three main areas: cerebrum, cerebellum, and the brain stem. These parts of the human brain serve in the creation of memories, storing memories, and the retrieval of memories. Working in unison the brain allows for a person to control their memories.


The brain is far more intricate than a few bits and pieces stitched together. After all, this is the organ that built the pyramids, painted the Sistine Chapel, wrote Shakespearean sonnets, and landed on the moon.


There are 86 million neurons in the brain, forming a dense network of pathways. While we’re nowhere close to a comprehensive understanding of this three-pound organ, we can localize certain functions and aspects to specific regions, including memory.


What are the Areas of the Brain?


There are three main areas of the brain: the cerebrum, the cerebellum, and the brain stem.


1. Cerebrum


When most people picture the brain, they’re looking at the cerebrum. The wrinkled appearance is the evolutionary consequence of forming hills (gyri) and valleys (sulci) to maximize computational power given limited volume.


As this part is approximately 85% of total brain weight, it’s no surprise it has a long list of jobs to do. The cerebrum controls higher functions like reasoning, speech, and emotion, as well as touch, sight and hearing, and many other responsibilities.


2. Cerebellum


Tucked neatly away, the cerebellum accounts for only 10% of brain mass. However, it’s integral for motor control as well as maintaining balance and posture. Without this “little brain,” you would be unable to enact virtually all physical movement.


3. Brainstem


The brainstem connects the cerebrum and cerebellum to the spinal cord, thus relaying their messages and instructions throughout the body. While acting as this communication hub, the brain stem also controls automatic functions like breathing, temperature, digestion, swallowing, and sleep cycles.




How is the Brain Divided?


Delving deeper into the cerebrum, we find that this organ can be further separated into more minor constituents.


1. The Left and Right Hemispheres


The cerebrum is split into two halves (hemispheres), colloquially referred to as the left and right sides of the brain. The left hemisphere controls the right side of the body, whilst the right hemisphere controls the left side of the body. This explains why victims of right-hemisphere strokes experience paralysis or sensory impairment on the left side of the body.


The left hemisphere is credited for logic, analytical, reasoning, language and numerical skills. Conversely, the right hemisphere takes charge of creativity, imagination, intuition and spatial awareness.


As the two sides constantly communicate through the corpus callosum, a collection of nerve fibers between linking the two halves, you’re able to engage both hemispheres simultaneously, necessary for countless cognitive feats and voluntary movements.


2. Lobes of the Brain


The brain is almost symmetrical, with only slight morphological inconsistency. As a result, each hemisphere contains four lobes: frontal, parietal, occipital and temporal.


Frontal Lobe: controls executive functions, cognitive abilities such as problem-solving, planning and decision-making, as well as personality


Parietal Lobe: processes sensory information (temperature, touch, taste) while allowing for visuospatial processing (tracking objects and avoiding collisions)


Occipital Lobe: primarily responsible for visual perception


Temporal Lobe: enables auditory processing (sound, speech, music), while playing a vital role for memory and language skills


Imagine your brain as a submarine. The frontal lobe can be likened to the captain, leading the vessel and coordinating everything. The parietal lobe is a sonar operator, processing how the submarine is interacting with stimuli and the surroundings. As the occipital lobe is largely vision, we can think of it as the periscope. Finally, the temporal lobe is comparable to a radioman, controlling communications and sending messages.


Just as with an actual submarine crew, where each member is expected to diversify their skillset and develop strong teamwork, the lobes of the brain share certain responsibilities and do not function alone. For example, language is interpreted in the temporal lobe, but formed in the frontal lobe.


How does Memory work?


Memory is a highly complex process that depends on three stages:

  • Encoding: assessing the importance of information and deciding if it’s worth keeping
  • Storing: keeping the information in such a state as to be available as needed
  • Recalling: the retrieval of information, which we experience as remembering


Your brain is continually evaluating the relevance and significance of information. When you consciously try to remember information, you employ your short-term memory. If there is value in storing the information for a longer duration, your mind will work to transfer information to the long-term memory.


1. Short-term Memory


Short-term memory (STM) belongs to the prefrontal cortex (the very front of the frontal lobe). It is our capacity to a small selection of information for a short time.


In his famous paper, titled The Magical Number Seven, Plus or Minus Two, psychologist George Miller proposes that we hold between 5 and 9 items in our STM. It’s generally acknowledged that the length of STM is 20 to 30 seconds.


STM memory is in constant use throughout the course of your day. Examples include:

  • Remembering a number sequence, like a code or phone number
  • Tracking progress when following a set of instructions
  • While reading, retaining the previous sentence to better understand the next
  • Keeping track of topics covered in a conversation
  • Carrying over a number in a math calculation


These nuggets of information are forgotten when they are no longer useful. Through both conscious and unconscious effort, information can be transferred to long-term memory, where it will be kept indefinitely.


It is possible to improve short-term memory by training your memorization and visualization skills, as well as making favorable dietary changes, for example foods rich in omega-3. Use the memoryOS app to get more guidance on enhancing memory and harness the full power of your brain!


2. Long-term Memory


Long-term memory (LTM) occurs in the hippocampus (an area of the temporal lobe). It’s our capacity to store a large collection of information for a long time.


When information is recognized to be significant, it will be taken to long-term memory. Compelling events that provoke emotional reactions, whether joyful or traumatic, are highly likely to end up in LTM.


LTM is used as needed, often triggered by environmental stimuli or behavioral cues. Examples include:

  • Remembering experiences and events
  • Retaining skills from a previous job
  • Intuitively remembering how to ride a bike
  • Recalling facts and figures in an exam
  • Memorizing a public speech


The total capacity of LTM is unknown, both in terms of number of items stored and the duration of storage. Your most treasured experiences, emotional connections and sense of self are all stored in the LTM


3. Working Memory


Some experts consider working memory to be synonymous with short-term memory, whilst others argue they are two distinct modes of operation. The distinction that many psychologists make is that short-term memory is for storage only, whilst working memory is for storage and manipulation of information.


In this sense, working memory is used to refer to the entire theoretical framework of temporary memory structures and processes, of which STM is one part.


Where are Memories Stored in the Brain?


It would be very convenient for neuroscientists if all our memories were stored in one area of the brain, but that’s not the case. Different regions are home to different types of memory. For example, there are two types of long-term memory: explicit (declarative, conscious) and implicit (non-declarative, unconscious). The former requires the hippocampus, neocortex and the amygdala, while the latter relies on the cerebellum and basal ganglia.


1. Explicit Memory


Information stored in your explicit memory requires conscious effort to be recalled. Episodic (past events) and semantic (concepts, general knowledge) memory is explicit, meaning you can access them freely. Three areas of the brain coordinate in order for explicit memory to occur.


Hippocampus: Derived from the Greek hippos (horse) and kampos (sea monster), the hippocampus was named such as this structure was thought to resemble a seahorse. Firmly embedded within the temporal lobe, the hippocampus plays a vital role for explicit memory.


During a lobotomy in 1953, Henry Molaison had his hippocampus removed in order to treat his severe epilepsy. Remarkably, the operation cured his epilepsy, but resulted in the patient’s complete inability to form new memories, only able to rely on experiences that predated his surgery.


In 1985, renowned musicologist Clive Wearing caught a herpes simplex virus, typically only resulting in cold sores. In rare instances, it attacks the spinal cord or brain. For Wearing, the damage was to the hippocampus, leading to the worst known case of amnesia. He spends his day in 20-30 second loops of neurological restart. He has a complete inability to encode new memories.


These case studies indicate that the hippocampus is crucial for explicit memory function, though it is not the only region for storing memory – Molaison was still able to recall the past, while Wearing could still enact implicit motor learning, which we now know occurs in the basal ganglia and cerebellum. Such stories make it clear that forming lasting long-term memories cannot be done without the hippocampus.


Neocortex


The neocortex spans across the lobes of the brain. In fact, 76% of entire brain volume is neocortex. It’s a sheet of neural tissue that forms the outer surface of the brain. The neocortex has a vital role in the person’s semantic memory, your extensive records of concepts, general knowledge and language.


This crucial component of the brain is essential for episodic memory, the account of what has previously happened, from childhood memories to a social gathering last week. However, it is thought that the transfer of memories from the hippocampus to other regions happens while we’re sleeping. If you want to maximize your chances of retaining information, a good night’s sleep is non-negotiable.


Amygdala


The amygdala is a small structure within the temporal lobe, named such because it bears the shape of an almond (Greek: amygdale). It’s a hub for emotions, meaning it’s particularly good at attaching emotion to memories. The amygdala doesn't just influence emotional significance of memories, but also helps to form new ones, especially those to do with fear. After only a few repetitions, fearful memories are formed.


This ‘fear learning’ likely played a key role in survival, much like our “fight or flight” response, which also happens in the amygdala. It has been shown that emotions help to form lasting memories by effectively ‘tagging’ a memory as important because of the emotional weight.


Recent research leans towards the amygdala as integral for encoding new memory, acting as a sort of inner voice that tells the brain what is worth storing.


2. Implicit memory


Information stored in your implicit memory cannot be consciously accessed, such as procedural memory, the ability to perform physical actions without thinking – often called “muscle memory”. Another example is priming, whereby exposure to one stimulus will trigger an associated memory. Two areas of the brain coordinate in order for implicit memory to occur.


Basal ganglia: Involved in a wide range of processes, including habit-formation, learning and reward-processing, the basal ganglia are structures buried deep in the brain. With regard to implicit memory, they are principally tied to procedural memory, more specifically motor skills.


You require the basal ganglia to coordinate movements like dancing, sports, or the playing of a musical instrument. The connection between muscle movement and this region of the brain has been proven through the study of Parkinson’s disease, a condition that leaves the basal ganglia damaged and the patient physically impaired.


Cerebellum: As we learned, the cerebellum is the “little brain” underneath the cerebrum. The cerebellum is vital for fine-motor skills, our ability to handle tools or navigate a cellphone. Accordingly, it is needed to process procedural memories, instructions on how to do something.


Traditionally, the cerebellum is only concerned with motor skills, but recent research involving PET scans showed measurable activity in the cerebellum when participants consciously recalled an episodic memory. This suggests that the cerebellum is also important for certain explicit memory functions.


FAQ


Which part of the brain is responsible for memory?


There are five main areas associated with memory: the hippocampus, neocortex, amygdala, basal ganglia and cerebellum. The hippocampus is associated with declarative and episodic memory. The neocortex appears is used for semantic memory. The amygdala is involved in emotional memories, especially the fearful. The basal ganglia and cerebellum play prime roles for procedural memories.


Which part of the brain controls short-term memory?


Short-term memory depends most heavily on the prefrontal cortex, yet the entire process is thought to be a dynamic relationship between multiple areas of the brain.


Which part of the brain controls long-term memory?


Information is transferred from short-term memory to long-term memory through the hippocampus. Once in long-term memory, information can travel to various places in the brain, including the cerebellum and neocortex.


Can I improve my memory?


It is possible to enhance your encoding, the skill required to consolidate memories from short-term to long-term storage. This can be done through conscious training, including picture exercises, visualization techniques and puzzles.


Although long-term memory is less malleable, studies suggest that memory recall can be improved by regular mental exercises. Improve your memory with the memoryOS app today!

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Contributors:
Alex Ruzhytskyi

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