The hippocampus, amygdala, and cerebellum play important roles in the consolidation and manipulation of memory.
Learning Objectives
Analyze the role each brain structure involved in memory formation and consolidation
Key Points
Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition.
The hippocampus is essential for the consolidation of both short-term and long-term memories. Damage to this area of the brain can render a person incapable of making new memories and may even affect older memories that have not been fully consolidated.
The amygdala has been associated with enhanced retention of memory. Because of this, it is thought to modulate memory consolidation. The effect is most pronounced in emotionally charged events.
The cerebellum is associated with creativity and innovation. It is theorized that all processes of working memory are adaptively modeled by the cerebellum.
Key Terms
declarative memory: The type of long-term memory that stores facts and events; also known as conscious or explicit memory.
encoding: The process of converting information into a construct that can be stored within the brain.
consolidation: The act or process of turning short-term memories into more permanent, long-term memories.
Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition. Like encoding, consolidation affects how well a memory will be remembered after it is stored: if it is encoded and consolidated well, the memory will be easily retrieved in full detail, but if encoding or consolidation is neglected, the memory will not be retrieved or may not be accurate.
Consolidation occurs through communication between several parts of the brain, including the hippocampus, the amygdala, and the cerebellum.
The Hippocampus
While psychologists and neuroscientists debate the exact role of the hippocampus, they generally agree that it plays an essential role in both the formation of new memories about experienced events and declarative memory (which handles facts and knowledge rather than motor skills). The hippocampus is critical to the formation of memories of events and facts.
Figure 1. The hippocampus: The hippocampus is integral in consolidating memories from short-term to long-term memory.
Information regarding an event is not instantaneously stored in long-term memory. Instead, sensory details from the event are slowly assimilated into long-term storage over time through the process of consolidation. Some evidence supports the idea that, although these forms of memory often last a lifetime, the hippocampus ceases to play a crucial role in the retention of memory after the period of consolidation.
Damage to the hippocampus usually results in difficulties forming new memories, or anterograde amnesia, and normally also brings about problems accessing memories that were created prior to the damage, or retrograde amnesia. A famous case study that made this theory plausible is the story of a patient known as HM: After his hippocampus was removed in an effort to cure his epilepsy, he lost the ability to form memories. People with damage to the
hippocampus may still be able to learn new skills, however, because those types of memory are non-declarative. Damage may not affect much older memories. All this contributes to the idea that the hippocampus may not be crucial in memory retention in the post-consolidation stages.
Figure 2. The amygdala: The amygdala is involved in enhancing the consolidation of emotional memories.
The Amygdala
The amygdala is involved in memory consolidation—specifically, in how consolidation is modulated. “Modulation” refers to the strength with which a memory is consolidated. In particular, it appears that emotional arousal following an event influences the strength of the subsequent memory. Greater emotional arousal following learning enhances a person’s retention of that stimulus.
The amygdala is involved in mediating the effects of emotional arousal on the strength of the memory of an event. Even if the amygdala is damaged, memories can still be encoded. The amygdala is most helpful in enhancing the memories of emotionally charged events, such as recalling all of the details on a day when you experienced a traumatic accident.
Figure 3. The cerebellum: A vertical cross-section of the human cerebellum, showing the folding pattern of the cortex, and interior structures.
The Cerebellum
The cerebellum plays a role in the learning of procedural memory (i.e., routine, “practiced” skills), and motor learning, such as skills requiring coordination and fine motor control. Playing a musical instrument, driving a car, and riding a bike are examples of skills requiring procedural memory. The cerebellum is more generally involved in motor learning, and damage to it can result in problems with movement; specifically, it is thought to coordinate the timing and accuracy of movements, and to make long-term changes (learning) to improve these skills. A person with hippocampal damage might still be able to remember how to play the piano but not remember facts about their life. But a person with damage to their cerebellum would have the opposite problem: they would remember their declarative memories, but would have trouble with procedural memories like playing the piano.
