Glossary
Date Posted: May 1, 2008
In-Depth Report
Glossary
acetylcholine: A chemical neurotransmitter that plays a role in attention, learning, and memory by helping brain cells communicate with each other.
acquisition: The first step in memory formation, in which the brain absorbs new information.
age-related cognitive decline: The slight loss of memory and speed of information processing that occurs with normal aging.
amnesia: A condition caused by brain injury or illness and characterized by an inability to form new long-term memories or to remember earlier ones.
amygdala: A brain structure with strong connections to the hippocampus and other structures of the limbic system that is vital to emotional arousal and the formation of long-term memories.
axon: A long filament-like projection of a neuron that conducts electrical signals away from the neuron cell body (nucleus) to other cells.
cerebral cortex: The outer layer of gray matter surrounding the cerebrum that carries out all aspects of higher brain function including thought, memory, sensation, and voluntary movement.
cognitive function: All of the brain mechanisms involved with thinking, reasoning, learning, and remembering.
cognitive reserve: The capacity of the brain to perform cognitive functions despite neurological damage from conditions such as Alzheimer's disease.
consolidation: A key phase in memory formation, in which the brain transforms newly acquired information into long-term memories.
cortisol: A hormone released by the body in response to physical or emotional stress. High levels of cortisol can damage the regions of the brain that are crucial to memory function.
declarative memory: Memory for facts (semantic memory) and for events (episodic memory); also called explicit memory.
dementia: A progressive decline across multiple cognitive domains, resulting in impairment of everyday function.
dendrite: The small branching part of a neuron that receives electrical impulses from other neurons and relays them to the body (nucleus) of the neuron.
executive functions: A group of cognitive activities that involves the overall regulation of thinking and behavior; the higher-order processes that enable us to plan, sequence, initiate, and sustain our behavior toward some goal, incorporating feedback and making adjustments along the way.
hippocampus: A seahorse-shaped structure situated within the limbic system in the middle of the brain that has a central role in emotion and memory consolidation.
limbic system: A region deep within the brain that is sometimes referred to as the emotional center of the brain. The hippocampus, one of the structures that make up the limbic system, is instrumental in memory formation.
long-term memory: A memory that lasts from a few minutes to decades.
magnetic resonance imaging (MRI): A noninvasive diagnostic radiology procedure that uses magnetic fields to form two-dimensional images of the brain and other internal anatomical structures.
mild cognitive impairment (MCI): A condition characterized by the loss of cognitive function — usually memory — that is more severe than is normal for a person's age, but without obvious impairment in activities of daily living. It is a risk factor for Alzheimer's disease, and some researchers believe MCI is, in fact, early Alzheimer's disease.
neuron: A nerve cell, including its axon and dendrites.
neurotransmitter: A chemical substance that relays electrical signals from one neuron to another.
Pittsburgh Compound B (PIB): A substance that binds to amyloid proteins in the brain (markers for Alzheimer's disease) that makes them visible in living brains under positron emission tomography (PET) scanning.
positron emission tomography (PET): A nuclear medicine imaging technique that uses differences in energy metabolism in different areas of the body to produce a three-dimensional image of functional processes in the brain or other organs.
procedural memory: The long-term memory of skills and procedures, or "how-to" knowledge. Also called implicit memory.
retrieval: The act of recalling previously learned information; it involves the reactivation of particular nerve cell pathways that encoded a given piece of information.
short-term memory: A memory that lasts anywhere from milliseconds to minutes. It consists of primary memory and working memory.
synapse: The junction between two neurons, across which chemical neurotransmitters carry messages.
thalamus: A brain structure located just above the hippocampus that is crucial for integrating and relaying sensory information throughout the brain and has a role in memory consolidation.
white matter: The inner portion of the brain, composed primarily of axons. Messages are sent between different regions of the brain (gray matter) via these nerve fibers.
working memory: A type of short-term memory process that involves temporarily storing and manipulating information.
Review Date: 2008-05-01
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