The first neurotransmitter discovered (1921).

Acetylcholine is distributed throughout our brain and especially in centers controlling conscious movement (such as the basal ganglia and motor cortex). It regulates all voluntary muscles and many involuntary muscles, and it’s the primary neurotransmitter for the parasympathetic nervous system (rest and recuperation). It’s estimated that as many as 10% of our brain’s synapses use acetylcholine, and its action is generally excitatory. It’s also active in learning and memory circuits. People with Alzheimer’s disease suffer from a depletion of functional acetylcholine neurons in the hippocampus.

A molecule that can function both as a hormone (synthesized in the adrenal glands) and as a neurotransmitter (called epinephrine). It helps to activate body-brain systems, especially during stress responses.

A condition in which people with a functioning sensory system are unable to recognize objects, people, places, or events that should be familiar. Agnosia means “not knowing.”

Agnosia typically occurs because of damage to specific brain regions that interpret sensory information. Other interpretive regions may be functional. For example, someone with prosopagnosia can’t recognize a friend’s face but can recognize her voice; someone with color agnosia can’t recognize different colors despite functioning visual and language systems; and someone with gustatory agnosia can’t recognize and discriminate among tastes.

The chemical building blocks of proteins and of neurotransmitters.

Four types of molecules provide the construction base of all organisms: amino acids, fatty acids, nucleotides, and sugars. Amino acids and peptides (small combinations of amino acids) can function as neurotransmitters, and longer amino acid chains and proteins can function as the receptors on neurons to which neurotransmitters attach and pass information from the presynaptic to the postsynaptic neuron.

A breakdown of part or all of the cognitive processes that store and recall memories.

Amnesia can result from trauma, disease, tumor, stroke, or dementia occurring in the brain regions that process memory and from encephalitis or chronic alcoholism (Korsakoff’s syndrome). Amnesia most often occurs in our long-term declarative (factual and autobiographical) memory systems. Although many specific kinds of memory loss have been clinically identified, retrograde and anterograde amnesia are perhaps the most common (and some people suffer from both).

Retrograde amnesia is the inability to recall any declarative information that was stored prior to the damage (which typically occurred in the Temporal lobe areas that are central to the processing of declarative memories).

Anterograde amnesia is the inability to store and recall declarative information that emerges after damage to declarative memory processing systems, although these amnesiacs can recall information from periods prior to the damage. Perhaps the best-known case of anterograde amnesia is a man commonly called HM who had most of his hippocampus and amygdala surgically removed at age 27 (1953) in an attempt to stop his epileptic seizures. It helped his epilepsy but left him with profound anterograde amnesia. Since then, HM has been unable to store or recall any new declarative information, although he can recall memories from before the surgery, and he can develop new procedural (skill) memories. He basically lives within the world of short-term memory (a few minutes at most). HM became the most-studied amnesiac in medical history, and much of what scientists initially learned about declarative memory and amnesia resulted from these studies.

You could functionally explain amnesia as follows: Think of a computerized warehouse in which materials are stored before being retrieved and sent to customers. Suppose that the computer and database that contain the location of the stored materials becomes dysfunctional. That would be a situation somewhat similar to retrograde amnesia. Suppose again that new shipments of materials arrived to be stored within the warehouse, but the dysfunctional computer and database can’t specify where the new materials should be stored. That would be a situation somewhat similar to anterograde amnesia. See Figures 6 and 8.

A paired complex of structures the shape and size of an almond that recognize innate biological fears and activate relevant primal automatic responses. It is often called the “Fear Button.”

The amygdala is located in the lower frontal areas of the two Temporal lobes. Place a finger on either temple, and an amygdala will be about 1.5 inches into your brain.

If incoming sensory information that passes through the amygdala portends imminent danger (such as a sudden movement or loud sound), the amygdala will rapidly signal the nearby hypothalamus to initiate an appropriate response (fight, flight, freeze). Fearful information is simultaneously sent into the cingulate area of the cortex for conscious thought about alternate responses if the danger isn’t imminent. The amygdala also adds positive and negative emotional content to the memory of an experience for use in subsequent similar situations, thus playing an important role in the consolidation of long-term memories that occurs in various brain areas. See Figure 8.

A peptide that triggers drinking behaviors when body fluid levels are low.

A (typically) left-hemisphere region located posterior to Wernicke’s area, at the juncture of the occipital, parietal, and Temporal lobes. It connects the initial visual word recognition process to other elements of language comprehension and production that are principally processed in forward regions of our brain. See Figure 6.

A commissure is a bundle of myelinated axons that link and exchange information between the two cerebral hemispheres. The anterior commissure exchanges emotional information between the unconscious subcortical areas of the two hemispheres. It’s located below and toward the front of the corpus callosum, a much larger commissure that exchanges conscious thought between the hemispheres. Some evidence exists that both commissures are typically larger in females than in males. See Figure 7.

An unpleasant emotional state that’s focused on potentially negative events. It exists along a continuum from mild concern to intense fear.

Emotional arousal occurs in response to a looming danger or opportunity. Anxiety adds a feeling of apprehension to emotional arousal—a feeling that a real or imagined challenge will result in a negative outcome because we lack the resources to respond successfully. It’s normal for feelings of anxiety to emerge periodically during the course of the day as we try to meet a variety of commitments, but anxiety becomes dysfunctional when dread and doom dominate our thoughts and activities.

Symptoms of a dysfunctional anxiety include irregularities in circulation, respiration, and appetite and digestion; headaches; generalized aches and pains; fatigue; and an inability to relax. Phobias, panic disorder, and obsessive-compulsive disorder are some of the specific manifestations of dysfunctional anxiety. Such anxiety disorders emerge when a response that is normally appropriate and useful (such as fear of falling) becomes excessive and limiting (such as in refusing to use elevators or airplanes).

See also Stress

A general term for an impaired ability or a complete loss of ability to understand or express some element of language.

Aphasia typically occurs following stroke or traumatic damage to some part of our brain’s language-processing areas, or because of delayed brain development. Global aphasia is a complete inability to process language, but the lost function in the many other types of aphasia is limited and quite specific. Language is a complex activity that requires the collaboration of many separate brain areas. In nonglobal aphasia, one or more language-processing areas become dysfunctional, but others do not. For example, someone with anomia can’t name specific people, objects, or places (or a combination of these), although they recognize them when others identify them; someone with tactile aphasia can’t name touched unseen objects but can name them if viewed; and someone with syntactic aphasia has trouble arranging words in their proper grammatical sequence. The best-known forms of aphasia are Wernicke’s and Broca’s aphasia. In Wernicke’s aphasia, language comprehension is impaired but speech production is not (although speech tends to be error-laden). In Broca’s aphasia, language comprehension is good, but speech is limited and labored at best.

Dyslexia is typically a developmental reading disability in an otherwise intelligent child or adult who is motivated to read and who has had adequate schooling. Dyslexia is not a generalized language defect, but a specific localized functional deficiency in the brain areas that process the sounds of language (phonemes). This results in difficulty in fluent word recognition, decoding, and spelling, which may lead to problems with reading comprehension and vocabulary development. Recent advances suggest that although it isn’t an easily cured condition, early diagnosis and intense intervention can materially improve the reading capabilities of people with dyslexia.

Agraphia is the loss of writing ability, even though arm and hand movements are unimpaired. As with aphasia, an agraphic impairment can be quite specific. Someone with apraxic agraphia can orally spell words but can’t easily write them; someone with spatial agraphia can’t arrange text properly on a page. See Figure 6.

A (typically) left-hemisphere axon pathway that processes language. It originates in neurons in Wernicke’s area in the Temporal lobe, passes through the angular gyrus, and connects with Broca’s area neurons in the frontal lobe. It thus moves language from the original thought impetus to the frontal lobe language production areas.

Think of it as being analogous to a transportation route that takes raw materials to a production site. See Figure 6.

A celebration of conscious human skill and production that elevate ordinary behaviors or objects into something aesthetically extraordinary and transcendent. George Bernard Shaw suggested that we use a mirror to see our face and the arts to see our soul.

Artifacts from early human societies suggest that the arts were always cognitively important. If the arts hadn’t been important, people wouldn’t have expended the considerable time and energy it took to decorate clothing and tools and to make nonfunctional artistic objects (such as necklaces), given the primitive tools and materials available to them.

The arts have endured, and so we’ve also learned much about later cultures via their art. Anouilh, Bach, Cezanne, Da Vinci, and the rest of the arts alphabet live on in today’s theaters, concert halls, and museums.

So why would communities who laud their architecture, museums, musical organizations, and theaters reduce or even eliminate their school arts programs that a quarter of a century ago were staffed by trained profess...