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ARCUATE ZONE OF THE BRAIN

the bow-shaped portion of the reticular formation on the back of the brain that extends from the spinal cord to

ARIPIPRAZOLE

n. an atypical antipsychotic agent that is thought to bind to the presynaptic D2 dopamine autoreceptor, and thereby inhibit the

AROMATASE

n. an enzyme that works to convert many of the male sex hormones (androgens) into female sex hormones (estrogens). See

AROUSAL-REDUCTION MECHANISM

any stimulus or reaction that decreases the degree of arousal within an individual after arousal has reached an uncomfortably high

ARTERIOVENOUS MALFORMATION (AVM)

an abnormal, congenital tangle of arteries and veins that are directly connected and lack any intervening capillaries. Such malformations may

ARTIFACT

n. 1. an error caused by improper statistical manipulation of experimental data or a logical flaw in experimental design that

ASCENDING RETICULAR ACTIVATING SYSTEM (ARAS)

refers to the pathways that transmit nervous impulses from the reticular formation of the midbrain in an ascending manner through

ASPERGER'S DISORDER

a pervasive developmental disorder associated with varying degrees of deficits in social, emotional and conversational skills, difficulties with set-shifting, and

ASSESSMENT INSTRUMENT

an instrument that is typically used in the evaluation of ability, achievement, interests, personality, psychopathology, or some other factor.

ASSOCIATION FOR RESEARCH IN OTOLARYNGOLOGY (ARO)

an association of scientists and physicians who collectively perform and share research on hearing, balance, speech, taste, and smell. The

ASSOCIATIVE MEMORY

1. a memory of a past event or place that may occur by recalling something associated with it. 2. retrieval

ASTHENIC TYPE

a body type characterized by a long- limbed, narrow-chested, weak looking physique. According to some typologies, such individuals tend to

ASYMMETRICAL DISTRIBUTION

describes a statistical distribution whereby the frequency of scores above the mean does not equal that below the mean.

ATAXIA TELANGIECTASIA

an autosomal recessive genetic disorder characterized by an inability to coordinate voluntary muscle movements (see ataxia) and by the dilation

ATMOSPHERE EFFECT

1. the tendency for particular behaviors to be stimulated by a particular situation, even when inappropriate or completely pointless -

ATTAINMENT

refers to a specific educational achievement or accomplishment. Also refers to the achievement of goals.

ATTENTIONAL CAPTURE

the unintentional focusing of attention, for example by a change in a stimulus, which interrupts other processing - for example,

ATTENUATOR

refers to a calibrated device that accurately controls the intensity of tones or lights on electronic instruments, such as audiometers,

ATTRACTION RELATIONS

refers to patterns of liking-disliking, acceptance-rejection, and inclusion-exclusion among members of a given group. Such patterns may also be known

ATYPICAL CONDUCT DISORDER

in the DSM-lll, this represented a diagnostic category for a disorder that in the DSM-IV-TR, is classified as disruptive behavior