Fundamentals Of Cognitive Neuroscience Glossary - Set 1 - Sheet2 Flashcards
1
Q
Acetylcholine (a-SEE-til-kol-en)
A
A neurotransmitter that functions as a modulator of arousal, memory, and attention during waking states. ACh is generated in the brainstem in the pedunculopontine nucleus and laterodorsal tegmental nucleus and in the frontal lobe in the nucleus basalis. See Chapter 12.
2
Q
Acoustical analysis (uh-KOO-sti-kul uh-NAL-ih-sus)
A
(Greek akoustikos of hearing) The process of interpreting physical sound energy, whether linguistic, musical, or sounds in the environment (as in a door slamming or a car starting). See Chapter 5.
3
Q
Action potential (AK-shun po-TEN-shul)
A
In neurons, an electrochemical signal beginning near the cell body and traveling down the axon to the synaptic terminal. Also called a “spike” or “neuronal firing.” See Chapter 3.
4
Q
Alpha waves (AL-fa WAY-vz)
A
(first letter of the Greek alphabet) A regular electromagnetic wave detected in the brain or on the scalp and apparently reflecting the activity of large populations of neurons. Alpha waves have a frequency of 7.5e13 Hz and originate predominantly from the occipital lobe during periods of waking relaxation with the eyes closed. Conversely, alpha waves are decreased when the eyes are open, as well as by drowsiness and sleep. See Chapters 3 and 12.
5
Q
Amnesia (am-NEE-zhuh)
A
(from Greek a-mn-siadnot memory) A loss of memory. Two types are anterograde (a loss of memory after the time of the brain injury) and retrograde (a loss of memory before the time of the brain injury). See Chapter 7.
6
Q
Amygdala (uh-MIG-da-la)
A
(from amygdala-almond) The amygdalas are two small, almond-shaped masses of neurons located inside the tips of the temporal lobes. They are considered part of the limbic system and play major roles in emotions like fear and trust, as well as in learning. See Chapter 11.
7
Q
Anterior (ann-TEER-ee-er)
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(from ante in front of) Located in front of something. See Chapter 2.
8
Q
Anterior cingulate cortex (an-TEER-ee-er SIN-gyu-lut COR-teks)
A
(from Latin ante before, in front of; Latin cingulum girdle; Latin cortex bark) The frontal part of the cingulate cortex. The anterior cingulate cortex is involved in executive functioning. See Chapter 2.
9
Q
Anterior commissure (an-TEER-ee-er KA-mih-shur)
A
(from Latin ante before, in front of) A large bundle of nerve fibers connecting the two cerebral hemispheres. See Chapter 2.
10
Q
Anterograde amnesia (AN-teh-ro-grayd am-NEE-zhuh)
A
(from New Latin antero-forward; Greek a-mne-sia-not memory) A form of amnesia in which events after the brain injury are not encoded in long-term memory, although events may be recalled from the period before the injury. See Chapter 7. See retrograde amnesia.
11
Q
Aphasia (AY-PHAY-zha)
A
(from, a-without; Latin phasia-speech) A loss of language function due to brain injury, such as damage to Broca’s area, for speech production, or Wernicke’s area, for speech understanding. See Chapter 6.
12
Q
Arcuate fasciculus (AR-cue-ate fa-SIK-u-lus)
A
(Latin for arched bundle) A bundle of axonal fibers, especially the ones connecting Broca’s and Wernicke’s areas in the left hemisphere. See Chapter 2.
13
Q
Area MT
A
A part of the visual cortex that represents visual motion. See Chapter 4.
14
Q
Artificial neural network (ar-ti-FI-shel NOOR-el NET)
A
(from Greek neuron nerve) Also known as ANNs or neural models, artificial neural networks are simulated, simplified models of brain functions. Most are relatively small in scale. However, they are important for understanding the principles of neural computation.
15
Q
Associative process (uh-SO-see-a-tiv PRA-ses)
A
(from Latin ad- þ sociaredto join) A process in which one or more sensory and/or response events are linked in the brain.
16
Q
Attention (a-TEN-shun)
A
(from Latin atten e-re to stretch out) Selection of some sensory, cognitive, or motor events to the exclusion of others. Attention is often taken to involve a focus on certain conscious events. Also see selective attention. See Chapter 8.
17
Q
Attention network task (ANT; a-TEN-shun NET-werk TASK)
A
A generalization of the flanker task, a tool for studying visual attention. The ANT allows testing of three separate aspects of attention: alerting before an expected signal, orienting to a specific location in space where the target is expected, and executive attention to act against expectations set up by the task. See Chapters 8 and 9.
18
Q
Auditory cortex (AW-di-tor-ee kor-teks)
A
(from Latin auditorius pertaining to one who hears; Latin cortex bark) The parts of the cerebral cortex involved in processing sounds, such as Wernicke’s area and Heschl’s gyrus. See Chapter 5.
19
Q
Auditory scene analysis (AW-di-tor-ee SEEN uh-NAL-ih-sus)
A
The process by which the auditory system segments and organizes the listening environment. See Chapter 5.
20
Q
Automatic process (au-to-MA-tic PRAH-ses)
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A highly practiced skill or habit that can be performed with minimal conscious involvement and voluntary effort. See Chapter 7.
21
Q
Autonomic nervous system (ANS; aw-to-NOM-ic NER-vus SIS-tem)
A
(from Greek neuron nerve) The division of the peripheral nervous system that acts to maintain homeostasis and to regulate rest and activity. Physiological activities controlled by the ANS, such as blood pressure and sweating, are generally unconscious and nonvoluntary.
22
Q
Axon (AK-son)
A
A long, slender branch of a nerve cell (neuron) that conducts electrical impulses away from the cell body. See Chapter 2.
23
Q
Baron-Cohen, Simon (b. 1958)
A
Autism researcher who proposed that young children develop a theory of mind capacity composed of four skills: detection of intentions of others, detection of eye direction, shared attention with others, and implicit knowledge about others. See Chapter 10.
24
Q
Basal ganglia (BAY-zel GAN-glee-uh)
A
(from Greek basis step, base; Greek for ganglion ‘tumor on or near tendons’) A large cluster of subcortical structures just outside of each thalamus, involving motor control, automaticity, cognition, emotions, and learning. See Chapter 2.
25
Beta waves (BAY-tuh WAYVZ)
(second letter of Greek alphabet) A band of irregular electromagnetic waveforms detected in the brain or on the scalp, and apparently reflecting the activity of large populations of neurons. The beta band has a frequency above 18e25 Hz and is associated with normal waking consciousness. Low-amplitude beta waves with multiple and varying frequencies often are associated with active, busy, or anxious thinking and active concentration. See Chapter 12.
26
Binocular disparity (bih-NOC-u-ler dis-PAR-eh-tee)
(from Latin bi two; Latin oculus eye; Latin disparar to separate) The difference in perceived location of an object seen by the left and right eyes, resulting from the eyes’ horizontal separation. The brain uses binocular disparity to obtain depth information from the retinal image in both eyes. See Chapter 4.
27
Binocular rivalry (bih-NOC-u-ler RYE-vel-ree)
(from Latin bi two; Latin oculus eye) The alternating perception that occurs when a different pattern is shown to each eye and the brain cannot fuse them into a single, coherent percept. Instead, awareness of each eye’s input appears and disappears for a few seconds. See Chapters 4 and 8.
28
Biological motion (BYE-oh-loj-i-kal MO-shun)
Biological motion refers to motions that a body can make as a set of articulated limbs, trunk, and head. Understanding the social implications of body movements is key to detecting any sign of danger or threat as well as helping understand another person’s intentions, emotions, and state of mind. See Chapter 10.
29
Bistable perception (BYE-STAY-bel per-SEP-shun)
(from Latin b-two) Sensory events that alternate between two perceptual interpretations. See Chapter 4.
30
Blindsight (BLIND-site)
A type of brain damage in which patients can report some visual events with no subjective sense of seeing them due to impairment of the first cortical area of the visual system, area V1.
31
Blood-oxygen-level-dependent (BOLD) activity (BLUD OKS-eh-gen LEV-el dee-PEN-dent ak-TI-vi-tee)
A magnetically induced physical signal that reflects the flow of oxygen in the bloodstream in specific regions of the brain. The BOLD signal is the physical source for functional magnetic resonance imaging (fMRI). See Chapter 3.
32
Brainstem (BRAYN-stem)
The lower part of the brain connecting to the spinal cord. All major motor and sensory systems pass through it, including the optic and auditory nerves. The brainstem also regulates cardiac and respiratory functions and maintains conscious waking, slow-wave sleep (SWS), and rapid eye movement (REM) dreams. See Chapter 2.
33
Broca, Pierre Paul (1824-80)
A French surgeon who studied a brain-damaged patient with expressive aphasia the inability to speak, while being able to understand speech. After the patient’s death he was able to conduct a postmortem identifying the damaged region as the left inferior frontal gyrus, now called Broca’s area. See Chapter 6.
34
Broca’s area (BRO-kas AIR-ee-a)
The left inferior frontal gyrus, or its posterior segment, reported by Pierre Paul Broca in 1861 is responsible for the deficit of a patient who could not speak but had preserved speech understanding. Other functions have since been attributed to Broca’s area. See Chapter 6.
35
Brodmann’s areas (BROD-mans AIR-ee-uh)
About 100 cortical regions defined and numbered by German neurologist Korbinian Brodmann, originally based on the microscopic anatomy of neurons in different patches of the cortex. They are still widely used for cortical localization, and Brodmann’s areas generally have distinctive functions. See Chapter 2.
36
Cell assemblies (SEL uh-SEM-blees)
Also called Hebbian cell assemblies, these are active networks of related neurons representing some sensory input or similar event. According to Donald O. Hebb’s 1949 hypothesis, “neurons that fire together, wire together,” so that simultaneous firing causes the synaptic links in a cell assembly to grow stronger. See Hebbian learning. See Chapter 7.
37
Central executive (CEN-trel eks-EK-yoo-tiv)
(from Latin centrum center) Brain processes for planning, decision making, abstract thinking, rule acquisition, initiating and inhibiting actions, resolving goal conflicts, and flexible control of attention. These functions relate to working memory and tend to involve the frontal lobes. See Chapter 9.
38
Central nervous system (CNS; SEN-trel NER-vus SIS-tem)
(from Latin centrum center; Latin nervus sinew, nerve) The brain and spinal cord. All neurons outside of the CNS are considered to be the peripheral nervous system (PNS). See Chapter 2.
39
Central sulcus (SEN-tral SUL-cus)
(from Latin sulcus groove) Also called the central fissure, this fold in the cerebral cortex is a prominent landmark of the brain that separates the parietal lobe from the frontal lobe and the primary somatosensory cortex from the primary motor cortex. The central sulcus is a clear dividing line between the input- and output-related areas of the cortex. See Chapter 2.
40
Cerebellum (ser-e-BEL-em)
(from the Latin word cerebrum brain, cerebellum means “little brain”) A major region of the brain located just below and to the rear of the occipital lobe of the cerebral cortex. The cerebellum plays an important role in the integration of sensory perception, fine motor control, and sensorimotor coordination. Recent evidence shows cognitive involvement as well. See Chapter 2.
41
Cerebral cortex (suh-REE-bral KOR-teks)
(from Latin cerebrum brain; Greek cortex bark) The outer surface of the great cerebrum, the largest part of the human brain, divided into two symmetrical cerebral hemispheres. Most of the cortex has six distinctive cellular layers, containing cell bodies with a gray appearance. But its long distance nerve cells send out axons to other parts of the cortex, to the thalamus, and to other brain regions, which become covered with white supportive cells (myelin). As a result, a vertical cut of the cortex appears to the naked eye to have a thin, gray outer layer and a white inner mass, called the “gray matter” and “white matter,” respectively. The cerebral cortex plays a key role in sensory analysis, spatial location, speech perception and production, memory, attention, emotion, motivation, action planning, voluntary control, thought, executive functions, and consciousness. See Chapters 2 and 3.
42
Cerebrospinal fluid (CSF; suh-ree-bro-SPEYE-nel floo-id)
(Latin cerebrum brain) The internal circulation of the spine and brain. CSF allows for a protected flow of molecules and cells that is not exposed to the bloodstream. See Chapter 2.
43
Cerebrum (suh-REE-brum)
(Latin for brain) See cerebral cortex.
44
Chunking
A way to make efficient use of short-term memory limitations by condensing large amounts of knowledge into small symbolic units, rules, or regularities called “chunks.” In natural language, nouns can be considered to be chunks because they allow us to refer to large bodies of knowledge by single words. See Chapter 7.
45
Cingulate cortex (SIN-gyu-lut KOR-teks)
(from Latin cingulum belt; Latin cortex bark) A part of the cortex on the medial (inner) surface of each hemisphere. It is involved in executive functions, the resolution of conflicting goals, and emotion. See Chapters 2 and 9.
46
Circadian rhythms (ser-KA-dee-an)
A daily, 24-h rhythmic cycle that is affected by light and darkness and that guides our daily wakefulness and sleep patterns. See Chapter 12.
47
Cognitive neuroscience (KOG-ni-tiv NOOR-oeSIeens)
(from Latin cognoscere to know) An emerging integration of two previously separate fields of science, cognitive psychology and neuroscience. Most research in cognitive neuroscience makes use of psychological methods simultaneous with brain activity recording.
48
Coma (KOh-mah)
A state of deep and prolonged unconsciousness with a lack of response to any stimuli and loss of normal sleep wake patterns. See Chapter 12.
49
Computed tomography (kom-PYOO-ted tom-OG-reh-fee)
(from Latin computare to consider; Greek tomosd slice; Greek graphein writing) Abbreviated as CT. Physiological recordings in which a three-dimensional image of a body structure (such as the brain) is constructed by computer from a series of slice images. See Chapter 3.
50
Confabulation (kon-fab-yoo-LAY-shen)
(from Latin fabula-story) A neurological symptom in which false memories or perceptions are reported with no intention to lie. Confusional state A state following traumatic head injury. A posttraumatic confusional state may last days, months, or years ... or recovery may follow swiftly following transition from a minimally conscious state, to posttraumatic confusional state, to full consciousness. Posttraumatic confusional states include extended periods of wakefulness; however, the patient is clearly confused and disoriented. See Chapter 13.
51
Connectionism (keh-NEK-shun-ism)
(from Latin com- nectere -to bind together) The study of artificial or biologically based neural networks.
52
Connectogram (keh-NEK-oh-gram)
The connectogram was developed as a graphical representation of brain connectivity data studied using connectomics, the discipline for mapping and interpreting fiber connections in the brain. See Chapter 2.
53
Consciousness (KON-shes-ness)
(from Latin con together; scientia knowledge) Awareness, wakefulness. Consciousness implies being sensitive and responsive to the environment, in contrast to being asleep or in a coma.
54
Consolidation hypothesis (kon-SOL-ih-DAY-shun high-POTH-uh-sis)
The process by which new memories are transformed into long-term memory traces. Memories may be stored in the same areas of the brain that support active moment-to-moment functions such as perception and speech control. Consolidation may involve synaptic changes in such brain regions, which make active neuronal connections more efficient. See Chapter 12.
55
Contralateral (KON-tra-LAT-er-el)
(Latin for “against the side”) The opposite side of the body or brain. See Chapters 1, 2, and 4. See ipsilateral.
56
Coronal (keh-RONE-el)
(from Latin corona crown) A crown-shaped vertical slice of the brain that divides it into anterior and posterior halves. See Chapter 2.
57
Corpus callosum (KOR-pus kaleOSeum)
(from Latin corpus body; Latin callosum tough) A massive fiber bridge between the right and left hemispheres, consisting of more than 100 neuronal axons. It appears white when cut because the axons are covered by white myelin cells. See Chapter 2.
58
Cortex (KOR-teks)
See cerebral cortex.
59
Cortical column (KOR-ti-kel KAW-lum)
(from Greek cort-skin, husk; Latin columna-pillar) A barrel-shaped slice of the six surface layers of the cortex that often contain closely related neurons. Columns are about 0.5 mm in diameter and 2.5 mm in depth. They may be clustered into hypercolumns, which may be part of even larger clusters.
60
Cortical core (KOR-ti-kel kor)
An expression referring to the cerebral cortex and the thalamus in the left and right hemispheres. Together, these structures form a massive hub that serves as a core for brain function. See Chapter 2.
61
Cortisol (Kor-ih-sal)
Cortisol is a hormone key to the circadian rhythms, wake and sleep. Secreted by the adrenal glands, cortisol levels begin to increase in the early morning. They increase by about 50% in the first half hour after awakening, triggering signals throughout the brain and body for arousal. This is termed the “cortisol awakening response.” Cortisol levels decrease throughout the day into the evening, reaching their lowest levels between midnight and 4 a.m. during NREM and SWS stages. Cortisol levels increase again in the early morning during REM sleep and as dawn approaches, they ramp up for another day. See Chapter 12.
62
Creole (KRAY-ole)
A true language that children spontaneously evolve in multilingual communities. Creoles often are encountered in island communities where language communities overlap. “Creoles” are contrasted with “pidgins,” which are dialects typically spoken by adults as a second language consisting of simplified phrases rather than full grammatical languages: for example, “me go now” as opposed to “I am going now.” Creoles are remarkable because they exhibit a full-fledged grammar, unlike pidgins. The spontaneity with which they arise suggests that human infants and children may be equipped with a biological language capacity with universal features. Crowding Crowding is the difficulty in recognizing individual objects in clusters of other objects or natural scenes. Note that we stated “recognizing”despite being in a crowded part of your visual field, individual features of that crowded scene are detected. The breakdown comes when they are to be identified as individual objects. See Chapter 4.
63
Declarative memory (deh-KLAR-a-tiv MEM-ree)
(from Latin declararedLatin declarare, from de- ‘thoroughly’ þ clarare ‘make clear.’) The capacity to recall facts and beliefs. A kind of explicit memory. See Chapter 7.
64
Delta waves (DEL-tuh WAYVZ)
(fourth letter of Greek alphabet) A band of slow, high-amplitude electromagnetic waveforms associated with deep sleep and recorded in the brain or on the scalp, apparently reflecting large populations of neurons. Delta generally is considered to be less than 2.5 Hz. It coexists with waking EEG as well but becomes visible in the raw (unprocessed) EEG only when delta predominates in sleep and drowsy states. See Chapter 3.
65
Dendrite (DEN-drite)
(from Greek dendrites ‘treelike’) One of numerous thin, branched micron-level tubes extending from the cell body of a neuron. Dendrites typically receive synaptic stimulation from other neurons, and therefore serve as the input branches of the neuron. See Chapter 2.
66
Descartes, René (1596-1650)
A French philosopher, mathematician, scientist, and writer who spent most of his adult life in the Dutch Republic. Descartes has been dubbed the “Father of Modern Philosophy” and was also a careful student of the brain. He often is considered the originator of modern mind/body philosophy.
67
Developmental cognitive neuroscience (deh-vel-op-MEN-tel COG-ni-tiv NUR-o-si-ens)
The study of the normal growth of the brain and its mental capacities. See Chapter 14.
68
Diencephalons (die-en-SEF-a-lon)
(from Greek dia-through; en kephalos brain) The part of the brain that contains the thalamus, hypothalamus, and the posterior half of the pituitary gland.
69
Diffusion tractography (di-FYOO-zhen trak-TOH-greh-fee)
(from Latin diffusus scatter; traheredto pull; Greek graphein writing) A brain imaging technique that tracks the diffusion of water molecules to trace the major neuronal pathways of the brain. See Chapter 3.
70
Discourse (DIS-kors)
A connected series of utterances, a conversation. Used by linguists to reflect more than a series of sentences, rather a conversation with a theme and with intents. See Chapter 6.
71
Disorder of consciousness
Disorders of consciousness (DOC) are potentially nonreversible unconscious states due to brain trauma or damage. See Chapter 13.
72
Domain specificity (do-MANE spes-i-FIS-ih-tee)
Functional specificity of brain regions or mechanisms. The idea that each cognitive function may have its own region or network of brain regions, rather than general-purpose brain mechanisms with multiple cognitive functions.
73
Dorsal (DOR-sel; from dorsum back)
The upper part of a brain structure, also called superior.
74
Dorsolateral prefrontal cortex (DOR-so-LAT-er-el pree-FRON-tal KOR-teks)
(from Latin dorsum back; latusd side; predin front of; forms the forehead; Greek cortex bark) Prefrontal region involved in motor planning, executive control, self-regulation, emotion, and working memory. See Chapters 2 and 9.
75
Dynamic causal modeling (die-NAM-ic KOS-el MO-del-ing)
(from Greek dynamikos powerful; Latin causad cause; Latin modulus small measure) A method for interpreting brain data, such as fMRI, that helps to interpret causal relationships among brain activities during a specified task.
76
Edelman, Gerald M. (b. 1929, d. 2014)
American immunologist and neurobiologist who won the Nobel Prize for his work on the structure of antibody molecules. Edelman developed the theoretical framework of Neural Darwinism, which applies Darwinian selectionist principles to the brain, in contrast to the instructionist principles of conventional computers.
77
Electroencephalography (EEG;eh-LEK-tro-en-sef-eh- LOG-reh-fee)
(from Greek elektron sunlight; en- D kephale in the head; grapheindwriting) Electrical activity that typically is recorded on the scalp and sometimes on the surface of the cortex, reflecting the electromagnetic field of large numbers of active neurons. See Chapter 3.
78
Empathy (EM-path-ee)
(from Greek empatheias passion) The capability to share one’s feelings and understand another person’s. See Chapter 11.
79
Epigenesis (ep-ih-GEN-eh-sis)
(from Greek epidafter; Greek genesis birth, origin) Non-DNA factors that shape cells during gestation (pregnancy) and after birth. Contrasted with the classical central dogma of molecular biology in which DNA is recoded into transfer RNA, which ends in the production of proteins for the structure and functions of all cells. Epigenesis implies a flow of causality in the opposite direction. For example, numerous physiological and environmental factors can influence whether specific genes (DNA) are expressed or not. DNA is the primary molecule that encodes phenotypes, passing the plan for a species from one generation to the next. But non-DNA factors can influence the activation and silencing of DNA, the on/off switches. See Chapter 14.
80
Episodic memory (ep-i-SOD-ic MEM-ree)
(from Greek episei-os coming in besides) Memory for conscious experiences, especially those that can be explicitly recalled, such as times, places, events, associated emotions, and other contextual knowledge. The formation of new episodic memories requires the medial temporal lobe, especially the hippocampal region in combination with the cerebral cortex. See Chapter 7.
81
Evoked potential (EP; ee-VOKD puh-TEN-shul)
(from Latin evocare to call forth; potential power) Also called event-related potential (ERP). A quite stereotypical electrical voltage pattern obtained from the brain, after averaging a time-locked voltage to a stimulus or other known event. Traditionally, the EP was obtained by averaging the stimulus-locked EEG over numerous trials. Although the exact brain sources of EPs are still debated, they are highly sensitive to cognitive and emotional variables. See Chapter 3.
82
Executive attention (ek-ZEK-u-tiv a-TEN-shun)
Also called voluntary, goal-directed, or top-down attention. The act of voluntarily focusing on one stream of conscious events while ignoring others. Also see selective attention, stimulus-driven attention. See Chapters 8 and 9.
83
Executive function (ek-ZEK-u-tiv FUNK-shun)
Also called executive control or frontal lobe function. Capacities such as planning, cognitive flexibility, voluntary action, abstract thinking, rule acquisition, initiating correct actions and inhibiting incorrect ones, impulse control, and emotional regulation. See Chapter 9. Explicit memory (eks-PLI-sit MEM-ree; from Latin explicitus clear) A type of memory involving conscious, intentional recollection of stored experiences and knowledge. See implicit memory, implicit learning. See Chapter 7.
84
Feedback (FEED-bak)
1. In goal-guided systems, a signal from the environment indicating the degree of error in achieving the goal. 2. In neuroscience and psychology, an environmental signal reflecting some neuronal event. This kind of neurofeedback often allows people to learn to control otherwise spontaneous neuronal activities. 3. In neural networks, a flow of information returning an output signal to the input layer of the network. Some theorists make a strong distinction between feedback and reentrant signaling in the thalamo-cortical system of the brain. See Neural Darwinism. Chapter 7.
85
Feedforward (feed-FOR-werd)
1. Signal passing from a simpler to a more complex stage of processing. 2. In sensorimotor guidance, preparing an internal action trajectory to obtain more precise feedback when the action is executed. This strategy is used in fast movement control in birds and humans, and even in machines like aerodynamically unstable jet planes. 3. In neural networks, passing information from earlier to later layers of the network.
86
Fetal alcohol syndrome (FEE-tel AL-ko-hol SIN-drum) (FAS)
Brain damage in a fetus due to the mother’s alcohol consumption, a major health risk. See Chapter 14.
87
Flanker task (FLANK-er TASK)
A tool for studying visual attention in which the subject is asked to respond as quickly as possible to a target at the center of gaze or one located off-center by a known distance. The target is flanked by distracting stimuli, such as arrows or letters. The flanker task permits quantitative assessment of the subject’s speed and accuracy in shifting attention to an expected or unexpected position of the target. Moving attention in an unexpected direction is taken to require executive attention, since it must override the prepared, expected shift. Flanker tasks generally require subjects to avoid voluntary eye movements, so that any change in accuracy or speed in response to a target can be attributed to implicit shifts of attention.
88
Fourier analysis (FOOR-ee-ay uh-NAL-a-sis)
Named after French mathematician and physicist Joseph Fourier, who showed that any complex function can be decomposed into a finite set of sine and cosine functions. In music, for example, this implies that any complex sound can be decomposed into a set of pure tones (sine waves). Fourier analysis is routinely applied to decompose EEG and other complex brain signals into frequency bands.
89
Frontal lobe (FRON-tal lobe)
A large region of the cortex located at the front of each cerebral hemisphere and positioned forward of the parietal lobes and above and in front of the temporal lobes. The executive functions of the frontal lobes include the ability to anticipate the consequences of actions, to plan and make decisions, to speak, to override inappropriate impulses and resolve conflicting goals, to understand the mental states of others, and to hold information in working memory. See Chapters 2 and 9.
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Functional fixedness (FUNK-shun-el FIKS-ed-ness)
A cognitive set that tends to block a person from novel ways of acting, perceiving, or solving problems. See Chapter 7.
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Functional magnetic resonance imaging (fMRI; FUNK-shun-el mag-NET-ic REZ-nence IH-ma-jing)
fMRI uses a combination of the MRI signal which provides images of the brain with high anatomical accuracy with measures to assess sensory, motor, and cognitive processes. fMRI experiments typically use a subtraction method where brain activation for one experimental condition is literally subtracted from another. Early fMRI studies employed a task þ resting state method where, for example, brain activation for a particular task would be compared for activation during a rest (no task) condition. fMRI methods have continued to change and evolve and currently there are many other methods employed that are more sensitive to providing information about complex cognitive processes. fMRI helped to make cognitive neuroscience possible. See Chapter 3.
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Functional neuroanatomy (FUNK-shun-el NUR-el-an-at-oh-mee)
The study of how the many brain areas contribute to our functional selves: ranging from emotional processing to social cognition, to language and thought, and to attentional processes and future planning. See Chapters 2 and 3.
93
Functional redundancy (FUNK-shun-el ree-DUN-den-see)
Built-in backup functions in a system to prevent the complete failure of critical functions. For example, mammals have two lungs so that if one fails, the organism still has one lung to breathe. The brain has multiple redundant capabilities.
94
Fusiform face area (FFA; FYOO-ze-form)
(from Latin fusus spindle, after its shape) A specialized region in the medial temporal lobe that responds selectively to visual faces compared with other objects. See Chapters 4 and 10. Gage, Phineas (1823e60) A historic brain damage patient, whose railroad accident demonstrated remarkable spared cognitive capacities in spite of severe damage to the frontal lobes. Gage was a railroad foreman who had a two foot long thin tamping iron shot through the upper orbit of the left eye and out through the medial scalp, when an unstable dynamite charge exploded unexpectedly. Although Gage appeared to have no loss of perception, motor control, or speech, his personality changed in ways that have come to typify frontal lobe damage, especially a major loss of impulse control and long-term motivation.
95
Gamma waves (GAM-a WAYVZ)
(third letter of Greek alphabet) A band of fast, low-amplitude electromagnetic waveforms associated with wakefulness and active thinking, and recorded in the brain or on the scalp, apparently reflecting the activities of large populations of neurons. The gamma band is thought to be centered near 40 Hz, ranging from 25 to 60 Hz. However, higher frequency waves are sometimes labeled gamma as well. Gamma is thought to reflect regional connectivity in the service of current tasks. See Chapter 3.
96
Ganglion (GAN-glee-on)
(Greek for ganglion ‘tumor on or near tendons’) A large cluster of neurons. The major subcortical organs may be considered to be ganglia, such as the basal ganglia. They are often very large structures and have multiple functions. They are typically composed of subdivisions, which themselves are often layered and folded arrays of nerve cells.
97
Gestalt (gesh-TALT)
(German for form) 1. A perceptual stimulus that cannot be reduced to simple subcomponents. 2. A branch of psychology based on the German concept of Gestalt, often summed up with the slogan that “The whole is more than the sum of its parts.” Gestalt psychology has profoundly influenced the study of perception. See Chapter 6.
98
Glial cell (GLEE-el SEL)
(from Greek glia glue) Nonneuronal cells in the brain that support neurons, maintain neurochemical homeostasis, form a protective myelin sheath around neurons, and process information. See Chapter 14.
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Global states
Most scientists agree to the existence of three global brain states for humans: waking, sleeping, and dreaming. See Chapter 12.
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Gray matter
The outer layers of the cerebral cortex, as seen with the naked eye. Gray matter contains the cell bodies of tens of billions of neurons that send white-covered axons in many directions below the cortical mantle. See white matter. See Chapter 2.
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Hebbian learning (HEB-ee-en LUR-ning)
According to Donald O. Hebb, “neurons that fire together, wire together.” That is, two neurons strengthen their synaptic links if they are active at the same moment. This process forms cell assemblies. Introduced by Donald Hebb in 1949, it is also called Hebb’s rule. See Chapter 7.
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Hemispheric lateralization (hem-is-FEER-ik lat-er-al-ih-ZAY-shun)
(from Greek hemi- (half) D spherion sphere; and Latin lateralis side) The degree to which certain brain functions are performed primarily by one cerebral hemisphere, the most prominent being speech production on the left side for most people.
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Hemodynamics (HEE-mo-dye-NAM-ics)
(from Greek hema blood; dynamos force or power) The study of blood flow changes, particularly in the brain, as an index of local neural activity. See Chapter 2.
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Hippocampus (hip-o-KAM-pes)
(Greek seahorse, from hippos horse, kampos sea monster) In the human brain, the hippocampi are looped structures in each of the two medial temporal lobes. The hippocampi are part of the limbic system and play basic roles in encoding and retrieving episodic and semantic memories and in spatial navigation. See Chapters 2 and 7.
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Homunculus (ho-MUN-cue-lus)
(Latin little man) The distorted human body maps in the primary somatosensory cortex (the sensory homunculus) and in the primary motor cortex (the motor homunculus). The lips, hands, feet, and sex organs have more sensory neurons than other parts of the body, so the homunculus has correspondingly distorted large lips, hands, feet, and genitals. Each hemisphere contains a sensory and motor homunculus of the opposite side of the body. These body maps were discovered by neurosurgeon Wilder Penfield at the University of Montreal in the 1950s and 1960s.
106
Hypothalamus (hie-po-THAL-a-mus)
(from Latin hypo below; Greek thalamus chamber) The major neuroendocrine organ of each side the brain, with vital roles in the regulation of blood nutrients, motivation, appetite control, and other major life functions. The hypothalamus is located below each thalamus just above the brainstem. It is closely related to the pituitary and pineal glands. See Chapter 2.
107
Immediate memory (ih-MEE-dee-et MEM-er-ee)
Also called short-term memory. The ability to recall something for 10-30 s without rehearsal. Working memory and sensory memories can be seen as specific kinds of immediate memory. See Chapter 7.
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Implicit memory (im-PLI-sit MEM-er-ee)
(from Latin implicit usd obscure) Unconscious memory, which may arise from conscious or unconscious events. See Chapter 7.
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Inattentional blindness (in-uh-TEN-shun-el BLIND-ness)
A reliable experimental phenomenon in which one is not able to see things that are normally clearly visible. See Chapter 8.
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Inference (IN-fer-ens)
Drawing a conclusion based on knowledge rather than direct observation.
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Inferior (in-FEER-ee-er)
(from Latin inferus lower) Below. See Chapter 2. Insomnia Insomnia is by far the most common sleep disorder. People with insomnia can have trouble falling asleep, staying asleep, or waking up too early in the morning. Some instances of insomnia are brief: these are called acute insomnia and can happen because of stress, work demands, or emotional issues. However, when insomnia occurs for at least 3 days a week and lasts more than 3 months, it is called chronic insomnia. While some instance of insomnia occurs for almost half of all people, chronic insomnia is far less typical, occurring in only about 10% of the population. See Chapter 12.
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Insula (IN-soo-la)
(Latin for island) A structure that is hidden in and underneath the lateral sulcus, covered up by the temporal and parietal lobes, and therefore appears as an island when the covering tissues are gently pulled away. The insula is involved in “gut feelings,” such as the sense of nausea and disgust, and possibly in emotional feelings and cravings. See Chapter 2.
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Intentionality (in-ten-shen-AL-ih-tee)
The “aboutness” of mental events, their ability to represent aspects of the world. Distinguished from intention as a mental goal. See Chapter 10.
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Interaural level difference (in-ter-OR-el)
(from Latin inter-between; aurisdear) A method of sound localization in which the brain detects the small difference in loudness between the two ears that occurs when a sound travels toward the head from an angle. See Chapter 5.
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Interaural time difference (in-ter-OR-el)
A method of sound localization in which the brain detects the split-second delay between the time when sound from a lateral source reaches the near ear and when it reaches the far ear. See Chapter 5.
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Intonation contour (in-toh-NAY-shun kon-TOOR)
The “melody” or singsong of normal speech. In English and other languages, questions typically are given a different intonation contour (a rising tone) compared with affirmative statements (a falling tone).
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Ipsilateral (IP-si-LAT-er-al)
(from Latin ipse self; lantus side) On the same side of the body. See contralateral. See Chapter 2.
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Lateral (LAT-er-al)
(from Latin lateralis side) On the side(s) of the brain. See Chapter 2.
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Lateral geniculate nucleus (LGN; LAT-er-el jen-IK-yoo-let NOO-klee-us)
(from Latin latus side; genu knee shaped; Latin nux nut) A nucleus consisting of “knee-shaped” layers of cells in the thalamus. It is the primary relay center between the retina of the eye and the primary visual cortex (Area V1). See Chapter 2.
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Lateral inhibition (LAT-er-el in-hi-BI-shun)
(from Latin latus side; Latin inhibitusdrestrain) The capacity of a neuron to reduce the activity of its neighboring cells in the same layer of neurons. See Chapter 4.
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Lateral occipital complex (LOC; LAT-er-el ox-SIP-it-al KOM-pleks)
(from Latin latus side; Latin occiput rearmost part of the skull) A region on the side of the occipital lobe that has a general role in visual object recognition. See Chapter 4.
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Lateral sulcus (LAT-er-al SUL-cus)
(from Latin latus side; sulcus groove) Also called Sylvian fissure or lateral fissure. This prominent “valley” divides the temporal lobe from the frontal and parietal lobes. See Chapter 2.
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Lexical identification (LEKS-ih-kul eye-den-tih-fih-KAY-shun)
(from Greek lexis word) The process of assigning words to speech sounds. See Chapter 6.
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Lexicon (LEKS-ih-con)
(from Greek lexis word) The vocabulary of a language.
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Limbic system (LIM-bik sis-tem)
(from Latin limbus border) A set of brain structures involved in emotion, memory, olfaction, and action control, including the hippocampus, amygdala, thalamus, hypothalamus, and cingulate gyrus. The limbic system is interwoven with the endocrine system and autonomic nervous system. See Chapter 11.
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Locked-in syndrome
Although discussed in depth in Chapter 13, Disorders of Consciousness (DOC), locked-in (LI) syndrome is not a DOC. An LI patient typically has brain damage; however, it is limited to the brainstem region and the cortex is largely unaffected. So, although they may present as similar to a patient in a vegetative state (VS) without the ability to move or speak, the LI patient actually has an intact cortex and preserved cognition. See Chapter 13.
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Long-term depression (LTD; LONG TERM de-PRE-shun)
(from Latin deprimerad to press down) A lasting decrease in the strength of a synapse. Along with long-term potentiation (LTP), LTD is thought to be a synaptic basis for learning and long-term memory.
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Long-term potentiation (LTP; LONG TERM puh-ten-shee-AY-shun)
(from Latin potential power) A long-lasting strengthening of a synaptic link. Along with LTD, LTP is thought to be the synaptic basis of learning and long-term memory.
129
Longitudinal fissure (lon-gi-TOOD-in-al FISH-er)
(from Latin fissus crack, opening) The deep valley that divides the right and left hemispheres of the vertebrate brain. See Chapter 2.
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Magnetic resonance imaging (MRI; mag-NET-ik REZ-nence IH-ma-jing)
(Latin resonare to sound; imago imitation) Based on the spin resonance of atomic nuclei, MRI is a technique used to visualize the internal structures of the body, including the brain. Functional MRI (fMRI) records brain activity and is often superimposed on the structural brain image obtained via MRI. See Chapter 3.
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Magnetoencephalography (MEG; mag-NET-o-en-sef-eh-LOG-gra-fee)
(Greek en- D kephale-in the head; grapheindwriting) An imaging technique based on the magnetic fields produced by brain activity. MEG is silent and noninvasive and has good temporal and spatial resolution. See Chapter 3.
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Medial (MEE-dee-al)
Toward the midline of the body or the brain. midsagittal. See Chapter 2.
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Medial temporal lobe (MTL; MEE-dee-el TEM-per-el LOBE)
The bottom aspect of the temporal lobes, which are arranged symmetrically around the midline and contain evolutionarily ancient olfactory structures, memory encoding and recall, and emotional functions. See Chapters 2 and 7.
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Memory (MEM-ree, MEM-eh-ree)
(from Latin memordmindful) A lasting brain representation that is reflected in thinking, experience, or behavior. See Chapter 7.
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Mental flexibility (MEN-tel fleks-ih-BIL-ih-tee)
(from Latin mensa mind; Latin flexusdbent; Latin -ibilis, from -bilisdcapable or worthy of) Also called ability to shift cognitive set. The capacity to respond rapidly to unanticipated environmental contingencies. See Chapter 7.
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Mentalize (MEN-tel-ize)
(from Latin mensa mind) The ability to understand the self and others, not just as sensory objects but also as subjective beings with mental states. See Chapter 11.
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Metacognition (MET-a-cog-NI-shen)
(from Greek metadabove; Latin cognere to know) Knowing about cognition awareness and understanding of one’s own thought processes. !Midsagittal (mid-SAJ-i-tal)
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Mind
(from Greek menos spirit) Those aspects of intellect and consciousness manifested in thought, perception, memory, emotion, will, and imagination, including all of the brain’s conscious and unconscious cognitive processes.
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Minimally conscious state
A minimally conscious state (MCS) differs sharply from a VS patient (see vegetative state). While an MCS includes eye opening as in VS, that wakefulness sign is coupled with some receptive and expressive language function, some command-following behavior, visual pursuit of a moving object, and some automatic motor movement sequences. There are some inconsistent but clear signs of self-awareness in an MCS patient. Some patients in an MCS may respond emotionally to family faces or photographs; they may smile or cry. They may make purposeful movements, for example, reaching for a glass; however, the MCS is characterized by inconsistency in these behaviors. MCS is thought of as a transitional state, that is, a state a patient travels through during recovery of consciousness with healing or decline with neurodegeneration. See Chapter 13.
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Morpheme (MOR-feem)
(from Greek morphed form) The smallest linguistic unit that can convey meaningful information by itself. In English, prefixes and suffixes are considered to be morphemes (e.g., “pre-” and “post-”) as well as the single phoneme/s/, which can signify the plural. See Chapter 5.
141
Motion blindness (MO-shun BLIND-nes)
A symptom caused by injury to brain regions needed for motion perception, such as area MT of the visual cortex, resulting in an inability to perceive visual motion. See Chapter 4.
142
Multistable perception (MUL-tee-STAY-bel per-SEP-shun)
from Latin stabilis, from the base of stare ‘to stand.’ Alternating visual perceptions of an ambiguous stimulus. See bistable perception and Chapter 4.
143
Myelin (MY-e-lin)
(from Latin myeldmarrow) A sheath of glial cells, called the myelin sheath, surrounding the axons of many neurons. Myelinated axons appear white, hence the “white matter” of the visible brain. See Chapters 2 and 3.
144
Narcolepsy (NAR-ko-lep-see)
Narcolepsy is a rare REM-centered sleep disorder of largely unknown origin. It typically occurs in adolescents and young adults but is sometimes not accurately diagnosed until years later. There are five central symptoms that together form a likely diagnosis of narcolepsy, but the foremost symptom of narcolepsy is that the patient suddenly falls asleep. The core symptoms associated with this are persistent daytime sleepiness, hallucinations, sleep paralysis, cataplexy, and restless sleep during the nighttime. See Chapter 12.
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Neocortex (NEE-o-COR-tex)
(from Latin neodnew; Greek cortdbark) The largest and most visible part of the human cerebral cortex. It is the “new” cortex from an evolutionary point of view, as contrasted with the “old” cortex of the medial temporal lobe, hippocampus, and olfactory brain. See Chapter 2.
146
Neon color spreading (NEE-on CAW-ler SPRED-ing)
A perceptual illusion in which white space appears to be tinted by proximity to colored and black lines. See Chapter 4.
147
Neural Darwinism (NUR-el DAR-win-izm)
(from Greek neuron nerve) A theory proposed by physician and neuroscientist Gerald Edelman that suggests that neurons develop and make connections following Darwinian principles. In biological evolution, species adapt by reproduction, mutations leading to diverse forms, and selection among the resulting repertoire of slightly different organisms. Neural Darwinism suggests that brains develop in similar fashion, both in the reproduction, variation, and selection of developing neurons, and in a later stage, in the Darwinian selection of synaptic connections. Brains are said to be selectionist rather than instructionist, unlike the program of a digital computer.
148
Neural migration (NUR-el my-GRAY-shun)
(from Greek neuron nerve) Movement of nerve cells from their place of origin toward their final location in the developing brain. See Chapter 14.
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Neural net model (NUR-el NET MO-del)
(from Greek neuron nerve) Also known as artificial neural networks (ANNs), neural models are simulated, simplified models of selected brain functions. Most are relatively small in scale and do not represent the great complexity of the brain. However, they are important for a better understanding of how neural computation might work.
150
Neuroanatomy (NOOR-oh-an-at-oh-mee)
The study of the structures and regions of the brain. See Chapter 2.
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Neuroconnectivity (NOOR-oh-con-ekt-iv-ih-tee)
The study of the connected pathways of the brain. See Chapter 2.
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Neurodynamics (NOOR-oh-die-nam-ikz)
The study of the neural transmission and oscillations in the brain. See Chapter 2.
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Neuromodulator (NOOR-o-MOD-u-lay-ter)
(from Greek neuron nerve; modulate is used in the sense of “influence” or “regulate”) Certain neurochemicals have very widespread effects in large regions of the brain. These are called neuromodulators, whereas neurotransmitters are molecules with very local effects in specific synapses. See Chapter 12.
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Neuron (NOOR-on or NYOO-ron)
(from Greek neuron nerve) Nerve cells that transmit information by electrochemical signaling. They are the core components of the human brain, spinal cord, and peripheral nerves. Many different types of neurons exist, from sensory receptors and motor units and neuroendocrine cells to pyramidal neurons, which have long-distance axons; interneurons, which form bushy local connections; and a wide variety of specialized cells. See Chapter 2.
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Neuron doctrine (NOOR-on or NYOO-ron DOK-trin)
(from Greek neuron nerve; doctor teacher) The central theory of the neuron doctrine was a theory credited to the Spanish histologist Santiago Ramon y Cajal, stating that “the nervous system consists of numerous nerve units (neurons), anatomically and genetically independent.” This has been one of the basic assumptions of brain science for the past century. However, the discovery of large numbers of electrical synapses (gap junctions) may challenge some aspects of the neuron doctrine.
156
Neurophysiology (NOOR-oh-fiz-ee-ol-oh-gee)
The study of the cellular properties in the brain. See Chapter 2.
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Neurotransmission (NOOT-oh-trans-MISH-en)
Electrochemical signaling between nerve cells. See Chapter 3.
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Neurotransmitter (NOOR-o-TRANS-mit-er)
(from Greek neuron nerve; Latin trans moving through) Chemicals that act to relay a signal from one neuron to the next across a synaptic cleft. Some neurotransmitters are packaged into vesicles that cluster beneath the membrane on the presynaptic side of a synapse and are released into the synaptic cleft, where they bind to receptors located on the postsynaptic membrane. Release of neurotransmitters often is driven by action potentials in the presynaptic axon. There is a low level of baseline release even in the absence of an action potential. See Chapter 2.
159
Nonrapid eye movement sleep
Sleep falls into two general patterns: nonrapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM sleep is described as occurring during sleep stages IeIV. It is characterized by slowed brain functions and slow waves as measured by the electroencephalogram. See Chapter 12.
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Object permanence (OB-jekt PER-ma-nens)
The knowledge that perceptual objects continue to exist even when they cannot be seen or touched. Object permanence begins in infants around 7 months. See Chapter 14.
161
Occipital lobe (ox-SIP-it-al lowb)
(from Latin occiput back bone of the skull) The occipital lobes, which contain the earliest visual region of the cortex, are the smallest of four lobes in the human cerebral cortex. See Chapter 2.
162
Orbitofrontal cortex (or-bit-oh-FRON-tel COR-teks)
(from Latin orbis circle, orb, orbit, world) Refers to the part of the brain immediately above the sockets or orbits of the two eyes. See Chapters 2 and 11.
163
Output functions (OWT-put FUNK-shuns)
Brain processes controlled by the frontal lobes that include the central executive, action planning, and motor output. See Chapter 2.
164
Parahippocampal place area (PAIR-a-HIP-o-KAMP-el [PPA])
(from Greek parade before; see hippocampus [PPA]) A region near the hippocampus that responds more strongly to landscapes and visual scenes than to isolated objects such as houses or faces. See Chapter 4.
165
Parietal lobe (puh-REYE-uh-tl lowb)
(from Latin parietalis relating to walls) A large cortical region located above the occipital lobe and behind the frontal lobe. The parietal lobe integrates sensory information from different modalities and contains constantly updated maps of the position of the body and nearby objects. See Chapter 2.
166
Penfield, Wilder (1891-1976)
A neurosurgeon and researcher in Montreal who performed pioneering work in epileptic surgery. Before operating, he performed exploratory brain stimulation in awake patients (who were free of pain using only a local anesthetic in the surgical opening). Thus patients could report their experiences upon electrical brain stimulation. Penfield and coworkers were able to determine functions of the human brain that were previously only approachable via postmortem studies of brain-damaged patients.
167
Perceptual filling in (per-SEP-choo-el FIL-ing in)
A general feature of sensory perception in which the brain fills in missing parts of a visual object or scene, often far beyond the direct sensory input. See Chapter 4.
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Perceptual memory (per-SEP-choo-el MEM-ree, MEM-eh-ree)
(from Latin memordmindful) Long-lasting changes in one’s ability to perceive the world for example, the ability to perceive the sounds of speech and to recognize visual objects under changes in orientation and lighting.
169
Peripheral nervous system (PNS; per-IF-er-el NUHR-vus SIS-tem)
The extensive network of neurons outside of the brain and spinal cord. The PNS includes sensorimotor neurons below the neck and autonomic neurons that innervate the smooth musculature of the digestive tract, heart, and circulatory system. See Chapter 2.
170
Perseveration (per-sev-er-AY-shun)
(from Latin perseverare persist) A symptom involving the inappropriate and uncontrollable repetition of a specific word, phrase, or gesture.
171
Phoneme (FO-neem)
(from Greek phone sound) In human languages, the smallest lexically distinctive category of sound, such as consonants and vowels. See Chapter 5.
172
Planum temporale (PLAH-num tem-por-AHL-eh)
(from Latin planada flat surface; Latin temporalis of the temple) A part of the auditory cortex involved in sound analysis and particularly speech perception. Recently, the posterior portion of the planum temporale has been implicated in sensorimotor processing. See Chapter 5.
173
Plasticity (plas-TI-SI-tee)
(from Greek plastikos, from plassein to mold, form) The ability of the brain to adapt and reorganize to new environmental inputs or demands or following brain damage. See Chapter 14.
174
Polysomnography (POL-ee-som-nog-raf-ee)
Electroencephalography (EEG) is combined with an assortment of eye, muscle, and heart measures using a technique termed polysomnography. The recordings produced using polysomnography; the polysomnogram are used to diagnose sleep disorders such as sleep apnea, narcolepsy, and insomnia. See Chapter 12.
175
Pons (PONZ; Latin, pons bridge)
A prominent anterior bulge in the brainstem. The pons relays sensory information between the cerebellum and the forebrain and spinal cord, helps to control sleep and wakefulness, and regulates respiration among other functions. It also generates REM sleep signals that are interpreted by the cortex as visually vivid, narrative dreams. See Chapter 2.
176
Positron emission tomography (PET; POH-zi-tron ee-MISH-en tom-OG-reh-fee)
(Latin emitter to send out; Greek tomos section; Greek graphein writing) Positrons are positively charged subnuclear particles, typically produced by a particle accelerator. PET is a low-level radioactive imaging technique that allows the computational extraction of brain or body slice maps, from which a three-dimensional image can be constructed. Typically, PET reflects metabolic activity. See Chapter 3.
177
Postcentral gyrus (post-SEN-tral JEYE-res)
(from Latin post behind; Latin gyrusdridge) A protruding fold in the parietal lobe of the human brain immediately behind the central sulcus. It includes the primary somatosensory cortex, the first cortical map of the body senses, also called the sensory homunculus, which represents the opposite or contralateral side of the body. See Chapter 2.
178
Posterior (pos-TEER-ee-er)
(from Latin post after) Behind. In brain anatomy, posterior is synonymous with caudal.
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Precuneus (pree-KUN-ee-us)
A region at the superior aspect of the parietal lobe. In a healthy brain during normal waking, the precuneus is the most highly active (metabolically) regions in the brain. See Chapter 13.
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Prefrontal cortex (pree-FRON-tal KOR-teks)
(from Latin prae in front of; forms the forehead; Greek cortdbark) The large, forward portion of the frontal lobes, not including the motor cortex. Prefrontal cortex includes executive functions and Broca’s area, and is sometimes called “the organ of civilization.” See Chapters 2 and 9.
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Primary motor cortex (PRIE-mar-ee MO-ter KOR-teks)
(from Latin primus first; Greek cortdbark) The brain region that directly controls skeletal (voluntary) muscles. It corresponds to the motor homunculus and works in close association with other sensory body and motor maps, such as the premotor cortex. See Chapter 2.
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Primary somato Sensory cortex (PRIE-mar-ee so-MAT-o-SENS-ery KOR-tex)
(from Latin primus first, most important; soma body; sensus sense; Greek cortdbark) The sensory homunculus (body map), located on the postcentral gyrus of the cortex, is the first cortical area for the body senses of touch, pressure, and pain. See Chapter 2.
183
Primary visual cortex (PRIE-mar-ee VIZH-oo-el KOR-teks)
(from Latin primus first, most important; Latin visusdsight; Greek cortdbark) (also called V1) The first cortical map of the visual system, located within the calcarine sulcus in the occipital lobe. See Chapter 4.
184
Problem space (PROB-lem SPAYS)
A graph of the decision points in problem-solving, often in the form of a tree structure. See Chapter 7.
185
Procedural memory (pruh-SEE-der-el MEM-ree, MEM-eh-ree)
(from Latin procedereda way of doing things; Latin memordmindful) A form of implicit memory equivalent to skill memory (such as riding a bicycle) or knowing how to do a task. It appears to be largely unconscious. This type of memory is often very durable. See Chapter 7.
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Radial unit model (RAY-dee-el YOO-nit MAH-del)
A model of neural migration proposed by neuroscientist Pasko Rakic that asserts that in the developing cerebral cortex, the cells are created at the base of each cortical column and each new cell migrates past its predecessors. See Chapter 14.
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Rakic, Pasko (b. 1933) (rah-KEECH)
A neuroanatomist who showed that neural migration occurs radially as well as rostrally, like the outflowing spokes of a forward-moving wheel. See Chapter 14.
188
Rapid eye movement sleep
Rapid eye movement (REM) sleep involves a major shifting of brain processes from nonrapid eye movement sleep, as can be seen in the changing EEG to a pattern that is similar to an awake state. Most dreaming occurs during REM sleep. Another major change occurs in the body during REM sleep: the body enters a state of atonia or paralysis. Atonia is perfectly normal, and it is thought to be a protection from a person acting out a dream during REM sleep. You may try to movedand in fact many dreams involve a feeling of slow motion or actual paralysis, reflecting the true state of the body even though in our REM dreams we move about freely. See Chapter 12.
189
Receptive field (ree-SEP-tiv FEELD)
(from Latin recipere to take) The receptive field of a nerve cell in the visual system, for example, is the region of the visual field that can activate or inhibit the firing of the cell. The receptive field of a retinal receptor is therefore different from the receptive field of a higher level cell tuned to detect motion or visual object identity. Analogous receptive fields have been found for visual attention in the parietal lobe. Receptive fields are found in other sensory systems as well, such as the auditory and somatosensory systems. See Chapter 2, and see Chapter 4 for more discussion on receptive fields in the visual system.
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Reentrant connectivity (ree-EN-trent con-ec-TIV-e-tee)
Most brain connections are bidirectional, in that activity at point A triggers activity at point B and vice versa.
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Reentry (ree-entry)
In Neural Darwinism, the resonant looping between two neurons or arrays of neurons so that neuron A activates neuron B and vice versa. Reentry can also take place between neuronal populations. It is believed to be the primary signaling mechanism among brain regions and therefore closely related to brain rhythms.
192
Reflex circuit (REE-fleks SIR-kut)
Also called a reflex arc, this is the relatively simple pathway that mediates a reflex action. The most common example is the knee-jerk (or patellar tendon) spinal reflex, which occurs even when the spinal cord is isolated from the brain. However, spinal reflexes can be quite fast, complex, and coordinated, and may interact with the brainstem and the vestibular (balance) system, as in the case of a cat reorienting its body during a fall. Normally reflexes work in close coordination with voluntary control via the frontal lobes,cerebellum, and basal ganglia. Cranial reflexes like the pupillary reflex are under the joint control of autonomic, visual, and emotional regions of the brain.
193
Reticular formation (reh-TIC-u-ler for-MAY-shun)
(from Latin reticulum network) A part of the brainstem that is involved in the sleep waking cycle and many other functions. It receives collateral input from all sensory and motor systems, as well as from higher-level brain structures. It is evolutionarily one of the oldest parts of the brain. See Chapter 2.
194
Retina (REH-tin-a)
The array of light receptors lining the inner surface of the eye. Light striking retinal receptors (rods or cones) trigger a chemical reaction that evokes a change in electrical potential across the cell membrane. This may trigger activity in retinal ganglion cells that project their axons to make up the optic nerve, which terminates in the visual relay nucleus of the thalamus. See Chapter 4.
195
Retrograde amnesia (RET-ro-grayd am-NEE-zhuh)
(from Latin retrograde usd going back; Greek a-mne-sia without memory) A form of memory loss extending before the time of brain injury. Contrasted with anterograde amnesia. See Chapter 7.
196
Sagittal (SAJ-i-tal; from Latin sagitta arrow)
Any section of the brain that runs parallel to the medial or midline cut. See Chapter 2.
197
Selective attention (suh-LEC-tiv a-TEN-shun)
The ability to pay attention to one aspect of the environment while ignoring competing stimuli. This may occur voluntarily, as in choosing to read an interesting book while sitting on a noisy bus, or when one sensory experience is biologically or personally significant. See Chapters 8 and 9.
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Semantic memory (seh-MAN-tic MEM-ree or MEM-er-ee)
A type of declarative memory that involves meanings, factual beliefs, categories, and other general knowledge going beyond specific experiences. See Chapter 7.
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Semantics (seh-MAN-tiks)
The study of meaning in language. See Chapter 7.
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Sensory system (SEN-suh-ree SIS-tem)
Part of the nervous system responsible for processing sensory information (the primary five senses being visual, auditory, tactile, taste, and olfaction [smell]). A sensory system consists of sensory receptors, neural pathways, and mostly posterior cortex involved in sensory perception. The classical senses have many subsenses, such as pain and even tickle sensations, light receptors in the eye that trigger melatonin as a sleep hormone, the balance sense, and the like. Not all sensory systems yield conscious experiences; blood pressure, for example, which is sensed by hypothalamic neurons, is rarely conscious. The classical senses begin with receptor surfaces containing many millions of receptors, such as the retina and the basilar membrane.
