NEUR200 Exam 2 Terms

Presynaptic neuron

Neuron that sends the signal; releases neurotransmitter from its axon terminal

Postsynaptic neuron

Neuron that receives the signal via receptors on its membrane

Synaptic delay

Extra conduction time at synapses, identified by Sherrington from reflex arc studies

Graded potential

Variable-size potential that can be a depolarization (excitatory) or hyperpolarization (inhibitory)

EPSP

Excitatory postsynaptic potential: graded depolarization from Na+ entry; more likely to fire

IPSP

Inhibitory postsynaptic potential: graded hyperpolarization from K+ exit or Cl- entry; less likely to fire

Spatial summation

Inputs from separate locations combine their effects

Temporal summation

Repeated inputs in a brief time have a cumulative effect

Spontaneous firing rate

Action potentials produced even without synaptic input; EPSPs raise it, IPSPs lower it

Neural synchronization

Brain waves from different regions synchronize; supports network communication and oscillations

Exocytosis

Vesicles fuse with the presynaptic membrane and release neurotransmitter, triggered by Ca2+ entry

Ionotropic receptor

Receptor that is an ion channel; fast (

Metabotropic receptor

Receptor that starts a metabolic reaction via second messenger; slower (30 ms+), longer lasting (pain, attention, emotion)

Second messenger

Intracellular signal that spreads a metabotropic receptor's effect inside the cell

Monoamines

Modified amino acid transmitters: dopamine, serotonin, norepinephrine

Mesocortical pathway

Dopamine pathway: VTA

Mesolimbic pathway

Dopamine reward pathway: VTA

Nigrostriatal pathway

Dopamine pathway: substantia nigra

Tuberoinfundibular pathway

Dopamine pathway: hypothalamus arcuate nucleus

Locus coeruleus

Main norepinephrine source in the brain; hindbrain

Raphe nuclei

Main serotonin source; sleep/wake and mood

Norepinephrine

Noradrenaline; alpha and beta receptors; energy, arousal, mood; adrenal gland in PNS

Serotonin

Sleep/wakefulness and mood; highest when awake; SSRIs, TCAs, MAOIs

Glutamate

Main excitatory transmitter; AMPA and NMDA receptors; excitotoxicity

GABA

Main inhibitory transmitter; Cl- influx; GABA-A/B/C receptors; benzodiazepines

Acetylcholine

Nicotinic and muscarinic receptors; muscles, memory, attention; low in Alzheimer's

Nucleus basalis of Meynert

Source of acetylcholine linked to memory and attention (Alzheimer's)

Proliferation

Production of new cells (through about 28 weeks of gestation)

Megalencephaly

Enlarged brain from overproliferation

Microencephaly

Small brain from reduced proliferation

Migration

Neurons guided by chemicals to their destinations

Differentiation

Cell becomes a specialized neuron; axons form first, then dendrites

Myelination

Insulating myelin forms gradually through adolescence and adulthood

Synaptogenesis

Neurons form new synapses and discard old ones; slows with age

Synaptic pruning

Elimination of synapses; too much is associated with schizophrenia

Hindbrain

Medulla, pons, cerebellum; postural support

Medulla

Hindbrain nuclei regulating breathing and heart rate

Cerebellum

'Little brain'; crucial for motor coordination

Midbrain

Spontaneous behavior; superior/inferior colliculi, VTA, SN

Superior colliculus

Midbrain structure for vision and orienting; part of tectopulvinar pathway

Inferior colliculus

Midbrain structure for hearing

Thalamus

Switchbox/relay that directs sensory information to cortex

Hypothalamus

Motivated behaviors (sleep, eating, sex) and thermoregulation

Pituitary gland

Releases hormones

Basal ganglia

Caudate, putamen, globus pallidus (+ SN); self-maintenance, automatic movement sequences

Limbic system

Hippocampus, cingulate gyrus, olfactory bulb, amygdala; emotion, learning, memory

Layer IV

Cortical input zone; large in sensory cortex

Layers V and VI

Cortical output zone; large layer V in motor cortex

Cortical column

Vertical module of functionally similar neurons; apparent in primary sensory areas

Transduction

Conversion of energy (e.g., light) into electrical energy by receptors

Fovea

Retinal area specialized for acute, detailed vision; mostly cones

Rods

Peripheral retinal receptors with better sensitivity to dim light

Cones

Retinal receptors concentrated in the fovea

Geniculostriate pathway

Retina -> LGN -> V1; pattern, color, motion recognition

Tectopulvinar pathway

Retina -> superior colliculus -> pulvinar -> parietal; spatial location, unconscious

Lateral geniculate nucleus (LGN)

Thalamic relay for visual information to V1

Pulvinar nucleus

Thalamic nucleus in the tectopulvinar pathway

V1 (striate cortex)

Primary visual cortex; orientation-selective cells (Hubel and Wiesel)

V4

Visual area important for color

V5 / MT

Visual area important for motion

Ventral stream

'What' pathway to temporal cortex; object identity

Dorsal stream

'Where/how' pathway to parietal cortex; location and action

Fusiform face area (FFA)

Face analysis; left fusiform also important for words

Extrastriate body area (EBA)

Body analysis

Superior temporal sulcus (STS)

Biological motion (body movement)

Parahippocampal place area (PPA)

Scenes (indoor/outdoor places, landmarks)

Parietal reach region

Visually guided reaching (dorsal stream)

Hemianopia

Blindness of half the visual field from damage to the opposite V1

Blindsight

Responding to stimuli not consciously seen after V1 damage

Cortical color blindness

Loss of color cognition from V4 damage

Visual agnosia

Inability to recognize visual information (geniculostriate and ventral pathways)

Apperceptive agnosia

Cannot develop a percept; cannot copy an object

Associative agnosia

Can perceive/copy an object but cannot recognize it

Prosopagnosia

Face blindness; bilateral fusiform damage (right more important)

Alexia

Word blindness; left fusiform damage; can read letter by letter

Simultagnosia

Perceiving only one object at a time; dorsal stream/Balint's syndrome

Neglect

Dorsal stream (parietal) disorder of spatial attention