CNS/PNS Flashcards
Basic neuroscience anatomy
Sensory neurons
afferent; from sensory receptors to CNS
Motor neurons
efferent; from CNS to muscle
Interneurons
most numerous; predominantly located in CNS and are linked to reflexive behavior
Reflex arcs
neural circuits controlling reflexive behavior
PNS division
PNS –> somatic and ANS
ANS –> sympathetic/parasympathetic
ANS
regulates heartbeat, respiration, digestion, & glandular secretions; involuntary muscular activity (mainly associated with internal organs and glands)
ANS subdivision
sympathetic/parasympathetic; often act antagonistically
Parasympathetic NS
conserves energy; associated with resting/sleeping; manages digestion; ACh
Sympathetic NS
stress –> “fight or flight”
Heart rate increases, blood-sugar level and respiration increase, digestion decreases, eyes dilate; EPI (adrenaline) released to increase energy
phylogeny
evolutionary development
H. M.
Famous patient, hippocampus removed to control epileptic seizures; suffered from anterograde amnesia (couldn’t form new long-term memories)
Retrograde amnesia
Memory loss of events that transpired before brain injury
Association vs. projection areas
Association: combines input from diverse brain regions; ex. Planning or decision-making
Projection: receive sensory information or send out motor-impulse commands; ex. Motor cortex or visual cortex
Striate cortex
Visual cortex appears striped under microscope
Ipsilateral communication
Olfactory system communicates within same side of body and hemisphere rather than contralaterally
Hemisphere dominance
97% estimated left hemisphere dominant
Dominant side plays more prominent side in language (B’s and W’s areas associated with dominant hemisphere)
Roger Sperry and Michael Gazzaniga
Studied effects of severing corpus callosum
Glial cells
Nonneural cells of the nervous system; insulate axon with myelin sheath for faster conduction
Dendrites versus axons
Dendrites’ branching patterns can change significantly whereas axons tend to remain contestant throughout aging
Hindbrain (structures)
Cerebellum, Medulla, Reticular formation
Midbrain (structures)
Inferior and superior colliculi
Forebrain (structures)
Cerebral cortex, basal ganglia, limbic system, thalamus, hypothalamus
Medulla
lower structure, regulates vital functions (breathing, heartbeat, blood pressure)
Pons
above medulla, contains sensory and motor tracts between cortex and medulla
cerebellum
Posture/balance, coordinated body movements
Damage to cerebellum –> clumsiness, slurred speech, loss of balance
Reticular Formation
extends from hindbrain into midbrain; composed to intricate network of nerve fibers
Regulates arousal and alertness (sleeping and waking); anesthetics depress activity of RF
Midbrain (Function)
associated with involuntary reflex responses triggered by visual/auditory stimuli
Superior colliculus
Receives visual sensory input
Inferior Colliculus
Receives auditory sensory input; reflex reactions to sudden noises
Thalamus
Relay station for incoming sensory information (all but smell); sensory switchboard (receives sensory information, “sorts” it, then sends it to appropriate area of cortex)
Lateral, Ventromedial, and Anterior Hypothalamus
Homeostatic functions; key in emotional experience during high arousal states, aggressive behavior, and sexual behavior
Drive behaviors: hunger, thirst, sexual behavior
Also related to controlling endocrine functions, as well as ANS
Homeostatic Regulation of Hypothalamus
self-regulatory processes regulating metabolism, temp, and water balance; hypothalamus detects imbalance & sends signal to correct it
Osmoregulation performed by osmoreceptors in hypothalamus
Walter Cannon
developed conceptualization of homeostasis
Lateral Hypothalamus (LH)
“Hunger center” helps body detect when more food/fluids are needed; damage to LH results in aphagia (refusal to eat/drink, rats starve to death if not force fed)
LH also related to rage & aggressive fighting
Ventromedial Hypothalamus (VMH)
“Satiety center”; brain lesion in this area may lead to obesity due to hyperphagia (excessive eating)
Hypothalamus and arousal
manages sympathetic activation (fight/flight); also induces rage that may be inhibited by prefrontal cortex (kitties exhibited spontaneous/non-directed rage when cortex was removed but hypothalamus left intact)
Anterior Hypothalamus
Stimulates seual behavior (esp. aggressive sexual behavior); lesion –> inhibition of sexual activity
Four F’s in Functioning of Hypothalamus
Feeding, fighting, fleeing, fucking
Basal Ganglia
coordinates muscle movement; receives info from cortex and relays to brain and spinal cord via extrapyramidal motor system
Related to Parkinson’s and schizophrenia
Extrapyramidal Motor System
gathers information about body position/proprioception in basal ganglia and carries the information to brain/spinal cord making movement smooth and steady
Parkinson’s disease
associated with substantia nigra in basal ganglia
Ventricles
fluid-filled cavities in the middle of the brain that link up with the spinal canal that runs down the middle spinal cord; filled with same cerebrospinal fluid
Enlarged ventricles have been linked with schizophrenia
Limbic system structures
Septum, amygdala, hippocampus
Septum
one of the primary pleasure centers; stimulation results in intense pleasure and sexual arousal; inhibits aggression
Damage to septal region –> septal rage (lack of inhibition of aggression)
Olds & Milner (1950s)
Discovered that mild stimulation of septum is reported to be intensely pleasurable and sexually arousing; demonstrated that when rats could sitmulate their septal regions at will, they preferred it to eating, even after having gone 24 hours without food
Amygdala
Role in defense and aggressive behaviors; damage results in marked reduction of aggression and fear reactions, lesions also lead to docility and hypersexual states
Klüver and Bucy
Performed studies that linked amygdala with defensive and aggressive behavior in monkeys; bilateral removal of amygdala leads to changes identified as Klüver-Bucy syndrome
Hippocampus
Learning and memory; discovered hippocampus relationship to memory by experience of H.M.
Polarized neuron
Resting potential is net negative charge inside the neuron
Sodium-Potassium pump
Higher concentration of K+ inside cell and Na+ outside cell; Na+ flows into the cell and K+ flows out. In order to maintain neg. charge, Na+ is actively pumped out of the cell.
Four stages of action potential
Resting potential, depolarization, action potential, hyperpolarization
Action Potential Spike
Na+ rushes into cell, then K+ rushes out
Refractory period (Absolute and Relative)
Absolute: depolarization of action potential; cell is completely unresponsive to any additional stimulation
Relative: corresponds to repolarization/hyperpolarization; stronger stimulation is required to reach threshold potential than when cell is at normal resting potential
Saltatory Conduction
Conduction along a myelinated axon
nodes of Ranvier
unmyelinated gaps along myelinated axon; AP is regenerated at each node
EPSPs and IPSPs
excitatory and inhibitory postsynaptic potentials; are graded and weaken as they travel
Eric Kandel
Demonstrated that changes in synaptic transmission underlie changes in behavior; as sea snail experienced habituation and stopped withdrawing their gills, the neurons governing this reflex released smaller amounts of neurotransmitter than before.
