Chapter 3: Biological Foundations of Behaviour Flashcards
Neurons
3 main parts:
-Cell body / soma
-Dendrites
-Axon
Cell body / soma
-contains stuff that keeps neutron alive
-contains genetic information for cell development and function
Dendrites
-branch-like fibres
-collect messages from other neurone and sends them to the soma
-receiving end of the neuron
Axon
-branches out to form an axon terminal
-conducts electrical impulses to other neurons, muscles, glands
-connects with dendritic branches to connect neurons
Glial cells
-surround neurons
-holds them in place
-manaufacture nutrients
-absorbs toxins and waste
-blood-brain barrier prevents substances from entering the brain
Nerve Conduction
-neurons are surrounded by salty liquid with Na+
-the inside of a neuron is more negative
Action Potential
the sudden several in neuron’s membrane voltage
Depolarization
-increases in mV from -70 to 40
Graded Potentials
-changed proportional to the incoming stimulation
-ion channels: tiny protein structures that open to let more Na+ into the neuron and making it less negative
-then they close quickly, then K+ channels open to let them out and restores neuron to resting potential
Refractory Period
-time where the membrane is not excitable and can’t discharge more action potential
Myelin sheath
-fat insulation layer made of glial cells that covers axons
-it allows for high conduction speeds along the axon
Synaptic Transmission
-Otto Leowi discovered that neurons release chemicals to pass to the next neuron
-there are synaptic clefts between axon terminals and dendrites
-neurotransmitters are produced and carry messages across a synapse to excite or inhibit other neurons
-occurs in five steps:
#1: synthesis
#2: storage
#3: release (caused by action potential, chemical molecule leave)
#4: binding (they bind to receptor sites)
-excitation: depolarization of the cell membrane by stimulating the flow of Na+ into the cell
-inhibition: stimulating ion channels to let K+ flow out, or lets -’ve ions flow in to make it more negative
#5: deactivation
-neurotransmitters continue to function until they are deactivated
-some are deactivated by chemicals that break them down
-Reuptake: they are reabsorbed into axon terminals
Examples of Neurotransmitters
-Acetylcholine (inhibition of memory, motor, behaviour)
-Norepinephrine (arousal and eating)
-Dopamine (arousal and voluntary movement)
-Serotonin (sleep and thermoregulation)
-Gamma Aminobutyric Acid (motor behaviour)
Drugs that affect Neurotransmitters
-some drugs increase or decrease neurotransmitter amounts, stimulates or blocks receptor sites, or blocks transmitter function
-Cocaine: stimulates release of dopamine
-Caffeine: blocks adenosine receptor sites
The Nervous System
-3 major types of neurons
#1: sensory neurons (carry input messages from organs to the brain)
#2: motor neurons (transmits output messages from the brain to organs)
#3: interneurons (performs connective functions to link everything together)
Peripheral Nervous System
-all neural structures that aren’t the brain or the spinal cord
-neurons travel along this to carry messages
-2 major divisions
2 Major Divisions of the Peripheral Nervous System
1: somatic nervous system: sensory and motor neurons to control sensations and voluntary movements
#2: autonomic nervous system: controls glands, involuntary muscles, has 2 divisions
-sympathetic nervous system: activation and arousal functions (increased heart beat, dilated pupils)
-parasympatheic nervous system: slows down the body
-homeostasis: balanced state
Central Nervous System
-the brain and spine
-the spine is protected by vertebrate, the brain is protected by the skull
-Neuropsychological Tests: measures behaviours to locate brain damage
-Destructive and Stimulation techniques: controlled damaging for research
-Electrical Recording: analyzing EEG graphs
-Brain Imaging: CT scans, PET scans, MRI
Structure and Behavioural Functions of the Brain
1: Hindbrain
#2: Midbrain
#3: Forebrain
#4: Cerebral Cortex
Hindbrain
1: brain stem:
-medulla controls heart rate and transpiration
-pons is a bridge that helps nerve impulses to travel
-two way stem, connects to the spinal cord
#cerebellum:
-look like a little brain attached to the brain stem
-timing of muscular movement coordination
-they are initiated in higher brain centres
-learning, memory
Midbrain
-composed of clusters of sensory and motor neurons, as well as tracts to connect higher and lower portions of the nervous system
-Reticular Formation: acts as a sentry to alert higher centres of incoming signals, affects sleep, wakefulness, and attention
Forebrain
-2 large cerebral hemispheres that wrap around the brain stem
-outer portion is covered by the cortex
-Thalamus: reroutes sensory inputs towards appropriate brain area
-Basal Ganglia: voluntary motor control
-Hypothalamus: sexual behaviour, temperature regulation, eating, etc.
-Limbic System: motivational and behavioural
-Hippocampus: forming and retrieving memories
-Amygdala: organizes emotional response
Cerebral Cortex
-thick sheet of grey cells on the outermost layer of the brain
-four lobes: frontal, parietal, occipital, temporal
-Motor cortex: controls muscles
-Sensory cortex: sensations, balance
-Speech comprehension and production;
-Wernicke’s area: language comprehension
-Broca’s area: normal speech production
-Association cortex: found in all cerebral cortex lobes, highest mental functions
-Frontal lobes: includes Broca’s area, motor cortex, and an associative cortex
-also involved in emotional experience
-Prefrontal Cortex: directing behaviour and adapting
Hemispheric Lateralization
-Corpus callosum is a neural bridge that acts as a communication link between the two hemispheres
-Lateralization: localization of a function in one of two hemispheres
-left: verbal abilities, speech, math, logic, positive emotions
-right: imagery, music, art, relationships, negative emotions
-if the corpus callosum is cut, visual input in one hemisphere will only project stimulus to one side of the visual field
-Split Brain Experimentations
Brain Plasticity
-Neural plasticity: neurons can change in structure and function
-early experiences during brain development can alter brain areas
-greater amount of synapses in children allow for a greater change of recovery from damage
-adults can maintain and recover function when surviving neurons adapt and modify
