BIOLOGICAL BASES OF BEHAVIOUR

neuron

cell of nervous system specialized for sending and receiving neural messages

sensory neurons

carry messages from the sensory organs to spinal cord + brain

motor neurons

carry messages from brain + spinal cord to muscles and glands

interneurons

collect, integrate, + retrieve messages from various sources

dendrites

receive chemical messages from other neurons

cell body/soma

collects neural impulses, contains nucleus, sustains cell functions

axon

transports electrical impulses to other neurons via the terminal branches

axon terminals

converts electrical signals into chemical messages

myelin sheath

fatty layer that insulates the axons + speeds up transmissions of electrical signals

glia

nervous system cells that perform variety of critical support functions (eg. provides structural support, clean up debris, nutrient supply)

action potential

how neurons talk to each other via firing off electrical impulses (generated at junction between axon + cell body)

cell membrane

thin fatty skin enclosing the neuron (separation between intracellular fluid and extracellular fluid)

before an action potential

at rest, more negative ions are inside the cells relative to outside

resting potential

electrical charge across the membrane with more negative charge inside (-75 to -55 mV)

beginning depolarization

when a neuron is sufficiently stimulated by other neurons ions channels open at end of axon and positively charged sodium ions begin to enter

depolarization

when electrical charge across the membrane egins to reverse

voltage threshold

critical level to which a neuron’s membrane potential must be depolarized to initiate action potential

action potential

the moment when interior of cell is more positively charged than the outside

repolarization

after action potential, when sodium ions close but potassium ions remain open to allow flow out of the cell

refractory period

temporary dip between resting potential when the neuron struggles to refire

synaptic cleft

gap that separates neurons

communication across the synaptic cleft

electrical signals are converted to chemical signals via the sending of neurotransmitters (triggered by arrival of action potential)

neurotransmitters

chemical messengers sent between synapses

ways neurotransmitters are removed from the synapse

diffusion (drifting), degradation (broken down), reuptake (reabsorption into the presynaptic terminal)

excitation of neurotransmitters

receiving the neuron slightly depolarized (moving it closer towards voltage threshold + increasing likelihood of action potential)

inhibition of neurotransmitters

receiving the neuron slightly hyperpolarized (moving it further from voltage threshold + reducing likelihood of action potential)

types of neurotransmitters

GABA, acetylcholine, serotonin, dopamine, norepinephrine

GABA

• amino acid

• most common inhibitory neurotransmitter

• responsible for downregulation of stress, anxiety, fear

acetylcholine

• triggers both excitatory and inhibitory signals

• commonly found in neuromuscular junction

• plays key role in autonomic nervous system + the brain circuits involved in learning + memory

norepinephrine

• important for fight or flight

• contributes to arousal (attention) + vigilance

serotonin

• contributes to regulation of sleep, appetite, mood + aggression

dopamine

• involved in movement, planning + Aspects of reword

• most addictive drugs stimulate higher levels of activity in dopaminergic circuits

psychoactive drug

chemical substance that alters a person’s thoughts feelings, or behaviours by influencing activity of neurotransmitters

agonist

enhances action of a neurotransmitter

how agonists work

increase neurotransmitter release, blocks neurotransmitter uptake, or mimics neurotransmitter to activate its postsynaptic receptor

antagonist

inhibits action of a neurotransmitter

how antagonists work

block neurotransmitter release, destroys neurotransmitter in synapse, or mimics neurotransmitter to block its postsynaptic receptor

nerve

bundle of neurons

central nervous system

brain + spinal cord

peripheral nervous system

nerves connecting brain to the rest of the body

components of peripheral nervous system

• somatic nervous system

• autonomic nervous system

somatic nervous system

carries commands for voluntary movement from CNS to muscles

autonomic nervous system

carries involuntary commands to organs, blood vessels + glands

components of autonomic nervous system

• sympathetic branch

• parasympathetic branch

sympathetic nervous system

prepares body for situations requiring energy (fight or flight)

parasympathetic nervous system

controls glands + organs during calm periods, returning body to resting state (rest + digest)

endocrine system

network of glands (hormone-sending organs) that work with central and autonomic nervous system

hormone

blood-borne chemical messengers

adrenal hormones

hormones released by adrenal glands (on top of kidneys) during stressful events

• boost energy, increase heart rate + blood pressure

• ex. cortisol + adrenaline

pituitary gland

master gland that directs other glands (regulates hunger, sexual arousal, growth + sleep)

oxytocin

hormone released into bloodstream by pituitary gland (plays role in social bonding as those with higher levels are more trusting of others and show an improved ability to accurately perceive the emotions of people to whom they feel similar)

spinal cord

initiates spinal reflexes (aka responses to stimuli without involvement of the brain)

brainstem

lowest region of the brain that sits on top of the spinal cord

midbrain

controls salient stimuli (tegmentum), movement (substantia nigra), motivation + rewards (ventral tegmental area), downregulation of pain (periaqueductal grey)

medulla

controls heart rate, blood pressure, reflexes like coughing + swallowing

pons

controls breathing, balance, + coordination

reticular formation

controls arousal, attention, wakefulness

cerebellum

controls coordination, balance, precise movements + accurate timing

limbic system

known as the emotional brain (includes hypothalamus, thalamus, amygdala, hippocampus, basal ganglia)

hypothalamus

interface between brain + body, homeostatic regulation, fight-or-flight, directs autonomic nervous system + endocrine system

thalamus

relay station for all sensory signals (but smell), alertness + consciousness

amygdala

processing emotional significance of sensory info, works with hippocampus to create vivid memories

psychic blindness

normal vision but visual stimuli lose their emotional signficance (caused by damage to the amygdala)

hippocampus

memory, spatial recognition, mental time traval

basal ganglia

planning, executing + controlling voluntary movement, suppression of unwanted movement (substantia nigra), reward + pleasure (nucleus accumbens)

cerebral cortex

largest + outermost part of the human brains, further divided into lobes

frontal lobe

movement + planning, contains primary motor cortex + prefrontal cortedx

primary motor cortex

a map of the body’s muscles

prefrontal cortex

conscious experience of emotions

executive function

planning, judgement, decision making

primary somatosensory cortex

map of the body’s skin surface that lets us process touch

parietal lobe

helps us pay attention to and locate objects + navigate surroundings, contains primary somatosensory cortex

occipital lobe

links to temporal + parietal lobes let us recognize objects + process their movement, contains primary visual cortex

primary visual cortex

necessary for sight

temporal lobe

contains primary auditory + olfactory cortex, allows you to hear/understand language, allows you to recognize objects + people

insular lobe

allows us to perceive our inner world + state of internal organs, includes the primary taste cortex

primary taste cortex

responsible for taste

association cortex

integrates incoming information from sensory areas with existing knowledge to produce meaningful experiences of the world

corpus callosum

bridge of fibers that connect the hemispheres and allows the hemispheres to talk to each other

interhemispheric transfer

2 hemispheres talking to each other

contralateral organization

each hemisphere controls primary sensory + motor functions for the opposite side of the body

lateralization

some brain functions being located on one of the two sides of the brain

what is the left side of the brain specialized for

language

what is the right side of the brain specialized for

nonverbal processing of info

broca’s area

speech production + articulation, in left frontal lobe, damage causes telegraphic speech

wernicke’s area

understanding/processing of words, in temporal lobe, damage causes fluent but nonsensical speech

phrenology

19th century belief that mental faculties + characteristics are located in specific brain regions + can be inferred from shape of the skull

neuropsychology

study of brain function by examining functional alterations

lesion

abnormal tissue from disease or trauma

single dissociation

lesion to brain structure A disrupts function X but not function Y

double dissociation

lesion to brain structure A disrupts function X but not function Y, lesion to structure B disrupts function Y but not X

deep-brain stimulation

stimulating specific parts of the brain with implanted electrodes

transcranial magnetic stimulation (TMS)

exposure to magnetic field to create temporary disruption or enhancement of cortical brain function

transcranial direct current stimulation (TDCS)

low levels of direct current delivered via electrodes on the head to stimulate brain function

types of brain-stimulation study

deep-brain stimulation, transcranial magnetic stimulation (TMS), transcranial direct current stimulation (TDCS)

single-cell recording

measurement of the electrical activity of a single neuron

electroencephalography (eeg)

recording of electrical waves from thousands of neurons using electrodes on the scalp, shows synchronized electrical response to a sensory, cognitive or motor event that lets. us see how the brain responds to specific stimuli

magnetoencephalography (emg)

recording of magnetic fields produced by the brains electrical currents

limitations of eeg/emg

tells us when brain activity happens (temporal resolution) but not where (spacial resolution)

neural plasticity

brain’s ability to change and adapt through life