3: biological bases of behavior

neurons

individual cells in the nervous system that receive, integrate and transmit information

soma (cell body)

contains the cell nucleus and much of the chemical machinery common to most cells

dendrites

parts of the neuron that are specialized to receive information

myelin sheath

• insulating material that encases some axons

• speeds up the transmission of signals that move along axons

condition in which the myelin sheath degenerates

multiple sclerosis

axon

long thin fiber that transmits signals away from the soma to other neurons or to muscle glands

axon terminal / terminal button

small knob that secretes chemicals known as neurotransmitters

synapse

a junction where information is transmitted to one neuron to another

neurotransmitter

chemicals which serve as messengers that may activate nearby neurons

glia

cells found throughout the nervous system that provides various types of support for neurons

synaptic cleft

microscopic gap between the terminal button of one neuron and the cell membrane of another neuron

information flow in neurons

dendrites → cell body → axon

resting potential of a neuron

its stable, negative charge when the cell is inactive

the action potential

a very brief shift in a neuron’s electrical charge that travels along an axon

absolutely refractory period

minimum length of time after an action potential, during which another action potential cannot begin, usually 1-2 milliseconds

all-or-none law

either a neuron fires or doesn't, stating that the strength of a neuron’s response doesn't depend on the strength of the stimulus

postsynaptic potentials

a voltage change at a receptor site on a postsynaptic cell membrane

expiatory post synaptic membrane

• positive voltage change

• increased likelihood that the postsynaptic neuron will fire action potentials

inhibitory postsynaptic potential

• negative voltage change

• decreased likelihood that the postsynaptic neuron will fire action potentials

reuptake of neurotransmitters

a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane

acetylcholine (ACh)

is found throughout the nervous system, and is the only neurotransmitter between motor neurons and voluntary muscles

released by motor neurons controlling skeletal muscles

contribute to attention, arousal, and memory (inadequate supply can lead to alzheimer's)

Dopamine (DA)

contributes to control of voluntary movement

DA circuits known as “reward pathways”

degeneration → Parkinson’s disease

overactivity → schizophrenia

Norepinephrine (NE)

Contributes to mood regulation and arousal

disorders associated with dysregulation → depression

Serotonin

involved in regulation of sleep and wakefulness, eating, aggression

dysregulation → depressive disorders, OCD, eating disorders

GABA (gamma-aminobutyric acid)

seems to produce only inhibitory postsynaptic potentials

dysregulation → anxiety disorders

endorphins

internally produced chemicals that resemble opiated in structure and effects

PNS

made up of nerves that lie outside the brain and spinal cord

nerves

bundles of neuron fibers (axons) that are routed together in the PNS

Afferent nerve fibers

axons that carry information inward to the CNS, from the periphery of the body

Efferent nerve fibers

axons that carry information outward of the CNS towards the periphery of the body

Somatic nervous system

made up of nerves that connect to voluntary skeletal muscles and to sensory receptors

Autonomic Nervous system

nerves that connect to the heart, blood vessels, smooth muscles, and glands

Sympathetic division in ANS

mobilizes the body’s resources for emergencies

Parasympathetic division in ANS

generally conserves bodily resources, to save and store energy

CNS

consists of the brain and spinal cord

CNS bathed in what, for what

Cerebrospinal fluid (CBF), which nourishes and cushions the brain

Spinal cord function

carry the brain’s commands to peripheral nerves, and relay sensations from the periphery body to the brain

Lesioning

destroying a piece of the brain

Electrical stimulation of the brain (ESB)

sending a WEAK current into a brain structure to stimulate it

CT (computerized tomography) scan

X-ray of the brain structure, horizontal slice of the brain

MRI (magnetic resonance imaging)

map out a 3d, high resolution images of the brain structure

PET (positron emission tomography)

to map chemical activity in the brain over time

Functional magnetic resonance imaging (fMRI)

monitor blood flow and oxygen consumption in the brain to identify areas of high activity

Parts of the hindbrain

• medulla

• pons

• cerbellum

Medulla

controls largely unconscious but essential functions such as breathing, maintaining muscle tone and regulating circulation

Pons

includes a bridge of fibers that connects the brainstem with the cerebellum, also contains several clusters of cell bodies involved with sleep and arousal

Cerebellum

relatively large and deeply folded structure adjacent the the back surface of the brainstem

involved in the coordination of movement and is critical to the sense of equilibrium/ physical balance, key role in sensing the position of our limbs

brain circuits running from the cerebellum to the prefrontal cortex seem to be involved in high-order functions, like attention, planning and visual perception

The midbrain

• integrates sensory processes

• releases dopamine involve in the performance of voluntary movements

• reticular formation contributes to he modulation of muscle reflexes, breathing and pain perception, as well as regulation of sleep and arousal

the forebrain

the largest and most complex region of the brain, consisting of the thalamus, hypothalamus, limbic system and cerebrum

the thalamus

a structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex

hypothalamus

a structure found near the base of the forebrain that is involved in the regulation of basic biological needs

fighting, fleeing, feeding, mating

limbic system

• hippocampus and adjacent structures play a role in in consolidation of memories for factual information

• amygdala: centre role in the learning of fear response and other basic emotional responses

cerebrum

• cerebral cortex: convoluted outer layer of the cerebrum

• cerebral hemispheres: the right and left halves of the cerebrum

corpus callous

major structure that connects the 2 hemispheres

frontal lobe function

primary motor cortex, controls the movement of muscles

more of the cortex is dedicated to muscles we have find control over (lips fingers, tongue)

prefrontal cortex — executive control system

temporal lobe

primary auditory cortex, devoted to auditory processing

occipital lobe

includes the cortical area where most VISUAL signals are sent and visual processing is begun

parietal lobe

primary somatosensory cortex, area that registers sense of touch; integrate visual input

Broca’s area

production of speech

Wernick’s area

comprehension of language

Neurogenesis

formation of new neurons

stress → surprise the rate of neurogenesis

physical exercise → enhances the rate of neurogenesis

What processing does the right and left brain do?

Spatial musical, visual — R

Verbal — L

chromosomes

threadlike strands of DNA molecules that carry genetic information

Genes

DNA segments that serve as key functional units in hereditary transmission

polygenic traits

characteristics that are influenced by more than one pair of genes

family studies

researchers assess hereditary influence by examining blood relatives to see how much hey resemble one another on a specific trait

twin studies

researchers assess heredity influence by comparing the resemblance of identical and fraternal twins with respect to a trait

adoption studies

assess hereditary influence by examining the resemblance between adopted children and both they biological and their adoptive parent

natural selection

principle stating that heritable characteristics that prove a survival or reproductive advantage are more more Riley than alternative characteristics to be passed on to subsequent generations, and thus they come to be selected over time

adaptation

an inherited characteristic that increases in a population through natural selection, bc it helped solve a problem of survival or reproduction during the time it emerged