Biology of behavior

Nervous System

Complex communication network made up of neurons

Why do psychologist study the brain?

thoughts, feelings, and behaviors can be traced to electrical and chemical signals through the brain and body

Neurons

specialized cell that transmits messages to other neurons, glands, and muscles

dendrites

RECIEVES neural messages from other neurons

cell bosy (soma)

houses DNA

Axon

thin tube that transmits messages

Glial cells

a support cell within the nervous system

What do glial provide?

structure for the neuron

What do glial cells form

a) blood-brain barrier

b) myelin sheat

blood-brain barrier

prevents toxins rom entering brain

myelin sheath

specialized cell that are wrapped around the axom to help tramsit message

How do Neurons communicate

1) Electrical signal within a neuron (action potential)

2) Chemical signal between neurons (neurotransmitters)

Action potential

electrical impulse that travels from the cell body down to the end of the axon (neural firing)

Threshold

levels of electric charge needed to stimulate action potential

All-or-none response

Once the electric charge of the neuron reaches a certain threshold, it fires an action potential

synapse

junction between 2 neurons

How are stronger signals (e.g., louder sounds) reflected in neuronal activity?

through firing more action potentials mor frequently and activating a larger number of neurons.

Neurotransmitters

chemical messenger that travel across synapse from sending neuron to receptors on receiving neuron

reuptake

sending neurons reabsorbs excess neurotransmitters

excitatory signals

increase likelihood that neuron will fire

inhibitory signal

decrease likelihood that neurons will fire

Motor neurons

carry signals from brain or spinal cord to muscles, skin, and gland

Sensory neurons

carry messages from receptors to spinal cord and brain

What is in the central nervous system

brain and spinal cord

function of CNS

a) responds to sensory information

b) sends messages to muscles, glands, organs

spinal cord

extension of the brain

What does the spinal cord do

a) handles both incoming and outgoing messages

b) acts as bridge between brain and body below neck

Spinal reflexes

automatic responses that occur without any brain involvement

What is the peripheral nervous system?

All of the nervous system outside the brain and spinal cord

Funtion of PNS

a) allows communication between CNS and sensory systems

b) contains somatic and autonomic nervous systen

Somatic nervous system

(Voluntary) sensory and motor pathways

Autonomic Nervous system

(automatic) Has sympathetic and parasympathetic nervous system

Sypathetic nervous system

increase physiological arousal (fight or flight)

Parasympathetic nervous system

decreases arousal (rest and digest)

Hormones

chemicals secreted by endocrine glands into bloodstream

hypothalamus

controls pituitary glands

pituitary gland

“master gland”

Adrenal Glands

helps trigger “fight or flight”

what hormones are released by adrenal gland

Cortisol

Aldosterone

adrenal androgens and estrogen (sex hormones)

electroencephalogram (EEG)

Detects electrical activity of neurons in particular regions of breain

PET scan (position emission tomography)

records biochemical changes in brain as they are happening in different locations

CAT scan - computerized axial tomography

x-ray beams sent through head. Takes pictures of brain tissue

MRI

uses magnetic field to measure activity of various brain areas

fMRI (functional magnetic resonance imaging)

uses MRI to measure relative activity of various brain areas during tasks (how the brain reacts to other images)

Older brain structures

Brainstem (medulla, pons)

reticular formation

thalamus

cerebellum

Limbic system

amygdala

hypothalamus

hippocampus

Cerebral cortex

4 lobes: frontal, temporal, parietal, and occipital

Medulla

Controls life-sustaining bodily functions

Pons

involved in sleep; connects cortex to lower brain region

Reticular formation

controls alertness: attention

thalamus

relay station - directs incoming information from sensory receptors to cerebral cortex

Cerebellum

Coordination of movement (balance, memory of simple skills)

Amygdala

emotions - aggression, fear

Hypothalamus

regulars endocrines activity

• controls hormone release

  • reward/pleasure

hippocampus

“gateway to memory”

• enables formation of new conscious memories

Cerebral Cortex

higher form of thinking

how many hemispheres of cerebral cortex

2 (left and right)

Frontal lobes

(front of the brain)

• planning, creative thinking, personality

• contain motor cortex - voluntary movement

Homonulus

map of motor (sensory) cortex

Broca’s area

speech production (left frontal lobe)

Mirror neurons

fires when observing another person doing something

Parietal lobes

contain somatosensory cortex - receives information about touch sensation

occipital lobes

contains visual cortex - processes visual signals

Temporal lobes

Contains auditory cortex - processes sounds

contains wernicke’s area - language comprehension