Biological Basis of Behavior

The Neuron Dendrites Cell Body/Soma Axon (blue represents myelin sheath- insulation for electrical impulse) Axon Terminus/ Terminal Buttons

Neuron Firing  At rest, the neuron is in a state of resting potential  Signal is received by receptors on the dendrite  If the signal reaches the threshold an action potential is initiated  Once an action potential is initiated there is an all-or-nothing response (it fires or it doesn’t)  The action potential is an electrical impulse that travels down the axon  When the electrical impulse reaches the terminal buttons, neurotransmitters or chemical messengers are released into the synapse the space between the sending neuron and the receiving neuron  The neurotransmitters then bind with the receptors on the dendrite of the next neuron  Excitatory neurotransmitters keep the signal going  Inhibitory neurotransmitters stop the signal from continuing  Once the action potential has been sent, the neuron must go through a refractory period a time of rest between impulses. During this time reuptake of neurotransmitters occurs when they are brought back into the original sending neuron in preparation to be used again.

Neurotransmitters  Chemical messengers that send a signal from one neuron to the next  Remember! The signal through one neuron is due to electricity, signals between neurons is due to chemicals

NeurotransmittersFunctionToo MuchToo Little Acetylcholine (Ach) Enables muscle action, memory, and learning SeizuresAlzheimer's DopamineLearning, movement, attention, emotion SchizophreniaParkinson’s disease, tremors, depression when paired with low serotonin SerotoninMood, hunger, sleep, arousal Depression NorepinephrineAlertness and arousalDepression GABAMajor inhibitory neurotransmitter Seizures, tremors, insomnia GlutamateMajor excitatory neurotransmitter, involved in memory Migraines and seizures EndorphinsReleased in response to pain OxytocinEnables feelings of love and bonding Maladaptive social interactions; aggression

Drugs and Neurotransmitters  Agonist drugs-  The place of and serve the same function as a neurotransmitter  Used when there is too little of a neurotransmitter present  Antagonist-  Take the place of a neurotransmitter but interrupt its function  Used when there is too much of something

Divisions of the Nervous System

The Endocrine System  Closely associated with the nervous system  Contains glands that release hormones into the blood stream  Together with the nervous system maintains homeostasis our body’s internal balance  Pituitary Gland- located in the base of the brain, known as the master gland because it controls all the others  Adrenal Glands- top of kidneys, release epinephrine and norepinephrine in response to stress to trigger the fight or flight response

Neurotransmitters vs. Hormones Neurotransmitters  Chemical messengers  Nervous system  Released from terminal buttons on the neuron into the synapse  Work fast  Don’t stay around long Hormones  Chemical messengers  Endocrine system  Released from endocrine glands into the blood stream  Work slowly  Stay around for a while

Studying the Brain

Electroencephalogram EEG  Records the brain’s electrical activity  Electrodes detect brain-wave activity  Can assess brain damage and epilepsy

Computer Tomography (CT or CAT Scan)  Examines the brain by taking x-ray photographs  Uses radiation  Can diagnose brain damage, bleeding, and stroke

Magnetic Resonance Imaging (MRI)  Uses a magnetic field that detects the movement of electrons  Produces a detailed image of the soft tissue in the brain  Can show unique features or abnormalities in brain tissue

Functional MRI (fMRI)  Taking images before and after being asked to do a task  Can show where blood is flowing during specific tasks or when eliciting specific emotion

Positron emission tomography (PET)  Shows functional areas of the brain by observing the presence of radioactive glucose  Similar to fMRI can show what area of the brain is functioning during a specific task or emotional response

Organization of the Brain

Older Brain Structures  Brainstem  Medulla- heartbeat and breathing  Pons- coordinates movement  Reticular formation- controls arousal  Thalamus-  Sensory control center, receives information from senses and sends it to the higher brain regions for processing  Receives higher brain’s relies and directs the medulla and cerebellum  Cerebellum  Nonverbal learning and memory  Coordinates voluntary movement

Limbic System  Hippocampus  Relay center for conscious memory processing; “save button”  Amygdala  Emotional memory processing  Specifically linked to fear and aggression  Hypothalamus  Bodily maintenance  Hunger, thirst, body temperature, sexual behavior  Also linked to emotion and reward

Cerebral Cortex  External area of the brain  Where advanced thinking and planning occurs  Where memories are stored

Occipital Lobes  Responds to visual stimuli  Interprets what is being “seen”

Temporal Lobes  Hearing  Language processing  Memory

Frontal Lobes  Personality  Intelligence  Voluntary movement (centered in the motor cortex)

Parietal Lobes  Spatial location  Attention  Processes information about body sensation (somatosensory cortex)

Association Cortex  Neurons that make up about 75% of the cortex  Integrate sensory and motor information