The Biological Basis of Behavior Chapter 3: The Biological Basis of Behavior

Biological Psychology Physiology of Behavior Biopsychology Brain & Behavior Scientific study of the biological and mental processes of behavior

Neurons Neurons or nerve cells: Individual cells in the nervous system that receive, integrate, and transmit information through chemical or electrical transmission 3 basic types : Sensory Neurons Motor Neurons Interneurons

Neurons Dendrite Receives information Cell Body or Soma Contains nucleus, keeps cell alive Axon Transmits information to another neuron Axon Terminal Buttons Secretes chemicals called neurotransmitters located at the end of the axon Axon Terminal Buttons

Neurons Myelin Sheath Protects axon and speeds up message Nodes of Ranvier Tiny gaps in the myelin sheath What is damage to the myelinated sheath called? Multiple Sclerosis (MS)

Communication Between Neurons Two ways information is transmitted: Electrical Chemical

Electrical Electrical Synapses: membranes of the two cells actually touch, and share proteins communication passes directly from one membrane to the next very fast rare, found only in the heart and the eye

Chemical Synapse: the point of communication between neurons at the synaptic cleft Presynaptic neuron: message-sending Postsynaptic neuron: message-receiving Synaptic Vesicles: little sacs inside Axon Terminal Button contain chemicals called Neurotransmitters

Chemical Synaptic cleft/gap: the gap between the axon terminal button of one neuron and the dendrite of the adjoining neuron Neurotransmitters: chemical created by neuron that transmits information from one neuron to another Synaptic transmission neurotransmitters are released, cross the synaptic gap, attach to receptor sites

Chemical Receptors: post-synaptic neurons have specific binding sites for neurotransmitters  Reuptake: neurotransmitters reabsorbed or recycled by presynaptic neuron

1 5 2 4 3 Neurons Neurotransmitter molecules in synaptic vesicles Reuptake of neurotransmitters sponged up by the presynaptic neuron 2 Release of neurotransmitter molecules into synaptic cleft 4 Destruction (by enzymes) or Breakdown When a neurotransmitter and a receptor molecule combine, reactions in the cell membrane cause a postsynaptic potential, or PSP - a voltage change at the receptor site on a postsynaptic cell membrane. After producing postsynaptic potentials, some neurotransmitters either become inactivated by enzymes, or drift away. Most neurotransmitters, however, are reabsorbed into the presynaptic neuron through reuptake - a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane. 3 Binding of neurotransmitters at receptor sites on postsynaptic membrane

Neurons: How The Message Gets Its Power Action Potential: a brief electrical impulse that travels along the axon See it in Action Threshold: each neuron has a minimum level to be activated All-or-None Law: sufficiently stimulated- action potential occurs, not sufficiently stimulated—action potiential does not occur! Absolute Refractory Period: mimimum length of time until another action potential can begin Resting Potential: stable negative charge of a neuron and no signal is being transmitted –70 millivolts Video

Neurotransmitter Chemicals Neurotransmitters: Affect learning, memory, mood, behavior and mental illness Acetylcholine: muscle control; contributes to regulation of attention, arousal and memory. Dopamine: Pleasure, Learning, Emotion, Motivation, Movement, (not enough) Parkinson’s, (too much) Schizophrenia Serotonin: Mood, Appetite, Sleep, Depression Norepinephrine: Stress, learning, ADHD, depression Endorphins: Pain Reliever; Drug Addiction Video

Studying the Brain EEG (Electroencephalograph) – electrodes record brain wave patterns CAT/CT (Computerized Axial Tomography) – cross sectional series of X-Rays MRI (Magnetic Resonance Imaging) – magnetic fields identify tissue types fMRI (functional Magnetic Resonance Imaging) – magnetic field identifies structure & function PET (Positron Emission Tomography) –decay of radioactive material used to visualize brain activity & use of nutrients

Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS)

Central Nervous System Central Nervous System (CNS): Brain and Spinal Cord; interprets, processes and responds to incoming information

Peripheral Nervous System Peripheral Nervous System (PNS): Links all of the nerves outside of Central Nervous System to the body 2 Divisions of the PNS: Somatic Nervous System: sensory info Autonomic Nervous System: involuntary functions Sympathetic: mobilizes fight or flight Parasympathetic: conserves resources

Autonomic Nervous System Sympathetic – activates organs and glands; fight/flight stress response Parasympathetic – calms body, recovery

Brainstem Midbrain Hindbrain

Brainstem Midbrain Hindbrain: Medulla Pons Cerebellum

Brainstem: contains the hindbrain and midbrain and connects the spinal cord to the rest of the brain Midbrain: helps process auditory and visual information Hindbrain: connects spinal cord to brain Medulla: Controls vital functions, (breathing, heart rate, digestion) Pons Cerebellum: balance, muscle movements, motor skills

Forebrain/Cerebrum Forebrain or Cerebrum: involved in complex behaviors and cortex mental processes which are divided into 2 hemispheres The hemispheres are divided into four lobes: Frontal lobe: thinking, planning, reasoning, self-control and voluntary muscle movements Temporal lobe: Processes auditory information Occipital lobe: Processes visual information Parietal lobe: Processes bodily sensations

Frontal Lobes Control Thinking, planning, judgment, impulse control Broca’s area: L frontal lobe; production of language Broca’s aphasia: damage/loss of speech Association Areas: sensory and motor information is combined and associated with stored knowledge. Motor Cortex: Movement; signals to spinal cord & cerebellum Damage

Cerebrum Cerebral cortex Corpus callosum Cerebral Cortex: higher cognitive processes (ie: thinking, language, reasoning) Corpus Callosum * R & L Brain connection split brain Cerebral Hemispheres * (in most people) R = perceptual skills, drawing pictures L = language, math Cerebellum Medulla

Limbic System Limbic System: group of forebrain structures involved in emotion, motivation, learning, and memory Hippocampus: Memory formation Amygdala: Aggression, fear, anger, disgust, stress and other emotions. Also involved in learning and in memory formation, especially emotional memories.

Limbic System Thalamus: Involved in regulating levels of awareness, attention, motivation, and emotions Hypothalamus: regulates both divisions of the autonomic nervous system and behaviors related to survival, such as eating, drinking, frequency of sexual activity, fear, and aggression Links nervous system to endocrine system via pituitary gland

ENDOCRINE SYSTEM Hormones = Glands that secrete hormones Chemical messengers in the bloodstream. Hormones help regulate emotions and behaviors.

Plasticity The brain’s ability to change its structure and function in response to experience or damage