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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.
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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
5 Reuptake of neurotransmitters sponged up by the presynaptic neuron 4 Destruction (by enzymes) or Breakdown Neurons 1 Neurotransmitter molecules in synaptic vesicles 2 Release of neurotransmitter molecules into synaptic cleft 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
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 • Glands that secrete hormones • 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