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Chapter 2. Biology and Behavior. Questions We Will Be Addressing in This Chapter. What are neurons, and what do they do? How do sights and sounds reach my brain? How is my brain wired? How do biochemicals affect my mood? How can my hormones help me in a crisis?. Biological Psychology.
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Chapter 2 Biology and Behavior
Questions We Will BeAddressing in This Chapter What are neurons, and what do they do? How do sights and sounds reach my brain? How is my brain wired? How do biochemicals affect my mood? How can my hormones help me in a crisis?
Biological Psychology All behavior and mental processes are based on biology. But, those processes are also influenced by the environment! Two primary systems direct the activities of the body. The nervous system The endocrine system
Cells of the Nervous System What are neurons, and what do they do?
Cells of the Nervous System Glial cells Help neurons communicate Malfunctions may lead to problems Neurons Have the ability to send and receive signals.
The Peripheral Nervous System: Keeping in Touch with the World How do sights and sounds reach my brain?
Somatic Nervous System Sends sensory information to central nervous system for processing. Sends messages from central nervous system to muscles to direct motion.
Autonomic Nervous System Controls activities normally outside of conscious control. Two Subsystems Sympathetic nervous system “Spends” energy Parasympathetic nervous system “Preserves” energy
The Central Nervous System: Making Sense of the World How is my brain “wired”?
The Central Nervous System Consists of spinal cord and brain Clusters of neuron cell bodies called nuclei Fiber tracts are bundles of axons that serve as pathways
The Spinal Chord Receives signals from the senses and passes them to the brain. Can direct simple behaviors “Reflexes”
The Brain Most complex element of CNS Three major subdivisions: Hindbrain Midbrain Forebrain
Techniques for Studying the Brain EEG – electroencephalograph PET – positron emission tomography MRI – magnetic resonance imaging TMS – transcranial magnetic stimulation
EEG(Electroencephalograph) Technique: Multiple electrodes are pasted to outside of head. What it shows: A single line that charts the summated electrical fields resulting from the activity of billions of neurons.
EEG (cont’d) Advantages Detects very rapid changes in electrical activity, allowing analysis of stages of cognitive activity. Disadvantages Provides poor spatial resolution of the source of electrical activity. Sometimes combined with magnetoencephalography (MEG).
PET(Positron Emission Tomography) Technique: Positrons and photons are emissions from radioactive substances. What it shows: An image of the amount and localization of any molecules that can be injected in radioactive form, such as neurotransmitters, drugs, tracers for blood flow or glucose use.
PET (cont’d) Advantages Allows functional and biochemical studies. Provides visual image corresponding to anatomy. Disadvantages Requires exposure to low levels of radioactivity. Provides better spatial resolution than that of EEG, but poorer than that of the MRI. Cannot follow rapid changes (faster than 30 seconds).
MRI(Magnetic Resonance Imaging) Technique: Exposes the brain to magnetic field and measures radio frequency waves. What it shows: Traditional MRI provides high resolution image of brain anatomy fMRI shows changes in blood flow. DTI shows water flow in neural fibers.
Advantages of MRI Requires no exposure to radioactivity. Provides high spatial resolution of anatomical details (<1 mm). Provides high temporal resolution (<1/10 of a second).
VIDEO: Evaluating Patients with Brain Damage Discussion questions
Transcranial Magnetic Stimulation (TMS) Technique: Temporarily disrupts activity of a small region of the brain by exposing it to an intense magnetic field. What it shows: Normal function of a particular brain region can be studied by observing changes after TMS is applied to a specific location.
Transcranial Magnetic Stimulation (TMS)(cont’d.) Advantages Shows which brain regions are necessary for given tasks. Disadvantages Long-term safety not well established.
fMRI (functional MRI) Combines advantages of PET and MRI Thinking Critically – What Can fMRI Tell Us about Behavior and Mental Processes?
VIDEO: MRI as Lie Detector Discussion questions
Hindbrain Lies just inside the skull; continuation of spinal cord Medulla – regulates heart rate, blood pressure, and breathing Cerebellum – controls fine motor skills, eye tracking, storehouse for well-rehearsed movements
Midbrain Lies above the hindbrain Together with parts of hindbrain form brain stem Helps produce smooth movements
VIDEO: Neural Networks Discussion questions
Forebrain Controls most complex aspects of behavior and mental life Outer surface called cerebral cortex Hypothalamus and thalamus help operate basic drives, emotions, sensations Thalamus – acts as relay station for pain and sense organ signals (except smell) Hypothalamus – helps regulate hunger, thirst, sex drives
Forebrain (cont.) Amygdala and hippocampus help regulate memory and emotion Amygdala – links different types of sensory info in memory, such as shape and feel of objects Hippocampus – helps form new memories
Results from Split-Brain Studies Image presented to left visual field: Person can name the object. Image presented to right visual field: Person cannot describe object in words. But can pick the object out of a group of other objects!
Hemispheric Specialization Left hemisphere has primary control over spoken language. Right hemisphere better at tasks involving spatial relationships. Also at recognizing human faces. But differences shouldn’t be exaggerated. Corpus callosum allows the two hemispheres to work closely together.
Plasticity in the CNS CNS has the ability to: Strengthen neural connections at synapses Establish new neural connections Provides the basis for the ability to form new memories and learn new things. Limits to plasticity in repairing brain damage Linkages – The Changing Brain
Ways of Helping the CNS to Heal Transplant fetal tissue into the adult’s brain. Encouraging initial results But a controversial Coax the brain to repair damage by making its own new neurons. Adult brain cell contains neural stem cells Treatment problems Focus on Research – Disembodied Woman
The Chemistry of Behavior: Neurotransmitters How do biochemicals affect my mood?
Three Classes of Neurotransmitters Small Molecules Peptides Gases