Chapter 3: Nervous System Perspectives PDF

CHAPTER 3: Perspectives Materialism: Behavior can be explained by the working of the brain and the rest of the nervous system, without any refer to the mind Mentalism: The opposite, an explanation of behavior as a function of the mind. Brain and behavior are related Brain affects behavi...

CHAPTER 3: Perspectives Materialism: Behavior can be explained by the working of the brain and the rest of the nervous system, without any refer to the mind Mentalism: The opposite, an explanation of behavior as a function of the mind. Brain and behavior are related Brain affects behavior: Hyperactivity in the dopamine system is a cause of schizophrenia Behavior affects the brain: Learning can bring about long-lasting changes in the brain Cells of the Nervous System Neurons: The basic structural and functional units of the nervous system. Converting information into "binary coding" (like a computer) Glial cells: Support neurons and provide nutrition. Outnumber neurons by about 10 to 1 Three types of Neurons You can identify which type of neuron is by the location of the cell body. Sensory Neurons: Transmit sensory information. The cell body is in the center but a bit to the side Motor Neurons: Control muscles and glands. The cell body is embedded in the dendrites like a tree Interneurons: Connect neurons within the brain and spinal cord. The cell body is in the very center Sensory neuron is connected to a receptor (like the skin). The receptor stimulus sends the signal to the sensory neuron. This is connected to the Interneuron which interprets the signal and then sends it to the Motor neuron, which is connected to an effector (muscle) and produces the response (like a movement) The function of a neuron is to receive, integrate and transmit information All neurons have: Dendrites: Receive information. Axon: Sends information away from the cell body. Myelin sheath: Speeds up signal transmission. Moves from the dendrites to the cell body, to the Axon Terminals Myelin sheath Many (but not all) axons are wrapped in a myelin sheath Derived from glial cells Speeds up signal transmission along an axon Degeneration of myelin sheath will lead to: Multiple sclerosis Loss of muscle control Weakness and paralysis Vision difficulties Axon An axon ends in a terminal button filled with neurotransmitters Synapse: Connection between two neurons, or a neuron and an effector. Action potential Increase in membrane potential. When a neuron is stimulated, a brief jump focus in the neuron's voltage, a spike, is observed on the voltmeter. Occur only in nodes of Ranvier. Resting potential: -70 millivolts inside the neuron. Action potential: Sudden voltage change when a neuron is stimulated. Depolarization: Membrane becomes less negative. Repolarization: Restores negative charge after an action potential. Hyperpolarization: Relative refractory Refractory Periods: Absolute Refractory Period: Neuron can't fire again immediately. The time it needs for it to fire again is called Refractory Period. Relative Refractory Period: Neuron can fire, but with stronger stimulation. All-or-None Law: Neurons either fire or they don’t. Stronger stimuli increase the frequency, not the strength, of firing. Synaptic Transmission: A synapse is a connection between an end foot of the axon of one neuron (axon) and a dendritic spine of the other neuron. Excitatory: Positive. Makes the neuron more likely to fire (action potential). Inhibitory: Negative. Makes the neuron less likely to fire (action potential). Plasticity: Synapses can change due to learning or experience. Types of Synapses: Excitatory Synapse: Function: Increases the likelihood that the postsynaptic neuron will fire an action potential. How it works: Neurotransmitters (like glutamate) cause the inside of the postsynaptic neuron to become more positive, bringing it closer to the threshold for firing an action potential. This is called an Excitatory Postsynaptic Potential (EPSP). Inhibitory Synapse: Function: Decreases the likelihood that the postsynaptic neuron will fire an action potential. How it works: Neurotransmitters (like GABA) make the inside of the postsynaptic neuron more negative, moving it farther from the threshold needed for an action potential. This is called an Inhibitory Postsynaptic Potential (IPSP). In summary, excitatory synapses push the neuron toward firing, while inhibitory synapses make it less likely for the neuron to fire. The balance between excitatory and inhibitory signals is what determines whether a neuron will send a signal down the line. Some Neurotransmitters Dopamine: Influence movement, learning, attention and emotion Serotonin: Affects mood, hunger, sleep, and arousal. Undersupply linked to depression. Dopamine Hypothesis of Schizophrenia: Excessive dopamine activity may lead to schizophrenia. Agonists: Drugs like amphetamines mimic neurotransmitters. Antagonists: Drugs like chlorpromazine block neurotransmitters. Learning and Synapse Plasticity: Two types of Learning: Habituation Decreased response to repeated stimuli. Takes place in calcium channel Habituation is a simple form of learning in which an organism gradually reduces its response to a repeated stimulus over time. In other words, as you experience the same stimulus over and over again, you stop reacting to it as strongly or even stop reacting at all. It’s a way for your brain to filter out repetitive, non-threatening information. Key points about habituation: Reduced response: As the stimulus is repeated, the response becomes weaker. This happens because the brain starts recognizing the stimulus as unimportant or not requiring attention. Learning without conscious effort: Habituation is a form of learning that occurs naturally without requiring any conscious effort. It helps save energy and focus by ignoring irrelevant stimuli. Examples: Background noise: If you live near a busy street, at first, the sound of traffic might be very noticeable. But over time, you stop noticing it because your brain has habituated to the noise. Clothing: When you first put on clothes, you can feel them on your skin. But after a while, you stop noticing the sensation because you’ve habituated to it. Biological Explanation: Habituation occurs at the synaptic level in the brain. The more a stimulus is presented, the less neurotransmitter is released by the neuron when that stimulus is encountered. This results in a weaker signal being sent to the brain, so the organism reacts less to the stimulus. Sensitization Increased response to repeated stimuli. Takes place in potassium channels, then calcium channels Sensitization is the opposite of habituation. It’s a process where an organism's response to a stimulus increases with repeated exposure, especially if the stimulus is intense or harmful. Essentially, instead of getting used to a stimulus and ignoring it (as in habituation), sensitization makes you more alert or reactive to the stimulus. Key points about sensitization: Increased response: With each exposure to the stimulus, the organism's reaction becomes stronger. Sensitization is most likely to occur when the stimulus is unexpected, intense, or associated with danger or pain. Adaptive function: Sensitization helps protect an organism by enhancing its ability to detect and respond to threats. The heightened response helps the organism prepare for potentially harmful or dangerous situations. Examples: Loud noises: If you're in a quiet room and a loud noise suddenly occurs, you might jump. If that loud noise keeps happening unpredictably, your reactions (like flinching or feeling anxious) might get stronger each time. Your brain becomes sensitized to the noise. Pain response: If you are repeatedly exposed to a painful stimulus, like a mild electric shock, your body may become more sensitive to it. The pain might feel worse each time it happens, even if the intensity of the stimulus doesn't change. Biological Explanation: Sensitization involves changes in the brain at the synaptic level, where certain neurotransmitters are released in higher amounts with each repeated exposure to the stimulus. For example, in sensitization, potassium (K⁺) channels in the neuron become less responsive, prolonging the action potential, which leads to more calcium (Ca²⁺) influx and thus more neurotransmitter release. This creates a stronger signal in the postsynaptic neuron, enhancing the organism's response to the stimulus. Brain Brain structure can change with experience, neural reorganization, and new neuron generation. Brain Plasticity Our nervous system is capable of changing depending to the environment (plasticity). The brain’s ability to reorganize itself, especially after damage or through learning new skills. Brain structure change with experience Damage sensory pathway or destruction of brain tissue can lead to neural reorganization Adult brain can generate new neurons Neural Reorganization The brain can adapt to damage by reorganizing its neural pathways. For instance, in blind people, the occipital lobe (which processes vision) may take on new roles, such as processing auditory information. Neural pathways are networks of neurons that are connected to transmit signals across different parts of the brain and body. These pathways allow communication between neurons to facilitate various functions like movement, sensation, thought, emotion, and learning. Notable Examples: Taxi drivers show enlargement of the hippocampus (involved in spatial memory). Musicians often have changes in the motor cortex due to years of practicing fine motor skills. Bilinguals: Enlarged parietal cortex due to language skills. Split-brain experiments: Showed how the brain hemispheres process information independently. Damage to the RIGHT parietal lobe Results in Hemineglect or Hemi-inattention: A disruption or decreased ability to look at something in the left field of vision They don't see anything from the left side of something, the brain is unable to process that information Split-Brain Studies and Corpus Callosum: Corpus Callosum: The corpus callosum is a bundle of nerve fibers that connects the left and right hemispheres of the brain. Its primary role is to allow communication between the two hemispheres, ensuring both sides can share information. Split-Brain Procedure: In split-brain surgery, the corpus callosum is severed to treat severe epilepsy, preventing seizures from spreading between hemispheres. However, this also prevents the two hemispheres from communicating effectively, leading to distinct behaviors when stimuli are presented to only one hemisphere. Michael Gazzaniga's Split-Brain Experiments: Visual Processing: Each hemisphere processes visual information from the opposite visual field. The left hemisphere controls language and speech, while the right hemisphere is involved in spatial and non-verbal tasks. In split-brain patients, when an object is shown in the right visual field (processed by the left hemisphere), the person can name the object. If the object is shown in the left visual field (processed by the right hemisphere), the person cannot name it but can draw or point to it. Classic Split-Brain Experiment: A spoon and fork are flashed briefly in different visual fields (spoon in the left, fork in the right). When asked, the person says they saw the fork (right visual field, processed by the language-dominant left hemisphere). However, when asked to pick up the object they saw with their left hand, they pick up the spoon (left visual field, processed by the right hemisphere). Real-life Effects: Left Hemisphere (Speech & Logic): Handles tasks requiring language, logic, and analytical thinking. Right Hemisphere (Non-verbal & Spatial): Deals with spatial recognition, face recognition, and visual imagery. Communication Breakdown: When the hemispheres can't share information, tasks that require integrating speech and spatial recognition become difficult. Interpretation: Split-brain patients offer insights into brain lateralization, demonstrating how specialized tasks are handled by different hemispheres. The left hemisphere is adept at verbal explanation, while the right hemisphere excels in non-verbal tasks. These experiments illustrate how the brain's ability to integrate information across hemispheres is crucial for cohesive thought and behavior. CHAPTER 4: Chapter 4: Consciousness - Key Notes 1. What is Consciousness? Consciousness: One's moment-to-moment subjective experience of the world. Definitions of Consciousness: Sensory Awareness: Knowledge of the environment through sensory perception. Direct Inner Awareness: Knowledge of one's own thoughts and feelings without using the senses. Personal Unity: The sense of self, your identity formed from thoughts and feelings. Waking State: The state of being awake and aware of internal and external experiences. 2. Attention as the Gateway to Consciousness Attention is crucial for consciousness. Without it, we are not fully aware of what's happening. Change Blindness: Failing to notice large changes in the environment when attention is elsewhere (e.g., Stranger and the Door study). Inattentional Blindness: Failing to notice an obvious object in the visual field when attention is focused on something else (e.g., Invisible Gorilla experiment). 3. Types of Attention Exogenous Attention: Automatic, stimulus-driven attention. Captured by external events (e.g., loud noises). Endogenous Attention: Voluntary, goal-driven attention. Focused on tasks you're consciously engaging in (e.g., reading a book in a noisy environment). 4. Dichotic Listening and Change Deafness Dichotic Listening Task: Participants are presented with different audio messages in each ear and asked to focus on only one. Change Deafness: Participants notice physical changes (e.g., change in speaker's voice) but often miss semantic changes (e.g., change in language). Selective Attention: We can focus on one stream of information while ignoring others, but only to a certain extent. 5. The Stroop Effect Stroop Effect: A phenomenon where the brain’s automatic processing of word meanings (semantic information) interferes with identifying the color of the ink (sensory information). Example: When "RED" is printed in blue ink, participants are slower to name the ink color because they automatically read the word's meaning. 6. Divided Attention and Dual Processing Dual Processing: Performing two tasks simultaneously. If both tasks are easy, you can perform well. If both are difficult, performance declines. Divided Attention: Trying to focus on multiple tasks at once. True multitasking is hard for the brain when both tasks require effort (e.g., listening to a lecture while taking notes). 7. Hemineglect Hemineglect: A disorder where individuals ignore one side of their visual field, often due to damage in the right parietal lobe. This affects attention, not vision. Examples: Patients may eat only from one side of a plate or shave only one side of their face. In memory tasks, they may describe only the right side of a familiar location. 8. Brain Waves and Consciousness States Gamma Waves: Problem solving, concentration (not related to sleep) Beta Waves (12-30 Hz): Alert, awake state. Associated with active thinking, focus, and problem-solving. Alpha Waves (7.5-12 Hz): Relaxed, calm state (e.g., eyes closed but awake). Theta Waves (4-7.5 Hz): Light sleep or deep meditation. Associated with creativity and visualization. Delta Waves (up to 4 Hz): Deep sleep, where restorative processes occur. 9. Sleep Stages and Brain Activity Stage 1: Light sleep; theta waves. Transition between wakefulness and sleep. Stage 2: Deeper sleep; characterized by sleep spindles and K-complexes. Helps maintain sleep despite external disturbances. Stage 3 & 4: Deep sleep; delta waves dominate. This is essential for physical restoration and immune function. REM Sleep: Rapid Eye Movement sleep. Brain activity is similar to when awake, but the body is paralyzed. Dreams mostly occur in this stage. Sleep Cycles: A 90-minute cycle where deep sleep occurs earlier in the night, and REM sleep becomes more frequent towards morning. 10. REM vs. NREM Sleep Across Ages Infants: Spend more time in REM and NREM sleep (around 16 hours a day). REM helps with brain development. Adults: Sleep 7-8 hours, with about 20-25% of that time in REM sleep. NREM dominates the rest. Elderly: Sleep less, with reduced REM sleep and overall lighter sleep. 11. Altered States of Consciousness Meditation: Shifting focus inward, leading to altered perception and relaxation. Hypnosis: A highly focused, suggestible state where perception and behavior can be altered. Psychoactive Drugs: Substances that alter sensory perception, mood, and thought patterns (e.g., hallucinations, altered awareness). Sleep: A naturally occurring altered state with distinct stages, each associated with different brain wave patterns. 12. Key Sleep Terminology K-Complex: A large wave in stage 2 sleep that helps protect the sleeper from waking due to external stimuli. Sleep Spindle: A burst of brain activity in stage 2 sleep, thought to help with memory consolidation. Sleep Cycles: Each cycle lasts about 90 minutes, alternating between REM and NREM stages. Deep Sleep: Mostly in the first half of the night, vital for physical restoration. REM Sleep: Increases toward morning, important for mental and emotional recovery. 13. Visual Search: Conjunction vs. Disjunction Conjunction Search: Slower, uses serial search, more difficult with increasing distractors. Disjunction Search: Faster, uses parallel search, unaffected by distractors. Key Question: Why is conjunction search slower than disjunction search? 14. Cocktail Party Effect Definition: Ability to focus on a specific conversation in a noisy environment while filtering out background noise. Example: Hearing your name across a room despite being focused on another conversation. Key Question: How does the cocktail party effect demonstrate selective attention?