Biology and Neuroscience PDF

Chapter 3 – Biology and Neuroscience 3.1 Introduction: The Smart Conduit Nervous system --> main interpreter of the events in your body and those in the outer world. Brain and spinal cord --> ultimate problem solvers (send and receive information to and from all are...

Chapter 3 – Biology and Neuroscience 3.1 Introduction: The Smart Conduit Nervous system --> main interpreter of the events in your body and those in the outer world. Brain and spinal cord --> ultimate problem solvers (send and receive information to and from all are Nervous system is a maze of complex cellular networks that relay and process information. (Its over It helps you to make sense of the things around you and make decisions about what to do next. This integrated set of networks is composed of specialized cells called neurons (cells that transmit e provide support functions. These cells are arranged in all kinds of different configurations to perform dedicated tasks. neural --> “relating to the nerve or nervous system.” Neural networks --> help us communicate with one another through movement and sound. Each person’s nervous system is made unique by their experiences. 3.2.1.2 The Soma and Axon Work Together to Send Messages Dendrites --> extensions of the membrane of the soma, or cell body. The soma --> the location of metabolic processing in the cell and contains the cell's organelles. Axon hillock (Protruding from the cell membrane) --> the beginning of the axon. Neurons have many dendrites that branch out from the soma; however, there is only one axon. The axon acts much like a wire, transmitting the signal from the soma to the end of the axon, where terminals and terminal buttons (sometimes called synaptic knobs). The terminal buttons --> important role in neural communication. This terminal button houses vesicles --> little bubbles containing the neurotransmitters. At the terminal buttons the neuron will release neurotransmitters, sending the signal to other near This portion of the cell sends signals into the space between neurons, it is also called the presynap The vesicles release their contents into the synaptic cleft (the space between two neurons --> usu The synapse --> connection between two neurons that allows them to communicate. Once neurotransmitters are released from the vesicles --> float in the synaptic cleft until they bind t dendrites of adjacent neurons, are recycled, or degraded. EX: Iron Man: Energy is generated in the body of the suit (the soma) and travels down the arms of h When the energy reaches his gloved fingers (the axon terminals), a jolt is released from the tips of h Nervous system is a network. Whole sequence occurring trillions of times through 80–90 billion neurons that are arranged to connect w configurations. Each communication between neurons occurs within about 5 milliseconds --> simultaneously or in rapid s Another feature of some axons --> protein and fatty substance called myelin This substance acts kind like --> insulation wrapped around the wires you use every day to plug things into electrical impulse flowing down the axon.) There are also breaks in the myelin --> Nodes of Ranvier The nodes play an important role in helping the signal to travel down the axon by allowing ions to enter an eas of your body) rall purpose is to create behavior). electrical impulses) and glial cells that e you will find the axon rby dendrites. ptic neuron. ually the axon and the dendrite) to postsynaptic receptors on the his suit (the axon). his fingers (the terminal buttons). with each other in different succession trillions of times a day. o the wall (or your phone). (keeps the nd change the charge inside the cell.  configurations. Each communication between neurons occurs within about 5 milliseconds --> simultaneously or in rapid s Another feature of some axons --> protein and fatty substance called myelin This substance acts kind like --> insulation wrapped around the wires you use every day to plug things into electrical impulse flowing down the axon.) There are also breaks in the myelin --> Nodes of Ranvier The nodes play an important role in helping the signal to travel down the axon by allowing ions to enter an This allows for more efficient signal transmission. The structures in the neuron are optimized to transform and transfer energy, and send chemical messages 3.2.2 How Neurons Transmit Messages: More Detail on the Action Potential - Neurons share information within/between parts of the nervous system --> there must be control of when - The main way this sharing of messages happens is through a burst of electrical energy in the neuron that s (This can either be triggered or shut down.) - Electrically charged particles in our bodies called ions --> Electrical activity in the body exists because of th - Basic ions: sodium (Na+) , chloride (Cl–) (the particles that make up table salt) (Sodium --> positive charge, Positively charged Potassium (K+)) - A large number of negatively charged ions inside the cell causes the neuron to have a negative charge, usu Called --> "polarized" because the charge is far away from 0, which is neutral. - When the cell is polarized --> at rest and will not release neurotransmitters. - The more positively charged particles inside the cell, the more positive the charge inside that cell will be. - are moving away from the state of being polarized. - The more depolarized the neuron is, the more likely it is to activate (action potential) and send a neurotra organs. - Ex: if we bring Na+ into the cell, it gets closer to the action potential --> If we push K+ out of the cell, it gets the positive ions makes the neuron more negative (polarized). - A neuron has a membrane barrier keeping things from getting in or out. --> several kinds of doors (chann Some are locked and need a special key, like a neurotransmitter, and some are waiting for a stimulus or the cell - Opening each of the channels changes something different inside the cell. - The action potential can be produced by the movement of Na+ into the neuron through a specific set of ch - EX: Imagine a nightclub with Na+ ions as party people. There is only one door (channel) open because ther ions). If enough come in, you say “let’s open all the doors and rooms for more party people (more Na+ ion do. They are waiting to see how many positive ions show up, to see if there is enough excitement to open climax, this is the action potential. - There are multiple Na+ channels lined up strategically along the axon - this process causes the electrical im the axon (see in pic). - As the gated channels in each successive section “sense” the positive shift in voltage, they pop open too, r propagation: the process by which electrical impulses get sent to the end of a neuron. - When this electrical impulse gets to the axon terminal, it triggers the release of neurotransmitters - In a normally functioning neuron, the opening of the K+ channels allows the neuron to return to and main - When its channel opens, K+ will rush out instead of in like Na+ succession trillions of times a day. o the wall (or your phone). (keeps the nd change the charge inside the cell. s, at specific times. n and how this happens. signals it to release a neurotransmitter. he movement of these charged particles. and chloride --> negative charge. ually around -70 millivolts (mV). --> called "depolarization" because we ansmitter to message other neurons or s closer to deactivating because losing nels) that open in different ways. --> r the charge (voltage) to change inside hannels at the right time. re are only a few party people (Na+ ns).” This is what voltage-gated channels n up more. When the party hits the mpulse to continue in succession along repeating the rush of Na+. --> ntain resting potential. - As the gated channels in each successive section “sense” the positive shift in voltage, they pop open too, r propagation: the process by which electrical impulses get sent to the end of a neuron. - When this electrical impulse gets to the axon terminal, it triggers the release of neurotransmitters - In a normally functioning neuron, the opening of the K+ channels allows the neuron to return to and main - When its channel opens, K+ will rush out instead of in like Na+ - Potassium channels respond to depolarization as well, but after the Na+ channels do (Na+ coming in trigge - Results in quick repolarization of the neuron to negative resting potential. - This resets” the neuron so that it can be activated again. Steps of Action Potential Step Explanation Step 1: Threshold The amount of voltage change required to trigger the opening of voltage-gated caused by Na+ entering the cell. Step 2: Depolarization After the threshold is met, the voltage-gated channels open. This increase posit inside of the cell to become less negative/polarized compared to the outside (th polarized). Occurs along the axon. A myelinated cell --> occurs the exposed area Ranvier. Step 3: Repolarization The Na+ channels close and trigger the opening of passive potassium (K+) chann voltage-gated channels allow K+ to leave the cell. The opening of the Na+ chann become more postively charged and the decrease of other positive ions allow th relatiely negative compared to surrounding fluid. repeating the rush of Na+. --> ntain resting potential. ers K+ leaving). channels in the cell. This is tive ions in the cell, cause the he cell is becoming de- a of the axon, the nodes of nels. Both passive and nels caused the cell to he cell to once again be  Step 3: Repolarization The Na+ channels close and trigger the opening of passive potassium (K+) chann voltage-gated channels allow K+ to leave the cell. The opening of the Na+ chann become more postively charged and the decrease of other positive ions allow th relatiely negative compared to surrounding fluid. Step 4: Refractory Period (Might not need to know this) Step 5: Resting State The neuron stabilizes and returns to its resting state potential 3.2.3 How Neurotransmitters and Receptors Work - Neurotransmitters --> The chemicals released from axon terminals that then bind with receptors on anoth - Neurotransmitters can be excitatory --> they increase the probability of the neuron becoming electrically - Neurotransmitters can be inhibitory --> they decrease the probability that the neuron is activated - In the example: The axon of the first (presynaptic, or sending) neuron releases neurotransmitters from its neurotransmitters enter the synaptic space, they are attracted to receptors on the dendrites of the second where they alter cellular activity, If enough neurotransmitters activate their receptors --> we can get an ac - A neuron may receive inputs from both excitatory and inhibitory neurotransmitters. - Channels have gates that are like locks - The interaction of each neurotransmitter with a receptor produces a different kind of response in the neu - Some interactions are inhibitory (causing hyperpolarization, –) and others are excitatory (causing +). - EX: GABA (inhibitory neurotransmitter) binds with its receptor to open a chloride (Cl–) channel. - This makes the cell negative, which as we know means the cell is more likely to be inactivated (inhibited). nels. Both passive and nels caused the cell to he cell to once again be her neuron active. vesicles , When these d (postsynaptic, or receiving) neuron, ction potential - uron. - - Channels have gates that are like locks - The interaction of each neurotransmitter with a receptor produces a different kind of response in the neu - Some interactions are inhibitory (causing hyperpolarization, –) and others are excitatory (causing +). - EX: GABA (inhibitory neurotransmitter) binds with its receptor to open a chloride (Cl–) channel. - This makes the cell negative, which as we know means the cell is more likely to be inactivated (inhibited). - Acetylcholine (Ach) --> excitatory neurotransmitter. - When it binds to its appropriate receptor, a sodium (Na+) channel is opened, making the cell more positive - Factors influence what kinds of behaviors, feelings, or thoughts result from neurotransmitter release (the are being released in the brain, the timing of the release, and the activity of other neurons in the same ne 3.3 Brain Anatomy: How to Build a Sophisticated Network - Neural networks --> complex connections between the dendrites and axons of many neurons. - A nerve --> a large bundle of axons from many neurons bundled into a tube that extends a large distance. - These axons extend from cell bodies that are housed in the central nervous system (consists of the brain a - Some Axons (Efferents) are carrying electrical impulses away from the CNS to trigger neurotransmitter/ho - Afferents --> are carrying impulses back to the CNS from the organs and muscles. - Neuroplasticity --> the ability of neurons and their networks to change - Get rid of neurons that are inefficient, damaged, or unnecessary. - Nervous system can grow new branches on dendrites and change amounts of receptors and neurotransm neuroplasticity that changes how networks are organized) - Processes that occur in our brains/bodies are automatic (below the level of consciousness) (other neural n - Neocortex --> conscious thought/decision making --> outer layer of brain (The conscious processing of sen - Medulla --> basic life functions --> Circuits here (a structure in the brainstem) help control basic life-suppo and reflexes - Your heart will beat and your lungs will expand and contract without you needing to consciously send this - why some individuals in a comatose state can still breathe and pump blood through the heart (despite the or move.) (Even though the person is not conscious or active, the other networks responsible for maintain - The thoughts and fears we are fully aware of can shift, or modulate, the function of the heart and lungs. T - hink about things that calm us down or make us angry, and this will either slow down or speed up our hea - Stressful situations activate the same mechanisms that help us fight or flee when we are in danger. - This modulation of neural networks in the lower-brain centers like the medulla and spinal cord is made po cortex to connect with neurons in the medulla. 3.4.1 The Peripheral Nervous System: Bridge between Brain, Body, and World - Peripheral nervous system --> split into somatic (voluntary) and autonomic (automatic) divisions - Your vertebrae are individual joints that make up your vertebral column. - This allows for two things: - (a) the ability to flex (think bending over), extend (reaching high), and twist the spine; and - (b) space for peripheral nerves to exit the spinal cord so that they can connect and communicate with the  - uron. e receptors they bind with), where they etwork. and spinal cord.) ormone release in an organ or muscle. mitters (these processes are part of the networks dedicated to those tasks.) nsory input occurs here) ort functions like breathing, heart rate, s message. e fact that they can’t respond to others ning life functions continue to operate.) T artbeat. ossible by axons that extend from the e body. - Your vertebrae are individual joints that make up your vertebral column. - This allows for two things: - (a) the ability to flex (think bending over), extend (reaching high), and twist the spine; and - (b) space for peripheral nerves to exit the spinal cord so that they can connect and communicate with the 3.4.1.2 The Autonomic Nervous System: Automatic Movement - The autonomic nervous system regulates all the automatic functions that keep you alive, functional, and h - The autonomic system is divided into sympathetic and parasympathetic connections to organs and endocr - The neurons/nerves of the parasympathetic nervous system originate in lower brain and sacral spinal cord - When activated --> parasympathetic nerves transmit commands to your organs that help you recover, dig - When we stimulate sympathetic nerves --> heart rate and breathing increases. (also an inhibition of digest - If you have ever been in a situation where you were nervous or frightened, your sympathetic nervous syst supporting cells in the spinal cord) was activated. - While your sympathetic nervous system is activated, your parasympathetic system is deactivated. - Yoga/good meal will activate circuits in the parasympathetic nervous system (heart rate and respiration w routed to your digestive system.) - The parasympathetic nervous system helps us to rest, recover, and repair. - Sex stimulates both the sympathetic and parasympathetic divisions. - The excitement of attraction will activate the sympathetic nervous system, resulting in increased heart rat - Feel jittery from increased neural activation of our muscles. - The parasympathetic system increases blood flow to the genitals --> erection for both the male and femal 3.5.2.2 Coordinating Movement - The basal ganglia (telencephalon and diencephalon) --> interconnected groups of neurons that serve to m brain before they reach the spinal cord - Increased blood flow/electrical activity in this area when someone is initiating or terminating a movement - The basal ganglia --> several groups of neuronal circuits near the base of the brain that help to coordinate movements more automatic. (helps learn to make complex movements more automatic. - Consists of the dorsal striatum (caudate nucleus and putamen) and ventral striatum (nucleus accumbens system.), the globus pallidus, the substantia nigra (send inhibitory outputs to the thalamus to help integr motor planning), and the subthalamic nucleus. e body. healthy. rine system structures d. gest, and become sexually aroused. tive activity) tem (mainly consisting of neurons and will slow down, and more blood will be te and respiration. le. modulate movement commands in the t (starting to walk, then stopping). e movement and assist in making --> synapse with axons from the limbic rate sensory and motor information with - The basal ganglia --> several groups of neuronal circuits near the base of the brain that help to coordinate movements more automatic. (helps learn to make complex movements more automatic. - Consists of the dorsal striatum (caudate nucleus and putamen) and ventral striatum (nucleus accumbens system.), the globus pallidus, the substantia nigra (send inhibitory outputs to the thalamus to help integr motor planning), and the subthalamic nucleus. - The striatum is where inputs to the basal ganglia come in. - Receiving inputs from all over the cortex helps basal ganglia coordinate multiple streams of info - How the basal ganglia and nuclei work together to help us learn movements through practice. - The basal ganglia have two circuits that process input and coordinate output. - Direct pathway --> has an excitatory effect on the thalamus and drives motor behavior. (facilitates the act appropriate for the present situation. ) - Indirect pathway --> has a net inhibitory effect on its targets. (helps the basal ganglia shut down motor p task at hand.) - These basal ganglia lint to the development and progression of Parkinson’s disease (a progressive disease - Parkinson’s patients exhibit a symptom called “cogwheel rigidity.” (This means that the patient will have a movements.) - The cerebellum is the part of your brain is basically a rhythm and timing machine. - The neuronal circuits in the layers of the cerebellum are connected with other parts of the brain to modify movement/cognitive tasks. - Circuits in the cerebellum set up to simultaneously receive and organize input from multiple central nervo - The cerebellum is separated into three major divisions: spinocerebellar (helps to match sensory input with movement patterns), vestibulocerebellar ( processes information from the inner ear to help adjust your p and cerebrocerebellar (lateral hemispheres and dentate nuclei) manages connections with the pons and planning of movements. 3.5.3 Neocortex (New Brain): Higher-Level Processing - Human Brain Differences from Other Primates: - Number of connections in the neocortex and the size of the frontal lobes, which govern personality, conte - Neocortex Structure: - Wrinkled, "tree bark" part of the brain that most people think of when imagining the brain. e movement and assist in making --> synapse with axons from the limbic rate sensory and motor information with tivation of motor plans that are patterns/plans that are not right for the resulting in impaired movement. ) a hard time initiating and terminating y what they do, especially for ous system networks. h motor plans in order to fine-tune posture and balance) d thalamus to adjust the timing and ext, and decision-making.  3.5.3 Neocortex (New Brain): Higher-Level Processing - Human Brain Differences from Other Primates: - Number of connections in the neocortex and the size of the frontal lobes, which govern personality, conte - Neocortex Structure: - Wrinkled, "tree bark" part of the brain that most people think of when imagining the brain. - Made up of three features (gyri, sulci, and fissures), allows more brain tissue to fit inside the skull. - Has six layers. - Frontal Lobes: - Important for abstract thought and complex functions like decision-making and understanding context. - Neocortex Lobes: - Divided into four main lobes. - Each lobe has specialized functions but they all work together, with neurons connecting across lobes. - Primary and Association Areas: - Each lobe has primary areas that process sensory information. - Adjacent to these are the association cortex areas, which integrate and process information further. - EX: the smell of a grandparent's cooking combines sensory input with memories in these association areas 3.5.3.1 Frontal Lobes: Executive Decisions - Primary Functions: - The frontal lobes are crucial for decision-making and movement. - They help regulate behavior, control voluntary movements, and influence personality through neural inter - Executive Function: - Decision-making - A team effort across different brain regions, but an intact frontal lobe is necessary for maintaining behavio ext, and decision-making. s. ractions with the rest of the brain (CNS). oral and cognitive regulation. - A team effort across different brain regions, but an intact frontal lobe is necessary for maintaining behavio - Phineas Gage: - After a railroad accident, Phineas Gage's frontal lobe was damaged, leading to significant changes in beha - His case helped establish the link between the prefrontal cortex and personality - Motor Cortex: - The motor cortex in the frontal lobes controls voluntary movement through two pathways: Corticospinal tract: Controls body movements. Corticobulbar tract: Controls head and face movements. - Homunculus Concept: - Early researchers created a homunculus to represent how many neurons control each body part's movem more complex or delicate movements. However, modern research challenges the simplicity of this model - Prefrontal Cortex (PFC): The PFC integrates input from all cortical areas and plays a key role in higher-level decision-making houses about 14-17% of brain neurons and uses both inhibitory and excitatory connections to proc Dysfunction in the PFC is linked to negative symptoms in schizophrenia, such as social withdrawal. - Specialized Areas in PFC: Ventromedial PFC (vmPFC): Modulates behavior based on fear. Dorsolateral PFC (DLPFC): Helps maintain working memory and adjusts behavior for specific tasks, depending on context (e.g., hammering a nail while on a roof vs. indoors). - Myelination and Adolescence: - The PFC is one of the last brain regions to complete myelination, which explains the impulsiveness and la commonly seen in adolescents. However, individual variability exists in adolescent decision-making. - Implications for Personality Research: - The case of Phineas Gage and ongoing research suggest the prefrontal cortex is critical for understanding further explore how damage or dysfunction in the PFC affects personality traits.  oral and cognitive regulation. avior. ment. More neurons are dedicated to (e.g., "if this, then that" decisions). It cess information. such as modifying motor sequences ack of consideration for context personality. Future experiments could  commonly seen in adolescents. However, individual variability exists in adolescent decision-making. - Implications for Personality Research: - The case of Phineas Gage and ongoing research suggest the prefrontal cortex is critical for understanding further explore how damage or dysfunction in the PFC affects personality traits. 3.5.3.2 Parietal Lobes: Space, Time, and Numbers - Functions: - The parietal lobes are involved in processing numbers, calculations, and spatial awareness. - They help us understand where our body is in space and form mental representations of numbers. - Left vs. Right Parietal Lobes: - There are functional differences between the left and right parietal lobes: Right side damage can lead to impaired spatial navigation and difficulty interpreting sensations fro - Sensory Cortex: - The sensory cortex in the anterior (front) part of the parietal lobe receives sensory input from the contral - This happens because sensory and motor signals cross at the brainstem. - Cross-Lateral Movements: - The crossing of sensory and motor signals helps with coordinating both sides of the body, especially durin throwing a ball, eating, or dancing, where both sides of the body need to work together. - Brain Connections: - The parietal lobe integrates sensory information from the skin, muscles, and joints, and coordinates this w and thalamus 3.5.3.3 Temporal Lobes: Listen to the Memories - Location & Functions:  personality. Future experiments could om the left side of the body. lateral (opposite) side of the body. ng cross-lateral movements like with other brain areas via the brainstem  3.5.3.3 Temporal Lobes: Listen to the Memories - Location & Functions: - The temporal lobes are located above the ears and are involved in: Memory formation: Damage to this area, especially to the hippocampus, can lead to anterograde a memories cannot be formed (This is portrayed in the movie Memento.) Sound processing: The temporal lobes process sound information received from the auditory nerve auditory cortex can result in the inability to perceive sound, even though the ear and cochlear nerv - Wernicke’s Area: - Located in the left temporal lobe, this area is crucial for language processing. Damage here, such as from comprehend speech. - Olfactory & Taste Processing: - The temporal lobes also house areas for processing smell (olfaction) and taste: Smell: Unlike other senses, olfactory information bypasses the thalamus and goes directly to the te some animals’ survival and plays a key role in bonding (e.g., between mother and offspring) (Sanch Human Olfaction: While not as vital for humans as in other mammals, smell still plays a significant r design, which uses neuroscience to create attractive scents (Newson, n.d.). 3.5.3.4 Occipital Lobes: Visions of the Present - Human Visual Focus: - Humans rely heavily on vision, dedicating about a third of the brain to processing and interpreting visual in occipital lobes. - Occipital Lobes: - Primarily responsible for processing light stimuli rather than visual information as a whole. The brain interprets different wavelengths and intensities of light to create visual perception.  amnesia, a condition where new es. Extensive damage to the primary ve are intact. a stroke, can impair the ability to emporal lobes. Smell is essential for hez-Adrade, 2009). role, including in activities like perfume nformation, including areas like the  3.5.3.4 Occipital Lobes: Visions of the Present - Human Visual Focus: - Humans rely heavily on vision, dedicating about a third of the brain to processing and interpreting visual in occipital lobes. - Occipital Lobes: - Primarily responsible for processing light stimuli rather than visual information as a whole. - The brain interprets different wavelengths and intensities of light to create visual perception. - Optic Nerve Pathway: - The optic nerves originate in the retina and partially cross at the optic chiasma. - This ensures that visual information from the left visual field is processed in the right occipital lobe and vi Light from the left visual field activates the right retina and processes in the right thalamus and righ - Visual Field Integration: - The crossing of optic nerves helps the brain integrate visual information into a coherent image, linking eac the brain. - Specialized Neurons: - Some neurons in the occipital cortex respond specifically to certain features, such as object angles or posi - Damage to this area (from stroke, trauma, or seizure) can cause complete blindness or impair recognition - Brain Remapping: - In cases of blindness, the brain can remap and repurpose other senses, such as sound, to compensate for individuals report "seeing - " the world through sound. - nformation, including areas like the ice versa: ht occipital cortex. ch eye’s input to the opposite side of itions. of specific visual stimuli, like faces. the loss of vision. Some blind