Neuroscience and Behaviour Study Guide PDF

NEUROSCIENCE AND BEHAVIOUR Nervous System Overview Peripheral Nervous System (PNS) The PNS consists of cranial and spinal nerves that extend throughout the body, connecting the central nervous system to limbs and organs. Divisions of the PNS: ○ Autonomic Nervous System (AN...

NEUROSCIENCE AND BEHAVIOUR Nervous System Overview Peripheral Nervous System (PNS) The PNS consists of cranial and spinal nerves that extend throughout the body, connecting the central nervous system to limbs and organs. Divisions of the PNS: ○ Autonomic Nervous System (ANS): This system manages involuntary body functions such as heart rate and digestion, maintaining homeostasis. ○ Sympathetic Nervous System: Prepares the body for stressful or emergency situations (fight-or-flight responses), increasing heart rate and redirecting blood flow to muscles. ○ Parasympathetic Nervous System: Counteracts the sympathetic division, controlling bodily functions during rest and digestion (rest-and-digest response). ○ Enteric Nervous System: Often referred to as the "second brain," it controls the gastrointestinal system, regulating digestion and gut health. ○ Somatic Nervous System: Governs voluntary muscle movements, allowing interaction with the environment. Central Nervous System (CNS) The CNS is composed of the brain and spinal cord, acting as the main processing center for information and coordination of bodily functions. The Brain Neurons (Nerve Cells) Neurons are the fundamental units of the nervous system that transmit information throughout the body. ○ Components: ○ Soma (Cell Body): Contains the nucleus, which houses genetic material, and integrates synaptic signals from other neurons. ○ Dendrites: Tree-like structures that receive signals and information from other neurons' axon terminals. ○ Axon: A long projection that transmits electrical impulses away from the neuron. Axons can be myelinated (with an insulating layer enhancing signal transmission speed) or unmyelinated. Humans possess approximately 67-86 billion neurons and about 40-50 billion supportive glial cells, which play a role in maintaining homeostasis in the nervous system. The Parts of a Neuron  Axon Terminals: The branching end of an axon that connects with other neurons and releases neurotransmitters into the synapse. Synaptic Vesicles: Small sacs that contain neurotransmitters, essential for communication between neurons. Synaptic Cleft: The microscopic gap between pre-synaptic and post-synaptic neurons where neurotransmitter release and binding occur. Neuron Types: Unipolar Neurons: Typically found in invertebrates; have a single extension that branches into two functions (input and output). Bipolar Neurons: Found in sensory systems, such as the retina; have one axon and one dendrite. Multipolar Neurons: Commonly found in the spinal cord and brain regions, possessing many dendrites, facilitating complex communication. The Neural Impulse Stages of Action Potential: 1. Resting State: The neuron's membrane is polarized, with a potential of around -70 mV. 2. Depolarization: Occurs when sodium ions enter the neuron, making the interior less negative and reaching approximately +30 mV. 3. Repolarization: The neuron returns to its resting state as potassium ions exit. 4. Refractory Periods: Includes: Absolute Refractory Period: No new action potentials can occur regardless of stimulus strength. Relative Refractory Period: A stronger-than-normal stimulus is necessary to elicit a response. Neurotransmitter Function Presynaptic Processes: Involves the synthesis, storage, and release of neurotransmitters into the synaptic cleft. Binding: Neurotransmitters bind to specific receptors on the postsynaptic neuron, resulting in either excitatory or inhibitory signals that influence neuronal firing. Excitatory Postsynaptic Potential (EPSP): A positive voltage change that increases the likelihood of firing action potentials, leading to neural activation. Types of Neurotransmitters 1. Small-Molecule Neurotransmitters: Amino Acids: Includes Glutamate (excitatory) and GABA (inhibitory). Monoamines: Comprises dopamine, serotonin, and norepinephrine, each with distinct roles in mood and behavior.  Unconventional neurotransmitters: Such as Anandamide, which has effects similar to THC, the active component of cannabis. 2. Large-Molecule Neurotransmitters: Include neuropeptides like endorphins, which modulate pain and stress responses. Neurotransmitter Roles Acetylcholine (ACh): Crucial for muscle control, arousal, and cognitive functions. ACh dysfunction is implicated in Alzheimer's disease. Dopamine: Plays a significant role in reward pathways and motor control; its dysregulation is associated with Parkinson's disease and addiction. Serotonin: Linked to mood regulation, sleep, and appetite; a target for many antidepressant medications. Norepinephrine: Affects mood, arousal, and regulation of stress responses, functioning both as a neurotransmitter and hormone. The Limbic System The limbic system integrates emotional responses, memory formation, and homeostatic regulation of bodily functions. Key structures include: ○ Hippocampus: Essential for forming new memories and learning information. ○ Amygdala: Central to fear and pleasure responses, and emotional memory. ○ Hypothalamus: Regulates essential bodily functions like temperature, hunger, thirst, and circadian rhythms, linking the nervous system to the endocrine system. Cerebral Cortex Functions The cerebral cortex is divided into lobes, each responsible for different functions: ○ Frontal Lobe: Involved in higher cognitive processes such as reasoning, problem-solving, and movement. ○ Parietal Lobe: Processes sensory information including touch, temperature, and pain; important for spatial awareness. ○ Temporal Lobe: Manages auditory information and is involved in memory formation. ○ Occipital Lobe: Primarily responsible for processing visual information and interpreting visual stimuli. Neuroplasticity Neural Plasticity: Refers to the brain's ability to reorganize itself by forming new neural connections throughout life. This adaptability is critical during developmental stages and in response to learning experiences. In cases of brain injury, neural plasticity allows other regions to compensate and take over lost functions, demonstrating the brain's resilience. Brain Imaging Techniques Various techniques are employed to visualize brain structure and function: ○ Electroencephalography (EEG): Measures electrical activity in the brain, useful for diagnosing sleep disorders and seizures. ○ Magnetic Resonance Imaging (MRI): Provides detailed structural images of brain tissues, aiding in the diagnosis of abnormalities. ○ Positron Emission Tomography (PET): Visualizes metabolic processes and brain activity by injecting radioactive tracers, revealing functional aspects. ○ Functional MRI (fMRI): Monitors brain activity by detecting blood flow changes (BOLD response), allowing researchers to see brain activity in real time. ○ Transcranial Magnetic Stimulation (TMS): A non-invasive method that stimulates specific brain regions to investigate their functions and treatment potentials.