Neuroanatomy and Neural Activity PDF

Part 1: Neuroanatomy Key Brain Structures and Functions: ​ Cerebellum – Coordination of movement and balance ​ Pons ​ Thalamus – Sensory relay station, processing and transmitting information ​ Hypothalamus – Regulates homeostasis, hunger, thirst, and the endocrine system...

Part 1: Neuroanatomy Key Brain Structures and Functions: ​ Cerebellum – Coordination of movement and balance ​ Pons ​ Thalamus – Sensory relay station, processing and transmitting information ​ Hypothalamus – Regulates homeostasis, hunger, thirst, and the endocrine system ​ Pituitary gland ​ Corpus callosum – Connects the two hemispheres, facilitating communication ​ Cingulate cortex ​ Occipital lobe – Vision processing ​ Temporal lobe – Auditory processing, memory, and language comprehension ​ Parietal lobe – Sensory processing and spatial awareness ​ Frontal lobe – Decision-making, problem-solving, motor function Key Landmarks and Structures: ​ Central fissure ​ Precentral gyrus – Primary motor cortex, controls voluntary movements ​ Postcentral gyrus – Primary somatosensory cortex, processes touch ​ Lateral fissure ​ Longitudinal fissure ​ Superior temporal gyrus ​ Caudate nucleus (head & tail) ​ Basal ganglia – Motor control and learning ​ Limbic system – Emotion, motivation, and memory (includes hippocampus, amygdala, fornix) ​ Hippocampus – Learning and memory ​ Amygdala – Emotion processing, particularly fear ​ Superior colliculus ​ Inferior colliculus ​ Optic chiasm ​ Fornix ​ Ventricles (Lateral & Third) Neuron Structures: ​ Soma – Cell body, contains the nucleus ​ Dendrites – Receive incoming signals ​ Axon initial segment – Generates action potential ​ Axon – Transmits electrical impulses ​ Myelin – Insulates axon, speeds up signal transmission ​ Terminal buttons – Release neurotransmitters ​ Synaptic cleft – Gap where neurotransmitters transfer signals Part 2: Neural Activity Action Potential and Synaptic Transmission: ​ Presynaptic neuron – Sends signal ​ Postsynaptic neuron – Receives signal ​ EPSP (Excitatory Postsynaptic Potential) – Depolarizes membrane, increasing likelihood of firing ​ IPSP (Inhibitory Postsynaptic Potential) – Hyperpolarizes membrane, decreasing likelihood of firing ​ Axon initial segment – Where action potential starts if threshold is met ​ Threshold of excitation – Minimum voltage to trigger an action potential, -65mV ​ Action potential – Electrical impulse traveling down the axon ​ All-or-nothing principle – Action potential either occurs fully or not at all ​ Voltage-gated ion channels – Open or close in response to voltage changes ​ Terminal buttons – Release neurotransmitters into synaptic cleft ​ Synaptic vesicles – Store neurotransmitters ​ Neurotransmitter – Chemical messengers (e.g., dopamine, serotonin, glutamate) ​ Receptor – Binds neurotransmitter to trigger response ​ Ionotropic receptor – Directly opens ion channels ​ Metabotropic receptor – Triggers secondary messengers for slower response ​ Reuptake/recycling – Process of neurotransmitters being reabsorbed 1. Electrical Communication (Inside the Neuron) This happens within a neuron, traveling from the dendrites → cell body → axon → axon terminals. Key Structures: ​ Dendrites: Receive signals from other neurons. ​ Cell Body (Soma): Processes incoming signals. ​ Axon Hillock: Where the action potential starts if the signal is strong enough. ​ Axon: The long pathway that carries the action potential. ​ Myelin Sheath: Fatty covering that speeds up the signal. ​ Nodes of Ranvier: Gaps in myelin where the signal "jumps" to move faster. ​ Axon Terminals: The endpoint where the signal is sent to the next neuron. Steps: 1.​ Resting State (-70 mV) ○​ The neuron is at rest, with Na⁺ (sodium) outside and K⁺ (potassium) inside the cell. ○​ Maintained by the sodium-potassium pump. 2.​ Depolarization ○​ If the neuron gets enough input, the axon hillock opens voltage-gated Na⁺ channels. ○​ Na⁺ rushes in, making the inside positive (~+30 mV). 3.​ Repolarization ○​ K⁺ channels open, letting K⁺ out to restore negativity inside. 4.​ Hyperpolarization ○​ Too much K⁺ leaves, making the neuron extra negative. ○​ The sodium-potassium pump restores balance. 5.​ Propagation (Movement of the Signal) ○​ In myelinated neurons, the action potential "jumps" between Nodes of Ranvier, speeding up transmission (saltatory conduction). 2. Chemical Communication (Between Neurons) Synaptic Transmission This happens at the synapse, the tiny gap between neurons. Key Structures: ​ Axon Terminals (Presynaptic Neuron): The end of the neuron where signals are sent. ​ Synaptic Vesicles: Tiny sacs in the axon terminal filled with neurotransmitters. ​ Synaptic Cleft: The space between two neurons. ​ Receptors (Postsynaptic Neuron): Proteins on the next neuron that catch neurotransmitters. Steps: 1.​ Action Potential Reaches the Presynaptic Neuron ○​ This opens voltage-gated Ca²⁺ (calcium) channels. ○​ Ca²⁺ enters, triggering synaptic vesicles to release neurotransmitters. 2.​ Neurotransmitter Release ○​ Neurotransmitters (like dopamine or acetylcholine) cross the synaptic cleft. 3.​ Binding to the Next Neuron ○​ Neurotransmitters attach to receptors on the postsynaptic neuron. ○​ If enough binds, a new action potential starts in the next neuron. 4.​ Neurotransmitter Removal ○​ Enzymes break them down, or they are reabsorbed (reuptake) to stop the signal. Summary 1.​ Electrical Signal travels through the neuron (from dendrites to axon terminals). 2.​ Chemical Signal happens at the synapse, where neurotransmitters pass the message. 3.​ If strong enough, the next neuron fires a new action potential, continuing the signal. Part 3: Learning and Memory Long-Term Potentiation (LTP): is a process by which connections between neurons become stronger with frequent activation ​ Presynaptic neuron – Releases neurotransmitter ​ Postsynaptic neuron – Strengthens synapse with repeated stimulation ​ EPSP – Strengthens synapse by increasing response ​ NMDA receptor – Key receptor in synaptic plasticity, requires glutamate and depolarization ​ AMPA receptor – Facilitates fast synaptic transmission ​ Glutamate – Main excitatory neurotransmitter ​ Magnesium ion – Blocks NMDA receptors at rest ​ Calcium ions – Enter through NMDA receptors, triggering synaptic strengthening ​ Sodium ions – Enter through AMPA receptors, depolarizing the neuron ​ Efficiency – Enhanced synaptic transmission from repeated activation ​ Synapse – Site of learning and memory formation Study Strategies and Memory Enhancement How I Study for This Class To study for this class, I use a combination of active recall and spaced repetition to strengthen my understanding. I frequently test myself by using flash cards and space out my study sessions which work effectively. a. Two Different Types of Memory 1.​ Explicit Memory – conscious recall of facts and events. I use it when memorizing brain structures and their functions. 2.​ Implicit Memory – is used for skills and habits. It helps when I practice drawing neuroanatomy diagrams frequently. b. Two Factors That Enhance Memory 1.​ Active Recall 2.​ Spaced Repetition Strengths: very effective in enhancing memory Weakness: distracting because of the gap between the study sessions. c. Two Neural Structures Involved in Learning and Memory 1.​ Hippocampus – consolidation of new memories 2.​ Amygdala – emotional memory formation Case Study: H.M. a. Brain Area Removed ​ The medial temporal lobes, including the hippocampus and amygdala. b. Impaired Types of Memory ​ Anterograde explicit memory c. Intact Types of Memory ​ Implicit Memory ​ Short Term Memory d. Tests Measuring Memory Performance 1.​ Mirror Drawing Task — Tested implicit memory 2.​ Digit Span Task – Tested working memory 3.​ Recall Tests – Tested explicit memory