Pcych 1010 Neuron and Nerotr

Study Notes on Neurons and Neurotransmission

Overview of the Lecture

• This document does not serve as a comprehensive outline but provides a guide for organizing concepts related to neuron structure and function. It is important to utilize this guide effectively to avoid confusion.

Localization

• Refers to the specific locations and functions of neural components within the nervous system.
• Key terms:
  • Gall - Possibly referring to Franz Joseph Gall, known for creating the theory of phrenology, linking brain areas to personality traits.
  • Gage - Possibly referring to Phineas Gage, whose accident provided critical insights on the role of the frontal lobe.

Neurons

• The fundamental building blocks of the nervous system, responsible for receiving, processing, and transmitting information.

Types of Neurons

• Sensory Neurons: Transmit sensory information from receptors to the central nervous system (CNS).
• Motor Neurons: Convey commands from the CNS to muscles and glands.
• Interneurons: Function as connectors between sensory and motor neurons within the CNS.

Neuron Structure

• Each neuron consists of several key components:
  • Dendrites: Branch-like structures that receive signals from other neurons.
  • Soma (Cell Body): Contains the nucleus and organelles, integrating signals received from dendrites.
  • Nucleus: The control center containing the neuron's genetic material.
  • Axon: A long extension that transmits electrical impulses away from the soma.
  • Myelin Sheath: Fatty layer that encases the axon, facilitating faster signal transmission through insulation.
  • Terminal Buttons: Structures located at the end of the axon that release neurotransmitters into the synaptic cleft.

Messages in Neurons

• Neurons convey messages both within and between themselves.

Within Neuron Messaging

• Electrical impulses (Action Potentials) that travel from the dendrites to the terminal buttons through the axon.

Between Neurons Messaging

• Requires neurotransmitters that cross the synapse to transmit messages to adjacent neurons.

Action Potential

• Definition: A rapid rise and fall in membrane potential that triggers neuron firing.
  • Excitatory influences increase the likelihood of neuron firing.
  • Inhibitory influences decrease the likelihood of neuron firing.
• Net Potential: The overall effect of excitatory and inhibitory inputs.
  • If net potential is greater than a specific threshold, the neuron fires an action potential.
  • If the net potential is below threshold, the neuron will not fire.

Stimuli Intensity

• Neurons respond to stimuli with varying intensities, leading to a graded response in action potentials, depending on the intensity of stimulation.

Neurotransmitters

• Chemical messengers that transmit signals across a synapse from one neuron to another.

Types of Neurotransmitter Actions

• Agonists: Substances that enhance or mimic the action of neurotransmitters.
• Antagonists: Substances that inhibit or block the action of neurotransmitters.

Neural Plasticity

• The ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli, and is essential for learning and adaptation.

Aspects of Neural Plasticity

• Development: Growth of neural pathways during early brain development.
  • Synaptogenesis: Formation of new synapses.
  • Pruning: Elimination of excess synapses to improve efficiency.
  • Myelination: Development of myelin around axons for improved signal transmission.

Learning and Adaptation

• Neural plasticity enables organisms to adapt based on experiences, facilitating learning and memory.

Injury and Degeneration

• Neural plasticity plays a role in recovery from injuries and various degenerative conditions affecting the nervous system.
  • Neural Degeneration: Loss of structure or function of neurons due to injury or disease.
• Adaptations may occur through the reorganization of neural pathways following injury, underscoring the resilience of neural systems.