Neuroscience module 1

epigenetic modifications

changes made to DNA and chromatin that do not modify DNA sequences but can alter gene expression- these include DNA methylation and various modifications of histones (protein component of chromatin)

fixed action patterns

innate behaviors that occur in response to specific stimuli, executed in a predictable sequence and consistently performed the same way.

releasers

The essential features of the stimulus that activates the fixed action pattern

neural plasticity

changes in the nervous system in response to experience and learning

Neural plasticity

changes in the nervous system in response to experience and learning

Do adults or juveniles show higher neural plasticity?

juveniles show higher neural plasticity than adults, allowing for more significant adaptation and learning.

central nervous system

the part of the nervous system that includes the brain and spinal cord, responsible for processing information and coordinating activity.

peripheral nervous system

the part of the nervous system that connects the central nervous system to the limbs and organs, facilitating communication between the two.

Neurons

transmit electrical signals.

Glia

support and insulate neurons

Soma

the cell body of a neuron, containing the nucleus and organelles essential for its functioning.

Axon

Sends output, often myelinated. a long, slender projection of a neuron that conducts electrical impulses away from the cell body towards other neurons or muscles.

dendrites

receive input, may have dendritic spines. Short, branching projections that receive signals from other neurons.

presynaptic terminals

• Release neurotransmitters.

• specialized structures that participate in the transfer of information between neurons

• the specialized endings of axons that release neurotransmitters into the synapse, facilitating communication between neurons.

neurotransmitters

Chemical messengers released at synapses that transmit signals from one neuron to another, influencing various brain functions and processes.

Oligodendrocytes

• CNS

• form myelin sheaths for rapid conduction

• Glial cells in the central nervous system that provide support and insulation to axons by forming myelin sheaths, enhancing the speed of electrical signals.

Schwann cells

• PNS

• form myelin sheaths for rapid conductio

• Glial cells in the peripheral nervous system that form myelin sheaths around axons, aiding in the rapid conduction of electrical signals.

dendritic spines

Dendrites of many vertebrate neurons are decorated with small protrusions called dendritic spines, which likewise function in intercellular information transfer.

astrocytes

• present in the grey matter of the CNS

• Play many roles in neural development and regulation of neuronal communication

• Star-shaped glial cells in the central nervous system that provide structural support, transport nutrients, and maintain the blood-brain barrier, playing a crucial role in neurotransmitter regulation and neuronal health.

microglia

• Immune cells of the CNS

• Involved in maintenance and response to injury

reticular theory

• believed that the reticulum as a whole, rather than its individual cells, constituted the unit of the nervous system.

• A historical hypothesis in neuroscience that proposes that the nervous system is made up of a continuous network of interconnected neurons, rather than being composed of discrete cells.

neuron doctrine

• postulated that neuronal processes do not fuse to form a continuous reticulum.

• The neuron doctrine is the fundamental concept in neuroscience that states that neurons are the basic structural and functional units of the nervous system. It asserts that individual neurons communicate with each other through synapses and are distinct entities, contrary to the earlier reticular theory.

synapse

• The term synapse was later coined by Charles Sherrington to describe these sites, at which signals flow from one neuron to another.

• A junction between two neurons where neurotransmitters are released.

golgi stain

 random neurons stained black, revealing full morphology.

Camillo Golgi

discovered the method, supported the reticular theory.

Santiago Ramón y Cajal

used Golgi stain to support the neuron doctrine (neurons are discrete units).

theory of Dynamic Polarization (Ramón y Cajal)

Signal flows: Dendrite → Soma → Axon.

Pyramidal neurons

apical + basal dendrites, found in cortex.

Basket cells

inhibitory; axons wrap around other cells.

Motor neurons

bushy dendrites, long axon to muscle

Sensory neurons

pseudounipolar; axon splits into central and peripheral branches.

Invertebrate neurons:

often unipolar, branches mix input/output roles

Axon Initial Segment

Site of action potential initiation.

membrane potential

difference in charge across cell membrane.