Neuroscience Chapter on Neuron Function

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Questions and Answers

What occurs during the depolarization phase of a neuron?

The neuron's voltage remains unchanged.

Positive ions rush into the cell. (correct)

Negative ions leave the cell.

The neuron starts its refractory period.

What is the role of neurotransmitters in neuron communication?

They block receptor sites in the receiving neuron.

They absorb excess ions from the synapse.

They travel between neurons to facilitate signaling. (correct)

They create action potentials in the sending neuron.

What is the main difference between agonists and antagonists?

Agonists mimic neurotransmitters, while antagonists inhibit their action. (correct)

Agonists block neurotransmitter action, while antagonists enhance it.

Agonists slow down neuron firing, while antagonists speed it up.

Agonists work only in synaptic gaps, while antagonists act within the neuron.

What is the primary reason a neuron cannot fire again during the refractory period?

The voltage is too negative for firing. Signup and view all the answers

How does reuptake affect neurotransmitter levels in the synapse?

It reabsorbs excess neurotransmitters into the sending neuron. Signup and view all the answers

What is the primary function of the occipital lobe?

Vision Signup and view all the answers

Broca's Aphasia is characterized by:

Inability to identify and string words together Signup and view all the answers

Which part of the neuron is primarily responsible for conducting electrical impulses away from the cell body?

Axon Signup and view all the answers

How does the brain exhibit cortical plasticity?

Through reorganization and adaptation Signup and view all the answers

What do sensory neurons primarily do?

Transduce external stimuli into neural signals Signup and view all the answers

Which structure helps speed up the transmission of electrical signals in neurons?

Node of Ranvier Signup and view all the answers

What is the correct sequence of events during action potential?

Resting state, depolarization, repolarization Signup and view all the answers

What role do glial cells play in the nervous system?

Providing support and protection for neurons Signup and view all the answers

What is the primary mechanism through which neurons communicate with each other?

Neurotransmitter release Signup and view all the answers

What does the Sparse Coding hypothesis suggest about the activation of neurons?

A small number of neurons are active for a complex stimulus Signup and view all the answers

What measurement technique is based on the hemodynamic response of the brain?

fMRI Signup and view all the answers

Which hypothesis states that a single neuron may code for a very specific object?

Grandmother Cell hypothesis Signup and view all the answers

What is the main purpose of Transcranial Magnetic Stimulation (TMS)?

To disrupt electrical activity in specific brain regions Signup and view all the answers

How do event-related potentials (ERPs) work in EEG measurements?

They detect specific changes in electrical charge relating to stimuli Signup and view all the answers

What does the Blood-oxygen-level dependent (BOLD) response measure in fMRI?

Oxygen release to active neurons Signup and view all the answers

What is the function of neural circuits?

To carry out specific functions when activated Signup and view all the answers

What is the primary function of the Central Nervous System (CNS)?

To process and integrate information Signup and view all the answers

Which of the following describes the function of the left hemisphere of the brain?

Language processing Signup and view all the answers

What is the significance of the corpus callosum?

It connects the left and right hemispheres of the brain Signup and view all the answers

What does the term 'contralateral processing' refer to?

Signals from one side are processed on the opposite side Signup and view all the answers

What is the function of gray matter in the cerebral cortex?

Houses neuron cell bodies Signup and view all the answers

What is the role of neuropsychology?

To investigate brain function and impairment due to brain pathology Signup and view all the answers

Which structure is known for being the outer layer of the brain?

Cerebral cortex Signup and view all the answers

What does the Encephalization Quotient (EQ) measure?

The actual brain size compared to predicted brain size based on body size Signup and view all the answers

Study Notes

Introduction to Neuroscience

Neuroscience explores brain structures and functions.
Macroscopic view includes recognizing parts of the brain.
Microscopic view focuses on neuronal information processing.

The Nervous System Overview

Comprises nerves and cells throughout the body.
Main goals: gather information, transmit to the central processor, execute behavior.

Nervous System Subsystems

Central Nervous System (CNS): Consists of the brain and spinal cord.
Peripheral Nervous System (PNS): Includes all other nerves not in the CNS.

The Cerebrum

The cerebral cortex is a folded, layered outer structure with subcortical regions.
Encephalization Quotient (EQ): Compares actual brain size to expected size based on body size.

Nervous System Terminology

Dorsal: Toward the top; Ventral: Toward the bottom.
Caudal/Posterior: Toward the back; Frontal/Anterior: Toward the front.
Contralateral: Signals processed on opposite sides; Ipsilateral: Signals processed on the same side.

Asymmetrical Processing

Most sensory information is processed contralaterally.
Exceptions include trunk and facial muscles, as well as visual processing fields.

Asymmetry in the Cortex

Left and right hemispheres possess different structures and functions.
Corpus callosum: Connective tissue linking the two hemispheres.

Anatomy of the Cerebral Cortex

Gray matter: Neuron cell bodies located externally.
White matter: Contains neuronal axons beneath gray matter.
Gyri: Ridges; Sulci: Grooves on the cerebral surface.

Anatomical Divisions of the Cortex

Hemispheres: Left and right.
Lobes: Frontal, temporal, parietal, occipital.

Functional Localization

Brain functions are localized; damage to specific areas results in unique impairments.
Neuropsychology examines these localizations and corresponding deficits.

Functional Localization by Hemispheres

Left hemisphere specializes in language processing.
Right hemisphere specializes in spatial processing.

Split-Brain Patients

Severing the corpus callosum prevents inter-hemispheric communication.
Results in discrepancies in perception and understanding between the two hemispheres.

Functional Localization by Lobes

Frontal lobe: Involved in higher-level thinking, movement, and decision-making.
Parietal lobe: Processes sensations and perceptions.
Temporal lobe: Responsible for hearing and memory functions.
Occipital lobe: Focused on visual processing.

Sensory & Motor Cortices

Motor Cortex: Engages in movement planning.
Somatosensory Cortex: Main area for touch sensation processing.

Evidence of Localization: Phineas Gage & Aphasia

Phineas Gage’s accident illustrated the link between specific brain regions and changes in personality.
Broca’s Aphasia: Affects speech production and word arrangement.
Wernicke’s Aphasia: Involves fluent yet nonsensical speech and impaired language comprehension.

Cortical Plasticity

The brain exhibits the ability to reorganize and adapt in response to experiences.

Limitations of Cognitive Neuroscience

Assumes distinct brain regions for different functions, yet the brain operates as an interconnected network.

Neurons

Neurons are the fundamental units of cognition.
Glial cells provide support and protection for neuronal cells.

Neuron Anatomy

Dendrites: Receive information; Cell Body (Soma): Maintains neuron function.
Axon: Conducts impulses away from the cell body; Axon Terminal: Transmits signals to other neurons.
Myelin Sheath: Fatty covering that enhances signal conduction; Node of Ranvier: Gaps speed up transmission.

Types of Neurons

Sensory Neurons: Afferent; bring input to the nervous system.
Association Neurons: Process and relay information.
Motor Neurons: Efferent; transmit output from the nervous system.

Conducting Impulses

Neurons maintain a negative charge at rest.
Action Potential: The electrical impulse triggered by a stimulus reaching the threshold.

Steps of Action Potential

Resting potential, threshold achievement, depolarization, repolarization, refractory period.

Neurons: Synaptic Connections

Synapse: Interaction point between neurons.
Neurotransmitters: Chemicals traveling across synapses for communication.
Reuptake: Process of reabsorbing excess neurotransmitters.

Effects of Neurotransmitters

Excitatory effect: Increases firing rate; Inhibitory effect: Decreases firing rate.
Agonists mimic neurotransmitters; Antagonists block their action.

Major Neurotransmitters

Acetylcholine, dopamine, glutamate, serotonin, norepinephrine, GABA.

Within vs. Between Neuron Communication

Action Potential: Electric signaling within a neuron.
Neurotransmitter Release: Chemical signaling between neurons.

Neural Circuits

A group of interconnected neurons functioning together in response to specific stimuli.
Neural Convergence: Multiple signals received by a single neuron.

Encoding Specificity

Specificity Encoding Hypothesis: Individual neurons may code for specific objects.
Distributed Encoding Hypothesis: Multiple neurons respond to a single stimulus, with activation patterns being significant.

Evidence for Encoding Specificity

Studies show selective neuron responses to specific images, though conclusive evidence remains elusive.

Hybrid Approach to Encoding Specificity

Sparse Coding Hypothesis: Small groups of neurons activated for complex stimuli; the combination is crucial.

Measuring Brain Activity

Cognitive neuroscience investigates neural processes, using techniques like EEG, fMRI, and TMS.

Electroencephalography (EEG)

Monitors brain electrical activity from the scalp.
Event Related Potential (ERP): Electrical changes in response to stimuli.

Functional Magnetic Resonance Imaging (fMRI)

Measures blood flow and metabolic activity in brain regions.
BOLD response: Indicates oxygen release to active neurons during tasks.

Transcranial Magnetic Stimulation (TMS)

Evaluates causal relationships between brain regions and behaviors.
Utilizes magnetic pulses to disrupt neuron activity in specific areas.

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Description

Test your knowledge on the firing mechanism of neurons, including the depolarization phase and the role of neurotransmitters in communication. This quiz also covers key concepts such as agonists vs. antagonists, the refractory period, reuptake, and the function of the occipital lobe.