Neuroscience Chapter 1 (good)

Neuroscience

The scientific study of how and why we experience aspects of human life such as sensation, movement, learning, memory, behavior, and disease through the nervous system.

Central question of neuroscience

How does the brain generate behavior?

Why study neuroscience?

Understanding the processes that make us human also helps us understand what happens when those processes go wrong in neurological and psychiatric diseases.

Structure-function relationship

A fundamental principle of neuroscience: functionally different components of the body tend to have different structures, and structural differences can provide clues about function.

Functional specialization

The idea that different regions or components of the nervous system are specialized for different functions.

Trepanation

An ancient practice involving drilling holes into the skull, apparently to alleviate some kind of problem.

Ancient Egyptian view of the mind

The Egyptians believed the mind was associated with the heart rather than the brain.

Hippocrates

An ancient physician who argued that the brain is involved in sensation and is the seat of intelligence, challenging the idea that the heart was the center of the mind.

Galen

A physician who performed careful brain dissections and anatomical drawings and recognized roles for the brain in sensation and memory.

Galen's structure-function reasoning

Galen used differences in brain structure, such as differences between the cerebrum and cerebellum, to propose that different brain regions had different functions.

Galen's ventricular theory

Galen proposed that movement occurred through the movement of fluids from the brain's ventricles into the nerves and muscles.

Why was Galen's ventricular theory eventually rejected?

Experiments involving electrical stimulation of nerves and muscles demonstrated that electrical activity, rather than fluid movement, could produce muscle contractions.

Descartes

Proposed dualism, spinal reflexes and neural pathways, and the idea that the pineal gland was a junction between the nonmaterial mind and the material body.

Dualism

The philosophical idea that humans have both a nonmaterial mind or soul and a material body.

Mind-brain problem

The question of how the mind relates to the physical brain; Descartes treated the mind as separate from the material brain.

Central nervous system (CNS)

The brain and spinal cord.

Peripheral nervous system (PNS)

The networks of nerves throughout the body outside the brain and spinal cord.

White matter

Brain tissue containing many nerve fibers; its continuity with nerves helped suggest a role in signal transmission.

Gyri

The bumps on the surface of the cerebrum.

Sulci

The grooves on the surface of the cerebrum.

Cerebral localization

The idea that different parts of the brain are specialized for different functions.

Why were gyri and sulci historically important?

Their relatively consistent locations across individuals suggested that structural organization of the brain might correspond to meaningful functional organization.

Phrenology

The incorrect attempt to infer human mental traits from the size and shape of bumps on the skull.

Why is phrenology considered invalid?

Skull shape and size do not accurately reveal the structure or functional organization of the underlying brain.

Why is phrenology still historically relevant?

It was based on the incorrect reasoning that brain function is localized, but the brain really is functionally organized; later experiments provided valid evidence for localization.

Galvani

An investigator whose experiments demonstrated that electrical stimulation could cause muscles to contract, supporting the idea of animal electricity.

du Bois-Reymond

An investigator who contributed evidence that electrical activity is involved in nerve signaling.

Animal electricity

The idea that electrical processes are responsible for signaling in nervous and muscular tissue.

Bell and Magendie

Scientists who provided evidence that sensory and motor information travel through different nerve roots.

Dorsal root

Associated with sensory input; cutting it can block sensation.

Ventral root

Associated with motor output; cutting it can cause paralysis.

Bell-Magendie principle

The principle that sensory information enters through dorsal roots while motor commands leave through ventral roots.

Flourens

Used ablation experiments to study localization of function and concluded that the cerebellum is important for movement while the cerebrum contributes to sensation and perception.

Fritsch

Used electrical stimulation of the cortex to demonstrate that stimulating specific cortical areas could produce movement in specific muscles.

Ferrier

Used lesioning experiments showing that damaging a cortical area responsible for evoking a muscle movement could cause paralysis of that movement.

Ablation

The experimental removal or destruction of a brain region to determine its contribution to behavior or function.

Electrical stimulation as a neuroscience method

Stimulating a specific brain region and observing the resulting behavior or movement can provide evidence about that region's function.

Broca's area

A region associated with speech production; damage can produce an inability to speak despite preserved ability to understand language.

Localization of speech function

Brain damage to specific regions can produce selective deficits in speech, providing evidence that particular functions depend on particular brain regions.

Henry Molaison (H.M.)

A famous patient whose temporal lobe surgery for severe seizures caused an inability to form new long-term memories while leaving older memories and the ability to learn new motor skills relatively intact.

What did H.M. teach neuroscientists?

Memory is not a single uniform process and particular brain regions are important for forming new long-term memories.

H.M. and motor learning

H.M. retained the ability to acquire new motor skills even though he could not form new long-term memories, showing that different forms of memory depend on different neural systems.

Phineas Gage

A railroad worker who survived severe damage to the frontal part of his brain and subsequently showed profound personality changes, providing historical evidence linking brain regions to aspects of behavior and personality.

What did Phineas Gage demonstrate?

Brain injury can produce selective changes in personality and behavior, supporting the relationship between particular brain regions and particular functions.

Experimental ablation

One of the major historical methods for studying localization of brain function; researchers removed or damaged regions and observed behavioral consequences.

Why are case studies such as H.M. and Phineas Gage useful?

They provide evidence that damage to particular brain regions can selectively alter specific behaviors or cognitive abilities.

Darwin's contribution to neuroscience

Darwin's theory of evolution by common ancestry provided a framework for understanding conserved physical and behavioral traits across species.

Why can animal research inform human neuroscience?

Many neural structures, mechanisms, and behaviors are conserved across species, allowing simpler organisms to reveal general principles of nervous system function.

Conserved neural mechanisms

Neural structures or mechanisms shared across species because of evolutionary conservation.

Why are rodents commonly used as neuroscience models?

They have well-studied genetics, relatively simple nervous systems, rapid reproduction, and many conserved neural structures and mechanisms shared with humans.

Similarities between rodent and human brains

They share major structures such as cerebral hemispheres, cerebellum, ventricles, brainstem, spinal cord, and general symmetry.

Conserved organization of vertebrate cortex

The cortex commonly contains layers with different cell types and similar basic organization across vertebrate species.

Highly conserved cortical feature

Organization into layers containing different cell types.

Cortical expansion across evolution

The amount and relative size of cortex can evolve substantially even when its basic organizational structure remains conserved.

Why can different species have different specialized brain regions?

Evolution modifies conserved neural structures according to species-specific sensory, motor, and behavioral demands.

Primate visual specialization

Primates have highly developed visual systems and specialized visual cortical structures related to color vision.

Mouse somatosensory specialization

Mice use whiskers for navigation and therefore have specialized organization for whisker information in somatosensory cortex.

Behavioral neuroscience

The study of how neural systems and mechanisms relate to behavior.

Systems neuroscience

The study of how neural circuits integrate information to generate behavior and other functions.

Cellular neuroscience

The study of cellular electrical properties and neural connectivity, often at the level of individual cells or partially intact circuits.

Molecular neuroscience

The study of genes, proteins, ion channels, and other molecular components involved in nervous system function.

Cognitive neuroscience

The study of how and where cognitive processes are generated, including processes such as consciousness.

Why is neuroscience multidisciplinary?

The nervous system must be studied at multiple levels, from genes and proteins to individual neurons, circuits, behavior, and cognition.

Why is the brain difficult to understand?

Neurons are small and densely packed, each neuron can have thousands of connections, intrinsic properties change dynamically, and physical connections can change throughout life.

MICrONS

The Machine Intelligence from Cortical Networks program, which seeks to map neural circuits and their function to better understand computational principles of the brain.

Neuroscience and disease

Understanding normal neural mechanisms helps explain neurological and psychiatric disorders and can guide development of treatments.

Why can studying simple systems help explain the human brain?

Basic neural principles and mechanisms are often conserved, so studying simpler organisms can reveal general principles that apply to more complex nervous systems.

Neuroscience ethics

Neuroscience research must consider ethical issues associated with human and animal research and is heavily regulated.

Noninvasive neuroscience methods

Methods that study the brain without physically damaging or removing brain tissue.