Introduction to Neuroscience

Introduction to Neuroscience

• Luigi Galvani discovered that a frog's leg twitched when stimulated with electricity, even when the nerve and muscle were removed (1700)
• Gustav Fritsch and Eduard Hitzig demonstrated that electric stimulation of the brain could cause movement in dogs (1870)
• Hermann von Helmholtz showed that nerves do not behave like wires conducting electricity and conducted studies on vision and hearing, proposing a mechanistic mind

Localization Issue

• The idea that specific areas of the brain carry out specific functions was first proposed by Fritsch and Hitzig's studies with dogs
• Phineas Gage's case (1848) showed that damage to the frontal lobe did not impair intelligence, memory, speech, or movement, but led to changes in behavior and social conventions
• Paul Broca's autopsy (1861) found that a man who lost the ability to speak after a stroke had damage to the left side of the brain, now known as Broca's area

Nature and Nurture

• The debate questions the relative importance of heredity and environmental influences in shaping behavior
• Genetic information is stored in DNA, a double-stranded chain of chemical molecules twisted around itself (double helix)

Genetic Information

• James Watson and Francis Crick published the proposed structure for DNA (1953)
• DNA consists of four nucleotides: adenine, thymine, guanine, and cytosine
• Alleles are different versions of a gene, and can be dominant or recessive

Heredity

• Darwin's theory of natural selection states that more adaptive genes are more likely to survive and transmit their genes to more offspring
• Genes have varying degrees of effect, and heritability measures the percentage of variation in a characteristic attributed to genetic factors

Origin of Species

• The connection between humans and non-human animals was established, and understanding animal behavior helps understand human behavior

Number of Chromosomes

• Each species has a fixed number of chromosomes in each cell, unique to that species
• Examples include humans (46), hermit crab (254), goldfish (100), pigeon (80), dog (78), elephant (56), and fruit fly (8)

Stages of Early Development

• Gametogenesis produces sperm and egg cells
• Fertilization results in a zygote
• Cleavage leads to a blastula or blastocyst
• Gastrulation forms a gastrula with three germ layers
• Organogenesis results in an embryo
• Morphogenesis produces a fetus

Basic Cell Structure

• Cell membrane: a bilayer lipid membrane with embedded proteins
• Cytoplasm: water and ions
• Nucleus: membrane-bound, containing chromosomes with DNA
• Organelles: smaller functional structures within the nucleus or cytoplasm

The Genetic Code

• A gene is a biological unit that directs cellular processes and transmits inherited characteristics
• Genes are found on chromosomes and serve as units of inheritance and regulate cellular physiology
• Each pair of chromosomes is unique, with genes for different functions located on specific chromosomes

Chromosomal Karyotype

• A standard chromosomal karyotype shows the 23 pairs of human chromosomes, numbered 1-22 and X/Y

Mind-Brain Problem

• The mind is a concept composed of brain activities, such as thinking, sensing, planning, and feeling
• Monism proposes that the mind and body consist of one substance, while dualism proposes that they are separate entities
• Models in science, such as Descartes' Hydraulic Model, propose mechanisms for how things work

Behavioral Neuroscience

• Behavioral neuroscience is the branch of psychology that studies the relationship between behavior and the body-brain
• Also known as physiological psychology, biopsychology, or psychobiology
• Key applications include understanding behavior and its biological mechanisms

A brief overview of the history of neuroscience, covering key figures and their contributions, including Galvani, Fritsch, Hitzig, and Helmholtz. Explore the early studies on the brain and nervous system.