In part 3 of our journey through the visual system, we discuss the structure and function of the Primary Visual Cortex, including an analysis of occular dominance columns, orientation columns, and the six cortical layers. I also cover higher cortical regions involved in visual processing, including the V2, V3, V4, and IT areas, and how these regions are divided into distinct 'what' and 'where' processing pathways.
Resuming from where we left off last time, we continue our journey through the visual system by explaining the structure and function of the bipolar and ganglion cells in the retina, including their somewhat complex receptive fields. I then discuss the optic nerve and cross over of information from different visual hemifields at the optic chiasm. We end this part of our journey with a look at the lateral geniculate nucleus, and how it is structurally organised to process different types of visual information in different locations.
We commence our grant journey to understand the visual system by examining the eye, its anatomical structure and physiological properties. I discuss image formation in the eye, including an explanation of the role of the lens, iris, and cornea. I also explain the phototransduction, the fascinating molecular process by which photons falling on the retina are converted into neural signals that the brain can interpret. Recommended prelistening: Episode 18 - Biochemistry Basics, Episode 25 - Tissues, Organs and Systems, Episode 32 - Light and Optics, Episode 38 - Neurons and Synapses.
A discussion of the cell cycle and cell division, beginning with an overview of chromosomes and chromosome structure, and then proceeding through a detailed discussion of the G1, S, and G2 stages of interphase, and the prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis phases of M-phase. I conclude the episode with a discussion of cell-cycle regulation, including the role of cyclin-dependent kinases, cell checkpoints, and growth factors. Recommended prerequisites are Episode 10: The Cell, Episode 18: Biochemistry Basics, and Episodes 34 and 35: DNA Structure and Function.
An overview of the basics of electric charges, electric fields, and electric potential energy. I also discuss how objects become charged, how charged particles interact via Coulomb’s Law, how electroscopes work, and how batteries generate voltage. Recommended prerequisites are Episode 9: Matter and Molecules, and Episode 17: Energy, Work, and Momentum.
A discussion of the properties and behaviour of gases, focusing on the kinetic theory of gases and the ideal gas law. I also discuss the thermodynamic behaviours of gases, gas partial pressures, and PV diagrams. Recommended prerequisites are Episode 9: Matter and Molecules and Episode 13: Newtonian Mechanics.
A discussion of the behaviour of fluids, including an overview of the concepts of fluid pressure and Pascal’s Principle. I also discuss Archimedes’ principle of buoyancy and its application to why objects float, and Bernoulli’s Principle of the relationship between fluid speed and pressure, and how this can be applied (and misapplied) to explaining how aeroplanes fly. Recommended prerequisites: Episode 13 Newtonian Mechanics, Episode 27 Intermolecular Bonds and Phase Transitions.
A science-based discussion of the issue of gun control in the United States. After reviewing some basic statistics about crime and gun ownership, I examine the empirical evidence concerning the relationship between gun ownership and violent crime, highlighting the many difficulties associated with such studies and the limitations of this literature. I then discuss some more specific aspects of the gun control debate, including the question of who commits most violent crimes, how deadly guns are compared to other weapons, and how criminals acquire guns. I conclude with a discussion of the evidence for and against various types of gun control measures, and some thoughts on contemporary US gun culture and its impact on gun policy.
An overview of the state as understood in political science, including a discussion of the meaning of terms like ‘state’, ‘country’ and ‘nation’, and a summary of some of the different types of states, including unitary, federal, and confederal. I also discuss some of the core principles of government in modern states, including sovereignty, the rule of law, separation of powers, and separation of church and state.
A discussion of the neuron, the fundamental cell of the brain and the nervous system, including an overview of its morphology and physiology. I also discuss the generation and propagation of action potentials, including the role of graded potentials, voltage-dependant ion channels, and myelination. The episode concludes with an overview of synapses and the important role of neurotransmitters.
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