CH3: Neuroscience

Question 1

Darwinian Evolution

Answer 1

Darwinian Evolution of natural selection is the unifying theory of biological sciences. There are 4 conditions to this theory:
Reproduction, Heritability of traits, Variation of traits in a population via mutation and assortative mating, and Differential survival “selection”.

Question 2

Evolution Basics

Answer 2

There are 3 basics to evolution. Selection pressures are aspects of an environment in which an organism must adapt. Fitness refers to the degree an organism can adapt to their environment. Spectation occurs whe na group splits and the populations adapt in distinct ways until individuals are no longer able to reproduce with each other.

Question 3

Human Evolution

Answer 3

The last common ancestor between humans and ape relatives lived about 5 million years ago. Many hominid species co-existed with our ancestors until “recently”. Anatomically modern humans loved at least 300k years ago. Humans do not have the largest brain, but we have the highest encephalization factor (EF) which is the measure ratio between brain weight to body weight.

Question 4

The Idea of the Brain

Answer 4

Thousands of years ago, trepanation, which is the practice of surgically cutting holes into the skull was a common practice. It was widespread in several continents. It’s purpose is still being questioned and likely was for treating head injuries, seizures, etc.

Question 5

The Neuron Doctrine

Answer 5

Ramon Santiago y Cajal showed that the nervous system was made of individual cells called neurons. These neurons communicate with each other through synapses. Neurons have 3 parts: Dendrites, Soma/cell body, and Axons.

Question 6

Neurophysiology: Membrane Potentials

Answer 6

Postsynaptic potentials (PSPs) are induced changes to the resting potential; excitatory or inhibitory. Excitatory signals depolarize the postsynaptic neuron, making cells more positively charged. Inhibitory signals hyperpolaroize the postsynaptic neuron, making cells more megatively charged. PSPs from many synapses are found in the soma. An Axon hillock in the soma will fire an action potential if it reaches about -40mV.

Question 7

Neurophysiology: The Synapse

Answer 7

The points of communication between neurons. There are 3 points:
Axon terminals release chemical neurotransmitters in response to action potentials.
Synaptic cleft is the space between neurons.
Postsynaptic neurons are the neurotransmitters bind to receptors and generate post-synaptic potentials, electrical signals in the next neuron.

Question 8

Neurophysiology: Neurotransmitters

Answer 8

There are hundred of distinct neurotransmitters including 5 classical small molecules:
Gultamate: primary excitatory
GABA: primary inhibitory
Acetylcholine: neuromuscular junctions and brain modulator
Dopamine: reward prediction
Norepinephrine: arousal, memory
Serotonin: mood, memory

Question 9

The Nervous System and Mind

Answer 9

Every experience that we have is generated by processes of our nervous systems.
Perception (the 5 senses), Affect (emotion), Cognition (attention, memory), and Behaviour (movement, self-regulation).

Question 10

Neuroanatomy

Answer 10

The nervous system is organized with 2 major components: Peripheral nervous system, which features the autonomic nervous system and the somatic nervous system, and the central nervous system, which features the spinal cord and brain.

Question 11

Autonomic Nervous System

Answer 11

The sensory and motor functions the viscera. Several of them involve relay ganglia. Sympathetic division is generally activating, towards fight-flight-freeze. Parasympathetic division is generall calming, towards rest-and-digest.

Question 12

Somatic Nervous System

Answer 12

Sensory signal reach the brain to help with movement programs. Afferent sensory nerves enter the dorsal spinal cord. Mainly the somatosensory. Effernt motor nerves exit form the ventral spinal cord. Mainly the motor system. Reflexes are at the level of the spinal cord.

Question 13

Spinal Cord

Answer 13

The foundation unit of all behaviour is the reflex. A reflect can be made of 2 neurons: a sensory neuron that transduces information from the receptor cells, and a motor neuron that responds to the sensory signals. Sensory information is also passed along to the brain for more complex decision-making.

Question 14

Hindbrain and Midbrain

Answer 14

There are 4 parts to the hindbrain and midbrain:
Medulla, Pons, Cerebellum, and Midbrain. All but Cerebellum include the cranial nerve and other nuclei.

Question 15

Forebrain

Answer 15

There are 2 systems in the forebrain with their own subsystems.
Basal Ganglia (movement). Substantia nigra: dopamine
Striatum: motivation and vigour
Limbic System (memory/emotion).
Septal nuclei: pleasure
Amygdala: emotional valence such as fear
Hippocampus: homeostasis
Thalamus: general forebrain integrator

Question 16

Forebrain: Neocortex

Answer 16

Cortex is the outer layers of the brain’s neurons which procceses all conscious experiences. There are 4-5 lobes:
Frontal: movement, higher cognition
Temporal: Hearing, object recognition
Parietal: touch, spatial processes
Occipital: vision
(Insula): visceral sensation

Question 17

Brain Function

Answer 17

Regions of the cortex are specialized for different functions: sensation/perception, emotion, cognition, or movement. There are 2 functions to brain function. Precentral gyrus initiates voluntary movements, primary motor cortex. Postcentral gyrus processes touch from skin, primary somatosensory cortex. Both are organized as body maps based on physiological activity.

Question 18

Brain Function: Language

Answer 18

Human language depends on a network of cortical structures:
Broca’s area is involved in syntax
Wernicke’s area is involved in verbal comprehension
Arcuate fasciculus is the axons that connects auditory and sensorimotor regions with the other areas.

Question 19

Tools for Measuring the Brain

Answer 19

Many techniques are used to examine and measure the brain.
Examining autopsy tissue, Recording electrical activity through electroencephalography, recording magnetic activity through magnetoencephalography, and brain imaging through computerized tomography and others.