Ch 3 Neuroscience Flashcards
1
Q
Darwinian evolution
A
Is the unifying theory of the biological sciences.
Evolution requires 4 conditions
1.reproduction
2.heritability of traits
3.variation of traits in a population
4.different survival and selection
2
Q
Evolution basics
A
-selection pressure: are aspects of the environment to which an organism must “adapt”
-fitness:refers to the relative degree to which an organism can adapt to their environment.
-“Survival of the fittest”:refers to the heritable traits passed on to the next generation of organisms.
-Speciation: occurs when a group splits and the population adapt in distinct ways until individuals are no longer able to reproduce.
3
Q
Human Evolution
A
- The last common ancestor
between humans and our nearest
living ape relatives (chimpanzees
and bonobos) lived ~5 MYA - Many hominid species co-existed
with our ancestors until “recently” - Anatomically modern humans
(i.e., same skull and brain size)
lived at least 300,000 years ago - All humans lived in (mostly) east
Africa until ~60,000 years ago - Humans do not have the largest
mammalian brain - Blue and sperm whales, elephants,
etc. have much larger brains - So, what makes us “different”?
- The encephalization factor (EF)
is a measure of the ratio of brain
weight to body weight - Measures some relative amount of
brain dedicated to higher cognition - Humans have the highest EF
4
Q
The Idea of the Brain
A
- Ancient Origins:
- Trepanation, surgical holes cut
into the skulls of living individuals,
was a relatively common practice - Dates back many thousands of years
- Widespread across several continents
and most frequently seen in Peru - Purposes are still contested and likely
varied from treating head injuries,
seizures, and relieving pressure, to
perhaps treating symptoms of
psychoses like schizophrenia
5
Q
The Neuron Doctrine
A
- In 1888 CE, a major debate was
settled over the structure of the
nervous system - A continuous net or reticulum?
- A network made of individual cells?
- Ramon Santiago y Cajal showed
that the nervous system was made
of individual cells called neurons - Neurons communicate with each
other across gaps called synapses - Neurons have three parts:
- Dendrites (input)
- Soma/cell body (integration)
- Axons (output)
6
Q
Neurophysiology: Membrane Potentials
A
- Every cell is encapsulated by a
membrane(phospholipid bilayer) - Membrane potentials underly the
neuron’s ability to communicate - Resting membrane potential
- Baseline difference in the number of
charged ions inside and outside cells - Approximately -65mV
- Generated by electrostatic pressure
and ion concentration gradients - Maintained/restored by Na+-K+ pumps
- Postsynaptic potentials (PSPs) are
induced changes to the resting
potential; excitatory or inhibitory - Excitatory signals depolarize the
postsynaptic neuron - Makescellmore positively charged
- Inhibitory signals hyperpolarize the
postsynaptic neuron - Makescellmore negatively charged
- PSPs from many synapses are
summed in the soma (cell body) - When the axon hillock in the soma
reaches ~-40mV, an action potential
fires and is conducted down the axon
7
Q
Neurophysiology: The Synapse
A
- The points of communication
between neurons are synapses - Axon terminals
- Release chemical neurotransmitters
in response to action potentials - Synaptic cleft
- Space between neurons
- Postsynaptic neuron
- Neurotransmitters bind to receptors
and generate post-synaptic potentials - Electrical signals in the next neuron
8
Q
Neurophysiology: Neurotransmitters
A
- There are hundreds of distinct
neurotransmitters, including six
“classical” small molecules: - Glutamate
: primary excitatory - GABA
: primary inhibitory - Acetylcholine
: neuromuscular
junctions and brain modulator - Movement, memory, attention
- Dopamine
: reward prediction - A “seeking” system, motivation
- Norepinephrine
: arousal, memory - Alerting, vigilance, etc.
- Serotonin
: mood, memory - Emotion, desire, etc.
9
Q
The Nervous System and Mind
A
- Everyexperience that we have is
generated by processes of our
nervous systems - Perception
- vision, hearing, touch, smell, taste, etc.
- Affect (emotion)
- seeking, fear, rage, lust, care, grief, joy,
guilt, shame, jealousy, pride, empathy,
embarrassment, compassion, etc. - Cognition
- attention, memory, language, thought,
decision-making, metacognition, etc. - Behavior (movement, self-regulation)
10
Q
Neuroanatomy
A
- The nervous system is organized
hierarchically, with two major
components by convention: - Peripheral nervous system (PNS)
- Autonomic nervous system (ANS)
- Enteric (gut) nervous system (ENS)
- Somatic nervous system (SNS)
- Central nervous system (CNS)
- Spinal cord
- Brain
11
Q
Autonomic Nervous System
A
- Sensory and motor functions of
the viscera (internal organs,
glands, etc.) - Several of them involve relay
ganglia - Sympathetic division
- Generally, “activating”
- Towards “fight-flight-freeze”
- Parasympathetic division
- Generally, “calming”
- Towards “rest-and-digest”
12
Q
Somatic Nervous System
A
- Afferent sensory nerves
- Enters the dorsal spinal cord
- Somatosensory (touch)
- Efferent motor nerves
- Exits from the ventral spinal cord
- Motor system (movement)
- Reflexes at level of spinal cord
- Sensory signals reach the brain
and help to update movement
programs
13
Q
Spinal Cord
A
- The foundational unit of all
behaviour is the reflex - A simple reflex can be made of
only two neurons:
1. A sensory neuron that transduces
information from receptor cells
2. A motor neuron that responds to
those sensory signals - Sensory information is also
passed along to the brain for
more complex decision-making
14
Q
Hindbrain and Midbrain
A
- Medulla
- “Life support systems” (ANS)
- Reticular activating system
- Cranial nerve and other nuclei
- Pons
- Cranial nerve and other nuclei
- Cerebellum
- ~Half of the neurons in the brain
- Motor programs (skilled movement)
- Midbrain
- Cranial nerve and other nuclei
- Sensory & motor “relays”, other nuclei
15
Q
Forebrain (except the neocortex)
A
- Basal Ganglia (movement):
- Substantia nigra: dopamine to…
- Striatum: motivation and vigour
- Made of the caudate and putamen
- Limbic System (memory/emotion)
- Septal nuclei: pleasure
- Amygdala: emotional valence (fear)
- Hippocampus: episodic memory
consolidation - Hypothalamus: homeostasis
- Thalamus: general forebrain integrator
