Neuropsychology
College 1: evolution and function if the nervous system
Evolution and historical perspectives on mind and brain
Why the brain is so important
- The brains primary function is to produce behavior. To do so it must;
o Receive information about the world (trough senses)
o Integrate information to create a sensory reality
▪ Feels real to us, but is different for every species, so there is no real
sensory experience
o Make a constant stream of predictions about what to expect
▪ Only if you can make predictions, you can adapt your behavior
o Produce commands to control the movement of muscles
▪ The behavior we observe is a product of this command and muscles
- The makeup of the nervous system altogether allows the brain to do so
What is behavior
- Relatively fixed behavior → Dependent on heredity (you can easily do)
- Relatively flexible behavior → Dependent on learning
- Complexity of behavior varies considerably in different species depending on
complexity of the nervous system (and the brain)
o The more complex the system, more complex brain, more complex behavior
Philosophy of brain and behavior: Aristotle and mentalism
- Mentalism (start): an explanation of behavior as a function of the nonmaterial mind
- Ancient Greece/ Aristotle: psyche or soul: synonym for mind, an entity once
proposed to be the source of human behavior that lives after death
o Was not observable
After that: Descartes and dualism
- Solve problem that how can our body be influenced by something that isn’t there
- Both a nonmaterial mind and the material body contribute to behavior
- Mind directs rational behavior
- Body and brain direct all other behavior via mechanical and psychical principles
- Mind is connected to the body through the pineal gland of the brain
- Simple behaviors are controlled by the body
- → but difficult to prove and everything
o mind-body problem: difficult/ impossible to explain a nonmaterial mind in
command of a material body
→ solution be Darwin and materialism (still believe in now)
- materialism: behavior can be explained as a function of the nervous system without
considering the mind as a separate substance
o Related to evolutionary theory of Darwin
o Does not say there is nothing like thoughts or emotions
- Darwins concept of natural selection:
o Differential success in reproduction of different characteristics/ behavior
(phenotypes) results from the interaction of organism with their environment
o → changes to pass on genes are higher if you are better able to cope with
environments → that is how species develop
, o Traits/ behavior that increase reproductive success and changes of survival
will be passed on to offspring → competition is a key concept
Evolution of animals having nervous systems → from easy to complex
- Nerve net → segmented nerve trunk → ganglia → brain
- Also with humans it is likely we started as a very basic nervous system
- But everyone adapted in a different way → that made it that our brain could better
develop and become more and more complex
- The human brain now has the largest size relative to body weight, and the higher this
ratio, the more complex behavior you can show → Humans highest ratio
Neuroplasticity → the brain is plastic
- Neural tissue has the capacity to adapt to the world by changing how its functions
are organized
o Its changing and developing as a function of how you behave and interact
with the environment → your behavior also changes your brain
- Because the brain can adapt to the world, different species could develop
- It is seen both in developing brain and in adaptions of brain structure following injury
o Children in more stimulating environments have different brains than children
poor environments
Epigenetics
- How the brain can adapt is related to epigenetics
o Epigenetics: how the environment can influence brain function because it can
turn on and off curtain genes and that influences the make up of brain
- Study of differences in gene expression related to environment and experience
- Epigenetic factors don’t change your genes, but do influence how your genes operate
- Epigenetic changes can persist throughout a lifetime, and the cumulative effects can
make dramatic differences in how your genes work and how likely a species is to pass
on its genes → evolution
Phenotypic plasticity:
- An individual’s genotype (genetic makeup) interacts with the environment to elicit a
specific phenotype from a large repertoire of possibilities
o Example: same DNA but different food so metabolism changed
Studying brain and behavior in modern humans
- The brain, especially the cortex, is highly flexible
- That means humans can live very different lifestyles in very different environments,
with equal skill and success. That also means that individuals differences in brain
organization are huge! → there is no average brain
o Can only say things about populations, it is always about general effects
Anatomical and functional divisions of the nervous system
, - The bacteria in the guts have a big impact on our brain → so what you eat can affect
your mood
The brain
Overview of the structure of the brain:
- Forebrain: major structure, consisting of two almost identical hemispheres.
Prominent in mammals and birds, responsible for most higher order conscious
behavior → The bigger, the more complex behavior
- Cerebellum: little brain. Involved in the coordination of motor and cognitive
processes → has actually as many neurons as the rest of the brain
- Brainstem: central structures of the brain including hindbrain, midbrain, thalamus
and hypothalamus. Source of behavior in simple animals, responsible for most of our
unconscious behaviors
- Spinal cord: consist of nerves that carry incoming and outgoing messages between
brain and the rest of the body including reflexes
-
- More complex animals have more complex brains. The forebrain and cortex are the
highest in the hierarchy and explain the most complex behavior
Forebrain
- Cerebral/ Neo cortex → is a thin sheet composed of 6 layers of different types of
nerve cells folded many times to fit inside the skull responsible for regulating various
mental activities (higher order activities)
o Gyri are the bumps, sulci are the grooves
- Allocortex cortex: evolutionary older part of cortex consisting of 3 or 4 layers of
nerve cells present in structures of the limbic system (cingulate cortex, hippocampus,
amygdala), as well as structures related to olfactory system
o Cingulate cortex: controlling motivational states, attention and self-
monitoring (oops response comes from here)
Orientation
- “anatomical orientation” illustrates direction of a cut, or section through the brain
(part a) from the perspective of a viewer (part b)
o Coronal (frontal -), horizontal (dorsal -), sagittal (medial view)
, - “brain-body orientation” illustrates brain-structure location from the frame of
reference of the face
o Dorsal (top), ventral (bottom brain), rostral (anterior, front), lateral (side),
medial (midden)
Cell structure of neurons: important structural categories
- Gray matter (the cortex):
o The actual cell bodies (about 80 billion neurons) and
their dendrites
o Cell bodies/ somas are aligned in the cortex
- White matter:
o Fat-sheathed neuronal axons, plus glial cells (about 100 billion) for structural
support
- Corpus callosum
o Fiber system consisting white matter tracts connecting the two hemispheres
o The corpus callosum is largest white matter structure, consisting of 200- 250
million contralateral axonal projections
- Axons running together form nerve outside CNS, tract within CNS
Lobes of cerebral cortex
- Frontal: speech, initiates muscle movement, planning, decision making and EF
- Parietal: cognitive and sensory integration for touch and body position, attention
- Temporal: auditory, taste, memory, sensory integration → recognizes faces
- Occipital: visual
Forebrain: basal ganglia
- Controls voluntary movement: control and coordination of movement patterns
rather than deciding to move or activating the muscles to move.
o Is already here in less complex animals, less complex function
o Many regions work together from different layers for movement
- Works together with thalamus, substantia nigra and subthalamic nucleus
- Related disorders: Parkinson’s and Tourette’s
Forebrain: limbic system
- Group of structures between cortex and brain stem
- Principal structures: amygdala, hippocampus and cingulate cortex
- Allocortex → again evolutionary a bit older
- Regulates emotions and MEMORY (to inform for dangers fe
animals)
- Hippocampus: representing Episodic memories
o Some become semantic memories, not associated with
any particular event
- Amygdala: emotional associations (emotional memories) are formed here
