Lectures Cognitive Neuroscience
Evolution and development of brain and cognition
Lecture 1 - Fr 19 april 2024
Open book exam (essay questions); you can bring physical materials (no internet and digital
devices).
The book chapters are relevant exam material (not everything will be discussed in lectures).
Cognition: the mental action or process of acquiring knowledge and understanding through
thought, experience and the senses.
Cognitive revolution
- In the first half of the 20th century behaviorism was the dominant theory in
psychology (not yet an interest in higher order processes).
- In the second half of the 20th century the cognitive revolution came:
-> Cognitive psychology: the study of higher mental processes like attention,
memory, problem solving, reasoning, and creativity.
-> Cognitive neuroscience: the study of neurobiological models related to mental
processes.
Evolution of the brain
- Charles Darwin: On the Origin of Species (1859) (natural selection).
First function of the brain: movement and sensation/perception of touch. -> if you are
completely sedentary, you don’t need a brain, e.g. plants.
The earliest “nervous system” dates back >500 million years: nerve nets with main
function: detect movement (sensory) and produce movement (motor).
Phylogenetic tree of vertebrates (have a spinal cord and a brain): an evolutionary
tree (=stamboom) of these species.
Human’s closest relatives are Chimpanzees and Bonobos; we share a common
ancestor about 7 million years ago. (short travel in time from past-now:)
-> The Australopithecus afarensis had many things in common with humans (the hips and
feet are pretty similar; this ape was much more bipedal than other apes).
-> The homo habilis and homo erectus looked more like current humans in appearance
and posture. Noticeable increase in brain size; start of tool use; changes in diet and lifestyle.
-> The homo Neanderthalensis and homo sapiens (first specimen 200-300 thousand
years ago; originate in Africa) are our closest ancestors (lived at the same time).
Neanderthals had large brains and almost similar cognition to that of homo sapiens: complex
spoken language; inner thought.
Brain size paradox: while the increase in brain size had to be crucial for our
survival, the correlation between brain size and cognition in modern humans is weak.
(-> 25% of all oxygen and nutrients goes to the brain).
-> Very recently human brain size has started to slightly decrease.
,Paleoneurobiology: (speculative!)
- Studying the brain using fossilized materials.
- Endocast: 3D representation of the skull cavity, which approximates the shape of the
brain (-> indication of (regional) brain size; asymmetries; location of major sulci).
Comparative neuroanatomy: comparing neuroanatomy of living evolutionary relatives:
- Human brains are often compared to those of Chimpanzee and Macaques.
- But comparative neuroscience can span much larger over more species, though the
implications will be more vague.
Brain size
Given the large difference between animals, general brain size is not a good indicator
of intelligence/cognition (the blue whale has the biggest brain size).
A logarithmic scale for relative brain size/weight to body weight is used. Deviations
from the predicted curve are called ‘residual brain size’ or ‘encephalization quotient’. The
higher/further on the linear prediction line, the higher the brain size relative to animal’s
bodies (=are relatively smart; snakes and chickens are quite low on the line, then birds,
higher humans and dolphins).
Brain size, but also other factors as number of neurons and connectivity, is indicative
of a specialized function of an animal.
Gyrification: increased cortical folding allows for an increase in brain size (mainly
cortical and cerebellar) without taking up more space; increases cortical surface tissue; is a
key feature in primates but also observed in other species.
Expansion of association cortex (those parts of cortex not related to receiving direct
input from senses (=primary cortices)): strong myelination is a key feature of primary
sensory/motor areas, whereas less myelination is observed in the association cortices.
The same language areas can be found in macaques as in humans. But they are
smaller and less lateralized. (in humans there is an increase of the arcuate fasciculus fibers
that connect Broca’s area with Wernicke’s area).
Approximate number systems are found in many animals (but special skill in
humans). Innate ratio processing is evident in many perceptual systems -also seen in
,infants. While number processing arithmetic ability seems to be a unique skill, it overlaps
strongly with other processes: spatial representation; mental rotation; WM.
While other apes can have excellent WM if there is a spatial component, they mostly
lack a phonological loop (so we humans have the advantages of using different WM
storages).
Primates have complex social structures. Group size moderately positively
correlates with brain size and complexity. Machiavellian intelligence hypothesis. Cortical
thickness is increased in macaques with a larger social network size in: -superior temporal
sulcus; -rostral prefrontal cortex.
Face perception is extremely active in humans (so much that we see faces in
everything: Pareidolia); they focus a lot on the eye movements of others.
There are several adaptations to modern life that cannot have been evolved, e.g.
reading, yet we do see a distinct brain area for letters and words.
Recapitulation theory (By Haeckel, 1870): development (ontogeny) follows
evolutionary history. “The development of advanced species passes through stages
represented by adult organisms of more primitive species -> FALSE theory.
Von Bear law (1828): “embryos of different members of the same group are more
alike than the adults, and the resemblances are greater the younger the embryos examined.”
Brain development
The neural tube contains neural precursor cells:
- They become neurons and glial cells
- Cells travel from the neural tube outwards, first forming deeper structures (thalamus,
hippocampus, etc) and later surface structures (cerebral cortex).
-> Almost all neurons we have as adults are present at birth.
Neurons and glia transition into different types after arrival and result in:
- Neurons with different transmitters
- Glia of different kinds (astrocytes, oligodendrocytes, etc.)
- Oligodendrocytes (crucial for myelination, which continues after birth and continues
until adolescence).
, The complexity of neurogenesis increased during the course of evolution: brain
increased in size and complexity (number of parts of which it consists).
Synaptogenesis and pruning is important for cognitive development:
- Synaptogenesis: the formation of new neural connections.
- Synaptic pruning: the loss of unused and superfluous synapses.
-> atypical synaptic pruning is related to some disorders, e.g. ASD and
schizophrenia.
Myelination happens in different regions at different times.
Methods in cognitive neuroscience
Lecture 2 - Fr 26 april 2024
Cognitive neuroscience methods:
- Neuroimaging (neuromonitoring): structure of the brain.
- Neurophysiological recordings (neuromonitoring): activity of the brain (location +
strength).
- Neuromodulation (perturbation): if you change the brain, how will its activity change.
All methods have advantages and disadvantages. Which method is best depends on the
research question and experimental design.
Indirect measures of brain activity:
From other parts of the body that tell you what the brain is doing. Examples are:
- Skin conductance response: autonomic nervous system; e.g. research on emotional
responses.
- Eye-tracking and pupillometry: e.g. research on attention, arousal or mental effort.
- Electromyography: e.g. motor functions.
Spatial (exact location) and temporal (now or delay in time) resolution of measures.
-> correlational methods: observe what is going on in the brain (neuroimaging). (e.g.,
single-unit recording, fMRI, EEG).
