Psychology 1A Module from the University of Edinburgh. Very comprehensive notes made after watching lectures twice using lecture recordings, summarising both PowerPoint notes and important remarks made by lecturers, word for word. For reference, I got an A1 in this course using these notes.
Cognitive Neuroscience (Lectures 4-9)
Lecture 4: The mind as a biological system (Mon 23 Sept)
Cognitive Neuroscience: The scientific study of biological substrates underlying cognition,
with a specific focus on neural substrates of mental processes. Addresses how
psychological/cognitive functions are produced by neural circuits in the brain and how the
brain influences/ controls memory, language, personality…
We look at how these functions are produced by the brain. To study this, we can look at
patients with brain damage, use neuroimaging techniques, study and measure animals’
brain activity… Basically: How the brain creates the mind.
-Why do we have blind spots?
Light comes in through the pupil and the lens of the eye focuses the image you’re looking at
in the back of the eye. Light waves need to be converted into a language that the brain can
understand. The back of the eye has photoreceptors that transform light into an
electrochemical signal, which is sent to the brain. The fovea is the area where you have the
greatest number of this photoreceptors; that is where your vision is more acute. The optic
nerve is where all the axons of the photoreceptors leave the eye. In this area, we don’t have
any photoreceptor cells, which causes the light in that particular area to not be processed,
creating a blind spot. The brain will fill in that blind spot with information from the
environment.
-We have a right and a left primary somatosensory cortex in our brains. That’s the bain area
that receives information about sensation (touch, pain…). The left side of the body sends
info to the right somatosensory cortex and the right side of the body to the left. Areas of the
body that are close to each other are not necessarily mapped on the brain near each other.
Certain parts of the body have much larger areas of cortex (eyes, fingers, lips, nose have a
much bigger area than legs or hips). The size of the area associated with a body part is not
necessarily in relation to the real size of the body part. The more cortex that is allocated to a
body part, the more sensitive that body part will be.
Mental functions are the product of activity in the nervous system. The nervous system:
-Receives sensory information from the environment
-Integrates and processes information
-Regulates internal functions
-Produces motor actions
Levels of observation of living beings:
Genes, cells, tissues, organs, systems, body.
Structure of the living cell:
-Membrane: forms the structure of the cell. Is semipermeable (can let certain things through,
protecting the cell).
-Nucleus and nucleolus (contains the DNA)
-Channels on the membrane: made out of proteins and allow substances to come back and
forth
-Proteins with specialized functions
-Mitochondria: converts nutrients into ATP for chemical energy needed for vital functions of
, Cognitive Neuroscience (Lectures 4-9)
the cell.
Cells of the nervous system:
+neurons
+glial cells (they are supporting cells for the neurons, we have 10 times as many glial cells
as neurones)
-Different types of glia cells:
Schwann cells (insulate the cell to ensure the signal happens quickly and isn’t lost)
Oligodendrocytes (form myelin as insulation for the cells)
Myth: no new neurons are created in the adult brain.
Certain areas of the brain (olfactory bulb, dentate gyrus in the hippocampus) can form new
neurons from neural stem cells (NEUROGENESIS) This can be facilitated by environmental
and mental stimulation.
Neuroplasticity: When an area of the brain has been damaged, new connections are formed
and different areas of the brain perhaps take over that function (no new neurons are being
created, but the connections between brain areas change)
Structure of neurons:
-Nucleus: contains DNA
-Cell body or soma
-Dendrites: tree-like branches that receive incoming signals from neighbouring cells
(receives the input)
-Axon: Part of the cell that takes the signal away (usually theres only 1 axon per cell). The
signal travels down the axon to the terminal buttons at the end (which will send the signal to
a neighbouring cell)
-Axon hillock: Where the cell body connects to the axon, where the cells decides if it's gonna
fire or not (depends on if a certain threshold is surpassed)
-Schwann cells: they form the myelin sheath, insulating the axon so the signal doesn’t get
lost and it travels faster (2m/s no myelin vs 200m/s with)
-Nodes of Ranvier: Tiny gaps in the axon’s myelin sheath. The electrical impulse that travels
along the axon jumps across them, speeding up the transmission of the signal (this is called
SALTATORY CONDUCTION)
-Axon terminal: in it, we have terminal buttons, where chemical neurotransmitters are stored.
When you have neighbouring neurons they don’t actually touch one another, there’s a very
tiny gap between the dendrites and axon terminals of the cells. This is called synaptic cleft or
synapse (this was discovered by Santiago Ramon y Cajal) One cell can synapse with
multiple cells.
Spatial summation: The dendrites receive lots of simulation from different cells.
Temporal summation: One cell continually stimulates the neighbouring neuron.
The cell will decide whether to fire or not. If it fires, it will send an electrical impulse down
along the axon and to the synapse (this is the action potential), but the electrical impulse
can’t jump across the synapse. In the synapse, there is a different type of signal: a chemical
, Cognitive Neuroscience (Lectures 4-9)
one.
Neurotransmitters are the chemicals that are released from the pre-synaptic cells into the
synapse. They will travel across the synapse and attach to receptors in the post-synaptic
cell, stimulating the dendrites of the neighbouring neuron.
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