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PSYCH 1XX3 Chapter 4: Neuroscience Part 2 (Full Notes)
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  • April 22, 2024
  • 6
  • 2023/2024
  • Class notes
  • Michelle cadieux, joe kim
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Chapter 4: Neuroscience 2

Neuraxis: Line drawn along the spinal cord and through the front of completely through his head (destroying large part of his left
the brain frontal lobe)
● Helps to denote the direction in which the nervous system ○ Gage eventually recovered, but his personality
lies changed
● Straight line in many animals but bends forward as the spine ■ Before Incident: Capable, efficient,
enters the brain in humans athletic, intelligent, full of life
● Rostral: Front of line (towards head) ■ After Incident: Fitful, grossly profane,
● Caudal: Back end of line (towards tail) selfish, erratic, unreliable
● Dorsal: Top of line, top and back of head (structures above ○ Appeared unable to plan his future actions + was
neuraxis) constantly changing from one idea to the next
● Ventral: Underside of line, faces ground ○ Suggested that frontal lobes = responsible for
● Medial: Structures close to centre of brain functions like planning + impulse-control (later
● Lateral: Structures farther away from centre of brain studies confirmed this)
● Cons of Clinical Lesion Studies:
○ After an extensive behavioural study of an
interesting patient, he might live for many years,
or the relatives may decline to give permission for
an autopsy when he dies
○ Rarely isolated to specific structures which makes
a more difficult task of assigning impaired
function to specific brain areas (can be overcome
with controlled lab studies examining specific
brain lesions induced in animal models)
Electrical Stimulation: Stimulating a part of the brain and trying to
determine what brain function is elicited (building anatomical map
related to function)
● Diff approach to determining brain function then
lesion/ablation studies
● Taken by Canadian neurosurgeon Wilder Penfield in a
famous series of experiments published in 1951
○ Performed brain surgery on epileptic patients to
Franz Joseph Gall's Theory of Phrenology: Idea that diff brain surgically remove the focus of the epileptic
functions = located in diff areas activity from the brain
● Not based on any scientific evidence ○ Anxious to avoid cutting into the eloquent areas of
● Asserted that diff mental attributes (ie benevolence, hope, the brain/eloquent cortex (areas where damage
intelligence) were located in diff sub-organs of the brain, would lead to paralysis, loss of language ability or
and these sub organs would grow with the use of that loss of sensory processing)
facility ○ While patients were under local anesthesia, he
● Believed that the growth of these sub-organs could be used an electrical probe to stimulate various parts
measured by looking at the shape of the skull of the brain, while asking the patients what they
● However, external shape of skull has almost nothing to do were feeling
with internal conformation of the brain (theory was ○ Through this, he was able to map out the sensory
eventually discredited) and motor areas of the brain + identify other areas
● However he brought the attention of more reputable ie where stimulation led to the vivid recall of past
scientists to the idea of the localization of function memories
Lesion/Ablation Studies: If a certain area of the brain is ■ If an area of the visual cortex was
damaged/removed, and a certain function of the brain is lost (ie stimulated, a patient reported seeing
memory, vision), that structure can be associated with that brain flashes of light
function (simple idea for studying brain function) ○ General features of brain maps = very similar
● Experiments done on animals (unethical on humans) across patients but exact details = vary quite
● Ex: Pierre Florens in 1825, developed techniques for considerably
surgically removing/ablating parts of pigeons’ brains + ○ Maps = supplemented by a battery of other
studying the results functional brain studies performed prior to surgery
○ Discovered that removal of the cerebellum ● Animal studies provide even more detailed info about the
affected the birds’ motor coordination, removal of operation of the living brain by recording brain activity with
the medulla interfered with vital functions (ie microelectrodes
heartbeat, respiration) ○ Info about action potentials (how ions flow during
● In humans, patients with accidental brain damage are this time) + membrane dynamics = obtained by
examined to determine both the site of the brain damage inserting microelectrodes into the axon of the
(during autopsy) and the nature of the functional changes in giant squid, stimulating the axon and recording
their behaviour activity (done by physiologists Alan Hodgkin +
● Ex: Phineas Gage (a railroad construction foreman) survived Andrew Huxley in 1952)
an accident in 1848 where a large iron rod was driven

, Chapter 4: Neuroscience 2

■ Diameter = quite large = up to 1 mm (an ■ Tissue is placed inside of a very strong
adaptation that speeds up the magnetic field + excited by a radio
transmission of the action potential frequency pulse so the molecules in the
since neurons in squids + some marine body vibrate at a certain rate, emitting
animals lack myelin) their own radio frequency waves
● Intracellular Recordings: Recording taken from inside a cell, ■ An antenna (head coil) picks up these
measuring the voltage/current across the cell membrane radio waves and records them for
while task is performed/stimulus is presented computer analysis
○ Possible because today we have microelectrodes ■ Diff molecules produce slightly diff
with tip diameters of less than a micrometre (can radio waves (computer decodes this
be inserted through the cell membrane of a single info, producing exquisitely detailed
cell of a living animal without causing undue pictures of diff slices of the brain)
damage) ■ Pro: Determines diffs between diff
○ Single-Unit/Single-Cell Recordings: The tissue types (ie grey and white matter)
responses recorded by these electrodes ■ Con: Takes much longer & is more
Extracellular Recordings: Groups of larger electrodes may also be expensive than CT
inserted into brain tissue to obtain extracellular recordings (quite ● Functional: Techniques that allow us to learn things about
common in research, best used on brain tissue of active + conscious brain function, neuron activity, etc.
animal) ○ Positron Emission Tomography (PET): In order to
● Recorded responses from array of electrodes = processed by find where the glucose is being consumed
computer to separate the individual action potentials from (because neurons in that area are firing action
any cell bodies that are near the electrode tip (allows activity potentials at an elevated level, so they require
from several cells to be simultaneously recorded) more energy than less active areas) a person is
○ Ex: The activity of single cells in rats was injected with radionuclide/radioactive tracer
recorded using this technique which led to the (mildly radioactive isotope of glucose/oxygen,
discovery of place cells (cells that would fire only very short half-life, will decay back into
when the rat was in a certain area of the cage, non-radioactive form in very short time, typically
located in the hippocampus) less than an hour)
■ Hypothesis from this = a cognitive map ■ Each time a radioactive particle decays,
of the environment is located in the it emits 2 positrons that shoot out in
hippocampus of the rat opposite directions
Neuroimaging: Both structural and functional scanning can tell us ■ A ring of detectors around the
important info about our brain individual’s head detects the positrons +
● Structural: Techniques to help describe the a computer calculates the exact location
structure/physical properties of the brain (without any of the positron emission
surgery to open the skull) ■ In this way the amount of glucose being
○ Computed Tomography (CT): Patient’s head is used by each brain area can be
placed in a ring containing an x-ray emitter + calculated, giving us an image of the
detector on opposite sides, ring rotates while amount of brain activity in a particular
emitter passes x-rays through patient’s head to area
detector, detector's response is recorded from all ■ This image = typically overlaid on a
angles through the patient’s head + computer is picture of the individual’s brain anatomy
used to reconstruct an image of the brain recorded from an MRI scan
■ Pros: Distinguishes diff tissue types to ■ Pro: Helpful for learning about how
some extent + shows areas of damage brain function relates to cognitive tasks
due to stroke if image is taken early such as language and memory
enough + relatively quick & inexpensive ■ Cons: Production of radionuclides =
+ often helpful to diagnose brain very expensive (requires atomic particle
injuries accelerator) + must be used almost
■ Cons: Does not show tumours unless immediately (half-life is very short) +
they are large enough to distort the radionuclide must be injected into an
underlying structure of the brain artery (relatively safe but not completely
(tumour tissue and normal brain tissue non-invasive) + person being scanned is
absorb about the same amount of x-rays) exposed to a small dose of radiation (3-4
+ subjects individuals to a moderate to times that of a CT scan), posing a
high dosage of radiation (poses level of minimal cancer risk + ALL areas of
cancer risk) + relatively low resolution brain = a little bit active all of the time,
(makes it difficult to examine fine brain and therefore would emit some
anatomy) radioactive particles + only provides
○ Magnetic Resonance Imaging (MRI): Head of an limited specific functional localization
individual is placed inside a large ring information (ie while studying what
brain areas are active while a subject
listens to music, if the subject’s eyes are

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