Psy. 120.3 September 17 2025
Psy 120.3 Lecture 3 Neuroscience & Behaviour Part Two
Brain Structure and Function: An Overview
For this course, our primary focus will be on the mid- and upper-brain areas.
Medulla: An extension of the spinal cord into the skull that coordinates heart, circulation, and respiration.
Reticular Formation: regulates sleep, wakefulness and levels of arousal.
Cerebellum: a larger structure of the hindbrain that controls the motor skills. (Not to be confused with the motor cortex).
Pons: relays information form the cerebellum to the rest of the brain
The tectum and tegmentum are two principal subdivisions of the midbraine, separated by the cerebral aqueduct. The tectum is the "roof" or posterior part of the midbrain, containing the superior and inferior colliculi.
The superior colliculus (SC) integrates sensory information, especially visual and auditory, to orient the head and eyes toward stimuli, a process crucial for detecting moving objects and initiating defensive reactions.
The inferior colliculus (IC) is primarily involved in the auditory pathway, processing sound localization, frequency and other acoustic features before relaying information to the thalamus for further auditory processing.
The cerebellum contributes ot the fine-tuning of behavior, smoothing our
actions to allow their graceful executing rather than initiating the actions. This is the location of the Purkinje cell, and recent research, capitalizing on advances in brain imaging, reveals the cerebellum is involved in a much larger range of cognitive, social, and emotional functions beyond motor control. (Diedrichsen, King, Hernandes-Castillo, Sereno & Ivry, 2019).
The cerebellum has evolved since our first primate ancestors came down from the trees. The arch of the cerebellum is part of the vestibular system, responsible for balance and equibrium in movement.
The anterior (forward) part of the cerebellum is called the paleocerebellum and is much older.
The posterior (rear-ward) part of the cerebellum is called the neocerebellum. In evolutionary terms it is much newer, having to deal with movements such shoulder twists (for curve balls, etc.) and speech. Our ancient ancestors, especially Homo Ergaster, could not throw a curve ball, or speak using vowels.
What is important to note here is how conservative Mother Nature is. She never throws away what works, but adds to and enhances already successful structures.
Subcortical structures: Areas of the forebrain housed under the cerebral cortex near
the center of the brain. Usually known as the limbic (ring) system. The main area of concentration for pharmaceutical therapies.
Cerebral cortex: outermost layer of the brain, visible to the naked eye and divided into
two hemispheres--left and right.
Finer Detail: The Subcortical Regions
The thalamus is a paired gray matter structure of the diencephalon located near the center of the brain. It is above the midbrain or mesencephalon, allowing for nerve fiber connections to the cerebral cortex in all directions — each thalamus connects to the other via the interthalamic adhesion.
The thalamus: relays and filters information from the senses and transmits the information to the cerebral cortex. However, the thalamus actively filters sensory information, giving more weight to some inputs and less weight to others. It also closes the pathways of incoming sensations during sleep, providing a valuable function in not allowing information to pass to the rest of the brain. The thalamus filters all the senses except smell, which has direct connections to the cerebral cortex, indicating its evolutionary age.
Hypothalamus (below the thalamus) regulates body temperature, hunger, thirst, and sexual behaviour. Lesions here can lead to overeating or starvation. If you are female, when you think about sex, messages from your cerebral cortex are sent to the hypothalamus to trigger the release of the hormone oxytocin, whose main function is to facilitate childbirth. This can also be stimulated from high butter-fat double chocolate ice cream, but only if you are female.
Pituitary gland: the master gland of the body's hormone-producing system, releasing hormones that direct the functions of many other glands in the body.
Limbic system: composed of the hypothalamus, hippocampus & amygdala; involved in motivation, emotion, learning & memory.
Hippocampus: critical for creating new memories and integrating them into a network of knowledge so that they can be stored indefinitely in other parts of the cerebral cortex. (Note: there is no single place in the brain where a memory is stored. Memories are recalled dynamically, assembling encoded neural messages from various parts of the cerebral cortex.) Individuals with damage to the hippocampuses (there is a left and a right one) can acquire new information and keep it in awareness for a few seconds, but as soon as they are distracted, they forget the information and the experience that produced it.
Amygdala: a part of the limbic system that plays a central role in many emotional processes particularly the
formation of emotional memories; the 'fear center' of the brain. It attaches significance to previously neutral events that are associated with fear, punishment, or reward. When we are in emotionally arousing situations, the amygdala stimulates the hippocampus to remember many details surrounding the situation.
Basal ganglia: a set of subcortical structures that direct intentional movements.
Corpus callosum: a thick band of nerve fibers that connects large areas of the cerebral cortex; supports
communication of information across the hemispheres.
Finer Detail: The Cerebral Cortex
The functions of the cerebral cortex can be understood at three levels: the separation of the cortex into two
hemispheres; the functions of each hemisphere; the role of the cortical areas.
Each hemisphere controls the functions of the opposite side of the body, or contralateral control.
The largest of the commissures is the corpus callosum, which allows information received in the right hemisphere to pass across and be registered (virtually instantaneously) in the left hemisphere.
The occipital lobe processes visual information. Sensory receptors in the eyes send information to the thalamus, which in turn sends it to the primary areas of the occipital lobe. When you hear of Neanderthals having larger brains than we do, it is this lobe.
The parietal lobe carries out functions that include processing information about touch. As a main role of the
parietal lobe is spatial processing, its involvement in mathematical thinking seems consistent with reports from school teachers that abilities at spatial reasoning are good predictors of gifted children's prowess at mathematics.
The somatosensory cortex represents the skin areas of the contralateral surface of the body.
Temporal lobe: responsible for language
Frontal lobe and association areas: thinking, planning, memory & judgment.
Finer Detail Yet: The Association Areas
Association areas: composed of neurons that help provide sense and meaning to information registered in the
cortex. Association areas weave together the threads of information in various parts of the cortex into a meaningful perception of the world.
A misunderstanding of the function of association areas and their relationship to the rest of the body is the source of the 'we only use 10% of our brains' myth. Most neuronal connections are inter-neural, that is neurons communicating with other neurons, rather than sense organs or muscles.
Neurons in the primary visual cortex are highly specialized: for example, horizontal orientation,
movement, human vs non-human forms.
Neurons in the primary auditory cortex register sound frequencies, but areas in the temporal lobe allow those sounds to be given meaning.
Mirror neurons are active when an animal performs a motor behavior, and also when the animal observes another animal of its own species performing the same behavior. Mirror neurons aid in recognizing the goal of that behavior and the outcome of that action.
Brain Growth: Neuroplasticity
The cerebral cortex displays (to a limited degree) neuroplasticity: functions that were assigned to certain areas of the brain may be capable of being reassigned to other (near) areas of the brain. Remember the homunculus as to how this works.
Extraordinary amounts of stimuli to a certain cortical area will re-organize it; there is greater plasticity within the motor cortex of professional musicians compared with non-musicians.
Physical exercise can increase the number of synapses, promoting development of new neurons in the
hippocampus the area of the midbrain or mesencephalon that initiates memory.
Neuroplasticity Gone Awry: Phantom Limb Pain
Phantom Limb Pain: a syndrome where a patient can feel their limbs moving, even in co-ordinated gestures.
Worse, some feel chronic cramps in missing limbs. Researchers stimulated the skin surface in various regions around the face, torso, and arms while monitoring brain activity in amputees and non-amputees.
Brain imaging displayed the somatosensory cortex activated. Areas of the face and upper arm activated an area in the somatosensory cortex once activated by the missing hand.
The reason for this plasticity: the cortical representations for the face and the upper arm normally lie on either side of the representation for the hand. New contiguous mappings happened. Some were quite precise: in some amputees, when specific areas of the facial skin were activated (eg: upper lip) the patient reported sensations in just one finger of the phantom hand.
A Mirror box: teaches amputees to increase voluntary control over their phantoms limbs (necessary for the
cramping problem). The phantom hand appears to respond to motor commands; with practice the patient can
become better at 'moving' the phantom in response to voluntary commands. Haiti earthquake victims in 2012 were greatly helped by this simple technique. Check out this scene from 'House':
https://www.youtube.com/watch?v=jPe8vdvftfE
Investigating the Brain
Much research in neuroscience correlates the loss of specific perceptual, motor, emotional & cognitive functions with specific areas of brain damage. These kinds of damages are called lesions.
Broca described a patient who had lost the capacity to produce complex spoken language, but not the ability to understand language, due to damage in a small area in the left frontal lobe. The patients could speak, however, in simple two-word sentences.
Wernicke described a patient with an impairment in language comprehension,but not the ability to produce speech, associated with damage to an area in the left temporal lobe.
'The strange case of Phineas Gage': his brain lesions are important in understanding between the cerebral cortex and the subcortical structures of the limbic system, especially the amygdala and the hippocampus.
Here are two examples from YouTube, the first short, the second long.
https://www.youtube.com/watch?v=F_-Xol6v3Ok
https://www.youtube.com/watch?v=oOkISlxST38
Disorders can threaten the ability of the brain to function, such as severe, intractable epilepsy. Iasemidis (1996) postulated that epilepsy might be best understood as a chaotic phenomenon (as in chaos theory, like Jurrasic Park). Chaotic systems, among other characteristics, can produce what appears to be random output. Another property of chaotic systems is that they may exhibit abrupt intermittent transitions between highly ordered and disordered states, that is, an epileptic seizure. In practice, this allows a researcher to analyze QEEG (Quantitative Electro Encephalo Graph) data using chaos algorithms.
For this class, think of a normal brain functioning according to chaos theory as in weather. A normal functioning brain is not a smoothly running machine (or computer) but a collection of several thunderstorms, each balancing the other out.
For example, seizures that begin in one hemisphere cross the corpus callosum to the opposite hemisphere and start a feedback loop that results in a 'firestorm' in the brain.
Split-brain procedure severs the corpus callosum, which affects lateralized perception The processing of basic sensory information is lateralized by being divided into left and right sides of the body or the space around the body. ... This means that the left side of the visual field is processed largely by the visual cortex of the right hemisphere and vice versa for the right side of the visual field. Fig. 3.20
Memorize Sperry's split-brain experiment for the next exam. Note: the figure is a snapshot of less than a second's time. • Also important: each optic nerve has a left and right visual field (contrast this to the misunderstanding of lateral perception that the left only gets info from the right).
Instead of hypothesizing a 'normal brain', we will embrace the concept of neurodiversity, the idea that there a natural variations in structures and functions that produce variations across individuals in cognitive, social, and emotional functions that should be distinguished from a disorder, or a damaged brain. (Baren-Cohen, 2017, known as the creator of the Autism Spectrum ).
Chimeric Faces: When a person with a split brain views a chimeric face of Brad Pitt (left) and Leonardo DiCaprio (right), her left hemisphere is aware only of DiCaprio and her right hemisphere sees only Brad Pitt. When asked what she sees, she answers, “Leonard DiCaprio” because speech is controlled by the left hemisphere. When asked to point to the face she saw with her left hand, she points to Brad Pitt because her right hemisphere is only aware of the left half of the picture.
This is a simplification, but for this class:
Left Visual Field: Light from your left visual field strikes the nasal retina of your left eye and the temporal retina of your right eye.
Right Visual Field: Light from your right visual field strikes the nasal retina of your right eye and the temporal retina of your left eye.
Left Visual Field --> Right Hemisphere --> Points with Left Hand.
Right Visual Field --> Left Hemisphere --> Talks and Points with Right Hand.
Investigating the Brain
QEEG & MRI
Quantitative Electroencephalograph: used to record electrical activity in the brain, with signals amplified several thousand times.
Brain activity can be monitored during different states of consciousness. There are differenct brain-wave patterns associated with different states of sleep.
Hubel and Wiesel inserted tiny electrodes into occipital lobes of anesthetized cats and observed the patterns of action potentials in individual neurons. They discovered that neurons in the primary visual cortex are activated whenever a contrast occurs between light and dark in the visual field. Each neuron responded vigorously only when presented with a contrasting edge at a particular orientation. Neurons in the primary visual cortex respond to particular features of visual stimuli, such as contrast, shape and color. These neurons are called feature detectors. Some fire only at 45 deg.; some at 0 deg., some at 90, ( a change in neurons every 15 deg.) Some visual processing neurons in the temporal lobe are activated only when detecting faces. Understanding why involves modern evolutionary psychology.
Brain Imaging
Computerized axial tomography (CAT): a scanner rotates a device around the head, taking a series of X-ray photographs, then software combines the images to produce views from any angle.
CAT High density skull = white; cortex = grey; fissures and ventricles = dark grey. Use to locate lesions or tumours, typically darker because they are less dense than the cortex.
Magnetic resonance imaging (MRI): uses a strong magnetic field to line up the nuclei of specific molecules in brain tissue. Brief but powerful pulses of radio waves cause the nuclei to rotate out of alignment. When the pulse ends, the nuclei snap back in line with the magnetic field and give off a small amount of energy in the process. MRI provides a clearer, higher-resolution image than CAT.
Functional Brain Imaging or Examining the Living Braiin
Positron Emission Tomography (PET): radioactive glucose in injected into the bloodstream, the brain then scanned by radiation detectors as the person performs conceptual or cogntive tasks. Areas of the brain that are activated demand more energy and greater blood flow, resulting in a higher degree of radioactivity in the region. See Fig. 3.24 for the difference between PET and fMRI.
Functional magnetic resonance imaging (fMRI) detects the difference between oxygenated hemoglobin and deoxygenated hemoglobin when exposed to magnetic pulses. Hemoglobin is the molecule in the blood that carries oxygen to our tissues, including the brain. When active neurons demand more energy and blood flow, oxygenated hemoglobin concentrates in the active areas.
This technology has become dominante because fMRI does not require exposure to a radioactive substance and it can localize changes in brain activity across briefer periods than PET.
FMRI can perform resting-state functional connectivity as patients are not required to perform a task; ti also measures the extent to which spontaneous in different brain regions is correlated over time. Used to detect the default network of frontal, temporal, and parietal lobes involved in internally focused cognitive activities.
For a little more detail, here is an honest use of Wikipedia: (Note the reference links)
Resting state fMRI (rsfMRI or R-fMRI) is a method of functional magnetic resonance imaging (fMRI) that is
used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an
explicit task is not being performed.[3][4] A number of resting-state conditions are identified in the brain, one of which is the default mode network.[5] These resting brain state conditions are observed through changes in blood flow in the brain which creates what is referred to as a blood-oxygen-level dependent (BOLD) signal that can be measured using fMRI.
https://en.wikipedia.org/wiki/Resting_state_fMRI
Insights from Functional Imaging
Fusiform gyrus: fMRI reveals strong activity near the border of the temporal and occipital lobes. If this area is damaged, propagnosia occurs: patients cannot recognize familiar faces, even when they can solve visual problems not related to faces.
When people look at sad pictures, significant activity is observed in the amygdala; also increased activity in the areas of the frontal lobe that are involved in emotional regulation. As a result, fMRI scans have confirmed that the frontal lobe plays a central role in regulating emotion.
However, the results of the fMRI studies of memory are presently inconclusive in determining true from false statements, so fMRI evidence is still inadmissible in a court of law.
Also, fMRI challenges notions about brain death and the vegetative state; Monti (2012) demonstrated that a 25-year-old woman with severe brain injuries had areas of the brain that activated when listening to ambiguous sentences, the same as normal volunteers. When she was asked to imagine playing a game of tennis, or walking through her house, her brain showed activity indistinguishable from normal volunteers. Consider what applying BrainNet might mean to such a patient.
A more recent fMRI study found using mental imagery tasks found evidence of willful modulation of brain activity or intentionality in 5 out of 54 patients with disorders of consciousness.
Diffusion Tensor Imaging (DTI) allows researchers to visualize white matter pathways in the brain, the fibre
bundles that play an important role by connectiing brain regions to one another. DTI measures the rate and
direction of water movement.
https://www.youtube.com/watch?v=NkxFLW3MRvQ
Transcranial Magnetic Stimulation
Transcranial Magnetic Stimulation (TMS) delivers a magnetic pulse that passes through the skull and deactivates neurons in the cerebral cortex for a short period. TMS pulses can be directed to particular brain regions, essentially turning them off, allowing the measurement of temporary changes in perception and behavior. Beckers & Zecki, 1995 discovered that magnetic stimulation of the visual cortex temporarily impairs a person's ability to detect the motion of an object without impairing that person's ability to recognize that object. This proves that motion detection and object recognition are processed in different areas of the brain. Moreover, it establishes that activity in the visual cortex causes motion perception. (Remember how shy we are about claiming causes.)
Schenk et. al. 2005 found that applying TMS to the specific area of the visual cortex responsible for motion
detection also impairs that ability to reach for moving objects, or for stationary objects when there is motion in the background. fMRI and TMS are now being integrated, allowing precise determination of brain locations of TMS effects. And as we saw in Web Article 2, QEEG and TMS are being integrated into BrainNet.
Functional Brain Imaging or Examing the Living Brain
Positron Emission Tomography (PET): radioactive glucose in injected into the bloodstream, the brain then scanned by radiation detectors as the person performs conceptual or cogntive tasks. Areas of the brain that are activated demand more energy and greater blood flow, resulting in a higher degree of radioactivity in the region. See Fig. 3.24 for the difference between PET and fMRI.
Functional magnetic resonance imaging (fMRI) detects the difference between oxygenated hemoglobin and deoxygenated hemoglobin when exposed to magnetic pulses. Hemoglobin is the molecule in the blood that carries oxygen to our tissues, including the brain. When active neurons demand more energy and blood flow, oxygenated hemoglobin concentrates in the active areas.
This technology has become dominante because fMRI does not require exposure to a radioactive substance and it can localize changes in brain activity across briefer periods than PET.
FMRI can perform resting-state functional connectivity as patients are not required to perform a task; ti also measures the extent to which spontaneous in different brain regions is correlated over time. Used to detect the default network of frontal, temporal, and parietal lobes involved in internally focused cognitive activities.
For a little more detail, here is an honest use of Wikipedia: (Note the reference links)
Resting state fMRI (rsfMRI or R-fMRI) is a method of functional magnetic resonance imaging (fMRI) that is
used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an
explicit task is not being performed.[3][4] A number of resting-state conditions are identified in the brain, one of which is the default mode network.[5] These resting brain state conditions are observed through changes in blood flow in the brain which creates what is referred to as a blood-oxygen-level dependent (BOLD) signal that can be measured using fMRI.
https://en.wikipedia.org/wiki/Resting_state_fMRI
Insights from Functional Imaging
Fusiform gyrus: fMRI reveals strong activity near the border of the temporal and occipital lobes. If this area is damaged, propagnosia occurs: patients cannot recognize familiar faces, even when they can solve visual problems not related to faces.
When people look at sad pictures, significant activity is observed in the amygdala; also increased activity in the areas of the frontal lobe that are involved in emotional regulation. As a result, fMRI scans have confirmed that the frontal lobe plays a central role in regulating emotion.
However, the results of the fMRI studies of memory are presently inconclusive in determining true from false s tatements, so fMRI evidence is still inadmissible in a court of law.
Also, fMRI challenges notions about brain death and the vegetative state; Monti (2012) demonstrated that a 25-year-old woman with severe brain injuries had areas of the brain that activated when listening to ambiguous sentences, the same as normal volunteers. When she was asked to imagine playing a game of tennis, or walking through her house, her brain showed activity indistinguishable from normal volunteers. Consider what applying BrainNet might mean to such a patient.
A more recent fMRI study found using mental imagery tasks found evidence of willful modulation of brain activity or intentionality in 5 out of 54 patients with disorders of consciousness.
Diffusion Tensor Imaging (DTI) allows researchers to visualize white matter pathways in the brain, the fibre bundles that play an important role by connectiing brain regions to one another. DTI measures the rate and direction of water movement.
https://www.youtube.com/watch?v=NkxFLW3MRvQ
Transcranial Magnetic Stimulation
Transcranial Magnetic Stimulation (TMS) delivers a magnetic pulse that passes through the skull and deactivates neurons in the cerebral cortex for a short period. TMS pulses can be directed to particular brain regions, essentially turning them off, allowing the measurement of temporary changes in perception and behavior. Beckers & Zecki, 1995 discovered that magnetic stimulation of the visual cortex temporarily impairs a person's ability to detect the motion of an object without impairing that person's ability to recognize that object. This proves that motion detection and object recognition are processed in different areas of the brain. Moreover, it establishes that activity in the visual cortex causes motion perception. (Remember how shy we are about claiming causes.)
Schenk et. al. 2005 found that applying TMS to the specific area of the visual cortex responsible for motion
detection also impairs that ability to reach for moving objects, or for stationary objects when there is motion in the background. fMRI and TMS are now being integrated, allowing precise determination of brain locations of TMS effects. And as we saw in Web Article 2, QEEG and TMS are being integrated into BrainNet.