Note
Studied by 8 peoplePSY 497 Exam 3 (Chapter 6 and 7)
A Brief History of Brain Science
Early Connections Between the Brain and Behavior
The earliest known text linking the brain to behavior is an Egyptian scroll (~1700 BCE) (Smith Papyrus).
The Smith papyrus- included info on how an ancient physician decided whether to treat wounded soldiers.
Ancient Egyptians recognized the brain’s role but they never fully grasped its significance.
Example: During mummification, the heart and other organs were carefully removed and preserved, but the brain was removed through the nostrils using hooks, and then disposed of
Early Theories on Brain Function
Plato (5th c. BCE): Proposed the brain housed the reasoning part of the soul.
Galen (2nd c. BCE): A physician and gladiator school worker, Galen provided empirical evidence by cutting a pig’s throat nerves, proving the throat nerves are connected to the brain and not the heart, so the voice must come from the brain rather than the heart.
He suggested nerves were hollow tubes through which “spirits” flowed.
Advancements in Brain Anatomy
Andreas VanWesel (Vesalius) (16th c) - father of human anatomy, noticed that the brain has 3 ventricles.
Back ventricle = Memory
Middle ventricle = the source of Thoughts and judgments
Front ventricle = Where all Sensory information was processed and was referred to as the (“common sense”)
He ignored the cerebrum, believing its folds resembled intestines.
Sympathetic Nervous System Origins
Galen observed reflexes in humans and animals, theorizing that body parts "sympathize" with each other’s distress.
This idea led to naming part of the autonomic nervous system the “sympathetic” system.
The Birth of Neurophysiology (Late 18th - 19th c.)
5 discoveries in the )late 18th and) 19th c. laid the foundation for neurophysiology:
Confirmation of the Cerebrospinal Axis (1784) – Jiří Procháska found that the spinal cord and central core control reflexes, leading to the bottom-up view of brain evolution. So the brain was finally viewed as the more advanced culmination of the spinal cord, not its progenitor. The spinal cord doesn’t come from the brain; the brain evolved from the spinal cord.
The Reflex Arc (1832) – Marshall Hall proposed the concept of the reflex arc which outlined stimulus-response pathways; later, in 1863, Ivan Sechenov proposed that all functions of the brain are reflexive. Even Ivan Pavlov expanded on this idea by interpreting his lab dogs’ drooling behavior through this prism- classical conditioning as a psychological reflex.
Localization of Brain Function:
Until the 19th century., brain researchers operated under the assumption of equipotentiality.
Several discoveries led to a different view of the brain - localization.
Jean Flourens (1820s) (considered the father of experimental brain science) demonstrated that different brain structures serve different functions. (e.g., cerebellum for fine motor movement, medulla for heart rate & respiration).
Paul Broca (1861) demonstrated that the left frontal lobe dominates speech production.
Karl Wernicke (1874) found a nearby but completely separate part of the left hemisphere that specializes in language comprehension.
The Discovery of Neurons – The brain & nervous system consists of individual nerve cells that are in near-constant communication.
Neurons store & Transfer info electrochemically- Nerve cells communicate electrically and chemically, refuting earlier ideas of “spirits” in tubes.
Electricity in the Brain
Emil duBois used electric eels as an analogy to demonstrate how human nerve signals could also be electric.
This led his close friend Hermann von Helmholtz to question whether nerves act like electrical wires or more like chemical batteries. He measured nerve speed (~108 km/h), showing they act like electrochemical systems rather than just wires.
The Rise of Neuropsychology
Neurophysiology- branch of physiology specializing in the study of the nervous system while neuropsychology is a branch of psychology specializing in the relationship between the brain & behavior.
In the 1970s, neuropsychologists became frustrated by the shortcomings of having to rely on brain injuries to map out localization. So, some neuropsychologists created a new sub-field, called cognitive neuropsychology. cognitive neuropsychology- a sub-branch of neuropsychology that relies on information processing models (instead of brain injuries) to demonstrate how the brain influences behavior.
*Emerged, using information processing models instead of brain injury studies.
Through the 19th century cadaver brains and studying the brain injury victims were the only ways to even partially map out brain functioning.
In 1924, Hans Berger became the first person to create a print-out of the elctrical activity emanating from a brain. He called his printout an ….? electroencephalogram
Brain Imaging Innovations
Electroencephalogram (EEG, 1924) – It has been quite successful in determining that the brain emanates numerous types of electrical waves. These discoveries have helped in several areas of research, most notably in the field of somnology. Hans Berger first recorded brain electrical activity, useful in sleep research and psychopathology diagnosis. Unfortunately, the EEG has been insufficiently accurate to aid in the localization effort.
Positron Emission Tomography (PET-scan, 1950s) – It was intended from the beginning to be used in part as a device for localizing brain functioning. Uses radioactive tracers to map active brain areas (less common today due to more accurate scanners and newer tech).
Magnetoencephalography (MEG, 1968) – In 1968, Illinois physicist David Cohen became the first to measure MEG signals. Instead of measuring electrical activity through the scalp (~EEG), MEG measures the magnetic field surrounding one’s head using this 300-sensor helmet. As originally constituted, MEG was not a particularly sensitive or accurate technique. This process has dramatically over the decades.
Functional Magnetic Resonance Imaging MRI (fMRI) – Another magnetic imaging technique that measures blood flow rather than brain waves or magnetic fields around the head. Tracks blood flow to map brain activity.
Both Pet-scan & fMRI are hemodynamic
Hemodynamism- the study of blood movement
fMRI works by determining how oxygenated the blood is in different areas of the brain.
As with the PET-scan’s gamma rays, the more oxygen used, the more active the brain area
Also, all MRIs use radio waves, and so are capable of measurement at the atomic level
Transcranial magnetic stimulation- Device that creates “virtual lesions,” watts temporarily disrupt the functioning of a precise brain area by inducing a weak electric current in the local neurons.
TCMS has several advantages:
TCMS has pinpoint control in creating these “virtual lessons,” so.. the disruption to localized brain functioning—- i.e. collateral damage is very limited
The disruptive effects are temporary.
Other benefits of TCMS
Recommended procedure for localization
Because of cost, use an fMRI to determine which general brain area you should investigate, then...
Use TCMS to confirm a specific area’s involvement in the target behavior/experience/ phenomenonyou’’re studying
Although males have brains ~10% larger than females, this ratio does not hold across all brain areas.
One particular area in the frontal cortex is associated with higher order cognitive functioning.
On average, this tends to be disproportionately “bulkier” in females.
Certain areas of the limbic system – the seat of emotional responses – are also bulkier in females.
Females can better distinguish shades of color (e.g. purple paint at Lowe’s)
In addition, females are also generally better at facial recognition
Other brain areas are disproportionately larger in males.
E.g. the part of the parietal cortex involved in space perception -- navigating in space. Thus, males are better at spatial reasoning, including using (compass) directions…
although females are better at following directions (i.e. instructions).
Males also have a larger amygdala, which responds to emotionally-arousing info.
Differences have been found even at the cellular level.
E.g. females have a greater density of neurons in the parts of the temporal lobes that are associated with language.
This may help explain why women typically outscore men on tests of verbal fluency
Men and women also differ in the way we encode memories of emotionally arousing incidents, which comparative research demonstrates is traceable to the amygdala.
Larry Cahill et al. (2004) conducted PETscans on Ps while they watched graphically violent films.
A few weeks later, the Ps were quizzed on the films’ content.
As predicted, recall was directly related to amygdala activity in both men and women.
But there was a difference…
For some Ps, only the right amygdala was active; in others, only the left.
Upon closer inspection, it turned out that all the “rights” were men and all the “lefts” were women.
Initially, they had no idea what this meant or why it was true.
What should you do when you obtain completely unexpected results?
Carl Sagan: “ECREE:” “Extraordinary claims require extraordinary evidence.” So…
You need to replicate your findings.
Three subsequent studies all confirmed Cahill et al.’s results.
Eventually, Cahill recalled a theory dating to the early 20th c….
Cahill hypothesized that – if this type of hemispheric specialization is true, except in the limbic system rather than the cerebrum – men should be better able to remember the gist of a situation (the essence of it), whereas women should better remember the details (both relevant and irrelevant).
Larry Cahill is also the guy behind the recent “Sex Matters” campaign concerning research on sex differences in medications.
We’ve known about some racial differences for awhile – e.g. East Asians are more sensitive to many medications than are people of Caucasian or African descent. Where sex is concerned…
Ambien (insomnia med) takes twice as long for a woman’s body to absorb, and often doesn’t fully kick in until the next day. Half-doses are now typically prescribed for women.
Children’s aspirin[?]: 1/day may reduce p(heart attacks) except not in women…. plus, it increases p(internal bleeding) However, children’s aspirin does reduce the p(blood clot
When you apply the principles of cognitive neuropsychology (cf. slide 12) to studying mental disorders in terms of breakdowns in normal cognitive functioning, you’re doing cognitive neuropsychiatry.
(I’m going to try to tie together three seemingly distinct threads of research now. Here’s the first thread…)
What is a Capgras delusion? The false belief that a family member or close friend has been replaced by an impostor who looks exactly like that person. Although it occurs with some frequency in schizophrenia, it can also manifest suddenly following a brain injury
What is prosopagnosia? A condition where someone is unable to recognize familiar faces, usually following a brain injury, often involving the right fusiform gyrus
In 1984, Russ Bauer reported the case of a man who was unable to recognize anyone’s face -- including his own -- following a motorcycle accident. Bauer conducted an electrodermal conductance (EDC) test on the man while showing him photos of a number of faces…
Dual Processing
Despite the fact that the man was unable to identify any of the faces presented to him, the EDC test indicated that his skin often responded whenever he was shown the face of someone who should’ve been familiar, but not when shown the face of someone he wouldn’t have known anyway. Thus, individuals who have prosopagnosia may not recognize faces consciously, but they can exhibit a reflexive, physical, or even emotional reaction to them. This is (anecdotal) evidence of dual faceprocessing routes….
Can we be done with Freud now?
In 1990, Ellis & Young suggested that in such cases the “cognitive” route has somehow been severed while the “dermal” or “emotional” one has not. Thus, there’s really no need to resort to Freudian interpretations involving unconscious sexual conflicts. Any thoughts on how such a discrepancy might happen, though? Third thread… Is anyone familiar w/ “blindsight?
Blindsight
In amphibians, eye signals are processed in the limbic system. Even though humans & other mammals have evolved a visual cortex, the mammalian limbic system retains this primitive visual structure. If someone’s visual cortex (as opposed to their eyes) is damaged individuals say they can’t see. However,… If they’re seated at a table & instructed to reach for an object (previously) placed at some random spot on the table, they often reach exactly where it is… Also, when asked to judge the emotional expression on the face of someone sitting across the table, they’re able to identify it correctly at an above chance rate. Theydoespeciallywelliftheexpressionisoneofanger
BLINDSIGHT & DUAL PROCESSING
B/c the limbic system is not directly connected to the visual cortex, these individuals have no conscious awareness of an object’s location or a person’s facial expression. But those visual signals are processed by the amygdala, wh/ also assesses emotion in others. Blindsight is the ability to (visually) detect things w/o being consciously aware of them. Perhaps this helps explain the dual processing aspect of both prosopagnosia and Capgras delusions as well?
CHAPTER 7:
Are you more than “a pack of neurons?” (Crick, 1995)
How is your mind separate from your brain…or is it? This is the most fundamental issue in all of Psychology: The mind-brain problem Currently, there are three main schools of thought:
1. Dualism
2. Materialism
3. Philosophical functionalism
THE 3 VIEWS
Dualism
Oldest viewpoint
Most intuitively satisfying
Mind is somehow independent of the body
Materialism
Mind is just a by-product of the (physical) brain
Philosophical functionalism
Mind is information in the brain, which could theoretically be copied onto another template with a similar structure. So, continuing the brain-as-computer metaphor… ~brain as hardware; mind as software (cf. “Transcendence”)
What do we mean when we say “the mind?”
A person’s collective abilities to reason, feel, plan, remember, etc. That is What makes you “you”
Mind vs. soul? Spiritual part of one’s being
Is that different from the “thinking” part? Plato said it is. Most people have an almost instinctive sense that one’s mind (as well as one’s self) is somehow separate from one’s body. [e.g. my daughter*] *When my daughter was trying to go to sleep but she said her brain didn’t let her go to bed even though she wanted to go to bed. Why do you suppose that is?...
DUALISM & THE MIND
What about consciousness? Is that somehow different from mind and/or soul? One definition for consciousness: The collection of experiences, associations, memories, thoughts, & feelings that we’re aware of
Would that suggest that the mind includes more than just the conscious?
Does a dualist perspective provide for the existence of free will or exclude it? It provides for the possibility of it. According to German psychiatrist Henrik Walter in his (2001) book The Neurophilosophy of Free Will, certain conditions are necessary for free will.
CONDITIONS FOR FREE WILL
Walter proposed these three conditions must be met in order for a particular act to be b/c of free will:
1. The agent (individual/organism/robot?) could’ve chosen otherwise. No p(choice) no free will in that instance
2. No external force can be compelling the agent to act (literally forcing a hand; mind control, etc.).
3. The act must result from rational deliberation.
Agree? What about an off-handed decision or action, or something you say in the heat of the moment: “I didn’t mean it!” You said it. Who do you think meant it? Your homunculus?
Can we think of free will as existing along a continuum?
There are issues beyond that of free will that have led modern cognitive Psychologists to essentially ban dualism from models of cognitive functioning. What is the first issue?.
Problem #1: The mind-brain (interaction) problem
How can an independent mind (or soul) influence the brain? If they’re independent, how do they interact? What’s the mechanism? (Remember Descartes’ response?)
Problem #2: The existence of unconscious phenomena
Such as?
Reflexes, dreams, hypnotic experiences, distant memories you hadn’t thought of for a long time but which can be readily triggered, etc…
The more mental processes there are beyond conscious control, the less essential consciousness (& the mind?) seems to be.
Problem #3: The eventual disappearance of “mystery forces
What “mystery forces?”
Phlogiston- Originally proposed by the 17thc. German alchemist (there’s your first clue…) Johann Becher. A substance that supposedly exists in some materials but not others, to explain why some substances (e.g. wood) burn & others (e.g. rocks) do not
The vital force- Similar to phlogiston in that this was another substance that supposedly exists in some objects (e.g. plants) but not others (e.g. rocks, again) to explain why some things are alive and others are not.
MYSTERY FORCES
Æther- another proposed material that never panned out: the stuff that the atmosphere & all of space are supposedly filled with
Of course, astrophysicists have recently proposed that the universe is filled with “dark matter” and “dark energy” without knowing what those are, but at least there’s some evidence for that. The point of all this? Eventually, there always seems to be a materialistic explanation for all observed phenomena
MATERIALISM
the mind is nothing other than the brain in operation. (BR2013, p275)
Mind as an epiphenomenon
Synonyms for materialism: physicalism, reductionism, monism (all vs. dualism)
Materialism posits that the conscious mind – if it even exists – does not control behavior.
Defend that position logically…
Psychology research journals are filled w/ studies demonstrating how poor we are at predicting our own behavior.
Social Psychology alone establishes this in abundance….
TALK ABOUT REDUCTIONISM...!
Paul Churchland (1981)
Cal-San Diego neurophilosopher
Declared that the notion of a conscious mind is little more than a delusion.
Belief in a conscious mind can have very damaging consequences.
Richard Dawkins (1976)
Oxford biologist
Published The Selfish Gene
Proposed that natural selection is not about the survival of organisms, offspring, or even species, but the survival of...
SURVIVOR: DNA
The survival of DNA molecules
According to Dawkins’ thesis, humans & every other species (including COVID-19!) are merely vessels that DNA has diversely developed to perpetuate itself.
This aligns with the fact that humans share a large proportion of genetic material with other species.
Humans & chimpanzees: ~98.8%
Mushrooms & other fungi share ~50% DNA with humans, making fungal infections difficult to treat.
DNA in all living things – plants included – is composed of the same four nucleotides:
Adenine, Cytosine, Guanine, and Thymine
PROBLEMS W/ MATERIALISM
Problem #1: How can Materialism possibly be correct?
Just as with dualism, no one has yet proposed a fully satisfying explanation for how the human mind can be just a by-product of biology (i.e., an epiphenomenon) when it feels so much richer than that.
Problem #2: The Problem of Personal Identity
If a mind is just a collection of experiences within a particular (physical) brain, how do we reconcile this with the fact that the molecules making up our brain change completely over a lifetime, yet we retain a continuous sense of self?
Is DNA replicating a sense of self?
Problem #3: Materialism is very simplistic
There has to be more to it than that, doesn’t there?
Is that all there is?
DOOR #3: PHILOSOPHICAL FUNCTIONALISM
What is cybernetics?
Study of control & communication in electronic devices designed to replace human functions.
Cybernetics research demonstrates that information transcends the medium in which it resides.
Example: A flash drive remains a physical entity before files are uploaded.
Files can exist separately from the drive, just as a mind might be separate from the brain.
Philosophical Functionalism
Mind is separate from the brain (consistent with dualism) but does not exist in some ethereal realm (consistent with materialism).
Mind = information contained within the brain.
Using the brain-as-computer metaphor:
Mind = software programming that is continually revised and updated.
Brain = hardware.
Therefore, mind could be removable.
THE MARY PROBLEM
Proposed by Australian philosopher Frank Jackson (1982)
Thought experiment: Mary is a scientist raised in a black-and-white environment, studying vision.
She acquires all the physical information about color perception.
Question: When she sees color for the first time, does she learn something new?
If so, then her previous knowledge was incomplete.
Jackson argues that the mind must be more than just the knowledge in the brain.
THE ZOMBIE PROBLEM
Proposed by philosopher David Chalmers (1996)
Imagine: A twin of yourself, identical molecule for molecule, but lacking conscious experience. Chalmers calls this your “zombie”, this zombie will respond to any stimulus or situation exactly as you would, but won’t experience the richness and vividness (the “qualia”) of it that you would.
Chalmers’ argument:
If we can imagine such a zombie version of ourselves, consciousness must be more than just information.
Similar to the Mary Problem, this challenges materialism and philosophical functionalism.
ARE WE AWARE OF ANYTHING?
Numerous studies in social Psychology, memory research, S&P, etc., show that we are not aware of all elements in a situation.
Ben Libet (1985): Even our decisions to act occur before we are aware we’ve decided to act.
Experiment:
Ps asked to move a finger whenever they felt like it.
Measured:
Time Ps noted their decision.
EEG brain activity.
Actual movement.
Finding: EEG spiked before Ps consciously decided to move.
Suggests that the brain initiates movement before the conscious mind is aware.
WHAT OF FREE WILL?
Does this eliminate free will?
Libet (1999): Free will may still exist since we can stop a movement once underway.
Rejoinder: How do we know the brain/homunculus/DNA didn’t just change its "mind"?
THE GLOBAL WORKSPACE MODEL (GWM)
Purpose of consciousness?
To coordinate mental activities like a stage manager in a theatre.
Stan Dehaene et al. (2001):
Visual stimuli presented for varying durations.
Results: Consciousness = an information distribution network (IDN).
Key findings:
Most information processing occurs unconsciously.
Conscious awareness arises when information exchange across brain areas reaches a critical threshold.
Consciousness coordinates processing, assessing situations, evaluating options, and planning actions.
NOW BROADCASTING ON IDN...
When the visual sensation system was provided enough time to detect and process the stimulus, a network of neuronal reactions took place in numerous areas of the brain. This was -- apparently -- consciousness at work, serving as an information distribution network (IDN) throughout the brain.
The research of Dehaene et al. (2003) and Vic Lamme (2006) has led to the following understanding of the global workspace model (n=3):
Most information processing takes place unconsciously.
A continuous exchange of information among various brain areas activates the IDN. This sustained information exchange triggers the person to become aware -- or conscious -- of the environmental stimuli responsible for all the neuronal activity already taking place.
Conscious awareness is necessary to coordinate the processing required to assess the elements of a situation, evaluate possible options, and plan a course of action.
In other words, consciousness is not unlike your eyes and ears. Just as your eyes and ears sense what’s already going on in your external world, your consciousness senses what’s already going on in your internal world.
Neuroscientists are using this same model to understand why conscious processing is so rich and full of qualia, which may serve to help solve "the Mary problem."
KICK, PICK, & LICK
Friedemann Pulvermüller (2005):
Ps read action words: "kick," "pick," or "lick."
Findings:
Reading these words activated motor cortex areas specific to each action.
Brain processes language in a way deeply tied to physical experiences.
EMBODIED COGNITION
Broad, automatic cerebral activation when experiencing words, sights, sounds.
If Mary lived in a B&W world, she would lack the experiential context needed to fully grasp color perception.
FINAL QUESTION: CAN MARY LEAVE HER ROOM YET?
Understanding color is not just about acquiring knowledge but also about forming perceptual experiences.
Supports the argument that cognition is embodied rather than purely material or functional.