Physiology, Psychophysics and the Science of Mind Flashcards
what was trephining
Stone Age humans bored or chiseled holes into skulls of living individuals, perhaps to release supposed evil spirits or as a cure for headaches or bizarre behaviours, or as punishment
describe early representations of trephining
Bosch did a painting called “the extraction of the stone of madness” which is usually interpreted as an allegory for foolishness/stupidity –> metaphor for how insanity might be cured by removing the stone of madness
when did humans understand that the brain was an organ of importance
there is evidence that early homonids knew head injuries could cause disabilities or death –> these injuries were inflicted intentionally on animal prey and sometimes other homonids
who is credited with the recognition that the brain is the organ of intelligence
Hippocrates
when to anatomical treatises (written work) on the brain date to
anatomical treatises on the brain and sensory organs (particularly the eyes), including diagrams based on dissections, are more than 2500 years old
when was a productive time for advances in brain anatomy
the Renaissance
what did Leonardo da Vinci do during the Renaissance
he dissected more than 300 cadavers (many of whom were executed criminals) and made detailed drawings of the brain –> incredible accuracy in drawings that hadn’t been seen before
who was Andreas Vesalius
he made significant advances in neuroanatomy and described the human brain in great detail with words and images –> published his drawings, unlike da Vinci
what were some important milestones during the Renaissance
- discovery of cerebrospinal fluid
- differentiation between white and gray matter in the cortex
- naming of brain areas (including the pons and hippocampus)
- discovery that the image on the retina was inverted
when was the microscope invented and by whom
- seventeenth century –> Anton van Leeuwenhoek
- created lenses of sufficient magnification to see neurons
describe Leeuwenhoek’s contributions to neuroscience
he created the microscope with lenses sufficient enough to see the “invisible” world of unicellular organisms in a pond of water –> also sufficient enough to see neurons
describe Leeuwenhoek’s research on the eye
he used the microscope to study the tissues of the eye, especially the retina –> might of been the first to see photoreceptors for vision (rods and cones)
when did understanding of brain anatomy develop
there was some better understanding with the use of the microscope and better dissection/preservation techniques in the 17th c., but more significant understanding of the areas of the brain and nervous system required the technological advances of the 19th c.
what inspired developing neurological work
there were medical implications, but also philosophical implications (speculation about the nature of the mind and senses)
what did psychophysics seek to measure
the relationship between events in the physical world and the psychological perception of those events
what is an fMRI
a device that provides images of blood flow or other metabolic changes in an intact, functioning brain in a conscious human subject –> allows the comparison of brain activity with ongoing mental activity (e.g. recording images of the brain’s functioning while the subject is solving mental arithmetic problems)
what were some of the key questions in 19th c. neurophysiology that were important to research in psychology (3 questions)
- cortical localization of function –> do different areas of the brain serve different functions, or are they non-specific
- specificity of the nerves –> do certain nerves carry information of only one kind?
- speed of nerve conduction –> how fast does information travel
describe the question of cortical localization of function
do difference areas of the brain, marked by different tissue structure, texture, density and cellular composition, serve different functions? Or are the functions of the brain nonspecific and spread across the cortex
describe the question of specificity of the nerves
might certain nerves carry information of only one kind, or did nerves carry all kinds of information
what initiated the discussion on cortical localization of function
Gall’s work in anatomy and phrenology (crainoscopy) –> known for his work on the cranial nerves, brain stem anatomy and differentiations of neural functioning of white and gray matter in the cortex
how did Gall’s ideas on phrenology begin
he claimed that his ideas on it began when he was 9 years old and noticed a classmate who showed good verbal memory and had bulging eyes –> noticed in other people a correlation between bulging eyes and verbal memory, and assumed that the growth of the frontal lobes was excessive in these individuals, causing their eyes to bulge
what did Gall notice in his patients during his work as an anatomist
he noticed clinical cases where individuals had suffered head wounds and consequently showed certain personality changes or intellectual deficits as a result
describe Gall’s system of phrenology
he identified 27 different faculties that resided on the cerebral cortex
why was phrenology accepted by the medical community for a decade
- there was already work on nerves showing specificity of function, so it made sense to them that the cortex would also show specificity
- neuroanatomical studies by Gall himself showed anatomical differences across the cortex, so why not functional differences as well
describe Flourens’s response to Gall’s phrenology
Flourens was a French neuropsychologist who set out to test the claims of phrenologists using animals (because gall argued that 19/27 faculties could be found in animals) –> removed brain tissue from these areas and then observed losses of function
when was phrenology rejected by the medical community in North America and Europe
the 1860s
describe what Flourens found in his loss of function experiments in animals
- Gall claimed the cerebellum controlled sexual behaviour, so Flourens lesioned this area and observed deficits in motor behaviour but not sexual activity
- As he made larger and larger lesions in the brain, he noted loss of function across many different behaviours –> concluded that behaviour control was spread widely across the brain and was not localized (this also was not correct)
what did Bouillaud contribute to the study on cortical localization
he made his case for functional locations in the brain, emphasizing an anterior portion of the cortex responsible for speech –> these claims were supported by Aubertin (his son-in-law)
describe Aubertin’s contribution to cortical localization of function
- 1861 meeting of Anthropology –> made a case for a speech centre and noted how it was supported by his own clinical research and would be solidified through autopsies on patients with loss of speech
- Broca attended this meeting
describe the work of Broca
- he encountered a patient in surgery who was suffering from cellulitis (skin disorder causing tissue inflammation) and couldn’t speak other than repeating the word “tan” but could still understand everything being said
- a few years earlier, the patient had also experienced gradual paralysis in his right arm/leg
- Broca performed an autopsy immediately after he died and suspected damage on the left side of the brain (because of the right side paralysis, and contralateral projection was already discovered)
what did Broca discover in his patient “tan”
- there was a hole in the cortex of the left frontal lobe –> tissue was deprived of blood supply for 20 years and died, causing the loss of speech –> tissue had dissolved and was carried away in the cerebrospinal fluid
- paralysis resulted from lesions elsewhere on the same side of the brain
- determined this area of frontal lobe was important for language
how did Broca increase the support for his claims that a particular area in the frontal lobe was important for language
he acquired a dozen more clinical cases demonstrating frontal lobe damage in the left cortical hemisphere (in around the same area as Tan)
what is Broca’s area
associated with the production of speech (expressive aphasia) but not the understanding of speech (receptive aphasia)
what is Wernike’s area
associated with the understanding of language (receptive aphasia) –> mediated in the left temporal-parietal cortex
what contributions did Hitzig & Fritsch make
they performed electrical stimulation studies of nerves (based on pre-existing understanding of electrical nerve impulses) in exposed cortices of dogs –> showed that a number of different voluntary movements occurred due to stimulation (e.g. movement of the front or hind leg, facial movements)
what did Broca’s work have in common with Hitzig & Fritsch’s work
both of the studies were reliably reproduced and showed evidence in support of localization of function (stimulating an area causes a specific movement, lesioning an area causes a specific loss of function)
who was the first to electrically stimulate a living human brain
- some evidence that it could have been Hitzig (but this is controversial)
- Barthalow is better accepted as the first to do this –> applied electrical current to the brain of a patient and reported movement in arms and legs was contralateral to stimulation of the brain
who was Ferrier
neurologist who published a book based on intensive studies on animals (particularly monkeys) –> used precise and systematic techniques, and produced highly detailed mapping of sensory and motor functions in the brain
What did Bell suggest through his research
he privately published a booklet stating that the spinal cord is made up of two kinds of nerves –> sensory nerves in the dorsal portion of the cord and motor nerves in the ventral part of the cord
describe the conflict between Bell & Magendie
Bell initially privately published the findings that the spinal cord is made of two types of nerves, and 11 years later Magendie published a similar discovery and claimed the discovery –> Magendie claimed he never read Bell’s booklet, but the dispute continued and eventually the law was just referred to as the “Bell-Magendie law”
what is the Bell-Magendie law
- afferent information from the senses to the brain is carried in the dorsal part of the spinal cord
- efferent information from the brain to the motor effectors is carried in the ventral part of the cord
- this discovery was important to later scientific psychology grounded in stimulus-response experiments
what are S-R experiments
stimulus response experiments
what is the law of specific nerve energies
discovered by Müller, the believe that each sensory nerve carries only one kind of sensory information, regardless of how the nerve is stimulated –> the same sensation can be produced by two types of external stimulation (a person would report seeing something both when light hits the eye or when physical pressure is applied to the eye)
describe the law of specific nerve energies using vision as an example
the same sensation can be produced by two types of external stimulation (a person would report seeing something both when light hits the eye or when physical pressure is applied to the eye) –> the optic nerve was stimulated in both cases and the result was a visual experience, thus the optic nerve only carries visual information regardless of how it is stimulated, but cannot perform the sensation of another nerve
was Müller the first to propose the idea of sensory nerve specificity
no, Bell made a similar argument in 1811, but Müller’s work was widely known in promoting the idea and providing evidence of the specificity of functional organization in the brain
did discoveries on cortical localization and nerve specificity provide evidence in support of the scientific validity of phrenology?
- phrenologists were correct about the idea that certain areas of the brain have specific functions
- they were wrong about which areas did what, and about the possibility of measuring brain growth from the surface of the skull
- these findings did not change the lack of evidence for the validity of phrenology
describe how Müller addressed the question of the speed of nerve conductance
he argued that the transmission was instantaneous, perhaps travelling as fast as the speed of light –> no reason to try and measure it because of its speed
who disagreed with Müller’s account of neuronal speed conductance
his student, Helmholtz
describe Helmholtz’s inventions in the field of optics
- created the ophthalmoscope –> observes the retina and is still used today
- invented the ophthalometer –> devices measuring curvature of the eye
- devised a stopwatch that measured time in smaller increments
describe Helmholtz’s theories and laws
- theory of colour vision
- theory of pitch perception
- law of conservation of energy (physics)
- musical theory
- new geometry
- speech synthesis
- meteorology
- draw plans for the workable telephone (with Bell)
why did Helmholtz begin studying nerve conductance
one of his friends in medical school (du Bois-Reymond) proposed that the nerve impulse was an electrochemical wave and the transmission time might be slow enough to measure
how did Helmholtz study on nerve conductance speed
he worked with the severed leg of a frog and his findings formed the basis of the measurement of reaction time –> stimulated one end of the nerve and measured the arrival of the impulse at the other end (as indicated by a twitch of the foot) –> found that the impulse travelled at 90 feet/second, clearly measurable not instantaneous
who worked in Helmholtz’s laboratory
Wundt –> he went on to use Helmholtz’s reaction time measure in his laboratory later in life, where he studied the speed of mental processes
what were some of the questions that inspired the introduction of sensory physiology
- how many senses are there
- are senses the same for everyone
- to what stimuli do people respond to
- what role is played by the physical components of the senses
- how is sensory information carried in the nervous system
- is there specificity of sensory function in the brain
what parts of sensation had already been investigated by physiologists
- organs of sensation
- stimuli of sensation (light for vision, sound for audition, chemicals for taste and smell, tactile pressure and temperature for touch)
- cortical areas for different senses
- some pathways from receptors to the brain
what was the first task of sensory physiology
discover the receptors (specialized cells that change energy from one form to electrochemical energy that was transmitted in neurons) –> those involved in “transduction”
what was known about the retina in 1851
- contains rods and cones
- colour perception differs across different retinal areas
- visual acuity better for images on certain parts of the retina than others
what is the Snellen eye chart
horizontal rows of block letters of differing sizes –> invented in 1862 and used to measure visual acuity
why was work on sensory physiology important
senses played an important role in writing on the “blank slate” of the mind
describe the progress of knowledge on sensation in the late 1800s
there was lots known about colour vision, depth perception, optical illusions, frequency of sound, timbre, taste buds, etc.
why did work on colour vision intensify after 1850
advances in sensory physiology and optical technologies
describe the trichromatic theory (or “young-Helmholtz theory”) of colour vision
there are three fibres in the retina that are differentially sensitive to red, green and blue light –> any spectral hue could be reproduced by some combination of these three colours
how did Helmholtz describe his trichromatic theory
he thought of it as an extension of Müller’s doctrine of specific nerve energies –> three different types of nerve fibres for each of the three colours, each of which would only conduct sensory information of only one colour
what was the young Helmholtz theory good at describing
multiple different colour phenomena like colour mixture and colour blindness
what was the young Helmholtz theory not good at describing
colour afterimages, complementary colours, black-white perception (achromatic colours) or the phenomenological importance of yellow as a primary colour
what did Hering contribute to sensory physiology
he proposed an alternative theory to colour vision from the Young-Helmholtz theory
describe the opponent process theory (or “Hering theory”)
there are three colour receptors (chemical substances in the retina) that can be either built up (anabolic process) or broken down (catabolic process) –> one for blue-yellow perception, one for red-green perception, one for black-white perception
What did Hering’s theory add to research on colour vision
- included yellow as a primary colour
- grouped colours via complementary pairs
what was determined about the usefulness of Young-Helmholtz’s and Hering’s theories of colour vision
Young-Helmholtz theory explained colour vision at the retinal level, while the opponent process theory better accounted for the way colour information was processed in the lateral geniculate body of the thalamus (major relay station from eye to V1)
describe the resonance theory of Helmholtz (or “place theory”)
based on knowledge of the basilar membrane in the cochlea of the inner ear –> membrane wide at one end and narrow at other, thus Helmholtz drew an analogy between its operation and that of a keyboard –> different frequencies have their greatest impact at different places on the membrane
describe how the function of a piano influenced Helmholtz’s resonance/place theory
argued that the basilar membrane was composed of a series of transverse fibres (like strings on a piano), and each of these fibres tuned to a separate frequency –> the brain would be able to discern whether a sound was low or high in frequency by information carried from different regions of the membrane
describe frequency theory (Rutherford)
argued that the firing of the impulses from the basilar membrane would match the frequency of the incoming sound (e.g. a tone of 1000 cycles/second would cause the membrane to produce a train of impulses at a rate of 1000/sec that were sent to the brain)
was Helmholtz’s place theory of Rutherford’s frequency theory more accurate
both of these theories were found to have problems and were modified by later research –> both theories remain valid for accounting for major aspects of auditory perception (but are modified from their original form)
what was considered to be a sixth sense during part of history
time perception, or “time sense”
how did sensory physiology progress as a field of study
continued to examine the roles of various structures and special topics in visual sense –> continued through the field of “physiological psychology”
what field of research dominated Wundt’s lab
sensation and perception –> at least 50% of work was in this area
what did Fechner gain insight about
he realized it was possible tom measure, with great precision, the relationship between the physical and psychological worlds –> attempt to solve the mind-body problem
describe an example that outlines how the physical and psychological worlds are not always the same
what is in the world is not necessarily what we perceive –> the movement on a movie screen looks real, but nothing is actually moving on the screen (just a succession of photographs)
what is the field of psychophysics about
measuring the relationships between stimuli in the external world (physical events) and the person’s perception and experience of those stimuli (psychological events) –> they are not the same, but they are related
what work did Weber do
he was a professor of physiology who began work in the field of psychophysics and became the first to publish work in that field –> mostly focussed on somatosensory perception (sense of touch)
what two important discoveries did Weber make
- the two-point threshold
- a psychophysical relationship that specified the perceived differences between the physical and psychological worlds (“Weber’s law”)
what kinds of questions did Weber’s research address
the relative sensitivity of different areas of the skin –> used a compass-like device with two points, and would touch participants with this device at various different lengths (while they were blindfolded) –> subjects were asked if they felt one or two points, and he would continue to extend the compass until they answered “two”
what is the two-point theshold for touch sensitivity
the distance required between the compass points for the subject to discriminate reliably between one and two points of touch
what did the two-point threshold lead Weber to conclude about the skin
he thought the skin was a mosaic of sensory circles, each of which was linked to a single touch nerve –> in some areas of the skin (e.g. the face), the circles were smaller meaning that nerve endings were denser and sensitivity was greater (and vice versa, with larger circles indicating poorer touch sensitivity)
describe how Weber discovered “Weber’s law”
he used weights to measure pressure, giving one weight (the “standard”) to a blindfolded subject, then would remove it and apply a second weight (the “comparison” weight) –> asked participants if the comparison was lighter, heavier, or the same and would determine the just noticeable difference
what is the just noticeable difference
also known as the “difference threshold” (discovered by Weber) –> the point at which the subject can reliably discriminate between two stimuli –> this difference is not constant but rather varies in terms of the absolute magnitude of the stimulus
what is the formula of the just noticeable difference
change in S divided by S is K (S is the standard weight, K is the ratio) –> this ratio applies to other sensory modalities other than weight
what is Weber’s law
expresses the amount of change necessary for the subject to perceive a stimulus as different (heavier, brighter, louder, sweeter)
what did Fechner contribute to the work of Weber
the just noticeable differences does not only represent a quantitative difference but also a psychological difference –> quantitiatively the JNDs are difference, but psychologically the experience is the same (perceived difference in set of weight is identical for the subject)
how did Fechner change Weber’s law
he re-formulated it into a logarithmic version written as S = k log R (S=perception of stimulus, k = perceived magnitude/intensity, R = actual physical value of the stimulus) –> called Fechner’s law or the Weber-Fechner law
what did Fechner’s insight lead to
research in psychophysiccs measuring the absolute threshold and the difference threshold
what is the absolute threshold
smallest value of a stimulus that can be detected
what is the difference threshold
the smallest difference between two stimuli that can be detected
what method did Fechner come up with
the method of average error (or the method of adjustment) that measured thresholds –> one of these was the “method of limits”
describe the method of limits
participant is presented with a series of sounds beginning with a sound intensity too low to be heard, and with each trial the intensity increases until the subject identifies hearing the tone –> then do it in reverse order until they report no longer hearing the tone (ascending and descending trials, respectively) –> these are done repeatedly and averaged to determine the threshold for intensity for that individual
describe the terms used to describe the physical vs psychological value of light
- physical = a wavelength of the light, perception = the hue of the light (psychological)
- intensity (physical) vs brightness (psychological)
