PSYC 213 Chapter Notes - Chapter 2: Brain Injury, Positron Emission Tomography, Implicit-Association Test
28 May 2018
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Chapter 2: Cognitive Neuroscience
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Brain: Organ of the Mind
• Investigation of relationship between brain & behavior
• Modules: parts of brain, each responsible for specific cognitive operations
Localization of Function
• Gall & Spurzheim: promoted phrenology --> study shape/size/protrusions of skull to determine
which parts responsible for which mental activities
o Argued that (1) brain is sole organ of the mind
o (2) Basic intellect & character is innate
o (3) Since individuals have different character and intellectual traits, must have different
brain areas responsible for various functions
• Thought that more developed function = larger brain region = larger protrusion on skull
o Can determine person's strengths & weaknesses based on shape of skull
o Not true, but important idea of function and region correspondence
• Localization of function
• Franz: studied effects of frontal lobe ablation in rats (small lesions)
o No effect on performance in memory maze task
o Concluded that as long as have sufficient brain tissue left, does not matter specific
location
o Opposed phrenology --mental processes include activity of whole brain, not functionally
specific
• Lashley: performance in maze not greatly affected by limited brain damage
o But performance decreased as difficulty of task / brain damage increased
o Law of mass action: learning & memory depend on total mass of remaining brain tissue
o Law of equipotentiality: although some cortical areas may become specialized for certain
tasks, any part of brain can, within limits, do the job of any other part in that area
o Analogy to electric sign; can display any message from bank of lights
Relationship between Mind & Brain
• Cognitive neuroscience draws for many other disciplines to generate integrated understanding
of mind
• Interactionism, epiphenomenalism, parallelism, and isomorphism
• Consciousness: what aware of at any point in time
o Mind: broader, encompasses consciousness + subconscious processes
Interactionism
• Descartes (1600s): mind and brain are separate --interact & influence each other at the pineal
gland
o Not widely accepted
o Dualism --Sperry more recently
• Monostic: mind cannot exist apart from a functioning brain
Epiphenomenalism
• Mind is by-product of brain processes, has no role in determining behavior
• Huxley: mind to brain is analogous to steam to locomotive
o Will not learn much about the brain by studying the mind
• Skinner also believed that consciousness was irrelevant to understanding behavior
o Libet: study showing that action can precede conscious experience
Parallelism
• Fechner: Mind & brain are two aspects of same reality --any event in mind is accompanies by
corresponding event in brain
o Operate in parallel
o Subjects record events in brain as introspect
Isomorphism
• Gestalt (form/configuration) psychologist Kohler: consciousness organized into coherent whole
o Experience and neural process have same pattern
o Not just point by point-by-point correspondence like in parallelism, resemblance in all
structural characteristics
o Mental events & neural events share same structure
• Necker cube: 3D cube seen differently depending on which surface focusing
o Constant stimuli but subjective experience changes
o When change what see, change in underlying brain process
• Kohler thinks due to fatiguing areas responsible for one representation
o Discredited
Methods in Cognitive Neuroscience
• Swanson: mind is most complex thing in universe, not understood
Animal Models
• Consider similarity between animal and human, cost, space, and ethical concerns of the
research
o Some argue that if there is any other way of obtaining same information, then animal
study not valid/ethical
• Study response to stimuli, consequences of lesions (also reversible like cooling)…
o Not necessarily applicable to human brain, but source of most of what we know
Behavioural Studies
• Study behavior and infer about structure & function of brain
• Stimulus-response and study of sensory systems
o Sensory system: set of distinct sensory receptors, neural pathways and brain regions
that translates physical world into perception
• Vision, audition, taste, smell, touch, vestibular
• Cannot identify specific link between behavior & brain mechanism using these studies
o i.e. Able to move eyes faster from A to B when object at A disappears from view --
disappearance leads to disinhibition of eye movement system (superior colliculus)
• After image after fixation moves constantly due to fixational eye movements
Studies of Brain Injuries
• Subjects with brain damage, analyze symptoms or deficits
• i.e. Broca's aphasia (left inferior frontal lobe) --unable to speak
o Wernicke's aphasia: unable to understand language, damage to word meaning
processing area (left superior temporal lobe)
