Chapter 2: Cognitive Psychology/Cognitive Neuroscience 1
Neuroscience and Behavior
Why Cognitive Neuroscience? Levels of analysis
Cells of the Nervous System – Basic components
• Neurons – send and receive information. Three basic types (easily seen in a spinal reflex arc): o Sensory: PNS → CNS Don't forget about the age old question of How do you find the direction of a vector?
o Motor: CNS → PNS
o Interneuron: Neuron → Neuron
∙ Information transmission:
o Electrical (within neuron)
o Chemical (between neurons)
• Glia (“glue”)
o 10X as many glia as neurons
• Covering of Axon
• Produce Myelin
o Many different types
o Play critical roles in nervous system
Neuron and Its Parts
∙ Dendrites: Receive messages from other neurons (tho
∙ Soma: Cell body; body of the neuron
∙ Axon Hillock: Action Potential starts here. We also discuss several other topics like What is exploratory data analysis explain with an example?
o Small Hill – nerve impulse
∙ Axon: Fiber that carries information away from the cell body of a neuron
∙ Myelin Sheath: Lipid (fatty) covering of some axons. Made up of glial cells
o Unmyelinated axons shorter and gray Don't forget about the age old question of What is the meaning of post-humanism?
o Myelinated axons longer and white
∙ Axon Terminal Branches with terminal buttons:
∙ Terminal Buttons (Boutons)
Neural Impulse: Resting Potential (RP) to Action Potential (AP)
∙ Potential: A difference in electrical charge across a membrane
o Two rules for action potentials: 1) All or none, 2) One-way
o Permeability: Permeable, Semipermeable, and Impermeable
∙ RP (~-70 mv): cell is negatively charged on inside (large charged organic molecules), positive outside (mostly Na+). Membrane is semipermeable: Permeable to K+, impermeable to Na+ ∙ Stimulation via dendrites to threshold (~-55 mv)
∙ AP (shift to ~+30 mv): Na+ channels (AKA “gates”) open and charge is reversed – more negative outside than inside.
∙ Repolarisation: a lot of K+ first pumped out (~-80 mv), then Na+ via Na+/K+ pump (back to RP -70 mv)Don't forget about the age old question of What is muscular dystrophy?
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Synapse: Microscopic gap between two neurons
• Neurotransmitter activity: (Presynaptic N. neurotransmitter molecules) ???? (Postsynaptic N. receptor site) • Neurotransmitter—Receptor Site Analogy: Locks and Keys
• key = the NT molecule
• Lock = receptor site
• Two forms of information
o Excitation – the information from A makes B more likely to “fire” (i.e.,
produce an impulse).
o Inhibition – the information from A makes B less likely to “fire” (i.e., We also discuss several other topics like Is nadh oxidized or reduced in electron transport?
does not produce an impulse).
• At any point in time a neuron will be processing both excitatory and
• Cleanup used NTs
o broken down by enzymes.
o absorbed back into the pre-synaptic neuron (reuptake).
Principle of Neural Representation
∙ In general – Simple to complex: Hierarchical processing (bottom-up)
o Particular neurons are triggered by very specific stimulus
o There is a particular neuron that is triggered when you see a particular person (specific coding) o Neuron pathways that have been destroyed will be created again by other existing neurons through exposure, practice, & repetition
∙ Feature detectors [edges] (e.g., Huber & Wiesel): Simple (orientation), Complex (orientation+location) ∙ How is complex information coded? We also discuss several other topics like What should an 18-month old be doing developmentally?
o Specific (one neuron) coding
o Population (many neurons at once) coding
o Sparse (selective group of neurons) coding
BUT – If all neural signals are the same why do some result in vision while others results in sound or touch? Synesthesia: If you experience one sensory occurrence you will also have another sensory occurrence at the same time (Experience visual synesthesia while experiencing auditory synesthesia)
∙ Nerves are made of bundled axons
∙ Non-synesthesic People’s neural pathways go to where they’re supposed to go (Visual to Occipital) ∙ Synesthesic People’s neural pathways are interfering with other pathways causing more than one sensation at once (visual touching temporal and occipital) – has genetic influence;
more on females and people with higher intelligence Methods of understanding brain structure and function
• Damage (Functional Neurology):
• Electrical Recording:
o EEG – Measure brain waves
o ERP – Evoked Response Potential
o Structure: CAT & MRI (magnetic not radiation)
o Function: fMRI (1st Picture) and PET (2nd Picture) positron emission tomography maps brain activity – useful in studying cognitive processes.
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Localization, Distribution, and the “Binding Problem”
⮚ Localization: Particular areas of the brain associated with particular behavior. ◊ Faculty Psychology (e.g., Franz Gall) – basis of Phrenology (different parts
of brain – visual, auditory, etc.)
◊ Solid evidence (functional neurology) developed in 19th c.
▪ e.g. of Phineas Gage (1848)
▪ Broca (1861) & Wernicke (1874)
▪ Aphasia: organic speech disorder (Broca’s Area)
▪ Wernicke’s Aphasia: organic speech disorder where people could not
◊ Experimental neurology. e.g.:
▪ Fritsch & Hitzig (1820)
▪ Penfield (1930 ????)
⮚ Distributed: Some cognitive processes (e.g., memory storage and retrieval) do not seem to be localized ◊ Binding: How are different components of a complete percept bound (linked) together? ◊ Dissociations, e.g., Agnosia, show this
A Few Cortical & Subcortical Structures (under the cortex)
⮚ Subcortical Structures of Forebrain – Limbic System
◊ Cortex – outer part (thick as a CD) Cognitive processing
▪ Folded up because it’s a meter long and it needs to fit
inside the skull
◊ Brain stem/hind brain – keeping heart going, muscling toning, etc.
◊ Thalamus – processing and routing of sensory information.
▪ Stimulus – thalamus – occipital, temporal, or etc.
◊ Medial Temporal Lobe (MTL) structures
▪ Hippocampus – necessary for processing and storing memories.
∙ Anterograde Amnesia – Henry M
∙ Spatial memory – memory of where things are
∙ Early stages of Alzheimer’s
▪ Amygdala – emotional states (fear); impact on memory.
◊ Basal Ganglia -- motor
*Lobes of the Cortex
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Examples of localization in the lobes (lots of double dissociations – damaged 2 areas of brain and impairs 2 functions)
⮚ Pre-frontal cortex
⮚ Frontal Lobe (+ prefrontal cortex): Executive control – decision, ADHD, OCD, Turret’s Syndrome ◊ Initiation and control of motor activity (e.g., apraxia)
◊ planning and judgment. (e.g., dysexecutive syndrome)
◊ Lower LH adjacent to the motor areas used for language production. Broca’s (Productive) Aphasia ◊ Working memory functions
⮚ Motor & (Somato)Sensory Cortex (mapped by Wilder Penfield)
◊ Primary motor cortex – responsible for motor actions
◊ Cerebellum – responsible for refined actions
◊ Somato Sensory – tactile information
▪ 2/3 of motor control are dedicated in the hands and face
▪ With Anesthesia can’t talk – because can’t feel when tongue is moving (fine tuned feedback)
⮚ Parietal Lobe
◊ Tactile perception, Spatial/body perception (Contralateral Control – left brain controls right side of body vice versa)
▪ Take in and interpret spatial information
▪ Know how far and near you are and where your body parts are (tactile feedback) ▪ e.g.,Sensory Neglect - neglect syndrome (usually in dominant hemisphere) – person with neglect syndrome is not aware of the other hemisphere/side of what he/she is looking at. (right picture) problem with body integration (not knowing your body part)
▪ Person ignores (neglects) information on contralateral side. Oob
▪ e.g., of RH parietal lobe damage causing visual sensory neglect for information on the left side.
◊ Lower LPL: Anomic Aphasia
⮚ Temporal lobe
◊ Auditory perception (upper ridge)
◊ Large association area evident with effects of different effects of
damage to different areas
▪ LH: Wernicke’s (Receptive) Aphasia – can’t understand what
information you’re receiving
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▪ Visual agnosia (near junction with occipital lobe)
▪ Prosopagnosia (poss. Related to Capgras Syndrome?) – cannot recognize human faces ▪ MTL – Anterograde Amnesia
◊ Processing visual information
◊ Damage e.g.
▪ Primary visual cortex – blindness
▪ Secondary visual cortex – color vision (acquired achromatopsia – cannot see color – left picture) – hemiachromatopsia – half cannot see color – right picture
⮚ “BlindSight”- (rare) blind but can still navigate
Dorsal and Ventral Streams