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Cognition PSYC 364 > 2. Neuroscience and Connectionism > Flashcards

2. Neuroscience and Connectionism Flashcards

1
Q

phrenology

A
  • first to offer thoery of localized function
  • regions of the brain performed particular activities
  • destruction of a given area decreases/eliminates function
  • individual’s defined on the basis of the activities of numerous regions
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2
Q

endocast

A

was assumed that if we can’t open the skull, skull shows shape of the brain

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3
Q

failure of phrenology

A
  • postulated that the skull refelcted the extent to which each function was developed (e.g. larger bumps =more developed faculty)
  • regions were not as well-defined as phrenology believed
  • more generally, intensely local account of brain function also appears to be incorrect; processes are distributed and plastic (flexible - if brain is damaged, we can still recover function)
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4
Q

levels of neural function

A

neuronal
- a single, or small set of neurons
neural systems
- large set of neurons that perform specialized function
- typically referred to be a collective name (visual cortex, amygdala, dorsolateral prefrontal cortex)

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5
Q

neuronal communication refresher

A
  1. presynaptic neuron transmits signal
  2. postsynaptic neuron receives signal
  3. excitatory synapse increases likelihood of firing
  4. inhibitory synapse decreases likelihood of firing
  5. action potential
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6
Q

visual system

A
  • rods and cones = activated as photons hit the back of the eye
  • bipolar cell receives the signal and transmits it to the ganglion cell
  • ganglion cell receive info from many receptor cells
    eyes and brain
  • signals from rods and cones sent through optic chiasm to primary visual cortex
  • sensation from one side of the eye = transmitted to the contralateral side of the brain
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7
Q

language

A

Wernicke’s area
- comprehend meaning of words
Brocas’s area
- production of words
Wernicke and Broca’s area create a circuit together; stimulus (speech) received and processed, usually generating a response (speech)

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8
Q

celia

A

ear cell

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9
Q

representing information in the brain

A
  • redundancies are built in to neuronal representations
  • stable pattern of activation create LTM
  • there is no grandmother cell
  • patterns give our world meaning
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10
Q

role of neural redundancies

A
  • allow set of neurons to perform multiple tasks at once
  • different patterns of neural activity generate the same outcome
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11
Q

levels of function: neuron

A
  • small information processors
  • use input-output
  • can be highly plastic
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12
Q

levels of function: systems

A
  • perform specific function efficiently
  • some innate, some can be learned
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13
Q

levels of function: cognition

A

numerous systems function togeher to give rise to attention, memory, and decision making

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14
Q

firing patterns of cognitive function

A
  • if patterns of activation store info, we can examine them to determine what cognitive processes are associated with regions of the brain
  • look at _____ to find a consistent story
    1. accuracy
    2. RT
    3. patterns of activation (can be temporal or spatial)
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15
Q

a bit of physics (radiation, substances, magnetism)

A
  • radiation entails that energetic particles move through space
  • different substances have different densities with certain materials absorbing (or reflecting) energy differently
  • magnetism: dependent on the electric charges/currents running through an atom; magnetic fields can be altered with the introduction of current
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16
Q

neuron waste

A
  • neurons expel waste
  • allows to examine patterns of activation and their proxies
  • these regularities can be used to examine what regions of the brain are active during a task
  • more activity = more blood to that region
17
Q

neuropsychological evidence for cognition

A

electrical signals
- Galvani’s experiments with muscles
- ERP (event related potential)
brain damage
- Phineas gage: lack of ability to control emotions, impairment of executive function, change in personality
cerebral blood flow (CBF) and oxygen use (BOLD)

18
Q

ERPs

A
  • electrical signal from the brain caused by neurons firing
  • regions fire at different rates depending on stimuli that is presented
  • can be measured with EEG (electroencephalography) or MEG (magnetoencephalography)
  • EEG mainly for temporal (not spatial) because our skull is so thick
19
Q

CT scans

A
  • X-Ray Computed Tomography uses electromagnetic radiation
  • uses property of certain matter in your body to block x-rays, creating “gaps” in the resulting 2D images
  • these gaps represent structures and the 2D images can be assembled into a 3D image of your brain
  • assess where the underlying brain damage is
  • use is limited because x-rays are bad for you
20
Q

PET scans

A

Positron Emission Tomography
- uses biologically active molecule (similar to glucose)
- tracer emits positrons which are detected by a CT scanner
- from this, 3D model of mental activity at a given point in time can be created

21
Q

MRI

A

Magnetic Resonance Imaging assumes
- atoms have tehir own magnetic field, in combination with radio waves this field can be reversed
- by examining changes in this field over time, we can obtain a picture at a given moment of the behaviour of atoms within neurons
- given that no radioactive material is required, procedure is a noninvasive way of obtaining a picture of the brain

22
Q

fMRI

A

functional Magnetic Resonance Imaging
- has spacial and temporal resolution
- researchers found that hemoglobin was affected by a magnetic field in a different way depending on whether it was oxygen-rich or depleted of O
- given use of O by a cell = dependent on that cell activity , we can use blood flow as a measure of the activation of a given region during a certain task and see the changes over time
- has a lot of false positives if not done properly

23
Q

connectionism

A
  • one of the most successful models of human cognition
    1. collection of units (not necessarily neurons)
    2. units have 2 discrete states
    3. feedback used from outcome
    4. learning rate adjustment determines speed of acquisition of info
  • biologically more realistic than other systems, like functionalism
24
Q

basics of connectionism

A
  • for any given task, some layer of nodes (neurons) is activated when presented with a stimulus
  • pattern of activation becomes associated with the stimulus through feedback
  • the weights between units (strength and association) are adjusted each time the model completes a run
  • learning rate can be altered to simulate difficulty of task, length training, etc.
  • refer to slide 35
25
Q

neural properties of connectionism

A

benefits of connectionism stem from its similiarity to brian B
- complex network of associations of small units
- units can be inhibitory or excitatory
- units = either on or off (they fire or they don’t)

26
Q

parallel distributed processing

A
  • units = either on or off (they fire or they don’t)
  • e.g. bus coming - shape, colour, depth, etc. if it works all at once, RT increases
  • many neural connections may be active at the same time
27
Q

concerns with connectionism

A
  • units = too simplistic; they cannot represent info like the brain does
  • has generic units whereas brain has specialized cells and areas for processing
  • mechanism that produces feedback in connections is not supported by neurological studies
28
Q

neural synchronicity and memory

A
  • important for learning, memory and consicousness: global property
  • was hypothesized that a given global pattern of firing could be associated with an item in a memory list
  • refer to slides 38-39
29
Q

connectionism: interim conclusions… for now

A
  • connectionist models provide useful tools for understanding human learning and decision making
  • we must understand their assumptions and compatibility with the task we wish to model
  • these are limited in their ability to explain B
30
Q

Hebb rule

A
  • when an axon of cell A is near enough to excite a cell B and repeatedly takes part in firing it, some growth process/metabolic change takes place in one/both cells
  • such that A’s efficiency increases, as cell B is firing
  • idea that connection between two neurons takes place only if both neurons are firing at about the same time
  • has greatly influenced subsequent theorizing
31
Q

connectionism: identity theory

A

problem = multiple realizability is difficult

32
Q

connectionism: functionalism

A
  • problem = syntax does not lead to semantics
  • problem = not tolerant to damage
33
Q

serial processing

A

only one neural activity may take place at any one time

Cognition PSYC 364 (24 decks)

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