Cognitive Neuroscience

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Cognitive Neuroscience
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What are we doing with our brains right now?

• Feeling your chair
• Squirming (moving)
• Watching
• Listening
• Remembering
• Paying attention
• Sleeping
• Feeling anxious
• Feeling hungry
• What happens when you ask a question?

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The Brain

• Approx 3lbs
• 1 trillion cells
• 100 billion neurons
• ½ of neurons are in cerebellum
• Each neuron has 5000 10,000 synapses
• Males and females differ, but only slightly
• Neurons transmit signals at speed of about 2 m/s
• There are more possible connections in your brain
  than there are atoms in the universe

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Cognitive Neurosccience

• The cell
• Cortex
• Mid-Brain
• Hindbrain

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Cell Structure From an Information Processing
View
Dendrites receive signals. Signals travel along
the Soma or Cell Body and Summate at the Axon
Hillock The signal must be above a Threshold for
the signal to travel down the Axon
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Cell Structure From an Information Processing
View

• Dendrites
• Receive in Modulate signals Omnidirectionally
• They are graded potentials they decay as they
  travel
• Soma
• Where the signals are summed
• The amplitude and the timing (concurrence) are
  important
• The signal strength must be greater than the
  resistance at the axon hillock
• The threshold can shift
• The soma has a baseline
• Baseline indicates all is normal
• Indicates cell is alive
• Firing is not perfect, Noise can fire for no
  reason, or not fire when it should

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Cell Structure From an Information Processing
View

• Axons
• Transmit signals in one direction and are
  ballistic (all or nothing)
• Have myelin sheaths which sustain the signal
  strengths (do not decay)
• Their axon buttons or knobs release
  neurotransmitters

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Functional classification
Afferent or sensory neuron conduct impulses
from the sensory organs to the central nervous
system (brain and spinal cord) Efferent or
motor neuron conduct impulses from the central
nervous system to the effector organs (such as
muscles and glands) are called motor (or
efferent) neurons Interneurons (also known as
connector neurons or association neurons)
connect sensory neurons to motor neurons.
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Quizz

• The dendrite is part of the neuron which
• Is covered in myelin sheath
• Propagates signals in one direction only
• Receives modulated signals
• Releases neurotransmitters

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Functional classification

• The glial cells
• maintain the ionic environment
• modulate nerve signal propagation
• controls the uptake of neurotransmitters
• Protect by surrounding and buffering
• Speed transmission by forming myelin sheaths

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Quizz

• Glial cells have numerous functions. Which one of
  these is NOT one of its functions.
• To produce myelin sheathing
• Protect by surrounding and buffering
• Summing signals to trigger an action potentials
• A and C

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Signal Detection TheoryThink About This

• Each cell has a criteria for firing
• criteria shift
• No one neuron firing is sufficient information,
  the meaning is in the average rate in a given
  population.

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White Matter and Grey Matter
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• What is the Order of Intelligence? Why?

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Forebrain
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Function of Limbic System
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Hindbrain
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Lobes of the Cerebral Cortex
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• Frontal
• Reasoning Planning
• Parietal
• Touch, Temperature, Pain, Pressure
• Temporal
• Auditory Perceptual processing
• Occipital
• Visual processing

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The CortexThe Bark
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Prefrontal Cortex

• Recall the order of things
• Provides the brakes on impulse control
• Damage can produce Tourettes like symptoms of
  tic or exclaiming obscenities

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Story of Phineas Gage Damage to the Prefrontal
cortex

• Gage was fitful, irreverent, indulging at times
  in the grossest profanity (which was not
  previously his custom), manifesting but little
  deference for his fellows, impatient of restraint
  or advice when it conflicts with his desires, at
  times pertinaciously obstinate, yet capricious
  and vacillating, devising many plans of future
  operations, which are no sooner arranged than
  they are abandoned in turn for others appearing
  more feasible. A child in his intellectual
  capacity and manifestations, he has the animal
  passions of a strong man. Previous to his injury,
  although untrained in the schools, he possessed a
  well-balanced mind, and was looked upon by those
  who knew him as a shrewd, smart businessman, very
  energetic and persistent in executing all his
  plans of operation. In this regard his mind was
  radically changed, so decidedly that his friends
  and acquaintances said he was 'no longer Gage.

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Testing the Prefrontal cortex The Wisconsin Card
Sorting task

• The patient is told to sort the cards, but they
  are not told how to sort.
• But they are told if they matched the cards
  correctly.
• They must use their memory for the order of
  things to figure out the rules of the sorting.
• It took an entire manual to score the test,
  nowadays it is done on the computer.

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Primary Somatosensory and Motorsensory Cortex