Psy315 - Classes 3 and 4: Neuroscience

(This page last updated 14 August, 2006.)

Phineas Gage

• Iron rod through frontal lobes.
• Dramatic change in personality.
  • Before the accident, he was a capable foreman, and considered a smart businessman.
  • After his recovery, he was "fitful, irreverent, and grossly profane, showing little deference for his fellows."
  • "…impatient and obstinate, yet capricious and vacillating, unable to settle on any of the plans he devised for future action."
  • " No longer Gage", according to his friends.
• How could brain damage change personality?

Methods for Studying the Brain and its Function

• Single Cell Recording
  • Electrode through skull and into brain.
  • Records differences in electrical potential over time in a single neuron or small group of neurons.
  • Action potentials
    • All-or-none firing
    • Firing rate varies depending on strength of input.
  • Excellent temporal and spatial resolution
• Electroencephalogram (EEG)
  • Electrodes placed on scalp.
  • Each electrode measures changes in electrical potential at its location.
  • Measurement from each electrode reflects activity from large numbers of neurons.
  • Neurons near brain surface produce stronger signals than those deep in the brain.
  • Signals can be combined to produce maps of activation across brain surface.
  • Temporal resolution excellent. Spatial resolution not as good.
• X-Ray Computed Tomography (CT or CAT)
  • Multiple X-ray images
  • Combined computationally
  • Produces images of slices through brain (or other parts of body).
  • Very useful for localizing damage.
  • Shows only structure, not function.
• Positron Emission Tomography (PET)
  • Radioactive substance introduced to bloodstream
    • Injected
    • Inhaled
  • Ring of detectors around head record positrons from radioactive decay
  • Active areas of brain receive more blood, and thus produce more positrons.
  • Can computationally produce images of brain slices.
  • Different colors show different levels of blood flow and thus different levels of brain activity.
  • Shows function, but not structure.
  • OK spatial resolution. Poor temporal resolution.
• Nuclear Magnetic Resonance Imaging (MRI)
  • Giant magnet creates strong magnetic field.
  • Molecules align to magnetic field.
  • Sudden radio pulse knocks them out of alignment.
  • Different types of molecules produce different responses.
  • Can produce maps showing concentrations of different substances
  • Shows structure, not function.
• Functional Magnetic Resonance Imaging (fMRI)
  • Use MRI to measure blood flow (and therefore activity) in brain.
  • Shows brain function.
  • Colors representing different levels of activity can be added to structural images of brain slices or brain surface.
  • Both spatial and temporal resolution improving.
• Transcranial Magnetic Stimulation (TMS)
  • Produces brief magnetic pulse.
  • Can interfere with brain activity within small region near surface.
  • TMS in motor areas can produce sudden movement.

Brain Organization 

Hindbrain

• Connected to spinal cord.
• Heart rhythm, breathing
• Posture and balance
• Alertness, sleep, dreaming

  Cerebellum

  • Coordinating movements
  • Learning of motor skills

Midbrain

• Coordinating movements
• Eye movements
• Relaying auditory information

Forebrain

Hypothalamus

• Regulates motivation
  • Eating
  • Drinking
  • Reproduction

Limbic System

• A variety of structures
  • Hippocampus
  • Mammillary bodies
  • Amygdala
• Learning and memory
• Emotion

Thalamus

• Relays sensory information to cortex

Cortex

• Also called cerebral cortex or cerebrum
• Very large in humans

  Two separate hemispheres, each organized into four lobes.

  Occipital Lobe

  • Early visual processing

  Temporal Lobe

  • Object recognition
  • Early auditory processing
  • Long Term Memory

  Parietal Lobe

  • Spatial location
  • Manipulating objects
  • Sense of touch

  Frontal Lobe

  • Planning
  • Working memory
  • Motor control

  Sensory and Motor Areas

  • Primary Motor Area - in frontal lobe, near parietal boundary
    
  • Primvary Visual Area - in occipital lobe
    
  • Primary Auditory Area - on upper part of temporal lobe
    
  • Primary Somatosensory Area - in parietal lobe, near frontal boundary

next class: Visual System

Neuroscience Web sites you may find interesting:

• Brain Explorer
• The Whole Brain Atlas
• The Brain Museum
• Neurosciences Internet Resource Guide
• BrainInfo
• Dana Index of Brain Disorders
• Information on Phineas Gage
• PBS: The Secret Life of the Brain

Psych 315: Cognitive Psychology Kyle Cave Psychology Dept. U. Mass.