Cognitive Neuroscience Quiz

Cognitive Neuroscience

• Cognitive neuroscience is the scientific study of the relation between the nervous system and cognition.
• Neuroscience is the scientific study of the nervous system.

Building Blocks of the Nervous System

• Neurons are cells specialized to receive and transmit information in the nervous system.
• The brain is composed of approximately 100 billion neurons and over 100 trillion synapses (connections).
• Each neuron has a cell body, an axon, and dendrites.
• Cell body: Contains mechanisms to keep the cell alive.
• Axon: A tube filled with fluid that transmits electrical signals towards other neurons.
• Dendrites: Multiple branches reaching from the cell body to receive information from other neurons.

How Neurons Communicate

• Action potential (spike): Neurons receive signals from the environment.
• Measuring action potentials: The size (amplitude) of the action potential remains mostly constant, but the rate of firing is measured. Low intensity input corresponds to slow firing, and high intensity input corresponds to fast firing.
• Synapse: Space between the axon of one neuron and a dendrite of another neuron.
• Neurotransmitters: Chemicals that affect the electrical signal of the post-synaptic neuron.
  • Excitatory neurotransmitters increase the likelihood of the post-synaptic neuron producing a spike (e.g., glutamate).
  • Inhibitory neurotransmitters decrease the likelihood of the post-synaptic neuron producing a spike (e.g., GABA).
  • Some neurotransmitters can be both excitatory and inhibitory, depending on context (e.g., dopamine).
• How neurons process information: Not all signals received by a neuron lead to an action potential. The cell membrane processes the number and timing of impulses received. An action potential results only if the threshold level is reached. This involves interactions of excitation and inhibition.

Representation in the Brain

• Feature detectors: Neurons that respond best to a specific stimulus.
  • Simple cells: Neurons respond best to bars of light with a particular orientation.
  • Complex cells: Neurons respond best to oriented bars of light with a specific length.
• Specificity coding: A specific stimulus is represented by the firing of specifically tuned neurons that only respond to that specific stimulus.
• Distributed coding: A specific stimulus is represented by a pattern of firing across a large number of neurons.
• Sparse coding: A distributed representation that uses a small number of neurons.

Localization of Function

• Specific functions are served by specific areas of the brain.
• Cognitive functioning breaks down in ways that are related to the particular area of brain that is damaged.
• Cerebral cortex (3-mm thick layer covering the brain): Contains mechanisms responsible for many cognitive functions.
• Subcortical areas (e.g., basal ganglia): Also have important cognitive function.
• Lobes of the Cerebral Cortex: The four lobes of the brain, responsible for particular functions
  • Frontal: Reasoning, planning, language, thought, memory, motor functioning.
  • Parietal: Visual attention, touch, temperature, pain, pressure.
  • Temporal: Auditory and perceptual processing, language, hearing, memory, perceiving forms.
  • Occipital: Visual processing.
• Subcortical Structures: These structures are important to cognitive function and typically lie beneath the cerebral cortex. Some key examples include:
  • Basal ganglia: Involved in categorization and sequence processing.
  • Hippocampus: Involved in forming memories.
  • Amygdala: Involved in processing emotions and emotional memories.
  • Thalamus: Involved in relaying sensory information from vision, hearing, and touch.

Methods of Study

• Lesions: Used in both non-human animals (lesions can be experimentally created) and patients (e.g., neurological events). Lesions in humans need to be accidental and are rarely focal. (E.g., a stroke)
• TMS (Transcranial Magnetic Stimulation): Safely reproduces the effect of a temporary cortical lesion or temporarily adds noise to neural activation. This can be used to study whether a particular brain location was involved in specific mental tasks.
• Inactivation using techniques like muscimol: For studying the functions of neural structures other than those in the cortex. Muscimol is a GABA agonist.
• Brain Imaging: Techniques allowing researchers to view brain activity during task completion
  • PET (Positron Emission Tomography) measures blood flow.
  • fMRI (Functional Magnetic Resonance Imaging): Measures blood flow through magnetic properties of blood. No radioactive tracer needed.
  • EEG (Electroencephalography): Measures electrical activity on the scalp to make inferences about underlying brain activity. ERP (event-related potential).

Additional Topics

• Distributed processing: Cognitive functions often involve numerous brain areas that work together.
• Do brains make us lose our minds?: Neuroscientific explanations of psychological phenomena can be misleading. Adding neuroscience factoids to poor explanations can add to that misleading quality, especially for those unfamiliar with the field.
• Difficulty with inferring what others know: People often struggle to accurately predict what others know and may project their own knowledge onto the others.