Cognitive Neuroscience

-To identify the intellectual underpinnings and history of the concepts of cognitive neuroscience -To develop a working knowledge of the central nervous system and the basic functions which underlie human behavior -To understand the behavioral and neuroscientific methods that are applied to the study of cognition and brain function -To explain the major theories and models of fundamental cognitive processes and explore current thinking on how such models guide the study of the functioning human brain -*including perception, memory, attention, language, and emotion (basic higher cognitive functioning) -*uncover ingenious observation of clinical populations

WHAT IS COGNITIVE NEUROSCIENCE? Relatively new field of study that was only formally named in the late 1970s. • Combines the study of "Cognition" (process of knowing) and "Neuroscience" (study of the nervous system) • Goal: To understand how the functions of the physical brain are associated with mental processes and yield the output of the mind • Origins of modern cognitive neuroscience date back to the 1600s and earlier.

To understand how the functions of the physical brain are associated with mental processes and yield the output of the mind

• Origins of modern cognitive neuroscience date back to the 1600s and earlier.

• Combines the study of "Cognition" (process of knowing) and "Neuroscience" (study of the nervous system)

Relatively new field of study that was only formally named in the late 1970s.

A course you are taking to enrich your knowledge and restructure your brain! To further understand why it is so important to identify cognitive decline for neurosurgery and neurology

Aristotle (384-322 B.C.) - heart was seat of mind and soul • Galen (130-200 A.D.) - "spirits" flowed through ventricles of brain • Descartes (1630s) - pineal gland was seat of soul • Willis (1664) - beginning of modern view that the brain is responsible for mental functions

Cerebral cortex might be the center of what makes us human • Coined the term neurology (among others) • Compared behavior in life with brain structure at death • Compiled detailed drawings of brain anatomy with Christopher Wren

Period when modern approach to science (observation, manipulation, etc.) began to be applied to the study of the brain. Key question: • Does the brain work as a whole unit to enable mental processing? Or does the brain operate in a specialized fashion to enable the mind? • Willis' ideas were a launching pad for further work. Notably, neuroanatomist Franz Joseph Gall expanded Willis' ideas • Proposed that the brain was the origin of the mind and that our mental abilities could be localized in specific regions of the cortex.

• Does the brain work as a whole unit to enable mental processing? Or does the brain operate in a specialized fashion to enable the mind? • Both physiological and psychological approaches are necessary to achieve the scientific aims of cognitive neuroscience research.

Localizationist View: specific mental processes are localized in circumscribed brain areas. • Lead by Franz Joseph Gall (1758-1828) • Initial named "cranioscopy" or "anatomical personology" • Renamed "phrenology" by Johann Spurzheim

• Some disagreed with the localizationist views of Gall, et. al., • Lesioned brains in animals • Animals recovered function, regardless of the lesion site • Aggregate field theory • Brain is undifferentiated • Contrary to localization views • The whole brain participates in behavior

• Paul Broca (1824-1880) • Patient M. Leborgne aka "Tan" • Suffered a stroke • Aphasia: could comprehend speech but only say 'tan' • Lesion in the left inferior frontal lobe • Broca's area (Area B) • Carl Wernicke (1848-1905) • Stroke patient • Freely produces words • Incomprehensible • Also lack of comprehension • Wernicke's area • "A" -speech production • "Pc" -comprehension

• Korbinian Brodmann • German neuroanatomist • Used nissl stain • Identified cytoarchitechtonics: cellular architecture • Classified into 52 regions • "Brodmann Areas" • Still used in modern neuroscience today

Camillo Golgi (1843-1926) • Developed the famous silver stain to visualize entire individual neurons • He argued that the brain was a continuous mass of tissue that shared a common cytoplasm

• Santiago Ramon y Cajal (1852-1934) • Father of Modern Neuroscience • Used Golgi's stain to determine that neurons are distinct units • Argued for the neuron doctrine • Nervous system is made from discrete cells • Golgi and Cajal shared the Nobel prize in medicine in 1906

• Purkinje (1787-1869)

• During this time of early discovery about the neuron, localization views dominated • Localization views were eventually modified to acknowledge that individual parts of the brain may work in a cooperative and dependent fashion • These different approaches are still seen in science today. • Both are necessary for a full understanding of the brain and mind.

Scientists began to realize that the physiological research on neurons and brain structures (i.e., parts) need to be understood in the context of the whole (i.e., what they make when they come together: The Mind) • Early research on the mind and behavior comes out of philosophical approaches as well as experimental psychology.

Before experimental psychology, study of the mind was the domain of philosophers. A major line of thought at that time was: Associationism: the sum of a person's experiences determines the course of mental development. Closely tied to the school of psychological thought known as: Behaviorism: the idea that the environment and learning are the most important factors in development.

the idea that the environment and learning are the most important factors in development.

the sum of a person's experiences determines the course of mental development.

"Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in, and I'll guarantee to take any one at random and train him to become any type of specialist I might selecta doctor, lawyer, artist, merchantchief, and yes, even into a beggarman and thief, regardless of his talents, penchants, tendencies, abilities, vocations and race of his ancestors" • Pioneer of behaviorism

Originally a behaviorist • Gradually changed his view • "Psychology, the Science of Mental Life" • "The Magical Number Seven, Plus or Minus Two" • Brought concept of working memory to the forefront • Linguistic work • "Language and communication", 1951 • "The psychology of communication", 1967 • Collaborated with Noam Chomsky • Credited as the father of "cognitive neuroscience"

Focused on language • "father of modern linguistics" • Focused on language acquisition • Showed that associationism/ behaviorism could not explain how we acquire language: the pace of acquisition is too rapid for Skinner type mechanisms • Played a key role in the shift away from behaviorism

From the mid 1950s-1970s it became clear that the approaches of physiology, philosophy, neuropathology or experimental psychology alone could not explain all of learning and behavior. • George Miller and other scientists (including Gazzaniga) set out to understand how the brain and mind work as an integrated whole, with a unitary scientific approach, which eventually led to....

Development of imaging technologies CRITICAL to the progress of Cognitive Neuroscience • Electroencephalograph • Computerized Axial Tomography (CAT) • Positron Emission Tomography (PET) • Magnetic Resonance Imaging (MRI) • Functional Magnetic Resonance Imaging (fMRI)

• Cognitive Neuroscience is the integration of the study of the parts and the whole which enable the mind (the brain + cognition). • Empirical and evidence based field of study and theories are continually being revised and updated • Both physiological and psychological approaches are necessary to achieve the scientific aims of cognitive neuroscience research.

Ü Brain contains over 100 billion neurons Ü Octopus 300 million, a bee 950,000 Ü A single neuron may connect to as many as 200,000 cells Ü Typical 1,000 to 10,000 Ü Total of .15 quadrillion synapses Ü Length of giraffe primary afferent axon (toe to spine) is fifteen feet Ü Conduction velocity of the action potential is 1.2-250 mph

As long as our brain is a mystery, the universe, the reflection of the structure of the brain will also be a mystery - Ramon Cajal 1892

Neurons Ü Means of communication Ü Highways and bridges Ü Glia/ glial cells/ neuroglial cells Ü Greek for "glue" Ü support structure for the neurons Ü Cited as outnumbering neurons 10/1

Neurons: Transmit Information Glia: Supporting structures and damage repair 3 parts N Cell body/soma (1) metabolic Dendrites (X) rec info via synapses Axon (1) Sends info Information flows along neurons in only one direction Neurons all have same parts but can look very different and vary widely in size and shape

Schwann cells main type of glia In the PNS -- needed for insulation (faster information travel) and metabolic support (thinking is energy demanding) -- also help to regrow axons if peripheral nerve injury occurs In the CNS, more types of glial cells: -- Astrocytes -- Oligodendrocites -- Microglia 1. Maintain ionic balance of cells, 2. Transfer metabolites in and out of neurons, 3. Respond to neural injury by forming scar tissue Astrocytes

Ü Blood-brain-barrier Ü Tight endothelial cells line the capillaries Ü Blocks the passage of SOME molecules into the CSF Ü Astrocytes support endothelial cells Ü Transport ions across walls of blood vessels Ü Support/nutrition role Ü Regulate blood flow (tied to fMRI)

Ü Microglial cells serve as the brain's immune system Ü After injury they clear away dead and dying cells Ü They may also prune synapses between neurons

Ü Oligodendrocytes Ü Found in the Central Nervous System Ü Wraps itself around neurons to produce myelin Ü Mostly fat (80%) Ü Serves as an insulator Ü Can wrap around multiple neurons Ü Schwann Cells Ü Found in the peripheral nervous system Ü Also forms myelin Ü One cell wraps around only one neuron

Neuronal Communication Ü How to get a signal to the end of the axon terminal which can be far away from the cell body?

Specific properties of the cell structure and function enable transmission of information across the nervous system Key Concepts: Ü Resting Membrane Potential Ü Selective Permeability Ü Ion Exchange

Inside is more negatively charged relative to outside -70 mV is the average/typical polarization value but it is really a range (-40 to -90 mV -millivolts)

Transports 3 sodium ions from the inside of the cell to the outside - Transports two potassium ions into the cell - Requires energy from adenosine triphosphate (ATP) - ATP generated by the mitochonidria in cell body

Concentration Gradient Pressure to move from high concentration to a low concentration Think about the spread of dye in water Electrical Gradient Electrical charges repel Opposite electrical charges attract

- Allow the passage of ions across the membrane - Can be gated or non-gated - Channels have selective permeability to particular ions - Nongated K+ channels are the most common

passively move according to concentration gradient

Concentration gradient = electrochemical gradient - Equilibrium = -70 millivolts

To generate an action potential the membrane potential must reach the Threshold of Excitation (approximately -55mv). When Na+ channels open and the threshold is reached, depolarization occurs, propagating the signal down the axon.

All-or-None Principle Throughout depolarisation, the Na+ continues to rush inside until the action potential reaches its peak and the sodium gates close. If the depolarisation is not great enough to reach threshold, then an action potential is not produced. When the threshold is hit, a signal of equal strength to all other signals is sent. This is called the All-or-None Principle.

Impulses travel very rapidly along neurons. The presence of a myelin sheath greatly increases the velocity at which impulses are conducted along the axon of a neuron. In unmyelinated fibres, the entire axon membrane is exposed and impulse conduction is slower.

1. Action Potential propagates down axon to presynaptic terminals 2. Ca2+ causes vesicles to bind with cell membrane 3. Release of neurotransmitter by exocytosis into the synaptic cleft 4. Transmitter binds with receptor

Excitatory Postsynaptic Potential (EPSP) Excitation (or decrease in negativity) will further propagate additional Action Potentials Excitatory "synaptic potentials" sum for a cumulative effect. If the summation exceeds the threshold, AP will result.

Summation is critical. A single neuron may have multiple synaptic potential inputs.

NT are either synthesized in cell body (e.g., large molecule peptides) or in the synaptic terminals (e.g., smaller molecule NT). • Enzymes necessary for synthesis produced in cell body • Transported down the axon via slow or fast axonal transport molecules • small-molecule NT transported slowly (1 mm/day) to the terminal for synthesis • large-molecule peptides are synthesized in soma and transported quickly down the axon (400mm/ day) to the terminal

Remaining Neurotransmitter must be removed following its binding with postsynaptic membrane receptors. Completed with either: 1. Active Reuptake back into the presynaptic terminals 2. Enzyme-assisted breakdown of the NT in the synapse 3. By natural diffusion properties of the NT away from the site of action or Synapse Autoreceptors on the presynaptic membrane monitor the level of NT in the synapse, so they can accurately regulate how much synthesis and release are needed.

Some neurons communicate through electrical synapses Ü Two cells join at special locations called gap junctions Ü Linking two pools of water Ü Shared potentials Ü Current flows freely between them Ü Useful for fast transmission of information or synchrony Ü escape reflexes Ü retina