Cognitive Neuroscience: History and Medicine

Midterm Review: Cognitive Neuroscience - Spring 2025

Chapter 1: History

• Dualism posits that consciousness and the biological brain are separate, originating with Descartes.
• Monism suggests that consciousness and the biological brain are one entity.
• The "Simulation Theory" raises the question: "Are we living in a simulation?"
• The "Ship of Theseus" thought experiment questions whether an object remains the same if its parts are replaced over time.

Contributions of Medicine

• Thomas Willis linked brain damage to cognitive changes.
• Willis used anatomy through autopsy as a means to search for the soul
• Franz Joseph Gall advocated for phrenology, the localization of cognition, later discredited in the 1840s.
• Marie-Jean-Pierre Flourens opposed phrenology.
• Aggregate Field Theory suggests that the brain functions holistically for higher functions, rather than specific regions being responsible for particular tasks.
• Equipotentiality states if one part of the brain gets damaged, other parts will compensate.

Contributions of Medicine - Localization

• John Hughlings Jackson was an early proponent of localizationist perspectives.
• Paul Broca studied a stroke patient named "Tan" who could understand but not speak.
• Broca's Area is responsible for speech production.
• Carl Wernicke: Wernicke's area is a brain region associated with difficulty in comprehension but a capacity to produce fluent, nonsensical speech (gibberish).

Contributions of Medicine

• Camillo Golgi used silver nitrate stain to visualize entire neurons.
• Reticular Theory, championed by Camillo Golgi, incorrectly proposed the nervous system as a single continuous network.
• Santiago Ramón y Cajal correctly theorized through the Neuron Doctrine that the nervous system consists of discrete, individual cells.
• Korbinian Brodmann used Nissl Stain to stain cell bodies.
• Brodmann delineated 52 regions known as Brodmann Areas, offering descriptive but not necessarily functional labels.

Contributions of Psychology

• Wilhelm Wundt studied Introspection, which is cognition about self and looking inward
• William James concieved stream of consciousness which is consciousness as a river or stream
• James also used introspection

Contributions of Psychology - Behaviorism

• Behaviorism states, behavior is acquired through learning. Mental events are impossible to study.
• Humans are "blank slates" (tabula rasa).
• John Watson studied Classical Conditioning, which is the association of two stimuli.
• The Little Albert Study, conducted by John Watson, used classical conditioning to pair loud noises with a rat in a 9-month-old infant.
• B.F. Skinner studied Operant Conditioning which showed behavior is shaped and maintained by rewards and punishments.
• B.F. Skinner conducted the Pigeons in a Pelican experiment, which uses operant conditioning to train pigeons to guide missiles to correct targets.

Cognitive Revolution

• The cognitive revolution rejected behaviorism, and focused on studying mental processes.
• The revolution used the Scientific method to describe mental processes
• Ulric Neisser, Newell and Simon, Noam Chomsky, and George Miller supported the revolution

Chapter 2: Neurons & Neuroanatomy

Glial Cells

• Radial glial cells aid in the movement of new neurons to optimal spots
• Astrocytes maintain homeostasis, provide nutrition, and offer structural support in the central nervous system.
• Oligodendrocytes myelinate multiple cells
• Microglia function as the immune system of the brain.
• Schwann Cells myelinate a single cell in the peripheral nervous system.
• Satellite Cells offer protective support to neurons within ganglia in the peripheral nervous system.

Types of Neurons

• Unipolar neurons have a single branch and are usually found in invertebrates.
• Bipolar Neurons have on axon and one dendrite and ususally resides in sensory neurons (e.g., Retina)
• Pseudounipolar neurons begin as sensory neurons, but their axons and dendrites fuse.
• Multipolar neurons possess many branches, usually one axon and numerous dendrites; typical of neurons (e.g. pyramidal cells) in the brain.

Action Potential in the Neuron & Nervous Tissue

• Important elements include types of channels (non-gated, gated, voltage gated, ligand gated and G-coupled.)
• Resting potential is -70mV.
• Passive and active conduction are important to Action Potential in the Neuron & Nervous Tissue
• Refractory periods that are important (absolute vs. relative)
• Propagation in myelinated vs. unmyelinated axons.
• Myelin increases conduction speed through saltatory conduction.

Neuroanatomy

• The Central Nervous System includes the brain & spinal cord.
• The Peripheral Nervous System includes everything else.
• The PNS include both the Somatic division which is voluntary and the Autonomic division which is involuntary.
• The autonomic nervous system involves the sympathetic division "flight or flight" or the Parasympathetic: “rest and digest

Neuroanatomy directional terms

• Anterior (Rostral) goes Towards front
• Posterior (Caudal) goes Towards back
• Inferior (Ventral) goes Towards bottom
• Superior (Dorsal) goes Towards top
• Medial goes Towards midline
• Lateral goes Away from midline (side)
• Ipsilateral means on the same side
• Contralateral means on the opposite site
• Distal means far from a given point
• Proximal means close to a given point

Chapter 3: Methods

Methods in Cognitive Neuroscience

• ECOG employs electrode patches placed directly on the brain surface to measure neural activity.
• ECOG provides direct neural recordings, it is very invasive and requires surgery.
• Electroencephalogram (EEG) measures ongoing electrical activity on the scalp.
• EEG has real-time, direct neuronal measurements and is easy/cheap.
• EEG has poor localization and an "inverse problem.
• Event Related Potentials (ERP) are average EEG signals around stimuli
• ERP is Time-locked to specific sensory, cognitive, or motor events;can be difficult to interpret due to many influences on ERP components.

Other Measuring Methods

• Magnetoencephalography (MEG) detects neuronal interactions that lead to electrical voltage, electrical current and finally magnetic fields in a perpendicular direction.
• MEGs usage includes the analysis of magnetic fields and the use of SQuIDs
• MEG has good temporal & spatial resolution, direct neuronal measurements, used for surgical localization.
• MEG is expensive and sensitive to superficial structures.
• Transcranial Magnetic Stimulation (TMS) uses a magnetic field to induce current in the brain.
• Uses include excitation/inhibition of specific or virtual lesions, and clinical treatment.
• TMS is an ethical alternative to lesioning humans, with limitations in depth, duration, and accuracy.

Molecular Measuring Methods

• Positron Emission Tomography (PET) was founded by Edward Hoffman & Michael Phelps (WUSTL).
• PET employs radiolabeled tracers to assess metabolic activity by mapping blood flow/proteins, or neurotransmitter tracking.
• PET has decent spatial localization and maps specfic biological processes
• PET is expensive, has a slow time course, and involves radiation.
• Computed Tomography (CT) compiles multiple X-Ray images into a 3D structure to detect acute injuries, tumors, infections, and bone injuries.
• CT scans are cheap and quick.
• Due to Radiation and low resolution of soft tissue CT scans have limitations

Imaging Methods

• Magnetic Resonance Imaging (MRI) manipulates the orientation of hydrogen atoms for versatile strengths.
• MRI limitations include high cost and contradictions such as with metal implants.
• Diffusion Tensor Imaging (DTI) assesses white matter integrity by measuring water flow, distinguishing isotropic (no direction) from anisotropic (directional flow).
• Functional MRI (fMRI) measures brain activity via blood oxygenation level-dependent (BOLD) contrast to be used in perception, cognition, and memory tasks.
• fMRI has good spatial resolution with limitations in modest temporal resolution and indirect measurement of neuronal firing.
• Optical Imaging uses Near-infrared spectroscopy (NIRS) to assess oxygenated and deoxygenated hemoglobin in the brain, giving results similar to fMRI.
• Optical imaging is cheaper than fMRI and metal does not have the restraints
• Optical Imagining has Penetration depth limit (3-4cm.).

Miscellaneous Methods

• Arterial Spin Labeling (ASL) measures cerebral blood flow non-invasively.
• Nuclear Magnetic Resonance Spectroscopy (NMR) analyzes the molecular composition of tissues.
• Susceptibility-Weighted Imaging is sensitive to blood, iron, and calcium properties, and uses iron content as a proxy for microbleeds.
• Gadolinium Contrast T1 assesses the blood-brain barrier (BBB) permeability.

Chapter 4: Hemispheric Specialization

• Hemispheric lateralization is present, but has modest asymmetries.
• The Left hemisphere controls language
• The Right hemisphere controls some semantic information
• Several Theories suggest include speed for critical tasks, Specialization being more efficient and Nonidentical representations providing more information Organization is contralateral (opposite) organization, with focus on visual fields, not eyes.
• The Left visual field goes to the right hemisphere, while the right visual field goes to the left hemisphere

Corpus Callosum

• The role of the Corpus Callosum is primary mode of communication and integration
• There are three types of projections, including Ipsilateral: Same hemisphere, Contralateral: opposite hemisphere, Homotopic: side

Review of cognitive neuroscience history for the midterm, covering dualism, monism, Simulation Theory, and the Ship of Theseus. Includes the contributions of medicine, such as the work of Thomas Willis linking brain damage to cognitive changes and Franz Joseph Gall's phrenology. Also covers Aggregate Field Theory.