Early Theories of Brain Function

Early Theories of Brain Function

• Aristotle believed the heart was the center of the mind.
• Galen believed the brain was the center of the mind.
• Willis linked brain areas to functions (incorrectly).
• Gall's phrenology was pseudoscience.
• Localization of function: different areas of the brain do different things.
• Distributed processing: the brain works together.
• Flourens' ablation experiments showed the importance of cerebral hemispheres.
• Broca and Wernicke linked specific brain areas to speech function.
• Cajal's neuron doctrine described the nervous system as made up of individual nerve cells (neurons).

Understanding Brain Activity

• Three problems about the existence of the mind are: the possibility of creating new rule-based sentences, the possibility of studying mental processes with mri and other similar technologies and the fact humans can study themselves via introspection.
• Cognitive Psychology view: perception, attention, memory, language and thinking.
• Dendrites receive messages from other neurons.
• Nodes of Ranvier are short regions of axon membrane without myelin.
• Ion channels move ions across axon membranes.
• An action potential causes local changes in ion concentration that travels down the axon to send messages.
• Neurons aren't physically connected; they communicate via neurotransmitters across a synapse.
• The synaptic cleft is the gap between neurons.
• A neurotransmitter is a chemical messenger.
• Synapses are junctions between neurons where neurotransmitters are released.
• Presynaptic cells transmit signals, postsynaptic cells receive signals.
• Steps of neurotransmission: action potential, neurotransmitter release, neurotransmitter binding to receptors, ion flow, postsynaptic potential, excitatory/inhibitory potential.
• Resting membrane potential is the voltage difference across the membrane at rest.
• Hyperpolarizing response makes the membrane more negative.
• Depolarizing response makes the membrane more positive.
• Threshold potential triggers action potential.
• Refractory period prevents immediate re-excitation
• All-or-nothing principle: A neuron either fires or it doesn't resulting from a specific chemical process.
• Directionality terms: anterior/ventral, posterior/dorsal, superior, inferior, medial, lateral, rostral, caudal
• Planes of section: coronal, sagittal, horizontal

Brain Structures

• Surface anatomy: gyri (ridges), sulci (grooves), fissures (deep sulci).
• Grey matter: cell bodies, dendrites, synapses.
• White matter: myelinated axons.
• Structures: cerebellum (motor skills), brain stem, cerebrum (cognitive functions).
• Four lobes of cerebral cortex: frontal, parietal, temporal, occipital.
• Frontal lobe: reasoning, social behaviour, language production.
• Parietal lobe: spatial awareness, navigation, perception.
• Temporal lobe: auditory processing, high-level visual processing, language comprehension.
• Occipital lobe: visual processing.
• Association cortex: integrates information across sensory modalities.

Recording and Studying Brain Activity

• Localization of function is tested by studying the affect of brain lesions on cognitive abilities.
• Contralateralization is opposed to ipsilateral signaling, with different body regions in the brain being controlled by different parts of the body on the opposite side.
• Different parts of the brain have different topographic organization.
• The nervous system shows topographic organization and contralateralization.
• Spatial organization in the body regions in the brain are connected proportionally to their sensitivity.
• Thalamus relays sensory information.
• Basal ganglia is involved in movement, conditioning, emotion.
• Hippocampus relates to memory and spatial awareness.
• Amygdala handles emotional response and regulation.
• EEG (electroencephalography): measures electrical activity; poor spatial, good temporal resolution.
• ERP (event-related potentials): averages EEG data to isolate responses to specific events; decent spatial, good temporal.
• MEG (magnetoencephalography): measures magnetic fields; decent spatial, good temporal.
• fMRI (functional magnetic resonance imaging): measures blood flow; excellent spatial, poor temporal.
• TMS (transcranial magnetic stimulation): non-invasive way to stimulate or suppress brain activity; high spatial and temporal.
• Lesion studies and methods of studying brain damage.
• Single dissociation and double dissociation.
• Plasticity in some brain regions allows compensation for lesions.

Explore the foundational theories regarding brain function, from Aristotle's belief in the heart to modern understandings of brain localization and distributed processing. This quiz covers pivotal figures and concepts in neuroscience, including phrenology, neuron doctrine, and the contributions of Broca and Wernicke. Test your knowledge on the evolution of our understanding of the mind and brain activities.