Unit 2: Brain and Cognition

Unit 2: Brain and Cognition

• The brain is responsible for cognitive abilities, such as mathematical ability, language skills, and memory.
• Different brain areas are connected by specific white matter fibers, such as the cingulum fibers for mathematical ability and arcuate fasciculus for language skills for example.
• Another example is the fornix fibers in relation to memory.

Questions to Consider

• Cognitive neuroscience is the study of the physiological basis of cognition and allows us to explore how information is transmitted in the nervous system, how the environment is represented, and whether minds can be read by measuring brain activity.
• The nervous system transmits information from one place to another, resulting in various cognitive processes.
• The environment is represented in the brain by specialized areas dedicated to processing specific information, such as faces and trees.
• Whether or not the human mind can be read by measuring brain activity is still an open question.

Very Simply...

• Understanding the basic principles of nervous system function and the methods used to study the physiology of cognition are key elements.
• The physiology of cognition is studied using specific methods.

Let's Start with an Example

• The provided example in figure 2.1 (page 25) illustrates the process of receiving and interpreting sound waves, in the context of a waking person who hits the snooze option, and how this process relates to neural activity, specifically noting the transmission of signals from sensory areas to motor areas in the brain.

Overview

• Chapter 2 provides foundational knowledge on neurophysiology and neuroscience to improve cognitive understanding via physiological factors.
• It also presents methods used to study brain physiology.

The Mind's Computer

• The mind is what the brain does, but its exact relationship to the brain is still a subject of discussion and debate, particularly in relation to the mind-body problem.
• Philosophical questions about the relationship between the mind and the brain have existed for centuries.

Brain Layout : The Cortex

• The cerebral cortex, the outer layer of the brain, is divided into specific lobes.
• Examples of lobes are temporal, occipital parietial, and frontal lobes.
• Two brain hemispheres and the corpus callosum are critical for interhemispheric communication and contralateral function.

Brain Layout : The Subcortex

• The subcortex contains structures not directly related to the highest level thoughts, such as the thalamus, amygdala, and hippocampus.

Neurons: Building Blocks of the Nervous System

• Neurons are responsible for information transmission and processing.
• Glial cells are an essential part of the nervous system, but neurons are the components responsible for the transfer of information.
• Neurons run throughout the body and are connected with the sensory systems (vision, hearing, taste, touch).

Key Neuronal Components (Slide 11)

• The parts of a neuron include cell body, dendrites, axon, and axon hillock.
• These components play a role in transmitting signals throughout the nervous system.

Basic Components of a Neuron (Page 12)

• Neurons receive information from environmental stimuli (in the case of the example, tactile pressure) via specialized receptor (the component)
• Information transmission occurs through electrical (impulses).
• Transfer of signals occur at synapses.

Building Blocks of the Nervous System (Page 13)

• Neurons are the fundamental cells of the nervous system, responsible for receiving and transmitting information.
• Each neuron consists of a cell body, axon, and dendrites

Building Blocks of the Nervous System (Page 14)

• The cell body contains essential mechanisms for maintaining its functionality and survival.
• The axon transmits electrical signals.

Building Blocks of the Nervous System (Page 15)

• Dendrites receive information from other neurons at synapses and transmits signals to the neuron's cell body.
• Sensory receptors receive information from the senses.

Many Types of Neurons (Page 16)

• Different types of neurons exist with various shapes and functionalities depending on their placement in the nervous system.
• The different shapes and functions of neurons illustrate the intricate design of the nervous system.

Receptors and Information Transmission (Page 17)

• The question is raised about how specialized receptors convert environmental information into a usable format for neurons and the brain.

How Neurons Communicate (Page 18)

• Action potential is a neural signal transmission.
• Information transmits down the axon to the dendrites of another neuron.

How Neurons Communicate (Page 19)

• Action potentials are measured electrically using microelectrodes to gauge the electrical activity.
• Microelectrodes are placed near an axon to measure an action potential in response to a stimulus.
• Active action potentials are measured over a period of about one second.

Measuring Action Potentials (Page 20)

• Action potentials are brief changes in membrane potential that convey signals along the axon of a neuron.
• The size of the action potential remains constant, but the rate of firing varies depending on the intensity of the stimulus.
• A "spike" is a single action potential.

How Neurons Communicate (Page 21)

• The rate of firing, not the size, of action potentials, indicates the intensity of a stimulus.
• Low intensities produce slow firing rates, while high intensities produce fast firing rates.

How Neurons Communicate (Page 22)

• Examples are provided, illustrating that an increase in light intensity leads to an increased firing rate.

How Neurons Communicate (Page 23)

• Synapses are the gaps between neurons where chemical neurotransmitters are released to facilitate communication between neurons.

How Neurons Communicate (Page 24)

• Neurotransmitters are chemicals that affect the receiving neuron and can be excitatory or inhibitory.
• Excitatory neurotransmitters increase the neuron's firing rate; inhibitory neurotransmitters decrease it.

How Neurons Process Information (Page 25)

• An action potential will only occur if the required threshold level is met from the processing of the number of stimuli, through an interaction of excitation and inhibition.

Quick Summary of How a Neuron Works (Page 26)

• Neurons receive stimuli from other neurons or receptors.
• Stimuli travel from dendrites to the axon hillock and generate electrical signals along the axon.

Important Neural Properties (Page 27)

• Propagation: Electrical signals travel down the axon without degradation or signal weakening.
• Rate of Action Potentials: Neuron firing rates (not spike heights) indicate the intensity of stimuli.

Neural Communication (Page 28)

• Synapse: The space between the axon terminal of one neuron and the dendrite of another neuron.
• Neurotransmitters: Chemical messengers that cross the synapse to excite or inhibit the receiving neuron.

Localization of Function (Page 29)

• Specific brain areas are responsible for specific functions.
• Damage to specific areas can disrupt those functions in specific ways.
• The cerebral cortex is crucial for most cognitive functions.

Lobes of the Cerebral Cortex (Page 30)

• Different lobes in the cortex have specific functionalities.
• The Frontal lobe is responsible for reasoning, planning, and higher cognitive functions involving appropriate social behavior and emotions.
• The Parietal lobe, responsible for processing sensory information such as touch, temperature, pain, and pressure.
• The Temporal lobe, involved in auditory processing, language comprehension, memory, recognizing forms, and perceptual processing.
• The Occipital lobe, responsible for visual processing.

Localization of Function: Limbic System (Page 32)

• The limbic system includes the hippocampus (memory), amygdala (emotions and emotional memories), and thalamus (sensory processing).
• Different brain areas are responsible for different types of processing/functions, and these areas interact closely with one another.

Localization of Function: Perception (Page 34)

• Primary areas in the brain detect sensory input such as vision, and touch
• Perception involves the processing and interpretation of sensory information.
• The frontal lobe plays a role in coordinating information received from multiple senses.

Localization of Function: Perception (Page 35)

• Specific brain areas, such as the fusiform face area (FFA), parahippocampal place area (PPA), or extrastriate body area (EBA), respond selectively to stimuli and facial recognition is an example of selectivity.
• Specialized brain areas, such as the temporal lobe for instance, respond to faces, places, and bodies.
• Damage to the facial recognition area can result in prosopagnosia.

Localization of Function: Language (Page 37)

• Language production is impaired due to damage to Broca's area (frontal lobe).
• Language comprehension is affected by damage to Wernicke's area (temporal lobe).

Examples of speech and damage to Wernicke's or Broca's areas (Page 38)

• Examples of speech impairments are provided as cases of broken speech in relation to damage to specialized areas for language, such as Broca's and Wernicke's areas, specifically.

Distributed Processing in the Brain(Page 40)

• Specific functions are processed by multiple brain regions, in addition to localization of the function alone.
• Multiple areas are involved in many functions.

Method: Brain Imaging (Page 42)

• Positron Emission Tomography (PET): Measures brain activity by detecting blood flow increases in response to cognitive tasks with the use of a radioactive tracer within the bloodstream.
• Higher signals indicate higher brain activity.

Method: Brain Imaging (Page 44)

• Subtraction technique: Measuring brain activity differences before and during stimulation, to determine active brain areas during manipulation and function.

Method: Brain Imaging (Page 46)

• Functional Magnetic Resonance Imaging (fMRI): Measures blood flow changes in response to brain activity using magnetic properties through a subtraction technique without needing radioactive tracer.

Method: Event-Related Potential (ERP) (Page 47)

• Event Related Potential (ERP): Measures electrical activity on the scalp to understand underlying brain activity through electrical inferences where an electrical event (in this instance a neuron firing) is measured over many trials.
• Continuous and rapid measurements are conducted but precise location information is not available through this method.

Representation in the Brain (Page 49)

• Feature detectors, neurons that respond to specific stimuli effectively, particularly as discovered by Hubel and Wiesel (1965).
• Simple cells respond to light bars; complex cells recognize light bars with specific orientations and lengths which are important neurons in the visual cortex.

Representation in the Brain (Page 51)

• Specificity coding: A neuron is specialized in response to a certain stimuli.
• Distributed coding: Patterns, across groups of neurons, represent a stimulus.

Explore the intricate relationship between the brain and cognitive abilities in this quiz. Delve into how different brain areas are connected and how they facilitate skills such as language, memory, and mathematical ability. Understand the principles of cognitive neuroscience and the transmission of information in the nervous system.