Chapter 2 - Exam 1 - PBSI 345

Cognitive neuroscience

- The study of the physiological basis of cognition

- Involves an understanding of both:

• the nervous system

• individual units that comprise that system

Ramon y Cajal

- Neuron Doctrine

- investigated the nerve net

- Individual nerve cells transmit signals, and are not continuously linked with other cells

Camillo Golgi

developed a staining technique in which a thin slice of brain tissue was immersed in a solution of silver nitrate

- fewer than 1 percent of the cells were stained, so they stood out from the rest of the tissue. (If all the cells had been stained, it would be difficult to distinguish one cell from another because the cells are so tightly packed.)

- the cells that were stained were stained completely, so it was possible to see their structure.

Hubel & Wiesel

- research with visual stimuli in cats

- hey called these neurons feature detectors because they responded to specific stimulus features such as orientation, movement, and length.

Blackmore and Cooper

- Cats are born with the ability to perceive both horizontal and vertical lines but without certain experiences, they miss out on development of these skills

- an early demonstration of experience-dependent plasticity.

Nancy Kanwisher

Co-discovery of the Fusiform Face Area (FFA)

- Essential for understanding the representation of faces and environmental scenes in the brain

Panzeri and Colleagues

Population Coding

level of analysis

topics can be studied in variety of ways, at different levels or dimensions

Neurons

cells specialized to create, receive, and transmit information in the nervous system

- Each neuron has a

• cell body

• an axon

• dendrites

cell body

contains mechanisms to keep cell alive

Dendrites

multiple branches reaching from the cell body, which receive information from other neurons

Axon

tube filled with fluid that transmits electrical signal to other neurons

Neural Circuits

Group of interconnected neurons that are responsible for neural processing.

- Cajal's idea of individual neurons that communicate with other neurons to form neural circuits was an enormous leap forward in the understanding of how the nervous system operates.

Nerve net theory

Early concept of interconnected neurons creating a nerve net, similar to a highway network

- Streets are connected without stop signs

- This allows for almost nonstop, continuous communication of signals throughout the network

- Contradicted by the neuron doctrine

Neuron Doctrine

The idea that individual cells called neurons transmit signals in the nervous system, and that these cells are not continuous with other cells as proposed by nerve net theory.

Golgi stain

- used to view/visualize nervous system cells

Resting potential & charge

Difference in charge between the inside and outside of a nerve fiber when the fiber is at rest (no other electrical signals are present).

- the inside of the neuron has a charge that is 70 mV more negative than the outside, and this difference continues as long as the neuron is resting.

Threshold

the smallest signal strength that can barely be detected

Depolarization/Repolarization cycle

these steps create the action potential cycle, which is essential for transmitting signals in nerves and triggering contraction in muscles.

spike

Each action potential is referred to as a spike

Receptors

Specialized neural structures that respond to environmental stimuli such as light, mechanical stimulation, or chemical stimuli.

Principle of Neural Representation

Everything a person experiences is based on representations in the person's nervous system.

Feature Detectors

Neurons that respond to specific visual features, such as orientation, size, or the more complex features that make up environmental stimuli.

​Experience-Dependent Plasticity

A mechanism that causes an organism's neurons to develop so they respond best to the type of stimulation to which the organism has been exposed.

Vertical-only kittens study & who developed it

- Kittens raised in an environment with only vertical contours developed a visual cortex that responded almost exclusively to vertical features. As a result, they reacted to vertical objects but ignored horizontal ones, since neurons tuned to horizontal contours never developed.- Colin Blakemore and Graham Cooper

​Hierarchical Processing

Processing that occurs in a progression from lower to higher areas of the brain.

sensory coding

How neural firing represents various characteristics of the environment.

specificity coding

representation of a stimulus by the firing of specifically tuned neurons specialized to respond only to a specific stimulus

population coding

representation of a stimulus by the pattern of firing of a large number of neurons

sparse coding

representation of a stimulus by a pattern of firing of only a small group of neurons, with the majority of neurons remaining silent

​What are each of the lobe's functions?

Occipital - analyzing incoming visual information

Parietal - ensations caused by stimulation of the skin and also some aspects of visual information

Temporal -

Frontal - higher functions such as language, thought, memory, and motor functioning

Broca's area

An area in the frontal lobe associated with the production of language. Damage to this area causes Broca's aphasia.

Wernicke's area

Area in the temporal lobe associated with understanding language. Damage to this area causes Wernicke's aphasia.

Double Dissociation: definition & importance

A situation in which a single dissociation can be demonstrated in one person and the opposite type of single dissociation can be demonstrated in another person (i.e., Person 1: function A is present, function B is damaged; Person 2: function A is damaged, function B is present).

- Enables us to conclude that functions A and B are served by different mechanisms, which operate independently of one another.

Broca's aphasia

A condition associated with damage to Broca's area, in the frontal lobe, characterized by labored ungrammatical speech and difficulty in understanding some types of sentences.

Wernicke's aphasia

A condition, caused by damage to Wernicke's area, that is characterized by difficulty in understanding language, and fluent, grammatically correct, but incoherent speech.

Fusiform Face Area (FFA)

An area in the temporal lobe that contains many neurons that respond selectively to faces.

Parahippocampal Place Area (PPA)

An area in the temporal lobe that contains neurons that are selectively activated by pictures of indoor and outdoor scenes.

Extrastriate Body Area (EBA)

An area in the temporal cortex that is activated by pictures of bodies and parts of bodies, but not by faces or other objects.

localization of function

Location of specific functions in specific areas of the brain. For example, areas have been identified that are specialized to process information involved in the perception of movement, form, speech, and different aspects of memory.

multidimensional

The multidimensional nature of cognition refers to the fact that even simple experiences involve combinations of different qualities.

Neural Networks

Groups of neurons or structures that are connected together.

Define Connectome and track-weighted imaging

- connectome: A map of the brain that details the complex network of neurons and their connections.

- TWI: A technique for determining connectivity in the brain that is based on detection of how water diffuses along the length of nerve fibers.

Functional Connectivity

The extent to which the neural activity in separate brain areas is correlated with each other.

Resting-State fMRI Networks

The fMRI response recorded when a person is at rest (not involved in any cognitive tasks).

​Default Mode Network (DMN)

Network of structures that are active when a person is not involved in specific tasks.

What brain regions are involved DMN?

medial prefrontal cortex, posterior cingulate cortex/precuneus, hippocampus, inferior parietal lobule, and lateral temporal cortex. These regions work together when the brain is at rest, supporting processes like memory, imagination, self-reflection, and internal thought.