PSC 100 - Lecture 3 - Neural Basis of Cognition

brain

This organ is only 3 lbs but is the most complicated object known to science

100-200 billion, 100 trillion

The Brain

How many neurons does the brain have? How many connections?

dendrites

Neurons & Glia

Basic Parts of a Neuron

Detects incoming signals from other neurons

cell body

Neurons & Glia

Basic Parts of a Neuron

Contains the nucleus and cellular machinery

axon

Neurons & Glia

Basic Parts of a Neuron

Transmits signals to other neurons

releases neurotransmitters

Neurons & Glia

The Synapse

What happens when an electrical signal from the cell body (AP) reaches the axon terminals?

act on the membrane of the postsynaptic neuron

Neurons & Glia

Basic Parts of a Neuron

What do neurotransmitters do?

trigger the flow of ions

Neurons & Glia

Basic Parts of a Neuron

What happens when neurotransmitters act on the membrane of the postsynaptic neuron?

When there’s sufficient ionic flow to pass the cell’s threshold

Neurons & Glia

Basic Parts of a Neuron

How is an action potential produced?

all or nothing law

Neurons & Glia

Basic Parts of a Neuron

Describes how an AP is always of the same magnitude; signal frequency can differ depending on stimulus

in one direction

Neurons & Glia

Basic Parts of a Neuron

How do AP’s travel down the axon?

myelination

Neurons & Glia

Basic Parts of a Neuron

Blank of axons make spike propagation vv fast but not instantaneous

reaction time

Neurons & Glia

Basic Parts of a Neuron

This physiological response slows with aging; more neurons need to be activated

synaptic transmission, dendrites, cell body

Neurons & Glia

Basic Parts of a Neuron

Blank allows a neuron to receive (at blank), and integrate (at blank) information from many other neurons

compare them and adjust responses to input

Neurons & Glia

Basic Parts of a Neuron

Synaptic Transmission

What can neurons do with incoming signals?

neural plasticity

Neurons & Glia

Basic Parts of a Neuron

Synaptic Transmission

Describes how the strengths of synaptic connections are adjustable

• Altered by experience, development, aging, pathology

• Crucial for learning

• Can also be altered pharmacologically

glia

Neurons & Glia

Functions include…

• Guiding development of nervous system (like scaffolding)

• Repairing damage in the nervous system

• Controlling nutrient flow to neurons

• Electrical insulation

hindbrain

Hindbrain, Midbrain, & Forebrain

Top of the spinal cord; key life functions

• Contains the cerebellum & brainstem

cerebellum

Hindbrain, Midbrain, & Forebrain

Largest region of the hindbrain that is involved in movement, coordination, & balance

brainstem

Hindbrain, Midbrain, & Forebrain

Responsible for key life functions; medulla & pons

midbrain

Hindbrain, Midbrain, & Forebrain

Responsible for coordinating precise eye movement, relaying auditory info from ears to forebrain & regulating pain experiences

forebrain

Hindbrain, Midbrain, & Forebrain

Surrounds the midbrain and most of the hindbrain; includes the cortex, four lobes, & subcortical structures

cortex

Hindbrain, Midbrain, & Forebrain

The outer surface of the forebrain; approx 80% of the brain

• Divided into 2 cerebral hemispheres by the longitudinal fissure

thalamus

Hindbrain, Midbrain, & Forebrain

Subcortical Structures

Relays sensory info

hypothalamus

Hindbrain, Midbrain, & Forebrain

Subcortical Structures

Controls behaviors that serve specific biological needs (e.g. eating)

amygdala

Hindbrain, Midbrain, & Forebrain

Subcortical Structures

Part of the limbic system that’s responsible for emotional processing

hippocampus

Hindbrain, Midbrain, & Forebrain

Subcortical Structures

Part of the limbic system responsible for learning & memory

lateralization, contralateral cortical organization

Hindbrain, Midbrain, & Forebrain

Literally sidedness, referring to the specialization in certain functions by each side of the brain, w/one side dominant for each activity (left brain controls right & vice versa, aka blank)

commissures, corpus callosum

Hindbrain, Midbrain, & Forebrain

Lateralization

The two hemispheres of the brain are connected by blank, which are thick bundles of fibers that carry information

• What is the largest one?

hemispheric specializations of functions

Hindbrain, Midbrain, & Forebrain

Lateralization

What evidence did studies on split brain patients reveal?

neuropsychology

Sources of Evidence About the Brain

The study of the brain’s structures and their relation to function

• Includes clinical & lesions

• Who is the most famous example?

CAT scan

Sources of Evidence About the Brain

Data from Neuroimaging

A structural neuroimaging technique that is fast, inexpensive, maps out tissue density, and bone structure

MRI

Sources of Evidence About the Brain

Data from Neuroimaging

A structural neuroimaging technique that is great for looking at finer detail, and allows researchers to see the structure of the brain (but not activity)

PET

Sources of Evidence About the Brain

Data from Neuroimaging

A functional neuroimaging technique that uses radioactive substances to trace brain activity (incl. O2)

fMRI

Sources of Evidence About the Brain

Data from Neuroimaging

A functional neuroimaging technique that traces the flow of oxygenated blood WITHOUT the use of radioactive substances; detects small changes in brain metabolism & can show how various networks of brain structures respond to various stimuli

• Strength: Spatially locating neural activity (where)

• Weakness: Temporally locating neural activity (when)

fusiform face area

Sources of Evidence About the Brain

Data from Neuroimaging

The blank gets activated when you perceive a face

parahippocampal place area

Sources of Evidence About the Brain

Data from Neuroimaging

The blank gets activated when you perceive a place

chemical

Sources of Evidence About the Brain

Data from Electrical Recordings

Communication between neurons is…

electrical

Sources of Evidence About the Brain

Data from Electrical Recordings

Communication within a neuron is…

EEG

Sources of Evidence About the Brain

Data from Electrical Recordings

Recording of the electrical communication within neurons

• Used to study broad rhythms (e.g. sleep stages)

• Strength: Temporally locating neural activity (when)

• Weakness: Spatially locating neural activity (where)

event related potentials

Sources of Evidence About the Brain

Data from Electrical Recordings

In EEG’s, the brief response to any sensory or motor event

specific stimuli

Sources of Evidence About the Brain

Data from Electrical Recordings

Coding

Explains how some information is represented (or coded) by neurons. Specific neurons can, in some cases, represent…

chemical effects, electrical stimulation, gene manipulation

Manipulations of Brain Function

Brain function can also be studied through techniques that manipulate the functions. What are they? (3)

correlational

Manipulations of Brain Function

The Power of Combining Techniques

The problem of most neuroimaging techniques used to study brain activity and structures is that they only provide what kind of data?

transcranial magnetic stimulation

Manipulations of Brain Function

The Power of Combining Techniques

One source of causal data is a technique that uses magnetic pulses to activate neurons; produces temporary lesions

cerebral cortex

Localization of Function

The largest portion of the human brain w/a thin later of tissue covering the cerebrum

• Regions include motor areas, sensory areas, & association areas

primary motor projection areas

Localization of Function

The Cerebral Cortex

Motor Areas

Departure points in the motor cortex for signals that control muscle movement

• Contralateral control - topographical organization - more cortical coverage reflects greater motor precision

primary sensory projection areas

Localization of Function

Sensory Areas

Arrival points in the motor cortex for signals from the sensory

• Contralateral organization- cortical space assigned based on acuity

somatosensory area

Localization of Function

Sensory Areas

An area in charge of skin sensations; parietal lobe

primary auditory cortex

Localization of Function

Sensory Areas

The cortex in charge of auditory sensations; temporal lobe

primary visual cortex

Localization of Function

Sensory Areas

The cortex in charge of visual sensations

association areas

Localization of Function

Approx 75% of the cerebral cortex; contains many specialized subregions

• Damage can result in apraxia, agnosia, unilateral neglect syndrome, aphasia

apraxia

Localization of Function

Association Areas

Problems with initiation or organization of voluntary action

agnosia

Localization of Function

Association Areas

Problems with identifying familiar objects, typically one modality

unilateral neglect syndrome

Localization of Function

Association Areas

Problems in which one visual hemifield is ignored

aphasia

Localization of Function

Association Areas

Problems producing or understanding language