Neuroscience

COGNITIVE NEUROSCIENCE
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Cognitive Neuroscience

•Field of study linking the brain and other aspects of the nervous system to cognitive processing , and ultimately, to behavior.

Cognitive Neuroscience
• Localization of function
– refers to the specific areas of the brain that control specific skills or behaviours.

• Nervous System
– basis for our ability to perceive, adapt & interact with the world around us. – receive, process, and respond

Human Brain
•Consumes 20% of body’s energy •2% of body mass •12-20 watts of power •Controls thoughts, emotions, motivations •reactive and directive

FETAL BRAIN DEVELOPMENT

Brain Regions

Forebrain, Midbrain, Hindbrain

FOREBRAIN
• Cerebral Cortex
– receiving and processing of sensory information

• Basal Ganglia
– Collection of neurons for motor functioning

• Limbic System-

memory, learning, emotion, motivation

– Septum, Amygdala, Hippocampus

• Thalamus
– relays incoming sensory information through groups of neurons that project the appropriate region in the cortex

• Hypothalamus
– Regulates behavior related to species survival

MIDBRAIN
• Reticular Activating System • Superior Colliculi (on top)
– vision

• Inferior Colliculi (below)
– auditory

• • • •

Gray Matter Red Nucleus Substantia Nigra Ventral Region

HINDBRAIN
• Medulla Oblongata
– breathing, swallowing, digestion, nerves ‘ crossing juncture

• Pons
– relay station containing neural fibers

• Cerebellum
– “little brain” – Coordination, balance, muscle tone, procedurerelated movements

STRUCTURES OF THE BRAIN

HEMISPHERIC SPECIALIZATION

Paul Broca
- Broca’s Area contributes to speech.

Carl Wernicke

- Wernicke’s Area * contributed to language comprehension.

Karl Spencer Lashley

• Father of Neuropsychology • Found that implantations of crudely built electrodes in apparently identical locations in the brain yielded different results.

Roger Sperry

- Nobel Prize Winner - Argued that each hemisphere behaves in many respects like a separate brain.

FUNCTIONAL AREAS OF THE CORTEX

SPLIT BRAIN surgical separation of the hemispheres of the brain by severing the corpus callosum: splitbrain operation to prevent epileptic seizures.

LOBES OF THE BRAIN

HOMUNCULUS OF THE PRIMARY MOTOR CORTEX
• v

OPTIC TRACT AND PATHWAYS TO THE PRIMARY VISUAL CORTEX

COMPOSITION OF A NEURON

NEUROTRANSMITTERS
NEUROTRANSMITTER
• Acetylcholine (Ach) Monoamine neurotransmitter • Dopamine (DA) • Epinephrine and Norepinephrine • Serotonin • GABA (gammaaminobutyric acid) Glutamate

DESCRIPTION
Monoamine neurotransmitter Synthesized from choline Monoamine neurotransmitter Synthesized from tyrosine Monoamine neurotransmitter Synthesized from tyrosine Monoamine neurotransmitter Synthesized from tryptophan

Amino acid neurotransmitter
Peptide chains serving as neurotransmitters

• Neuropeptides

POSTMORTEM STUDIES
• From Latin, which means “after death” • Studies start during the lifetime of a person. • Researchers observe and document the behavior of people who show signs of brain damage while they are alive. • Researchers may be able to trace a link between an observed type of behavior and anomalies in a particular location in the brain. • Lesioning techniques cannot be performed on the living brain.

STUDYING LIVE NONHUMAN ANIMALS
• Single-cell Recording • Selective Lesioning

- Researchers have found neurochemical ways to induce lesions in animals’ brains by administering drugs that destroy only cells that use a particular neurotransmitter.

• Genetic Knockout Procedures

STUDYING LIVE HUMANS
Electrical Recordings

Electroencephalograms

Event-related Potential

STUDYING LIVE HUMANS
Electrical Recordings Method Procedure

Suitable for Humans?

Advantages

Disadvantages

EEG

Changes in electrical potentials are recoded via electrodes attached to scalp. Changes in electrical potentials are recoded via electrodes attached to scalp.

Yes

Relatively noninvasive

Imprecise

ERP

Yes

Relatively noninvasive

Does not show actual brain images

Static Imaging Techniques

Two kinds of MRIs: - Structural MRI - Functional MRI

Metabolic Imaging
Positron Emission Tomography and Transcranial Magnetic Stimulation

Method

Procedure
Participants ingest a mildly radioactive form of oxygen that emits positrons as it is metabolized. Changes in concentration of positrons in targeted areas of the brain are then measured. Involves placing a coil on a person’s head and then allowing an electrical current to pass through it. The current generates a magnetic field. This field disrupts the small area beneath it. The researcher can then look at cognitive functioning when the particular area is disrupted.

Suitable for Humans?

Advantages

Disadvantages

PET

Yes

Shows images of the brain in action

Less useful for fast processes

TMS

Yes

Enables researcher to pinpoint how disruption of a particular area of brain affects cognitive functioning

Potentially dangerous if misused

Functional Magnetic Resonance Imaging and Magnetoencephalography

Method

Procedure Creates magnetic field that induces changes in the particles of oxygen atoms. More active areas draw more oxygenated blood than do less active areas in the brain. The differences in the amounts of oxygen consumed form the basis for fMRI measurements. Involves measuring brain activity through detection of magnetic fields by placing a device over the head.

Suitable for Humans?

Advantages

Disadvantages

fMRI

Yes

Shows images of the brain in action; more precise than PET

Requires individual to be placed in uncomfortable scanner for some time

MEG

Yes

Requires Extremely expensive precise spatial machine not and temporal readily available solution to researchers