The Central Nervous System

The Central Nervous System

Spinal cord- Interface between the

peripheral and central nervous systems

- Carries reflexes, sensory, and motor information

- 31 pairs specialized nerves (brain has 12 pairs – the cranial nerves)

The BrainSquishyWeighs about 3

poundsMost complex

structure in known universe.

So how do you study this thing?

Studying the brainSurgical – can implant electrodesElectrical and imaging Electrical –

Electroencephalography (EEG) Electromyography (EMG)

Electroencephalogram (EEG)

recording of the waves of electrical activity that sweep across the brain’s surface

measured by electrodes placed on the scalp

NeuroimagingCT (computed tomograph) Scan

a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CAT scan for Computerized Axial Tomography.

PET (positron emission tomograph) Scan a visual display of brain activity that detects where a

radioactive form of glucose goes while the brain performs a given task.

PET Scan

NeuroimagingMRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer – generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.

Also known as fMRI (functional magnetic resonance imaging) Can do real-time scans to see the brain at work.

MRI Scan

Da’ brainMajor parts :

Hindbrain Midbrain Subcortical forebrain Cerebral cortex

The Hindbrain

Brainstem the oldest part and central core of the brain,

beginning where the spinal cord swells as it enters the skull

responsible for automatic survival functionsMedulla [muh-DUL-uh] (aka Medulla

Oblongata) base of the brainstem controls heartbeat and breathing

The Hindbrain

Pons

“switchboard” connecting cerebral cortex to cerebellum

Reticular Formation(extends into midbrain)

a nerve network that plays an important role in controlling alertness

The Hindbrain (pons & medulla plus some other junk…)

The Hindbrain

Cerebellum [sehr-uh-BELL-um] the “little brain”

attached to the rear of the brainstem

it helps coordinate voluntary movement and balance

The Midbrain

Involved in vision and hearing Parts of reticular formation, eye & body

movement Includes the substantia nigra that

produces dopamine.

The Subcortical Forebrain

Thalamus [THAL-uh-muss] the brain’s sensory switchboard, located on

top of the brainstem directs messages to the sensory receiving

areas in the cortex and transmits replies to the cerebellum and medulla

Basal ganglia Near the thalamus Movement, posture, also certain types of

judgments

The Subcortical Forebrain

Electrode implanted in reward center in hypothalamus

The Cerebral Cortex

Cerebral Cortex the intricate fabric of interconnected neural

cells that covers the cerebral hemispheres the body’s ultimate control and information

processing centerGlial Cells

cells in the nervous system that are not neurons but that support, nourish, and protect neurons

The Cerebral Cortex

Frontal Lobes involved in speaking and muscle movements

and in making plans and judgmentsParietal Lobes

include the sensory cortexOccipital Lobes

include the visual areas, which receive visual information from the opposite visual field

Temporal Lobes include the auditory areas

The Cerebral Cortex

The Cerebral Cortex

Motor Cortex area at the rear of the frontal lobes that

controls voluntary movements (aka primary motor area)

Sensory Cortex area at the front of the parietal lobes that

registers and processes body sensations (aka primary somatosensory area)

The Cerebral Cortex

The Cerebral Cortex

Functional MRI scan of the visual cortex activated by light shown in the subject’s eyes`

Visual and Auditory Cortex

Auditorycortex

Visualcortex

Association Areas

areas of the cerebral cortex that are not involved in primary motor or sensory functions

involved in higher mental functions such as learning, remembering, thinking, and speaking

The Cerebral CortexAphasia

impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)

Broca’s Area an area of the left frontal lobe that directs the muscle

movements involved in speechWernicke’s Area

an area of the left temporal lobe involved in language comprehension

Specialization and Integration

Specialization and Integration

Brain activity when hearing, seeing, and speaking words

Brain Reorganization

Plasticity the brain’s capacity for modification as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development

Our Divided Brain

Hemispheric specialization (or “cerebral lateralization”)

Found in lots of species (even beta fish!)

True, and important, but don’t overdo it…

What most people believe...

Our Divided Brain

Corpus Callosum largest bundle

of neural fibers

connects the two brain hemispheres

carries messages between the hemispheres

Corpus callosum

Our Divided Brain

The information highway from the eyes to the brain

Split Brain

a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them

Split Brain

“Look at the dot.” Two words separatedby a dot are momentarily projected.

“What worddid you see?”

or

“Point withyour left hand to theword you saw.”

Disappearing Southpaws

The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).

The percentage of lefties sharplydeclines with age

10 20 30 40 50 60 70 80 90Age in years

14%

12

10

8

6

4

2

0

Percentage ofleft-handedness

Cerebral cortex

Left hemisphere

Right hemisphere

Corpuscallosum

Thalamus

Hypothalamus

Pituitary

Reticularformation

Medulla

Spinalcord

Cerebellum

Amygdala

Hippocampus

Cerebral cortex Limbic system Brainstem