Older Brain Structures

THE BRAIN☺

Older Brain Structures

Older Brain Structures

• Brainstem = Medulla + Pons + Reticular Formation

• Thalamus (located on the top of the brainstem)

• Cerebellum

• Limbic System (Amygdala + Hippocampus +

Hypothalamus)

• Pituitary Gland

Hindbrain

•

Major structures =

medulla

pons

Hindbrain

•

The Brainstem

= the

pons, the medulla, and

the reticular formation.

• Medulla:

• above the spinal cord

inside the skull. Extension of the spinal cord

Hindbrain

•

Cerebellum

•

Little Brain

• Contributes to the control of movement

Midbrain

• The midbrain is the

smallest region of the brain.

• It acts as a sort of relay

station for auditory and visual information.

• The midbrain controls

many important functions such as the visual and

Forebrain

• 2 Subdivisions

• Diencephalon (Between)-

Major structures -

thalamus, hypothalamus

• Telencephalon

Forebrain

• Thalamus – The brain’s sensory switchboard

located on the top of the brainstem.

• Resembles two avocados

joined side by side

• Most sensory info goes

through the thalamus to the cortex

Forebrain

• Limbic system - olfactory bulb, hypothalamus,

hippocampus, amygdala

• Structures that form a

border around the brainstem

Hippocampus

• Part of the limbic system

Forebrain

• Hypothalamus – (below the thalamus) Directs eating, drinking, body temp.

• Influences the pituitary gland

• Helps govern the endocrine system via the pituitary gland

• The Hypothalamus is linked

Forebrain

• Pituitary gland -

endocrine gland

• Attached to the base of the

hypothalamus by a stalk

• Called the “master gland”

• Secretions control the

timing and amount of

The Ventricles

•

Fluid filled cavities

within the brain

•

Contain cerebrospinal

fluid (CSF)

•

Cushions against shock

•

Provides buoyancy,

helps support weight

•

Provides a reservoir of

The Ventricles

• Hydrocephalus - obstructed CSF flow, excess

accumulation, pressure on the skull bones, overgrown head

• Meninges - membranes surrounding the brain and spinal cord

Cerebrum

• Cerebrum = the two

hemispheres that contribute to 85% of your brain’s

Forebrain

• Cerebral Cortex = outermost portion

• Think of bark on a tree

The Cerebral Cortex

Cerebral Cortex

• A thin surface layer of

interconnected neural cells covering the cerebrum

• CC = The body’s ultimate control and information center.

• CC = Your body’s “thinking crown”

• As we move up the chain

Cerebral Cortex

•

CC = 20 billion nerve cells and 300 trillion

synaptic connections.

•

Supporting these cells are 9 times as many

glial cells (support, nourish, and protect).

glia cells may also play a role in learning

and thinking.

•

EINSTEIN had lots and lots of glia cells

LOBES

• Frontal – speaking, muscle movements, making plans

and judgment

• Parietal – receives sensory input for touch and body position

• Occipital – receives info from visual fields

• Temporal – receives auditory info

• Association Areas – areas of the cerebral cortex that

are not involved in primary motor or sensory

functions; rather, they are involved in higher mental functions such as learning, remembering, and

Motor Cortex

•

An area in the rear of the frontal lobe

that controls voluntary movement.

•

Stimulating parts of this region in the

left hemisphere or right hemisphere

cause movements of specific body

parts on the

opposite

side of the body.

Sensory Cortex

•

An area at the front of the parietal lobe that

registers and processes body touch and

movement sensations.

•

Penfield also mapped the cortical areas that

specializes in receiving info from the skin senses

and from the movement of body parts.

•

If stimulating a specific area, a person will feel

being touched in the corresponding area.

•

The more sensitive the area (your thumb + lips),

Questions pp.74 - 91

• How does the brain process language? What are the

names of the regions thought to be involved in language? What proof do we have to support our understanding of how these regions function? (i.e. What seems to happen when these regions are

damaged?).

Aphasia

•

Impairment of language,

•

Broca’s Area

= Controls language

expression – an area usually in the left

frontal lobe, that

directs the muscles

movements involved in speech.

(If

damaged – disrupts speaking)

•

Wernicke’s Area

= Controls language

reception

– a brain area involved in

language comprehension and

expression; usually in the left temporal

lobe. (If damaged – disrupts

Processing Language

•

Hearing Words

– Auditory cortex and

Wernicke’s area

•

Seeing Words

– Visual Cortex and angular

gyrus. (

If AG is damaged, one cannot read

aloud. Can still speak and understand language

though.)

•

Speaking Words

– Broca’s area and motor

Speaking the Written Word Speaking the Heard Word

To speak a word that is read, information must first get to the primary visual cortex. From the primary visual cortex,

information is transmitted to the posterior speech area, including Wernicke's area. From Wernicke's area, information travels to

Split Brain Surgery on

Epileptic Patients

•

Has helped reveal how the two

hemispheres function

•

Damage to the brain from accidents,

Severed Corpus Callosum

Split Brain – p. 88

• More active when

deliberating or making decisions

Right Brain

• Perceptual Tasks

• Excels at making inferences

• Sense of self

• Helps make meaning clear by modulating speech

• Is more engaged with quick, intuitive responses

• Better at copying drawings and recognizing faces.

Split Brain Experiment

Split Brain Studies

Pleasure and Addiction

•

Intracranial electrical brain

stimulation self-administration

experiments with rats.

•

Rats will press the lever as rapidly as

The Reward System

•

The dopamine

pathway from the

VTA to the nucleus

accumbens is

critical for

addiction.

•

Animals with lesions

in these brain

Nucleus Accumbens

•

f(MRI) and (PET)

scans – nucleus

accumbens in cocaine

addicts light up when

they are offered a line

of cocaine or shown

videos or photographs

of drug use.

•

Brain scans of cocaine

addicts, alcoholics, and

compulsive gamblers

Dopamine

• All drug abuse directly or indirectly increases the

amount of dopamine signaling in the nucleus accumbens.

• Cocaine – blocks dopamine uptake

• Nicotine – induces VTA cells to releases dopamine into

the nucleus accumbens.

• Alcohol and Opiates – enhance dopamine release by

The Reward System

• A key component of the

reward circuitry is the

mesolimbic dopamine system,

which is a set of nerve cells that originate in the ventral

tegmental area (VTA), near

the base of the brain.

• These cells send projections

to target regions in the front of the brain – most notable the nucleus accumbens.

• Those VTA neurons

communicate by dispatching

dopamine to receptors on

Neuroimaging Techniques

• CT (Computed Tomography) scan

• EEG (electroencephalpgram)

• PET (positron emission tomography) scan

• MRI (magnetic resonance imaging)

Neuroimaging Techniques

• The tips of modern microelectrodes are so small that

they can detect electrical pulse in a single neuron.

EEG

(Electroencephalogram)

An amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp.

CT (computed tomography)

• 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

PET (positron emission

tomography) Scan

A visual display of brain activity that detects where a radioactive form of glucose goes while the brain

performs a given task.

Active neurons are glucose hogs.

MRI (magnetic resonance

imaging)

• A technique that uses

magnetic fields and

radio waves to produce computer generated images of soft tissue.

fMRI (functional MRI)

• A technique for

revealing blood flow and, therefore, brain activity by comparing successive MRI scans.

• fMRI scans show brain

function as well as its structure.

Chapter 3 Section 3C

• What do twin studies reveal about heredity and