View
240
Download
1
Tags:
Embed Size (px)
Citation preview
2
The Brain
The Brain The Tools of Discovery
Older Brain Structures
The Cerebral Cortex
Our Divided Brain
Left Brain-Right Brain
3
The Brain
Techniques to Study the Brain
Brain lesion experimentally
destroys brain tissue to study animal behaviors after such destruction.
Hubel (1990)
4
Clinical ObservationNeurological and psychiatric diseases
are now catalogued.T
om L
anders/ Boston G
lobe
5
Electroencephalogram (EEG)An amplified recording of the electrical waves
sweeping across the brain’s surface, measured by electrodes placed on the scalp.
AJ P
hoto/ Photo R
esearchers, Inc.
6
PET ScanPET (positron
emission tomography) Scan a visual display of brain activity that detects a radioactive form of glucose while the brain performs a
given task.
Courtesy of N
ational Brookhaven N
ational Laboratories
7
MRI & fMRI Scan
MRI (magnetic resonance imaging) uses magnetic
fields and radio waves that reveal structure.
fMRI (functional MRI) reveals brain’s functioning
by making a sort of “movie” of changes in the activity of the brain and
structure.
Both photos from Daniel Weinberger, M.D., CBDB, NIMH
James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations
ventricular enlargement in a schizophrenic patient.
brain regions when a participant lies.
8
Older Brain Structures
Brainstem the oldest part of the brain, beginning where the spinal cord swells and enters the skull.
Responsible for automatic survival functions.
9
Brain Stem
Medulla [muh-DUL-uh] base of the brainstem, controls heartbeat and
breathing.
Reticular Formation – a nerve network inside
the brainstem that plays an important role in controlling arousal.
10
Brain Stem
Thalamus [THAL-uh-muss] the brain’s
sensory switchboard, located on top of the brainstem. It directs
messages to the sensory areas in the cortex and transmits
replies to the cerebellum and
medulla.
11
The “little brain” attached to the rear of the
brainstem. It helps coordinate voluntary
movements and balance along with some
nonverbal learning and memory.
Cerebellum
12
Limbic System a doughnut-shaped system of neural
structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and
drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.
The Limbic System
13
Amygdala
Amygdala [ah-MIG-dah-la] two almond-
shaped neural clusters linked to emotion of
fear and anger.
14
Hypothalamus
Hypothalamus lies below (hypo) the thalamus; directs
several maintenance activities like eating,
drinking body temperature, and emotions. Helps
govern the endocrine system via the
pituitary gland.
15
Rats cross an electrified grid for
self-stimulation, when electrodes are placed in the reward center
(hypothalamus) .
When the limbic system is manipulated rat will navigate fields
or climb up a tree.
Reward Center (nucleus accumbens)
Sanjiv T
alwar, S
UN
Y D
ownstate
16
The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. The body’s
ultimate control and information processing center.
18
Structure of the Cortexfrontal lobes (forehead) –
planning, organization,
impulse controlparietal lobes (top to rear head) – touch, taste, temperature
occipital lobes (back head) – vision
temporal lobes (side of head) – auditory and higher visual
processing.
19
Functions of the CortexMotor Cortex area at the rear of the frontal
lobes controls voluntary movements. Sensory Cortex (parietal cortex) receives information
from skin surface and sense organs.
20
Visual Function
Functional MRI scan shows the visual
cortex activates as the subject looks at faces.
Courtesy of V
.P. Clark, K
. Keill, J. M
a. M
aisog, S. Courtney, L
.G.
Ungerleider, and J.V
. Haxby,
National Institute of M
ental Health
21
Auditory Function
Functional MRI scan shows the auditory cortex is active in
patients who hallucinate.
22
More intelligent animals have increased “uncommitted” or association areas of the
cortex.
Association Areas
23
Spatial neglect - damage to the association areas of the right hemisphere resulting in an inability to recognize objects or body parts in the left visual field.
24
LanguageAphasia is an impairment of language, usually caused by left hemisphere damage either to
Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding).
25Menu
Language is primarily a left hemisphere activity for most individuals
LO 2.13 Left side and right side of brain
27
Brain is sculpted by our genes but also by our experiences.
Plasticity refers to the brain’s ability to modify itself after some type of injury or illness.
The Brain’s Plasticity
28
Our Divided Brain – two hemispheres
Left hemisphere - Sequential
processing for analytic reasoning
and language, reading, writing,
calculations, comprehension skills, and thus termed as the
dominant brain in the 1960s.
Right hemisphere – Simultaneous processing, nonverbal, visual-spatial, melody, pitch, emotional content of language
29
Splitting the BrainA procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Corpus Callosum
Ma
rtin M
. Ro
the
r
Courtesy of T
erence William
s, University of Iow
a
30
Split Brain Patients
With the corpus callosum
severed, objects (apple)
presented in the right visual field can be named. Objects (pencil) in the left visual
field cannot.
32Menu
Split-brain subjects stared at a dot and viewed a composite of two faces (A). When asked what they saw, subjects chose the child—the image sent to the verbal left hemisphere (B). But when subjects pointed to the face with the left hand, they chose the woman with glasses—whose image was received by the right hemisphere (C) (Levy et al., 1983).
LO 2.13 Left side and right side of brain
34
Non-Split Brains
People with intact brains also show left-right hemispheric differences in mental abilities.
A number of brain scan studies have shown normal individuals engage their right brain when they engage in a perceptual task, and
left brain when carrying out a linguistic task.
35
Brain Organization & Handedness
Is handedness inherited? Yes. Archival and historic studies to modern medical studies
point that right hand is preferred. This suggests, genes and/or prenatal factors
influence handedness.