Looks like no one added any tags here yet for you.
the human brain is divided into 3 main structures…
the hindbrain
the midbrain
the forebrain
The Hindbrain
located at the very top of the spinal cord
contained structures crucial for controlling key life functions like heart rate
plays an essential role in maintaining posture and balance
helps control level of alertness
includes…
cerebellum
pons
medulla
Cerebellum
largest area of the hindbrain
coordination of bodily movements
various other roles
damage: cause problems in spatial reasoning, discriminating sounds, and integrating input received from various sensory systems
Pons
main connection between cerebellum and the rest of the brain
Medulla Oblongata
breathing
heart rate
The Midbrain
important part in coordinating the precise movements of the eyes as they explore the visual world
contain circuits that relay auditory information from the ears to areas in the forebrain where information is processed and interpreted
help to regulate the experience of pain
relays information between the brain and the spinal cord
Cerebral Cortex
thin layer covering cerebrum but includes lots of cortical tissue
makes up 80% of the human brain
deepest groove in the surface of the cortex is longitudinal fissure
runs from the front to the back and separates the left and right hemispheres
other fissures divide the cortex into 4 lobes
frontal lobes (central fissure separates them from parietal lobes)
parietal lobes (lateral fissure separates them from temporal lobes)
temporal lobes
occipital lobes
Subcortical Structures
thalamus
hypothalamus
limbic system
amygdala
hippocampus
Thalamus
acts as a relay station for most sensory information going to the cortex
Hypothalamus
crucial role in behaviours that serve biological needs (eating, drinking, sex)
Limbic System
essential for learning and memory
includes amygdala and hippocampus (HM had large portions of these removed)
Amygdala
key role in emotional processing
greater activation of amygdala while witnessing an event will lead to better, longer-lasting memories
Commissures
thick bundles of fibers that carry information back and forth between the two hemispheres
Corpus Callosum
largest commissure
sometimes there are medical reasons to sever the corpus callosum and some other commissures (like for epilepsy)
patient then becomes a split brain patient
Split-Brain Patient
communication between the two halves is severely limited
research with these patients has taught us a lot about the specialized function of the brain’s two hemispheres
confirmed that many aspects of language are in the left hemisphere
confirmed that right hemisphere is crucial for a number of tasks involving spatial judgement
important not to overstate the contrast between the two halves
Neuropsychology
the study of the brain’s structures and how they relate to brain function
study of cases about brain damage through accident, disease or birth defect falls within the domain of neuropsychology
consequences of brain lesions depend on which hemisphere is damaged
Clinical Neuropsychology
specialty of neuropsychology
seeks (among other things) to understand the functioning of intact, undamaged brains by means of careful scrutiny of cases involving brain damage
Neuroimaging techniques
produce precise, 3D pictures of a living brain
structural and functional imaging
Structural Imaging
generating a detailed portrait of the shapes, sizes, and portions of the brain’s components
CT Scan
MRI
Functional Imaging
tells us about activity levels throughout the brain
PET Scan
fMRI
fMRI
measures oxygen content in blood flowing through each region of the brain to provide an index of the level of activity in that region (can offer a precise picture of the brain’s moment-by-moment activities)
neurons function
main function is to communicate with one another using chemical signals called neurotransmitters
also communication within a neuron
neurons get signals from one end of the cell to another with electrical pulses
Electroencephalography
recording of voltage changes occurring at the scalp that reflect activity in the brain underneath
creates an EEG: recording of the brain’s electrical activity
often used to study broad rhythms in the brain’s activity
Power of Combining Techniques
each technique has its strengths and weaknesses, we deal with limitations by combining techniques
seek data from multiple sources to make a whole image
combine EEG with fMRI so we can see when and where activity took place in the brain
combine fMRI with CT so that findings about brain activation can be linked to a person’s brain anatomy
How to get around only correlational data from neuroimaging techniques
ex; Fusiform Face Area is especially active whenever a face is being perceived so there is a correlation between a mental activity and a pattern of brain activity
does this mean FFA is needed for face perception?
we can get additional data from lesions - if a brain area is damaged and disrupts a particular function it’s an indication that the site does play some role in supporting that function
Transcranial Magnetic Stimulation
technique that creates a series of strong magnetic pulses at a specific location on the scalp and these pulses activate the neurons directly under this scalp area
can be used as a way to see what happens when we stimulate certain neurons
because it disrupts the ordinary function of these neurons it creates a temporary lesion which allows us to identify what functions are compromised when a particular bit of brain tissue is briefly turned off
Localization of Function
finding out where functions originate in the brain
reveals enormous overlap between the brain structures needed for two activities
Primary projection areas
primary motor projection areas
primary sensory projection areas
Primary Motor Projection Areas
“departure points” for signals leaving the cortex and controlling muscle movement
evidence comes from studies where investigators apply mild electrical current to this area in anesthetized animals
stimulation produces specific movement depending on the site it’s applied to
show a pattern of contralateral control (stimulation to left hemisphere leads to movement on the right side of the body and vice versa)
Primary Sensory Projection Areas
“arrival points” for information coming from the eyes, ears and other sense organs
Why are they called projection areas?
because they seem to form “maps” of the external world with particular positions on the cortex responding to particular parts of the body or locations in space
located on a strip of tissue towards the back of the frontal lobe
Sensory Areas
information arriving from the skin senses is projected to a region in the parietal lobe just behind the motor projection area (somatosensory area)
Sensory Projection Areas
differ from each other in important ways but also have features in common and they parallel the attributes of the motor projection area
provides a “map” of sensory environment
includes somatosensory area, visual area, auditory area
Somatosensory Area
each part of the body’s surface is represented by it’s own region on the cortex
areas that are near to one another are represented by similarly nearby areas in the brain
Visual Area
each region of visual space has its own cortical representation
adjacent areas of visual space are usually represented by adjacent brain sites
Auditory Projection Area
different frequencies of sound have their own cortical site
adjacent brain sites are responsive to adjacent frequencies
Assignment of Cortical Space
governed by function, not by anatomical proportions
in the parietal lobes: parts of the body that aren’t very discriminating to touch get relatively little cortical area (even is they’re physically large) and more sensitive areas (lips, tongue, fingers) get more space
in the occipital lobes: more cortical surface is devoted to the fovea (part of the eye most sensitive to detail)
in auditory areas: some frequencies of sound get more cerebral coverage than others
Association Areas - brain space
motor and sensory areas make up only about 25% of the human cerebral cortex, the rest is association cortex
Apraxia cause
caused by lesions in the frontal lobe
Agnosia cause
caused by lesions in the occipital or rearmost parietal lobe
usually affect one modality only
visual agnosia: can recognize a fork by touching it but not by looking at it
auditory agnosia: unable to identify familiar voices but can still recognize the face of the person talking
Unilateral Neglect Syndrome
produce lesions (usually in parietal lobe) where individuals seem to ignore half of the visual world
shave only half their face
eat food on half the plate
read only half of words
Aphasia
lesions in areas near the deep groove that separates the frontal and temporal lobes can result in language disruptions
The Brain’s Major Divisions
Hindbrain
Midbrain
Forebrain
Subcortical Structures
Forebrain
higher order processing
most interesting brain region
structure that surrounds the midbrain and most of the hindbrain
cerebral cortex
outer surface (grey matter)
folds increase volume
two hemispheres (separated by the corpus callosum
4 lobes in each
some specialization
Scanning Methods
Event Related Potentials (ERP)
Computerized Axial Tomography (CAT/CT Scans)
Positron Emission Tomography (PET Scans)
Magnetic Resonance Imaging (MRI & fMRI Scans)
Event Related Potentials (ERPs)
electrical activity on the scalp
measure changes in the EEG in the brief periods just before, during and after the event
patterns of negative and positive voltage
excellent temporal resolution (the “when”)
can tell exactly when part of the brain is activated
poor spatial resolution (the where”)
not great for showing exactly where
Computerized Axial Tomography (CAT/CT Scan)
series of x-rays taken at various angles then reconstructed in a computer to create an image
allows for the study of anatomy and structure, but not function
Positron Emission Tomography (PET Scan)
measures blood flow, often via radioactive glucose tracers
measures brain activity over time (not instantaneous)'
fair spatial resolution (where)
hard to tell when structures are small and close together
Poor temporal resolution (when)
Magnetic Resonance Imaging (MRI and fMRI)
use a giant magnet to measure fluctuations in the magnetic fields
fMRI measures rapid changes in blood and oxygen flow in the brain
helps determine localization of function (excellent spatial resolution)
weak temporal resolution
Broca’s and Wernicke’s Areas
located in the left hemisphere
both involve language
Broca - language production
Wernicke- language comprehension
Broca’s Aphasia
expressive aphasia
disrupted production a-grammatical speech
Case Study - Mike
broca’s aphasia
struggles to produce his speech, it takes a lot of effort to get the words out
the speech he does produce is very basic, sparse and is often single words
his ability to understand language is not impaired
he listens to himself talk
Wernicke’s Aphasia
receptive aphasia
difficulty understanding
speech is often a “word salad”
Case Study - Bryon
good prosody - speech sounds fluent and flow at a normal pace
his sentences are relatively well-structured, but don’t convey much information
uses nouns and verbs in grammatically correct spots
occasionally makes up words (neologisms)
has some difficulty understanding what is being said to him