An Early History of Biopsychology

Plato: the mind is located in the brain

Franz Gall and Phrenology– Early 1800s– Read bumps on skull

to understand traits

Studying the Brain

Studying the brain through lesions or damaged areas

– “Ta” and Phineas Gage– Experiments in rats –

hypothalamus lesions Monitoring Electrical

Activity: the EEG– Electroencephalograms

provide information about cortical activity

– Record electrical activity of neurons on surface of brain (neural firing)

– A functional technique

Studying the Brain: Structural Neuroimaging Techniques

CT Scan (Computerized tomography)

– Computer-assisted x-ray of brain

– Used to create overall images of brain

MRI (Magnetic Resonance Imaging)

– Produces detailed pictures of soft tissue in brain

– Can focus on specific regions when CT cannot produce clear images

CT scan (top) and MRI (bottom) showing a tumor.

Studying the Brain: Functional Neuroimaging Techniques

PET (positron emission tomography)

– Image created by the rate at which radioactive glucose is metabolized

– Which areas of the brain are active during a particular activity

fMRI (functional MRI)– Combines structural and

functional techniques– Multiple images of brain created

during a particular task– Records changes in blood flow

to indicate regions of greater activity

Primitive Brain Structures

Brainstem– Oldest part of brain– Contains medulla, controlling heartbeat,

blood pressure and breathing– Also contains pons, which helps regulate

sensory information and facial expressions– Contains Reticular Formation (RF) for

alertness/arousal, sleep/wakefulness Thalamus

– Pair of egg-shaped structures on top of brainstem

– Routes all incoming sensory information except for smell to appropriate areas of brain

Cerebellum– “little brain” at read of brainstem– Controls coordination, balance, and muscle

tone

These parts of the brain are our “autopilot” so other regions can deal with higher-level “human” functions

The Limbic System

Located in between the primitive parts of the brain and the cerebral hemispheres

– Hippocampus processes new memories (case of H.M.)– Amygdala controls emotions such as aggression and fear –

in animals, the “attack” response (rat study)– Hypothalamus regulates hunger, thirst, body temperature

and sex drive – also controls pituitary gland Rat study – self-stimulation of “pleasure centers” Human implications? Mild pleasure, addiction tendencies?

Primarily, the limbic system processes drives, smell and various emotional responses

The Cortex

Part of the cerebrum, the two large hemispheres comprising 85% of brain weight

Wrinkled outer layer Why so convoluted? Higher level functions Designation of cortical

space and “higher level” animals?

Most highly evolved part of the human brain

Cortex Breakdown…

Each hemisphere is divided into 4 lobes

– Frontal lobe– Temporal lobe– Parietal lobe– Occipital lobe

The lobes are separated by deep convolutions known as fissures

Cortex Breakdown…

Occipital Lobes– Visual cortex– Damage?

Temporal Lobes– Auditory cortex– Auditory hallucinations?

Parietal Lobes– Primary sensory or

somatosensory cortex– Allocation of space?

Frontal Lobes– Most evolved – Motor cortex, which

allows us to move– Allocation of space?

Homunculous!

Motor and Sensory Cortex Revealed!

The Cortex: Association Areas

We only use 10% of our brains? Undifferentiated cortex Association areas

Association Areas

Any areas not dealing with our senses or muscle movements are called association areas.

Association Areas of Frontal Lobe

Deals with planning, maintaining emotional control and abstract thought.

Contains Broca’s Area.Broca’s Aphasia.

Phineas Gage: A Case Study in Frontal Lobe Association Area Damage

In 1848, railroad foreman Phineas Gage – accident!

No longer “himself”

Emotions, the frontal cortex, and the unchecked limbic system The skull of Phineas and rogue tamping iron,

displayed proudly at Harvard University’s medical school! For real!

Temporal Lobes

Contains Wernicke’s area.

Wernicke’s Aphasia.

Occipital Lobes

In the back of our head.

Handles visual input from eyes.

Right half of each retina goes to left occipital lobe and vice versa.

Specialization & IntegrationBrain activity when hearing, seeing, and

speaking words

Neuroplasticity

Brain’s to change and reorganize as a result of experience

Mark Rosenzweig’s (1922-2009) Rat Studies (1950s-60s)

Implications for humans?

Party!

Hey guys! Check out our phat crib!

Shafted again.

Neurogenesis?

Recent evidence has suggested that human brains may be able to generate new brain cells, known as Neurogenesis

Stem cell research?

The Two Hemispheres

Two halves are NOT identical Most have a dominant hemisphere – usually

the left, which controls the right side of the body

Both sides serve important functions, revealed by studying split-brain patients

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

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Split-Brain

Epilepsy, seizures and the corpus callosum

Reduction in epileptic seizures Different abilities in each

hemisphere The story of “Vicki” Michael Gazzaniga

Split Brain PatientsWith the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left

visual field cannot.

Divided Consciousness

Some Hemispheric Strengths

Left Hemisphere– Language in most

people: The cases of Ta of Charles Landry

– Logic– Right side of body

Right Hemisphere– Perception– Sense of self– Inferences

Hemispheric Dominance: Handedness

90% of humans are right-handed The 10% of left-handers show less predictable

patterns of hemispheric dominance Causes

– Genetics? – Fetal testosterone levels?– Learned?– Handedness and sexual orientation?

A closer look: a curse or an advantage?