The Brain
The Nervous System
The Brain: Structures
•	Meninges
•	Cerebral hemisphere
•	Lobes
•	Corpus callosum
•	Cerebral cortex
•	Sulci
•	Gyri
•	Ventricles
The Brain: Lobes
•	Occipital Lobes
•	Temporal Lobes
•	Parietal Lobes
•	Frontal Lobes
•	Sulci
•	Central sulcus
•	Lateral sulcus
The Occipital Lobes
•	At the back of the head
•	Functions include
•	Many aspects of vision
The Temporal Lobes
•	In front of the ears
•	Functions include
•	Vision
•	Hearing
•	Memory
The Parietal Lobes
•	Top, rear of the brain
•	Functions include
•	Attention
•	Spatial location
•	Motor control
The Frontal Lobes
•	Front of the brain (of course)
•	Functions include
•	Planning
•	Memory search
•	Motor control
•	Reasoning
•	Phineas Gage
The “Strips”
•	Somatosensory strip 
•	Front of parietal lobe
•	Motor strip
•	Rear of frontal lobe
•	Next to each other
•	Both are organized by body part
Split-Brain Research and Hemispheric Specialization
The Inner Brain
The Inner Brain
•	Thalamus
•	Hypothalamus
•	Hippocampus
•	Amygdala
•	Basal ganglia
•	Brainstem
•	Cerebellum
The Neuroendocrine System
Observing the Brain
•	Electrical activity
•	Electroencephalograph (EEG)
•	Visualizing structure
•	Computer-assisted Tomography (CT scan)
•	Magnetic Resonance Imaging (MRI)
•	Visualizing function
•	Positron Emission Tomography (PET)
•	Functional Magnetic Resonance Imaging (fMRI)
Observing the Brain
•	Brain damage
•	Lesion
•	Stroke
•	Stimulating the brain
•	Transcranial Magnetic Stimulation (TMS)
The problems with localization
•	Multiple sites – also an advantage
•	Coordination -- The car analogy
•	Irrelevant knowledge and parsing
•	The Phelps amygdala and race study
•	Amygdala lights up for white Ss with black faces
•	Fear, prejudice? Correlated with latter
•	But maybe apprehension
•	Familiar faces?
•	What have we learned
•	More “real” – the arrogance of biological approaches

Sex and the brain
•	One of the most complex human behaviors
•	Also illustrates interactions among many areas of the brain and behavior
•	Also have to consider male and female behavior separately
•	But in both cases begin with the hypothalamus
Male sexual behavior I
•	Input to the medial preoptic area 
•	Specifically the area called INAH3
•	Much larger in males than in females
•	Also larger in heterosexual than in homosexual men
•	Has a great number of androgen sensitive neurons -- testosterone
•	And also from amygdala areas concerned with aggression and assertive behavior
•	Stimulation from optic and perhaps smell centers of brain
Male sexual behavior II
•	The role of the hypothalamus
•	Stimulation increases sexual interest in male animals
•	Passes signals to cortex which controls relevant behaviors
•	Signals down the brainstem to the penis to produce an erection
Male sexual behavior III
•	Intercourse is partially under control of motor cortex but partially reflexive
•	At appropriate time the dorsomedial hypothalamus triggers ejaculation
•	Pleasure produced by massive release of dopamine 
•	And relaxation by oxytocin
•	Also implicated in pair bonding in animals
Coordination
•	Mostly this is well coordinated
•	But
•	Stimulation of DM hypothalamus (during epileptic seizures) can produce ejaculation without sexual arousal
•	Stimulation of septum can produce orgasm without pleasure
•	And failures of several circuits can produce impotence
Female sexual behavior I
•	Ventromedial hypothalamus (also site of hunger) rich in estrogen receptors
•	In animals produces female submissive behavior
•	Also increases blood flow to the genitals
•	And much of the rest is similar to males
•	Orgasm 
•	Pleasure
Beyond this enormous interactions
•	Projections into the frontal lobes produces not only initiation of sexual behavior but inhibition because of moral concerns
•	Frontal lobe damage often produces uninhibited sexual behavior
•	Stalkers
•	Temporal lobes also important in inhibition
•	Project into the VM hypothalamus (controlling both hunger and sexual behavior)
•	Damage may result in Kluver-Bucy syndrome
•	Compulsion to stuff things into mouth or copulate
Depression
•	Actually many, perhaps interlinked syndromes
•	Many studies with brain imaging
•	Generally many parts of the brain are under active
The serotonin hypothesis
•	Serotonin circuits are numerous
•	And diffuse
Problems with serotonin hypothesis
•	No one has identified which circuits are responsible for depression
•	And the SSRIs take several weeks to produce effects even though their chemical effect is immediate
•	Possible that depression is due more to number of serotonin receptors
•	Which take time to grow
Frontal lobe activity
•	Greatly diminished in depressed people
•	Especially those associated with feelings of agency
•	Self-willed action
Other deficits
•	Parietal and upper temporal lobes
•	Attention
•	Especially to outside world
•	Cingulate cortex
•	Front of brain along bottom edge of cortex
•	Many ties to limbic system
•	Pathways for nonconscious ideas and motives to frontal lobes
•	Probably an emotional control center
•	Over-excitement leads to mania
•	Also over-activity associated with paranoia and sense that everything is related
Areas of greater activity in depressed
•	Outside edge of prefrontal lobe
•	Associated with pulling information from memory
•	And in normals lights up when have sad thoughts
•	Parts of the thalamus which are connected to amygdala – negative emotions
•	Anterior cingulate – concentration, especially interior thoughts
Thus a possible cycle
•	Amygdala feeds negative thoughts to prefrontal lobes (consciousness)
•	Prefrontal pulls out memories that match the feeling
•	Anterior cingulate fastens on to them and keeps other things from gaining attention
•	Thalamus keeps everything firing away
•	And no sense of purpose or self agency
Are brain scans helpful
•	We already knew that depressed people have the basic symptoms
•	Lack of meaning in life
•	Fasten on negative memories
•	Little attention to outside world
•	So brain activity results not surprising
•	But does provide a kind of model for relationships
•	What causes what
•	And in what order
Problems
•	Other areas of the brain involving responses to stress are also implicated by not scanned
•	Doesn’t relate well to why SSRIs are effective
Stress hypothesis
•	Depression is hereditary
•	Also early abuse and neglect is a huge risk factor
•	Diathesis-stress hypothesis
•	Also explains frequent association of anxiety and depression 
•	And similar treatments
•	Implicates the hypothalamic-pituitary-adrenal axis (HPA)
The normal circuit
•	Fear stimuli come to amygdala  
•	Projects to certain areas of hypothalamus
•	Which releases CRH hormones
•	Which stimulates pituitary gland to release ACTH 
•	Which in turn stimulates the adrenal glands to release Cortisol
•	Evidence of HPA hyperactivity in depressed people
The normal HPA circuit
The failures of inhibitions
•	These circuits are functional for reactions to stress 
•	 fight or flight responses
•	But must be inhibited if stressful stimulus is reduced and after time
•	Normally the hippocampus does this
•	Responds to Cortisol at certain receptors 
•	Inhibits CRH release
Responses to massive or prolonged stress
•	Constant cortisol exposure causes hippocampus neurons to wither and die
•	Hence aren’t effective in inhibiting stress reactions
•	And a vicious cycle of stress making one more vulnerable to additional stress 
Explanation for depression?
•	The biological correlates are in place
•	But only correlates
•	Explains correlation between depression and anxiety
•	And importance of early experience
•	And why depression is a periodic
But problems
•	Does not explain why ordinary people are depressed
•	Or why it is genetic
•	Or why SSRIs and other anti-depressants work
•	Theoretically work on serotonin circuits
•	But some evidence that they also dampen HPA activity
•	No one knows why
•	New drugs under development