Biological Psychology - Brain structure and function

Neuroanatomy

The study of the structure of the nervous system

Neurophysiology

The study of the functions and activities of the nervous system

Neurochemistry

The study of chemical basis of neural activity

Neuroendocrinology

The study of interactions between the nervous system and the endocrine system

Neuropathology

The study of nervous system disorders

Neuropharmacology

The study of the effects of drugs on neural activity

Afferent nerves

Sensory nerves (input) - e.g. signal sent to spinal chord in CNS in response to a sensory input like a hand on a hot flame

Efferent nerves

Motor nerves (output) - signal sent from spinal chord in CNS to muscles to contract and move hand away from hot flame

What is the difference between the autonomic and somatic nervous systems?

Autonomic NS controls automatic/involuntary motor actions like heart beat and breathing vs somatic NS controls voluntary movements

Sympathetic nervous system

• Autonomic motor nerves that prepare us for action (fight or flight)

• Response to a stressor, e.g. heart rate increases, bronchi dilate, secretion and peristalsis inhibited etc

• Mobilises energy

Parasympathetic nervous system

• Autonomic motor nerves that prepare us to relax

• Peaceful resting state, e.g. digestion increases (peristalsis), heart rate slows, bile secreted etc

• Energy is conserved

Neuraxis

The direction in which the CNS lies in relation to the spinal chord

Bipedalism

When the head of an animal goes in a different direction to the spinal chord (e.g. humans vs alligators - humans are an example of bipedalism)

Dorsal axis

Towards the back of the body or top of head

Anterior/Rostral axis

Toward the front end of the body (nose)

Ventral axis

Toward the front (belly) of the body or the bottom of the head

Posterior/caudal axis

Towards the tail

Medial axis

Towards the midline of the face and body

Lateral axis

Away from the midline of the face and body

Proximal

Close to CNS for example the shoulders

Distal

Far from the CNS e.g. fingers

Bilateral

On both sides of the body/head

Ipsilateral

On the same side of the body or head

Contralateral

On the opposite side of the body or head

Coronal sections

Like sliced bread, at equal intervals

Saggital sections

Chopped down the middle vertically

Horizontal sections

Cut horizontally across the middle, think of burger buns

Cross section

A slice taken at right angles to the neuraxis (spinal chord)

Midsaggital plane

The plane through the neuraxis perpendicular to the ground; divides the brain in two symmetrical halves

Transverse plane

Cross section of spinal chord

Horizontal plane

Horizontally cut in half like a burger

Meninges function

Collective name of the three membranes that protect the brain (Dura mata, arachnoid membrane, subarachnoid space)

Cerebrospinal fluid (CBF)

• Fluid that fills the subarachnoid space, the spinal chord and ventricles in the brain

• Provides cushioning and support for the brain

What happens if there’s not enough CBF?

Suffer headaches and pain because their sensitive brain is not protected by the fluid

What happens if there’s too much CBF?

Excess CBF is continually absorbed into subarachnoid space, and sinuses which run through dura mata and drains into jugular veins

What is the importance of the blood brain barrier?

The semi-permeable membrane separates blood from CSF, providing a barrier that prevents many toxins from entering the brain from the bloodstream. Some drugs can pass through while others can’t

Major brain structure - Myelencephalon (medulla)

• Located in most posterior hindbrain (brain stem), includes the medulla oblongata

• Largely comprises tracts between brain and spinal chord.

• If brain is cut above the medulla basic heart rate and breathing maintained, but any damage to the medulla itself is fatal

• Contains the reticular formation, involved in sleep, attention movement, and cardiac, circulatory and respiratory reflexes

Major brain structure - Metencephalon

• Located in hind brain also

• Contains pons and cerebellum

What are the pons of the brain?

Enlargement of medulla, contains pontine nuclei which contains coerugleus and dorsal raphe (linked with serotonin and noradrenalin)

What is the cerebellum?

Important for sensorimotor control - control of movements + cerebellum damage can cause problems with decision making and language as well as movement.

Mesencephalon

• Contains two divisions (tegmentum and tectum)

• Contains substantia nigra - important component of sensory motor system

What is the tectum?

• Dorsal midbrain

• Contains inferior colliculi (auditory information)

• Superior colliculi (visual-motor information)

What is the tegmentum?

• Posterior midbrain

• Contains PAG (Primary control centre for descending pain modulation) - main function is pain modulation

Telencephalon

Everything else - cerebral cortex, subcorticol structure, important fibre bundles

Cerebral cortex

• composed of small unmyelinated neurons

• Grey matter

• Contains convolutions (large=fissures, small=sulci, ridges between=gyri)

• 90% of it is the neocortex (6 layers, most new)

• 10% of it is the allocortex

Hippocampus

• 3 major layers

• Located at medial edge of cerebral cortex

• Major role in memory (spatial location memory)

Limbic system

• Circuit of midline structures that circle the thalamus

• Regulation of motivated behaviours

• Consists of mammillary bodies, hippocampus, amygdala, fornix, cingulate, septum

Basal Ganglia

• Motor system

• smooth voluntary movement control

• Degeneration leads to rigidity, tremor and slow movements in Parkinson’s disease

The Neocortex

• Makes up 90% of the cerebral cortex

• Has 6 layers (most developed in its number of layers and organisation of the cerebral tissues)

• Humans have large neocortex ratio, relating to complexity of behaviour.

Frontal lobe

Motor cortex, complex cognitive functions

Temporal lobe

Hearing and language, complex visual patterns

Parietal lobe

Somatic sensations e.g. touch, orientation, location of objects

Occipital lobe

Visual processing

The case of HM

• Man who suffered one general seizure a week and focal seizures everyday

• His temporal lobes were removed

• Generalized seizures stopped, focal seizures reduced significantly

• STM intact, memories from before the surgery intact, but couldn’t form any new LTM

Phineas Gage

• Worked in construction, pole went through his cheekbone and out his skull

• He remained conscious and able to recall what happened

• Hitting the frontal cortex meant a loss of social inhibitions so his personality changed dramatically, was sweet and caring then became cold and harsh