Chemical synapse + neurotransmitters

• Things you can do with a brain: Detect and transmit sensory signals - dozens of receptor cells respond to changes which are connected to sensory neurons.
• Interlude = change in detection of senses
• Sensory adaptation = Getting used to a specific stimulus
• Long, myelinated axon of sensory neurons from bosy enter spinal cord via dorsal root. Neurons transmitting precisely located info send axons to top of spinal cord (medulla) e.g. proprioception Neurons transmitting poorly localised info synapse with other neurons when entering cord

Sensory neurons from head send axons directly to brain via cranial nerves. Signals are transmitted via relay stations. At each, integrated with othr incoming signals from lower, higher and same-level processing stages. Lower = earlier in processing stream

• Sub-cortical nuclei = Tight cluster of neuron's cell bodies
• Gray matter = Cortex + sub-cortical nuclei
• White matter = Myelinated axons of neurons

Thalamus = Massive structure on top of midbrain, deep in centre of brain

• Main relay station for incoming sensory signals. Receives downward-going inpput from higher areas, modulating relay of sensory signals. Constantly changing perception of world

Cerebral cortex = Thin layers of neurons covering hemisphere

Corpus callosum = Thick bundle of axons connecting the 2 hemispheres - does all signal transfer

Hypothalamus = Small structure in front of and below the thalamus

• Directly connected to pituitary gland.  Gateway to endocrine system

Basal ganglia = Nuclei surrounding thalamus

• Involved in motor control processes. Consists of globus pallidus, putamen and caudate
• Putamen and caudate = Corpus striatum

Pathway of signals: a. Integrated with other signals    b. Ganglion cells send signals to thalamus   c. Each cell has electroconnections to make connections to each other   d. Combined input determines if cell becomes active   e. If overall input isn't strong enough, neuron won't respond

Cortical = Cingulate cortex directly above corpus callosum connected to hypothalamus and olfactory system.

Structures of brain:

• Brainstem --> Hindbrain & midbrain     Hindbrain --> Medullla, pons, cerebellum
• Medulla + pons --> Spinal cord enters brain    Cerebellum is NOT part of brain stem

Cerebellum function = Balance and motor learning

• Midbrain - above the pons = combines info from different sense modalities
• Mesencephalon = Midbrain    Diencephalon = Forebrain    Telencephalon = Forebrain

Central hemispheres: From diencephalon --> cerebrum. Divided into 2 hemispheres. Hemispheres covered in cerebral cortex and contains several groups of sub-cortical nuclei

Cerebral cortex = Layer of neurons covering each hemisphere

Sub-cortical = Near complete circle formed by fornix and hippocampus, ending in mammillary body and amygdalae.

Limbic system = Interconnected cortical & sub-cortical areas with role in memory and emotion

• Amygdala is part of it. Occipital lobe (back) - visual
• Temporal lobes (sides) - auditory     Parietal lobe (top) - somatosensory, inter-sensory, sensory-motor integration        Frontal lobe (front) - planning and motor output

Sensory signals from diencephalon are relayed to appropriate primary sensory cortex                 Visual signals to cortex (occipital), auditory signals to cortex (temporal), signals from skin, muscles and joints to somatosensory cortex (parietal lobe).

Retinotopic map = Visual signals from neighbouring retinal positions arrive at neighbouring positions in the primary visual cortex.

Tonotopic map = Auditory signals from adjacent areas of cochlea arive at adjacent areas in primary auditory cortex.

Topographic representation = Inside specific sensory areas, signals arrive at positions corresponding to position of receptor cells.

Somatotopic map = Signals from hand arrive in hand areas of somatosensory cortex which is next to arm area, next to shoulder e.t.c. (somatosensory nomunculus).

• Signals are identical -> How the incoming signal is interpreted depends on location it arrives
• Signals are transmitted in only 1 direction.
• Input from lower processing stages (bottom up/feed-forward), from higher processing stages (top down/feedback), from neighbouring regions in the same area (lateral) 

Cortical motor areas --> Located in frontal cortex at boundary to parietal cortex

Motor and promotor cortex --> Involved in planning, monitoring and sensory guidance of movements

Primary motor cortex --> Motor neurons send axons directly down spinal cord

Cortical motor areas --> Interconnected with 2 sub-cortical structures forming complex motor control circuits