The Nervous System & The Brain Can we get scared without thinking? Can we get excited and calm at the same time? Can your body react (while you don’t notice)? Does your brain make strong prescription drugs?

The nervous system

The nervous system The autonomic nervous system is the part of your nervous system that works “automatically.” It works continuously adjusting your body chemistry and alertness level without you having to think about. Opponent process: The autonomic nervous system is either “On” or “Off.” It cannot be both on and off at the same time. When a person gets excited, we cannot be relaxed at the same time. When we are calm, we can get excited, but if that happens we have to leave relaxation (temporarily) for a while. Colour vision works like this: if you stare at something too long, that receptor turns “off” and the opposite colour in that cone is activated (see After Image).

The Peripheral Nervous System The Sympathetic nervous system activates your body (through the Pons, Amygdala, and Reticular Formation). This changes…. Increased Heart rate Pupil dilation Increased Respiration Increased Muscle tone Your skin contracts and you start to sweat. All of this can be triggered without the interaction of the brain. Signals go right to the amygdala.

Peripheral nervous system II The Parasympathetic nervous system is responsible for calming you down. A chemical called Diazepam is secreted by the brain and slows down the body. This happens to be a very powerful sedative drug, but we don’t know where the brain makes it (only that we know it does make it) Again, this can happen without conscious interaction with the brain.

Parts is Parts Hypothalamus: Can act as a secreting organ, but primarily monitors the blood, constantly monitoring chemical levels in the blood Hippocampus: This organ help to process memories. It holds information in short term storage and helps to process that information into long term storage. Amygdala: The source of the emotions anger and fear. Thalamus: This part of the brain acts like a post office relaying information to the correct parts of the brain and then out to the body. Reticular formation: Part of the biological mechanism for arousal.

The Lobes The Frontal: This part of the brain develops last and is where judgment and decision making occur. Why is 16 the driving age? The Parietal: Sometimes called the somatosensory cortex, this is where your sense of touch and bodily movement is centered. The Occipital: Though there are several places in the brain that process visual information, most of them are here in the back of the head. The Temporal: This is where hearing is (both sides) and language interpretation is (left side only).

Neurons

The Synapse

Fear swings both ways If we talk about something like Fear, it can be created in the environment or it can come from an idea within you mind. If you come around a corner and bump into someone, you don’t have time to “think” about fear, it just happens. The signal goes straight to the amygdala and skips the frontal lobe. It takes your consciousness to calm you down again. If you are watching a scary movie and then you hear something outside a window, you may create fear where there was none before because you are thinking of all the negative possibilities.

Talking and Listening When we hear things, aural stimuli comes in through the ears and is interpreted by Wernick’s area in the left temple. Without this area, we could hear language, we just wouldn’t know what was being said. When we speak, a portion of the frontal lobe (Broca’s area) is helping us to turn brain signals into understandable verbal language. If something happens to this area we may be able to speak, but nothing understandable comes out, or we just can’t speak at all (Aphasia).

Dual function Parietal Lobe This lobe does two things: it houses the area of the brain that moves our muscles and it contains the area of the brain that houses a map of the surface of the body. This internal maps helps us to know what our body is doing when we can’t see and tells us if we are in pain. The motor cortex cannot directly receive signals, it has to rely on the sensory cortex. The sensory cortex cannot send signals to the body but can only receive them. So, these two parts of the brain must work closely together to coordinate movement of the body to react to stimuli coming from the skin.

Conclusions There’s a lot we still don’t know about the brain. What we think we know now may be disproven in 20 years and technology just makes it so that we can ask more questions, not that we get more answers. Human behaviour is so complicated that brain biology alone is never going to be the answer. Further the interaction between behaviour and brain biology is not consistent enough that we can accurately predict behaviour with any certainty.