- Created by: becky_99
- Created on: 20-12-19 19:04
Regulates the frequency and intensity of motor activity.
Guides attention and learning.
The brain's sensory relay for all senses except smell.
A region of subcortex involved in regulating the organism to its present and past environment; limbic structures include the amygdala, hippocampus, cingulate cortex, and mamillar bodies.
Responsible for the integration of motor commands to promote the smooth execution of improvement.
Subcortical areas of the brain
Suggested functions of each of these brain areas:
- Thalamus - sensory relay
- Basal ganglia - motor processes, attention (Parkinson's disease)
- Limbic system - emotion and memory
- Cerebellum - fine-tune motor output
Intelligence and the brain
Cortex - 4 lobes:
- Frontal - motor, planning, inhibition, social processing
- Parietal - sense of touch, spatial attention
- Occipital - vision
- Temporal - memory, emotion
- Thalamus - sensory relay
- Basal ganglia - motor processes, attention
- Limbic system - emotion, memory
- Cerebellum - fine-tune motor processes
What determines neuron function?
- E.g. dendrite density
- Axon length
- Axon width: speed
- Myelin sheath present: speed
- Sensory: dendrite in periphery; axon toward brain
- Motor: dendrite from brain; axon toward periphery
- Interneurons: neuron-to-neuron connections
Roth & Dicke (2005)
Defined intelligence as cognitive and behavioural flexibility.
Bodyweight vs. absolute brain weight.
The bigger the body, the bigger the brain:
- Neuron density was much higher in humans than other mammals
- They discussed the potential for human brains to have a higher number of synapses than other mammal brains
- The authors suggested that the number of cortical neurons could be an indicator of intelligence
Two things that do seem to correlate with behavioural and cognitive flexibility:
- Number of cortical neurons
- Speed of axon conduction of cortical neurons
It suggests that processing capacity is important.
Roth & Dicke (2005)
Problems with this review:
- The review mainly used data that compared human brains with the brains of other mammals
- What about differences in intelligence when comparing humans vs. other humans?
Recent evidence suggests that higher number of neurons correlates with a lower IQ (Genc et al., 2018).
Genc et al. (2018) found that those with higher IQs had less neurons per squared measurement.
- The authors argued that the neurons ability to prune unused dendritic branches in order to maintain the neural efficiency hypothesis of intelligence; intelligence is not as a result of how hard the brain works but rather how efficiently it works
Sensation is receiving the information from sensory sources.
Perception is elaborating on and interpreting the sensory stimulus.
The 5 physical senses
The sense and the type of energy detected from it:
- Vision - light
- Touch (tactile, somatosensory) - pressure, texture (mechanical) and heat
- Hearing (audition) - sound, vibration (mechanical)
- Taste - chemical
- Smell (olfaction) - chemical
Proprioception; kinaesthetic sense
Sense of body position and movement of the body:
- Afferent impulses from stretch receptor to the spinal cord
- Efferent impulses to alpha motor neurons cause contraction of the stretched muscle that resists/reverses the stretch
- Efferent impulses to antagonist muscles are damped (reciprocal inhibition)
What is the purpose of having sensory systems?
- Detect external and internal environments
- Trigger actions; protect self
- Receive feedback about own actions
Sensory systems are closely linked with motor systems.
The full system that detects stimuli (sensory system) and responds (motor system) can be called:
- Perceptual-motor system
- Sensorimotor system
The stretch reflex
- Muscle spindle senses stretch
- Sensory neuron conducts action potential
- Sensory neurons synapse with alpha motor neuron and interneuron
- Alpha motor neuron to quadriceps is stimulated while the alpha motor neuron to the hamstring is inhibited
- The quadriceps contract and the hamstrings relax
What areas of the human brain specialise in sensor
- Thalamus - processes and relays sensory information to the cortex
- Cerebellum - processes sensory feedback to fine-tune motor processes
Vision - primary visual cortex - occipital lobe.
Touch - primary somatosensory cortex - parietal lobe.
Hearing - primary auditory cortex - temporal lobe.
Smell - frontal lobe.
Taste - gustatory cortex - temporal and frontal lobe.
What is "out there" is not necessarily what we perceive "in here".
- The visual system "processes" the signals from the external world
- Visual system makes "best" guess based on available information
- We need to understand how the "processing", and the "guesses" work, to understand performance
- Located at the back of the eye
- Contains the photoreceptors
- Photoreceptors are neurons that detect light. If sufficient light strikes them, an action potential occurs
- Small depression in the retina
- Detects light from the centre of the visual field
- Visual field = the area of space that can be seen by the eye
All neurons: photoreceptors, bipolar cells, and ganglion cells are neurons.
Two types of photoreceptors
- Detect dim light and are specialised for night vision
- Not present in fovea
- Achromatic (colour blind)
- Have low acuity
- Are specialised for day vision
- Are concentrated in fovea
- Mediate colour vision
- Provide greater temporal and spatial resolution than rods
Light activates visual pigments in the outer segments of rods and cones, which causes the receptor to fire.
Ganglion cells are cells in the retina, after rods and cones, in the chain of neurons.
- Parvocellular neuron
- Magnocellular neuron
Small receptive field.
Slow conduction rate.
Concentrated in fovea.
- Detailed form analysis
- Spatial analysis
- Colour vision
Large receptive field.
Fast conduction rate.
Concentrated in periphery.
- Motion detection
- Temporal analysis
- Depth perception
How does information get from the eye to the brain
- Light bounces off an object and hits photoreceptors in the eye which are specialised neurons
- Photoreceptor fires, sending a signal to the next layers of neurons in the eye, bipolar neurons and ganglion neurons
- Axons of ganglion neurons exit the eye via the optic nerve and go to the thalamus area of the brain
- Neurons in the thalamus send the signal to the primary visual cortex of the brain, where the initial processing of the visual information takes place