Part-1 Notes -Complex Behaviour: For Part-2 of these notes Check this Video link-ruclips.net/video/fa7Y-97YnLw/видео.html Complex behavior- The simplest unit of behaviour is the reflex. Behavioural patterns were initially thought to have been brought about by long and complex chain of reflexes. But behaviour is not all about external stimuli; it is also based on internal physiological conditions and spontaneous reactions controlled by nervous, hormonal and muscular systems. However, one can learn some of the basic features of behavioural mechanisms through the study of properties which reflexes share with more complex patterns and which can be clearly related to the properties of individual nerve cells. On the operation of the nerve cells, all behaviour depends. It is difficult to draw a firm line between reflexes and complex behaviour. Complex behaviour can incorporate many reflexes. For example, the swallowing reflex is the culmination of elaborate food-seeking behaviour. Complex behaviour, thus, is the product of an integrated series of changes in cell chemistry; initiated by receptor cells and carried on by sensory interneurons and motor cells and muscles. For example, singing in a cricket or a bird, where the body works due to the coordination of nerves, muscles and sense organs. The nervous system is remarkable in the sense that it not only responds to stimuli but also possesses a remarkable ability to preserve the effect of previous stimuli for a shorter or longer period. Charles Sherrington (1906), the father of modern neurophysiology, considered ways in which reflexes operate and how the central nervous system integrates them into adaptive behaviour by combining information gathered from different sources, arranging them into sequences of action and allocating priorities. The properties of reflexes and complex behaviour are: (a) Latency: Latency is the delay between giving a stimulus and seeing its effect. Latency in response is exhibited by both reflexes and complex behaviour. When a dog encountering a painful stimulus, the latency between the encountering of the stimulus and showing of flexion reflex (that is, withdrawal of the leg), lies between 60 and 200 milliseconds. Of this delay, a small fraction of time is taken for nerve impulses to be conducted along axons while the majority of the delay is due to the synapses (the term coined by Sherrington) between one neuron and the next. Thus, the delays between stimulus and response in complex behaviour are due to the fact that, in the chain between receptors and effectors, there are often dozens of synapses to cross. Another example of latency can be cited from the toad’s tongue flip to the escape of a cockroach. Slowed-down film shows that just before the toad’s tongue flips out of its mouth and strikes, the cockroach can sense it and would run out of reach. The important cue is the tiny gusts of wind produced by the toad’s movement which are picked up by the cockroach through many tiny wind-sensitive hairs on its cerci. The critical gust of wind occurred, on average, 41 ms (milliseconds) before the tongue starts emerging from the mouth. The latency period between the puffs of air and the cockroaches reaction (escape behaviour) is 44ms, which is sufficient for it to escape. It is often difficult to measure latencies for complex behaviour. It has been observed with reflexes that the stronger the stimulus, the shorter the latency. Some evidences suggest that the same is true for certain complex behaviour. Hinde (1960), working on chaffinches (Fringilla coelebs), was able to measure the latency between presenting various frightening stimuli and how soon they gave their first alarm calls. He observed that the stimulus which the strongest produced the shortest latency. (b) Summation: It has been observed that sometimes individual neurons respond only after they have received several post-synaptic potentials and, thus, are able to summate (add up) excitation coming either at different times (temporal summation) or from different places (spatial summation). An example of summation at the level of reflex is provided by Sherrington (1906), through the scratch reflex of the dog. When an irritating stimulus is elicited in the dog’s back, the hind leg on the same side is brought forward and is rhythmically scratched at the spot. First, weak stimuli are given singly at two points of the skin (A and B), 8 cm apart. They do not evoke the reflex. When both the points are stimulated simultaneously the reflex appears with a latency of about 1 second. Thus, neither is strong enough alone to evoke scratching, but are effective when given together. Fig. 5.8 shows the above spatial summation. Spatial Summnation Summation in more complex behaviour occurs between stimuli of quite different types, which are perceived by different sense organs. The sight and smell of food plus the sound of utensils summate when we are hungry. Male rats respond sexually to a combination of visual, olfactory and tactile stimuli from a receptive female. Generally, young male rats do not respond unless any two such sources are available. However, mature males, with previous experience, will respond to one type of stimulus alone (a case of temporal summation). (c) ‘Warm-up’ or Facilitation or ‘Motor- recruitment’: At first some reflexes do not appear at full strength. But, when with no change to the stimulus, their intensity increases over a few seconds. Such type of reflexes are said to be ‘Warm-up’, where neurons show synaptic facilitation, each successive postsynaptic potential (PSP) being larger than the previous one. Hinde (1954) found that when an owl is shown to chaffinches it shows a type of ‘warm-up’ effect. The bird gives out a mobbing call in response to the owl. The number of calls given by the chaffinch after the owl is shown is counted in successive 10-second periods. It was observed that the bird begins by calling at a relatively low rate and the maximum calling rate is reached at about 2-5 minutes, after which it gradually declines (Fig. 5.9). Chaffinch Similar type of ‘warm-up’ effect is also exhibited by a pet dog when it encounters an auditory or olfactory stimuli of any unwanted trespasser. Initially the dog responds with slow barking, the intensity increases and then gradually declines. Sherrington showed that such ‘warm-up’ in some reflexes is due to summation of stimuli which evokes a response from more and more nerve fibres, producing stronger concentration. This phenomenon was named by Sherrington ‘motor recruitment’. Such type probably also occurs with complex behaviour, not only in the change of intensity but also in the nature of the behaviour. This was amply exemplified by Sherrington (1917) from what he named as the cat’s ‘pinna reflex’. At first repeated tactile stimulation to the cat’s ear causes it to be laid back. If the stimulation persists, the ear is fluttered, subsequently the cat shakes its head and, when all the above fails to remove the irritation, it brings its hind leg up and scratches. It is clear that here more is involved than the recruitment of a few extra motor neurons. Recruitments are also made to mechanisms which control patterns of movement such as ear-fluttering, head shaking, and scratching. All these mechanisms are probably activated in some way by stimuli to the ear, but their thresholds are different, with the laying back on the ear being the lowest threshold. Workers studying complex behaviour generally rank the patterns they observe on an intensity scale of increasing thresholds.
Part-1 Notes -Complex Behaviour:
For Part-2 of these notes Check this Video link-ruclips.net/video/fa7Y-97YnLw/видео.html
Complex behavior-
The simplest unit of behaviour is the reflex. Behavioural patterns were initially thought to have been brought about by long and complex chain of reflexes. But behaviour is not all about external stimuli; it is also based on internal physiological conditions and spontaneous reactions controlled by nervous, hormonal and muscular systems.
However, one can learn some of the basic features of behavioural mechanisms through the study of properties which reflexes share with more complex patterns and which can be clearly related to the properties of individual nerve cells. On the operation of the nerve cells, all behaviour depends.
It is difficult to draw a firm line between reflexes and complex behaviour. Complex behaviour can incorporate many reflexes. For example, the swallowing reflex is the culmination of elaborate food-seeking behaviour. Complex behaviour, thus, is the product of an integrated series of changes in cell chemistry; initiated by receptor cells and carried on by sensory interneurons and motor cells and muscles.
For example, singing in a cricket or a bird, where the body works due to the coordination of nerves, muscles and sense organs. The nervous system is remarkable in the sense that it not only responds to stimuli but also possesses a remarkable ability to preserve the effect of previous stimuli for a shorter or longer period.
Charles Sherrington (1906), the father of modern neurophysiology, considered ways in which reflexes operate and how the central nervous system integrates them into adaptive behaviour by combining information gathered from different sources, arranging them into sequences of action and allocating priorities.
The properties of reflexes and complex behaviour are:
(a) Latency:
Latency is the delay between giving a stimulus and seeing its effect. Latency in response is exhibited by both reflexes and complex behaviour. When a dog encountering a painful stimulus, the latency between the encountering of the stimulus and showing of flexion reflex (that is, withdrawal of the leg), lies between 60 and 200 milliseconds.
Of this delay, a small fraction of time is taken for nerve impulses to be conducted along axons while the majority of the delay is due to the synapses (the term coined by Sherrington) between one neuron and the next. Thus, the delays between stimulus and response in complex behaviour are due to the fact that, in the chain between receptors and effectors, there are often dozens of synapses to cross.
Another example of latency can be cited from the toad’s tongue flip to the escape of a cockroach. Slowed-down film shows that just before the toad’s tongue flips out of its mouth and strikes, the cockroach can sense it and would run out of reach. The important cue is the tiny gusts of wind produced by the toad’s movement which are picked up by the cockroach through many tiny wind-sensitive hairs on its cerci.
The critical gust of wind occurred, on average, 41 ms (milliseconds) before the tongue starts emerging from the mouth. The latency period between the puffs of air and the cockroaches reaction (escape behaviour) is 44ms, which is sufficient for it to escape.
It is often difficult to measure latencies for complex behaviour. It has been observed with reflexes that the stronger the stimulus, the shorter the latency. Some evidences suggest that the same is true for certain complex behaviour.
Hinde (1960), working on chaffinches (Fringilla coelebs), was able to measure the latency between presenting various frightening stimuli and how soon they gave their first alarm calls. He observed that the stimulus which the strongest produced the shortest latency.
(b) Summation:
It has been observed that sometimes individual neurons respond only after they have received several post-synaptic potentials and, thus, are able to summate (add up) excitation coming either at different times (temporal summation) or from different places (spatial summation). An example of summation at the level of reflex is provided by Sherrington (1906), through the scratch reflex of the dog.
When an irritating stimulus is elicited in the dog’s back, the hind leg on the same side is brought forward and is rhythmically scratched at the spot. First, weak stimuli are given singly at two points of the skin (A and B), 8 cm apart. They do not evoke the reflex.
When both the points are stimulated simultaneously the reflex appears with a latency of about 1 second. Thus, neither is strong enough alone to evoke scratching, but are effective when given together. Fig. 5.8 shows the above spatial summation.
Spatial Summnation
Summation in more complex behaviour occurs between stimuli of quite different types, which are perceived by different sense organs. The sight and smell of food plus the sound of utensils summate when we are hungry.
Male rats respond sexually to a combination of visual, olfactory and tactile stimuli from a receptive female. Generally, young male rats do not respond unless any two such sources are available. However, mature males, with previous experience, will respond to one type of stimulus alone (a case of temporal summation).
(c) ‘Warm-up’ or Facilitation or ‘Motor- recruitment’:
At first some reflexes do not appear at full strength. But, when with no change to the stimulus, their intensity increases over a few seconds. Such type of reflexes are said to be ‘Warm-up’, where neurons show synaptic facilitation, each successive postsynaptic potential (PSP) being larger than the previous one.
Hinde (1954) found that when an owl is shown to chaffinches it shows a type of ‘warm-up’ effect. The bird gives out a mobbing call in response to the owl. The number of calls given by the chaffinch after the owl is shown is counted in successive 10-second periods. It was observed that the bird begins by calling at a relatively low rate and the maximum calling rate is reached at about 2-5 minutes, after which it gradually declines (Fig. 5.9).
Chaffinch
Similar type of ‘warm-up’ effect is also exhibited by a pet dog when it encounters an auditory or olfactory stimuli of any unwanted trespasser. Initially the dog responds with slow barking, the intensity increases and then gradually declines.
Sherrington showed that such ‘warm-up’ in some reflexes is due to summation of stimuli which evokes a response from more and more nerve fibres, producing stronger concentration. This phenomenon was named by Sherrington ‘motor recruitment’.
Such type probably also occurs with complex behaviour, not only in the change of intensity but also in the nature of the behaviour. This was amply exemplified by Sherrington (1917) from what he named as the cat’s ‘pinna reflex’.
At first repeated tactile stimulation to the cat’s ear causes it to be laid back. If the stimulation persists, the ear is fluttered, subsequently the cat shakes its head and, when all the above fails to remove the irritation, it brings its hind leg up and scratches. It is clear that here more is involved than the recruitment of a few extra motor neurons.
Recruitments are also made to mechanisms which control patterns of movement such as ear-fluttering, head shaking, and scratching. All these mechanisms are probably activated in some way by stimuli to the ear, but their thresholds are different, with the laying back on the ear being the lowest threshold. Workers studying complex behaviour generally rank the patterns they observe on an intensity scale of increasing thresholds.
thanks mam
Mashallah amazing ma'am 💝
Thank you 👍🏻
Pattern or type mein kya difference hain behaviour mein
Thanku so much mam❤️😘😘😘😘
Welcome
Nice video ma'am
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Glad you liked it..
Thanks mam for making video on this topic and I am desperately waiting for your next video on this topic.
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Sure Stay tuned...
Here is Part-2 Reflex and Complex behavior on your Request
ruclips.net/video/fa7Y-97YnLw/видео.html
@@mindsminetutorialsmaryamkhilji mam please make a video on Motivation
@@116.priyanshukumar3 soon will be uploaded
@@mindsminetutorialsmaryamkhilji thanks Mam.