Neural circuits in the primary auditory cortex (A1) can reorganize themselves depending on the type of auditory sensory cues which can then last throughout the life of the organism. It is hypothesized that the activation of the noradrengic neurons in response to stimuli leads to the strengthening of specific synapses in the cortex which results in the appropriate response. However, the changes that these neurons themselves undergo due to experience or the changes in the neural circuitry between these neurons and neurons of the cortex are unclear. The present study was aimed at understanding how the activity of locus coeruleus neurons leads to cortical plasticity through norepinephrine. The first step was to determine the effect of sensory …show more content…
Blocking the receptors in the A1 neurons with the antagonist phenotolamine before pairing impeded the effects of pairing, but once the antagonist was removed, the tuning curve shifted towards the paired frequency. This indicated that norepinephrine is required for inducing cortical plasticity. Antagonizing receptors 30 minutes after pairing caused the tuning curve to revert back to the best frequency before pairing. This suggested that norepinephrine is essential for long-term plasticity in A1. Blocking the NMDA receptors in locus coeruleus neurons with AP5 during pairing reduced the duration for which modification lasted in the A1 neurons suggesting that locus coeruleus plasticity is also required for maintaining long term plasticity in A1 …show more content…
Initially, the animals responded best to 4 kHz tones at ≥50 dB SPL but the response was low to 20-40 dB SPL tones. Pairing was then done between 4 kHz tones at 30 dB SPL and locus coeruleus stimulation. Recordings that were taken 12 hours after pairing showed that the ability of the rats to detect 20-40 dB SPL tones improved significantly and lasted for up to 20+ days in some cases. This plasticity was not detected when the locus coeruleus neurons were blocked with AP5. The final experiment was to determine the role of locus coeruleus pairing on reversal learning. Animals were trained to respond initially to 4 kHz tone which was then shifted to 16 kHz. It was found that unpaired rats took 20+ days to adjust to this change while it required only half the time for animals in which locus coeruleus pairing was done on the day of the change. These results suggested that the ability of the animals to perceive auditory stimuli and maintain these long-term changes was dependent on locus coeruleus plasticity. This plasticity was also responsible for accelerating the reversal learning
In this experiment, we explore the effects of extinction on the subject. In previous exercises, the subject received a food pellet whenever it pressed the bar. However, in this experiment, the operant chamber is modified so that no food pellet will be delivered regardless of any bar pressing that may occur. Additionally, the pellet dispenser will also be muted so there will be no magazine sound that accompanies bar pressing. Therefore, both the primary reinforcer (food) and secondary reinforcer (magazine sound) are removed. For these experiments, the independent variable is the schedule of reinforcement and the dependent variable is the extinction rate. The schedule of reinforcement refers to the schedule that the reinforcer is provided, which in this case is never and the extinction rate refers to the time it takes for an operant response to be extinguished after the reinforcer is no longer provided. We considered extinction to be reached when the subject presses the bar no more than twice in a 5-minute period, as shown in the cumulative
Reinforcement contingencies change the way in which the animal responds,” (Slater 10-11).
When something changes in the inner environment it sends information to the receptor. The receptor sends information to the control center and then the control center sends instructions to the effector once the information is received from the control center it proceeds to either oppose or increase the stimulus. This process is designed to repeatedly work at restoring or maintaining homeostasis.
Skinner argues that ‘learning is accelerated by reinforcement: a stimulus that increases the probability of a response’ called ‘operant conditioning’ and it is not reliant on what triggered the response but...
Sound is localised to the ear by the pinna, travelling down the auditory canal, vibrating the eardrum. The eardrums vibrations are then passed down through the ossicles, three small bones known as the hammer, anvil and stirrup that then transfer the vibrations to the oval window of the cochlea. The cochlea is filled with fluid that when exposed to these vibrations stimulate the sterocilia. This small hair cells "wiggle" along to certain frequencies transferring the vibrations into electrical impulses that are then sent to the brain. If the ear is exposed to noise levels of too high an intensity the sterocilia are overstimulated and many become permanently damaged . (Sliwinska-Kowalska et. All,
Another researcher has stated that instead of there being additional connections, the synaesthesia might be a result from disinhibited feedback in neural pat...
Kanske, P., Heissler, J., Schönfelder, S., Forneck, J., & Wessa, M. (2013). Neural correlates of
From this point, vibration of the connective membrane (oval window) transforms mechanical motion into a pressure wave in fluid. This pressure wave enters and hence passes vibrations into the fluid filled structure called the cochlea. The cochlea contains two membranes and between these two membranes, are specialized neurons or receptors called hair cells. Once vibrations enter the cochlea, they cause the lower membrane (basilar membrane) to move in respect to the upper membrane (i.e. the tectorial membrane in which the hair cells are embedded). This movement bends the hair cells to cause receptor potentials in these cells which in turn cause the release of transmitter onto the neurons of the auditory nerve.
Stage 3: After Conditioning. Now the conditioned stimulus (CS) has been associated with the unconditioned stimulus (US) to create a new conditioned response (CR).” (McLoed. 2008)
M.M. Merzenich, J. K. (1983). Topographical reorganization of somatosensory cortial areas 3b and 1 in adult monkeys following restrictive deafferentation. Neuroscience, 33-55.
Classical conditioning refers to a type of learning in which a previously neutral stimuli took on the ability to stimulate a conditioned response in an individual (Gormezano & Moore, 1966). To prove that environment was more impactful than genetics, Watson conducted an experiment on an infant, little Albert. Initially, Albert showed little fear towards rats. When Watson repeatedly exposed Albert to the rat accompanied by a loud noise, the latter began to develop fear towards not just the rat but also other furry animals. Watson successfully showed that the acquisition of a phobia can be explained by classical conditioning (Watson & Watson, 1921). Regardless of their genes, the associations of the right stimuli can result in the development of a new behaviour in any individual.
Hearing loss is a major global public health issue. Hearnet (2017) defines hearing loss as “a disability that occurs when one or more parts of the ear and/or the parts of the brain that make up the hearing pathway do not function normally” (para. 1). There are many different types of hearing loss, which can have multiple causes, giving each individual experiencing the issue a unique hearing loss case. These types include Auditory Processing Disorders, when the brain has problems processing sound information; Conductive Hearing Loss, a problem with the outer or middle ear which prevents sound making its way to the inner ear; and Sensorineural Hearing Loss, when the Cochlea or auditory nerve is damaged and cannot
Classical conditioning and operant conditioning both played a key role in the history of the study of learning, but, as argued by B.F Skinner, there are key differences to be noted between the two (Gleitman, Gross, Reisberg, 2011).
Classical conditioning is a technique of learning that occurs when an unconditional stimulus is paired with a conditional stimulus. The unconditional stimulus is biologically potent, the conditional stimulus is neutral (Kalat, 2011). Example of each is taste of food and sound of tuning fork respectively. After repeated pairing, the organism exhibits a conditional response to the conditional stimulus. The conditional response is similar to the unconditioned response though it is relatively impermanent and is acquired through experience (Kalat, 2011).
Learning is defined as a “process of change that occurs as a result of an individual’s experience” (Mazure, 2006). Researchers assume that the process of learning follows certain general principles, which were developed, into the general process learning theories. These include operant conditioning and classical conditioning which has been put forward by leading psychologists like Pavlov, B.F.Skinner and Thorndike. However, in learning, operant and classical conditoning are opposed by biological constraints that state that there are limitations to the theories. Some of these biological constraints on learning will be discussed below.