Behavioral neuroscience
-
Behavioral neuroscience · Jun 1998
Induction of long-term receptive field plasticity in the auditory cortex of the waking guinea pig by stimulation of the nucleus basalis.
Learning induces neuronal receptive field (RF) plasticity in primary auditory cortex. This plasticity constitutes physiological memory as it is associative, highly specific, discriminative, develops rapidly, and is retained indefinitely. This study examined whether pairing a tone with activation of the nucleus basalis could induce RF plasticity in the waking guinea pig and, if so, whether it could be retained for 24 hr. ⋯ The physiological effectiveness of NB stimulation was assessed later while subjects were anesthetized with urethane by noting whether stimulation produced cortical desynchronization. Subjects in which NB stimulation was effective did develop RF plasticity and this was retained for 24 hr. Thus, activation of the NB during normal learning may be sufficient to induce enduring physiological memory in auditory cortex.
-
Behavioral neuroscience · Aug 1997
Normal conditioned inhibition and extinction of freezing and fear-potentiated startle following electrolytic lesions of medical prefrontal cortex in rats.
The authors investigated the role of medial prefrontal cortex (mPFC) in the inhibition of conditioned fear in rats using both Pavlovian extinction and conditioned inhibition paradigms. In Experiment 1, lesions of ventral mPFC did not interfere with conditioned inhibition of the fear-potentiated startle response. ⋯ In both Experiments 2 and 3, extinction of fear to contextual cues was also unaffected by the lesions. These results indicate that ventral mPFC is not essential for the inhibition of fear under a variety of circumstances.
-
Behavioral neuroscience · Oct 1996
Induction of receptive field plasticity in the auditory cortex of the guinea pig during instrumental avoidance conditioning.
Classical tone conditioning shifts frequency tuning in the auditory cortex to favor processing of the conditioned stimulus (CS) frequency versus other frequencies. This receptive field (RF) plasticity is associative, highly specific, rapidly acquired, and indefinitely retained-all important characteristics of memory. The investigators determined whether RF plasticity also develops during instrumental learning. ⋯ Long-term RF plasticity developed in all subjects (N = 6). Two-tone discrimination training also produced RF plasticity, like classical conditioning. Because avoidance responses prevent full elicitation of fear by the CS, long-term RF plasticity does not require the continual evocation of fear, suggesting that neural substrates of fear expression are not essential to RF plasticity.
-
Behavioral neuroscience · Aug 1996
Increases in vocalization and motor reflex thresholds generated by the intrathecal administration of serotonin or norepinephrine.
The capacity of serotonin and norepinephrine to elevate the thresholds of spinal motor reflexes (SMRs), vocalizations during shock (VDSs), and vocalization afterdischarges (VADs) when administered into the spinal subarachnoid space was evaluated. Both monoamines generated dose-dependent increases in the thresholds of all 3 responses. ⋯ Threshold increases generated by serotonin were also partially reduced by phentolamine. These results indicate that dorsal horn neurons that underlie flexion reflex generation (SMR) and the rostral transmission of pain information (VDS and VAD) have similar thresholds of inhibition to spinopetal monoaminergic projections.
-
Behavioral neuroscience · Dec 1985
Case ReportsDiminished ability to interpret and report internal states after bilateral medial temporal resection: case H.M.
These experiments centered around H. M., a 54-year-old man who became amnesic 27 years ago after a bilateral resection in the medial temporal lobe region for epilepsy. In order to document the clinical reports that he rarely comments on such internal states as pain, hunger, and thirst, his thermal pain perception was examined in relation to his other somatosensory capacities, and his reports of hunger and thirst were assessed before and after meals. ⋯ M.'s information about internal states is less available or less accessible than normal and that his impairment is not attributable to his well-documented memory deficit. Instead, it is believed that the bilateral resection of the amygdala accounts for H. M.'s poor appreciation of his internal states.