Neuronal responses in amygdala and nucleus accumbens during operant rewarding stimuli in the rat
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$10 NEURONAL RESPONSES IN A~GDALA AND NUCLEUS ACCUMBENS DURING OPERANT REWARDING STIMULI IN THE RAT KEN-ICHIRO ~RAMOTO*, TAKETOSHI ONO, RYOKO SHIBATA* and KIYOMI NAKAMURA*, Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama 930-01, Japan Single unit activity was recorded from the amygdala (AH) and the nucleus accumbens (NAC) of conscious rats during a tone discrimination operant task. Stimulating electrodes were implanted chronically in the posterior lateral hypothalamus (pLHA) and ventral tegmental area (VTA). The rat was fixed stereotaxically, but permitted to lick a spout automatically pushed close to the mouth. Licking caused either a drop of juice to be released from the tube or intracranial self-stimulation (ICSS) in the pLHA or VTA. The task included three discriminative cue tones:ll KHz for ICSS, 3 KHz for juice and 7KHz for no reward. One tone was presented at random for 2.0 sec prior to each task. In the corticomedial nuclear group of the AM, two thirds of the neurons responded to one or both rewarding stimuli, and half generally responded to tones that indicated rewards, but not to a tone associated with no reward. Responses to both rewards were usually in the same direction, and most were inhibitory. In the basolateral nuclear group of the AM, responses were slightly different from those in the corticomedial group. Although few neurons responded, inhibitory or excitatory responses to both tone and reward were observed. On the other hand, most of the responding NAC neurons increased firing in the reward period, and these responses continued for a rather long period of time. The data suggest that AM neurons might be important in reward related learning, while NAC neurons might be concerned with rewarding behavior. STIMULUS CONTEXT DEPENDENT RESPONSES OF MONKEY PREFRONTAL CORTEX NEURONS TAKETOSHI ONO, KAZU>~SA YA~TANI*, HITO0 NISHINO, ~SAJI FUKUDA*, HISAO NISHIJO *. Depart. of Physiol., and Neurosurg., Fac. of Med., Toyama Ned. and Pharmaceu. Univ., Sugitani, Toyama 930-01, Japan. To elucidate higher order integration for decision making based on learning and memory, single-unit activity was recorded from the prefrontal cortex (PFC) of the monkey during TV-controlled and bimanual: i) delayed matching-to-sample (DMS); 2) discrimination tasks with go and no-go responses (Go/No-Go) and during 3) bar-press feeding tasks depending on discrimination of food and non-food objects, i) Of 265 neurons recorded during DMS, 156 changed their firing rates in one or more periods. Most (92%, 143/156) responded in either one or both of the first and the second cue periods. Among these, 120(84%) responded nonspecifically to different shapes, sizes and colors of the cue, i.e. the response did no depend on the physical properties of the objects, or use of the ipsi- or contralateral hand. 2) Of 181 neurons recorded during Go/No-Go, 118 changed their firing rates in one or more periods. Of 82 neurons that responded in the cue period, 46(56%) responded differentially to go and no-go cues (differential neurons). 3) Of 156 neurons recorded during bar-press feeding tasks, 116 changed their firing rates in one or more phases. Of 93 neurons that responded in the discrimination phase, 58(62%) discriminated food and non-food objects (discriminative neurons). 4) Of 52 neurons that responded during DMS, 28(54%) were differential or discriminative during Go/No-Go or bar-press feeding tasks. Most (73%, 11/15) of the neurons that responded in the delay period of DMS were differential or discriminative during Go/No-Go or bar-press feeding tasks, as were 55%(24/44) and 58%(15/26) of the neurons that responded in the cue and reward periods, respectively. The results suggest that neurons that responded in the delay period during DMS may be important in decisions for movement initiation in learned task situations.
Transcript of Neuronal responses in amygdala and nucleus accumbens during operant rewarding stimuli in the rat
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NEURONAL RESPONSES IN A~GDALA AND NUCLEUS ACCUMBENS DURING OPERANT REWARDING STIMULI IN THE RAT
KEN-ICHIRO ~RAMOTO*, TAKETOSHI ONO, RYOKO SHIBATA* and KIYOMI NAKAMURA*, Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama 930-01, Japan
Single unit activity was recorded from the amygdala (AH) and the nucleus accumbens (NAC) of conscious rats during a tone discrimination operant task. Stimulating electrodes were implanted chronically in the posterior lateral hypothalamus (pLHA) and ventral tegmental area (VTA). The rat was fixed stereotaxically, but permitted to lick a spout automatically pushed close to the mouth. Licking caused either a drop of juice to be released from the tube or intracranial self-stimulation (ICSS) in the pLHA or VTA. The task included three discriminative cue tones:ll KHz for ICSS, 3 KHz for juice and 7KHz for no reward. One tone was presented at random for 2.0 sec prior to each task. In the corticomedial nuclear group of the AM, two thirds of the neurons responded to one or both rewarding stimuli, and half generally responded to tones that indicated rewards, but not to a tone associated with no reward. Responses to both rewards were usually in the same direction, and most were inhibitory. In the basolateral nuclear group of the AM, responses were slightly different from those in the corticomedial group. Although few neurons responded, inhibitory or excitatory responses to both tone and reward were observed. On the other hand, most of the responding NAC neurons increased firing in the reward period, and these responses continued for a rather long period of time. The data suggest that AM neurons might be important in reward related learning, while NAC neurons might be concerned with rewarding behavior.
STIMULUS CONTEXT DEPENDENT RESPONSES OF MONKEY PREFRONTAL CORTEX NEURONS
TAKETOSHI ONO, KAZU>~SA YA~TANI*, HITO0 NISHINO, ~SAJI FUKUDA*, HISAO NISHIJO *. Depart. of Physiol., and Neurosurg., Fac. of Med., Toyama Ned. and Pharmaceu. Univ., Sugitani, Toyama 930-01, Japan.
To elucidate higher order integration for decision making based on learning and memory, single-unit activity was recorded from the prefrontal cortex (PFC) of the monkey during TV-controlled and bimanual: i) delayed matching-to-sample (DMS); 2) discrimination tasks with go and no-go responses (Go/No-Go) and during 3) bar-press feeding tasks depending on discrimination of food and non-food objects, i) Of 265 neurons recorded during DMS, 156 changed their firing rates in one or more periods. Most (92%, 143/156) responded in either one or both of the first and the second cue periods. Among these, 120(84%) responded nonspecifically to different shapes, sizes and colors of the cue, i.e. the response did no depend on the physical properties of the objects, or use of the ipsi- or contralateral hand. 2) Of 181 neurons recorded during Go/No-Go, 118 changed their firing rates in one or more periods. Of 82 neurons that responded in the cue period, 46(56%) responded differentially to go and no-go cues (differential neurons). 3) Of 156 neurons recorded during bar-press feeding tasks, 116 changed their firing rates in one or more phases. Of 93 neurons that responded in the discrimination phase, 58(62%) discriminated food and non-food objects (discriminative neurons). 4) Of 52 neurons that responded during DMS, 28(54%) were differential or discriminative during Go/No-Go or bar-press feeding tasks. Most (73%, 11/15) of the neurons that responded in the delay period of DMS were differential or discriminative during Go/No-Go or bar-press feeding tasks, as were 55%(24/44) and 58%(15/26) of the neurons that responded in the cue and reward periods, respectively. The results suggest that neurons that responded in the delay period during DMS may be important in decisions for movement initiation in learned task situations.
